Treatment options of bone defects in revision of total knee replacement

UNLABELLED: Total condylar knee replacement presently has more than 10 years of history in Hungary. Besides a large number of routine primary implantations, the number of exchange arthroplasties performed due to aseptic loosening is continuously growing as well. One of the most significant difficulties of revision interventions is the management of bone defects. OBJECTIVE: Aim of present study is to describe the treatment options of bone deficiencies found during knee arthroplasties. Indication criteria of different methods are introduced together with the results of revision operations dealing with bone defects in the authors' patient sample. METHOD: Between 1995 and 2001, 35 revision total knee replacements have been performed at the authors' institute where significant bone defects had to be dealt with. Because of aseptic loosening, unior bicondylar implant revision has been carried out in 24 cases and total condylar prosthesis revision in 11 cases. With 14 patients autologous bone, in 7 cases allogenic cancellous bone and in two cases structural allografts have been used. Metal augmentation of the prosthesis in itself was applied in 4 patients, in 8 further patients in combination with bone grafts. RESULTS: During physical and radiological control examination of 31 knees in average 3 years after the operation, authors found good clinical results in all cases except one. Bone grafts showed good remodeling, and the implants were all fixed well on the control radiographs except of the one failed case. With this patient, collapse of the structural allograft used for reconstruction of a large medial tibial defect was evident and the tibial component became loose. CONCLUSIONS: Based on international literature data and their own experiences, authors conclude that aseptic loosening of total knee endoprostheses can be managed with good results even if it is combined with massive bone loss. For a successful revision, an appropriate technical background, personal skills and a well-functioning bone bank is unavoidable. For the management of tibial defects, authors highly recommend the usage of long stem extensions.