Comparison of dominant and non-dominant knee kinetics in healthy controls versus anterior cruciate ligament reconstruction.

Purpose/Hypothesis: To examine the knee joint loading with anterior cruciate ligament reconstruction (ACL-R) of the dominant (ACL-D) or non-dominant (ACL-ND) limb at the time of return to sport (RTS) compared to matched healthy controls (CON). Subjects: A total of 150 athletes volunteered. (ACL: N=75, Age=15.56±1.74yrs, Ht=167.93±9.77cm, Mass=67.22±11.39Kg; CON: N=75, Age=15.52±1.91yrs, Ht=168.84±8.33cm, Mass=63.74±11.61Kg). Participants in the ACL-R group underwent ACL-R with a patellar BTB or hamstring graft and were assessed at time of RTS. All subjects in the CON group were considered healthy with no history of lower extremity injury in 3 months prior to testing and IKDC ≥ 95. Materials/Methods: Lower extremity 3-D joint angles and ground reaction force data were collected using an 8 three-dimensional Motion Capture System and force plates. Participants performed 5 double-leg squats (DLS) at a standardized speed (60 bpm). Peak knee extension moment (KnEXTmm) was calculated during the descent phase. Knee joint energy absorption (KnEA) and knee joint energy absorption contribution (KnEAC) were calculated during the same phase. These variables were normalized to the participant's height and weight and averaged across the middle 3 trials. Finally, peak quadriceps (QUADS) isokinetic strength at 60°/sec was assessed, normalized to body weight, and averaged across 3 trials. Separate ANOVAs were performed to examine difference between groups. Comparisons were made between those with ACL-D and the dominant limb of the CON-D and between those with an ACL-ND and the non-dominant limb of CON-ND. Results: In both the ACL-D and ACL-ND groups, KnEA (ACL-D=-0.04±0.02, CON-D=-0.05±0.02; p=0.016. ACL-ND=-0.04±0.01, CON-ND=-0.05±0.01; p< 0.001) and QUADS (ACL-D=1.36±0.51, CON-D=1.79±0.45; p=0.001. ACL-ND=1.40±0.38, CON-ND=1.69±0.41; p=0.001) were significantly decreased compared to controls. KnEAC (ACL-D, CON-D; p>0.05. ACL-ND=51.73±12.54, CON-ND=60.93±9.83; p< 0.001.) and KnEXT mm (ACL-D, CON-D; p>0.05. ACL-ND=-0.04±0.01, CON-ND=-0.05±0.01; p=0.00.) were significantly decreased in the ACL-ND group compared to CON-ND. Significant differences were not observed for these variables between the ACL-D and CON-D groups (p>0.05). Conclusion: Non-significant difference in KnEAC and KnEXTmm in the ACL-D group indicates these subjects performed DLS task at the level observed in the healthy population. However, the significant difference in KnEA in the ACL-D group indicate an overall lower level of loading on the involved limb. All other variables, regardless of side of injury, the ACL-R groups exhibited significantly decreased kinetic and muscle performance relative to healthy controls indicating that side of dominance had little influence on knee biomechanics during DLS at RTS. Clinical Implication: Clinicians should take into consideration which limb underwent ACL-R when designing rehabilitation programs and be aware of these kinetic deficits at the knee joint and attempt to address these differences prior to time of return to sport.