Long-term outcome of total knee arthroplasty in patients with morbid obesity

Abstract

Introduction: Patients with morbid obesity and advanced painful knee osteoarthritis are considered as poor candidates for total knee replacement. Our aims were to evaluate the outcomes of TKR surgery and the risks for post-operative complications in patients with morbid obesity (BMI > 40 kg/m²) as compared with obese patients (30 < BMI ≤ 40 kg/m²) and non-obese patients, BMI < 30 kg/m²); to evaluate if there are differences between morbid-obese patients (BMI 40-49.99 kg/m²) and extreme morbid obese patients (BMI > 50 kg/m²); and to present some surgical tips which can improve the TKR outcomes in morbid obese patients.

Materials and methods: There were successive 333 patients, of them 39 patients (11.7%) were lost for follow-up. So, this series included 292 patients - 82 with bilateral TKR- and 374 TKR. The mean age was 64.3 years old (48-83 years) and the mean follow-up 10.8 years (4-17 years). The KSS and FKSS scores were calculated at the end of the follow-up period and compared to the pre-operative evaluation. Radiographic assessment at the end of follow-up included evaluation of implant position, alignment, and presence of radiolucent lines around the implants and was compared with the immediate post-operative radiographs. Statistical analysis was performed using SPSS v 22.0.

Results: Our findings showed marked improvement following TKR of non-obese, obese, and morbid obese patients, regarding the KSS and FKSS. Significant change was observed between the non-obese and obese patients as compared to morbid obese patients. There were no significant differences between morbid obese patients with BMI > 40 versus those with BMI > 50. There was a slight increased risk of early complications following TKR in morbid obese patients such as skin necrosis and infection around the surgical incision.

Conclusions: Marked improvement was observed in the three groups of patients after TKR, although non-obese and obese groups had better mean scores of KSS and FKSS than morbid obese patients. No significant differences were found within the morbid obese patients themselves. Therefore, we believe that morbid obese patients are appropriate candidates and can enjoy the benefits of total knee arthroplasty done with careful use of some surgical tips presented in our study.

Keywords: Knee; Morbid obesity; Obesity; Osteoarthritis; Total knee arthroplasty; Total knee replacement.