Return to Sport: Does Excellent 6-Month Strength and Function following ACL Reconstruction Predict Mid-Term Outcomes?

Abstract

We sought to determine if patients with excellent functional and isokinetic performance at six months had 1) higher risk of subsequent ACL tears with earlier RTS, 2) superior knee function, and 3) increased activity levels at mid-term follow-up compared to those with delayed clearance for RTS. We identified 223 patients who underwent primary ACL reconstruction by a single surgeon and had functional and isokinetic testing performed six months postoperatively. An ‘excellent’ outcome was defined as having a satisfactory result in 6 of 7 isokinetic-strength and functional-testing categories. A satisfactory result was defined as minimum 85% performance in isokinetic strength and 90% performance in functional testing compared to the contralateral knee. Of the 223 patients, 52 (23.3%) met criteria for the early RTS group, leaving 171 (76.7%) comprising the delayed RTS group. Rate of ACL-graft tear (ipsilateral) and native-ACL tear (contralateral) were compared between the groups. Additionally, minimum two-year IKDC and Tegner scores were compared. Ten (4.5%) patients had an ipsilateral graft rupture, and 17 (7.6%) had a contralateral ACL tear after mean follow-up of 3.7 years (range 2-10). The graft rupture rate was similar in the early RTS group (3.8%, n=2) compared to the delayed RTS group (4.7%, n=8; p=0.30). However, there was a higher rate of contralateral ACL tear in the early RTS group (15.4%, n=8) compared to the delayed RTS group (5.3%, n=9; p=0.003). The early RTS group had superior IKDC scores (94.3 + 6.4 vs 90.9 + 9.7; p=0.04) and Tegner scores (6.6 + 1.8 vs 5.7 + 1.6; p=0.01). Patients with an excellent performance on their isokinetic-strength and functional-testing at six months after ACL reconstruction have superior knee function and higher activity levels at mid-term follow-up. However, these patients appear to be at greater risk of contralateral ACL injury, possibly related to their increased activity level.