Anatomic variations of the first extensor compartment and abductor pollicis longus tendon in trapeziometacarpal arthritis

Abstract

Anatomic variation of the trapeziometacarpal joint stabilizing structures is one of the concepts proposed to explain the pathogenesis of trapeziometacarpal arthritis. We undertook this study to test the hypothesis that septation of the first extensor compartment or variation of the abductor pollicis longus (APL) tendon (supernumerary insertions) are more frequently associated with the progression or severity of trapeziometacarpal arthritis. Septation within the first extensor compartment was significantly associated with trapeziometacarpal arthritis (p = 0.013), whereas supernumerary APL insertions (trapezium or thenar) did not reveal a significant association (p = 0.811 and p = 0.937, respectively). The results of this study do not support a role for variations of APL tendon insertions in trapeziometacarpal arthritis. Yet, the presence of septation within the first extensor compartment may play an important role in the pathogenesis of trapeziometacarpal arthritis.

Figures

Figure 1

Radial view of the left hand of a specimen with full septation of the first extensor compartment. Both tendons of the compartment are in separate tunnels. The margin of the first extensor compartment was dorsally reflected (black suture) to visualize the full separation of the tendons.