Mismatch Between Physical and Psychological Outcomes at Return to Sport After ACL Reconstruction and the Association With Second ACL Injury Risk: A Cohort Study

BACKGROUND: The purpose of this study was to investigate whether a mismatch between physical function and psychological outcomes at return to preinjury level of sport (RTS) after anterior cruciate ligament (ACL) reconstruction is associated with the risk of a second ACL injury. HYPOTHESIS: A mismatch between physical function and psychological outcomes at RTS increases second ACL injury riskStudy Design:Prospective cohort (registry). LEVEL OF EVIDENCE: Level 3. METHODS: Patients registered in a local rehabilitation specific registry with ACL reconstruction, aged 15 to 40 years, who reported a preinjury Tegner level ≥6, and completed muscle function tests and patient reported outcome measures (PROs) at RTS were included. Patients were categorized into 4 our groups: (1) high physical function and high PROs (High-High), (2) low physical function and low PROs (Low-Low), (3) high physical function and low PROs (High-Low), and (4) low physical function and high PROs (Low-High). Cox regression analysis and Kaplan-Meier survival estimates were used to assess the association between group classification and second ACL injury risk within 1 year of RTS. RESULTS: A cohort of 380 patients from was included. Within 1 year of RTS, 34 (8.9%) patients sustained a second ACL injury. The second ACL injury rate was highest in the Low-High group (19.2%). However, no statistically significant difference in hazard ratios for second ACL injury was observed. CONCLUSION: A "mismatch" that consists of high muscle function and low psychological status, or low muscle function and high psychological status does not appear to affect the occurrence of second ACL injury after ACL reconstruction. CLINICAL RELEVANCE: Clinicians should be cautious not to rely solely on results from muscle function tests and PROs to clear patients for unrestricted sports participation.