Circumferential allograft replacement of the proximal femur - A critical analysis

The use of proximal femoral structural allografts in revision hip arthropla sty remains controversial. The current study constitutes the mean 8.8 years followup (range, 3-12.5 Sears) of a consecutive series of 55 proximal femo ral allografts in 51 patients. In 46 patients the implant was cemented into the allograft and the distal femur, and the host proximal femur was resect ed at the time of reconstruction in all but seven patients. Five patients u nderwent revision surgery for acetabular failure, and sig additional patien ts underwent revision surgery for failure of the proximal femoral allograft , Three patients underwent successful revision surgery and had additional p roximal femoral allografts, Failure was caused by graft fracture in one pat ient, by deep infection in two patients, and by junctional nonunion in thre e patients. Junctional nonunion was seen in five patients (9%), two of whom were treated successfully with bone grafting and bone grafting and plating , respectively. Instability was observed in six patients (11%). Trochanteri c nonunion was seen in 22 patients (43%) and trochanteric escape was seen i n 14 patients (27%). The mean Harris hip score improved from 39 to 79 point s. Resorption involving the full thickness of the allograft in at least one zone was seen in seven patients. This progressed rapidly and silently with in the first 3 years but has yet to lead to the failure of any of the recon structions. Infection was ruled out in every case. Allograft resorption was seen in seven patients and may be related to a combination of factors. It is most likely that this is an immunologic problem of slow rejection, but i t is possible that the distal cement fixation led to stress shielding and r esorption attributable to mechanical disuse. The possible protective role o f retaining the bivalved host bone as a vascularized onlay autograft remain s to be clarified. Although these results justify the continued use of stru ctural allografts for selected patients, continued followup is warranted.