Inter-Relationships between Static and Dynamic Indicators of Knee Recovery versus Maintenance of Sports Participation at 5-To-10 Years after Acl Reconstruction

Introduction: Objective indicators of ongoing sports participation long after ACL reconstruction are not well established. The purpose of this study was to test inter-relationships between static and dynamic indicators of knee recovery and their association with sports participation at 5-to-10 years after ACL reconstruction.

Materials and Methods: 30 men after isolated autologous hamstrings ACL reconstruction at the age 18-35 years with 5-to-10 year follow-up that didn`t sustain re-injuries underwent static and dynamic knee evaluation. This included: KT-difference, knee extensors/flexors isokinetic test, time-to-stabilization and knee moments during single-legged vertical drop test, and single-legged hop for distance. Sports participation was quantified with Tegner/Marx activity level scales, IKDC-subjective, and KOOS-sub-scores. Inter-relationships were tested between the static and dynamic indicators of knee recovery and the success of ongoing sports participation.

Results: Lower KT-difference was associated with higher Tegner/Marx scores (r = -0.39), IKDC-subjective (r = -0.35), and KOOS-QOL (r = -0.39), (all p <0.05). Knee extensors/flexors peak torque recovered 90%, but this small deficiency was significant (p <0.01), and was associated with Tegner/Marx scores (r =0.42 to 0.47, p <0.05), IKDC-subjective and all KOOS-sub-scores (r =0.37 to 0.53, p <0.05). Time-to-stabilization symmetry was associated with lower KT-difference (r =0.37, p <0.05), but was not associated directly with any sports participation score. Knee valgus and extension moments during vertical drop test were associated with single-legged hop for distance, but not with any sports participation score. Single-legged hop for distance symmetry was associated with knee extensors peak torque symmetry (r =0.42, p <0.05), but only with KOOS-ADL among the sports participation scores (r =0.4, p <0.05).

Conclusions: Among a battery of inter-related objective measures of knee recovery, the combination of KT-difference with knee extensors/flexors torque can be used to identify athletes with high likelihood of successful ongoing sports participation at 5-to-10 years after ACL reconstruction.