413 Robotic Arm-Assisted Bi-Unicompartmental Arthroplasty (RoBi-UKA) Versus Total Knee Arthroplasty (TKR) Using Objective Measures of Physical Activity: A Prospective, Randomised Controlled Trial (RCT)

Introduction

RoBi-UKA is a bone-conserving, cruciate-sparing alternative to TKA. Patient-reported outcome measures (PROMs) do not differentiate the procedures, and conflicting data exists on physiological gait preservation. Physical activity (PA) is an understudied phenomenon in arthroplasty, especially given its strong causal link with cardiometabolic disease and all-cause mortality. The World Health Organization (WHO) recommends at least 150–300minutes of moderate-intensity PA or 75–150minutes of vigorous-intensity PA per week to maintain health.

We compared levels of PA using a highly reliable and valid objective measure device in patients randomised to RoBi-UKA or TKR.

Method

We analysed 55 patients from a prospective, single centre, RCT. 33 received TKA and 22 underwent RoBi-UKA. The ActivPal accelerometer was worn on their dominant thigh for 24 hours per day for seven days. Data for three consecutive days was analysed at pre-op, one-year post-op and at two years. EQ-5D-3L, EuroQol, Forgotten Joint Score, New Knee Society Score, Oxford Knee Score, and UCLA scores were also collected.

Results

Moderate-to-Vigorous Physical Activity (MVPA) increased from 26.6mins/day to 28.6mins/day at one-year postop and 29.3 mins/day at two-years postop for RoBi-UKA. MVPA for TKA initially fell from 24.5mins/day to 24.2mins/day at one-year but rose to 26.6mins/day at two-years, also reflected in PROMs. No statistically significant differences in PA were seen between the two groups at any time point.

Conclusion

RoBi-UKA offers a faster recovery to PA levels which are within the weekly WHO recommendations. TKA patients drop PA to lower than arthritic levels at one-year postop but reach RoBi-UKA levels at two years.