Abstract
Introduction
The reconstructive hip surgeon is commonly faced with complex cases where severe bone loss makes conventional revision techniques difficult or impossible. This problem is likely to increase in future, as there is a good correlation between the degree of bone loss seen and number of previous total hip operations. In such situations, one alternative is the use impaction allografting with cement. This has captured the attention of the orthopaedic community because of its potential for reconstituting femoral bone stock.
History
The first clinical reports of impaction allografting on the femoral side were in relation to revision with cementless stems. The use of morselised bone with cement on the femoral side was first reported by the Exeter group.
Biology
The great enthusiasm with which this technique has been received is related to its biological potential to increase bone stock. The rapid revascularization, incorporation and remodelling of morselised compacted cancellous allograft differs dramatically from structural allografting where bone ingrowth usually is limited to 2–3 mm. Histological evidence for bony reconstitution has been presented from postmortem retrievals, and from biopsies at the time of trochanteric wire removal.
Impaction allografting, performed with great attention to detail using appropriate equipment, represents an exciting reconstructive solution for contained femoral defects. Its role in larger and combined defects remains open to scrutiny.
A number of technical issues with regards to allograft preparation and prosthetic design have been resolved over the past decade. The necessary intra-operative precautions are now appreciated, and the high complication rates seen in some centers have been explained in simple terms. Careful observation and cautious optimism are necessary as further refinements may well improve the predictability of the clinical results and expand the indications for this important addition to the armamentarium of the revision surgeon.
The technique of impaction allografting of the femur has great potential, and is here to stay as a reconstructive solution to the deficient proximal femur in revision hip arthroplasty. Although many questions remain unanswered, the capacity for impaction allografting to act as a truly biologic augmentation of the proximal femur makes this technique the modern bridge from revision arthroplasty to reconstructive hip surgery.
