← Product Code SGK · P220031

# LimiFlex Dynamic Sagittal Tether (P220031)

_Empirical Spine, Inc. · SGK · Feb 12, 2026 · Orthopedic · APPR_

**Canonical URL:** https://fda.innolitics.com/device/P220031

## Device Facts

- **Applicant:** Empirical Spine, Inc.
- **Product Code:** SGK
- **Decision Date:** Feb 12, 2026
- **Decision:** APPR
- **Device Class:** Class 3
- **Review Panel:** Orthopedic
- **Attributes:** Therapeutic

## Intended Use

The LimiFlex Dynamic Sagittal Tether is a motion-preserving spinal implant that is intended to provide dynamic flexion-restricting stabilization of the spine following a lumbar decompression. The LimiFlex Dynamic Sagittal Tether is indicated for use at one level from L3 to L5, in skeletally mature patients following surgical decompression for treatment of lumbar degenerative spondylolisthesis (Grade I per Meyerding classification in a lateral radiograph) with spinal stenosis. Patients consist of those with neurogenic claudication or radiculopathic symptoms, including leg pain, muscle weakness, and/or sensation abnormality, with or without back pain, who have been unresponsive for a minimum of three months of non-operative treatment and have a confirmed diagnosis through patient history and diagnostic studies using X-ray, MRI and/or CT.

## Device Story

LimiFlex Dynamic Sagittal Tether provides dynamic flexion-restricting stabilization for lumbar spine post-decompression; utilizes titanium spring couplers attached to UHMWPE straps wrapped around adjacent spinous processes. Increases segmental flexion bending stiffness to reduce motion in high-flexibility zone; maintains lordotic posture to engage facet joints. Implanted by surgeons in clinical setting. Output is mechanical stabilization; healthcare providers assess patient via radiographic imaging and clinical symptom relief (VAS, ODI). Benefits include motion preservation compared to fusion, reduced pain, and improved functional outcomes. Device is MR Conditional.

## Clinical Evidence

Prospective, multi-center, non-randomized, non-blinded clinical study (IDE G090131) with 299 subjects (140 investigational, 159 control). Primary endpoint: Month 24 composite clinical success (CCS) (ODI improvement ≥15, no neurologic decline, no secondary surgical intervention, no device failure). Investigational group success rate 76.7% vs. 64.6% control (MI analysis). Non-inferiority demonstrated (lower bound 95% CI > -12.5%). Spinous process fractures occurred in 17.1% of investigational subjects.

## Technological Characteristics

Materials: Titanium spring couplers, UHMWPE straps. Principle: Dynamic flexion-restricting stabilization via spring-loaded interspinous tether. Dimensions: Single size. Connectivity: None. Sterilization: Ethylene oxide (EO). Software: None. MR Compatibility: MR Conditional (1.5T/3.0T).

## Regulatory Identification

This device is a non-fusion, tension band implant that is intended to provide dynamic flexion-restricting stabilization of the spine following a lumbar decompression.

## Submission Summary (Full Text)

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# SUMMARY OF SAFETY AND EFFECTIVENESS DATA (SSED)

## I. GENERAL INFORMATION

Device Generic Name: Prosthesis, Spinous Process Tension Band Implant

Device Trade Name: LimiFlex Dynamic Sagittal Tether

Device Procode: SGK

Applicant’s Name and Address: Empirical Spine
18655 Madrone Parkway, Suite 180
Morgan Hill, California 95037

Date of Panel Recommendation: None

Premarket Approval Application: P220031
(PMA Number)

Date of FDA Notice of Approval: February 12, 2026

Breakthrough Device: Granted breakthrough device status on March 26, 2021 because the device and proposed indications for use met the program criteria.

## II. INDICATIONS FOR USE

The LimiFlex Dynamic Sagittal Tether is a motion-preserving spinal implant that is intended to provide dynamic flexion-restricting stabilization of the spine following a lumbar decompression. The LimiFlex Dynamic Sagittal Tether is indicated for use at one level from L3 to L5, in skeletally mature patients following surgical decompression for treatment of lumbar degenerative spondylolisthesis (Grade I per Meyerding classification in a lateral radiograph) with spinal stenosis. Patients consist of those with neurogenic claudication or radiculopathic symptoms, including leg pain, muscle weakness, and/or sensation abnormality, with or without back pain, who have been unresponsive for a minimum of three months of non-operative treatment and have a confirmed diagnosis through patient history and diagnostic studies using X-ray, MRI and/or CT.

## III. CONTRAINDICATIONS

The Empirical Spine LimiFlex Dynamic Sagittal Tether should not be implanted in patients with the following conditions:

- Posterior element anatomy inappropriate for interspinous fixation, including:

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○ Absence or fracture of spinous processes or posterior elements, or deformity that precludes secure device fixation,
○ Facet joint incompetence,
○ Prediction of resection of greater than 50% of spinous processes or facet joints during decompression of the instrumented segment,
○ Spondylolysis or isthmic spondylolisthesis at the instrumented level,
○ The estimated distance between the LimiFlex Dynamic Sagittal Tether strap attachment points (midpoint of the cranial edge of the cranial spinous process and the midpoint of the caudal edge of the caudal spinous process) is less than 30 mm on pre-operative lateral standing radiographs at the segment to be instrumented,
○ Posterior element tumor,
○ Severe osteoporosis.

- A primary diagnosis of facet-mediated back pain, defined as isolated axial back pain without associated buttock or leg pain, worsened by extension, in the presence of severe facet arthropathy on imaging and absence of radiographic neural compression.
- Symptomatic lumbar stenosis at the instrumented level that is not amenable to a direct surgical decompression
- Documented allergy to implant materials, including titanium or polyethylene
- Active systemic or local infection

## IV. Warnings and Precautions

The warnings and precautions can be found in the LimiFlex Dynamic Sagittal Tether labeling.

## V. Device Description

The LimiFlex Dynamic Sagittal Tether is an implant designed to provide dynamic flexion-restricting stabilization of the spine by increasing segmental flexion bending stiffness across the arc of motion through the use of dynamic titanium spring couplers attached to woven straps that wrap around adjacent spinous processes (through the interspinous ligament). The increased flexion bending stiffness is designed to reduce segmental motion within the high flexibility zone where most activities of daily living occur, as well as to maintain the spine in a lordotic posture of relative extension where the facet joints are more engaged and able to resist anterior translation. A complete LimiFlex Dynamic Sagittal Tether consists of two (2) dynamic titanium spring couplers with integrated interconnections (fixed and adjustable) and attached ultra high molecular weight polyethylene (UHMWPE) straps. The LimiFlex Dynamic Sagittal Tether is illustrated in Figure 1 and Figure 2. A single size offering and associated part number is identified in Table 1.

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![img-0.jpeg](img-0.jpeg)
Figure 1: LimiFlex Dynamic Sagittal Tether

![img-1.jpeg](img-1.jpeg)
Figure 2: LimiFlex Dynamic Sagittal Tether Components

Table 1: LimiFlex Dynamic Sagittal Tether Catalog Numbers

|  Catalog Number | Description  |
| --- | --- |
|  KLF-3001 | LimiFlex Dynamic Sagittal Tether (includes complete packaged subject device and two (2) Leader single-use instruments)  |

# VI. ALTERNATIVE PRACTICES AND PROCEDURES

There are several other alternatives for the correction of lumbar degenerative spondylolisthesis (Grade I per Meyerding classification in a lateral radiograph) with spinal stenosis. Non-surgical alternatives include non-steroidal anti-inflammatory medications, analgesics, oral and epidural steroids, an initial period of rest, physical therapy and bracing. When non-surgical treatments cease to be effective, there are several

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surgical alternatives, which include but are not limited to, direct or indirect decompression with or without a device (fusion or non-fusion). Each alternative has its own advantages and disadvantages. A patient should fully discuss the available alternatives with their physician to select the option that best meets their clinical condition, lifestyle and expectations.

## VII. MARKETING HISTORY

The LimiFlex Dynamic Sagittal Tether was marketed by Simpirica Spine in Europe from 2009 through 2014 and was withdrawn from the European market in late 2014 upon the closure of Simpirica Spine due to financial reasons. The LimiFlex Dynamic Sagittal Tether has not been withdrawn from any distribution/ marketing in any country for known safety or effectiveness reasons.

## VIII. POTENTIAL ADVERSE EFFECTS OF THE DEVICE ON HEALTH

Below is a list of the potential adverse effects (e.g., complications) associated with the use of the device.

**Risks Associated with Any Surgery:**

General surgical risks include, but are not limited to:

- Complications from anesthesia such as allergic reaction, anaphylaxis, or other reactions
- Post-surgical pain, bruising, hematoma, swelling, or tenderness at the surgical site
- Complications from medication (e.g., nausea, vomiting, delirium or headache after the surgery)
- Blood loss requiring a blood transfusion
- Blood clots, including pulmonary emboli
- Infection (including urinary tract infection)
- Phlebitis
- Pneumonia
- Poor tissue healing
- Paralysis
- Atelectasis
- Wound complications (such as separation and bruising) and soft tissue damage
- Ileus or intestinal obstruction
- Septicemia
- Myocardial infarction
- Cardiac arrhythmia
- Stroke
- Death

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Risks Associated with Spinal Decompression Surgery:
Risks associated with spinal decompression surgery include, but are not limited to:
- Dural tear
- Cerebrospinal fluid leak
- Bowel, bladder or sexual dysfunction
- Organ damage
- Disc herniation
- Increased spinal instability requiring additional surgery
- Persistent stenosis requiring additional decompression
- Leg weakness or numbness
- Muscle and tissue injury or damage
- Spinous process fracture
- Cauda Equina damage
- Nerve injury, paralysis or weakness
- Epidural hematoma or bleeding
- Loss of spinal range of motion
- Spontaneous fusion at non-index levels due to heterotopic ossification, development of bridging bone or osteophytes
- Development of new spinal conditions, including but not limited to spinal stenosis and spondylolisthesis

Risks Associated with Posterior Lumbar Spine Surgery:
Risks associated with posterior lumbar spine surgery (including the LimiFlex Dynamic Sagittal Tether) include, but are not limited to:
- Sensitivity, allergy or chronic inflammation (e.g., foreign body reaction, bursitis) related to the implant material (titanium, polyethylene)
- Infection related to the device
- Dislocation, malpositioning or lack of fixation of the device after surgery
- Malalignment of anatomic structures
- Mechanical failure of the device, including device breakage, separation or disassembly
- Incomplete healing after the procedure
- Unsatisfactory clinical results that may include increased pain at the device level and exacerbation of symptoms
- Fracture and/or erosion of the spinous processes
- Nerve and/or vascular damage
- Spontaneous fusion due to heterotopic ossification, development of bridging bone or osteophytes
- Additional surgery due to any of the above factors (additional surgery includes revision, removal, reoperation, or supplemental fixation at the treated level)
- Inability to complete the implantation of the device which may require the use of another treatment modality to complete the therapy
- Pain associated and/or attributed to the device

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For the specific adverse events (AEs) that occurred in the clinical study, please see Section X below.

