[Is GSB knee prosthesis implantation for patellar problems still justifiable? Experiences and results based on 230 implanted GSB knee joint prostheses].

In our clinical the GSB-prosthesis has proved to be a good therapeutic concept. In 1988 we controlled 230 patients who had got GSB-prostheses in the years 1979-1987. The average age of our patients was 75 years. Most times surgery had been done because of idiopathic osteoarthrosis, rarely because of post-traumatic or rheumatoid arthritis. Indications for surgery were usually severe pain, limited range of movement and deformities of the knee joint. In the beginning of the studied period we had implanted GSB-type I-prostheses, later we had implanted GSB-type II-prostheses with or without femoropatellar surface. We achieved good results in pain reduction and in range of movement. However the major complications were caused by the patella. These patients had problems at climbing stairs, pain at the beginning of movements and at getting up from chairs. They presented with increased pain sensitivity at the tip of the patella and to friction of the patella. Regular radiological findings were severe destructions or fractures of the upper patellar pole. These problems led in 40 cases (17% of our cases) to reoperations until 1988 (At all we reoperated 50 times because some patients needed additional reoperations). According to our studies results there will be a need for reoperations in about 50 other cases. We discuss the following reasons for this high rate of severe patellar complications demanding re-surgery: 1. Localisation of the patella: according to our studies the patella is frequently dranged cranially, seldom laterally. 2. Often we found an internal rotation of the tibia against the femur.(ABSTRACT TRUNCATED AT 250 WORDS)