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The AeroForm® Tissue Expander System, Smooth is used for soft tissue expansion in breast reconstruction following mastectomy, for the treatment of underdeveloped breasts and for the treatment of soft tissue deformities in the breast.

The AeroForm® Tissue Expander, Smooth is intended for temporary subcutaneous or submuscular implantation and is not intended for use beyond six months

The AeroForm Tissue Expander System, Smooth is a sterile, temporary implant for breast reconstruction. This device is comprised of an implantable tissue expander (Expander), a remote control (Controller), and a Master Key. The AeroForm Tissue Expander, Smooth is constructed of an outer silicone shell and an inner gas barrier (bag) with an internal reservoir of compressed Carbon Dioxide (CO2) gas. The CO2 gas is released within the Expander by using the remote control (Controller), resulting in gradual expansion of the Expander. In a typical, two-stage breast reconstruction, a tissue expander device is placed under the pectoralis major muscle and remaining skin following a mastectomy procedure. The Expander is gradually expanded over time through the release of carbon dioxide, causing the overlying skin and muscle to stretch. When adequate tissue coverage is achieved, the expansion device is removed and replaced with a breast implant.

This document describes the premarket notification for the AeroForm Tissue Expander System, Smooth. The "acceptance criteria" and "device performance" in this context refer to the mechanical and performance testing conducted to demonstrate substantial equivalence to a predicate device, rather than the performance of an AI/ML model.

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Acceptance Criteria and Reported Device Performance

The acceptance criteria for this device are based on demonstrating that the modified device (smooth shell) meets the design input requirements and performs equivalently to the predicate device (textured shell). The study focuses on mechanical performance testing as outlined in ASTM F1441 and internal design verification and validation testing.

Table of Acceptance Criteria and Reported Device Performance:

Since this submission is for a medical device (tissue expander) and not an AI/ML product, the following points regarding AI/ML study design are not applicable to this document. The information provided does not describe an AI/ML study.

2. Sample size used for the test set and the data provenance: Not applicable; no AI/ML test set is described.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts: Not applicable; ground truth establishment for an AI/ML model is not described.
4. Adjudication method (e.g., 2+1, 3+1, none) for the test set: Not applicable; no expert adjudication for an AI/ML test set.
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: Not applicable; no AI assistance for human readers is described.
6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done: Not applicable; this device is not an algorithm.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.): Not applicable; no ground truth for an AI/ML model. The "ground truth" for this device's performance is derived from standardized mechanical testing and design verification.
8. The sample size for the training set: Not applicable; no AI/ML training set is described.
9. How the ground truth for the training set was established: Not applicable; no AI/ML training set is described.

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The AeroForm® Tissue Expander System is used for soft tissue expansion in breast reconstruction following mastectorny. for the treatment of underdeveloped breasts, and for the treatment of soft tissue deformities in the breast.

The AeroForm® Tissue Expander is intended for temporary subcutaneous or submuscular implantation and is not intended for use beyond 6 months.

The AeroForm Tissue Expander System (AeroForm System) is a sterile temporary implant for breast reconstruction and is comprised of a sterile, implantable tissue expander), a remote control (Controller), and a Master Key. The AeroForm Tissue Expander is a comprised of an outer textured silicone shell, an inner gas barrier (bag), with an internal reservoir of compressed Carbon Dioxide (CO2) gas, which is released within the Expander by using the remote control (Controller), resulting in gradual expansion of the Expander. In a typical, twostage breast reconstruction, a tissue expander device is placed under the pectoralis major muscle and remaining skin following a mastectomy procedure. The Expander is gradually expanded over time through the release of carbon dioxide, causing the overlying skin and muscle to stretch. When adequate tissue coverage is achieved, the expansion device is removed and replaced with a breast implant.

This document describes the regulatory submission for the AeroForm Tissue Expander System. It is not an AI/ML device, so many of the requested fields are not applicable. I will fill in the applicable information about the device's acceptance criteria and the studies performed.

1. A table of acceptance criteria and the reported device performance

2. Sample sized used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

The document primarily describes pre-clinical and verification/validation testing for a physical medical device (tissue expander). There is no mention of a "test set" in the context of an AI/ML device employing a dataset for evaluation. The "test set" for mechanical and biological performance refers to the physical devices and materials tested. The provenance of these tests are standard laboratory and engineering tests; no data provenance from patient populations is mentioned for these specific tests in the provided text.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)

Not applicable. This is not an AI/ML device relying on expert-annotated ground truth for a test set. The "ground truth" for the performance attributes is established through recognized international standards (e.g., ASTM F1441, EN ISO 10993) and internal engineering specifications, executed and assessed by qualified engineering and scientific personnel.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set

Not applicable. As this is not an AI/ML device, there is no expert adjudication of outputs from an algorithm. Results are assessed against pre-defined quantitative and qualitative acceptance criteria from recognized standards and internal specifications.

