Vibration Therapy: Shaking Off Knee Pain

Written by Gabriel Ettenson, MS, PT

In the average Physiotherapy clinic, knee pain ranks second among the never ending list of diagnoses requiring intervention. Whether it is osteoarthritis, torn cartilage (often referred to as a meniscus tear), patellofemoral pain (pain under the knee cap), a ligament sprain, or tendonitis, these conditions can all lead to severe functional limitation and a reduction in one’s quality of life. In the past, most of these conditions were treated with injections, medication, and ultimately, surgery. Over time however, we have come to realize that through appropriate, individualized, conservative management; part of which should, without doubt, include vibration therapy, there is potential to fully recover “without the need to cut”.

Anatomy of the Knee

The knee joint itself, a pivotal hinge joint, is capable of bending and straightening (flexing and extending) as well as rotating inward and outward (internally and externally rotating).  It is comprised of two articulations; one between the femur and the tibia (tibiofemoral joint) and one between the femur/tibia complex and the kneecap (the patellofemoral joint).  Supporting the inside and outside of the joint, and primarily responsible for its strength and stability, are multiple ligaments and several groups of muscles; among which are the quadriceps, hamstrings, hip adductors, hip abductors, and the muscles of the calf. Over time, the relatively simple design of the knee joint coupled with its “undesirable” anatomical location make it highly susceptible to harmful shearing forces, deleterious compressive forces, abnormal patellar tracking created by muscular imbalances, and biomechanical movement dysfunctions leading to overuse injuries and painful trauma to the surrounding connective tissue (tendons, ligaments, muscles and fascia).

The Influence of Vibration on Knee Pathology

We have already established that vibration therapy / training can successfully improve circulation, lymphatic mobility, muscle tone and strength, muscle flexibility, joint proprioception, and most importantly, efficiency of the neuromuscular system. When treating an individual with knee pathology, it is by carefully and selectively harnessing these systemic effects that successful treatment can be accomplished and the long term benefits maintained.
Osteoarthritis (OA): A common degenerative condition, knee OA generally refers to the progressive, degenerative changes to the articular cartilage that lines the surfaces of the bones that comprise the knee joint.  It may or may not include wearing of the under surface of the patella (knee cap) as well. In either case, once the cartilage has deteriorated, the bony surfaces are exposed and with repeated exposure to normal, unavoidable, compressive forces (i.e. walking, standing, stairclimbing, exercise etc.), pain and inflammation will ensue. The end result of these painful changes is a gradual reduction in joint mobility, reduced viscosity of the joint, decreased local muscular activity and support, local connective tissue tightness (including muscle tissue), gait dysfunction, and a reduced overall functional level.
For the individual that suffers from OA, “traditional” therapy interventions, although successful at times, have limitations. Chief amongst these limitations is the inability to consistently tolerate weight bearing exercises (squats, lunges, step activities etc.); an integral part of the recovery process and essential for restoring the support and shock absorbing capabilities of the muscles around the joint. With vibration therapy, when first considering the squat position, a cornerstone exercise for lower body strength, the design of the platform allows the patient to utilize the upper body to control the amount of weight through the lower body. This helps them maintain their weight comfortably through their heels while successfully holding the appropriate joint angle. Successfully holding this position through a 30-60 second interval will not only “jumpstart” the neuromuscular system, but immediately improve circulation to the joint as well as local muscular activity and tone. This will allow the patient to tolerate further weight bearing exercises; exercises that may include the wide squat, superman squat, lunge, bridge, or unsupported heel raise.
We have only now just begun….outside of the benefits listed above, it is important to understand that, during the squat (as well as most other exercise performed on the platform), there are other systems at work as well. Most important among these systems is the proprioceptive system (please refer to my previous article for more detailed information on this system). When motion is lost in an arthritic joint, as is the case with OA, the proprioceptive system struggles to maintain clear and concise communication with the brain. The resulting issues lead to gait dysfunction, poor balance responses, and poor muscle fiber recruitment. Through vibration therapy, an extremely high amount of activity is placed upon the joint proprioceptors and the system as a whole. As a result there is an over-correction of sorts and this serves to improve the proprioceptive system’s efficiency overall.
Shall I keep going? How about the lymphatic system? One of this system’s responsibilities, as it applies to OA, is to help remove the excess swelling that is typically seen in an arthritic joint (acute and chronic). Often responsible for interfering with local muscle activity, this swelling also occupies space within the joint and creates further limitation in movement. Like no other form of treatment, vibration therapy, through the extremely high number of muscle contractions it creates, significantly enhances lymphatic system mobility and can lead to the quick and efficient removal of excess fluid in the joint.
At this point you are probably quite tired of reading, but I could never live with myself if I didn’t address the final, critical dysfunction seen in the individual with knee OA….reduced muscle flexibility and myofascial restriction. It has been touched upon many times in previous articles on this site, but if there is ever a jaw-dropping benefit of vibration therapy, it’s the way in which it can be utilized safely to override the normal resistance to stretch provided by the muscle spindle and its inhibitory communication with the central nervous system. By utilizing the vibration platform with proper body positioning, muscle length and myofascial mobility can be improved faster than any other flexibility based intervention available (medieval torture devices excluded of course).