The Role of the Flexor Carpi Radialis Groove in Trapeziometacarpal Osteoarthritis.

Abstract

Thumb carpometacarpal (CMC) osteoarthritis (OA) is a common condition. The contribution of surrounding ligaments and tendons to the stability of the CMC joint is likely altered in OA. The flexor carpi radialis (FCR) tendon runs in the trapezial FCR groove and is often noted to be frayed during CMC arthroplasty. We hypothesized that decreased integrity of the FCR tendon is related to FCR groove morphology and is associated with increased severity of CMC OA. We examined 3-dimensional surface models based on computed tomography (CT) scans of explanted trapezia from patients who underwent thumb CMC arthroplasty. Fraying of the FCR tendon was rated intraoperatively. Measurements were taken of the FCR groove to evaluate its morphology. Preoperative thumb CMC radiographs for each patient were scored using the modified Eaton classification system and the Thumb Osteoarthritis Index. Differences in the tendon groups were examined, and multivariable linear regression models were used to test the association between tendon group and FCR groove measurement. There were 136 patients who were categorized into 4 tendon groups: intact, minor fraying, fraying, and ruptured. There were no differences between the tendon groups on any measures. Our findings do not demonstrate a significant influence of FCR groove morphology on FCR tendon fraying in CMC arthroplasty patients. We also did not find a significant association between the FCR tendon state and degree of radiographic CMC OA. Further studies should investigate the in vivo FCR tendon to evaluate its tearing and inflammation in relation to basilar thumb pain.