Plastic Surgery Research Council
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PSRC 60th Annual Meeting
Program and Abstracts

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Metacarpal Subsidence following Thumb Carpometacarpal Joint Arthroplasty
Jignesh V. Unadkat, MD, MRCS, John R. Fowler, MD, Joseph E. Imbriglia, MD.
UPMC, Pittsburgh, PA, USA.

Metacarpal Subsidence Rates following Thumb Carpometacarpal Joint Arthroplasty
Background: Thumb carpometacarpal (CMC) arthritis causes significant disability in affected patients. When conservative measures have failed, various surgical options exist including simple trapeziectomy, hematoma distraction, and ligament reconstruction tendon interposition (LRTI). Post surgical metacarpal subsidence may lead to pain due to abutment on distal scaphoid, eventually leading to a weaker thumb. Anecdotal experience by the senior authors suggested that subsidence was more related to age than surgical technique. The purpose of this study was to compare the rate of metacarpal subsidence between LRTI and simple trapeziectomy with tendon interposition (TI).
Methods: An IRB approved, retrospective chart review of patients undergoing CMC arthroplasty from 2010-2013 by the senior author (JEI) was performed. Surgical technique (LRTI or TI) was performed at the surgeon’s discretion. All patients undergoing CMC arthroplasty who had hand radiographs performed pre-operatively, 2 weeks, 3 months and more than 6 months post-operatively were included. Metacarpal subsidence was evaluated as post-operative trapezial space ratio (distance from base of thumb metacarpal to scaphoid / proximal phalanx length) post-operatively compared to pre-operative evaluation. Univariate analysis for demographic factors and multivariate logistic regression analysis for factor association with >50% metacarpal subsidence performed using SPSS for Mac. Results expressed as odds ratio (95% confidence interval). P<0.05 was considered significant.
Results: 86 patients underwent CMC arthroplasty over the study period; 29 patients (31 thumbs) matched our inclusion criteria. There were 10 males and 19 females. Average age was 60 years (range 46-81 years). Long-term follow up averaged 13 months (range 6 - 35 months). On average, 2 weeks post-operatively there was 50% metacarpal subsidence that remained constant even at long-term follow-up. Eaton grade, gender, thumb laterality or type of operation were not significantly associated with >50% subsidence. Age was significantly associated with >50%subsidence [OR 1.17 (1.0092 - 1.3583)]. Controlling for type of operation age >60yrs was most associated with >50% subsidence [OR 11.0652 (1.0856 - 112.7827)].
Conclusion: This study assessed the degree of long-term metacarpal subsidence following CMC arthroplasty and the factors associated with it. Previous studies have found that surgical technique does not appear to affect outcomes or subsidence after CMC arthroplasty. The current study has found patient age as a significant independent predictor in the amount of subsidence that occurs, irrespective of technique. In carefully selected patients, performing the shorter, less complex operation may result in equivalent outcomes.


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