Perceived Knee Joint Function And Limb Symmetry After ACL Reconstruction; Differences Between Sex And Age

Psychological readiness, patient reported function and objective quadriceps muscle strength are critical metrics to guide optimal timing of return to physical activity after ACL reconstruction (ACLR). However, age and sex based differences among these metrics warrants more precise characterization to enable patient-centered approach to healthcare decision making. PURPOSE: To determine associations between kinesiophobia, subjective and objective knee function between age and sex. METHODS: 45 patients (26F) with ACLR (29 ± 10 y; 9 ± 2 m post ACLR) completed bilateral knee extensor strength testing (isometric at 90 deg, isokinetic at 60 deg/s and 120 deg/s) and kinesiophobia (TSK-11) and perceived knee function (IKDC) surveys. Patients were divided by age (>25 y; 36 ± 7, ≤25 y; 19 ± 3) and sex (m, f). Correlation analyses were used to determine the relationship between TSK-11 and IKDC with knee extension torque limb symmetry index (LSI). RESULTS: There was a significant correlation between TSK-11 and isometric LSI in both the younger (r = -.56, p = .01) and older (r = -.50 p = .01) groups. There was no correlation between TSK-11 and isokinetic LSI at 60°/s (r = .37, p = .12) or 120°/s (r = .14, p = .56) in the younger group. Older patients had a correlation between TSK-11 and isokinetic LSI at 60°/s (r = -.48, p = .01), but not at 120°/s (r = -.32, p = .12). IKDC scores did not correlate with any outcome in the younger group, while in the older group IKDC correlated with all LSI measures; isometric LSI at 90° (ρ = .55, p < .01), isokinetic LSI at 60°/s (ρ = .59, p < .01) and 120°/s (ρ = .50, p = .01). With regards to sex, there were no significant correlations between TSK-11 or IKDC and LSI in males, while there was a correlation between TSK-11 and isometric LSI in females (r = -.51, p = .02), but not with isokinetic LSI measures. CONCLUSION: Perceived knee function did not correlate with knee extensor strength symmetry in the younger group. Kinesiophobia was more likely to relate to physical function than perceived knee function, especially in patients over 25. Personalized approach to post ACLR patient management should consider age and sex when assessing relationships between important subjective and objective metrics that are used to make decisions about return to unrestricted activity.