A Single-Leg Vertical Hop Test Is an Effective Tool to Measure Functional Performance after Anterior Cruciate Ligament (ACL) Reconstruction

Abstract

This study evaluated the single-leg vertical hop test (SLVHT), using digital sensor technology, for the functional assessment of rehabilitation progress in patients after ACL reconstruction (ACL-R). Between January 2019 and June 2022, 143 patients (26.6 (8.9) years, m/f 66/34%) completed return-to-sport testing at 3 and 6 months after ACL-R. The jump height during SLVHT was quantified with a digital motion sensor, containing a three-axis acceleration gyroscope sensor, and the limb symmetry index (LSI) (injured/non-injured leg ratio) was calculated. Three months postoperatively, the jump height of the injured leg was 59.6% (13.5 (5.5) cm) that of the non-injured leg (22.9 (6.2) cm; p < 0.01). After 6 months, the jump height of the injured leg (18.4 (6.9) cm) improved by 44.1% compared to that at the 3-month follow-up but was still lower than the non-injured leg jump height (23.2 (7.0) cm, p < 0.001; LSI = 79.6%). Men jumped higher than women, but their LSI was not different at 3 (59.6 vs. 59.5%) and 6 months (80.6 vs. 77.8%). Regression analysis identified the non-injured leg jump height as the primary independent predictor of the jump height of the injured leg (β = 0.776, T = 51.506, p < 0.001). SLVHT, using digital sensor technology, is a simple and cost-effective functional test to assess rehabilitation progress after ACL-R, with the potential for multi-centre data analysis.