Directly measured strain patterns of the anterior talofibular and calcaneofibular ligaments after isolated ATFL repair in a combined ATFL and CFL injury: A cadaver study

Background

Even though 20% of chronic lateral ankle instability results from a combined anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) injury, only the ATFL is sutured using arthroscopic ligament repair techniques. Although some biomechanical and clinical studies have proved that isolated ATFL repair yields excellent results, previous biomechanical studies were performed using systems that only allow indirect estimations. The purpose of this study was to clarify strain patterns by directly measuring repaired ATFL and CFL strain patterns on cadaveric models that underwent isolated ATFL repair of a combined ATFL and CFL injury.

Methods

The miniaturization ligament performance probe (MLPP) system was used for directly measuring the strain patterns to insert the strain gauges into the mid-substance of normal and repaired ATFL and CFL fibers in five cadaveric specimens to allow measurement of strain patterns in the axial and three-dimensional motion of the ankle.

Results

The normal and repaired ATFL showed similar strain patterns in axial and three-dimensional motions. During the axial range of motion of the ankle, the repaired CFL showed a strain pattern almost similar to that of normal CFL, but the strain increased as the plantar flexion or dorsiflexion angle increased to the maximum value of 100 at 30° plantarflexion or strain values of 17–55/100 at 15°dorsiflexion. During three-dimensional motion, the repaired CFL was under the maximum value of 100 during dorsiflexion-inversion and exhibited less strain (7–38/100) during plantar flexion-eversion.

Conclusion

The repaired CFL did not show a strain pattern that was completely consistent with a normal strain pattern; however, it did have some degree of tension similar to a normal strain pattern, even though it was not directly repaired.