Clinical Tests Can Be Used to Screen for Second Anterior Cruciate Ligament Injury in Younger Patients Who Return to Sport

BACKGROUND: Younger athletes have high rates of second anterior cruciate ligament (ACL) injury. Return-to-sport criteria have been proposed to enable athletes to make a safe return, but they frequently lack validation. It is unclear whether commonly recorded clinical measures can help to identify high-risk athletes. PURPOSE: To explore the association between commonly recorded clinical outcome measures and second ACL injury in a young, active patient group. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Included in this study were 329 athletes (200 males, 129 females) younger than 20 years at the time of first primary ACL reconstruction surgery who had subsequently returned to sport participation. Clinical examination included range of knee motion (passive flexion and extension deficits), instrumented anterior knee laxity, and single- and triple-crossover hop for distance. Patients also completed the subjective International Knee Documentation Committee form. All measures were collected prospectively at a 12-month postoperative clinical review. Patients were evaluated for a minimum 3 years to determine the incidence of subsequent ACL injury. RESULTS: A total of 95 patients (29%) sustained a second ACL injury following clinical assessment and return to sport. There were 50 graft ruptures and 45 contralateral ACL injuries. Patients with a flexion deficit of 5° had over 2 times the odds of sustaining a graft rupture (odds ratio, 2.3; P < .05), and patients with a side-to-side difference in anterior knee laxity of 3 mm or greater had over 2 times the odds of sustaining a contralateral ACL injury (odds ratio, 2.4; P < .05). Overall, 29% (94 of 329) of patients met the threshold for satisfactory function on all 6 clinical measures; these patients had a 33% reduction in the risk of sustaining a second ACL injury (P = .05) as compared with those who did not meet all clinical thresholds. CONCLUSION: Clinical measures of knee flexion and stability may have utility to screen for and identify patients who are at greater risk for a second ACL injury in an already high-risk group (ie, age and activity level).