The interfacial membrane between bone and implant has been shown to be a key tissue in the process of aseptic loosening of total hip arthroplasty. The cells within the interfacial membrane produce numerous inflammatory mediators which, through complex mechanisms, cause periprosthetic osteolysis and aseptic loosening. Both epidermal growth factor (EGF) and transforming growth factor alpha (TGFalpha) have similar biological functions. They have been found to stimulate bone resorption.
To investigate the presence, cellular localisation, and extent of expression of EGF and TGFalpha in interfacial membrane retrieved from revision total hip arthroplasty and compare it with that in synovial membrane from primary total hip arthroplasty.
Ten interfacial membranes and 10 synovial membranes were stained with avidin-biotin-peroxidase complex for EGF and TGFalpha. The staining process was done using the Lab Vision Autostainer. The results were measured by a semiautomatic VIDAS image analysis system.
Immunoreactivity for both EGF and TGFalpha was found in the endothelial cells of blood vessels, macrophages, and fibroblasts, both in interfacial membranes and synovial membranes. However, the number of EGF (980 (370)) and TGFalpha (1070 (360)) positive cells per mm(2) was greater in interfacial membranes than in the synovial membranes (220 (200), 270 (100); p<0.01).
It is suggested that owing to their increased expression in interfacial membrane, EGF and TGFalpha may have an important pathogenetic role in stimulating periprosthetic bone resorption in aseptic loosening of total hip arthroplasty.