To Örebro University

Osteoarthritis (OA) is the most common disorder of the joint, affecting over 500million people globally, and is one of the most demanding disabilities worldwide.One of the most prominent risk factors for developing OA is obesity. Clinically, the most common site of OA is the knee. Obesity has been associated with worseoutcomes after Total Knee Arthroplasty (TKA) and patients with obesity have beenshown to have an increased risk of revision after TKA. Obesity is further associatedwith several comorbidities as well as psychological problems, including depression and low self-esteem. Treatment of obesity using lifestyle modifications often results in insufficient weight loss. The most effective method of achieving weight loss in patients with obesity and counteracting morbid obesity with its relatedcomorbidities is Bariatric Surgery (BS). Consequently, BS before TKA may reduce the risk of revision after TKA. Thus, this thesis evaluates risk of revision, pain,Activity in Daily Life function (ADL), and weight change after TKA in patients with prior BS compared to patients without prior BS. Additionally, the thesis aims toidentify the criteria and practices used by Swedish centers and knee arthroplasty surgeons when performing knee arthroplasty in patients who have obesity. Data were extracted from the Swedish Knee Arthroplasty Registry and Scandinavian Obesity Registry to identify patients with BS and TKA in Papers I–III. In Paper IV, a survey was created and sent to all the Swedish centers performing knee arthroplasty.

No benefit in risk of revision for all reasons or in outcome regarding pain and ADL after TKA were found in patients with prior BS compared to patients without prior BS. This was also seen when comparing to patients with BS following TKA for riskof revision for all reasons. However, when adjusting for Body Mass Index (BMI) prior to TKA, the risk of revision due to suspected or verified infection was higher in patients with BS prior to TKA than in patients without BS. Additionally, no statistically significant difference in 1-year or 2-years postoperative weight change depending on the sequence of surgery was found. Paper IV indicated that most knee arthroplasty surgeons in Sweden inform their patients with obesity regarding risksof knee arthroplasty. Furthermore, most centers that perform knee arthroplasties inSweden have an upper BMI limit.