## IX. SUMMARY OF NON-CLINICAL STUDIES

Non-clinical testing has been performed to characterize the properties and performance of the LimiFlex Dynamic Sagittal Tether and to demonstrate a reasonable assurance of safety and effectiveness to support PMA approval. These non-clinical evaluations included mechanical testing to evaluate safety and performance, as well as biocompatibility testing, sterilization, shelf life and packaging validation, and magnetic resonance (MR) compatibility testing.

## A. Laboratory Studies

The laboratory studies conducted are described in Table 2 below.

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Table 2: Implant Performance Testing

|  Test | Purpose | Test Method | Acceptance Criteria | Results  |
| --- | --- | --- | --- | --- |
|  Implant  |   |   |   |   |
|  Biocompatibility | Demonstrate that the LimiFlex Dynamic Sagittal Tether and Leader Accessory are biocompatible for their intended use | Cytotoxicity, sensitization, irritation, systemic toxicity, implantation, pyrogenicity, genotoxicity, chemical characterization and toxicological risk assessment (ISO 10993-1, 3, 5, 6, 10, 11, 17, 18) | ISO 10993 / Biocompatible for intended use | Results of testing in combination with toxicological risk evaluation demonstrated biocompatibility in line with the requirements of ISO 10993-1 for a permanent implant in contact with tissue/bone.  |
|  Sterilization Validation | Validate that the ethylene oxide (EO) sterilization process terminally sterilizes the packaged LimiFlex Dynamic Sagittal Tether and Leader Accessory per applicable standards. | Comparative resistance study; “over-kill” validation demonstrating the ½ cycle delivers sterility assurance level (SAL) of 10^{-6} with acceptably low endotoxin and EO residuals (AAMI TIR 16, EN 556, ISO 11135, 11138, 11737) | Demonstrated biological indicator kill in half-cycle; EO residual, endotoxin and bioburden testing per applicable AAMI and ISO standards for EO sterilization / All required biological indicators killed half-cycle; EO residuals and endotoxin below required thresholds | Full sterilization validation has been conducted per ISO 11135-1 and ISO 11135-2 to establish a Sterility Assurance Level (SAL) of at least 10^{-6}.  |

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|  Test | Purpose | Test Method | Acceptance Criteria | Results  |
| --- | --- | --- | --- | --- |
|  Biomechanical Validation | Demonstrate that the LimiFlex Dynamic Sagittal Tether provides a segmental resistance to flexion | Cadaveric testing of lumbar specimens in flexion/extension, lateral bending and axial rotation, with specimens in the intact, destabilized with LimiFlex Dynamic Sagittal Tether implanted conditions. | The LimiFlex Dynamic Sagittal Tether must provide dynamic flexion-restricting stabilization equivalent to the stability provided by spinal braces commonly used for lumbar fusion, as reported in published literature. | The study showed a 4.3° reduction of flexion-extension ROM (with a follower load) and a 0.57Nm/° increase in flexion stiffness in the lumbar spine after implantation of the LimiFlex Dynamic Sagittal Tether as compared to the intact condition following surgical destabilization.  |
|  Static Tensile Test | Demonstrate that the LimiFlex Dynamic Sagittal Tether meets performance criteria for static tensile strength and stiffness. | Static tensile testing adapted from ASTM F1717 | 100N min static yield strength; 11-13.5 N/mm stiffness | The acceptance criterion was met.  |
|  10-million Cycle Fatigue Test | Demonstrate that the LimiFlex Dynamic Sagittal Tether meets performance criteria for dynamic (10-million cycle) fatigue strength. Initial testing established “F-N” performance. | Dynamic tensile adapted from ASTM F1717 | Fatigue strength 100N at 10M cycles w/o failure and ≤1mm dynamic creep over 10M cycles | The acceptance criterion was met. The dynamic creep was ≤1.3% of the test specimen gauge length.  |

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|  Test | Purpose | Test Method | Acceptance Criteria | Results  |
| --- | --- | --- | --- | --- |
|  Leader Static Bending Test | Demonstrate that the Leader Accessory meets performance criteria for its intended use | Static loading of the Leader Accessory simulating worst-case loading during use | >114 N yield strength No component fracture | The acceptance criterion was met.  |
|  Wear Test | Demonstrate that the LimiFlex Dynamic Sagittal Tether does not generate biologically harmful wear debris during worst-case loading over maximum expected implantation duration | Multi-axial loading per ASTM F2624 with gravimetric assessment and fluid particulate analysis [1]. 10M cycle tensile loading at super-physiologic loads with gravimetric assessment of wear [3]. | No biologically harmful wear debris | The acceptance criterion was met.  |
|  Packaging and Shelf-Life Validations | Demonstrate that the LimiFlex Dynamic Sagittal Tether and packaging meet performance specifications after simulated transit and storage conditions as well as real-time aging. | Transit simulation followed by accelerated or real-time aging, followed by device and package performance testing | Device and packaging meet performance criteria after simulated transit and aging | Shelf life and transit validation studies, including assessments of packaging seal integrity, real time and accelerated aging testing, were conducted to demonstrate that the device packaging can maintain a sterile barrier over a 48-month shelf life.  |
|  MRI Compatibility Testing | Demonstrate that the LimiFlex Dynamic Sagittal Tether poses an acceptably low risk to safety or image quality in the MRI environment for | Translational attraction (ASTM F2052), Magnetically induced torque (ASTM F2213), RF-induced heating (ASTM F2182), MR | The LimiFlex Dynamic Sagittal Tether must be found to be at least MR Conditional | The nonclinical testing demonstrated that the Limiflex Sagittal Tether is MR Conditional.; see  |
|   | the LimiFlex Dynamic Sagittal Tether and packaging is not suitable for the MRI environment. |  |  | the LimiFlex Dynamic Sagittal Tether is not suitable for the MRI environment.  |
|  Safety and Safety Evaluation | Demonstrate that the LimiFlex Dynamic Sagittal Tether is able to perform safety and safety testing in the MRI environment for | Safety testing, safety testing, and safety testing | Safety testing, safety testing, and safety testing | Safety testing, safety testing, and safety testing  |

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|  Test | Purpose | Test Method | Acceptance Criteria | Results  |
| --- | --- | --- | --- | --- |
|   | 1.5-Tesla and 3-Telsa MRI conditions | image artifacts (ASTM F2119) |  | Section IX.A for MR scanning conditions.  |
|  User Validation | Validate that customer/user requirements for the LimiFlex Dynamic Sagittal Tether, Accessory and Instruments were successfully met | Simulated surgical implantation by qualified users with questionnaire to assess user requirements | All user requirements must be satisfactorily met per use surveys | The acceptance criterion was met.  |

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# B. Additional Studies

MR Compatibility testing was conducted to demonstrate that a person with an Empirical Spine LimiFlex Dynamic Sagittal Tether device may be safely scanned anywhere in the body at 1.5T or 3.0T under the following conditions. Failure to follow these conditions as summarized in Table 3 may result in injury:

Table 3: MRI Conditions for Person with Implanted LimiFlex Dynamic Sagittal Tether Device

|  Parameter | Condition  |
| --- | --- |
|  Device Name | Empirical Spine LimiFlex Dynamic Sagittal Tether  |
|  Static Magnetic Field Strength (B0) | 1.5T and 3.0T  |
|  Maximum Spatial Field Gradient | 20 T/m (2000 G/cm)  |
|  RF Excitation | Circularly Polarized (CP)  |
|  RF Transmit Coil Type | Integrated Whole Body Transmit Coil  |
|  Operating Mode | First Level Controlled Operating Mode  |
|  Scan Duration | 1 hour of continuous scanning in Normal Operating Mode without a cooling period  |
|  MR Image Artifact | The presence of LimiFlex Dynamic Sagittal Tether may produce an image artifact of 10mm. Some manipulation of scan parameters may be needed to compensate for the artifact.  |

# X. SUMMARY OF PRIMARY CLINICAL STUDY

The applicant performed a clinical study to establish a reasonable assurance of safety and effectiveness of the LimiFlex Dynamic Sagittal Tether when used to treat at one level from L3-L5 in skeletally mature patients following surgical decompression for treatment of lumbar degenerative spondylolisthesis (Grade I per Meyerding classification in a lateral radiograph) with spinal stenosis in the US under IDE G090131. Data from this clinical study were the basis for the PMA approval decision. A summary of the clinical study is presented below.

# A. Study Design

Subjects were treated between July 2017 to September 2020. The database for this PMA reflected data collected through September 28, 2022, and included a total of 299 subjects enrolled at 28 investigational sites.

The study was a prospective, multi-center, non-randomized, and non-blinded clinical study of the LimiFlex Dynamic Sagittal Tether. The prospective investigational and control arms were concurrently enrolled. The prospective control population was supplemented with retrospective control subjects (RCS). Balance between groups was achieved through subclassification using propensity scores. Subjects were considered enrolled in the study for the purposes of an intention-to-treat (ITT) analysis, only after they were treated (time of incision), with the exception of subjects for which no study

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device implantation was attempted due to violation of inclusion or exclusion criteria identified intra-operatively that could not reasonably be assessed prior to surgery. Subjects excluded prior to treatment, due to withdrawal of consent, arising medical difficulties (e.g., heart attack), documentation of ineligibility by circumstances unforeseen at the time of Informed Consent, etc. and subject excluded intra-operatively, are considered screening failures. Pre-operative data, including the reason for exclusion, was collected for screening failures. However, pre-operative data for screen failures may not be complete, as the subject may be determined to be a screen failure early in the screening process.

The control group was a combination of prospective and retrospective control subjects. The control group comprised subjects who were treated with a transforaminal lumbar interbody fusion (TLIF) with concomitant posterolateral fusion with pedicle screw instrumentation at a single level following decompression at one or two contiguous levels for treatment of lumbar degenerative spondylolisthesis (Grade I per Meyerding classification in a lateral radiograph) with spinal stenosis. Comparability of prospective and retrospective control subjects was ensured by requiring the same eligibility criteria for all subjects and confirmation of balance through subgroup analyses.

All radiographic endpoints were evaluated independently by a core laboratory (Medical Metrics, Inc.). Quantitative assessments (measurements) of intervertebral motion were produced by core lab trained analysts using specialized motion analysis software incorporating validated computerized techniques (i.e., 510(k) cleared QMA software) to ensure reproducibility.

