Outcomes 2 Years After ACLR In Athletes: Function, Return To Sport Rates, And Re-Injury Rates From The Delaware-Oslo ACL Cohort Study

OBJECTIVES: At least 175,000 Anterior Cruciate Ligament Reconstructions (ACLR) are performed yearly in the United States, with the goal of restoring static knee stabilization for full return to previous level of function. Large data registries have reported general population outcomes after ACLR, but less is known about the athletic population. The purpose of this study is to evaluate functional outcomes, return to sport rates, and re-injury rates 2 years after ACLR from an all athlete cohort and make comparisons to outcomes reported in the literature. METHODS: Three hundred subjects were prospectively enrolled after ACL injury. All subjects sustained an isolated ACL injury and were enrolled within 7 months of injury. Subjects regularly participated in level I or II sports greater than 50 hours per year. All subjects underwent preoperative neuromuscular training. 201 of these subjects underwent ACLR. 157 patients returned for follow-up 2 years after surgery for performance-based and patient-reported testing. Quadriceps strength testing was completed either isometrically or isokinetically using an electromechanical dynamometer, and reported as quadriceps index (QI) [involved/uninvolved x 100]. Patient reported measures included The International Knee Documentation Committee 2000 Subjective Knee Form (IKDC2000), return to pre-injury activity (RTS), return to pre-injury activity competitive level (RTS-L), and re-injury. Statistics are expressed in means and standard deviations with T-tests or Chi-square for comparisons with values reported in literature. RESULTS: Two year follow up QI (mean±SD: 96.94±13.4%) revealed significantly higher quadriceps index compared to Hamada 2001 (89.8±16.5%) (P<.001). IKDC2000 (90.40±11.0; median: 94) scores were higher than the median score reported by the MOON group at 2 years (median: 75). Our RTS (72%) was significantly higher than Arden et al. 2014 (65%) (P=.012), whereas, our RTS-L (55%) was similar to Arden 2014 (55%) (P=.997). Our Re-injury rate was 13.9% (19 ipsilateral, 9 contralateral) which was significantly less (P=.002) than Paterno 2014 (29.5%). CONCLUSION: A comprehensive pre-operative rehabilitation program including neuromuscular training, combined with a post-operative rehabilitation program resulted in higher quadriceps strength, return to sport rates, and re-injury rates in athletes 2 years after ACLR compared to recent findings in the scientific literature. These findings highlight that despite excellent clinical outcomes, ACLR does not guarantee return to sport, and re-injury rates remain high. Limitations include motivational differences in athletes compared to general populations as well as age differences compared to Paterno 2014. Further research is needed to determine how to improve return to sport competitive levels rates and reduce subsequent injury risk in athletes after ACLR.