Dirk Müller, Holger Haas, Hartmut Bork, Johannes Flechtenmacher, Andreas M. Halder, Karl-Dieter Heller, Bernd Kladny, Jörg Lützner, Wolfram Mittelmeier, Carsten Perka, A. Pingsmann, Maximilian Rudert, Arnd Steinbrück, Dieter Christian Wirtz, Amelie Flothow, Leonie Sundmacher, I Lazic, Rüdiger von Eisenhart-Rothe
BACKGROUND: Valid risk adjustment is a prerequisite in knee arthroplasty to enable fair comparisons of treatment quality across hospitals and surgeons. Existing models mainly consider patient-related factors such as age or comorbidities. Consensus on joint-specific risk factors for postoperative complications is currently lacking. OBJECTIVES: The aim of this study was to establish expert consensus on clinically relevant joint-specific risk factors in total knee arthroplasty (TKA). METHODS: A three-stage modified Delphi process was conducted with 14 German experts in the field of TKA. Based on a systematic literature search, 120 potential risk factors were identified. In the first round, all factors were rated; in the second round, the focus was narrowed to 70 joint-specific factors. In a final virtual consensus meeting (third round), the most relevant factors were refined and prioritized. RESULTS: Twelve joint-specific risk factors were identified and ranked: prior septic surgery, large bone defects, implanted foreign material, valgus malalignment > 10°, varus malalignment > 15°, extension deficit > 10°, flexion < 70°, Kellgren-Lawrence score < 3°, patella baja, prior bone surgery, genu recurvatum > 10°, and prior ligament reconstruction. CONCLUSIONS: Through a structured Delphi consensus process, 12 joint-specific risk factors were defined by a panel of German arthroplasty experts. These factors may meaningfully complement existing risk adjustment models. Future research should evaluate their predictive validity and integration into routine registries (e.g., EPRD) as well as quality assurance instruments.