A Smaller Operation for CMC OA of the Thumb May Not Add Up

What’s the Claim?

A prospective “patient-choice” comparative study found a small operation (denervation of the CMC joint for arthritis) little different from a large one (suspension arthroplasty) in terms of pain and patient-reported outcomes scores. The authors also reported one large difference — a much shorter recovery time (3.3 weeks vs 4.5 months) favoring the denervation group. A total of 91% of the patients who were accounted for reported improvements in pain, 79% reported improvements in function, and 3% (one of 34 who had the procedure, though they don’t say how many were lost) underwent a suspension arthroplasty after denervation for recurrent pain. Incision-site numbness was experienced by 23% of patients, and numbness along the distal aspect of the thumb in the distribution of the dorsal sensory branch of the radial nerve occurred in 11%. The authors here opted to use this somewhat-unusual study design because another study on the topic began as a randomized trial, but investigators changed it to a “patient-choice” comparative study when too many patients dropped out after being randomized to the larger operation.

How’s It Stack Up?

In that other study, which followed patients for years rather than months (as was the case here), 26% of patients who underwent denervation came back and underwent trapeziectomy. This points to one of several issues with the current study’s design — insufficient follow-up duration to make strong claims. Another is insufficient completeness of follow-up. Normally, in a reconstructive study, one would want a minimum follow-up of some reasonable period (let’s say a year), and the authors should indicate what proportion of the patients were lost before then, since the missing generally are doing worse than the accounted for. Here, the mean follow-up in both groups was less than a year, suggesting that some (perhaps many) were not accounted for a year after surgery. That other study didn’t mention numbness as a complication, which suggests problems in the reporting there (some patients inevitably will experience this), and the study we’re commenting on here didn’t report on how bothersome that numbness was or whether it resolved.

What’s Our Take?

We’re leery of this one. While it’s tempting to have a small operation to do a big job, both this study and the other one (which are the two “best” on the topic, and the only comparative studies) have real soft spots. Denervating joints can have unintended consequences, the benefits of this procedure may be short-lived, and denervation procedures of other joints have had a mixed track record. The biggest issue, of course, is that allowing patients to self-select treatments in this context drives a strong placebo effect. When that wears off, as the longer-term study suggested it does in a high proportion of patients, it may turn out that for patients with CMC arthritis, less is less, rather than more. If you’ve got a patient who prefers a short recovery to an operation that’s been proven reliable (suspension arthroplasty), denervation may be on the menu — emphasis on may — provided (s)he has a high tolerance for uncertainty.

Source

Hustedt JW, Deeyor ST, Hui CH, Vohra A, Llanes AC, Silvestri BL. A Prospective Clinical Trial Comparing Denervation With Suspension Arthroplasty for Treatment of Carpometacarpal Arthritis of the Thumb. J Hand Surg Am. 2023;48:348-353.

Further Commentary

A short audio commentary by Jeff Stepan, MD, is available here.