Unicortical Versus Bicortical Screws for Dorsal Plate Fixation of Phalangeal Fractures.

Purpose: To compare unicortical and bicortical screw fixation for dorsal plating of extra-articular proximal phalangeal fractures.

Methods: Midshaft osteotomies were performed on 21 cadaveric proximal phalanges. The phalanges were fixed via dorsal plating using either unicortical or bicortical locking screws and subjected to a three-point bending test. Cyclical loading was performed, increasing displacement by 0.4 mm every block of five cycles, until construct failure. Clinical failure was defined as 2 mm of displacement. Data collected included maximal force at failure, force at clinical failure, number of cycles to failure, and displacement to failure.

Results: Similar values were noted in maximal force at clinical failure and biomechanical failure, number of cycles to failure, and displacement to failure between phalanges fixed using unicortical or bicortical locking screws.

Conclusions: Both unicortical and bicortical locking screws provide sufficient stability to facilitate early motion without risk of clinically relevant displacement during plate fixation of midshaft proximal phalangeal fractures.

Clinical relevance: Unicortical dorsal plate-screw constructs should be considered, where appropriate, to prevent tendon injury or complications.