FEMALE PATIENTS WITH END-STAGE KNEE OSTEOARTHRITIS ENGAGE IN LESS DAILY PHYSICAL ACTIVITY IN THE PRE-ARTHROPLASTY WAIT PERIOD

Knee osteoarthritis (OA) clinical symptoms and poor joint function reduce patients’ engagement in social and physical activities (PA). Following severe knee OA treatment with knee arthroplasty (KA) surgery, most patients’ PA levels remain unchanged or decrease1. Moreover, female patients with knee OA often experience more OA progression, increased pain and reduced knee function2,3. We aimed to examine the associations between PA, knee joint gait kinematics, and pain scores in patients with end-stage knee OA pre-surgery and sex-specific differences in these outcomes. Patients with end-stage knee OA on the arthroplasty waitlist were recruited. An inertial measurement unit sensor (AX6, Axivity) was anatomically aligned and fixed to the tibia of the OA-affected limb for one week to monitor patients in vivo activity. Mean amplitude deviation calculations4 were used to define average daily step counts, and percentages of time spent sedentary, doing light PA (LPA), and doing moderate-to-vigorous PA (MVPA). A 10-camera (Sony) markerless motion capture system (Theia3D Markerless) was used to capture and model the 3D limb segment poses during walking to define 3D joint kinematics (Visual3D; C-motion). The Oxford-Knee-Score-Pain-Component Score5 was collected to classify self-reported pain. Pearson's correlations were used to examine associations between gait kinematic outcomes (speed, knee flexion and adduction angle ranges of motion (KFROM, KAROM) and averages (meanKF, meanKA)) with PA outcomes (average daily step count, %sedentary, %LPA, %MVPA). T-tests were used to examine sex differences in PA levels and pain. Longitudinal data was collected for eight participants approximately three months later. Changes in PA outcomes were examined with paired t-tests, as were correlations with baseline metrics. There were no significant correlations between baseline or change in PA outcomes with knee kinematic gait outcomes (p>0.05). Self-selected gait speed was negatively correlated with pain (i.e. lower OKS pain scores) and %sedentary, and positively correlated with %MVPA. Higher baseline pain was correlated with less increase in %MVPA from time 1 to 2 (Table 1). Female patients had worse PA outcomes and higher pain at baseline than males (p Higher average self-selected walking speed and male sex were associated with less time spent sedentary and more MVPA in pre-arthroplasty patients. Higher pain was associated with lower gait speed and the female sex, consistent with literature2,5. Surprisingly, baseline pain did not impact baseline PA outcomes, but was associated with less increase in %MVPA,with a trend to less increase in daily step counts. This suggests that patients with lower pain continue to engage more in MVPA in daily living while awaiting arthroplasty than those with higher pain. Our results did not support any significant associations between knee joint kinematics during gait and PA levels during the pre-arthroplasty period despite earlier work linking gait biomechanics to PA outcomes in a moderate knee OA population6. The differences identified between male and female patients PA outcomes are important considerations for sex-specific approaches to arthroplasty management. For any figures or tables, please contact the authors directly.