Rates of radiographic knee osteoarthritis similar between runners, non-runners
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Key takeaways:
- Runners do not seem to have more prevalence of knee osteoarthritis than non-runners.
- Non-runners may be at increased risk of requiring total knee arthroplasty compared with runners.
Moderate-distance runners and non-runners alike demonstrate similar rates of radiographic knee osteoarthritis, according to systematic review data published in the Orthopaedic Journal of Sports Medicine.
The researchers additionally concluded that non-runners in fact experience a significantly higher prevalence of knee pain, as well as possibly a higher risk for total knee replacement, compared with runners.
“This is kind of a classic question that we get from patients all the time,” Matthew J. Kraeutler, MD, of the department of orthopedics and sports medicine at Houston Methodist Hospital, in Texas, told Healio. “Patients come in with early arthritis of the knee joint and they say, ‘Can I keep running, will running make my knee worse?’ and we wanted to answer that question.”
To determine if runners have a higher incidence of knee pain or OA compared with nonrunners, Kraeutler and colleagues conducted a systematic literature review of the PubMed, Embase and the Cochrane Library databases through Oct. 3, 2021. The search was conducted using the terms “knee and osteoarthritis and (run or running or runner).” Studies that evaluated the impact of running on knee OA formation, or the accumulation of chondral damage, based on imaging or patient-reported outcomes were included. Studies were excluded if they did not evaluate knee damage, investigated knee damage in non-humans or were not in English.
Outcomes of interest included patient-reported and radiological outcomes. Two of the included studies used the Knee Injury and Osteoarthritis Outcome Score. Another study used the Health Assessment Questionnaire Disability Index to report patient-reported outcomes. Regarding radiographic evidence, studies used the Kellgren-Lawrence scale, MRI T2 mapping, the MRI Osteoarthritis Knee score, the Ahlback criteria and the Osteoarthritis Research Society International Atlas.
The researchers included a total of 17 studies, representing 7,194 runners and 6,947 non-runners, in their analysis. Overall, there was a “significantly higher prevalence” of knee pain in the non-runner group, compared with runners (P < .0001), the researchers wrote. Although a single study demonstrated higher levels of osteophytes in the tibiofemoral and patellofemoral joints in the runner group, “multiple” studies showed no real difference in the presence of radiographic knee OA, based on MRI, among runners vs. non-runners. Additionally, one study showed that nonrunners had an increased risk for requiring total knee replacement compared with runners (P = .014).
“The main takeaway here is that in moderate-distance runners, there is no evidence for a higher incidence of knee pain, knee OA, or a need for total knee arthroplasty at some point in life,” Kraeutler said. “In fact, there is actually some evidence that there is a lower risk for generalized knee pain in runners compared to non-runners. I think you need to look at the overall health benefits of running, and not just the effects of running on the knee joint itself. Runners are generally going to have a normal BMI and have an overall better state of health.”
Perspective
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David A. McLain, MD, MACR, FACP, FRCP
Osteoarthritis is a leading cause of worldwide disability, with OA of the knee and hip accounting for much of it. It is estimated that 250 million people globally have OA of the knee, more than half of whom are of working age (younger than 65 years). OA is associated with activity-related pain, which makes activity, particularly exercise, a difficult proposition. Physical inactivity, however, is an underappreciated causal factor of many chronic diseases, including type 2 diabetes, cardiovascular disease and dementia, all of which are associated with chronic low-grade inflammation.
Physical activity and exercise therapy not only improve symptoms and functional impairments in OA, but are also effective in preventing at least 35, and treating at least 26, chronic conditions, with one of the potential working mechanisms being exercise-induced anti-inflammatory effects. Convincing evidence from more than 50 randomized controlled trials (RCTs) in knee OA, and 10 RCTs in hip OA, supports the efficacy of land-based — as opposed to aqua-based — exercise therapy in reducing symptoms and impairments.
Aqua-based therapy also works but is less effective than land-based exercise. Compared to the two most common pharmacological pain relievers, exercise therapy seems to be at least as effective as nonsteroidal anti-inflammatory drugs, and two to three times more effective than acetaminophen, in reducing pain in knee OA. Biochemical analyses have been performed in the OA mouse and rat models, and have shown an increase in beneficial factors with exercise (IL-10, TGF-β, maresin-1, and collagen type I and II) and a decrease in detrimental factors with exercise (TRAIL, NF-κB p65, MMP-13, IL-1 β, IL-6, TNF-a, caspase-3, and NLRP3), all in articular cartilage.
Exercise can even change gene expression by micro-RNA transcription. The old expression that “exercise is medicine” has a basis in research. Muscle strengthening and programs that include combinations of strength, flexibility and aerobic exercises are more beneficial for pain and disability than general activity (eg, walking).
In my own practice, I have been remiss in recommending an exercise program for knee and hip OA supervised by a physical therapist that has the correct “dose” — or frequency, duration and intensity — of supervised and home activities. The present study’s analysis of running shows that even this level of activity does not promote OA.
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