Study oversight was provided by an independent Medical Monitor (MM), Data Safety and Monitoring Board (DSMB) and Clinical Events Committee (CEC). The MM oversaw the conduct of the clinical study including the safety of the subjects enrolled in the study. The DSMB met periodically upon completion of each interim safety analysis, or as needed, to review the cumulative results of the study, including incidence of spinous process fracture, and to evaluate any safety or efficacy issues that occurred during the course of the study. The CEC was responsible for the adjudication of any events that may be considered serious and/or device related, including but not limited to all spinous process fractures reported either by the investigational site or noted by the radiographic core laboratory, protocol deviations and any decrease in neurological status at 24 months post-treatment (Month 24) compared to baseline.

1. Clinical Inclusion and Exclusion Criteria

Enrollment in the LimiFlex Dynamic Sagittal Tether study was limited to subjects who met the following inclusion criteria in Table 4. Subjects were not permitted to enroll in the LimiFlex Dynamic Sagittal Tether study if they met any of the following exclusion criteria in Table 4.

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Table 4: Study Inclusion and Exclusion Criteria

|  Study Inclusion Criteria | Study Exclusion Criteria  |
| --- | --- |
|  • Lumbar degenerative spondylolisthesis (Grade I per Meyerding classification), at one level from L1 to S1, with radiographic confirmation using X-ray; ○ Grade I spondylolisthesis per Meyerding classification includes up to 25% anterior translation of a vertebra relative to the superior endplate of the subjacent vertebra at the index level. A patient is considered to have spondylolisthesis with a minimum 10% anterolisthesis at the affected level in a lateral x-ray image. • Lumbar spinal stenosis requiring decompression at up to two contiguous levels from L1 to S1, inclusive of the level diagnosed with degenerative spondylolisthesis, and confirmed radiographically using CT or MRI; ○ At the index level, lumbar spinal stenosis is at least moderate lumbar canal stenosis, defined as more than 25% reduction of the canal cross-sectional area compared with the next adjacent normal level, with nerve root crowding compared with the normal level, as determined by the investigator on CT scan or MRI. • Neurogenic claudication or radiculopathy symptoms including leg pain, muscle weakness, and/or sensation abnormality, with or without back pain as evidenced by patient history; • Persistent symptoms despite at least 3 months of conservative treatment that may include but is not limited to physical therapy, medications, and/or epidural injections; • A pre-operative Visual Analog Scale (VAS) leg pain score of ≥50 on a 100 mm scale; | • A primary and predominate diagnosis of discogenic back pain; • A primary and predominate diagnosis of facet-mediated back pain; • Back or non-radicular leg pain of unknown etiology; • Significant peripheral vascular disease-causing vascular claudication; • Significant peripheral neuropathy caused by conditions other than spinal stenosis; • History of fixed or permanent neurologic deficit related to spinal cord injury; • History of any previous surgery* at any level in the lumbosacral spine except for a discectomy or decompression; • History of any previous surgery* at the level(s) planned for treatment; *previous surgery includes spinal stimulator placement but does NOT include epidural injections, rhizotomy or nerve ablation • Isthmic spondylolisthesis or spondylolysis (pars fracture) at any level in the lumbar spine; • Clinically significant compromise of vertebrae at L1 to S1 levels due to osteoporotic vertebral compression fracture or any traumatic, neoplastic, metabolic or infectious pathology or congenital abnormality; • Spinous process fracture(s) or other posterior element fracture(s) of the segment to be instrumented that would preclude secure fixation of the LimiFlex Dynamic Sagittal Tether Device to the spinous process; • Spinous process insufficiency or deformity that would preclude secure fixation of the LimiFlex Dynamic Sagittal Tether Device to the spinous process including spinous process length <10 mm from lamina to dorsal tip or other significant deformity due to trauma, or congenital abnormality such as spina bifida occulta at the planned  |

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|  Study Inclusion Criteria | Study Exclusion Criteria  |
| --- | --- |
|  *Leg pain includes hip and/or buttock pain on the same side
• A pre-operative Oswestry Disability Index (ODI) score ≥35 points on a 100-point scale;
• Candidate for surgical decompression at a single level or two contiguous levels, with stabilization at only one level between L1-S1;
• Posterior element anatomy is appropriate for interspinous fixation including prediction of presence of spinous processes of segment to be instrumented following decompression (investigational AND control groups) and a prediction of >50% of facet joints present following decompression (investigational group only);
• ≥25-80 years of age and skeletally mature;
• Patient has the necessary mental capacity to participate and is willing and able to participate in the study for the duration of the study follow-up and is able to comply with study requirements; and
• Patient is willing and able to provide Informed Consent for study participation. | instrumented level that would preclude secure fixation of the LimiFlex Dynamic Sagittal Tether Device to the spinous process;
• The estimated distance between the LimiFlex Dynamic Sagittal Tether Device strap attachment points (midpoint of the cranial edge of the cranial spinous process and the midpoint of the caudal edge of the caudal spinous process) is <30mm on pre-operative lateral standing radiographs at the segment to be instrumented;
• Degenerative lumbar scoliosis with a Cobb angle >10° at the affected motion segment;
• Symptomatic lumbar stenosis that is not amenable to a direct surgical decompression (i.e. patients with stenosis requiring indirect, interbody decompression)
• Ankylosed motion segment at the target operative level
• Severe osteoporosis, defined as history of fragility fracture and DXA bone mineral density T-score <-2.5 or QCT bone mineral density T-score < 80mg/cubic cm. History of a fragility fracture requires that a DXA scan or QCT scan is completed;
• Planned hip or knee replacement surgery, severe osteoarthritis or other musculoskeletal pathology of the hip or leg that could preclude reliable patient self-reporting assessment scales and/or that would likely progress to surgery during study period;
• Documented allergy to titanium or polyethylene;
• Active local or systemic infection;
• Receiving immunosuppressant or long-term steroid-therapy;
• Known history of bone metabolic disorder, including Paget’s disease, hyperparathyroidism, renal osteodystrophy, and osteomalacia;
• Disease or condition that would preclude accurate clinical evaluation of the safety  |

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|  Study Inclusion Criteria | Study Exclusion Criteria  |
| --- | --- |
|   | and effectiveness of the study treatment or any significant medical conditions which would place the patient at excessive risk for surgery, such as;
○ Severe rheumatoid arthritis or other surgery, such as:
○ Active hepatitis (viral or serum) or HIV positive
○ Unstable cardiac disease
○ Uncontrolled diabetes
○ Renal failure
○ Severe muscular, neural or vascular diseases that endanger the spinal column
○ Cauda equina syndrome
○ Severe neurologic disorders including paralysis
• Morbid obesity defined as BMI >40;
• Active malignancy or history of metastatic malignancy within the last five years;
• Women who are pregnant or are interested in becoming pregnant within the study period;
• Currently seeking or receiving worker’s compensation for back pain or spinal condition;
• Currently involved in spinal litigation that potentially is associated with secondary financial gain;
• Current involvement in a study of another investigational product for similar purpose;
• Demonstrates three or more Waddell’s Signs of Inorganic Behavior;
• Active treatment of major psychiatric condition, such as depression, anxiety disorder, bipolar disorder, schizophrenia, personality disorder, that could prevent accurate completion of self-reporting assessment scales;
• Current history (withing 12 months) of substance abuse; including alcohol abuse; or
• A prisoner.  |

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2. Follow-up Schedule

All subjects were expected to return for follow-up examinations at 6 weeks, and 3, 6, 12, and 24 months post-operatively. Demographics and medical history were collected pre-operatively. Pre-operatively and post-operatively, objective parameters measured during the study included obtaining x-rays, neurological assessments, Oswestry disability Index (ODI), Visual Analog Scale (VAS) scores for leg and back pain, Zurich Claudication Questionnaire (ZCQ), SF-12 Physical Component Score (PCS), SF-12 Mental Component Score (MCS), and medication use for pain, as reported in Table 5. Adverse events and complications were recorded at all visits.

The key timepoints are shown below in the tables summarizing safety and effectiveness.

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Table 5: Follow-Up Schedule

|  Event | Screening/ Baseline ≤ 2 months to surgery | Procedure | Post-Procedure @ Discharge | 6 Week ± 2 Weeks | 3 Month ± 2 Weeks | 6 Month ± 1 Month | Both Groups: 12, 24, 36, 48, & 60 Month ± 2 months | Unplanned Visit  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  CT myelogram or MRI | X^{R,1} |  |  |  |  |  |  |   |
|  Informed Consent | X^{R,2} |  |  |  |  |  |  |   |
|  Eligibility Criteria | X^{R} |  |  |  |  |  |  |   |
|  Pregnancy Test (premenopausal women) | X |  |  |  |  |  |  |   |
|  Radiographs
*Note: All radiographs are to be obtained in concordance with Radiographic Evaluation Protocol | X^{R, 4} |  | X^{3} | X^{5} | X^{6} | X^{7} | X^{4, 7} | As Necessary  |
|  Osteoporotic Self-Assessment Tool (OST) | X |  |  |  |  |  |  |   |
|  DXA or QCT scan (only required if patient has history of fragility fracture) | X |  |  |  |  |  |  |   |
|  Physical/Neuro Exam | X^{R} |  | X | X | X | X | X | X  |
|  Physical/Medical Therapy | X |  | X | X | X | X | X | X  |
|  Medication Use for Pain |  |  | X | X | X | X | X | X  |
|  VAS Pain Scale (leg and back) |  |  |  | X | X | X | X |   |
|  Zurich Claudication Questionnaire |  |  |  | X | X | X | X |   |

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|  Event | Screening/ Baseline ≤ 2 months to surgery | Procedure | Post-Procedure @ Discharge | 6 Week ± 2 Weeks | 3 Month ± 2 Weeks | 6 Month ± 1 Month | Both Groups: 12, 24, 36, 48, & 60 Month ± 2 months | Unplanned Visit  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Oswestry Disability Index |  |  |  | X | X | X | X |   |
|  SF-12 |  |  |  | X | X | X | X |   |
|  Intra-operative Data |  | X |  | X | X | X | X |   |
|  Days to Return to Work |  |  |  | X | X | X | X |   |
|  Patient Satisfaction |  |  |  | X | X | X | X |   |
|  Adverse Events |  | X | X | X | X | X | X | X  |
|  Device/Procedure Observations |  | X |  |  |  |  |  |   |

R: Minimum required data for RCS or historical control subject (HCS) eligibility
1: MRI or CT Myelogram within 12 months prior to procedure is acceptable if documented that symptoms are stable
2: Informed consent requirements for RCS determined by site’s governing IRB or ethics committee.
3: If patient safety/comfort precludes standing films for patients being discharged same-day, the option is to take radiographs in a supine position or with fluoroscopy at closure.
4: AP &amp; lateral, flexion and extension (within 4 months prior to surgery)
5: AP &amp; Lateral
6: Both Groups: AP + lateral Required for Investigational Group &amp; Optional for Control Group: flexion and extension
7: AP &amp; lateral, flexion and extension

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PMA P220031: FDA Summary of Safety and Effectiveness Data

3. Clinical Endpoints

The safety of the LimiFlex Dynamic Sagittal Tether was assessed by comparison to the control group with respect to nature and frequency of adverse events (overall and in terms of severity and relationship to the implant), subsequent index level surgical procedures, and maintenance of neurological status. The sponsor gathered all AE data and had all safety data adjudicated by an independent CEC.

