Objective

After anterior cruciate ligament (ACL) tear, the ACL reconstruction (ACLR) is the standard treatment to return to pivots/contacts sports. The goal of rehabilitation programs is to guide the functional recovery and the safe return to sport without additional knee injury or other injuries. Functional tests, like Hop tests and their side to-side difference index [limb symmetry index (LSI)], are commonly used following ACLR to help return to sport decision making. However, the most commonly used criterion to return to sport is the postoperative time: return to light activities (RtlA) at 3 or 4 month mark and return to sport with contacts and side-cuttings (RtS) between 6 and 9 month mark.

The aim of this study was to analyse the functional recovery after ACLR using the standard hops LSI scores and compare these scores with usual timeline of RtlA and RtS.

Patients and methods

Thirty-one patients with ACLR (19 males) with a mean age of 23 ± 7 years. Functional recovery was evaluated during rehabilitation and return to sports phases (from 3 to 12 months postoperatively), with 2 straight one-legged Hop tests for distance (Single and Triple Hop tests). The LSI was calculated for each test. A non-linear regression was calculated to obtain predictive values of 3, 4, 6 and 9 months postoperatively.

Results

At 3 months, Hop tests LSI was nearly 80%, with great variability [interquartile range (IQR): 75%–95%]. At 4 months, Hop tests LSI was just under 85% but with important variability (IQR: 78%–94%). At 6 months, Hop tests LSI was about 90%, and over 90% at 9 months. From 6 postoperatively, the variability decreased (IQR: 94%–99%).

Discussion/Conclusion

Comparing our results with the usual timeline of RtlA, we can say that the timeline of 3 months postoperatively is a little too short to RtlA. At 4 months postoperatively, the functional recovery can allow a safely RtlA. At 6 months postoperatively, the LSI is greater than 90%, allowing RtS. Given the great variability between patients before 6 months postoperatively, this functional assessment could be used in association with clinical and isokinetic evaluations to individualize the decision to return to sport.