Knee osteoarthritis (OA) is the most prevalent musculoskeletal condition worldwide — affecting approximately 250 million people and the leading cause of functional disability in adults over 50. Standard pharmacologic treatment (NSAIDs, analgesics, intra-articular injections) provides partial pain control but carries significant long-term risks: gastrointestinal and cardiovascular toxicity of NSAIDs, controversial cartilage effects of corticosteroid injections, and inconsistent evidence for hyaluronic acid. Surgery (total arthroplasty) is reserved for advanced cases. In that context, acupuncture emerges as a non-pharmacologic alternative with a growing evidence base. A meta-analysis published in BMJ Evidence-Based Medicine — one of the most demanding evidence-based medicine journals — in November 2024, gathering 80 RCTs with 9,933 participants, not only confirms the efficacy of acupuncture but identifies two critical effect-modifying factors: the type of acupuncture (electroacupuncture vs. manual) and the treatment dose.
The study was conducted by Chuan-Yang Liu, of the Beijing Hospital of Traditional Chinese Medicine affiliated with Capital Medical University, with searches in 8 databases including PubMed, Embase, Cochrane Central, Web of Science, and Chinese databases, covering studies through November 2023. The use of network meta-analysis (NMA) is methodologically superior to conventional meta-analyses for comparing multiple interventions simultaneously — allowing comparison of electroacupuncture vs. manual acupuncture vs. sham acupuncture vs. NSAIDs vs. usual care in a single integrated analysis. The inclusion of 80 RCTs represents one of the most robust bodies of evidence ever synthesized on acupuncture for any musculoskeletal condition.
RESULTS OF THE NMA OF ACUPUNCTURE FOR KNEE OSTEOARTHRITIS (BMJ EBM, NOVEMBER 2024)
The Dose Factor: Why “More Acupuncture” Matters
The most clinically impactful finding of this NMA is the dose–response analysis: compared with NSAIDs, high-dose acupuncture demonstrated SMD of −2.30 (substantial superiority), while low-dose acupuncture had SMD of 0.32 (not significant, essentially equivalent to no effect). The dose × effect interaction was statistically significant (P<0.001). This dose–response dissociation is a robust finding: the efficacy of acupuncture is not a binary effect (works/does not work) but a continuous effect dependent on stimulus intensity. In the practice of the analyzed RCTs, “high dose” referred to the total number of needles per session, the number of sessions, and the needle retention time — parameters that the medical acupuncturist can optimize according to patient response.
The distinction between electroacupuncture (EA) and manual acupuncture (MA) is equally relevant. In direct comparison via NMA, EA demonstrated SMD of −0.75 vs. MA — and, crucially, EA was significantly superior to sham (significant p), whereas MA did not reach significance vs. sham in the global analysis. This suggests that electrical stimulation adds a specific effect component beyond the pure mechanical stimulus of the needle — possibly via greater release of beta-endorphin, dynorphin, and CGRP through electrical stimuli of specific frequency (2 Hz for endorphins; 100 Hz for dynorphin).
Durability: The Finding That Demands Maintenance
An important finding — clinically relevant for therapeutic planning — is that the study did not find evidence of sustained benefit at 26 or 52 weeks after the end of treatment when compared with sham. This does not mean that acupuncture loses its effect, but that the assessment window after active treatment did not show a difference large enough to be detected in the available studies. In practice, this guides toward a maintenance strategy: instead of a single treatment cycle expecting a permanent effect, periodic booster sessions are likely necessary to maintain functional benefit in a chronic condition such as OA.
Publication in BMJ Evidence-Based Medicine — a journal dedicated exclusively to the critical synthesis of clinical evidence — is an indicator of methodological rigor: for a meta-analysis to be accepted by that journal, the methodology must withstand scrutiny far more severe than most integrative medicine journals require. The inclusion of 80 RCTs and the subgroup analyses by type, dose, and follow-up time represent the state of the art in evidence-synthesis methodology.
Frequently Asked Questions
For patients on high-dose acupuncture, the data from this NMA show an analgesic effect superior to NSAIDs (SMD −2.30). However, the recommendation is not unilateral substitution — it is individualization: patients with contraindications to NSAIDs (gastropathy, high cardiovascular risk, kidney impairment) are priority candidates for acupuncture as the main alternative. For others, the combination of acupuncture + reduced-dose NSAIDs may be clinically more efficient than either alone. The decision should be made together with the rheumatologist or physician of reference.
The RCTs in this NMA used between 8 and 24 sessions of active treatment. Analgesic response usually appears starting at the 4th–6th session, with progressive benefit through the 12th–16th session. For moderate-grade knee osteoarthritis (Kellgren-Lawrence II–III), an initial cycle of 12–16 sessions (3 times/week for 4–6 weeks) is a reasonable reference. Patients with severe osteoarthritis (KL IV) or with an acute inflammatory component may have a slower and more variable response.
There is no direct data from this NMA on postponing arthroplasty. However, the documented functional and analgesic improvement is clinically relevant: patients with better pain control are more able to maintain muscle-strengthening exercises, which reduce OA progression and may delay the need for surgery. In clinical practice, patients with KL II–III osteoarthritis seeking alternatives before surgery are a relevant group for medical acupuncture — with the clear expectation that treatment relieves symptoms without reversing cartilage loss, and that maintenance of function is the central goal.
Fonte Original
BMJ Evidence-Based Medicine(em inglês)Founded in 1989 by physicians trained at the University of São Paulo (USP) and specialized in China, CEIMEC is a Brazilian national reference in the teaching and practice of medical acupuncture. With more than 3,000 physicians trained over 35 years, it collaborates with HC-FMUSP and is recognized by the Brazilian Medical College of Acupuncture (CMBA/AMB).