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U.S. Department of Health and Human Services

Post-Approval Studies (PAS) Database

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The FDA has the authority to require sponsors to perform a post-approval study (or studies) at the time of approval of a premarket approval (PMA), humanitarian device exemption (HDE), or product development protocol (PDP) application. Post-approval studies can provide patients, health care professionals, the device industry, the FDA and other stakeholders information on the continued safety and effectiveness (or continued probable benefit, in the case of an HDE) of approved medical devices. This database allows you to search Post-Approval Study information by applicant or device information.

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Patient Specific Talus Spacer PAS

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Study Status Progress Adequate
Application Number /
Requirement Number
H200001 / PAS001
Date Original Protocol Accepted 02/17/2021
Date Current Protocol Accepted 01/14/2022
Study Name Patient Specific Talus Spacer PAS
Device Name Patient Specific Talus Spacer
General Study Protocol Parameters
Study Design Prospective Cohort Study
Data Source New Data Collection
Comparison Group Objective Performance Criterion
Analysis Type Analytical
Study Population Adult: >21
Detailed Study Protocol Parameters
Study Objectives The study objective is to evaluate the continued safety and probable benefit of the Talus Spacer in commercial use. The Patient Specific Talus Spacer PAS is a prospective, single-arm, multicenter US observational study to provide ongoing safety and probable benefit assessment of the Patient Specific Talus Spacer in treatment of avascular necrosis of the ankle.
Study Population 50 adult subjects who have been diagnosed with avascular necrosis (AVN) in the ankle joint
Sample Size A minimum number of 50 patients will be enrolled in this study. Of the 50 subjects, a minimum of 20 subjects will receive a Cobalt Chromium Patient Specific Talus Spacer and a minimum of 20 subjects will receive a Titanium (Ti6Al4V) with Titanium Nitride (TiN) coating Patient Specific Talus Spacer. The total sample size is based on both the safety and probable benefit hypotheses, accounts for 10% lost-to-follow-up, and ensures 90% statistical power using an unadjusted chi-square test with a 1-sided type 1 error rate of a = 0.05. The failure rate with device removal or serious device-related adverse event by Year 5 of the patient specific talus spacer is assumed to be lower than the failure rate with a non-union of the comparator, tibiotalocalcaneal fusion with allograft. For patients without failure, a >=20-point improvement on a 100-point scale for the Visual Analog Scale (VAS) pain scale at 5 years compared to baseline is assumed. The sample size for each material group is determined to ensure statistical power for the subgroup analysis.
Key Study Endpoints Primary Probable Benefit Endpoint:
The primary probable benefit endpoint is a clinically significant improvement in pain, as demonstrated by a = 20-point improvement on a 100-point scale for the Visual Analog Scale (VAS) pain scale at 5 years compared to baseline. Patients who undergo an SSSI will be defined as probable benefit endpoint failures. Therefore, a patient will achieve the primary probable benefit endpoint only if they do not undergo an SSSI and they achieve a = 20-point improvement in VAS pain.

Primary Safety Endpoint:
Based on the need for a subsequent secondary surgical intervention (SSSI) or Device Related Serious Adverse Events (“SAEs”) at 5 years post-procedure.

The following secondary safety endpoints will also be assessed:
• Adverse events (“AEs”)
• Device - or procedure related AEs
• Serious AEs (“SAEs”)

Additional Analyses:
Improvement at 5 years post-procedure compared to Pre-op on:
• Ankle ROM;
• FAOS for:
a. Pain
b. Symptom
c. Sport/Rec
d. Activities of Daily Living (“ADL”); and
e. Quality of Life (“QoL”)

Other Exploratory Analyses:
• X-ray Assessment and Measurements:
a. Tibiotalar Alignment
b. Talar Tilt Angle
c. Boehler’s Angle
d. Talar declination angle
e. Meary’s angle
Follow-up Visits and Length of Follow-up 5 years
Interim or Final Data Summary
Interim Results No results yet available
Actual Number of Patients Enrolled 3
Actual Number of Sites Enrolled 6
Patient Follow-up Rate Data not available - First three patients just implanted

Patient Specific Talus Spacer PAS Reporting Schedule

Reporting Schedule
Date Due
FDA Receipt
Applicant's Reporting Status
6 month report 08/18/2021 08/16/2021 On Time
1 year report 02/17/2022 02/16/2022 On Time
18 month report 08/18/2022 08/17/2022 On Time
2 year report 02/17/2023    
3 year report 02/17/2024    
4 year report 02/16/2025    

Contact Us

Mandated Studies Program
Food and Drug Administration
10903 New Hampshire Ave.
Silver Spring, MD 20993-0002
Email: MandatedStudiesPrograms@fda.hhs.gov

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