Differential Splinting After Zone II Flexor Tendon Repair: The Bidirectional Splint

Zone II flexor tendon injuries remain challenging because of the risks of rupture, adhesions, and stiffness. Splint design may influence repair-site tension during early healing. We describe a novel bidirectional splint (B-splint) that applies differential tensioning and compare its outcomes with those of conventional dorsal blocking splinting.

We retrospectively studied 59 patients (99 repaired tendons): 20 patients (31 tendons) treated with the B-splint after flexor digitorum profundus repair and 39 patients (68 tendons) treated with a dorsal blocking splint. The B-splint positions repaired digits in metacarpophalangeal flexion with interphalangeal extension while maintaining the noninjured digits in full extension. Functional outcomes were assessed using the modified Strickland score; tendon rupture and tenolysis were recorded. Categorical outcomes were compared using exact tests.

No ruptures occurred in the B-splint cohort versus 1 in the control cohort. Excellent outcomes occurred in 19 of 20 B-splint patients (95%) versus 30 of 39 controls (77%), favoring the B-splint without statistical significance (P = 0.141). Tenolysis was less frequent with the B-splint (5% versus 13%). No B-splint patients developed stiffness of the noninjured digits.

The B-splint was associated with favorable functional outcomes, no observed ruptures, and less tenolysis than conventional dorsal blocking splinting. It complements established rehabilitation strategies. Prospective studies are warranted to define its biomechanical and clinical role.