Effectiveness of Acupuncture for Pain and Knee Osteoarthritis: the Evidence in Full

In the March 2015 issue of PT in Motion,¹ we published a response to an article by Hinman et al (2014) entitled, Acupuncture for Knee pain: A Randomized Clinical Trial.² We specifically cited a number of randomized controlled trials, systematic reviews, meta-analyses and Cochrane reviews that reported findings contrary to those published by Hinman et al; furthermore, we offered a possible explanation for the discrepancy. That is, Hinman et al did not radiographically confirm the clinical diagnosis of knee osteoarthritis, resulting in a sample of patients with mixed etiology, thereby jeopardizing the internal validity of the study. Nevertheless, in the August 2015 issue of PT in Motion, Venere and Ridgeway published a letter, titled Acupuncture Effect Not Clinically Meaningful, taking issue with our “strong support” for the use of acupuncture for the treatment of pain, stating, “There are many lessons to be learned from the acupuncture literature. The fact that it is an effective treatment for patients in pain, however, is not one of them”.³ More specifically, Venere and Ridgeway narrowly focused their claims on the partial findings of a single publication⁴ and supported their position with just 5 unique references. They further suggested that we conflated a clinically relevant benefit for acupuncture in the treatment of knee osteoarthritis by misinterpreting the literature. Therefore, the purpose of this article is to directly respond to these claims in a public forum, so as to better inform physical therapists and other health care providers of the large and well developed body of evidence that underpins the use acupuncture for the treatment of chronic pain and specifically for the management of knee osteoarthritis.

ACUPUNCTURE FOR PAIN

Venere and Ridgeway³ claim acupuncture is not an effective treatment strategy for pain; however, as already detailed and well referenced in the 2014 literature review by Dunning et al,⁵ a large number of studies have demonstrated the effectiveness of acupuncture for reducing pain and disability in patients with knee osteoarthritis,^{4, 6-18} hip osteoarthritis,^19-23 piriformis syndrome,²⁴ carpal tunnel syndrome,^25-31 migraines,^32-38 tension type headaches,^{34, 35} temporomandibular disorder,^39-45 shoulder pain,^46-48 neck pain,^49-60 low back pain^61-71 and plantar fasciitis.^{72, 73} Moreover, a number of studies have attempted to delineate the physiologic processes responsible for pain reduction following acupuncture. While needling muscle tissue with trigger points in an effort to elicit localized twitch responses has been shown to reduce pain and inflammation in the short-term,^{74, 75} it has also been found to systemically reduce pain by activating opioid-based pain reduction^76-79 that is mediated by endogenous cannabinoids^80-82 and the sympathetic nervous system,^{83, 84} and to activate non-opioid pain relief via serotonin and norepinephrine pathways in the brain stem.^{76, 85-87} In addition, acupuncture triggers the HPA-axis centrally⁸⁸ and the CRH-POMC-corticosteroid axis locally⁸⁹ to inhibit cox-2 and reduce inflammatory cytokines.

At a cellular level, electroacupuncture has been found to stimulate immune cells, fibroblasts and keratinocytes to release CGRP and substance-P,⁹⁰ altering CGRP stimulation of TTX receptors to reverse hyperalgesia.⁹¹ Furthermore, acupuncture encourages the supraoptic nucleus to release oxytocin to quiet ASIC receptors peripherally and stimulate opioid interneurons spinally.^92-94 Moreover, acupuncture facilitates mechanotransduction of fibroblasts and peripheral nerves via TRPV1⁹⁵ and P2X/Y-mediated intercellular Ca²⁺ wave propagation and subsequent activation of the nucleus accumbens, and this inhibits spinal pain transmission via glycinergic and opioidergic interneurons.^{96, 97} The increased ATP is metabolized to adenosine, which activates P1 purinergic receptors, events considered key to acupuncture mediated analgesia and rho kinase-based tissue remodeling.⁹⁸

ACUPUNCTURE FOR KNEE OSTEOARTHRITIS

We stated in a previous literature review⁵ and in our letter to PT in Motion² that the current body of evidence strongly supports the use of acupuncture for treating the pain, stiffness and disability associated with knee osteoarthritis; that is, multiple high quality RCTs, systematic reviews and meta analyses have concluded such. Zhang et al⁹⁹ cited a 69% consensus following a Delphi study recommending the use of acupuncture for the symptomatic treatment of joint OA and reported a moderate effect size for the modality (i.e. acupuncture). Witt et al¹⁹ reported on the data from 304,674 patients, and in short, those treated with acupuncture in addition to usual care showed significantly greater improvements in pain compared to patients who received usual care only, demonstrating acupuncture is an effective adjunct to usual care. Additionally, the acupuncture group showed significantly greater pain reduction compared to the wait list control group. In a 2013 comprehensive network meta-analysis, Corbett et al¹⁷ evaluated 22 interventions across 114 RCTs for treatment of pain due to osteoarthritis of the knee, and based on a primary sensitivity analysis of better quality studies, acupuncture was found to be one of the more effective physical treatments for reducing pain in the short term.¹⁷ Moreover, verum or real acupuncture was significantly superior for reductions in pain when compared to standard care and sham acupuncture. In addition, acupuncture was significantly better than muscle strengthening exercise, weight loss, aerobic exercise, and no intervention.¹⁷ Notably, Corbett et al¹⁷ alluded to the pitfalls of sham controlled acupuncture trials and reported that the effects of acupuncture in their study may have been underestimated due to the inclusion of 2 large sham controlled studies that used a placebo that likely was physiologically active.

