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The Magna-ROM 21 Knee System is intended for replacement of the knee joint during total knee arthroplasty. Components of the Magna-ROM system are intended for use only with bone cement. Specific diagnostic indications include:

1. Patient conditions of inflammatory degenerative joint disease (e.g., rheumatoid arthritis).
2. Patient conditions of noninflammatory degenerative joint disease (e.g., osteoarthritis, avascular necrosis).
3. Correctable valgus-varus deformity and moderate flexion contracture.
4. Those patients with failed previous surgery where pain, deformity or dysfunction persists.
5. Revision of previously failed knee arthroplasty.

The Magna-ROM 21 Knee System is a total primary knee system that was designed to provide a better proportional fit for people of Asian descent. Studies of Japanese and Chinese anatomy have shown that the shape of the knee is slightly different than the European or American knee, particularly in the smaller adult. Results of a study in which Sulzer Orthopedics examined CT-scan data from 52 Japanese patients showed that the anterior/posterior depth is smaller for the Asian knee as compared to the American or European knee, and the medial/lateral width is larger.

Components of the Magna-ROM 21 Knee System are basically the same as conventional knee components. However, based on the data collected from the CT-Scan study, dimensions of the Magna-ROM components were scaled to address those patients who exhibit the need (through preoperative templating) for somewhat wider mediolateral coverage and smaller anteroposterior coverage than conventional knee components can provide. The size range for the Magna-ROM system also includes proportionally smaller components than conventional knee components because of the smaller adult sizes in the Asian population.

The design features for each Magna-ROM component are described below.

Femoral Component: The femoral component is a total condylar prosthesis that is manufactured from cast CoCr alloy. It has an anatomical design and will be offered in five sizes in both left and right configurations. The interior box of the femoral component is porous coated with Sulzer Orthopedics™ Cancellous Structured Titanium™ (CSTi™) for potentially enhanced cement fixation. The femoral component incorporates a deep patellar groove that conforms to the geometry of the patella prosthesis and provides for rolling/sliding articulation. The condylar geometry is rounded in both the anterior/posterior and medial/lateral planes to enhance contact area with the polyethylene tibial insert. The posterior condyles are slightly longer than conventional femoral components to facilitate optimum range of motion.

Tibial Component: The tibial component consists of a metal baseplate that is manufactured from cast Ti-6Al-4V alloy that is used in conjunction with a snap-in polyethylene insert. The tibia component is a symmetric design, eliminating the need for left and right configurations. The tibia baseplate will be offered in five sizes and has a wing-shaped keel for enhanced fixation within the intramedullary canal. Rotational stability is provided by two posterior fixation pegs. The underside of the baseplate, with the exception of the keel, is porous coated with CSTi for potentially enhanced cement fixation. Two screwholes are provided for the possible use of bone screws, if desired by the surgeon. Tibial inserts will be offered in four thicknesses (6mm to 13mm) for each size and are designed with a snap-lock mechanism for attachment to the baseplate. The insert comes in two styles, both of which are designed to preserve the posterior cruciate ligament PCL. The cruciate supplementing design is for those patients with a weaker PCL and/or soft tissue laxity. Resistance to anterior and posterior subluxation is supplied by a moderately constraining surface geometry. This design yields up to 120° of flexion, as determined by CAD kinematic overlay analysis. The cruciate sparing design will be used for those patients with good ligament support. This style has slightly larger posterior radii. This, along with the longer posterior condyles of the femoral component, facilitates a larger range of motion (up to 135° of flexion).

Patella: The patella prosthesis is a cemented all-polyethylene component and comes in two styles: a round patella, which is recessed in the bone, and an offset patella, which utilizes a surface technique. The offset patella is slightly elliptical in shape and the crest is medial of center to more closely replicate the natural anatomy. Three sizes of each style will be available and may be matched with any size femoral component.

The provided text describes a 510(k) premarket notification for the Sulzer Orthopedics® Magna-ROM™ 21 Knee System, a total primary knee system. The submission focuses on demonstrating substantial equivalence to previously marketed devices rather than presenting a study to prove that the device meets specific acceptance criteria based on a clinical trial or performance study with defined endpoints.

Here's an analysis of the requested information based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance:

The document does not explicitly define "acceptance criteria" in the form of quantitative performance targets for the Magna-ROM 21 Knee System. Instead, it relies on demonstrating substantial equivalence to existing predicate devices (Sulzer Orthopedics Natural-Knee II System and Apollo Knee System). The "reported device performance" is described in terms of its similarity to these predicates and specific mechanical testing results, rather than clinical performance metrics for the knee system itself.

2. Sample Size Used for the Test Set and Data Provenance:

The document describes several distinct "studies" or analyses, but none of them are presented as a single "test set" for validating the entire device's clinical performance.

• CT-Scan Data for Anatomical Design: Data from 52 Japanese patients was used to inform the design of the Magna-ROM components to accommodate Asian anatomy. The provenance is Japanese CT-scan data, and it is implied to be retrospective as it was used to design the device, not to test its performance post-design.
• Biomechanical Testing (Constraint, Fatigue, Attachment Strength): The sample sizes for these in-vitro laboratory tests are not provided in the summary. They are comparative tests against a "commercially available device" or "Greenwald et al." standards. The provenance is implied to be from laboratory testing, likely prospective for the specific components being tested.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts:

This information is not provided in the document. The "ground truth" for the biomechanical tests would be the established standards or predicate device performance, not expert consensus in the clinical sense. For the anatomical design study, the CT-scan data serves as the "ground truth" for anatomical measurements, interpreted by the engineers/researchers at Sulzer, but specific expert involvement in defining this "truth" isn't detailed.

4. Adjudication Method for the Test Set:

This information is not applicable as there is no clinical "test set" requiring adjudication by experts. The biomechanical tests would have their own defined protocols and success/failure criteria.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, If So, What Was the Effect Size of How Much Human Readers Improve with AI vs Without AI Assistance:

This information is not applicable. The Magna-ROM 21 Knee System is a surgical implant (a knee prosthesis), not an AI-powered diagnostic device. Therefore, MRMC studies and AI assistance are irrelevant to its evaluation as described in this 510(k) summary.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done:

This information is not applicable. The device is a physical knee implant, not an algorithm.

7. The Type of Ground Truth Used:

• For the anatomical design study, the ground truth was CT-scan data of patient anatomy.
• For the biomechanical testing (tibiofemoral/patellofemoral constraint, tibial baseplate fatigue, insert attachment strength), the ground truth was established biomechanical standards (e.g., Greenwald et al.) and the performance of commercially available predicate devices.
• For range of motion, the ground truth was determined by CAD kinematic overlay analysis.

8. The Sample Size for the Training Set:

The document doesn't explicitly describe a "training set" in the context of a machine learning model. However, if we interpret "training set" as the data used to inform the design of the product:

• The anatomical design was informed by CT-scan data from 52 Japanese patients. This could be considered akin to a "training set" for the design specifications.
• There's no mention of a separate training set for biomechanical properties; these are likely designed to meet established engineering standards from the outset.

9. How the Ground Truth for the Training Set Was Established:

For the anatomical design information, the ground truth was established through CT-scan imaging of 52 Japanese patients. This objective medical imaging data provided the detailed anatomical measurements (anterior/posterior depth, medial/lateral width) that informed the scaling and design of the Magna-ROM components. This data was then presumably analyzed by engineers and designers at Sulzer Orthopedics to derive the design specifications.

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