Early improvement in physical activity and function after total hip arthroplasty: Predictors of outcomes

Improvements in Physical Capacity via a Wearable Sensor May Not Indicate Reductions in Real-World Sedentary Activity: A Longitudinal Post-Total Hip Arthroplasty Study

BACKGROUND AND PURPOSE

Patients with end-stage hip osteoarthritis typically elect total hip arthroplasty (THA) to improve life activity performance while clinical outcomes focus on physical capacity. However, it is unclear how improvements in life activity performance relate to improvements in physical capacity following THA. This study aimed to assess the longitudinal relationship between improvement in life activity performance (ie, decreases in sedentary time) and improvements in physical capacity (ie, increases in 6-Minute Walk [6MWT] distance) from before THA to a 6-month post-THA follow-up time point.

METHODS

This is a secondary analysis of a double-blind randomized controlled trial that enrolled individuals 50 to 85 years of age with unilateral hip osteoarthritis who underwent THA. Longitudinal variables of interest included the % of active wear time in sedentary activity using a hip-mounted wearable accelerometer-based monitor [ActiGraph wGT3X-BT] and 6MWT distance. The variables were modeled to extract predicted change scores, and simulations were used to determine if each participant had a change in sedentary time and 6MWT distance. Participants were classified on whether they improved sedentary activity time (P+: decrease in sedentary time or P-: no improvement in sedentary time) and/or 6MWT distance (C+: increased 6MWT distance or C-: no improvement in 6MWT distance). Independent sample t-tests (continuous variables) and Fisher exact tests (categorical variables) were used to compare characteristics between classification groups.

RESULTS AND DISCUSSION

All 76 participants (age: 63.9 ± 7.0 years, 64.5% male) were classified as C+, as all improved physical capacity. A majority (n = 45; 59.2%) were C+/P+, while 31 participants (40.8%) were classified as C+/ P-, and no participants were classified as C-/P+ or C-/ P-.

CONCLUSIONS

There is a noted disagreement between improvements in life activity performance versus physical capacity suggesting gains in the 6MWT are not always associated with reductions in sedentary time during recovery from THA. Improving physical capacity does not equate to decreased sedentary time. Thus, different rehabilitation targets (ie, behavior change interventions) may need to be identified and explored to enhance life activity performance following THA that may better align with patient performance goals.

Stepping Beyond Counts in Recovery of Total Hip Arthroplasty: A Prospective Study on Passively Collected Gait Metrics

Gait quality parameters have been used to measure recovery from total hip arthroplasty (THA) but are time-intensive and previously could only be performed in a lab. Smartphone sensor data and algorithmic advances presently allow for the passive collection of qualitative gait metrics. The purpose of this prospective study was to observe the recovery of physical function following THA by assessing passively collected pre- and post-operative gait quality metrics. This was a multicenter, prospective cohort study. From six weeks pre-operative through to a minimum 24 weeks post-operative, 612 patients used a digital care management application that collected gait metrics. Average weekly walking speed, step length, timing asymmetry, and double limb support percentage pre- and post-operative values were compared with a paired-sample t-test. Recovery was defined as the post-operative week when the respective gait metric was no longer statistically inferior to the pre-operative value. To control for multiple comparison error, significance was set at p < 0.002. Walking speeds and step length were lowest, and timing asymmetry and double support percentage were greatest at week two post-post-operative (p < 0.001). Walking speed (1.00 ± 0.14 m/s, p = 0.04), step length (0.58 ± 0.06 m/s, p = 0.02), asymmetry (14.5 ± 19.4%, p = 0.046), and double support percentage (31.6 ± 1.5%, p = 0.0089) recovered at 9, 8, 7, and 10 weeks post-operative, respectively. Walking speed, step length, asymmetry, and double support all recovered beyond pre-operative values at 13, 17, 10, and 18 weeks, respectively (p < 0.002). Functional recovery following THA can be measured via passively collected gait quality metrics using a digital care management platform. The data suggest that metrics of gait quality are most negatively affected two weeks post-operative; recovery to pre-operative levels occurs at approximately 10 weeks following primary THA, and follows a slower trajectory compared to previously reported step count recovery trajectories.

Objectively Measured Physical Activity, Sedentary Behavior and Functional Performance before and after Lower Limb Joint Arthroplasty: A Systematic Review with Meta-Analysis

Patients after joint arthroplasty tend to be less physically active; however, studies measuring objective physical activity (PA) and sedentary behavior (SB) in these patients provide conflicting results. The aim of this meta-analysis was to assess objectively measured PA, SB and performance at periods up to and greater than 12 months after lower limb arthroplasty. Two electronic databases (PubMed and Medline) were searched to identify prospective and cross-sectional studies from 1 January 2000 to 31 December 2020. Studies including objectively measured SB, PA or specific performance tests in patients with knee or hip arthroplasty, were included in the analyses both pre- and post-operatively. The risk of bias was assessed using the Scottish Intercollegiate Guidelines Network (SIGN). After identification and exclusion, 35 studies were included. The data were analyzed using the inverse variance method with the random effects model and expressed as standardized mean difference and corresponding 95% confidence intervals. In total, we assessed 1943 subjects with a mean age of 64.9 (±5.85). Less than 3 months post-operative, studies showed no differences in PA, SB and performance. At 3 months post-operation, there was a significant increase in the 6 min walk test (6MWT) (SMD 0.65; CI: 0.48, 0.82). After 6 months, changes in moderate to vigorous physical activity (MVPA) (SMD 0.33; CI: 0.20, 0.46) and the number of steps (SMD 0.45; CI: 0.34, 0.54) with a large decrease in the timed-up-and-go test (SMD −0.61; CI: −0.94, −0.28) and increase in the 6MWT (SMD 0.62; CI: 0.26–0.98) were observed. Finally, a large increase in MVPA (SMD 0.70; CI: 0.53–0.87) and a moderate increase in step count (SMD 0.52; CI: 0.36, 0.69) were observed after 12 months. The comparison between patients and healthy individuals pre-operatively showed a very large difference in the number of steps (SMD −1.02; CI: −1.42, −0.62), but not at 12 months (SMD −0.75; −1.89, 0.38). Three to six months after knee or hip arthroplasty, functional performance already exceeded pre-operative levels, yet PA levels from this time period remained the same. Although PA and functional performance seemed to fully restore and exceed the pre-operation levels at six to nine months, SB did not. Moreover, PA remained lower compared to healthy individuals even longer than twelve months post-operation. Novel rehabilitation protocols and studies should focus on the effects of long-term behavioral changes (increasing PA and reducing SB) as soon as functional performance is restored.