Importantly, these trials are in agreement with the large scale 2010 Cochrane review on acupuncture for knee osteoarthritis by Manheimer et al¹⁸ that compared the effects of verum acupuncture with sham acupuncture, an active treatment, and waitlist control from 12 RCTs. Although the effects of verum acupuncture versus sham acupuncture were statistically significant in the short term and at 6 months, the benefits were nevertheless considered clinically irrelevant.¹⁸ However, a subgroup analysis found the effects of verum acupuncture were clinically relevant when compared to several active treatments and waitlist controls, and the authors suggest that patients with osteoarthritis will find meaningful benefits from acupuncture.¹⁸ In addition, and according to the 2012 study by Vickers et al⁴ that evaluated data from 17,922 individual patients with 1 of 4 conditions (non-specific back or neck pain, osteoarthritis, shoulder pain or chronic headache), acupuncture was found to be superior to sham acupuncture and no-acupuncture controls. Notably, Vickers et al⁴ concluded that while there are specific effects of acupuncture beyond placebo, non-specific effects also exist. Furthermore, it should be noted that several of the largest trials in this study had a sham intervention arm that likely was active.⁴ Therefore, according to the findings of multiple RCTs and systematic reviews, acupuncture demonstrates both effectiveness and efficacy as an intervention for the treatment of pain.

ELECTROACUPUNCTURE FOR PAIN

Interestingly, the addition of electricity to acupuncture may further enhance outcomes for treating chronic pain.¹⁰⁰ Evidence from multitude trials supports the use of electroacupuncture for its physiological effects, predominately opioid analgesia both peripherally¹⁰¹ and centrally.¹⁰² Electrical stimulation to local points around the knee in patients with osteoarthritis has been a feature of the strongest acupuncture trials. Loaiza et al¹⁰³ concluded electroacupuncture may increase vasodilation, thereby countering the microvascular restrictions seen in knee and shoulder osteoarthritis. In a randomized controlled trial of 120 patients with knee osteoarthritis, Mavrommatis et al¹³ found verum electroacupuncture was significantly better than a non-penetrating sham for pain reduction at week 8, and the benefits continued for at least 1 month after treatment cessation.¹³ Additionally, a subgroup analysis in the study by Manheimer et al¹⁸ found that trials using electroacupuncture for the treatment of knee osteoarthritis showed a larger effect size than trials using manual acupuncture only.¹⁸

CONCLUSIONS

Notably, we originally submitted a 2762 word letter to PT in Motion for our response to Hinman et al;² however, the editor, Donald Tepper, required that the article be cut down to 750 words. Interestingly, our 750 word submission was further reduced by Mr. Tepper himself, without our consent or knowledge, and published in the March 2015 issue of PT in Motion with just 240 words.¹ Moreover, it should also be noted that Mr. Tepper had agreed to post our original 2762 word response online at PT in Motion, but to our knowledge, this was never done. Importantly, a Conflict of Interest Statement declaring our faculty positions with the Dry Needling Institute and the American Academy of Manipulative Therapy Fellowship in Orthopaedic Manual Physical Therapy program was submitted to PT in Motion but was never published by Mr. Tepper.

To our knowledge, Venere and Ridgeway have no formal training in acupuncture, would not be considered as academic or clinical experts in the use of acupuncture for the treatment of pain and disability in musculoskeletal conditions—i.e. they work in home health and acute care settings, respectively—and have yet to publish a single article in a peer-reviewed journal on the topic. Therefore, considering the 3 pillars of evidence-based practice as originally put forward by Sackett,¹⁰⁴ Venere and Ridgeway³ have provided nothing more than their own personal opinions on the subject of acupuncture induced hypoalgesia. Nevertheless, we do appreciate their willingness to engage in an open forum and thank them for sharing their views on acupuncture.

AUTHORS

James Dunning, DPT, MSc (Manip Ther), MAACP (UK), FAAOMPT
Director, AAMT Fellowship in Orthopaedic Manual Physical Therapy
President, Alabama Physical Therapy & Acupuncture, Montgomery, AL

Raymond Butts, PhD, DPT, MSc (NeuroSci), Cert. DN, Cert. SMT
Senior Instructor, Spinal Manipulation Institute & Dry Needling Institute
Senior Faculty, AAMT Fellowship in Orthopaedic Manual Physical Therapy
Atlanta, GA

Thomas Perreault, DPT, OCS, Cert. DN, Cert. SMT
Clinic Director, Portsmouth Physical Therapy, Portsmouth, NH
Senior Faculty, AAMT Fellowship in Orthopaedic Manual Physical Therapy

Firas Mourad, PT, OMT, Cert. SMT, Dip. Osteopractic
Lecturer, Master in Sports Rehabilitation Program, University of Pisa, Italy
Senior Faculty, AAMT Fellowship in Orthopaedic Manual Physical Therapy

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