The effectiveness of the LimiFlex Dynamic Sagittal Tether was assessed by comparison to the control group with respect to a primary endpoint, as described below. Effectiveness was further evaluated by assessing the individual elements of the primary endpoint including improvement in VAS, ZCQ, SF-12, patient satisfaction, and other clinical and life parameters. Similar criteria were used to measure success in both groups.

Study success was based on the hypothesis that treatment with the LimiFlex Dynamic Sagittal Tether is non-inferior to the fusion control in achieving Month 24 composite clinical success (CCS). More specifically, the primary study hypothesis is that the probability of clinical success at Month 24 for subjects implanted with the LimiFlex Dynamic Sagittal Tether following decompression is within a non-inferiority delta of the probability of clinical success at Month 24 for subjects receiving TLIF with concomitant posterolateral instrumented fusion (PLF) following decompression. The null and alternative hypotheses are:

H₀: Pₜᵢvestigational – P_Fusion ≤ –0.125
Hₐ: Pₜᵢvestigational – P_Fusion &gt; –0.125

With regard to success/failure criteria, each subject was evaluated per the primary composite endpoint as described below.

Primary Endpoint

The primary endpoint was a composite endpoint which required a subject meet all the following criteria to be considered a clinical success:

- Improvement of at least 15 points (100-point scale) on ODI at Month 24 compared to baseline
- Absence of a decrease in neurologic status (motor or sensory) at Month 24 compared to baseline, unless attributable to a concurrent medical condition or other cause unrelated to the device and/or study procedure
- Absence of additional surgical intervention, defined as revision, removal, reoperation or supplemental fixation/fusion*, in a separate surgery subsequent to the index procedure, at the instrumented level or levels adjacent to the instrumented level, over the initial 24 months post-treatment
- Absence of device integrity failures, defined as device breakage, device separation or disassembly, or device dislocation over the initial 24 months post-treatment

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*The following definitions were used for Additional Surgical Intervention, based upon the FDA Guidance Document for the Preparation of IDEs for Spinal Systems (https://www.fda.gov/media/71777/download):

- Revision – procedure that adjusts or in any way modifies or removes part of the original implant system, with or without replacement of a component; or a procedure in which the original implant system is removed followed by replacement of the entire system. A revision may also include adjusting the position of the original implant system.
- Removal – procedure in which all of the original implant system is removed without replacement.
- Reoperation – any surgical procedure at the instrumented level or levels adjacent to the instrumented level that does not remove, modify, or add any implant components to the system.
- Supplemental fixation/fusion – procedure in which additional instrumentation is implanted at the instrumented level or levels adjacent to the instrumented level.

## Secondary Endpoints

Subjects in each treatment arm were evaluated on the following Secondary Endpoints:

- Each of the individual components of the primary endpoint described above
- Estimated blood loss and units of blood transfused
- Length of procedure (skin to skin)
- Hospital stay
- Length of time for a subject to return to their normal activities of daily living
- Work status and days to return to work (as appropriate)
- Medication use for pain, including narcotic, usage
- VAS leg pain
- VAS back pain
- ZCQ
- SF-12 Health Survey to assess quality of life
- Treatment satisfaction
- Radiographic – Radiographic evidence demonstrating the absence of spontaneous fusion in those treated with the investigational device, and radiographic evidence demonstrating fusion in those treated with TLIF with concomitant PLF with pedicle screw instrumentation at Month 24

## Clinical Events Committee and Data and Safety Monitoring Board

A CEC was utilized to mitigate reporting bias of safety-related events. The CEC was comprised of three (3) independent spine surgeons, and a CEC charter was used to define the role of the CEC. The CEC reviewed all Serious Adverse Events (SAEs), all device- or procedure-related AEs, and all spinous process fracture AEs to confirm or re-classify the event term, seriousness, severity, and relationship to study device, procedure or other. For events determined to be SAEs, the CEC reviewed for the potential to re-classify the event

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as an Unanticipated Adverse Device Effect (UADE) or not an UADE. The CEC reviewed all cases of spinous process fracture to assess severity, causality and clinical significance. The CEC reviewed neurologic data in all cases of decline at Month 24 compared to baseline to determine if it met the primary endpoint failure criteria. Lastly, protocol deviations were reviewed and classified as 'major' or 'minor' per the definitions in the CEC Charter.

The purpose of the DSMB was to safeguard study participants' interests and monitor the overall conduct of the clinical trial. The DSMB met periodically upon completion of each interim safety analysis, or as needed, to review the cumulative results of the study and to evaluate any safety or efficacy issues that may arise during the course of the study. The DSMB reviewed all data used to conduct the Interim Safety Analyses for the LimiFlex Dynamic Sagittal Tether related to spinous process fractures and found that the incidence of spinous process fractures did not reach the modified Stopping Rule safety boundary.

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B. Accountability of PMA Cohort

At the time of database lock, a total of 299 subjects (140 investigational and 159 control) were enrolled in the IDE study. Nineteen (19) control arm subjects were excluded per FDA request, and the remaining 280 subjects were assessed via the PS subclassification sequential modeling process. One-hundred and forty (140) investigational subjects and one-hundred and twenty-three (123) control subjects were PS-selected, comprising the primary “ITT-PS” analysis set, as described below. Of the 263 subjects in the primary ITT-PS analysis set, 85.9% (226/263) were evaluable for the primary endpoint at Month 24 (89.3% (125/140) investigational; 82.1% (101/123) control). Analysis sets specified in the study protocol were defined as follows:

(1) ITT – PS Selected Analysis Set: The ITT – PS Selected analysis set included all subjects assigned to either the investigational or control groups in which treatment was attempted as defined by the recording of incision time, with the exception of subjects for which no study device implantation was attempted due to violation of inclusion or exclusion criteria identified intra-operatively that could not reasonably be assessed prior to surgery (i.e., intra-operative screening failures). Subjects were classified by the group in which they were assigned, regardless of whether or not that treatment was actually completed. Intra-operative failures were included in primary non-inferiority testing as composite clinical endpoint failures. Analyses of the primary endpoint were conducted using the ITT – PS Selected analysis set. A subject must have been selected into a PS subclass in order to be included in analyses. The PS subclassification procedure was designed to retain all subjects receiving the investigational device, if possible. Since selection into a PS subclass is the observational study equivalent to randomization in a randomized study, control subjects not selected into a PS subclass were not to be included in the ITT – PS analysis set, and not included in the primary effectiveness and safety analyses.

(2) Safety Analysis Set: The Safety analysis set definition included all subjects in the ITT – PS Selected analysis set, and any investigational device subjects who were not selected into a PS subclass. As all investigational subjects were selected into a PS subclass, the Safety analysis set and ITT-PS Selected analysis set represent the same set of subjects. Subjects were classified according to the treatment actually received. Primary safety analyses were conducted using the SA set.

(3) Per-Protocol (PP) Analysis Set: The PP analysis set included subjects in the ITT – PS Selected analysis set with no major protocol violations of inclusion or exclusion criteria, as determined by the CEC and who were evaluable for the Month 24 primary endpoint. It also excluded subjects with confounding medical events or treatments following index surgery that are expected to bias determination of the primary endpoint, as determined by the CEC. Secondary endpoint analyses were conducted using the PP analysis set.

(4) Screen Failure Analysis Set: The Screen Failure analysis set included all subjects consented who did not satisfy or meet inclusion and exclusion criteria, and/or in whom treatment was not attempted. Please note, these subjects were not followed after surgery and were not included in the ITT – PS Selected analysis set, with the exception of the RCS screen fail patients who received low-dose BMP (“X Small”

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kit), but otherwise met all inclusion/ exclusion criteria, and were followed after surgery.

Subject accounting is presented in Table 6 with "I" representing the investigational group, and "C" representing the control group. Accounting information is also presented graphically via a subject accounting tree in Figure 3 below.

The number of subjects available for certain evaluations in the table below may differ from the actual number of subjects evaluated at Month 24 follow-up. At Month 24,  $89.3\%$  (125/140) of investigational subjects and  $82.1\%$  (101/123) of control subjects were evaluated with for CCS. Nine (9) subjects had Month 24 assessments prior to the start of their follow-up window. Of these, eight (8) were within 2 months of their visit window, and one was evaluated for the Month 24 visit 203 days prior to their follow-up window.

