Updated systematic review and meta-analysis of acupuncture for chronic knee pain
Zhang et al. · Acupuncture in Medicine · 2017
Evidence Level
MODERATEOBJECTIVE
To assess the effectiveness and safety of acupuncture for the treatment of chronic knee pain
WHO
Patients with chronic knee pain (>3 months), predominantly osteoarthritis
DURATION
Primary follow-up at 12 weeks after randomization
POINTS
Various acupuncture protocols, including electroacupuncture and auricular acupuncture
🔬 Study Design
Acupuncture
n=304
Traditional acupuncture or electroacupuncture
Control
n=304
Waiting list, usual care, or other interventions
📊 Results in numbers
Reduction in WOMAC pain subscale
Reduction in visual analog scale (VAS)
Adverse event rate
WOMAC heterogeneity
Percentage highlights
📊 Outcome Comparison
WOMAC pain subscale (12 weeks)
Visual Analog Scale (12 weeks)
This study analyzed 19 trials of acupuncture for chronic knee pain. The findings suggest that acupuncture may reduce pain at 12 weeks, but the evidence is still limited because of the variable quality of the studies.
Article summary
Plain-language narrative summary
This updated systematic review and meta-analysis examined the effectiveness and safety of acupuncture for the treatment of chronic knee pain, a common condition that particularly affects older patients with osteoarthritis. Chronic knee pain affects approximately 25% of adults over 45 years of age, causing significant disability, reduced quality of life, and high healthcare costs. The investigators conducted a comprehensive search across eight databases from inception through June 2017, including MEDLINE, EMBASE, Cochrane CENTRAL, CINAHL, and four Chinese medical databases. Randomized clinical trials comparing acupuncture as monotherapy or as an adjuvant intervention versus non-acupuncture interventions in patients with chronic knee pain (defined as duration greater than 3 months) were included.
The primary outcome was pain intensity measured by visual analog scale (VAS), WOMAC pain subscale, and an 11-point numeric rating scale. Secondary outcomes included quality of life (SF-36) and adverse events. Study quality was assessed using Cochrane risk-of-bias criteria and the STRICTA checklist. Of 3,571 studies initially identified, 19 trials were included in the systematic review, with data from 17 studies available for meta-analysis.
The studies were published between 1992 and 2014, with sample sizes ranging from 20 to 712 participants. Two studies were conducted in the United States, three in Germany, four in China, three in the United Kingdom, and one each in Australia, Japan, Greece, Iran, Thailand, and Denmark. Thirteen studies compared acupuncture as primary treatment versus various controls, including waiting list, no treatment, pharmacologic interventions, and standard care. Three studies tested electroacupuncture versus medications, one study used auricular acupuncture versus autogenic training, and two studies evaluated acupuncture as an adjuvant intervention.
Between 4 and 23 acupuncture sessions were delivered over periods of 2 to 26 weeks. The meta-analysis of effectiveness data showed that acupuncture was associated with a significant reduction in chronic knee pain at 12 weeks on the WOMAC pain subscale (mean difference -1.12, 95% CI -1.98 to -0.26, I²=62%, 3 studies, 608 participants) and on the VAS (mean difference -10.56, 95% CI -17.69 to -3.44, I²=0%, 2 studies, 145 patients). Regarding safety, no difference was found between acupuncture and control groups (risk ratio 1.08, 95% CI 0.54 to 2.17, I²=29%). Quality of life measured by the SF-36 showed significant improvement in some studies, but results were inconsistent across different time points.
The methodological quality of the included studies had important limitations. Fifteen trials specified the randomization method, while four studies only stated that participants were randomized without details. Nine studies did not report allocation concealment. Because these were effectiveness trials, blinding of participants and therapists was not considered applicable, but nine studies failed to provide information on blinding of outcome assessors.
Twelve studies had high risk of bias due to incomplete outcome data, including high dropout rates and incomplete reporting. Seven studies did not report any safety information. Regarding completeness of the STRICTA checklist, all studies reported the rationale for acupuncture well, except that eight studies did not cite literature sources to justify the therapeutic approach. Needling details were inconsistently reported: only 6 studies reported the number of needles used, 9 studies reported insertion depths, 12 studies reported elicited responses and degree of stimulation, 17 studies reported needle retention time, and 15 studies reported the type of needle used.
