Functional hop tests contribute to safe return to sports after anterior cruciate ligament reconstruction

In this chapter we examine ways to evaluate the potential for injury free return to competitive sports by evaluating athletes who had undergone ACL reconstruction and already returned to previous sport activities. We sought to identify the relationship among various hop tests scores, muscle strength, and self reported outcomes. The subjects were 15 collegiate athletes (8 men, 7 women; age, 20.5 years ± 1.2) who had successfully undergone primary ACL reconstruction with a hamstring autograft 9–12 months (10.0 ± 1.6) previously. Paticipants completed a self-report questionnaire and underwent one-legged hop tests and isokinetic strength measurements. A paired t-test was used to test for side-to-side differences in each of the hop tests, as well as for isokinetic strength. A Pearson’s product–moment correlation coefficient was used to examine the relationship among all measurements. The subjects in our study had a mean clinical outcome score of 90.1, which is considered to be indicative of normal knee function. The hop distance in the operative limb was significantly shorter than that in the nonoperative limb (p <0.01). The extention torque in the operative limb was also significantly lower than that of the nonoperative limb (p <0.01). We found a significant correlation between extention torque and hop distance (p <0.01). This study demonstrates that deficits in hopdistance and quadriceps strength persist at 9–12 months after ACL reconstruction, even after a return to sports activities. To optimize functional and clinical outcomes and a safe return to sports, we propose to use evidence based medicine (EBM) assessments with functional practice, hop tests, and isokinetic strength tests, with an emphasis on evaluating side-to-side assymmetry.