Mid- to long-term complications and outcome for morbidly obese patients after total knee arthroplasty: a systematic review and meta-analysis

Abstract

Purpose Due to substantial increase in obesity, the demand for total knee arthroplasty (TKA) in obese and morbidly obese patients is higher than ever. This review aims to investigate mid- to long-term complications, revision rates, and outcome for morbidly obese, compared with non-obese after TKA. Methods A systematic search was conducted in May 2021. Included studies reported revision rates for morbidly obese and non-obese with a mean follow-up of at least 2 years. Reported knee society score (KSS) has been used to compare the functional outcome. PRISMA protocol was followed, and PROSPERO registered (ID: CRD42021254119). Results From 12 studies that met the inclusion criteria, a total of 1031 cases of morbidly obese and 9797 cases of non-obese controls were included. The risk ratio for revision was 1.48 for the morbidly obese, compared with non-obese (95% CI: 0.98 to 2.24; P = 0.06). Regarding aseptic and septic revision, the risk ratio was 1.44 (95% CI: 0.64 to 3.25; P  = 0.37) and 2.22 (95% CI: 0.89 to 5.57; P  = 0.09), respectively. The morbidly obese scored lower in Objective Knee Society Score (OKSS) and Functional Knee Society Score (FKSS) both preoperatively and postoperatively, compared with the non-obese; however, the two groups improved equally in function scores OKSS (P= 0.967) and FKSS (P  = 0.834). Overall risk ratio for complications was 1.56 (95% CI: 0.98 to 2.48; P  = 0.06). Conclusions The gained benefit in functional outcome surpasses the increase in risk of revision and complications for the morbidly obese in TKA surgery.