bowstringing

Bowstringing is the loss of the normal close apposition of a flexor tendon to the volar surface of the phalanges, occurring when the constraining annular-pulley system is disrupted, surgically released, or congenitally absent. The clinical effect derives from basic biomechanics: an intact pulley system holds the tendon along a curved path that maximises the moment arm at each joint; pulley loss permits the tendon to take a chord across the joint, shortening the moment arm and reducing flexion strength. Partial venting of A2 within millimetre-scale edge limits, and complete venting of A4, do not produce clinical bowstringing in published series; complete release of A2 remains contraindicated. Late-onset bowstringing after primary repair is a surgical complication rather than a sequela of healing and indicates pulley reconstruction.