Dorsoradial ligament reconstruction versus imbrication for restoring trapeziometacarpal joint stability: a comparative biomechanical study

The unique saddle articulation of the trapeziometacarpal joint allows for a wide range of motion necessary for routine function of the thumb. Inherently unstable characteristics of the joint can lead painful instability. In this study, we modified a surgical dorsal ligament reconstruction technique for restoring trapeziometacarpal joint stability. We evaluated and compared the biomechanical efficacy of our reconstruction technique with that of dorsoradial capsulodesis by creating a cadaveric model of rotational instability. Twenty-four specimens were subjected to dorsoradial capsulodesis (n = 12) or dorsoradial ligament reconstruction using the abductor pollicis longus (APL) (n = 12). The modified dorsoradial ligament reconstruction entailed detaching one distally based slip of the APL. The harvested tendon's proximal end was passed through a bone tunnel created at the dorsoradial ridge of the trapezium. A suture anchor was inserted at the dorsal base of the metacarpal bone. The tendon stump was sutured to the metacarpal bone using fiber wire in figure-of-eight configuration. The load to failure of the trapeziometacarpal joint under compression was higher in the reconstruction group (p = 0.003). The improvement in the rotational arc (observed in all specimens) was significantly greater in the reconstruction group than the capsulodesis group (p = 0.003). Our technique reconstructs only the necessary ligament, requires a smaller incision and relatively simpler surgical procedure, and enables precise determination of the insertion and exit sites of the tendon, making it a promising treatment for trapeziometacarpal joint instability.