Background:
A comprehensive geriatric assessment (CGA) is considered the gold standard for improving numerous relevant endpoints for older people in hospitals. The aim of the study was to investigate what happens across time to individual test components of a CGA after completion of inpatient rehabilitation and 3 months after surgery compared to the start of rehabilitation in orthogeriatric patients who underwent elective total hip or knee arthroplasty (THA or TKA).

Methods:
In this prospective study, we used data from 186 participants (THA n = 110, TKA n = 76) of the Special Orthopaedic Geriatrics (SOG) trial, funded by the German Federal Joint Committee (GBA). Study data were collected preoperatively (basic information), on admission to inpatient rehabilitation (7th postoperative day), on discharge (4 weeks postoperatively) and 3 months after THA or TKA. Non-parametric Wilcoxon signed rank tests were used for the main statistical analyses, and Mann-Whitney U tests were employed for secondary analysis stratified by age, frailty, and mobility.

Results:
Compared to admission, both surgical groups showed significant improvements in Barthel Index, Nutritional Risk Screening (NRS), frailty, Short Physical Performance Battery (SPPB), gait speed and reduction in polypharmacy on discharge from inpatient rehabilitation (effect size, 0.18–0.79). 3 months postoperatively, there were further significant improvements in Barthel Index, SPPB, gait speed and reduction in polypharmacy in both groups compared to discharge from rehabilitation (effect size, 0,38 − 0,75), while NRS and frailty only improved in the THA group. Differentiated according to the presence of frailty (Fried’s frailty criteria ≥ 3), both groups demonstrated significantly better improvements in frail participants than in robust or pre-frail patients.

Conclusion:
The results of this study reveal that key components of CGA significantly improve in orthogeriatric patients after THA and TKA three weeks after inpatient rehabilitation and continue to improve up to three months after surgery. There is evidence that obviously frail patients benefit particularly well from rehabilitation programmes.