Background Knee arthroplasty is one of the most frequently performed operations in Germany, with approximately 170000 procedures per year. It is therefore essential that physicians should adhere to an appropriate, and patient-centered indication process. The updated guideline indication criteria for knee arthroplasty (EKIT-Knee) contain recommendations, which are based on current evidence and agreed upon by a broad consensus panel. For practical use, the checklist has also been updated. Methods For this guideline update, a systematic literature research was conducted in order to analyse (inter-)national guidelines and systematic reviews focusing on osteoarthritis of the knee and knee arthroplasty, to answer clinically relevant questions on diagnostic, predictors of outcome, risk factors and contraindications. Results Knee arthroplasty should solely be performed in patients with radiologically proven moderate or severe osteoarthritis of the knee (Kellgren-Lawrence grade 3 or 4), after previous non-surgical treatment for at least three months, in patients with high subjective burden with regard to knee-related complaints and after exclusion of possible contraindications (infection, comorbidities, BMI 40 kg/m2). Modifiable risk factors (such as smoking, diabetes mellitus, anaemia) should be addressed and optimised in advance. After meeting current guideline indications, a shared decision-making process between patients and surgeons is recommended, in order to maintain high quality surgical management of patients with osteoarthritis of the knee. Conclusions The update of the S2k guideline was expanded to include unicondylar knee arthroplasty, the preoperative optimisation of modifiable risk factors was added and the main indication criteria were specified.