Morcelised Impacted Cortico-Cancellous Bone Allografts in Revision Surgery for Endoprosthetic Loosening with Osteolysis

Abstract: Revision total hip arthroplasty (RTHA) and filling of the bone defects with impacted particulated bone allograft is the concept that has been studied in this thesis. In three in vitro models, biomechanical aspects of morcelised and impacted bone allografts were studied. The recoil of an impacted graft bed (as the impaction device was released) was found to be substantial (11-34 %). The clinical implication of this is that the space for a cement mantle may disappear. The recoil was higher using smaller bone chips and using higher compaction pressure. Higher initial impaction energy was found to create a more stable graft bed, which also was the case for larger bone chips. The rotational stability for a cup cemented on an impacted graft bed was doubled when using larger chips compared to smaller. When the larger chips were defatted, the stability was doubled again. Clinical and radiological results after revision total hip arthroplasty using impaction grafting was studied for Charnley and Lubinus prosthesis after a mean follow-up 64 months. The clinical results were good for both groups. Minor subsidence of the femoral stem occurred in a few RTHA in both groups. Mechanical failure was four per cent in both groups. A surgical method for revision total knee arthroplasty with impaction grafting was demonstrated. The clinical and radiological medium term results were good. Morphological outcome in biopsies was studied from 20 patients with impaction bone grafting. One month after RTHA a fibrous stroma and some newly formed trabecular bone was found. In-growth of living bone was almost complete after 48 months. Positron Emission Tomography (PET) was used to evaluate the metabolic events taking place after impaction bone grafting. Already eight days after surgery there was a high activity inside the graft beds indicating neovascularisation and active calcium metabolism. After one year this activity had diminished.

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