Relationship Between Patient-Reported Outcomes And Strength Measures In Adolescents After Anterior Cruciate Ligament Reconstruction

Strength is a common clinical measure used to guide return to sport progression following anterior cruciate ligament reconstruction (ACLR). Automated systems have emerged in clinical settings to reduce measure error and evaluation time, but it is unknown how they compare to handheld measurement techniques or patient-reported outcome measures (PROMs). PURPOSE: Determine the relationship between traditional handheld and automated system strength measures and their relationships to PROMs in adolescents post-ACLR. METHODS: We cross-sectionally examined 30 adolescents who underwent ACLR (age: 15.0 ± 2.1 yrs; 43% male; BMI: 20.6 ± 0.1; autografts: 37% hamstring, 33% patellar, 17% quadriceps; 6.1 ± 0.4 months post-ACLR). Participants completed traditional isometric strength assessments using handheld dynamometry (hip: abduction, adduction; knee: extension, flexion) via a 2-trial average. Participants then completed the same strength measure methods using an automated dynamometer system (ForceFrame). PROMs were assessed using the Knee Osteoarthritis Outcome Score (KOOS), the International Knee Documentation Committee (IKDC), and the ACL Return to Sport Index (ACL-RSI). Pearson correlation (r) compared handheld versus automated strength measures, and Spearman’s rho (ρ) assessed the relationships of the results of each system to PROMs. Differences in ρ (ρΔ) between automated versus handheld strength measures were calculated. RESULTS: Handheld and automated strength significantly correlated for hip abduction (r = 0.56) and adduction (r = 0.69), and knee extension (r = 0.58) and flexion (r = 0.80). Handheld strength had varying relationships to the KOOS (ρ range: -0.21, 0.39), IKDC (ρ range: -0.06, 0.14), and ACL-RSI (ρ range: -0.29, -0.03). Automated measures displayed overall weaker relationships to PROMs versus handheld for KOOS (ρΔ range: -0.27, 0.25), IKDC (ρΔ range: -0.19, 0.12), and ACL-RSI (ρΔ range: -0.13, 0.08). CONCLUSIONS: Handheld and automated methods only moderately correlated to strength, indicating inadequate interchangeability between methods. Both techniques had weak correlations with PROMs, underscoring the importance of a multifactorial approach for return to sport assessments post-ACLR. Supported by: Funded by VALD Performance