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Carpal Instability in the Setting of Revision Thumb Carpometacarpal Arthroplasty
Austin Beason, MD; Arman Tabarestani, BS; Catalina Báez, MD, MPH; Kevin Root, BS; Anton Khlopas, MD; Trevor Simcox, MD; Aimee Struk, MEd, MBA, LAT, ATC; Richard Hutchison, MD; Paul Dell, MD; Jongmin Kim, MD
University of Florida College of Medicine, Gainesville, FL
INTRODUCTION: Trapeziectomy for thumb carpometacarpal (CMC) arthritis disrupts the scaphotrapezium-trapezoidal (STT) ligament complex and may cause carpal collapse and dorsal nondissociative carpal instability (CIND-DISI), which has been linked to poorer clinical outcomes. The purpose of this study was to evaluate the radiographic outcomes, risk factors, and prevalence of carpal instability in patients requiring revision carpometacarpal arthroplasty. MATERIALS & METHODS: A retrospective chart and radiographic review was performed on all wrists that required surgical revision following a trapeziectomy with or without suspensionplasty or ligament reconstruction and tendon interposition for thumb CMC arthritis from 2002 to 2023. Preoperative radiographs taken immediately prior to index surgery and revision were assessed for and compared using the radiolunate (RL), radioscaphoid (RS), and scapholunate (SL) angles as well as the modified carpal height ratio (MCHR). RESULTS: A total of 39 wrists met inclusion criteria with mean time-to-revision of 15.5 months and mean age at revision of 56.8 years-of-age. There was a significant difference in prevalence of DISI between Stages I-II and Stages III-IV at the time of index (0% vs 58.3%) and revision surgeries (6.7% vs 70.8%) (
p <0.001), but no significant change in prevalence within those groups over time (
Table 1). The mean change in RL angle was 5.09
o of increased dorsal tilt (
p = 0.023), while the mean changes in RS and SL angles were insignificant (
Table 2) consistent with a CIND-DISI pattern. The mean MCHR decreased 0.04 from time of index to revision surgery (
p <0.001). Age at revision, smoking status, and time-to-revision were not identified as predictors of developing carpal instability. CONCLUSIONS: Despite no significant increase in prevalence of carpal instability, there is a significant progression of lunate extension with preservation of SL relationship (
i.e., CIND-DISI) and carpal collapse between initial trapeziectomy procedure and subsequent revision. In the setting of revision CMC arthroplasty, progression of carpal instability is independent of time and other patient factors, however, Stage III and IV arthritis is associated with higher rates of CIND-DISI at time of revision. Further study is needed to evaluate the clinical implications of carpal instability in patients with failed CMC arthroplasty.
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