Effect of Tendon Strip (FCR vs APL) on Outcome of CMC Thumb Joint Arthroplasty With Pyrocarbon Disk Interposition

Background: Pyrocarbon disk interposition for carpometacarpal (CMC) thumb joint osteoarthritis can be performed with a flexor carpi radialis (FCR) or abductor pollicis longus (APL) tendon strip. With the FCR technique, a ligament reconstruction is performed in addition to disk fixation, whereas with the APL technique the disk is simply secured in place. Our aim is to compare long-term postoperative outcomes between both techniques. Methods: In this observational study, we included 106 patients in 2 centers operated on between 2006 and 2011. We assigned patients to the FCR group or the APL group based on the respective tendon strip used. As a primary outcome, we analyzed postoperative key pinch. In addition, we analyzed postoperative tip pinch and tripod pinch, grip strength, range of motion, thumb height maintenance, and patient-reported outcome measures (PROMs). Results: The analysis showed clinically important stronger key pinch for the APL group (β = 1.28 kg). Tip pinch and grip strength showed higher outcome for the FCR group (β = 1.22 kg and 5.14 kg, respectively). Palmar abduction was in favor of the FCR group and opposition in favor of the APL group, but these were interpreted as not clinically relevant. Radiological thumb height maintenance and PROMs showed no clinical difference. Conclusions: Pyrocarbon disk interposition arthroplasty for CMC thumb joint osteoarthritis can be secured with an APL or FCR tendon strip. At long-term follow-up, use of an APL tendon strip results in significantly higher key pinch and better opposition. Tip pinch, grip strength, and palmar abduction were better after use of the FCR tendon strip. The choice of the tendon strip can be based on outcomes considered most important for the individual patient.