Patients Who Introduce Moderate-to-Vigorous Intensity Walking May Avoid Total Knee Replacement

Periods of moderate-to-vigorous intensity walking (instead of nonwalking) was associated with less risk of total knee replacement over 5 years in patients who have, or who are at high risk of, osteoarthritis of the knee, according to the results of a new study from investigators at the University of Delaware.¹

More than 600,000 total knee replacements are performed each year in the United States.² Conflicting data exists on whether walking more is associated with greater structural damage or risk of total knee arthroplasty as the intensity at which an individual walks can vary. Therefore, investigators set out to determine whether there was an association between the intensity of walking and risk of total knee arthroplasty.

“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 study co-author Hiral Master, PT, MPH, a PhD candidate in biomechanics and movement science at the University of Delaware in a statement. “We wanted to know if walking was helpful or harmful for getting a knee replacement for people who have knee osteoarthritis.”

The team analyzed data on 1854 participants in the Osteoarthritis Initiative (OAI) who had not undergone a total knee arthroplasty at or before a 48-month follow-up visit ([mean ± SD] age: 65 ± 9.1 years, BMI: 28.4 ± 4.8 kg/m², 55% female). They quantified the time an individual spent in different walking intensities using step cadences recorded by an accelerometer (Actigraph GT1M). Less than 1 step per minute was defined as nonwalking, while between 1 and 49 steps per minute was defined as very-light walking; 50 to 100 steps per minute was defined as light walking; and more than 100 steps per minute was defined as moderate-to-vigorous walking.

The time to total knee arthroplasty “was quantified in months from the baseline visit date to total knee arthroplasty date if received in the subsequent 5 years, (ie, until the 108-month OAI visit),” study authors wrote. Those participants who did not have total knee arthroplasty by the 108-month visit and those who were lost to follow-up were not included.

Using isotemporal substitution within a Cox proportional hazard model, the investigators examined the effects of substituting very-light, light, or moderate-to-vigorous walking in place of non-walking and the impact on the risk of total knee arthroplasty over 5 years.

The results indicated that out of the 1854 patients without total knee arthroplasty included in the analysis who wore the accelerometer for 4 days or more, 108 participants received a total knee arthroplasty over 5 years. Substituting 5 minutes of moderate-to-vigorous walking instead of nonwalking reduced the risk of total knee arthroplasty by 16% (hazard ratio 0.84, 95% confidence interval [0.72, 0.98]).

Conversely, substituting in very-light or light intensity walking for non-walking had no effect.

The investigators state that these findings suggest that “small changes in walking behavior could delay the need for total knee arthroplasty in people with or at high risk of knee osteoarthritis.”

The study was presented at the 2018 ACR/ARHP Annual Meeting, October 19-24, 2018, in Chicago, Illinois.

References:

1. Master H, Thoma L, Christiansen M, Mathews D, Macri E, Ziegler M, Stefanik JJ, White D. Friend or Foe: Does Walking at Higher Intensities Increase or Decrease the Risk of Total Knee Arthroplasty over Five Years? [abstract]. Arthritis Rheumatol. 2018; 70 (suppl 10). https://acrabstracts.org/abstract/friend-or-foe-does-walking-at-higher-intensities-increase-or-decrease-the-risk-of-total-knee-arthroplasty-over-five-years/. Accessed October 21, 2018.
2. Foran, JRH. Treatment. Total Knee Replacement. Ortho info. https://orthoinfo.aaos.org/en/treatment/total-knee-replacement/. Updated August 2015. Accessed October 21, 2018.