[Long-term analysis of cement-free implanted PCA knee endoprostheses with 5-8 year follow-up]

A total of 54 PCA knee-joint endoprostheses were followed up over a period of 5-8 years. All the uncemented implants (52 femoral components, 52 patellar components, 54 tibial components) were subjected to radiological analysis of the anchorage zone between prosthesis and bone. The results were evaluated on the basis of the postoperative radiographs and the follow-up radiographs, which were divided into four groups. It was necessary to create a 5th group for radiographs not suitable for evaluation. The use of fluoroscopy is therefore essential in order to ensure that all radiographs can be evaluated. The best results were obtained with the uncemented femoral prosthesis. Complete "incorporation" with close contact between prosthesis and bone was observed in all cases, even if implantation was not optimal. Radiological loosening of the uncemented patella occurred in 3 patients, and it was necessary to perform one patellectomy 6 years postoperatively. In the case of the tibia implant, the follow-up showed radiological "incorporation" of the prosthesis in all cases with technically adequate implantation: the tibia implant was inadequately implanted in 8 cases. Radiological loosening of the tibia implant was observed in 4 of these 8 patients. There was a higher rate of radiological failure in the group of patients over 70 years of age, and among patients whose primary disease was primary chronic polyarthritis. However, given technically exact implantation, satisfactory results could be obtained even in these two groups. Clinical pains occurred only several years after evidence of radiological loosening. Radiological follow-up analysis therefore offers a means of obtaining early information about the prosthesis-bone interface of uncemented total knee-joint endoprosthesis.