Background <p>In the year 2022, more than 300,000 total hip and knee primary arthroplasties were recorded in the German Arthroplasty Registry. The ever-increasing number of interventions naturally leads to an increase in the absolute number of possible complications. The abundance of internationally available data makes it possible to determine risk factors for postoperative complications.</p> Risk factors <p>Professional societies involved in the German guidelines in the field of orthopedics place great emphasis on modifiable risk factors, as their adequate management can consequently reduce the likelihood of postoperative complications. One of the most common modifiable risk factors is obesity, with its prevalence remaining consistently high in most developed countries. In the field of orthopedics, the Association of the Scientific Medical Societies in Germany focuses on modifiable risk factors including obesity, diabetes mellitus and smoking.</p> Obesity <p>In the case of obesity in particular, the guidelines for knee and hip arthroplasty recommend a&#xa0;weight loss attempt for patients with a&#xa0;BMI &gt; 30 kg/m². A&#xa0;BMI ≥ 40 kg/m² is considered a&#xa0;“relative contraindication” in the guidelines. Shared decision making is emphasized in both guidelines. Ultimately, the particularly critical individual assessment of risk and benefit for each obese patient remains crucial for the final decision.</p>