Abstract
Aim: To examine the histology of the bone-cement interface in a canine total hip model comparing two different cementing techniques.
Method: Seven adult mongrel dogs underwent staged bilateral total hip replacement. On one side the cement was packed into the femur with a finger while on the opposite side the femoral canal was washed, brushed, distally plugged and injected with cement under pressure before inserting the femoral component. Sequential fluorochrome bone labelling was performed. The dogs were sacrificed up to six months after the surgery. Undecalcified sections of the femur were examined by fluorescent microscopy.
Results: Post-operative radiographs showed complete filling of the proximal femur with cement in the pressure injected group, and a relatively thin mantle in the finger-packed group. Histology of the finger-packed group showed minimal intrusion of cement into the cancellous bed, direct apposition of cement and bone with small areas of fibrous tissue interposition. In the pressure- injected group the cement extended to the endosteal cortex, there was no bone necrosis, and the intruded bone underwent remodelling similar to that at the margins.
Conclusions: This study suggested that ‘third generation’ cementing techniques result in greater contact between bone and cement, and may explain the claim that femoral stems in humans inserted using third generation techniques are more durable than those inserted using ‘first generation’ techniques.
The abstracts were prepared by Professor Alan Thurston. Correspondence should be addressed to him at the New Zealand Orthopaedic Association, PO Box 7451, Wellington, New Zealand.
