New Isokinetic Parameters For The Outcome Assessment Of Accelerated Rehabilitation After Anterior Cruciate Ligament Reconstruction

Abstract

Strengthening of muscle power and restoration of dynamic performance have been emphasized in accelerated rehabilitation after anterior cruciate ligament reconstruction (ACLR). It is necessary to find proper ways to assess the outcome of rehabilitation process, especially in the early stage for better monitoring and adjustment of the rehabilitation process. However, the evaluation of rehabilitation outcome has been confined to the simple increase of isokinetic muscle torque after surgery. PURPOSE To investigate the changes of isokinetic torque curves during the controlled ambulatory phase in patients who received rehabilitation program after ACLR with the effort of finding useful isokinetic parameters on the outcome of accelerated rehabilitation. METHODS Twenty patients with ACL reconstruction (mean age 33 years (23–47), 16 males, 4 females) were randomly divided into two training groups. One (n = 10) was accelerated training (AT) group composed of open and closed kinetic chain(CKC) exercises and the other (n = 10) was conventional training (CT) group consisting of mainly CKC and conditioning exercises. Both groups underwent each assigned exercise program during controlled ambulatory phase from 6 to 12 weeks after surgery in our facility. Various isokinetic parameters at the angular velocity of 180°/sec (peak torque, time to peak torque, angle of peak torque, average power and work fatigue ratio) were obtained at 6 and 12 weeks after surgery. As new parameters to evaluate the dynamic performance of the knee muscles, the ratio of peak torque to time to peak torque (PTR) and the ratios of peak torque to angle from starting to peak torque (PAR) were calculated to determine the changes of torque curves. RESULTS After 6 weeks of training programs, two training groups showed significantly increases of peak torque, total work and average power of knee extensor(p = 0.007 in AT vs 0.009 in CT). However, only AT group showed a significant decrease in time to peak torque (202 ± 69 → 156 ± 37msec, p = 0.024) of knee extensor during this period. PTR (0.303 ± 0.267→0.550 ± 0.327(AT), 0.256 ± 0.148→0.367 ± 0.124(CT)) and PAR (2.17 ± 1.67→3.80 ± 1.91(AT), 1.94 ± 1.00→2.54 ± 0.70(CT)) significantly increased in both training groups. So, the isokinetic time-torque curve and angle-torque curve of the knee extensor shifted to the left and upward side after training. These ratios of AT groups were significantly higher than those of CT group(p = 0.010(PTR), p = 0.005(PAR)). CONCLUSIONS AT group showed more prominent increases of PTR and PAR than CT group. We suggest the PTR and PAR as new parameters to assess the outcome of accelerated rehabilitation after ACLR in the controlled ambulatory phase.