Comparison of modified Broström and Evans procedures in simulated lateral ankle injury.

PURPOSE

The purpose of this study was to compare the modified Broström and Evans procedures for simulated lateral ankle instability in cadaveric lower extremities.

METHODS

Six normal cadaveric ankles were loaded with inversion and internal rotation stress through the range of ankle flexion, and three-dimensional motion of the calcaneus and talus relative to the tibia were measured. An ankle stability testing device and a magnetic tracking system were used. Testing was performed in the intact condition, unstable condition after sectioning both the anterior talofibular (ATFL) and calcaneofibular ligaments (CFL), after the Gould modification of the Broström procedure, and after the Evans procedure.

RESULTS

With inversion loading, both operations resulted in a significantly more stable ankle-hindfoot complex (calcaneal-tibial) than the unstable condition, but there was restricted motion after the Evans operation from neutral to plantarflexion. Tibiotalar inversion motion approximated normal after both operations, but subtalar motion was markedly restricted in the Evans procedure throughout the range of ankle flexion. With internal rotation loading, the Broström operation stabilized the ankle-hindfoot joint complex in plantarflexion. The Evans operation improved internal rotation stability, but restricted motion in all positions. Both operations improved tibiotalar internal rotation stability, but not to normal. The subtalar internal rotation was the same as the intact condition after the Broström operation, but markedly restricted after the Evans operation through the range of ankle flexion.

CONCLUSIONS

Both operations improved ankle-hindfoot stability, but neither was successful in restoring it to normal as determined with the ankle stability testing device. The Evans procedure improved stability at the expense of creating abnormal subtalar function. The Broström operation improved stability without excessively restricting subtalar movement, but was not effective in addressing the internal rotation laxity.