Biomechanical Evaluation of Preoperative Rehabilitation in Patients of Anterior Cruciate Ligament Injury

OBJECTIVES: To investigate the biomechanical characteristics of patients with anterior cruciate ligament (ACL) injury by gait analysis, surface electromyography (SEMG), and proprioception test, and provide rehabilitation suggestions according to the results. METHODS: In this retrospective cohort study, 90 adults with unilateral ACL injury, ranging in age from 19 to 45 years (66 men and 24 women, average age: 30.03 ± 7.91) were recruited for this study form May 2018 to July 2019. They were divided into three groups according to the time after the injury: group A (3‐week to 1.5‐month), group B (1.5‐month to 1 year), and group C (more than 1 year). The SEMG signals were collected from the bilateral rectus femoris (RF), vastus medialis (VM), and vastus lateralis (VL) and the root mean square (RMS) were used to assess muscular activity. SEMG were used to analyze muscles function, gait analysis was used to evaluate the walking stability, balance and location assessment were used to analyze the proprioception. RESULTS: Through the comparison between bilateral limbs, all muscles strength shown decreased (RF: 239.94 ± 129.70 vs 364.81 ± 148.98, P = 0.001; VM: 298.88 ± 175.41 vs 515.79 ± 272.49, P = 0.001; VL:389.54 ± 157.97 vs 594.28 ± 220.31, P < 0.001) and the division of proprioception became larger (tandem position: 7.79 ± 1.57 vs 6.33 ± 1.49, P = 0.001; stance with one foot: 8.13 ± 0.84 vs 7.1 ± 0.57, P = 0.003; variance of 30°: 6.96 ± 3.15 vs 4.45 ± 1.67, P = 0.03; variance of 60°: 4.64 ± 3.38 vs 2.75 ± 1.98, P = 0.044) in the injured side when compared to the non‐injured and 26 gait parameters were shown difference in group A. In group B, the muscle strength of VL shown decreased (VL: 381.23 ± 142.07 vs 603.9 ± 192.72, P < 0.001) and the division of location of 30° became larger (7.62 ± 4.98 vs 4.33 ± 3.24, P = 0.028) in the injured side when compared to the non‐injured side and there were eight gait parameters that showed differences. In group C, the muscle strength and proprioception showed no differences and only 16 gait parameters showed differences between the bilateral limbs. CONCLUSION: The results proved the deterioration of proprioception in 30° of injured side will not recover and non‐injury side and will become worse after 1 year from the injury; among the VL, VM, and RF, the recovery rate of VL is the slowest and bilateral straight leg raising (SLR) (30°) is the best way to train it; the gait stability will be worse after 1 year from the injury. Therefore, we suggest that the training for proprioception in 30° and VL are important for the rehabilitation, and the ACL reconstruction should be performed within 1 year.