Abstract
The surgeon’s dilemma when faced with bone loss during hip replacement surgery is to try and leave more bone than he finds and risk the complications of bone grafting or use more cement or a bigger prosthesis and postpone and complicate later reconstructions.
It is however a fact that good cement or prosthesis build up is better than a bad allograft. Types of allograft include bulk allograft, small fragment allograft and demineralized bone matrix. The author had in recent years done more and more mixed allografts in combination with bone graft substitutes and the present favourite is calcium sulphate pellets. Slooff believes that fresh frozen small fragments are the best, but in South Africa allografts are gamma radiated and although fears existed that gamma radiation could be detrimental to the biological response 2.5MRad dose seems to eliminate risk of infection and keep its biological properties. One of the arguments against bulk allograft is the slow and superficial incorporation and the risk of late collapse.
More recently immunological response as a factor in a late failure has come to the fore. Clinical experience of up to 22 year follow up with these various types of bone grafts is discussed and representative cases shown. Where morsellized bone is used in combination with a supporting ring of cages or pressfit cups it is important that 50% of host bone contact with the metal is achieved and allograft filling up the rest as the prosthesis or cage resting on an allograft can easily fail when compression of the allograft occurring during weight bearing. Femoral struct grafts are used, where the concave side is filled with the mixed allograft and makes excellent biological plates when femoral shaft defects or peri-prosthetic fractures are treated, and full incorporation takes place.
In conclusion allografts are very useful in hip revision surgery provided certain principles are adhered to.
Correspondence should be addressed to: Léana Fourie, CEO SAOA, PO Box 12918, Brandhof 9324 South Africa.
