Purpose: There are two problems using structural allografts in revision total hip surgery. The long-term stability of bulk allografts and the intraoperative primary stability of the graft and implant limit the success of this revision philosophy. The purpose of this study was to analyse the reasons of early loosening of cementless cups after reconstruction with bulk allografts.
Method: In a retrospective study 78 revisions were analysed radiologically. The preoperative stage of bone destruction, the size of allografts, the implant-allograft coverage, and the position of implants were analysed in X-ray series.
Result: There were 12 (15.3%) cases with aseptic and 5 (6%) cases with septic cup loosening, after revision surgery, with an average follow-up of 37 (25-84) months. All of these failures were registered in the first 12 months postoperatively. Large bone defects and an implant-allograft coverage of more than 50% are significant (p < 0.001) risk factors of early aseptic loosening.
Conclusions: It is important to give careful attentions to primary stability, especially in revision total hip arthroplasty using structural allografts and cementless cups. For primary stability as well as secondary stability a stable fixation with as large as possible areas of contact between implant and living bone is necessary. The limit of the method (allograft and cementless cup) is to be seen in stage 2B according Paprosky (1990). In larger defects alternative reconstruction methods have to be used.