Association of the Single-Limb Hop Test With Isokinetic, Kinematic, and Kinetic Asymmetries in Patients After Anterior Cruciate Ligament Reconstruction

BACKGROUND Asymmetries persist after anterior cruciate ligament reconstruction (ACLR). Physical performance tests such as the single-limb hop test have been used extensively to assess return-to-sport criteria, as they reproduce dynamic athletic maneuvers. HYPOTHESIS The single-limb hop is associated with muscle strength and kinematic and kinetic asymmetries in ACLR patients 6 to 9 months after surgery. STUDY DESIGN Controlled laboratory study. METHODS Twenty-two men with ACLR (mean age, 28.8 ± 11.2 years) at 6 to 9 months (mean, 7.01 ± 0.93 months) after surgery completed isokinetic testing in 3 velocities (120, 180, and 300 deg/s) and a kinetic, kinematic, and functional evaluation of the single-limb hop test. Pearson correlation coefficients were used to assess the relationship between the Limb Symmetry Index (LSI) of the single-limb hop distance and each of the outcome variables. RESULTS There were significant positive correlations between the LSI of the single-limb hop distance and the LSI of the peak extension torque at 120 deg/s (P = 0.044, r = 0.37) and the peak extension torque at 180 deg/s (P = 0.042, r = 0.38) as well as a negative correlation with the peak flexion torque at 180 deg/s (P = 0.043, r = -0.38). The LSI of the single-limb hop test was not correlated with any kinetic or kinematic variable (P > 0.05). CONCLUSION The findings of the present study demonstrate that distance LSI of the single-limb hop test correlates with isokinetic extension peak torque LSI but not kinetic and kinematic asymmetry. CLINICAL RELEVANCE The single-limb hop test can be used as an additional tool for the recognition of muscle strength asymmetries but not for kinetic or kinematic asymmetries 6 to 9 months after ACLR.