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.
1Department of Orthopaedic Surgery, Takai Hospital, Tenri, JAPAN; 2Department of Orthopaedic Surgery, Mayo Clinic, Rochester, MN; 3Department of Orthopaedic Surgery, Sapporo Medical University, Sapporo, JAPAN; 4Department of Orthopaedic Surgery, Baylor College of Medicine, Houston, TX; and 5Orthopaedic Biomechanics Laboratory, Mayo Clinic, Rochester, MN
Address for correspondence: Harold B. Kitaoka, M.D., Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905; E-mail: firstname.lastname@example.org.
Submitted for publication November 2004.
Accepted for publication November 2005.