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

Not applicable. This is not an AI/ML device, and no MRMC study with human readers or AI assistance was conducted or mentioned.

6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done

Not applicable. This is a physical medical device (tissue expander) with a software component for control; it is not a standalone algorithm. The software testing mentioned is for the functionality and compliance of the embedded software, not for a diagnostic or predictive AI algorithm.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc)

The "ground truth" for this device's performance evaluation lies in:

• Mechanical Integrity/Performance: Compliance with ASTM F1441 standards and internal engineering design specifications.
• Biocompatibility: Conformance to EN ISO 10993 standards.
• Software: Compliance with EN 62304 and FDA guidance for software development (functional correctness, safety).
• Sterilization/Shelf Life: Compliance with applicable standards for sterility, package integrity, and stability over time.

These are established through standardized testing methodologies rather than expert consensus on medical images or pathology.

8. The sample size for the training set

Not applicable. This is not an AI/ML device that requires a training set.

9. How the ground truth for the training set was established

Not applicable. This is not an AI/ML device that requires a training set.

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The AeroForm Tissue Expander System is used for soft tissue expansion in breast reconstruction following mastectomy, for the treatment of underdeveloped breasts, and for the treatment of soft tissue deformities in the breast.

The AeroForm Expander is intended for temporary subcutaneous or submuscular implantation and is not intended for use beyond six months.

The AeroForm® Tissue Expander System is comprised of the AeroForm Tissue Expander, the Dosage Controller, and the Physician Master Key. The AeroForm Tissue Expander is a sterile implant with an outer textured silicone shell and a non-distensible inner bag which are anatomically shaped to allow for directional expansion in the lower, anterior pole. The AeroForm Tissue Expander contains a reservoir of compressed carbon dioxide (CO2), which is released within the AeroForm Tissue Expander by using the Dosage Controller. The outer shell has suture tabs to allow fixation of the device to the surrounding tissues to prevent rotation. A receiving antenna and electronics within the AeroForm Tissue Expander enable communication with the Dosage Controller. The AeroForm Tissue Expander has no intrinsic electrical power, batteries, or software, and can only be activated by the Dosage Controller. There are 3 different sizes of the expander, including small (400cc), medium (600cc), and large (850cc). The Dosage Controller is a small, hand held battery-powered, non-sterile device. It activates the AeroForm Tissue Expander to release the programmed amount of CO2 gas (10cc). The Dosage Controller is configured to provide coded instructions to its bonded AeroForm Tissue Expander. It has a single push button for ease of use and a bank of indicator lights (LEDs) and tones. The Physician Master Key is used only by the physician in the operating room or in the physician office. With the Physician Master Kev inserted into the Dosage Controller receptacle, the Dosage Controller can activate the Expander with no daily limit on the expansion volume.

The AeroForm® Tissue Expander System underwent extensive testing, encompassing biocompatibility, shelf-life, electromagnetic compatibility, software verification, and performance bench testing. A pivotal clinical study, XPAND trial (CPT-0003), and a Continued Access Study (CAS) provided critical insights into its performance and safety in a real-world setting.

1. Acceptance Criteria and Reported Device Performance

The acceptance criteria for several non-clinical tests and the corresponding reported device performance are summarized below:

2. Sample Size and Data Provenance

Pivotal Study (XPAND Trial - CPT-0003):

• Sample Size (Test Set - Effectiveness Analysis): 151 patients (99 AeroForm patients and 52 saline patients for effectiveness analysis). The analysis was per breast: 155 AeroForm breasts and 83 Saline breasts.
• Sample Size (Test Set - Safety Analysis): 158 subjects enrolled (106 randomized to AeroForm, 52 to Saline). One AeroForm subject was randomized but no device implanted, so 157 subjects for safety analysis.
• Data Provenance: Prospective, multi-center, randomized, controlled, open-label study conducted at 17 investigational sites in the U.S.

Continued Access Study (XPAND II CAS):

• Sample Size (Test Set): 28 subjects (49 breasts) enrolled as of June 8, 2016. Data available for 11 subjects (21 breasts) who completed the final study visit.
• Data Provenance: Prospective, multi-center, single-arm study of the V2.5 device.

