Predicting Outcome After Surgery for Carpometacarpal Osteoarthritis
Authors: Spekreijse Kim , Steyerberg Ewout , Tsehaie Jonathan , Vermeulen Guus , Feitz Reinier , Slijper Harm , Hovius Steven , Selles Ruud 
Published: September 2016

Objective: Research on carpometacarpal (CMC) osteoarthritis (OA) is primarily focused on comparing surgical outcome of different techniques, in case series or comparative studies. Many studies do not demonstrate significant differences in outcome between surgical techniques. However, it has been reported that a relatively large part of treated patients have significant residual pain and functional limitations, or even deterioration of their initial complaints. Overall outcome may also be improved by selecting “the right patients” for surgical treatment. Therefore, the aim of this study is to (1) describe the outcome of widely used techniques for CMC OA in a large, multicenter cohort and (2) identify predictive factors of poor surgical outcome, defined in terms of pain, complications, hand function, and patient satisfaction to predict possible failure after surgical treatment. Materials and Methods: We included 668 patients in a multicenter, prospective study between 2011 and 2015, who were surgically treated for CMC OA with trapeziectomy with ligament reconstruction and tendon interposition (LRTI).Outcome parameters, registered preoperatively, 3 months and 12 months after surgery, included pain (visual analogue scale [VAS]), function (Michigan Hand Questionnaire [MHQ]), complications, and satisfaction with the hand. Postoperative outcomes were compared with baseline levels. Multiple imputation was performed after missing value analysis. Baseline pain, function and strength, sociodemographics, and hand surgical history were analyzed as possible predictors for outcome after surgery, by multivariate regression analysis. Results: For all measurements, outcomes improved significantly after surgery, with effect sizes greater than 0.8 for pain, total MHQ score, and patient satisfaction outcomes. However, we found a residual rest pain of 19 (VAS 0-100) after 1 year. In total, there were 327 complications in 229 patients, of which 43% required no or conservative treatment. Univariate analysis showed that only a few of the baseline variables correlated with postoperative outcome measurements at 12 months. These associated variables were combined with predictors selected from literature and were considered in multivariable analyses. For pain and the number of complications, the multivariable regression models could only explain 2% of the variance in the model. For self-reported satisfaction of the hand, this was only 5%. For the MHQ score, the multivariable regression analysis could explain 17% of the variance in the model, with a history of De Quervain tendinitis, smoking, lower baseline MHQ total score, and increased preoperative pain, independently predicting a worse postoperative MHQ score. Conclusions: After surgical treatment for CMC OA, improvements in pain, strength, and function in our study are highly significant and clinically relevant. Despite the large overall improvement, we found significant percentages of patients with unfavorable outcomes (residual pain and functional deficits) in this large cohort, which is also in line with present literature. Based on this study, we conclude that we cannot predict which patients will have bad surgical results after surgical treatment for thumb CMC OA, despite our relatively large sample of baseline characteristics and large cohort. Our study suggests that we need to look beyond the commonly evaluated predictive factors (age, gender, baseline functional scores, etc) and treatment algorithms to improve outcome of all patients with CMC OA.