Quadriceps and Hamstring Strength Symmetry After Anterior Cruciate Ligament Reconstruction: A Prospective Study
in Journal of Sport RehabilitationObjectives: To evaluate change in involved and uninvolved quadriceps and hamstring strength and limb symmetry indices (LSI) in regular intervals over the first 6 months following anterior cruciate ligament reconstruction (ACLR). Design: Prospective cohort study. Participants: Thirty-eight male participants (mean age: 24.2 [6.4] y, mean body mass index: 23.6 [4.2] kg/m2), who underwent ACLR were included. Main Outcome Measures: Isometric strength testing of the quadriceps and hamstring muscles was performed at 1, 2, 3, and 6 months after ACLR. Quadriceps and hamstring peak torques for each limb and LSI were calculated. Repeated-measures analysis of covariance and paired t tests were used to evaluate changes in strength over time and between limbs, respectively. Results: Quadriceps and hamstring peak torques of the involved limb consistently increased between each time point from 1 to 6 months (P < .001 and P = .01, respectively), whereas the uninvolved limb values did not change after ACLR (P > .05). In addition, uninvolved limb peak torque values were higher than involved limb values at each time point after ACLR for both the quadriceps and hamstrings (all P < .01). At 6 months after ACLR, 28.9% of participants demonstrated LSI greater than 90% for quadriceps strength, 36.8% demonstrated LSI greater than 90% for hamstring strength, and 15.8% of participants demonstrated greater than 90% LSI for both quadriceps and hamstring strength. Conclusions: Participants demonstrated a consistent increase in quadriceps and hamstring strength of the involved limb, with no notable change in uninvolved limb strength over the 6 months after ACLR. However, at 6 months after ACLR, only approximately 16% of participants demonstrated both quadriceps and hamstring strength LSI greater than 90%, the typically recommended cutoff value for return to sport.
Harput and Tunay are with the Faculty of Physical Therapy and Rehabilitation, Hacettepe University, Ankara, Turkey. Ithurburn is with the Department of Physical Therapy and Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, AL, USA.
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