Study Finds That Intensity of Walking Affects Risk of Knee Replacement

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Patients with knee osteoarthritis (OA) who walk with moderate to vigorous intensity may lower their risk of total knee arthroplasty (TKA), according to new research presented at the annual meeting.

OA is a common, painful joint disease that usually affects people during middle age or later. It is characterized by a breakdown of the cartilage, bony changes in joints, deterioration of tendons and ligaments, and inflammation of the synovium. Knee arthroplasty, or joint replacement, is a common treatment for knee OA.

The researchers sought to explore whether walking more increases a patient’s risk of further structural damage in the knee joint and therefore risk of TKA. Although previous research has been conducted on the topic, the team from the University of Delaware suspected that different levels of walking intensity may have contributed to contradictory evidence. Therefore, they conducted a 5-year study to reveal associations between walking intensity and TKA in adult patients who had or were at risk for knee OA.

“Walking may exacerbate knee pain and further make things worse, but on the  other hand, walking is helpful to build and maintain strength and may prevent the development of difficulty functioning,” said Hiral Master, PT, MPH, a PhD candidate at the University of Delaware.

The researchers used data from the Osteoarthritis Initiative and included participants who had not had TKA at or before a 48-month follow-up visit. They defined walking intensity by step cadence as measured by an accelerometer:

  • Fewer than one step per minute was defined as non-walking.
  • 1-49 steps per minute was defined as very light walking.
  • 50-100 steps per minute was defined as light walking.
  • More than 100 steps per minute was defined as moderate to vigorous walking.

The study measured the months between the baseline visit and the date of surgery (if within 5 years) or the 108-month visit. Participants who did not receive TKA at the 108-month visit or who were lost to follow-up were removed from analyses. The study included 1,854 participants who had not received TKA; the mean age was 65 years, their mean body mass index was 28.4 kg/m2, and 55% were female. Participants wore their accelerometers for at least 4 of 7 days.

Over the course of 5 years, 108 participants underwent TKA. Participants who had replaced 5 minutes per day of non-walking time with 5 minutes per day of walking at a moderate to vigorous intensity reduced their risk of TKA by 16 percent, the authors said. Walking at a very light or light intensity had no effect. The researchers found similar results when they analyzed samples of patients with radiographic and symptomatic knee OA.

Based on the findings, the authors urged clinicians to encourage their patients with knee OA or at high risk for the condition to walk briskly 5 to 10 continuous minutes every day.