Injecting evidence into management of knee OA

EBM Focus - Volume 15, Issue 14

Reference: N Engl J Med. 2020 Apr 9;382(15):1420-1429

Knee osteoarthritis affects as many as 1 in 8 older adults, often resulting in pain, disability, and lost earnings (Murphy et al. 2017, Cross et al. 2014). Treatment options range from ice to arthroplasty. Current guidelines give conflicting recommendations based on a tangled web of evidence. Multiple studies have found corticosteroid injections to be ineffective compared to placebo, although comparisons with other therapies are limited and trial durations relatively short (Jüni et al. 2015, Henriksen et al. 2015). Manual physical therapy, a particular form of therapy focused on hands-on mobilizing techniques to reduce pain and increase mobility, has been found to improve pain and function compared to exercise therapy (Abbott et al. 2013). Despite this evidence, more patients continue to receive injections than physical therapy referrals.

Investigators at multiple Army Medical Centers conducted a randomized trial of 156 adults aged ≥ 38 years with symptoms and radiographic evidence of knee osteoarthritis. Participants were randomized to unblinded corticosteroid injections (CSI, n = 78) or physical therapy (PT, n = 78). The CSI group received an intra-articular triamcinolone injection, with an option for additional CSI at 4 and 9 months. Participants in the PT group had 8 treatment sessions in the first 6 weeks of the trial, with the option of additional treatment sessions at 4 and 9 months. Participants had an average age of 56 years, BMI of 31, and baseline Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score of 108 (scores range from 0 to 240, with higher scores indicating more severe disease). The primary outcome was WOMAC score at 12 months; secondary outcomes included assessment of pain, function, and cost of care, all assessed at 1, 2, 6, and 12 months. A total of 7/78 (9%) patients in the CSI group had PT and 14/78 (18%) in the PT group had CSI. Three participants had knee arthroplasty and 1 had arthroscopy, all in the CSI group. Both groups had significant improvement in WOMAC scores at 12 months, but the PT group had a significantly greater improvement in pain, stiffness, and function compared to the CSI group (WOMAC 55.8 in CSI group vs. 37.0 in PT group, mean difference 18.8, 95% CI 5-32.6). The PT group had better performance on the Timed Up and Go Test and Alternate Step Test as well as the Global Rating of Change Scale at 1 year compared to the CSI group. Major adverse events were similar.

Steroid injections are not better than PT at 12 months according to this study and many others. But that’s not really why we do them. The short-term benefits in pain reduction and functional gain with steroid injections for some people may drive physicians to give the shots, and patients to request them. Perhaps PT is too time-intensive or costly (in both time and copays) for some patients and a joint injection is quicker and easier. Perhaps we want to feel like we are “doing something.” Joint injections continue to be performed, often upon request, despite the evidence disputing their long-term benefit. Perhaps it is time for the burden of proof to shift to those who advocate for steroid injections to prove the worth of this procedure.

For more information, see the topics Osteoarthritis of the Knee and Physical Therapy for Osteoarthritis of the Knee in DynaMed.

DynaMed EBM Focus Editorial Team

This EBM Focus was written by Carina Brown, MD, Assistant Professor at Cone Health Family Medicine Residency. Edited by Alan Ehrlich, MD, Executive Editor at DynaMed and Associate Professor in Family Medicine at the University of Massachusetts Medical School, Dan Randall, MD, Deputy Editor for Internal Medicine at DynaMed, and Katharine DeGeorge, MD, MS, Associate Professor of Family Medicine at the University of Virginia and Clinical Editor at DynaMed.