The Effect of Isokinetic Exercise for Prehabilitation: ACL Reconstruction

Abstract

Preparing for the stress of Anterior Cruciate Ligament Reconstruction (ACLR) surgery through prehabilitation may improve strength and function before surgery, and if effective, has the potential to contribute to postoperative recovery. The purpose of this experimental study was to investigate the effectiveness of using isokinetic exercise for prehabilitation of patients with complete ACL tears, awaiting ACLR surgery. Patients with complete ACL tears, and scheduled for ACLR were randomized into the isokinetic exercise training group or the control group. The isokinetic exercise training group completed an isokinetic strengthening program that included isokinetic concentric exercise for the injured knee, 20 times over 8 weeks before their ACLR. The control group did not receive the treatment. Both groups were encouraged to continue any exercise or activities they were currently participating in. Leg strength (isokinetic peak torque for knee extension and flexion) was assessed before randomization at baseline (T1), again 8-weeks (T2) preoperative, and 24-weeks (T3) postoperative. In addition, at 24-weeks (T3) postoperative, the single leg hop test for distance was added as a functional measure. Following the 8-week exercise intervention, quadriceps peak torque improved (p<0.05) from baseline in the exercise group compared to the control group at all three isokinetic speeds: 60˚/sec, 120˚/sec and 180˚/sec. At 24-weeks post-surgery, quadriceps peak torque was still higher compared to the control group at two isokinetic speeds: 60˚/sec, 120˚/sec (p<0.05), and approached significance at 180˚/sec (p=.059). At 24-weeks post-surgery, quadriceps peak torque at 60˚/sec in the exercise group had ii improved from baseline measures (p<0.05) and approached statistical significance at 120˚/sec (p=.053), compared to the control group. At 24-weeks post-surgery, the exercise group performed better on the single leg hop test, than the control group (p<0.05). Participants in the isokinetic exercise group had higher quadriceps peak torque both pre- and postoperatively compared to the control group (p<0.05). This increased peak torque lead to improved function, as reflected in the single leg hop tests scores (p<0.05). These results reflect that improving quadriceps strength preoperatively contributes to stronger quadriceps postoperatively. Improved quadriceps strength postoperatively would assist patient adaptation to the rehabilitative process, as well as increase quality of life and slow the progression of osteoarthritis. The rehabilitative process may be accelerated, allowing the patient to return to sport and activity sooner, and potentially prevent re-injury. This study supports prehabilitation for patients awaiting ACLR, however further studies need to be done to develop guidelines and protocols. Longitudinal research should examine the effects of prehabilitation programs for years after ACLR and include analysis of return to sport outcomes.