Changes in single-legged functional ability and subjective performance toward return-to-play after an anterior cruciate ligament reconstruction: Focused on the limb symmetry index

Abstract

This study presents a single-legged functional ability and subjective performance toward return-to-play (RTP) to soccer competitions after anterior cruciate ligament reconstruction. A male collegiate soccer player was assessed using the following battery of single-legged tests: single, triple, and crossover hop for distance; side hop, up-down, and figure-of-eight hop for speed; vertical single-limb hop for lower limb power; and vertical ground reaction force and center of mass pressure (COP) trajectory during forward and lateral drop landing tasks for dynamic balance. The limb symmetry index (LSI) was expressed as a ratio of the injured limb to the uninjured limb. Lower limb asymmetry appeared in single-legged hop for distance and speed tests in a prior stage of RTP. After returning to play at a low performance level, a functional deficit was shown in the single hop for distance, figure-of-eight hop for speed, and COP trajectory during lateral drop landing. In the improvement stage of subjective performance, the LSI of figure-of-eight hop was over 100 and a smooth change-of-direction maneuver with body inclination was observed in the figure-of-eight hop test. This practical study may contribute to successful return-to-play, not only in terms of safety and early return-to-play, but also performance enhancement.