Lack of Physical Activity Level Alteration Post-Total Knee Arthroplasty

Background: More than 650,000 total knee arthroplasties are performed annually to alleviate pain and disability associated with osteoarthritis; a chronic, degenerative condition that compromises the quality of life of 37% of adults over age 60. Despite the decrease in knee pain commonly associated with total knee arthroplasty, little is known about subsequent alterations in physical activity level. Inadequate physical activity in total knee arthroplasty patients has previously been found to result in increased weight gain, decreased functional performance, increased incidence and/or progression of co-morbid conditions, and progression of knee/hip osteoarthritis.

Purpose: The purpose of this study was to examine the impact of total knee arthroplasty on physical activity 1 month and 6 months post-surgery as compared to pre-surgery.

Methods: Fifteen patients with osteoarthritis (aged 68 ± 12 years, 9 females, 6 males, body mass index = 27.14 ± 2.58 kg/m2) undergoing unilateral total knee arthroplasty were enrolled. Physical activity (steps/day) was measured using hip-mounted monitors (ActiGraph GT1M, GT3X)worn for one week, at each time point. Exclusion criteria included other lower limb orthopaedic conditions or neurological impairments expected to act as barriers to physical activity.

Results: Physical activity was unaltered upon comparison of pre-total knee arthroplasty (4,218 ± 2,302 steps/day) to 1 month post- (3,370 ± 1,596 steps/day, p > 0.05) and 6 months post-total knee arthroplasty (4,783 ± 2,116 steps/day, p > 0.05) values.

Conclusion: The present findings suggest a lack of increase in physical activity despite previous studies’ indications of significant reduction in knee pain 6 months post-total knee arthroplasty. A need exists for novel interventions aimed at decreasing the incidence and/or progression of co-morbid conditions in patients undergoing total knee arthroplasty. Such interventions may benefit from the inclusion of a behavioral modification on program aimed at enhancing self-managed physical activity.

Supported by the NIH (K23 AG029978, R01 HD065900)