No correlation between trapeziometacarpal arthritis and abductor pollicis longus insertion

The primary hypothesis of this study is that supernumerary slips of the abductor pollicis longus (particularly those slips inserting distal to the trapeziometacarpal joint) increase the risk of trapeziometacarpal osteoarthritis on account of increased transarticular forces. Other hypotheses surmised that age and female gender were directly correlated with severity of arthritis. We did cadaveric dissection of the distal first dorsal compartment in 61 specimens, noting the cadaveric age, gender, and number and insertion sites of abductor pollicis longus tendon slips. Each variable was statistically correlated with visual grade of trapeziometacarpal arthritis. The median number of abductor pollicis longus tendon slips in these cadaveric hands was three (range, 1-4). Seventy-nine percent of the hands had a digastric-type insertion into the abductor pollicis brevis. Ninety percent had an insertion into the trapezium. All hands possessed an insertion into the base of the first metacarpal. Age and female gender were directly correlated with severity of arthritis. No other correlations existed. We conclude that trapeziometacarpal joint arthritis progresses with age and occurs independently of any aspect of abductor pollicis longus insertion. Based on our results, we do not recommend surgical release of these supernumerary abductor pollicis longus tendon slips for the treatment of trapeziometacarpal osteoarthritis.