Jenny Hledik, PhD;
Thomas P. Andriacchi, PhD
Chronic knee pain affects one in four adults1 and is a leading reason patients seek chiropractic care.2 As the population ages, osteoarthritis and knee injury-related conditions increasingly limit mobility, impair proprioception and reduce quality of life.
While medication, bracing and manual therapies can play important roles in treatment, there is growing interest in non-invasive, self-administered approaches patients can use at home. Intermittent cutaneous vibration, activated and deactivated by the user’s knee movement during activity, offers a drug-free method to interrupt pain signals and enhance quadriceps muscle function between chiropractic clinic visits.
The Science: Pain Relief
Intermittent vibration activated by movement draws on the gate control theory of pain, which holds that nonpainful input can reduce transmission of nociceptive signals to the brain.3
When intermittent cutaneous vibration is applied to the knee area during movement, large-diameter somatosensory nerve fibers are activated and transmit the vibratory stimulus more rapidly than small-diameter pain fibers, inhibiting transmission of the smaller nerve fiber activity to the brain. This creates a “gating” effect, reducing pain perception during dynamic activity. (Figure 1)
Because the vibratory stimulus is intermittent, triggered just before heel strike and turning off at mid-stance of each step, the vibration activates during the loading phases of walking and stair navigation, when patients need it most. This intermittent vibratory stimulus ensures the nervous system remains responsive, avoiding habituation that can occur with continuous stimulation.
The Science: Enhancing Quadriceps Muscle Function
In addition to pain relief, intermittent motion-activated cutaneous vibration has been shown to enhance quadriceps muscle function.4-6 The quadriceps muscles play a key role in joint stabilization during movement and help protect against excessive forces that can damage ligaments, cartilage and other joint structures.
In people with knee pain, especially from conditions like osteoarthritis, or after ACL or meniscal injury, quadriceps dysfunction is common. Unfortunately, this can result in a vicious cycle whereby knee conditions and knee pain lead to reduced quadriceps function, which can compromise joint loading,7 proprioception and stability; and over time, contribute to greater joint degeneration, disability and increased pain.8
Clinical Evidence Supporting Efficacy
The use of intermittent motion-activated cutaneous vibration in knee pain populations has been studied in clinical research,4-6 validating the therapeutic potential of this approach. In individuals with knee pain due to osteoarthritis, ACL tear or meniscal tear, significant improvements in quadriceps muscle function were observed during walking both in a single testing session4 and after longer-term (four weeks) use.5
The intermittent vibration was applied via two motion-sensing bands placed above and below the knee, which used an algorithm to process motion data in real time to initiate vibration just prior to heel strike and turn off vibration at midstance.
In a longitudinal, randomized, controlled crossover study, adults with knee pain due to osteoarthritis or prior injury were assigned to wear active (motion-activated intermittent vibration) or control (passive compression only) knee bands for four weeks each, with a two-week washout period in between treatments.
Cutaneous vibration activated by knee movement during activity significantly reduced pain during both walking and stair navigation,5-6 which was not observed with the passive knee treatment. The change in pain after four weeks of cutaneous intermittent vibration suggests intermittent vibration provided the necessary added stimulus to improve patients’ symptoms as compared to the nominal pressure produced by compression-only bands.
Following four weeks of use, the motion-activated vibration was also shown to significantly improve quadriceps function during walking and stair ascent, as well as enhance proprioceptive control during stair descent.5-6
Integrating Into Chiropractic Practice
Chiropractors can readily incorporate motion-activated intermittent cutaneous vibration into comprehensive treatment plans. Several factors can help to optimize success:
Patient Selection: Ideal candidates include those with chronic knee pain who remain ambulatory and motivated to maintain activity levels. The therapy is particularly beneficial for patients with osteoarthritis, prior injuries like ACL tears or meniscal tears, or sports-related injuries.
Education and Compliance: Patient understanding of the therapy’s mechanism enhances adherence. Explaining how motion-activated vibration works and emphasizing its role in supporting overall treatment goals can improve outcomes.
Device Features: Effective devices should provide intermittent, rather than continuous stimulation, be motion-activated, and demonstrate clinical validation through peer-reviewed research.
Integration Timeline: The therapy can be introduced early in treatment to help patients engage more comfortably in rehabilitative exercises and daily activities.
Because intermittent cutaneous vibration is patient-activated, it reinforces positive movement habits and empowers individuals to manage symptoms between visits.
Clinical Relevance: Addressing Multiple Pathophysiological Factors
Chronic knee pain typically involves several interconnected issues that this therapy addresses simultaneously:
Pain Modulation: The vibration stimulation provides analgesic effects through sensory gating mechanisms, allowing patients to move with greater comfort.
Muscle Function Enhancement: By reducing pain during movement, the therapy helps restore normal quadriceps activation patterns that are often inhibited in knee pain conditions. This is crucial since quadriceps weakness contributes to joint instability and functional decline.
Proprioceptive Restoration: Clinical studies demonstrate that motion-activated vibration enhances proprioceptive feedback during movement, particularly important for patients whose joint position sense has been compromised by pain, inflammation or injury.
Activity Encouragement: Unlike passive treatments, this approach requires patient movement to activate, inherently promoting the physical activity essential for joint health and overall wellness.
Practical Takeaway
As osteoarthritis and chronic knee pain rise, conservative practitioners must adopt innovative, evidence-based tools patients can use beyond the clinic. Motion-activated intermittent cutaneous vibration interrupts pain transmission, enhances key muscle function and bolsters proprioception in real-world activities.
Simple to integrate and backed by peer-reviewed research, this modality aligns with chiropractic principles of natural, patient-centered care. Incorporating this adjunct into treatment plans can help chiropractors expand their therapeutic repertoire, improve outcomes and empower patients to stay active with less pain.
References
- Bunt CW, Jonas CE, Chang JG. Knee pain in adults and adolescents: the initial evaluation. Am Fam Physician, 2018 Nov 1;98(9):576-585.
- de Luca K, et al. The profile of older adults seeking chiropractic care: a secondary analysis. BMC Geriatr, 2021;21(1):271.
- Melzack R, Wall PD. Pain mechanisms: a new theory. Science, 1965;150(3699):971-979.
- Fischer AG, et al. Activating the somatosensory system enhances net quadriceps moment during gait. J Biomech, 2019;82:149-155.
- Fischer AG, et al. Utilizing the somatosensory system via vibratory stimulation to mitigate knee pain during walking: randomized clinical trial. Gait Posture, 2020;80:37-43.
- Fischer AG, et al. Intermittent vibrational stimulation enhances mobility during stair navigation in patients with knee pain. Gait Posture, 2021;86:125-131.
- Hortobágyi T et al. Aberrations in the control of quadriceps muscle force in patients with knee osteoarthritis. Arthritis Rheum, 2004 Aug 15;51(4):562-9.
- Segal NA, Glass NA. Is quadriceps muscle weakness a risk factor for incident or progressive knee osteoarthritis? Phys Sportsmed, 2011 Nov;39(4):44-50.
