Extensor tendon repair with and without central slip reattachment to bone: a biomechanical study

Swanson's technique for repair of the extensor tendon of the proximal interphalangeal (PIP) joint, entailing bony reattachment of the extensor tendon to the base of the middle phalanx, is a common procedure. We introduce a repair technique that is less complicated and that may be equally appropriate for approach to the PIP joint. The extensor tendon is incised longitudinally directly over the PIP joint. The insertion of the central slip and capsule are elevated off of the base of the middle phalanx. This allows excellent visualization of the PIP joint. The extensor tendon is then repaired by side-to-side approximation using Ethibond suture. The purpose of this study was to test and compare the strength of this proposed technique with that of Swanson in a cadaver model.

The index, long, and ring fingers from 4 pairs of fresh-frozen cadaver hands were harvested (24 digits total). One technique was performed and tested in all digits of the 3-digit contralateral pairings from 2 pairs of hands (3 digits x 4 hands; 12 digits total per technique). Twelve control digits were used to measure the fixation strength and stiffness of the Swanson approach, and the other 12 digits were used to measure the fixation strength and stiffness of the new procedure.

All tendon repairs tolerated physiologic loading of 25 N. There was no statistically significant difference in stiffness between the control and experimental groups (mean +/- SD, 4.74 N/mm +/- 0.46 and 4.62 N/mm +/- 0.30, respectively; p >.05).

Simple repair of the central slip without reattachment to bone preserves the function of the extensor mechanism at the PIP joint and provides excellent exposure to the joint.