Table 6: Accounting and Follow-up Information

|   | Pre-Op |   | Month 12 |   | Month 24  |   |
| --- | --- | --- | --- | --- | --- | --- |
|   |  I | C | I | C | I | C  |
|  [1] Theoretical due (TD) | 140 | 123 | 140 | 123 | 140 | 123  |
|  [2] Not implanted | 0 | 0 | 2 | 4 | 2 | 4  |
|  [3] Cumulative deaths | 0 | 0 | 0 | 0 | 0 | 1  |
|  [4] Cumulative SSIs at index or adjacent level at end of interval | 0 | 0 | 6 | 4 | 10 | 13  |
|  [5] Not Yet Overdue | 0 | 0 | 0 | 0 | 0 | 0  |
|  [6] (Deaths + SSIs) among theoretically due | 0 | 0 | 6 | 4 | 10 | 13  |
|  [7] Expected due for clinic visit = [1] - [2] - [5] - [6] | 140 | 123 | 132 | 115 | 128 | 106  |
|  [7a] Adding subjects with observed clinical data prior to SSI in interval to denominator | 140 | 123 | 133 | 115 | 129 | 107  |
|  [8] SSIs among theoretically due | 0 | 0 | 6 | 4 | 10 | 13  |
|  [9] Expected due + SSI's + Not implanted among TD = [7] + [8] + [2] | 140 | 123 | 140 | 123 | 140 | 123  |

All Evaluated Accounting [Actual] Among Expected Due Procedures

|  [10] # of procedures with any completed patient reported outcomes | 140 | 123 | 130 | 99 | 125 | 88  |
| --- | --- | --- | --- | --- | --- | --- |
|  [11] All Evaluated Visit Compliance [%] = [10] / [7a] | 100% | 100% | 97.7% | 86.1% | 96.9% | 82.2%  |
|  [12] ODI Responder status (censored for SSI) | 140 | 123 | 130 | 99 | 125 | 87  |
|  [13] Neurological Status [Motor and Sensory] |  |  |  |  | 120 | 95  |
|  [14] Device integrity (censored for SSI) |  |  |  |  | 114 | 88  |
|  [15] Composite clinical success (CCS) |  |  |  |  | 125 | 101  |
|  [16] Actual% Follow-up for CCS [16] = [15] / [9] |  |  |  |  | 89.3% | 82.1%  |

Within Window Accounting [Actual] Among Expected Due

|  [17] ODI Responder status determined Clinical visit within window |  |  |  |  | 109 | 71  |
| --- | --- | --- | --- | --- | --- | --- |
|  [18] Within window compliance [18] =[17]/[7a] |  |  |  |  | 84.5% | 66.4%  |
|  [19] Neurological Status [Motor and Sensory] |  |  |  |  | 102 | 73  |
|  [20] Device integrity |  |  |  |  | 99 | 66  |

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|   | Pre-Op |   | Month 12 |   | Month 24  |   |
| --- | --- | --- | --- | --- | --- | --- |
|   |  I | C | I | C | I | C  |
|  [21] Composite clinical success (CCS) (Clinical visit within window) |  |  |  |  | 107 | 83  |
|  [22] Actual% Follow-up for CCS [22] = [21] / [9] |  |  |  |  | 76.4% | 67.5%  |

# Notes for Accounting and Follow-up Table

[1] Theoretically due: The number of subjects that would have been examined if all patients returned on the exact surgical anniversary within the respective visit window. Visit windows were +/-60 days at month 12 and month 24; +/- 30 days at month 6; and +/- 14 days for month 3 and week 6.
[2] Not implanted: Subjects for which surgery began but the intended device was not implanted.
(3) Cumulative deaths: Cumulative deaths up to the date of the exact anniversary defining the current interval. Deaths occurring after the exact anniversary are recorded in the next interval. Note: One additional death in a Investigational subject occurred after the exact anniversary of Month 36 and so is not included in this table.
[4] Cumulative SSIs at index or adjacent level at end of interval: Additional surgical intervention, defined as revision, removal, reoperation or supplemental fixation/fusion in a separate surgery subsequent to the index procedure at the instrumented level or levels adjacent to the instrumented level. This row includes all subsequent surgical interventions (SSIs) whether theoretically due or not. Note: The number of cumulative SSI's is up to end of interval to match CCS analysis. There was one SSI at day 747 in LimiFlex and 2 SSI's at Days 742 and 750 among controls that occurred after Day 730 but prior to end-of-interval, Day 790.
(5) Not Yet Overdue: Subjects in this category are those who were a) theoretically due; and b) within the evaluation time window and were not counted as a theoretically due death or revision, but had not yet been evaluated at the time of data lock.
[6] Deaths + SSIs among theoretical due: This row records the number of patients experiencing either death or SSI (index or adjacent level) among theoretically up to the date of the exact anniversary defining the current interval.
[7] Expected due for clinic visit  $[7] = [1] - [2] - [5] - [6]$ : Row [7] computes Expected due based on interval counts. Expected due for clinic visit is equal to Theoretical due (row [1]) minus Not Implanted (row [2]) minus Not yet overdue (row [5]) minus cumulative deaths and SSIs among the theoretically due (row [6]).
[7a] Adding subjects with observed clinical data prior to SSI in interval to denominator: There are 5 instances in which ODI was evaluated in the same interval as an SSI, but earlier in the interval. Only patient reported outcomes (PROs) subsequent to SSI are censored. PROs obtained prior to an SSI reflect impact of the index surgery and so are not censored. These values are included in data summary tables. Therefore, in order to include all subjects with potentially observed data in the denominators of visit compliance, row [7a] adds these subjects back to the denominator. The five cases in which row [7] and row [7a] are identified by bold font. The following summarizes the five specific cases.
There are two subjects, one in each group that had Month 24 clinical evaluation of ODI prior to an SSI. These two subjects are added to row [7] to determine row [7a] since their pre SSI values are available. Thus, the counts in row [7a] are 129 instead of 128 and 107 instead of 106. Investigational 08-006-BHS had ODI recorded on Day 726 and had SSI on Day 747. Control 12-014-JEG had ODI recorded on Day 696 and had SSI on Day 742. There were 3 other such cases prior to Month 24. Investigational 08-030-DEM had a clinic visit before an SSI on Day 418 in the Month 12 interval, Control 12-010-JLB had a clinic visit before an SSI on Day 208 in the Month 6 interval, and Control subject 21-014-MDS had a clinic visit before an SSI on Day 54 in the Week 6 interval. These three subjects are also added to row [7] to determine row [7a] since their pre SSI values are available.
[8] SSIs among theoretical due: SSIs among theoretically due are the count of theoretically due SSIs. Note that these SSIs are added back to the expected due count in order for row [9] to serve as the correct denominator for the overall success outcomes calculated in row [15] and row [21].
[9] Expected due and SSI's among theoretical due  $[7] + [8] + [2]$ : Expected due plus theoretically due SSIs is computed by adding expected due in row [7] to the number of cumulative SSIs among theoretical procedures in row [8] to the number of Not Implanted. This row serves as the denominator for overall success outcomes since overall success status is known to be failure for those with SSI.

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[10] # of procedures with any completed patient reported outcomes: This row provides the number of subjects among those included in row [7] with any completed patient reported outcome (i.e., ODI, ZCQ, VAS, PCS, MCS) among expected due.

[11] All Evaluated Visit Compliance [%] [11] = [10] / [7a]: All Evaluated Visit Compliance (%) is computed as number of subjects with any clinical data in the specified interval row [10] expressed as a percentage of row [7a]. The exception is at baseline, where [11] = [10] / [9] in order to capture visit compliance including non-implanted. All evaluated compliance is based on the presence of any clinical data, even if incomplete, and demonstrates that the procedure was actively followed at least up to the specific interval.

[12] ODI Responder status determined: This is the count of subjects with ODI responder status determined among patients in row [7a]. Note: clinical scores, including ODI, are censored at the time of SSI. That is, among those with an SSI, ODI scores are not 'expected due' for the purpose of determining ODI follow-up compliance.

[13] Neurological Status [Motor and Sensory]: This row is the count of procedures for which the primary neurological endpoint used in CCS is evaluable. Neurological test results are not censored for SSI.

[14] Device integrity: This row is the count of procedures with evaluable device condition endpoint used in the CCS. Device integrity is censored for SSI.

[15] Composite clinical success (CCS): This row is the count of patients evaluable for the primary endpoint, Month 24 composite clinical success (CCS).

[16] Actual % Follow-up for CCS [16] = [15] / [9]: The number of procedures with evaluable overall success is taken from row [15] while the denominator is taken from row [9].

[17] ODI Responder status determined: This row is the count of subjects with ODI responder status obtained within the protocol-defined visit window.

[18] Within Window Visit ODI Compliance [%] [18] = [17] / [7a]: Within Window Visit ODI Compliance (%) is computed as number of subjects with the ODI component of the CCS measured within the interval. This row expresses row [18] as a percentage of expected due row [7].

[19] Neurological status determined: This row is the count of subjects with Neurological responder status obtained within the visit window.

[20] Device Integrity status determined: This row is the count of subjects with radiographic imaging used to determine Device Integrity status obtained within the visit window.

[21] Composite clinical success (CCS) Within Window: This row is the count of patients evaluable for the primary endpoint, Month 24 composite clinical success (CCS) within the visit window. Subjects that are CCS successes must have all components within-window. For subjects that are CCS failures, the component(s) defining failure must be within window except for terminal failures (Implanted, SSI, Device Integrity), where a subject failing any of these components prior to the end of the Month 24 window is considered to have CCS within window.

[22] Actual% Follow-up for CCS [22] = [21] / [9]: The number of subjects with evaluable overall success is taken from row [21] while the denominator is taken from row [9]. Within window follow-up was significantly impacted by the extenuating circumstances presented by the COVID-19 Public Health Emergency overlapping the Month 24 visits when sites were delaying or cancelling elective surgeries and nonessential research related patient visits to healthcare facilities and limited access to clinical monitors. Of the 263 ITT-PS selected subjects, 94.3% (248/263) were due for their Month 24 visit during the COVID-19 Public Health Emergency.

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![img-2.jpeg](img-2.jpeg)
Figure 3: Subject Accounting Tree

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# C. Study Population Demographics and Baseline Parameters

The tables below provide a summary of pre-operative and demographic variables for investigational and control subjects in ITT-PS analysis set. Table 7 presents age, height, weight and BMI, stratified by treatment group and gender, as well as baseline functional scores. The  $95\%$  confidence intervals for group differences adjusted for PS subclass demonstrate no statistical evidence of a group difference in any of the demographic or baseline functional status continuous variables. Table 8 identifies gender, ethnicity and race demographics of investigational and control subjects.

