Trajectories in functional recovery for patients receiving inpatient rehabilitation for unilateral hip or knee replacement

The purpose of this study was to explore trajectories of recovery in patients with lower extremity joint replacements receiving post-acute rehabilitation. A retrospective cohort design was used to examine data from the Uniform Data System for Medical Rehabilitation (UDSMR^®) for 7434 patients with total knee replacement (TKR) and 4765 patients with total hip replacement (THR) who received rehabilitation from 2008 to 2010. Functional Independence Measure (FIM)™ instrument ratings were obtained at admission, discharge, and 80-180 days after discharge. Random coefficient regression analyses using linear mixed models were used to estimate mean ratings for items within the four motor subscales (self-care, sphincter control, transfers, and locomotion) and the cognitive domain of the FIM instrument. Mean improvements at discharge for motor items ranged from 1.16 (95% confidence interval [CI]: 1.14, 1.19) to 2.69 (95% CI: 2.66, 2.71) points for sphincter control and locomotion, respectively. At follow-up mean motor improvements ranged from 2.17 (95% CI: 2.15, 2.20) to 4.06 (95% CI: 4.03, 4.06) points for sphincter control and locomotion, respectively. FIM cognition yielded smaller improvements: discharge=0.47 (95% CI: 0.46, 0.48); follow-up=0.83 (95% CI: 0.81, 0.84). Persons who were younger, female, non-Hispanic white, unmarried, with fewer comorbid conditions, and who received a TKR demonstrated slightly higher functional motor ratings. Overall, patients with unilateral knee or hip replacement experienced substantial improvement in motor functioning both during and up to six months following inpatient rehabilitation.