PURPOSE: Although basic objective measures (e.g. knee laxity, strength, hop tests) have been related to subjective measures of function, associations between knee-specific objective and subjective measures have yet to be completed. The objective was to determine if knee joint contact and ligament forces differ between pre and post-ACL reconstructed states and if these forces relate to their patient's respective subjective functional ability scores.

METHODS: Twelve patients performed a hopping task pre and post-reconstruction. Magnetic resonance images and OpenSim were used to develop patient-specific models in static optimization and joint reaction analyses. Questionnaires concerning each patient's subjective functional ability were also collected and correlated to knee joint contact and ligament forces.

RESULTS: No significant differences were observed between deficient and reconstructed groups with respect to knee joint contact or ligament forces. Nevertheless, there were several significant (p < 0.05) moderate to strong correlations between subjective and objective measures including Tegner activity level to contact force in both states (r = 0.67 - 0.76) and IKDC (International Knee Documentation Committee) to compressive and anterior shear forces (r = 0.64 - 0.66).

CONCLUSION: Knee-specific objective measures of a patient's functional capacity can represent their subjective ability, which explains this relationship to a greater extent than past anatomical and gross objective measures of function. This consolidation is imperative for improving the current rehabilitation schema as it allows for external validation of objective and subjective functional measures. With poor validation of subjective function against objective measures of function, the re-injury rate is unlikely to diminish, continuing the heavy financial burden on healthcare systems.Key Terms: Knee, Musculoskeletal modelling, Rehabilitation, patient-specific.