Vibratory Stimuli: A Novel Rehabilitation Method for Preventing Post-Traumatic Knee Osteoarthritis

Knee osteoarthritis (OA) is a leading cause of disability that places an enormous economic burden on our healthcare system. The prevalence of OA is 1.3 to 2.2 times greater in members of the military than in the general population, and it is the leading cause of medical discharge from the military during peacetime (36%) and the second leading cause during armed conflict (31%). Knee OA also incurs other negative health implications such as increased risks for depression and cardiovascular disease, and reduced physical ability. Knee OA commonly results from traumatic knee injuries. One of the most common complications associated with knee injuries is lingering weakness/dysfunction of the quadriceps muscle on the front of the thigh. This muscle is essential for normal function because it serves as a 'shock absorber' during walking gait. Quadriceps dysfunction impedes the body's ability to absorb the forces caused by impact between the foot and the ground during walking and has been linked to development of OA. Additionally, individuals with knee injuries have sensory/proprioceptive deficits. In combination, proprioceptive deficits and quadriceps dysfunction cause changes in how injured individuals walk (gait biomechanics) that increase their risk of developing knee OA. However, current rehabilitation methods do not address the underlying causes of quadriceps dysfunction and proprioceptive deficits; thus, they are minimally effective for preventing knee OA. Anterior cruciate ligament injury and surgical reconstruction (ACLR) is an example of a knee injury that dramatically increases the risk of developing knee OA. Though surgical reconstruction is the standard of care and improves the stability of the joint, it does not decrease the risk of developing OA. However, ACLR is not specifically the focus of this investigation. ACL injury only occurs in roughly 3% of military personnel each year. However, individuals with ACLR represent a group that is at high risk for developing knee OA and an ideal population for testing novel rehabilitation techniques designed to decrease the risk of developing knee OA following knee injuries. ACLR is one of many injuries that could benefit from the findings of this investigation. Quadriceps dysfunction and proprioceptive deficits are present with meniscus injuries, patellofemoral pain syndrome, and intra-articular fractures, as well as in individuals who have already been diagnosed with knee OA; thus, individuals with these injuries would also be expected to benefit from these treatments. Knee injuries are the third most prevalent cause of battlefield evacuation and comprise 19% of all injuries sustained during military training and 15% of all non-combat injuries during deployment. Furthermore, knee injuries sustained during combat almost universally result in OA. As such, the results of this investigation have the potential to impact the health and well-being of numerous military personnel. Vibration applied to a muscle can improve its function and may also improve proprioception. There are two general types of vibration that are used for these purposes: whole body vibration (WBV) and local muscle vibration (LMV). If these vibratory stimuli improve quadriceps function and proprioception, they may also improve walking gait biomechanics by enhancing 'shock absorption,' thus reducing the risk of developing knee OA in individuals with knee injuries. We recently demonstrated that WBV and LMV produce equal improvements in quadriceps function in healthy individuals. This is a very important finding due to the fact that WBV devices are expensive (as much as $10,000) and are not portable. However, LMV devices are much less expensive (~$250) and are highly portable for use in a variety of settings, including rehabilitation clinics, military field settings, and the patient's home. Therefore, LMV may be a cost-effective alternative to WBV. The objective of this research projec