Long-Term Kinematic Differences in ACLR vs ACL-Deficient Individuals During Vertical Hops

Overview

This study investigated trunk, hip, and knee kinematics during vertical hops in individuals over 20 years post-unilateral ACL injury, comparing those treated with reconstruction plus physiotherapy (ACLR), physiotherapy alone (ACLPT), and healthy controls. Results revealed distinct combined movement patterns between groups and between injured and non-injured legs, highlighting compensatory strategies especially in the ACLPT group.

Background

Anterior cruciate ligament (ACL) injuries commonly occur during sports and lead to altered knee joint mechanics, potentially causing instability and osteoarthritis. While short-term kinematic changes post-ACL injury have been studied, long-term effects remain less clear. Vertical hop (VH) tests are clinically relevant for assessing dynamic knee function and can reveal subtle movement strategy differences. Understanding combined trunk, hip, and knee kinematics decades after injury can inform rehabilitation and long-term management.

Data Highlights

The study included 32 ACLR, 34 ACLPT, and 33 control participants matched for age and sex. Participants performed barefoot vertical hops on a force plate, with kinematic data collected for trunk, hip, and knee. Radiological knee osteoarthritis was present in ~90% of ACL-injured participants but did not affect knee kinematics. The ACLR group had patellar tendon autografts and standardized post-op rehabilitation, while ACLPT participants underwent tailored physiotherapy. Kinematic analyses used multivariate methods to detect combined movement patterns.

Key Findings

• Both ACLR and ACLPT groups demonstrated altered combined kinematics of the trunk, hip, and knee during vertical hops compared to controls over 20 years post-injury.
• The ACLPT group showed more pronounced deviations, likely reflecting compensatory strategies for knee instability, including reduced active range of motion.
• Differences in movement strategies were observed between injured and non-injured legs within both ACLR and ACLPT groups, indicating persistent asymmetries.
• Despite similar hop height and limb symmetry indices, kinematic analyses revealed altered coordination patterns, emphasizing the importance of assessing combined joint movements.
• Radiological osteoarthritis did not significantly impact knee joint kinematics in this cohort.

Clinical Implications

Clinicians should consider long-term altered movement strategies in ACL-injured individuals, especially those treated without reconstruction, as these may contribute to joint instability and osteoarthritis progression. Rehabilitation programs might benefit from targeting combined trunk, hip, and knee kinematics rather than focusing solely on knee function. Assessment tools like the vertical hop test with multivariate kinematic analysis can aid in detecting subtle compensations and guide individualized interventions.

Conclusion

This study highlights persistent, distinct kinematic adaptations in trunk, hip, and knee during vertical hops more than two decades after ACL injury, particularly in those treated conservatively. Evaluating combined joint movement patterns provides valuable insight beyond traditional functional tests and may improve long-term management strategies.

References

1. Vandenberg et al. 2021 -- Importance of Hip Kinematics in ACL Injury
2. Previous cohort studies 2010-2020 -- Long-term ACL Injury Outcomes
3. Clinical guidelines on ACL rehabilitation -- 2015