Interference screw versus suture button fixation for tibialis anterior tendon transfer: a biomechanical analysis

Tibialis anterior tendon (TAT) transfer to the lateral cuneiform is commonly utilized to treat dynamic supination for relapsed clubfoot deformity. Traditional suture button fixation (SBF) may lead to skin necrosis at the button/skin interface. While interference screw fixation (ISF) would mitigate this concern, this fixation method has not been investigated in clubfoot patients. This study aims to investigate the performance of ISF versus SBF for TAT transfer in a cadaveric model. Ten matched pairs of cadaveric feet were obtained. One of each matched specimen underwent TAT transfer to the lateral cuneiform using ISF and the other underwent TAT transfer using SBF. For each ISF specimen, the tension of the transferred TAT required to bring the ankle to neutral was measured. This tension was then applied to both matched specimens using an MTS machine. Tension dissipation was measured after a 20-minute interval. In specimens with SBF, a load cell was positioned between the plantar skin and suture button to determine plantar skin pressure at the time of initial tension application. Average tension necessary to achieve neutral dorsiflexion was 49.4 N. Average tension dissipation after 20 min was significantly less in the IFS group (20 N versus 23.6 N, P = 0.02). No fixation failures occurred in either group. Average plantar foot skin pressure was 196.5 mmHg at initial tension application, exceeding thresholds for tissue ischemia. ISF allows for tendon tensioning at forces beyond those expected to result in skin necrosis with SBF with less dissipation of tension over time.