Flexor tendon-to-volar plate repair: An experimental study and 3 case reports

Purpose To investigate the histology and tensile strength of flexor tendon-to-volar plate repair in a sheep model and to evaluate outcomes in 3 clinical cases.

Methods The flexor digitorum profundus (FDP) tendon of the hind limb of the sheep was cut at the ankle. The proximal end of the FDP tendon was then repaired to a distally based flap of the underlying volar plate after 2 cm of the distal FDP tendon were excised such that the distal FDP tendon was not directly in contact with the repair site. The repair was studied histologically and tested biomechanically at 8 intervals (0, 1, 2, 3, 4, 5, 6, 8, and 12 wk) following repair. Three clinical cases with flexor tendon-to-volar plate repair are presented. In all cases, the circumstances of the injury precluded the usual tendon-to-tendon repair. The first patient had a laceration of FDP in zone 1A and the other 2 patients had delayed 2-stage flexor tendon reconstruction.

Results The mean breaking strength of the tendon-to-volar plate repair was 26 N at 0 week, 62 N at 1 week, 52 N at 2 weeks, and then progressively increased to reach 312 N at 12 weeks. Histologically, thin randomly arranged collagen fibers were seen at the repair site at 3 weeks; and healing with thick parallel collagen bundles were seen at 6 weeks. Clinically, the flexor tendon-to-volar plate repairs healed without rupture. All patients obtained full active range of motion at the metacarpophalangeal and proximal interphalangeal joints. The active range of motion at the distal interphalangeal joint was 0° to 50° in 2 patients and 0° to 40° in the third patient.

Conclusions The flexor tendon can heal to the volar plate in the sheep model. Clinical relevance Suture of tendon to volar plate is an option in distal zone 1 FDP repair and FDP tendon reconstruction.