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U.S. Department of Health and Human Services

Post-Approval Studies (PAS)

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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) approved medical devices. This database allows you to search Post-Approval Study information by applicant or device information.

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OSB Lead-Long Term Study


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General
Application Number P050050 / PAS001
Current Plan Approved 05/09/2014
Study Name OSB Lead-Long Term Study
General Study Protocol Parameters
Study Design Prospective Cohort Study
Data Source New Data Collection
Comparison Group Historical Control
Analysis Type Analytical
Study Population Adult: >21
Detailed Study Protocol Parameters
Study Design Description The specific objective of this long-term study is to obtain information on the revision and removal rate for the STAR Ankle over time in order to establish the device¿s survivorship.

The post approval study is a prospective, multi-center, single-arm study at up to the 10 primary sites that participated in the pivotal and continued access studies. The study is continued follow-up of the premarket cohort and continued access cohort.The long-term results of Ankle Arthrodesis summarized from literature review by meta-analysis will be used as historical fusion control.

Study Population Description The study population consists of all living subjects who participated in the continued access study.

Device Group: subjects implanted with the STAR Ankle

Comparison Group: Historical Fusion Control (i.e., the long-term results of Ankle Arthrodesis summarized from literature review by meta-analysis) Fusion results reported by Haddad, et al. (2007)7 will serve as the control group for the STAR Continued Access subjects. [Haddad SL, Coetzee JC, Estok R, Fahrbach K, Banel D, Nalysnyk L. Intermediate and long-term outcomes of total ankle arthroplasty and ankle arthrodesis. A systematic review of the literature. J Bone Joint Surg Am. 2007 Sep;89(9):1899-905.]

Sample Size minimum 125 patients (STAR Ankle recipients)



The comparison of the STAR ankle is to a literature control, in Haddad et al. [2007], with a survivorship rate of 86.3%. An informal calculation indicates how many successes are needed in the STAR ankle group to claim non-inferiority. Sponsor assumed that the observed success rate for the fusion control was 94/109 = 86.3%, where the 109 is the effective sample size. Then, from StatXact-8 software, 40/47 = 85.1% is the smallest observed success rate so that a lower 90% confidence bound for the difference of success probabilities is no less than ¿15%. Note: This calculation uses two observed proportions, and is not a power-based calculation of detectable effect size.

Using PASS2005 sample size software, the sponsor performed a two-sample, exact non-inferiority calculation to compare the STAR ankle to a historical control with 109 subjects, a true success rate of 86.3%, and using a one-sided test with 5% Type 1 error rate, 80% power, and a 15% non-inferiority margin. The necessary sample size to show non-inferiority is 47 subjects in the STAR ankle study arm. However, SBi¿s intention is to enroll at minimum 125 patients and follow all who continue to participate. The meta-analysis performed by Haddad et al. [2007] had a sample size of 1262 subjects who received an arthrodesis. However, for purposes of the sample size calculation, the effective sample size in Haddad et al. [2007] is only 109, far less than the 1262 subjects in the articles that were included in Haddad¿s meta-analysis. A technical justification for this reduced number of control subjects appears in protocol Section 6.1.3.1
Data Collection Primary Effectiveness Endpoint

Device Survivorship (Revision and Removal) at 8 years after implantation

Note: The information collected at these post-operative intervals will be added to the previously collected follow-up data (e.g., demographic, baseline, post-operative through 24-months).



Other Effectiveness Endpoints

Total Buechel-Pappas Scale score

(100-point scale consisting of subscales for pain (40 points), function (40 points), range of motion (15 points), and deformity (5 points))

Pain Visual Analog Scale (VAS) (100mm scale)

Quality of Life (SF-36)

AOFAS

Radiographic endpoints (assessed by Anterior-posterior and lateral x-ray images of the treated ankle)

Radiolucency

Migration

Safety Endpoints

All adverse events, including information concerning the nature, onset, duration, severity, and relationship to the device and operative procedure

Follow-up Visits and Length of Follow-up 96 months

48 months (± 8 weeks) , 72 months (± 8 weeks), and 96 months

(-8 weeks and any time after 96 Months) post-operatively. Baseline, 6 week, 12 month, and 24 month data will be used as collected for the study in which they originally participated.



OSB Lead-Long Term Study Schedule

Report Schedule
Report
Date Due
FDA Receipt
Date
Applicant's Reporting Status
6 month report 11/25/2009 02/17/2010 Overdue/Received
1 year report 05/27/2010 05/28/2010 Overdue/Received
18 month report 11/25/2010 11/29/2010 Overdue/Received
2 year report 05/27/2011 05/27/2011 On Time
3 year report 05/26/2012 05/25/2012 On Time
4 year report 05/26/2013 05/29/2013 Overdue/Received
5 year report 06/25/2014 06/27/2014 Overdue/Received
6 year report 09/30/2015 09/30/2015 On Time
7 year report 07/24/2016 07/22/2016 On Time
8 year report 05/25/2017    


Contact Us

Julie Unger
Project Manager, Post-Approval Studies Program
Food and Drug Administration
10903 New Hampshire Ave
WO66-4206v Silver Spring, MD
20993-0002

Phone: (301) 796-6134
Fax: (301) 847-8140
julie.unger@fda.hhs.gov

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