Risk of complications associated with prolonged post-operative hospitalization and postoperative outcomes in elderly patients with high BMI undergoing elective total knee arthroplasty

The primary aim of our investigation is to conduct a detailed, stratified, and controlled examination concerning the body mass index (BMI) of elderly individuals who have undergone total knee arthroplasty (TKA). Based on preoperative BMIs, 135 knees (37 men and 98 women, 75 years or older) were categorized into normal-weight (n = 41), overweight (n = 49), and obese (n = 45) groups. The duration of follow-up was 32.86 ± 11.73 (range 17–58 ) months. Assessment indicators included changes in hemoglobin (ΔHb) and hematocrit (ΔHCT) before and after surgery, operation time, and post-operative hospital stays. Follow-up metrics included range of motion (ROM), Oxford knee score (OKS), visual analogue scale (VAS), and postoperative complications. This study was reported in compliance with the STROBE checklist for reporting observational studies (Supplementary File S1). No significant differences were observed in ΔHb and ΔHCT before and after surgery, as well as operation time (p > 0.05) across the groups. The elderly obese group, however, exhibited longer hospital stays after surgery and lower ROM compared to normal-weight and overweight groups (p = 0.000). Up to the last follow-up, no notable differences were found in VAS (p = 0.198), and OKS (p = 0.696) among the three groups. Compared to preoperative, a significant improvement was noted in ROM, OKS, and VAS across all groups (p < 0.001). The complication rates showed no significant disparity among the groups (p > 0.05). In elderly obese patients treated by TKA, despite increased postoperative hospital stays, the rates of early infection, poor wound healing, and thromboembolic complications remained low and were not significantly different from those in the normal-weight group. Meanwhile, postoperative knee mobility is poorer in elderly obese patients, and the perioperative management of this special group should be fully considered by the operator.