Countermovement Jump and Isokinetic Dynamometry as Measures of Rehabilitation Status After Anterior Cruciate Ligament Reconstruction

Abstract

Context:  Despite an increase in the literature, few definitive guidelines are available to determine when an athlete has been fully rehabilitated after anterior cruciate ligament reconstruction (ACLR). Objective:  To examine countermovement jump and isokinetic dynamometry measures to (1) identify which measures can best distinguish between ACLR and control participants and (2) provide normative values for identified measures in young adult male multidirectional field-sport athletes. Design:  Cross-sectional study. Setting:  Orthopaedic hospital. Patients or Other Participants:  Young adult male multidirectional field-sport athletes (n = 118) who had undergone unilateral patellar-tendon graft ACLR at least 6 months earlier and healthy male participants (n = 44) with no previous knee injury. Intervention(s):  Single-legged countermovement jump (SL CMJ). Main Outcome Measure(s):  Three-dimensional biomechanical analysis of the SL CMJ and mean peak concentric knee-extension and -flexion torque using isokinetic dynamometry (ISO) were compared in the 2 groups. A stepwise logistic regression was carried out to identify the best predictors of ACLR- or control-group membership (SL CMJ height, limb symmetry index, peak power, joint power contribution, ISO peak torque, limb symmetry index variables). Results:  The control group differed strongly from the ACLR group in isokinetic knee-extension peak torque (d = –1.33), SL CMJ performance (d > 0.4), and limb symmetry measures in both ISO and jump outcomes (d > 1.1). The combination of measures from both ISO and SL CMJ identified group membership with an accuracy of 89%. Conclusions:  Rehabilitation of ACLR patients may be complete when they achieve isokinetic knee-extension peak torque of 260% (±40%) body mass, SL CMJ performance of >17 cm (±4 cm), and reach-limb symmetry measures of >90% in both strength and jump outcomes. The outcomes in the control group can inform return-to-play criteria for young adult male multidirectional field-sport athletes after ACLR.