Table 7: Summary of Baseline and Demographic Continuous Variables ITT-PS Analysis Set

|   | Investigational |   |   |   |   |   | Controls |   |   |   |   |   | Investigational - Controls1  |   |   |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Demographics - All | N | Mean | SD | Med | Min | Max | N | Mean | SD | Med | Min | Max | Diff | LB | UB  |
|  Age at surgery (yrs) | 140 | 65.8 | 7.7 | 66.1 | 47.4 | 80.0 | 123 | 64.6 | 8.9 | 64.8 | 31.5 | 80.7 | 0.61 | -2.53 | 3.75  |
|  Height (cm) | 140 | 169.1 | 10.2 | 167.6 | 147.3 | 198.1 | 123 | 165.8 | 9.7 | 164.6 | 133.4 | 193.0 | 0.38 | -2.62 | 3.37  |
|  Weight (kg) | 140 | 80.7 | 17.1 | 77.8 | 46.3 | 133.8 | 123 | 80.6 | 17.2 | 80.3 | 42.6 | 133.8 | 0.75 | -5.24 | 6.74  |
|  BMI (k/m2) | 140 | 28.1 | 4.7 | 27.2 | 17.4 | 39.1 | 123 | 29.2 | 5.2 | 28.9 | 18.3 | 42.5 | 0.15 | -1.42 | 1.73  |
|  Osteo Self Assessment Test | 140 | 2.99 | 3.97 | 2.56 | -6.1 | 13.6 | 123 | 3.21 | 4.12 | 3.14 | -7.6 | 17.6 | 0.03 | -1.37 | 1.43  |
|  Demographics - Male | N | Mean | SD | Med | Min | Max | N | Mean | SD | Med | Min | Max | Diff | LB | UB  |
|  Age at surgery (yrs) | 59 | 66.6 | 7.1 | 67.9 | 48.0 | 80.0 | 37 | 66.8 | 7.7 | 68.0 | 48.0 | 80.1 | -2.22 | -9.00 | 4.55  |
|  Height (cm) | 59 | 178.2 | 6.9 | 180.3 | 162.6 | 198.1 | 37 | 176.7 | 7.2 | 177.3 | 162.6 | 193.0 | 1.09 | -1.46 | 3.65  |
|  Weight (kg) | 59 | 89.5 | 16.5 | 87.8 | 56.7 | 133.8 | 37 | 92.9 | 14.1 | 90.7 | 72.6 | 133.8 | -2.75 | -8.03 | 2.53  |
|  BMI (k/m2) | 59 | 28.0 | 4.0 | 27.4 | 20.2 | 36.5 | 37 | 29.7 | 3.7 | 30.4 | 23.0 | 37.9 | -1.35 | -2.74 | 0.04  |
|  Osteo Self Assessment Test | 59 | 4.58 | 3.80 | 4.11 | -3.7 | 13.6 | 37 | 5.23 | 3.45 | 4.49 | -0.6 | 14.7 | -0.11 | -1.93 | 1.72  |
|  Demographic - Female | N | Mean | SD | Med | Min | Max | N | Mean | SD | Med | Min | Max | Diff | LB | UB  |
|  Age at surgery (yrs) | 81 | 65.2 | 8.1 | 65.5 | 47.4 | 80.0 | 86 | 63.6 | 9.3 | 64.5 | 31.5 | 80.7 | 1.46 | -1.91 | 4.82  |
|  Height (cm) | 81 | 162.6 | 6.4 | 162.6 | 147.3 | 175.3 | 86 | 161.2 | 6.2 | 162.6 | 133.4 | 176.5 | -0.70 | -3.36 | 1.95  |
|  Weight (kg) | 81 | 74.3 | 14.7 | 72.1 | 46.3 | 109.8 | 86 | 75.3 | 15.6 | 74.8 | 42.6 | 119.5 | 1.08 | -4.87 | 7.04  |
|  BMI (k/m2) | 81 | 28.1 | 5.2 | 26.2 | 17.4 | 39.1 | 86 | 29.0 | 5.8 | 28.4 | 18.3 | 42.5 | 0.63 | -1.21 | 2.47  |
|  Osteo Self Assessment Test | 81 | 1.83 | 3.69 | 1.50 | -6.1 | 10.4 | 86 | 2.34 | 4.10 | 2.15 | -7.6 | 17.6 | -0.07 | -1.64 | 1.49  |
|  Baseline Functional Status | N | Mean | SD | Med | Min | Max | N | Mean | SD | Med | Min | Max | Diff | LB | UB  |
|  Oswestry Disability Index (ODI) | 140 | 52.6 | 11.9 | 51.5 | 22.0 | 84.0 | 123 | 51.6 | 13.5 | 47.0 | 32.0 | 92.0 | 1.14 | -3.11 | 5.39  |
|  VAS Back Pain | 140 | 67.4 | 23.9 | 73.5 | 0.0 | 99.0 | 122 | 68.3 | 23.0 | 73.0 | 0.0 | 100.0 | -1.46 | -8.39 | 5.47  |
|  VAS Worse Leg Pain | 140 | 78.8 | 13.2 | 81.0 | 22.0 | 100.0 | 111 | 78.7 | 15.9 | 80.0 | 31.0 | 100.0 | -2.32 | -6.51 | 1.88  |
|  VAS Left Leg Pain | 140 | 61.7 | 28.6 | 71.5 | 0.0 | 97.0 | 109 | 57.1 | 31.1 | 62.0 | 0.0 | 100.0 | 3.19 | -6.48 | 12.85  |
|  VAS Right Leg Pain | 140 | 65.7 | 27.2 | 75.0 | 0.0 | 100.0 | 110 | 59.1 | 32.3 | 66.5 | 0.0 | 100.0 | 5.43 | -5.32 | 16.17  |
|  ZCQ Severity Score | 139 | 3.54 | 0.53 | 3.57 | 2.00 | 4.86 | 94 | 3.47 | 0.58 | 3.43 | 2.14 | 5.00 | 0.05 | -0.17 | 0.27  |
|  ZCQ Physical Score | 139 | 2.75 | 0.44 | 2.80 | 1.40 | 3.60 | 94 | 2.78 | 0.50 | 2.80 | 1.00 | 4.00 | -0.10 | -0.24 | 0.03  |
|  Notes:1 ATTPS subclass weighted device group differences and 95% confidence intervals (CI) for group differences.  |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |

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Table 8: Summary of Baseline and Demographic Categorical Variables PS Selected Analysis Set

|   | Investigational |   |   | Controls |   |   | Investigational - Controls1  |   |   |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|   | N | n | % (n/N) | N | n | % (n/N) | Diff (%) | LB | UB  |
|  Males | 140 | 59 | 42.1% | 123 | 37 | 30.1% | 5.3% | -9.9% | 20.6%  |
|  Females | 140 | 81 | 57.9% | 123 | 86 | 69.9% |  |  |   |
|  Ethnicity | N | n | % | N | n | % | Diff (%) | LB | UB  |
|  Hispanic or Latino | 140 | 13 | 9.3% | 123 | 10 | 8.1% | 4.1% | -1.8% | 10.1%  |
|  Not Hispanic or Latino | 140 | 127 | 90.7% | 123 | 113 | 91.9% |  |  |   |
|  Race | N | n | % | N | n | % | Diff (%) | LB | UB  |
|  White | 140 | 121 | 86.4% | 123 | 113 | 91.9% | -3.8% | -14.7% | 7.1%  |
|  Asian | 140 | 10 | 7.1% | 123 | 4 | 3.3% |  |  |   |
|  Black | 140 | 2 | 1.4% | 123 | 6 | 4.9% |  |  |   |
|  Other | 140 | 7 | 5.0% | 123 | 0 | 0.0% |  |  |   |
|  Notes:1 ATT PS subclass weighted device group differences and 95% confidence intervals (CI) for group differences.  |   |   |   |   |   |   |   |   |   |

Index level of surgery was also recorded in this clinical trial. In the investigational group, surgery occurred at: L2-L3 - 0.7% (1/140); L3-L4 - 14.3% (20/140); and L4-L5 - 85% (119/140). In the control group, surgery occurred at: L2-L3 - 1.6% (2/123); L3-L4 - 6.5% (8/123); L4-L5 - 87% (107/123); and L5-S1 - 4.9% (6/123). A total of 20.0% (28/140) of the investigational cohort and 19.5% (24/123) of the control cohort underwent adjacent level decompression. In this clinical trial, only 2 control subjects required a transfusion during their surgery.

Additionally, baseline history of spinal diagnoses was collected. All investigational and control subjects were diagnosed with degenerative spondylolisthesis. In the investigational group, 54.3% (76/140) of subjects were also diagnosed with degenerative disc disease, and 2.9% (4/140) were identified as having a vertebral compression fracture. In the control group, 64.2% (79/123) of subjects were also diagnosed with degenerative disc disease, and 0.8% (1/123) were identified as having a vertebral compression fracture. A total of 9.3% (13/140) of investigational subjects and 15.4% (19/123) of control subjects had other diagnoses, including but not limited to spinal stenosis, radiculopathy, annular tears, and disc herniation.

Details on lumbar spinal stenosis type and severity are shared in Table 9 below. The severity of stenosis was predominantly recorded as moderate in both investigational and control subjects. Over half of subjects in both groups were reported to have foraminal stenosis.

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Table 9: Lumbar Spinal Stenosis Type and Severity

|   | Investigational (N=140) |   |   | Controls (N=123)  |   |   |
| --- | --- | --- | --- | --- | --- | --- |
|  Lumbar Spinal Stenosis Characterization |  |   |   |   |   |   |
|  Central Canal Stenosis Severity | N | n | % (n/N) | N | n | % (n/N)  |
|  Mild | 140 | 0 | 0.0 | 122 | 1 | 0.8  |
|  Moderate | 140 | 87 | 62.1 | 122 | 72 | 59.0  |
|  Severe | 140 | 53 | 37.9 | 122 | 47 | 38.5  |
|  None | 140 | 0 | 0.0 | 122 | 2 | 1.6  |
|  N/A1 |  |  |  |  | 1 |   |
|  Right Lateral Recess Stenosis Severity | N | n | % | N | n | %  |
|  Mild | 140 | 4 | 2.9 | 122 | 8 | 6.6  |
|  Moderate | 140 | 74 | 52.9 | 122 | 43 | 35.2  |
|  Severe | 140 | 41 | 29.3 | 122 | 45 | 36.9  |
|  None | 140 | 21 | 15.0 | 122 | 26 | 21.3  |
|  N/A |  |  |  |  | 1 |   |
|  Left Lateral Recess Stenosis Severity | N | n | % | N | n | %  |
|  Mild | 140 | 11 | 7.9 | 122 | 7 | 5.7  |
|  Moderate | 140 | 69 | 49.3 | 122 | 44 | 36.1  |
|  Severe | 140 | 41 | 29.3 | 122 | 45 | 36.9  |
|  None | 140 | 19 | 13.6 | 122 | 26 | 21.3  |
|  N/A |  |  |  |  | 1 |   |
|  Right Foraminal Stenosis | N | n | % | N | n | %  |
|  Yes | 140 | 82 | 58.6 | 122 | 94 | 77.0  |
|  No | 140 | 58 | 41.4 | 122 | 28 | 23.0  |
|  N/A |  |  |  |  | 1 |   |
|  Left Foraminal Stenosis | N | n | % | N | n | %  |
|  Yes | 140 | 82 | 58.6 | 122 | 90 | 73.8  |
|  No | 140 | 58 | 41.4 | 122 | 32 | 26.2  |
|  N/A |  |  |  |  | 1 |   |
|  Notes: 1 N/A = Not currently available  |   |   |   |   |   |   |

Lastly, data on disc herniation morphology and location were collected. In the investigational group,  $14.3\%$  (19/133) of subjects were reported to have a disc protrusion, and  $39.1\%$  (52/133) were reported to have a disc extrusion. In the control group,  $4.5\%$  (5/111) of subjects were reported to have a disc protrusion, and  $29.7\%$  (33/111) were reported to have a disc extrusion. The location of disc herniation is reported in medial and lateral locations across both treatment groups.