Prior Investigations (Australia):

• Sample Size: 40 subjects (71 AeroForm Tissue Expanders) in the PACE 1 and PACE 2 studies. 21 subjects (34 AeroForm Expanders) in a second Australian study.
• Data Provenance: Two-phase single-center, prospective, open-label clinical study (PACE) in Perth, Australia. Second study also conducted in Australia. These were prior investigations, likely used for early feasibility and design refinement.

3. Number of Experts and Qualifications for Ground Truth

The document does not explicitly state the number of experts or their specific qualifications (e.g., radiologist with 10 years of experience) used to establish ground truth for image-based assessments. However, the ground truth for the clinical study was based on:

• Treatment Success: Defined by successful tissue expansion and exchange to a permanent breast implant, unless precluded by a non-device-related event. This assessment would have been made by the investigating physician (surgeon) at each site.
• Adverse Events: Clinical observations and diagnoses made by the investigator (physician).
• Patient-reported outcomes: Patient satisfaction and pain ratings, which are self-reported.
• Physician satisfaction: Reported by the investigating physicians.

These are clinical outcomes determined by the treating physicians and patient self-assessment, rather than independent expert consensus on specific objective findings like image interpretation.

4. Adjudication Method for the Test Set

The document does not specify a formal adjudication method (e.g., 2+1, 3+1) for the clinical outcomes in the pivotal study or the CAS. The clinical outcomes (treatment success, adverse events) were reported by the investigators at each site. Given the nature of breast reconstruction outcomes, these are typically determined by the operating surgeon and clinical staff based on direct patient assessment and surgical findings, rather than independent adjudication of ambiguous findings.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No Multi-Reader Multi-Case (MRMC) comparative effectiveness study was mentioned. The pivotal study was a direct comparison between the AeroForm Tissue Expander System and standard saline tissue expanders, both used by human clinicians. The comparison was of device performance and patient outcomes, not of human reader improvement with or without AI assistance, as the device itself is not an AI diagnostic tool.

6. Standalone (Algorithm Only) Performance

The AeroForm Tissue Expander System is a physical medical device (implant, controller, master key), not a diagnostic algorithm or AI system. Therefore, a standalone (algorithm-only) performance study is not applicable and was not conducted. The software component manages the device's function (e.g., CO2 dosing, communication) and its validation focused on software reliability, safety, and hazard analysis, as outlined in the "SOFTWARE" section.

7. Type of Ground Truth Used

• Clinical Studies (XPAND Trial & CAS): The ground truth for effectiveness was primarily based on clinical outcomes data, specifically whether tissue expansion was successful and led to exchange with a permanent breast implant. Safety ground truth was established through recorded adverse events and device malfunctions observed during the clinical course. Patient and physician satisfaction ratings were also used.
• Non-Clinical (Bench, Biocompatibility, EMC) Studies: Ground truth for these studies was established by pre-defined quantitative and qualitative acceptance criteria for specific physical, chemical, and electrical properties, as measured by standardized testing methodologies.

8. Sample Size for the Training Set

The document does not mention a separate "training set" in the context of machine learning or AI models, as the AeroForm Tissue Expander System is a physical device, not an AI/ML product.

However, if "training set" is meant to refer to early clinical data used to refine the device or inform the pivotal study design:

• PACE Studies (Australia): 40 subjects (71 AeroForm Expanders V1.0 and V2.0).
• Second Australian Study: 21 subjects (34 AeroForm Expanders).
• Sheep Implant Study: 2 male ovine subjects, 12 implants. This was a preliminary safety evaluation.

These earlier studies and animal trials served as an evolutionary process, leading to modifications (V2.0 to V2.5) that reduced malfunctions, similar to how a training set might inform model refinements.

9. How the Ground Truth for the Training Set was Established

As clarified in point 8, there isn't a "training set" in the AI sense for this physical device. However, the "ground truth" for the early studies (PACE, second Australian study, sheep study) that informed device development and modification was established through:

• Clinical Observation: Direct assessment by surgeons/investigators of device function, tissue expansion, patient comfort, and any adverse events or complications.
• Surgical Outcomes: Success of expansion, ability to proceed to permanent implant exchange, and any device-related failures requiring intervention.
• Animal Study Observations: Monitoring of animal subjects for pain, discomfort, and general health, along with assessment of device function in vivo.
• Device Performance Monitoring: Tracking of CO2 release, communication, and instances of under/over expansion or deflation.

These observations and outcomes from early non-clinical and clinical experience directly led to the design modifications (e.g., V2.5 with enhanced inner liner and software reprogramming) aimed at improving device performance and reducing malfunctions observed in the V2.0 version.

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