Background The length of hospital stay (LOS) has become a valuable outcome measure of any operation, and it also directly impacts hospital cost.

Objectives To identify risk factors for LOS after total knee arthroplasty (TKA) in rheumatoid arthritis (RA) and osteoarthritis (OA) patients.

Methods We evaluated 259 (RA, 29; OA, 230) patients undergoing TKA at our hospital from July 2012 to August 2014. The RA patients group had a mean age of 70 years and included 22 females and 7 males. The OA patients group included 188 females and 42 males with a mean age of 75 years. Data collected included LOS, gender, age, body mass index (BMI), use of anti-platelet agents, operative time, use of cement for TKA, postoperative estimated blood loss and postoperative deep vein thrombosis (DVT). The diagnosis of DVT was based on ultrasonography. Multiple linear regression analysis was performed to identify variables predictive of prolonged LOS. LOS and operative time of RA and OA patients were compared using the Mann–Whitney U-test.

Results The results of the multiple linear regression analysis indicated that age (P<0.001) and operative time (P=0.003) were risk factors for prolonged LOS. A sub-analysis of operative time revealed that male gender (P<0.001), BMI (P=0.046) and the use of cement for TKA (P=0.009) were associated with longer operative time. Of the patients undergoing TKA, the median LOS was 26 (RA, 26; OA, 26) days and the median operative time was 73 (RA, 72; OA, 74) minutes. There were no statistically significant differences between RA and OA patients.

Conclusions We identified that elderly patients and longer operative time are associated with increased LOS among RA and OA patients undergoing TKA, and male gender, higher BMI and the use of cement for TKA are risk factors for longer operative time. There is a need to increase knowledge on the risk factors of longer LOS to reduce total hospital costs.

Disclosure of Interest None declared