Electro-acupuncture delivers in knee osteoarthritis

Intensive acupuncture, enhanced by an electric current, quells pain and helps improve physical function in patients with knee osteoarthritis (OA), as shown in a study.

The therapeutic benefits of electro-acupuncture (EA) persisted for up to 26 weeks, the investigators noted. Meanwhile, the effect of manual acupuncture (MA) on pain and function appeared later but also sustained throughout the follow‐up.

In total, 442 knee OA patients (mean age, 62.8 years; 76 percent female; mean body mass index, 25.5 kg/m²) were randomized to undergo 30-minute sessions of EA (n=151), MA (n=145), or sham acupuncture (SA; n=146) three times weekly for 8 weeks, then followed for 18 weeks post-treatment. All of them complained of knee pain for >6 months, with a pain score of >4 on the numeric rating scale (NRS; range, 0-10).

At week 8, the proportion of patients who simultaneously achieved minimal clinically important improvement in pain (NRS score) and function (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] score) was 60.3 percent with EA, 58.6 percent with MA, and 47.3 percent with SA. [Arthritis Rheumatol 2020;doi:10.1002/art.41584]

Response in the EA group was significantly better than in the SA group (difference, 13.0 percent, 97.5 percent confidence interval [CI], 0.2–25.9; p=0.0234), while there was no meaningful difference between the MA and SA groups (difference, 11.3 percent, 97.5 percent CI, –1.6 to 24.4 percent; p=0.0507).

“The response rates in the EA and MA groups were both significantly higher than the SA group at weeks 16 and 26,” the investigators noted.

Acupuncture-related adverse events, such as subcutaneous haematoma, postneedling pain, and pantalgia, occurred in 11.5 percent of patients in the EA group, 14.2 percent in the MA group, and 10.8 percent in the SA group. All events were mild and resolved spontaneously in the subsequent week.

According to the investigators, the effect size of EA for knee OA was similar to topical nonsteroidal anti-inflammatory drugs (ie, diclofenac or ketoprofen) for pain relief in chronic musculoskeletal pain (60 percent) and to acupuncture for joint pain from aromatase inhibitors in women with early stage breast cancer (58 percent) in previous trials. [Cochrane Database Syst Rev 2016;4:CD007400; JAMA 2018;320:167-176]

“EA provides continuous electrical stimulation and may provide additional dosage of acupuncture. Not surprisingly, a network meta-analysis suggested that EA might be one of the best choices in all acupuncture types for knee OA,” they said. [Evid Based Complement Alternat Med 2018;2018:1638904]

“Moreover, a recent trial indicated that strong-electricity EA was better than weak-electricity EA in alleviating knee pain. In [the current] trial, however, we managed the electric stimulation as imperceptible as possible in the EA group for the purpose of blinding, which may account for the actual response rate [being] less than the expected 70 percent,” they pointed out. [Arthritis Res Ther 2019;21:120]

Although unclear, acupuncture has been reported to relieve knee OA pain by preventing cortical thinning and a decline in functional connectivity in major pain-related areas. As a result, pain is modulated in the descending pain modulatory pathway. [Sci Rep 2014;4:6482]

The investigators called for more studies to shed light on the therapeutic mechanisms of acupuncture for knee OA.