Background: Post-traumatic knee osteoarthritis (PTOA) is a leading cause of medical separation from military service. Anterior cruciate ligament (ACL) injury and surgical reconstruction (ACLR) incurs a high PTOA risk. Aberrant gait biomechanics contribute to PTOA development and are attributable to quadriceps muscle dysfunction. Additionally, up to 30% of patients experience secondary ACL injury. Aberrant landing biomechanics contribute to secondary ACL injury risk and are influenced by quadriceps dysfunction. Vibration acutely improves quadriceps function and gait biomechanics in individuals with ACLR, but its effects on joint health, PTOA risk, and landing biomechanics are unknown.
Hypothesis/Objective: This study will evaluate the effects of vibration embedded in ACLR rehabilitation on quadriceps function, gait biomechanics, landing biomechanics, patient self-report outcomes, return-to-physical-activity (RTPA) criteria, and MRI indicators of knee joint health. The central hypothesis is that vibration will enhance gait and landing biomechanics consistent with reduced PTOA and secondary ACL injury risks, respectively, and that whole body vibration (WBV) delivered by a commercial device and local muscle vibration (LMV) delivered by a prototype device will produce equivalent improvements in the study outcomes. The rationale for the hypothesis is that vibration will more effectively improve quadriceps function compared to standard rehabilitation, thus restoring normal biomechanics and mitigating declines in joint health.
Specific Aim 1: To compare the effects of Standard rehabilitation vs. Vibration rehabilitation (WBV and LMV) on quadriceps function. The investigators hypothesize that Vibration will produce superior outcomes (e.g. strength) compared to Standard rehabilitation, but that WBV and LMV will produce similar outcomes.
Specific Aim 2: To compare the effects of Standard rehabilitation vs. Vibration rehabilitation on gait biomechanics linked to PTOA development. The investigators hypothesize that Vibration will produce superior outcomes compared to Standard rehabilitation, but that WBV and LMV will produce similar outcomes.
Specific Aim 3: To compare the effects of Standard rehabilitation vs. Vibration rehabilitation on patient self-report outcomes. The investigators hypothesize that Vibration will produce superior outcomes compared to Standard rehabilitation, but that WBV and LMV will produce similar outcomes.
Specific Aim 4: To compare the effects of Standard rehabilitation vs. Vibration rehabilitation on MRI indicators of knee joint health. The investigators hypothesize that cartilage composition (e.g. collagen, water, and proteoglycan content) will be poorer and PTOA incidence (MOAKS score) will be higher in the Standard cohort compared to both Vibration cohorts, but that WBV and LMV will produce similar outcomes.
Specific Aim 5: To compare the effects of Standard rehabilitation vs. Vibration rehabilitation on landing biomechanics linked to secondary ACL injury risk. The investigators hypothesize that Vibration will produce superior outcomes compared to Standard rehabilitation, but that WBV and LMV will produce similar outcomes.
Specific Aim 6: To compare the effects of Standard rehabilitation vs. Vibration rehabilitation on the probability of meeting evidence-based RTPA criteria (e.g. single-leg hop symmetry ≥90%). The investigators hypothesize that Vibration will display result in greater probabilities of meeting RTPA criteria compared to Standard rehabilitation at 6 months and 1 year post-ACLR, but that WBV and LMV will produce similar outcomes.
Specific Aim 7: To evaluate changes in quadriceps muscle quality over the first year following ACLR reconstruction surgery. The investigators hypothesize that quadriceps muscle quality will decline at 1, 6 and 12 months post-ACLR compared to preoperative measurements and that these changes will be more pronounced in the ACLR limb compared to the uninjured limb at 1, 6 and 12 months post-ACLR.
Specific Aim 8: To evaluate associations between changes in quadriceps muscle quality over the first year following ACLR. The investigators hypothesize that declines in muscle quality between preoperative and 1- and 6- months post-ACLR timepoints will be associated with lesser knee extensor strength, aberrant gait biomechanics, worse patient self-report and functional outcomes, and deleterious alterations in knee cartilage composition.
Specific Aim 9: To compare the effects of Standard rehabilitation vs. Vibration rehabilitation on quadriceps muscle quality. The investigators hypothesize that Vibration will produce superior outcomes compared to Standard rehabilitation, but that WBV and LMV will produce similar outcomes.
Study Design: The approach will be to recruit ACLR patients at the onset of rehabilitation and conduct a Phase II single-blind randomized controlled trial to compare the effects of standard ACLR rehabilitation (control) vs. standard rehabilitation that incorporates WBV or LMV on the study outcomes over the first year post-ACLR.
Impact: This study will evaluate the effects of a novel rehabilitation approach on factors related to the risks of PTOA and secondary ACL injury following ACLR. ACL injury risk is 10x greater in military personnel vs. civilians, and PTOA is a leading cause of medical separation from military service, degrades quality of life, increases the risks of several comorbidities (e.g. obesity), and is a primary contributor to years of life lost due to disability. Improving rehabilitation of knee injuries is paramount for maintaining the combat readiness of the armed forces and preserving the health and well-being of Service members and Veterans, as well as millions of Americans at risk of PTOA. Vibration represents a promising approach to this important challenge. Furthermore, in addition to being cost-effective, the portable nature of the prototype LMV device could have substantial implications for military personnel and US citizens, particularly those with limited access to rehabilitation facilities.
