Comparative analysis of quadriceps and hamstring strength and limb circumference between operated and non-injured legs after anterior cruciate ligament reconstruction in recreational athletes

Purpose: The aim of our study was to compare the thigh muscle strengths between the operated and non-injured legs and to evaluate the hamstring/quadriceps (H/Q) ratios by the isokinetic dynamometer at different angular velocities, in individuals with unilateral interior cruciate ligament (ACL) surgery. Material and Methods: Five female and fifteen male recreational athletes with a single-limb ACL operation within the last 1 year enrolled in the study. After physical examination, thigh circumferences were measured. Isokinetic testing of the hamstring and quadriceps were performed at different angular velocities. Peak torque and H/Q ratio values were evaluated from the isokinetic data, and the relation between leg circumference differences were analyzed. Results: The isokinetic extension and flexion muscle strengths at 60, 180, and 240°/sec (19.4 ± 11.5%, 16.6 ± 13.2%, 17.4 ± 13.2% higher in extension, 17.9 ± 14.5%, 19.7 ± 15.9%, 21.9 ± 17.4% higher in flexion, respectively) and the 10cm and 15cm above the patella circumferences were significantly higher in non-injured leg than operated leg. The extension fatigue index was significantly higher in the non-injured leg(30.6±9.5%) than operated leg (24.7±10.9%). In the operated leg, significant correlation was found between flexion peak torque at 60°/sec and flexion fatigue index. Conclusion: The decreases in peak strengths indicate atrophy of the thigh muscles in the operated leg. The muscle atrophy will lead to imbalance and may cause complications. In the post-operative period, it is important to detect the deficit with an isokinetic dynamometer and organize appropriate treatment protocols at early stages to enable the patient to regain their preoperative health.