Rauh, Mitchell J.

Objectives: The ability of current return to sport (RTS) criteria to identify young, active patients after ACL reconstruction (ACLR) independently, at high risk for future ipsilateral or contralateral ACL injury is limited. The purpose of this study was to determine if meeting current, standard RTS criteria collectively, or in part, would identify young athletes at risk for an ipsilateral or contralateral ACL injury after primary ACLR and RTS. The tested hypothesis was the likelihood of an ipsilateral or contralateral 2nd ACL injury in the first 2 years after RTS would be the same in groups that successfully met or failed to meet all RTS criteria prior to RTS. The second hypothesis was that quadriceps femoris strength at the time of RTS would identify which limb was at greatest risk for future ACL injury. Methods: One hundred eighty-one patients (116 female) with a mean age of 16.7±2.9 years old underwent ACLR and were released to return to pivoting/cutting sports. These patients were enrolled in a prospective, observational cohort study, completed a RTS assessment and were tracked for occurrence of an ipsilateral graft tear or contralateral ACL injury after ACLR for 24 months. The RTS assessment included 6 tests: isometric quadriceps strength, 4 functional hop tests and the International Knee Documentation Committee (IKDC) patient reported outcome survey. Limb symmetry index (LSI) was calculated for strength and hop test assessments [(inv/uninv)*100]. Subjects were classified into groups that successfully passed all 6 RTS tests at a level of 90 compared to those that failed to meet all 6 criteria. Chi Square tests and Fisher Exact Tests were used to determine if successfully passing all 6 RTS measures resulted in a reduced risk of 2nd ACL injury in the first 24 months after RTS as well as to assess if ability to successfully pass individual RTS criteria resulted in reduced risk of 2nd ACL injury. Results: Thirty-nine (21.5%) patients suffered a 2nd ACL injury with 18 ipsilateral graft failures and 21 contralateral ACL tears in the first 24 months after RTS following ACLR. At the time of RTS, 57 patients (31.5%) achieved LSI values of 90% or greater on all testing as well as an IDKC value of 90 or greater. At this level, there was no difference in ipsilateral graft failures between patients who passed all RTS criteria (15.8%) and those who failed at least 1 criterion (7.3%; p=0.08). There was also no difference in contralateral ACL injuries between patients who passed all RTS criteria (7.0%) and those who failed at least 1 criterion (13.7%; p=0.22). When individual RTS criterion were evaluated, patients who failed to achieve 90% quadriceps strength LSI were 84% less likely to suffer an ipsilateral graft failure (OR=0.16; 95%CI: 0.04, 0.74;p=0.009), but 3 times more likely to suffer a contralateral ACL injury (OR=2.5; 95%CI:1.0, 6.5;p=0.05). Conclusion: Current criteria to evaluate readiness to return young athletes to pivoting and cutting sports, may not identify young, active patients independently at high risk for a future ipsilateral graft tear or contralateral ACL injury. Inability to achieve 90% LSI on an isometric quadriceps strength assessment resulted in a reduced risk of ipsilateral graft failure, but an increased risk in contralateral ACL injury after ACLR and RTS. Further investigation is needed on the relationship between quad strength and side of future ACL injury and whether other factors may help contribute to a predictive model of future ACL injury specific to limb.

Objectives: The incidence of 2nd anterior cruciate ligament (ACL) injury after ACL reconstruction (ACLR) and return to sport (RTS) ranges from 25%-33% in young, active populations; with the greatest risk in the first 12 months after RTS. Recent data indicate that failure to successfully meet traditional RTS criteria, inclusive of strength, functional hop testing and patient reported outcome scores, may identify athletes at increased risk of future injury after ACLR. However, these studies have focused on adult populations and it is unknown if similar RTS criteria apply to young, adolescent, pivoting/cutting athletes. The purpose of this study was to determine if meeting all current, standard RTS criteria would identify young athletes at risk for future ACL injury after primary ACLR and RTS. The tested hypothesis was the likelihood of 2 nd ACL injury in the first 2 years after RTS would be lower in patients who met all RTS criteria prior to initiation of pivoting and cutting activity compared to patients who failed to meet all RTS criteria prior to RTS. Methods: One hundred fifty-nine subjects (112 female, 47 male) with a mean age of 17.2±2.6 years old (range: 13-25 y.o.) underwent ACLR and were released to return to pivoting/cutting sport. These patients were enrolled in a prospective, observational cohort study, completed a RTS assessment and were then tracked for occurrence of 2 nd ACL after ACLR for 24 months. The RTS assessment included 6 tests: isometric quadriceps strength, 4 functional hop tests and the International Knee Documentation Committee (IKDC) patient reported outcome survey. Limb symmetry index (LSI) was calculated for strength and hop test assessments [(involved/uninvolved)*100]. The IKDC was reported on a 0-100 scale with 100 representing a perfect score. Subjects were classified into groups that successfully passed all 6 RTS tests at a level of 90 and again at 95 compared to those that failed to meet all 6 criteria. Chi Square tests were used to determine if successfully passing all 6 RTS measures at various levels of symmetry resulted in a reduced risk of 2 nd ACL injury in the first 24 months after RTS. Results: Thirty-five (22.0%) patients suffered a 2 nd ACL injury, with 26 occurring in the first 12 months after RTS. At the time of RTS, 42 patients (26%) achieved LSI values of 90 or greater on all testing as well as an IKDC value of 90 or greater. The remaining 117 subjects (74%) scored below 90 on at least 1 of the 6 assessments. At this level, there was no difference in 2 nd ACL injury prevalence between patients who passed all RTS criteria (12/42; 28.6%) and those who failed at least 1 criteria (23/117; 19.7%) (p=0.23). When the passing criteria was elevated to 95 on all RTS testing, only 15 subjects (9%) successfully passed all 6 tests. There was no significant difference in 2 nd ACL injury prevalence between patients who passed all RTS criteria (5/15; 33%) and those who failed at least 1 test (30/144; 20.8%) (p=0.32). Sub-group analysis which evaluated the group by graft type, also indicated no significant differences between groups (p>0.05). Conclusion: Current criteria to evaluate readiness to return young athletes to pivoting and cutting sports, using quadriceps strength symmetry, functional hop performance symmetry and patient reported outcomes, may not identify young, active patients at high risk for 2 nd ACL injury. Future work must identify more appropriate criteria to assess readiness to RTS in the young, athletic population and incorporate these findings into practice.