Sonographic study of repair, gapping and tendon bowstringing after primary flexor digitorum profundus repair in zone 2.

We report sonographic findings with clinical outcomes after zone 2 flexor digitorum profundus tendon repairs in ten fingers. The tendons underwent a six-strand M-Tang core repair, no circumferential suture, and partial or complete division of the pulleys. Over 12 months after surgery and using ultrasound, we found no gapping at the repair site during finger motion. When the pulleys were divided, there was sonographic evidence of tendon bowstringing, but the bowstringing was minimal. Clinically, we did not find any fingers that displayed tendon bowstringing or had functional loss. With ultrasound examination, the repaired tendons remained enlarged over 12 months. Two patients developed heterotopic ossifications at the repair site without tendon gliding, and these required tenolysis. We conclude that the tendon repair site does not gap when a strong core suture is used in the repair without adding peripheral sutures. There is no notable tendon bowstringing clinically, though the repaired tendons have sonographic evidence of minor bowstringing. LEVEL OF EVIDENCE: III.