Effect of an accelerated ACL rehabilitation protocol on knee proprioception and muscle strength after anterior cruciate ligament reconstruction

Objective: to evaluate knee joint position sense (JPS) and muscle strength following an accelerate rehabilitation protocol after ACL reconstruction and compare it with the contralateral non-injured leg, and with an age-matched non-injured control group. Design: Seven subjects (mean age: 26.6 ± 4.8 years) submitted to ACL reconstruction (ACL group) using a patellar tendon auto-graft (bone-tendon-bone) and nine healthy individuals (mean age: 26.8 ± 3.8 years) participated in this cross-sectional study. Joint position sense was evaluated using the technique of open-kinetic chain and active knee positioning. Knee extensors and flexors muscle strength was evaluated in an isokinetic dynamometer at 180o/s (3.14 rad.s-1) and 60o/s (1.05 rad.s-1). Results: The ACL reconstruction group showed better knee JPS in the uninjured knee than in the reconstructed knee in absolute (2.17o ± 2.69o vs. 5.98o ± 2.64o, p<0.05), relative (2.17o ± 2.69o vs. 5.98o ± 2.64o, p<0.05), and variable angular errors (2.38 ± 1.15o vs. 2.01 ± 1.64, p<0.05). The reconstructed knee also exhibited inferior JPS than both limbs of the control group. No significant differences in quadriceps and hamstrings muscle strength were observed. Significant contralateral differences between ACL and control group were found for knee extensors at 60o/s (33.6 ± 18.0 vs. 5.9 ± 7.1%, p<0.05) and 80o/s (20.2 ± 13.5 vs. 5.8 ± 3.9%, p<0.05), and knee flexors at 60o/s (16.2 ± 6.4 vs. 8.5 ± 5.0%, p<0.05). Conclusions: Our findings indicate that joint position sense and muscle function is still impaired after an accelerate rehabilitation protocol for ACL reconstruction surgery suggesting that these individuals are still predispose to further muscle or proprioceptive related knee injury.