In January 2005, the oversight responsibility of the Post-Approval Studies Program was transferred to the Division of Epidemiology (DEPI) of the Office of Surveillance and Biometrics (OSB)/Center for Devices and Radiological Health (CDRH).
The CDRH Post-Approval Studies Program encompasses design, tracking, oversight, and review responsibilities for studies mandated as a condition of approval of a premarket approval (PMA) application, protocol development product (PDP) application, or humanitarian device exemption (HDE) application. The program helps ensure that well-designed post-approval studies (PAS) are conducted effectively and efficiently and in the least burdensome manner.
CDRH has established an automated, internal tracking system that efficiently identifies the reporting status of active PAS studies ordered since January 1, 2005 based on study timelines incorporated in study protocols and agreed upon by the CDRH and applicants. This system represents CDRH's effort to ensure that all PAS commitments are fulfilled in a timely manner.
In addition, CDRH launched this publicly available webpage to keep all stakeholders informed of the progress of each PAS. The webpage displays general information regarding each PAS, as well as the overall study status (based on protocol-driven timelines and the adequacy of the data) and the applicant's reporting status for each submission due.
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.
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.]
minimum 125 patients (STAR Ankle recipients)
The comparison of the STAR ankle is to a literature
control, in Haddad et al. , 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.  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.  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 220.127.116.11
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)
Radiographic endpoints (assessed by Anterior-posterior and lateral x-ray images of the treated ankle)
All adverse events, including information concerning the nature, onset, duration, severity, and relationship to the device and operative procedure