Selective Electrical Muscle Stimulation of the Vastus Medialis in a Patient With Knee Osteoarthritis, With Changes in Muscle Quality, Symptoms, and Physical Activity: A Case Report.
Tanino Y, Fukumoto Y, Kono T, Yoshida T • The American journal of case reports • 2026
During the observation period, vastus medialis echo intensity decreased, Knee Injury and Osteoarthritis Outcome Score scores improved, and the patient resumed aquatic walking, but because this was a single uncontrolled case and physical activity resumed during the intervention, these changes cannot be attributed to electrical stimulation alone.
Key Findings
Results
Vastus medialis echo intensity, an indirect indicator of intramuscular fat, decreased after 4 weeks of electrical muscle stimulation in a 77-year-old man with knee osteoarthritis.
Echo intensity decreased by 13.7 arbitrary units, a 25.3% reduction compared with the pre-intervention value.
Stimulation was applied to the vastus medialis for 30 minutes per session, 3 times per week, for 4 weeks.
The patient had Kellgren-Lawrence grade 2 right knee osteoarthritis, hypertension, and hyperlipidemia.
Echo intensity was measured by ultrasound before and after the intervention.
Results
Self-reported knee symptoms improved over the observation period.
The Knee Injury and Osteoarthritis Outcome Score (KOOS) was assessed before and after the intervention.
The abstract reports that knee symptoms improved during the observation period.
Results
The patient resumed aquatic walking 2 weeks after electrical stimulation was initiated.
He had previously maintained regular exercise, including aquatic walking, to manage hypertension and hyperlipidemia, but stopped because of knee pain.
Resumption of activity occurred during the intervention period.
Conclusions
The observed changes cannot be attributed to electrical stimulation alone because of the single-case, uncontrolled design and concurrent resumption of physical activity.
The authors state that spontaneous improvement, behavioral reactivation, or a combination of these factors remain plausible.
The report is a single uncontrolled case.
The authors call for controlled studies across different levels of disease severity.
Background
The case was motivated by the hypothesis that selective stimulation of the vastus medialis might reduce intramuscular fat and improve symptoms.
Fat accumulation in the vastus medialis has been associated with progression of knee osteoarthritis.
Electrical muscle stimulation may reduce intramuscular fat by inducing contractions of the targeted muscle.
What This Means
This case report describes one 77-year-old man with mild knee osteoarthritis (Kellgren-Lawrence grade 2) who stopped his usual exercise, including aquatic walking, because of knee pain. He received electrical stimulation of the inner thigh muscle (vastus medialis) for 30 minutes, three times a week, for four weeks. Ultrasound was used to estimate fat within the muscle, and a questionnaire (KOOS) measured knee symptoms.
After four weeks, the ultrasound measure of fat within the muscle (echo intensity) had dropped by 13.7 units, or about 25%, his knee symptom scores improved, and he went back to aquatic walking two weeks after starting the stimulation. This research suggests that electrical stimulation of this muscle might be worth studying further as a way to improve muscle quality and symptoms in knee osteoarthritis.
However, this was one person with no comparison group, and he also resumed exercise during the treatment. The authors state that the improvements cannot be attributed to the stimulation alone; natural improvement or the return to activity could also explain the changes. Controlled studies in people with different severities of knee osteoarthritis are needed before any conclusions can be drawn.
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Tanino Y, Fukumoto Y, Kono T, Yoshida T. (2026). Selective Electrical Muscle Stimulation of the Vastus Medialis in a Patient With Knee Osteoarthritis, With Changes in Muscle Quality, Symptoms, and Physical Activity: A Case Report.. The American journal of case reports. https://doi.org/10.12659/AJCR.954436