Females Meet Return to Sport Criteria at Lower Rates Than Males 9 Months After ACL Reconstruction

Recovery from anterior cruciate ligament reconstruction (ACLR), common in adolescent athletes, requires restoration of knee strength, stability, and range of motion prior to return-to-sport (RTS) clearance. RTS protocols incorporate strength and functional testing with patient-reported outcome measures (PROMs) to assess readiness. However, females report lower RTS readiness and lower RTS rates (37%) compared to males (52%) (Webster, 2018; Kostyun, 2021). Understanding sex-based differences in RTS testing is essential for optimizing rehabilitation and outcomes.

Sex based differences exist in RTS testing metrics following ACLR in adolescent athletes.

A retrospective chart review was conducted on 69 (37M, 32F) patients, aged 13-20y, who underwent primary ACL-R and RTS testing. Eighty-eight RTS tests were completed at 6 months (n=44) or 9 months (n=44) post-operatively; 19 patients tested at both time points. Exclusions included multi-ligament injuries, revision ACL, outside surgeries, and extreme outliers (> 3 SD). Patients were grouped by sex and subdivided by RTS testing interval (6- or 9-months post-op) for comparisons. Physical RTS measures included limb symmetry index (LSI) of quadriceps and hamstring strength, Y-balance composite, and single-leg hop scores. PROM consisted of the ACL-Return to Sport after Injury (ACL-RSI) scale. Passing threshold was defined as ≥90% on physical metrics and ≥80% on ACL-RSI. Fisher's exact test (α = 0.05) was used to compare the proportion of patients meeting RTS passing criteria between sexes and across time points.

Passing rates for quadriceps and hamstring strength, hop tests, and balance assessments were low at 6 months post-op but improved by 9-months in both sexes (Table 1). Males consistently demonstrated higher passing rates across all RTS metrics and timepoints (Figure 1). Overall, only 44.2% of patients passed quadriceps strength testing and 50% of patients passed the ACL-RSI at 9-month post-op. Males had significant differences passing quadriceps testing (p =.002) and ACL-RSI (p =.041) between 6 and 9-months. The proportion of males passing ACL-RSI was significantly higher (p =.031) than females 9 months post-op.

Identifying sex-based differences in RTS metrics can help specialize RTS rehabilitation and improve outcomes for adolescent athletes post-ACLR. The quadriceps strength and ACL-RSI passing rate for males is double that of females while reporting similar averages between patients who passed those metrics. Overall, nearly 50% of patients did not meet passing criteria in quadriceps strength and ACL-RSI at 9 months post-op, suggesting that this standard timepoint used for RTS criteria may be too early for many patients.