A 12-week neuromuscular electric stimulation (NMES) home exercise program was shown to decrease pain and stiffness and improve functional capacity and strength in patients with knee osteoarthritis (OA), according to study findings published in Arthroplasty Today.
Quadriceps strengthening improves joint stability and decreases compressive loads on joint cartilage, delaying rapid OA progression. Portable NMES units connected to mobile apps transmit electrical impulses through adhesive electrodes on the skin’s surface at specified intensities and amplitudes, causing the muscles to contract involuntarily, recruiting more muscle fibers than voluntary exercises alone. Combining NMES with voluntary exercises is known to dramatically improve strengthening results.
Researchers at Sinai Hospital in Baltimore conducted a multicenter, randomized, sham-controlled, double-blind trial between October 2019 and June 2020, assessing the efficacy of NMES in treating knee OA symptoms.
A total of 156 patients with knee OA were randomly assigned to 2 groups — the NMES treatment group (n=106) and the sham low-voltage NMES group (n=50). By the end of the trial, 12 patients withdrew from the treatment group and 4 from the sham group.
A total of 45 patients in the NMES treatment group completed the study that included at least800 minutes of therapy during the 12 weeks.
Patient-reported outcome measures included the visual analog scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Knee Injury and Osteoarthritis Outcome Score Joint Replacement (KOOS JR), and Patient Global Impression of Change, collected at baseline and weeks 4, 8, and 12. Researchers measured isometric quadriceps strength using a handheld dynamometer.
Knee pain decreased in 64% of the NMES group compared with 42% of the sham group (P =.029). The NMES treatment group exceeded the 30% minimal clinically important difference (MCID) for pain reduction on both the VAS Nominated Activity (-42.8% vs -38.6%; P =.562) and WOMAC pain subscales (-36.8% vs -26.6%; P =.038).
According to the WOMAC stiffness subscale, knee stiffness decreased in the NMES group compared with the sham group (-44.7% vs -17.4%; P =.002), with 62% of the treatment group reporting improved joint mobility compared with the 56% of the sham group (P =.011).
Patients in the NMES group reported improvements in functional capacity compared with those in the sham group, both on the WOMAC (-40.1% vs -24.5%; P =.029) and KOOS JR functional subscales (-39.3% vs -19.7%; P =.029).
Isometric quadriceps strength increased in the fully compliant NMES subgroup compared with the entire NMES treatment group (81.5% vs 64.6%), though strength in both groups reached statistical significance (P =.0006 and P =.0001, respectively). Patients in the NMES treatment vs sham group reported more positive changes in health status (64.4% vs 44%, P =.046).
Study limitations included the potential placebo effect in the sham group, the fact that the sham group received a modified treatment version of NMES resulting in moderate improvements, and interruption of the trial proceedings due to the COVID-19 pandemic, necessitating data collection over the phone at weeks 8 and 12.
“Home-based NMES therapy…has the potential to provide suffering patients with a bridge between conservative management and definitive total knee procedures,” the researchers noted.
Disclosure: Several study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Sax OC, Gesheff MG, Mahajan A, et al. A novel mobile app-based neuromuscular electrical stimulation therapy for improvement of knee pain, stiffness, and function in knee osteoarthritis: a randomized trial. Arthroplast Today. 2022;15:125-131. doi:10.1016/j.artd.2022.03.007