Active Voice: Gait Biomechanics in ACL Reconstructed Knees at Different Time Frames Post-Surgery

By John Goetschius, Ph.D., A.T., ATC, and Joseph M. Hart, Ph.D., ATC, FACSM, FNATA

John Goetschius, Ph.D., A.T., ATC Joseph M. Hart, Ph.D., ATC, FACSM, FNATA
Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily represent positions or policies of ACSM.

John Goetschius, Ph.D., A.T., ATC, is an assistant professor of exercise science & athletic training at Adrian College in Adrian, Michigan. He earned his Ph.D. from the University of Virginia under the advisement of Dr. Joseph M. Hart. His research interests include improving clinical outcomes for patients with a history of lower-extremity joint injury through the study of post-traumatic muscle dysfunction and clinical interventions. He is a licensed athletic trainer and an ACSM member.

Joseph M. Hart, Ph.D., ATC, FACSM, FNATA, is an associate professor of kinesiology in the Curry School of Education at the University of Virginia in Charlottesville, Virginia, where he serves as co-director of the Exercise & Sport Injury Laboratory. He also serves in the Department of Orthopaedic Surgery as the director of clinical research. Dr. Hart’s research interests relate to outcomes of ACL reconstruction, including rehabilitation interventions, assessment of muscle strength and biomechanics, return to physical activity and post-traumatic osteoarthritis.

This commentary presents Dr. Goetschius’ and Dr. Hart’s views on the topic of a research article that they had published with other colleagues. Their paper appears in the November 2018 issue of
Medicine & Science in Sports & Exercise® (MSSE).

Approximately 50 percent of patients with a history of ACL reconstruction (ACLR) surgery will develop knee osteoarthritis (OA) within the first two decades after surgery. This statistic is particularly concerning when we consider that the majority of ACLR surgeries are performed on young, physically active adolescents.

Despite rehabilitation and return to activity, many ACLR patients continue to exhibit muscle weakness and altered biomechanics during everyday activities. During gait, ACLR patients have demonstrated abnormal sagittal and frontal plane knee joint loading patterns. Over time and repetition, these patterns could facilitate degenerative stresses of the articular tissues of the knee and an accelerated progression of knee OA. Conventional theory suggests that, due to insufficient post-surgical rehabilitation, patients will continue to exhibit persistent abnormal joint loading during walking and running. However, our true understanding is limited with respect to how lower extremity biomechanics present over time after ACLR. An improved understanding of how patients are moving during the years after release from clinical care could provide valuable insight. More specifically, knowledge of the relationship between lower extremity biomechanics and knee OA progression could help identify new potential opportunities for clinical intervention.

Thus, as presented in our paper published in the November 2018 issue of MSSE, we examined lower-extremity joint loading and movement patterns during gait in ACLR participants. The subjects were stratified into groups based on time post-surgery: nine to 24 months (n=18), two to five years (n=20), and more than five years (n=18). We recruited young adults with a history of ACLR on one leg and a group of healthy controls with no lower-extremity injury history (n=18). We used 3D motion analysis with an instrumented treadmill to measure knee and hip kinetics and kinematics during walking and jogging at standardized speeds. Between limb and between groups comparisons were performed.

Aligning with conventional theory, the ACLR group at nine to 24 months post-surgery demonstrated reduced sagittal and frontal plane joint loading on their ACLR limb, which may be the product of movement strategies to protect the joint early after surgery. However, contrary to conventional theory, the ACLR group at two to five years post-surgery demonstrated “normal” joint loading patterns like those observed in the healthy controls. Additionally, the ACLR group at more than five years post-surgery demonstrated elevated frontal plane and reduced sagittal plane joint loading ? loading patterns that have been associated with knee OA.

Collectively, these findings suggested that lower-extremity biomechanics may recover within two to five years post-surgery, but that deterioration toward more risky joint loading patterns may present in the later years post-surgery. These findings were obtained from a cross-sectional analysis, as opposed to those from serial evaluations of the same subjects; furthermore, knee OA was not measured in our study. Yet, our data suggests movement deterioration with time. This result is concerning and raises the prospect of compromised knee health in the long term after ACLR. The traditional model of ACLR clinical care emphasizes early rehabilitation during the first four to 12 months post-surgery. Perhaps ACLR patients could benefit from care plans incorporating serial follow-ups to track and treat progressive changes in muscle function and biomechanics that may develop during the later years following ACLR. Our findings support the need for longitudinal study of lower-extremity biomechanics over the first decade after ACLR.
different changes to the nervous system.

It would be relevant to understand whether these differences are maintained if the HIIT and MICT protocols were matched in terms of total work or energy expenditure, as differences in total training volume and average intensity might bias results favoring one training over the other (e.g., larger adaptations for high-threshold motor units after HIIT). Therefore, further research in this area is warranted.