Promotion and Support for Physical Activity Maintenance Post Total Hip Arthroplasty (PANORAMA). A Pragmatic, Randomized, Controlled, Trial.

Total hip arthroplasty (THA) is considered an efficacious procedure for relieving pain and disability in patients with hip osteoarthritis. However, 6-12 months post-surgery physical activity level is unchanged compared to pre-surgery and still considerably lower than that of healthy peers. Increasing physical activity after THA may enhance the outcome of the THA because a graded relationship between physical activity level and functional performance has been documented. Six-8 months after THA physical function is only recovered to about 80% of that of healthy peers and older adults still seem to be at increased risk of frailty. Furthermore, these patients continue to impose higher healthcare costs than an age- and sex-matched reference population which potentially could be related to the functional status that is not completely regained. Finally, patients with hip osteoarthritis can have extensive comorbidity thus increasing physical activity after THA could be a simple and relatively inexpensive method for improving general health, which in turn may decrease healthcare costs.

The reasons for the lack of increase in physical activity despite increased capability after THA are unknown but it may be related to the sedentary behavior adopted by the patients prior to surgery and uncertainty. A systematic review has illuminated that patient-reported barriers to engaging in physical activity after THA are largely related to limited or inadequate information or education culminating in uncertainty about 'doing the right thing' for both the individual's recovery and the longevity of the joint replacement.

Few studies have investigated the effects of specific interventions to increase physical activity after THA. Promising results have been shown from physical activity sensors in combination with e.g. goal setting. None of these studies have addressed the patient-reported barriers to physical activity regarding uncertainty and limited education.

This trial aims to investigate the effect of adding a pedometer-driven, behavior change intervention to usual rehabilitation care 3 months after THA to increase physical activity compared to usual rehabilitation care alone (control). Outcomes are taken 3 (baseline), 6 (after the intervention period) and 12 months after THA (follow-up).

Hypothesis: the behavior change intervention will increase the proportion that completes ≥8,000 steps per day 6-month post-surgery to 50% versus 30% in the control group.