This is a retrospective, multicenter case series with a prospective follow-up to confirm the safety and performance of the Gemini SL Fixed Bearing knee prosthesis in midterm follow-up under routine conditions. Primary outcome of the study is the 5-year survival rate of the Gemini SL Fixed Bearing knee prosthesis with revision for any reason as the end point.

Sufficient data (e.g. biomechanical tests, biocompatibility, vigilance data and results of risk management, clinical data of comparable devices) are available for assessing the safety and performance of the Gemini SL knee prosthesis system. Unfortunately, no data are available for the Gemini SL Fixed Bearing knee prosthesis. As one part of the post market surveillance (PMS) system of the sponsor, the clinical outcome of the Gemini SL Fixed Bearing knee prosthesis in the midterm follow-up shall be evaluated. Therefore patients who received a Gemini Sl Fixed bearing knee prosthesis 3 years ago are invited to participate in follow-up examinations.

Inclusion Criteria:

• Implantation of a Gemini SL Fixed Bearing knee prostheses 3 years ago
• Age between 18 and 75 years at the time of implantation

Exclusion Criteria:

• Body Mass Index (BMI) > 40 kg/m² at the time of implantation
• Comorbidities and known medical circumstances which would affect the clinical functional outcome after implantation of the knee prosthesis (e.g. neurological or musculoskeletal diseases) at the time of implantation
• Prisoner

All patients received a Gemini SL Fixed Bearing knee prosthesis in the study sites 3 years ago are possible participants of the study. Hospital charts will be screened in order to identify these candidates. The patients will be followed up at 3-year interval.