Background: Return to play (RTP) assessments after ACL reconstruction attempt to identify patients with residual deficits that haven’t regained their preinjury function, in hopes of decreasing the high rate of reinjury in this population. However, the utility of common RTP assessments, including hop testing and Biodex isokinetic strength, remains to be better understood. In the adolescent population, RTP assessments commonly rely upon those used in adults with limited evidence. The purpose of the current study was to establish the performance of young healthy athletes on common RTP assessments. Methods: A prospective cohort study of 47 healthy athletes aged 12 to 16 years was performed. All athletes performed hop testing (4 components - single, triple, crossover and timed) and Biodex isokinetic strength (6 components - quadriceps and hamstring; 60, 180, 300 degrees/second). The results were compared to the contralateral leg with a deficit defined as greater than 10% less relative to the contralateral leg. Patient demographics including age, sex, BMI, and sport played, as well as the dominant and nondominant leg were recorded. Analysis was performed relative to a single extremity (total 94) to simulate the evaluation in the setting of ACL return to play. Results: A total of 17 males and 30 females were included, with 27 being 12-13 yo and 20 being 14-16 yo. Overall, at least one deficit was present in 61.7% of extremities. This was significantly more common in non-dominant (76.6%) than dominant (46.8%) extremities (p<0.001). Biodex isokinetic strength deficits were present in 55.3% of extremities, while hop testing deficits were present in 24.5% of extremities. A total of 17 extremities had deficits in both Biodex and hop testing, while 35 had isolated biodex deficits and 6 had isolated hop testing deficits. Biodex deficits were present for quadriceps strength in 18.1%, 7.4%, and 17.0% at 60, 180, and 300 degrees respectively, while deficits in hamstring strength were present in 27.7%, 11.7%, and 17.0% at 60, 180, and 300 degrees respectively. Hop testing deficits were present in 7.4% of single hop, 9.6% of triple hop, 9.6% of crossover hop, and 6.4% of timed hop testing. Conclusions: The current study demonstrates that asymmetries in strength and hop testing are common in adolescent healthy athletes. These deficits are more common for Biodex isokinetic strength testing than functional hop testing. Deficits are more likely to occur in the nondominant extremity.
Isokinetic strength testing does not predict hamstring injury in Australian Rules footballers