The demographics of the study population are typical for a lumbar spine study performed in the US. A comparison of the treatment and control cohorts revealed no evidence of group differences in key demographic variables. This is expected, as the groups were PS matched to ensure balance across baseline covariates. The PS designed sample showed adequate covariate balance between the Investigational and Control treatment groups.

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D. Safety and Effectiveness Results

1. Safety Results

The analysis of safety was based on the investigational cohort of 140 LimiFlex Dynamic Sagittal Tether subjects and 123 PS-selected control subjects available through the Month 24 evaluation. AEs were reportable at any post-operative time as reported or during a scheduled study visit. The key safety outcomes for this study are presented below in Table 10 through Table 16. Adverse effects are reported in Table 11 through Table 15.

Adverse event definitions:

The following safety event definitions were used in this clinical trial:

- Adverse Event (AE) – an untoward medical occurrence in a subject that may or may not be considered device related. All AEs, regardless of relationship to the device, were recorded, as applicable, on the case report forms (CRF) provided. AEs that occurred during this study were treated by established standards of care which will protect the life and safety of the subjects.

- Serious Adverse Events (SAEs) – An AE was considered an SAE if it resulted in death or led to a serious deterioration in the health of the subject that:
a. resulted in a life-threatening illness or injury;
b. resulted in a permanent impairment of a body structure or a body function;
c. required in-patient hospitalization or prolongation of existing hospitalization;
d. resulted in medical or surgical intervention to prevent permanent impairment to body structure or a body function.

- Unanticipated Adverse Device Effect (UADE) – an UADE was defined as any serious adverse effect on health or safety, or any life-threatening problem or death, caused by, or associated with, a device, if that effect, problem, or death were not previously identified in nature, severity, or degree of incidence in the investigational plan, or any other unanticipated serious problem associated with a device that relates to the rights, safety, or welfare of subjects.

- AE Device- and Procedure-Relatedness:
a. Definite – The AE is clearly related to the investigational or control device or procedure;
b. Probable – The AE is likely related to the investigational or control device or procedure;
c. Possible – The AE may be related to the investigational or control device or procedure;
d. Not Related – The AE is clearly not related to the investigational or control device or procedure;
e. Unknown – Unable to determine the relationship based on all available information.

- AE Severity – The intensity of AEs was evaluated using the following criteria:
a. Mild – noticeable to the patient but does not interfere with routine activity;
b. Moderate – interferes with the patient’s routine activity but responds to symptomatic therapy or rest;

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c. Severe – significantly limits the patient's ability to perform routine activities despite symptomatic therapy.

## Role of the CEC

The CEC reviewed safety events, including AEs and secondary surgical interventions (SSIs), to allow for uniform resolution of study-related events and evaluations, and to eliminate any site-by-site variations in reporting. The classification of the CEC overrides that of the investigator. CEC adjudications have been applied to data in the following tables.

## Adverse Event Summary

Table 10 summarizes all AEs and rates for the ITT-PS Selected analysis set across both the investigational and control groups at the date of database lock. Overall, similar rates of AEs occurred in the investigational group (86.4% - 121/140) and control group (84.6% - 104/123). SAEs were numerically higher in the investigational group (34.3% - 48/140) as compared to the control group (31.7% - 39/123). The core lab reported 24 spinous process fractures in the investigational group. Lastly, SSIs were numerically lower in the investigational group (7.2% - 10/140) as compared to the control group (10.9% - 13/123).

Table 10: Adverse Event Summary (ITT-PS Selected analysis set)

|   | Investigational |   |   | Controls |   |   | Investigational - Control^{1}  |   |   |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|   | (N=140) |   |   | (N=123) |   |   |   |   |   |
|   | No. of Events | No. of Pts. (n) | % of Pts. (n/N) | No. of Events | No. of Pts. (n) | % of Pts. (n/N) | Diff | LB | UB  |
|  Adverse Events |   |   |   |   |   |   |  |  |   |
|  All | 465 | 121 | 86.4 | 436 | 104 | 84.6 | 1.9 | -6.7 | 10.4  |
|  Device Related | 50 | 43 | 30.7 | 40 | 32 | 26.0 | 4.7 | -6.2 | 15.6  |
|  Procedure Related | 82 | 61 | 43.6 | 109 | 63 | 51.2 | -7.6 | -19.7 | 4.4  |
|  Serious Adverse Events |   |   |   |   |   |   |  |  |   |
|  All | 60 | 48 | 34.3 | 64 | 39 | 31.7 | 2.6 | -8.8 | 14.0  |
|  Device Related | 16 | 16 | 11.4 | 16 | 16 | 13.0 | -1.6 | -9.5 | 6.4  |
|  Procedure Related | 28 | 26 | 18.6 | 30 | 23 | 18.7 | -0.1 | -9.6 | 9.3  |
|  Spinous Process Fracture |  | 24 | 17.1 | - | - | - | - | - | -  |
|  Secondary Surgical Intervention^{2} |  | 10 | 7.2 |  | 13 | 10.9 | -3.7 | -10.8 | 3.4  |
|  Death |  | 0 | 0.0 |  | 1 | 0.8 | - | - | -  |
|  Notes:
1 95% binomial confidence interval without PS adjustment.
2 Includes secondary surgical interventions occurring on or before 790 days post index surgery. The denominators for the SSI row excludes 2 Investigational not-implanted and 4 Controls not-implanted.  |   |   |   |   |   |   |   |   |   |

## All Adverse Events

Table 11 and Table 12 identifies all AEs reported as of the database lock by AE term, with the number of subjects experiencing the events. Percentages are calculated as the number of subjects experiencing an event divided by the number of subjects treated in the ITT-PS Selected analysis set. The investigational group presented with 465 events

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occurring in 86.4% (121/140) of subjects, compared to 436 events occurring in 84.6% (104/123) of control subjects.

The most common AEs by rate reported in the investigational group were: new/increased back pain (24.3% - 34/140); new/increased leg pain (21.4% - 30/140); and, other disorders of the musculoskeletal system (21.4% - 30/140). In the control group, the most common AEs by rate were: new/increased back pain (22.0% - 27/123); and, new/increased musculoskeletal pain, other (26.0% - 32/123).

Please note that the following safety tables may include AE codes 'Spinuous process fracture affecting device fixation' and/or 'Spinuous process fracture, specify displaced or non-displaced.' These AE codes include spinuous process fractures reported by the clinical site only.

Table 11: All Adverse Events (ITT-PS Selected analysis set)

|   | Investigational (I) (N=140) |   |   | Controls (C) (N=123) |   |   | I vs C1  |   |   |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Specific Adverse Event | No. of Events | No. of Pts. (n) | % of Pts. (n/N) | No. of Events | No. of Pts. (n) | % of Pts. (n/N) | Diff | LB | UB  |
|  New/increase back pain | 41 | 34 | 24.3 | 29 | 27 | 22.0 | 2.3 | -7.9 | 12.5  |
|  New/increased leg pain | 37 | 30 | 21.4 | 13 | 12 | 9.8 | 11.7 | 3.1 | 20.3  |
|  Other disorder of musculoskeletal system | 36 | 30 | 21.4 | 23 | 18 | 14.6 | 6.8 | -2.4 | 16.0  |
|  Radiculopathy | 29 | 27 | 19.3 | 25 | 23 | 18.7 | 0.6 | -8.9 | 10.1  |
|  New/increased musculoskeletal pain, other | 37 | 26 | 18.6 | 46 | 32 | 26.0 | -7.4 | -17.5 | 2.6  |
|  Other | 25 | 21 | 15.0 | 26 | 19 | 15.4 | -0.4 | -9.2 | 8.3  |
|  Numbness/tingling | 17 | 16 | 11.4 | 21 | 16 | 13.0 | -1.6 | -9.5 | 6.4  |
|  Osteoarthritis, Hip | 11 | 11 | 7.9 | 7 | 6 | 4.9 | 3.0 | -2.9 | 8.8  |
|  Fracture | 11 | 10 | 7.1 | 2 | 2 | 1.6 | 5.5 | 0.7 | 10.3  |
|  Bursitis | 8 | 8 | 5.7 | 6 | 5 | 4.1 | 1.6 | -3.5 | 6.8  |
|  Osteoarthritis, Knee | 10 | 7 | 5.0 | 6 | 6 | 4.9 | 0.1 | -5.1 | 5.4  |
|  Worsening gait/balance | 7 | 7 | 5.0 | 4 | 4 | 3.3 | 1.7 | -3.0 | 6.5  |
|  Other nervous system disorder | 9 | 7 | 5.0 | 11 | 11 | 8.9 | -3.9 | -10.1 | 2.3  |
|  Other disorder of digestive system | 8 | 7 | 5.0 | 10 | 9 | 7.3 | -2.3 | -8.2 | 3.5  |
|  Sensory deficit | 11 | 7 | 5.0 | 3 | 3 | 2.4 | 2.6 | -2.0 | 7.1  |
|  Leg weakness or numbness | 7 | 6 | 4.3 | 12 | 10 | 8.1 | -3.8 | -9.7 | 2.0  |
|  Wound complications dehiscence, bruising-and soft tissue damage | 6 | 6 | 4.3 | 4 | 4 | 3.3 | 1.0 | -3.6 | 5.6  |
|  Dural tear | 6 | 6 | 4.3 | 10 | 10 | 8.1 | -3.8 | -9.7 | 2.0  |
|  Other respiratory disorder; specify | 6 | 6 | 4.3 | 11 | 7 | 5.7 | -1.4 | -6.7 | 3.9  |
|  Other cardiac disorder | 6 | 6 | 4.3 | 11 | 11 | 8.9 | -4.7 | -10.7 | 1.4  |

