Clinical and Functional Outcome of the GEMINI SL Fixed Bearing PS Knee Prosthesis

Primary outcome of the study is the 10-year survival rate of the Gemini SL Fixed Bearing PS knee prosthesis with revision for any reason as the endpoint. Revisions are defined as removal, exchange or adding of any implant components. The definition does not include subsequent implantations or exchange of the patella component or the polyethylene plateau. Survival rate will be calculated according to the method of Kaplan-Meier.

Survival rate of the GEMINI SL Fixed Bearing PS knee prosthesis after 6 months, 1, 3 and 5 years

Evaluation of the change in functional and clinical outcome from preoperative to 6 months, 1, 3, 5 and 10 years postoperative, measured by the Knee injury and Osteoarthritis Outcome Score (KOOS). The KOOS is a reliable and validated knee-specific patient-administered outcome instrument. The previous week is taken into consideration when answering the questions. Standardized answer options are given (5 Likert boxes) and each question gets a score from 0 (best result) to 4 (worst result). The KOOS consists of 5 sub-scales: Pain, Symptoms, Function in daily living (ADL), Function in sport and recreation (Sport/Rec) and Hip/Knee related Quality of life (QoL). A normalized score (100 indicating no symptoms and 0 indicating extreme symptoms) is calculated for each subscale.

Evaluation of the change in functional and clinical outcome from preoperative to 6 months, 1, 3, 5 and 10 years postoperative, measured by the Knee Society Score (KSS). The KSS is a frequently used, reliable and validated score in the assessment of a subject's knee pain and functional knee capacity. It comprises two arms, the functional ability and the clinical examination score, each ranging from 0 points (worst result) to 100 points (best result).

Complications related to implantation of the GEMINI SL Fixed Bearing PS knee prosthesis (infections, dislocations, migrations, aseptic loosenings, periprosthetic fractures, intra-operative fractures, implant fractures, soft tissue fractures, joint instability etc.) will be recorded at all follow-up examinations.

All subsequent surgical interventions at the operated knee (exchange of the polyethylene plateau, additional implantation/exchange of the patella component, soft-tissue balancing, debridement etc) will be recorded at all follow-up examinations.