Correlation among Knee Muscle Strength and Self-Reported Outcomes Score, Anterior Tibial Displacement, and Time Post-Injury in Non-Coper Anterior Cruciate Ligament Deficient Patients: A Cross-Sectional Study

Little attention has been paid to knee muscle strength after ACL rupture and its effect on prognostic outcomes and treatment decisions. We studied hamstrings (H) and quadriceps (Q) strength correlation with a patient-reported outcome measures score (International Knee Documentation Committee, IKDC), anterior tibial translation (ATT), and time post-injury in 194 anterior cruciate ligament deficient patients (ACLD) who required surgery after a failed rehabilitation program (non-copers). The correlation between knee muscle strength and ATT was also studied in 53 non-injured controls. ACLD patients showed decreased knee muscle strength of both the injured and non-injured limbs. The median (interquartile range) values of the H/Q ratio were 0.61 (0.52–0.81) for patients’ injured side and 0.65 (0.57–0.8) for the non-injured side (p = 0.010). The median H/Q ratio for the controls was 0.52 (0.45–0.66) on both knees (p < 0.001, compared with the non-injured side of patients). The H/Q, ATT, and time post-injury were not significantly correlated with the IKDC score. ATT was significantly correlated with the H/Q of the injured and non-injured knees of patients, but not in the knees of the controls. Quadriceps strength and H/Q ratio were significantly correlated with ATT for both limbs of the patients. IKDC score correlated significantly with the quadriceps and hamstrings strengths of the injured limb but not with the H/Q ratio, ATT or time passed after injury.

Effect of Fatigue on Hip and Knee Joint Biomechanics in Anterior Cruciate Ligament Deficient Patients

The influence of fatigue on landing biomechanics in anterior cruciate ligament deficient (ACLD) patients is poorly understood. The purpose of this study was to examine the effect of fatigue on hip and knee joint biomechanics in deficient patients. Twelve ACLD males and 12 healthy control subjects participated in the study. The ACLD patients landed with increased peak knee flexion angle (F = 15.71, p < .01) and decreased peak knee flexion moment (F = 9.13, p < .01) after fatigue. Furthermore, ACLD patients experienced lower vertical ground reaction forces compared with controls regardless of fatigue state (F = 9.75, p < .01). It seems that ACLD patients use protective strategy in response to fatigue in order to prevent further injury in knee point.