Regarding practitioner background, only 5 studies reported the duration of relevant training, 6 studies the extent of clinical experience, and only 1 study reported the therapists' expertise in the specific condition. The clinical implications suggest that acupuncture may be effective for relief of chronic knee pain at 12 weeks after administration, based on current evidence. However, given the heterogeneity and methodological limitations of the included studies, strong conclusions about the effectiveness of acupuncture for chronic knee pain cannot currently be drawn. Acupuncture appears to have a satisfactory safety profile, although additional studies with larger numbers of participants are needed to confirm the safety of the technique.
Strengths
- 1Comprehensive search across multiple databases without language restrictions
- 2Protocol prospectively registered in PROSPERO
- 3Detailed methodological quality assessment using Cochrane criteria
- 4Safety analysis included in the assessment
- 5Use of the STRICTA checklist to evaluate reporting of acupuncture interventions
Limitations
- 1Only a small number of high-quality and consistent studies could be included
- 2High heterogeneity across studies (I²=62%)
- 3Significant variation in measurement time points
- 4Overall unsatisfactory methodological quality of the included studies
- 5Limited data for meta-analyses owing to differing intervention comparisons
Expert Commentary
Dr. Marcus Yu Bin Pai
MD, PhD · Pain Medicine · Physical Medicine and Rehabilitation · Medical Acupuncture
▸ Clinical Relevance
Chronic knee pain from osteoarthritis is one of the most prevalent conditions in any physiatry or rehabilitation service, affecting roughly 25% of adults over 45 years of age. This meta-analysis documents a significant reduction on the VAS of 10.56 points and on the WOMAC pain subscale of 1.12 points at 12 weeks, with a safety profile equivalent to control. In practice, these numbers translate into a viable adjunct for the osteoarthritis patient who does not tolerate anti-inflammatory drugs, who is awaiting arthroplasty, or who has declined intra-articular injection. Acupuncture fits naturally into the multimodal protocol alongside quadriceps strengthening, bracing, and pharmacologic modulation, broadening the available armamentarium without adding a burden of systemic adverse effects — which is especially relevant in polymedicated older adults.
▸ Notable Findings
The most striking result of this analysis is the VAS reduction of 10.56 points, obtained with virtually null heterogeneity between the two studies sharing that metric — which confers unusual robustness to an outcome in an acupuncture meta-analysis. The reduction on the WOMAC pain subscale, with I² of 62% and three studies totaling 608 participants, also reached statistical significance, albeit with moderate variability. Equally noteworthy is the RR of 1.08 for adverse events, whose confidence interval crosses unity, confirming that the safety of acupuncture is comparable to that of controls even across a spectrum that ranged from waiting list to pharmacologic interventions. The 4-to-23-session variation across the included protocols suggests that the effect is sustained at distinct doses, a relevant point when designing individualized regimens.
▸ From My Experience
In my musculoskeletal pain outpatient practice, the typical patient with knee osteoarthritis who comes in for acupuncture has already gone through a cycle of analgesics, conventional physical therapy, and often one or two injections. I usually see a perceptible clinical response starting around the third or fourth session — reduced noise when climbing stairs, improved gait pattern, drop in VAS from the pain diary. For maintenance, I generally work with 10 to 12 sessions in the initial cycle, followed by monthly reinforcement while the patient maintains the strengthening program. I routinely combine trigger-point needling of the vastus medialis with systemic acupuncture, and the result tends to be more consistent than any single modality alone. The paper's safety finding reinforces what I see in clinic: relevant adverse events are rare and usually mild. Patients with active acute synovitis or on high-range therapeutic anticoagulation warrant heightened caution before initiation.
Full original article
Read the full scientific study
Acupuncture in Medicine · 2017
DOI: 10.1136/acupmed-2016-011306
Access original articleScientific Review
Marcus Yu Bin Pai, MD, PhD
CRM-SP: 158074 | RQE: 65523 · 65524 · 655241
PhD in Health Sciences, University of São Paulo. Board-certified in Pain Medicine, Physical Medicine and Rehabilitation, and Medical Acupuncture. Scientific review and curation of every entry in this library.
Learn more about the author →Medical disclaimer: This content is for educational purposes only and does not replace consultation, diagnosis, or treatment by a qualified professional. Some information may be assisted by artificial intelligence and is subject to inaccuracies. Always consult a physician.
Content reviewed by the medical team at CEIMEC — Integrated Centre for Chinese Medicine Studies, a reference in Medical Acupuncture for over 30 years.
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