This study aimed to quantify self-reported outcomes and walking gait biomechanics in patients following primary and revision THA. The specific goals of this study were to investigate: (i) if primary and revision THA patients have comparable preoperative outcomes; and (2) if revision THA patients have worse postoperative outcomes than primary THA patients.

Forty-three patients undergoing primary THA for osteoarthritis and 23 patients undergoing revision THA were recruited and followed longitudinally for their first 12 postoperative months. Reasons for revision were loosening (73%), dislocation (9%), and infection (18%). Patients completed the Hip dysfunction and Osteoarthritis Outcome Score (HOOS), and underwent gait analysis preoperatively, and at 3 and 12 months postoperatively. A 10 camera motion analysis system (V5 Vantage, Vicon, UK) recorded marker trajectories (100 Hz) during walking at self- selected speeds. A generic lower-body musculoskeletal model (Gait2392) was scaled using principal component analysis [1] and the inverse kinematics tool in Opensim 3.3 was used to compute joint angles for the lower limbs in the sagittal plane. Independent samples t-test were used to compare patient reported outcomes between the primary and revision groups at each timepoint. Statistical parametric mapping was used to compare gait patterns between the two groups at each timepoint.

Preoperatively, patients undergoing primary THA reported significantly worse pain (p<0.001), symptoms (p<0.001), function (p<0.001), and quality of life (p=0.004). No differences were observed at 3 and 12 months postoperatively between patients who had received a primary or revision THA. The only observed difference in gait pattern was that patients with a revision THA had reduced hip extension at 3 months, but no differences were observed preoperatively and 12 months.

Despite the suggestions in the literature that revision THA is bound to have worse outcomes compared to primary THA, we found no differences in in patient-reported outcomes and gait patterns at 12 months postoperatively. This suggests that it may be possible, in some circumstances, for patients following revision THA to achieve similar outcomes to their peers undergoing primary THA.

Subjective outcomes used in THA show outstanding improvements in patient-reported outcomes. However, recent evidence suggests that there may be a disconnect between patient-reported and objectively measured function. The aim of this study was to investigate if physical activity and sleep patterns change from pre- to six months post primary THA.

54 patients scheduled for THA were recruited. Patients were given a wrist-worn accelerometer (GeneActiv, UK) to wear continuously for one week pre-operatively and six weeks, three months and six months post-operatively. The device was also fitted to the patient immediately following surgery to capture data for the first two post-operative weeks. The following parameters were calculated: (1) sleep efficiency; (2) the amount of time (and length of each bout and fragmentation of the activity) spent in sedentary activity; and (3) time spent in light, moderate and vigorous physical activity.

Sedentary activities showed no change in the number, duration or fragmentation (p= 0.382, 0.288, 0.382, respectively). Patients were sedentary for 5–6 bouts/day with each bout lasting 50–76 minutes/day. A significant main effect was identified for time spent in light intensity activities (p=0.049). Prior to surgery, patients spent 201 minutes/day in light intensity activity. This decreased significantly to 133 minutes/day (p=0.025) in the first two postoperative weeks before returning close to pre-operative levels (192 minutes/day) at six weeks (p=0.025). No further changes were observed in light intensity activities. A significant main effect was identified for time spent in moderate intensity activities (p=0.003). Prior to surgery, patients spent 45 minutes/day in moderate intensity activities. This dropped to 18 minutes/day in the first two postoperative weeks (p=0.190). By three months this had increased to 66 minutes/day (p=0.049). No further changes were seen. There were no significant differences in time spent in vigorous intensity activities (p=0.244). Patients spent <1minute/day in vigorous intensity activities.

Sleep efficiency did not change significantly from pre- (82%) to six months post-operative (75%) (p=0.067) − 85% is typically considered good sleep efficiency. Patients discharged to a regional hospital had significantly poorer sleep efficiency than those discharged home (mean difference=14%, p=<0.001) or to a rehabilitation centre (mean difference=15%, p=0.001).

This patient cohort didn't demonstrate an overall improvement in objectively measured physical activity patterns from pre- to six months post-operative. Sleep efficiency, did not improve and remained sub-optimal.