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|   | Investigational (I) (N=140) |   |   | Controls (C) (N=123) |   |   | I vs C1  |   |   |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Specific Adverse Event | No. of Events | No. of Pts. (n) | % of Pts. (n/N) | No. of Events | No. of Pts. (n) | % of Pts. (n/N) | Diff | LB | UB  |
|  Urinary Tract Infection | 6 | 6 | 4.3 | 3 | 3 | 2.4 | 1.8 | -2.5 | 6.2  |
|  Spinal stenosis lumbar-requiring additional decompression | 4 | 4 | 2.9 | 1 | 1 | 0.8 | 2.0 | -1.1 | 5.2  |
|  Medication Reaction | 4 | 4 | 2.9 | 3 | 3 | 2.4 | 0.4 | -3.5 | 4.3  |
|  Other endocrine or metabolic disorder | 4 | 4 | 2.9 | 2 | 2 | 1.6 | 1.2 | -2.3 | 4.8  |
|  Spinous process fracture affecting device fixation | 4 | 4 | 2.9 | 0 | 0 | 0.0 | 2.9 | 0.1 | 5.6  |
|  Urinary retention | 4 | 4 | 2.9 | 4 | 4 | 3.3 | -0.4 | -4.6 | 3.8  |
|  Other genitourinary disorder | 4 | 4 | 2.9 | 3 | 3 | 2.4 | 0.4 | -3.5 | 4.3  |
|  Motor deficit | 7 | 4 | 2.9 | 13 | 10 | 8.1 | -5.3 | -10.8 | 0.3  |
|  Trauma | 4 | 4 | 2.9 | 3 | 3 | 2.4 | 0.4 | -3.5 | 4.3  |
|  Nerve injury, paralysis or weakness | 3 | 3 | 2.1 | 2 | 2 | 1.6 | 0.5 | -2.8 | 3.8  |
|  Spinous process fracture, specify displaced or non-displaced | 3 | 3 | 2.1 | 0 | 0 | 0.0 | 2.1 | -0.3 | 4.5  |
|  Headache | 3 | 3 | 2.1 | 3 | 3 | 2.4 | -0.3 | -3.9 | 3.3  |
|  Other disorders of fluid, electrolyte or acid-base balance | 3 | 3 | 2.1 | 0 | 0 | 0.0 | 2.1 | -0.3 | 4.5  |
|  Other disorder of skin/subcutaneous tissue | 5 | 3 | 2.1 | 5 | 5 | 4.1 | -1.9 | -6.2 | 2.3  |
|  Other renal disorder | 3 | 3 | 2.1 | 1 | 1 | 0.8 | 1.3 | -1.5 | 4.2  |
|  Mood affective-disorders (e.g. depression) | 3 | 3 | 2.1 | 3 | 3 | 2.4 | -0.3 | -3.9 | 3.3  |
|  Cancer | 3 | 3 | 2.1 | 1 | 1 | 0.8 | 1.3 | -1.5 | 4.2  |
|  Mechanical failure of device (breakage, separation, disassembly) | 2 | 2 | 1.4 | 0 | 0 | 0.0 | 1.4 | -0.5 | 3.4  |
|  Osteoarthritis, other | 2 | 2 | 1.4 | 2 | 2 | 1.6 | -0.2 | -3.2 | 2.8  |
|  Disc herniation System | 2 | 2 | 1.4 | 2 | 2 | 1.6 | -0.2 | -3.2 | 2.8  |
|  Other lymphovascular disorder | 2 | 2 | 1.4 | 3 | 3 | 2.4 | -1.0 | -4.4 | 2.4  |
|  Disorders of ear | 2 | 2 | 1.4 | 3 | 3 | 2.4 | -1.0 | -4.4 | 2.4  |
|  Disorders of nose | 2 | 2 | 1.4 | 3 | 3 | 2.4 | -1.0 | -4.4 | 2.4  |
|  Disorders of throat | 2 | 2 | 1.4 | 1 | 1 | 0.8 | 0.6 | -1.9 | 3.1  |
|  Disorder of esophagus, stomach or duodenum | 2 | 2 | 1.4 | 1 | 1 | 0.8 | 0.6 | -1.9 | 3.1  |
|  Notes:1 95% binomial confidence interval without PS adjustment.  |   |   |   |   |   |   |   |   |   |

PMA P220031: FDA Summary of Safety and Effectiveness Data

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Table 12: All Adverse Events (ITT-PS Selected analysis set) - continued

|   | Investigational (I) (N=140) |   |   | Controls (C) (N=123) |   |   | I vs C1  |   |   |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Specific Adverse Event | No. of Events | No. of Pts. (n) | % of Pts. (n/N) | No. of Events | No. of Pts. (n) | % of Pts. (n/N) | Diff | LB | UB  |
|  Disorder of intestines; specify | 2 | 2 | 1.4 | 1 | 1 | 0.8 | 0.6 | -1.9 | 3.1  |
|  Device; other, specify | 2 | 2 | 1.4 | 0 | 0 | 0.0 | 1.4 | -0.5 | 3.4  |
|  Sprain; specify site | 2 | 2 | 1.4 | 0 | 0 | 0.0 | 1.4 | -0.5 | 3.4  |
|  Rash vascular | 2 | 2 | 1.4 | 2 | 2 | 1.6 | -0.2 | -3.2 | 2.8  |
|  Hematuria | 2 | 2 | 1.4 | 1 | 1 | 0.8 | 0.6 | -1.9 | 3.1  |
|  Other mental or behavioral disorder; specify | 3 | 2 | 1.4 | 4 | 4 | 3.3 | -1.8 | -5.5 | 1.9  |
|  Reflex deficit, specify | 3 | 2 | 1.4 | 0 | 0 | 0.0 | 1.4 | -0.5 | 3.4  |
|  Lower extremity swelling | 2 | 2 | 1.4 | 2 | 2 | 1.6 | -0.2 | -3.2 | 2.8  |
|  Thoracic Stenosis | 2 | 2 | 1.4 | 0 | 0 | 0.0 | 1.4 | -0.5 | 3.4  |
|  Cervical Stenosis | 2 | 2 | 1.4 | 0 | 0 | 0.0 | 1.4 | -0.5 | 3.4  |
|  Pneumonia | 1 | 1 | 0.7 | 4 | 4 | 3.3 | -2.5 | -6.0 | 0.9  |
|  Pulmonary Embolism | 1 | 1 | 0.7 | 3 | 3 | 2.4 | -1.7 | -4.8 | 1.3  |
|  Hypertension | 1 | 1 | 0.7 | 1 | 1 | 0.8 | -0.1 | -2.2 | 2.0  |
|  Cardiogenic shock | 1 | 1 | 0.7 | 0 | 0 | 0.0 | 0.7 | -0.7 | 2.1  |
|  Dysesthesia | 1 | 1 | 0.7 | 0 | 0 | 0.0 | 0.7 | -0.7 | 2.1  |
|  Loss of bowel/bladder function | 1 | 1 | 0.7 | 1 | 1 | 0.8 | -0.1 | -2.2 | 2.0  |
|  CSF leak | 1 | 1 | 0.7 | 2 | 2 | 1.6 | -0.9 | -3.5 | 1.7  |
|  Sexual dysfunction | 1 | 1 | 0.7 | 0 | 0 | 0.0 | 0.7 | -0.7 | 2.1  |
|  Deep Vein Thrombosis | 1 | 1 | 0.7 | 2 | 2 | 1.6 | -0.9 | -3.5 | 1.7  |
|  Bone erosion | 1 | 1 | 0.7 | 0 | 0 | 0.0 | 0.7 | -0.7 | 2.1  |
|  Fever | 1 | 1 | 0.7 | 1 | 1 | 0.8 | -0.1 | -2.2 | 2.0  |
|  Septicemia | 1 | 1 | 0.7 | 1 | 1 | 0.8 | 0 | -2.2 | 2.0  |
|  Ileus or intestinal obstruction | 1 | 1 | 0.7 | 2 | 2 | 1.6 | -0.9 | -3.5 | 1.7  |
|  Allergic Reaction | 1 | 1 | 0.7 | 3 | 3 | 2.4 | -1.7 | -4.8 | 1.3  |
|  Dyspnea | 1 | 1 | 0.7 | 3 | 3 | 2.4 | -1.7 | -4.8 | 1.3  |
|  Bleeding | 1 | 1 | 0.7 | 1 | 1 | 0.8 | -0.1 | -2.2 | 2.0  |
|  Hematoma | 1 | 1 | 0.7 | 3 | 1 | 0.8 | -0.1 | -2.2 | 2.0  |
|  Other access site complications; specify includes pain | 1 | 1 | 0.7 | 1 | 1 | 0.8 | -0.1 | -2.2 | 2.0  |
|  Diabetes mellitus | 1 | 1 | 0.7 | 2 | 2 | 1.6 | -0.9 | -3.5 | 1.7  |
|  Thyroid disorder; specify includes hypo- and hyperthyroidism | 1 | 1 | 0.7 | 4 | 4 | 3.3 | -2.5 | -6.0 | 0.9  |
|  Disorders of other endocrine glands | 1 | 1 | 0.7 | 0 | 0 | 0.0 | 0.7 | -0.7 | 2.1  |
|  Visual disturbances; specify includes glaucoma, cataract | 1 | 1 | 0.7 | 0 | 0 | 0.0 | 0.7 | -0.7 | 2.1  |

PMA P220031: FDA Summary of Safety and Effectiveness Data

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|   | Investigational (I) (N=140) |   |   | Controls (C) (N=123) |   |   | I vs C¹  |   |   |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Specific Adverse Event | No. of Events | No. of Pts. (n) | % of Pts. (n/N) | No. of Events | No. of Pts. (n) | % of Pts. (n/N) | Diff | LB | UB  |
|  Other disorder of eye; specify includes corneal irritation, pain | 2 | 1 | 0.7 | 2 | 2 | 1.6 | -0.9 | -3.5 | 1.7  |
|  Compression fracture; specify site | 1 | 1 | 0.7 | 1 | 1 | 0.8 | -0.1 | -2.2 | 2.0  |
|  Coccydynia | 1 | 1 | 0.7 | 0 | 0 | 0.0 | 0.7 | -0.7 | 2.1  |
|  Infection other than surgical wound infection, includes pain | 1 | 1 | 0.7 | 2 | 2 | 1.6 | -0.9 | -3.5 | 1.7  |
|  Renal failure | 1 | 1 | 0.7 | 0 | 0 | 0.0 | 0.7 | -0.7 | 2.1  |
|  Anxiety disorders | 1 | 1 | 0.7 | 0 | 0 | 0.0 | 0.7 | -0.7 | 2.1  |
|  Adjacent Segment Disease | 1 | 1 | 0.7 | 10 | 10 | 8.1 | -7.4 | -12.4 | -2.4  |
|  Hypotension | 0 | 0 | 0.0 | 1 | 1 | 0.8 | -0.8 | -2.4 | 0.8  |
|  Arrhythmia | 0 | 0 | 0.0 | 5 | 5 | 4.1 | -4.1 | -7.6 | -0.6  |
|  Congestive Heart Failure | 0 | 0 | 0.0 | 1 | 1 | 0.8 | -0.8 | -2.4 | 0.8  |
|  Implant material reaction | 0 | 0 | 0.0 | 2 | 2 | 1.6 | -1.6 | -3.9 | 0.6  |
|  Anemia | 0 | 0 | 0.0 | 9 | 8 | 6.5 | -6.5 | -10.9 | -2.1  |
|  Angina | 0 | 0 | 0.0 | 2 | 2 | 1.6 | -…

---

**Source:** [https://fda.innolitics.com/device/P220031](https://fda.innolitics.com/device/P220031)

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