What’s hot in knee OA rehab research

TORONTO – Emerging evidence indicates that patients with knee osteoarthritis who engage in high-intensity interval training obtain significantly greater improvement in physical function than with conventionally prescribed moderate-intensity exercise, Monica R. Maly, PhD, said at the OARSI 2019 World Congress.

^{Bruce Jancin/MDedge News}

Dr. Monica R. Maly

This was one of the key conclusions she and her coworkers drew from their analysis of the past year’s published research on diet and exercise interventions to improve outcomes in patients with OA, where obesity and physical inactivity figure prominently as modifiable lifestyle factors.

Another finding: Exercise interventions are where all the action is at present in the field of lifestyle-modification research aimed at achieving better health-related quality of life and other positive outcomes in OA. Dietary interventions are simply not a hot research topic. Indeed, her review of the past year’s literature included 38 randomized, controlled trials (RCTs) and 15 meta-analyses and systematic reviews – and all 38 RCTs addressed exercise interventions.

“It’s interesting to note that we found no new RCT data on diet to modify obesity in OA in the past year,” Dr. Maly said at the meeting sponsored by the Osteoarthritis Research Society International.

Additionally, 32 of the 38 RCTs devoted to exercise interventions for OA focused specifically on knee OA, noted Dr. Maly of the department of kinesiology at the University of Waterloo (Ont.).

Aerobic exercise dosage and intensity

Australian investigators conducted a pilot randomized trial of high-intensity interval training (HIIT) versus more conventional moderate-intensity exercise to improve health-related quality of life and physical function in 27 patients with knee OA. The exercise programs involved unsupervised home-based cycling, with participants requested to do four roughly 25-minute sessions per week for 8 weeks.

The two exercise intensity groups showed similar gains in health-related quality of life as assessed by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). However, the HIIT group showed significantly greater improvement in physical function as measured on the Timed Up and Go test (PeerJ. 2018 May 9;6:e4738).

Dr. Maly noted that adherence to the home-based exercise programs was a challenge: Only 17 of the 27 patients completed the 8-week Australian study, for a 37% dropout rate. However, most study withdrawals were because of family-related issues, illness, or injuries unrelated to cycling, with no signal that HIIT placed knee OA patients at higher injury risk.

Other investigators performed a systematic review of 45 studies in an effort to generate evidence-based guidance about the optimal exercise dosing in order to improve outcomes in knee OA patients. They concluded that programs comprising 24 therapeutic exercise sessions over the course of 8-12 weeks resulted in the largest improvements in measures of pain and physical function. And, importantly, one exercise session per week conferred no benefits (J Orthop Sports Phys Ther. 2018 Mar;48[3]:146-61).

“Frequency probably matters,” Dr. Maly observed.

Patients and their physicians often wonder if long-term, land-based exercise might have deleterious impacts on joint structure in patients with knee OA. Reassurance on this score was provided by a recent meta-analysis of RCTs that concluded, on the basis of moderate-strength evidence, that exercise therapy of longer than 6 months duration had no adverse effect on tibiofemoral radiographic disease severity, compared with no exercise. Nor was there evidence of a long-term-exercise–associated deterioration of tibiofemoral cartilage morphology or worsening of synovitis or effusion. Plus, the meta-analysis provided limited evidence to suggest long-term exercise had a protective effect on the composition of patellar cartilage (Semin Arthritis Rheum. 2019 Jun;48[6]:941-9).

“While there was a little bit of evidence suggesting that long-term exercise could worsen bone marrow lesions, really there was no other evidence that it could change the structure of a joint,” according to Dr. Maly.