TORONTO – Eight physical therapy sessions spread over 4-6 weeks in patients with knee osteoarthritis provided significantly greater and longer-lasting improvements in both pain and function than an intra-articular corticosteroid injection in a randomized, multicenter trial with 12 months of prospective, blinded follow-up, Daniel I. Rhon, DPT, DSc, reported at the OARSI 2019 World Congress.
Bruce Jancin/MDedge News
Dr. Daniel I. Rhon
“Considering the very low utilization rate of physical therapy prior to arthroplasty, perhaps we should more often give it a try before declaring that conservative care has failed and moving on to surgical management,” concluded Dr. Rhon, director of the primary care musculoskeletal research center at Brooke Army Medical Center in San Antonio.
Various studies have shown that close to 50% of patients with knee OA receive one or more intra-articular corticosteroid injections within 5 years prior to undergoing total knee arthroplasty, compared with physical therapy in only about 10% of patients, even though most guidelines rate both as first-line therapies, he noted at the meeting sponsored by the Osteoarthritis Research Society International.
He presented a randomized trial of 156 patients who sought treatment for pain caused by knee OA at army medical center primary care clinics. To his knowledge, this was the first-ever randomized, head-to-head comparison of the effectiveness of a physical therapy regimen versus corticosteroid injections for knee OA. Because he and his coinvestigators wanted a pragmatic study giving each treatment strategy its due, booster therapy was available to patients who requested it. Patients in the corticosteroid arm were able to receive up to two additional spaced intra-articular injections as needed, while those assigned to the individualized manual physical therapy intervention, which utilized exercises targeting the typical strength and movement deficits found in patients with knee OA, could have up to three additional sessions. At the outset, all participants received education about the benefits of regular low-impact physical activity, weight reduction, and strength and flexibility exercises.
The two treatment groups were comparable except that the physical therapy group had a longer disease duration – a mean of 123 months as compared with 89 in the corticosteroid group – and more radiographically severe disease. Indeed, 60% of patients randomized to physical therapy were Kellgren-Lawrence scale grade III-IV, versus 45% of those assigned to intra-articular corticosteroid injection.
The primary outcome in the study was change in Western Ontario & McMaster Universities Arthritis Index (WOMAC) score at 12 months. As early as 4 weeks into the study, the physical therapy group showed significantly greater improvement than in the comparison arm: from a mean baseline WOMAC score of 115 to 42.9 at 4 weeks, 42.5 at 6 months, and 38.4 at 1 year. The comparable figures in the intra-articular corticosteroid group were 113.3 at baseline, 53.3 at 4 weeks, 57.9 at 6 months, and 53.8 at 1 year.
“Physical therapy provided clinically important benefit that was superior to corticosteroid injection out to 1 year, while also providing the short-term benefit typically sought from corticosteroid injection,” Dr. Rhon observed.
The median improvement in WOMAC score at 1 year was 52% in the corticosteroid group and 71% in the physical therapy arm. About 59% of the physical therapy group experienced at least a 50% reduction in WOMAC score at 12 months, as did 38% of intra-articular injection recipients. The number needed to treat with physical therapy instead of intra-articular corticosteroids in order for one additional patient to achieve at least a 50% improvement in WOMAC score through 1 year of follow-up was four.
“We were a little bit surprised that there was such a large effect size in the study. The effect size in the injection group was bigger than reported in some other trials,” according to Dr. Rhon.
In terms of downstream utilization of health care, there were two knee arthroplasties and one arthroscopy in the study population, all in the intra-articular corticosteroid group. Seven patients in the intra-articular steroid group received more than three injections, including one patient with nine. And 13 patients in the physical therapy arm went outside the study in order to receive at least one corticosteroid injection.
One audience member pointed out that the physical therapy approach offers an important side benefit: In addition to improving pain and function, the exercise regimen has a favorable effect on comorbid metabolic diseases commonly associated with knee OA.
“An injection doesn’t achieve that,” he noted.
Dr. Rhon reported having no financial conflicts of interest regarding the randomized trial, sponsored by Madigan Army Medical Center. He receives research funding from the National Institutes of Health and the Congressionally Directed Medical Research Programs.
SOURCE: Rhon DI et al. Osteoarthritis Cartilage. 2019 Apr;27[suppl 1]:S32, Abstract 13