Osteonecrosis of the femoral head is a destructive joint disease requiring early hip arthroplasty. The polyethylene-metal design using a 22-mm femoral head component, introduced by Charnley in 1950, has been widely used for over half a century. Since then, different materials with the capacity to minimize friction between bearing surfaces and various cement or cementless insert fixations have been developed. Although the outcome of second and third generation designs using better bearing materials and technologies has been favorable, less favorable results are seen with total hip arthroplasty in young patients with osteonecrosis. Selection of appropriate materials for hip arthroplasty is important for any potential revisions that might become inevitable due to the limited durability of a prosthetic hip joint. Alternative hip arthroplasties, which include hemiresurfacing arthroplasty and bipolar hemiarthroplasty, have not been found to have acceptable outcomes. Metal-on-metal resurfacing has recently been suggested as a feasible option for young patients with extra physical demands; however, concerns about complications such as hypersensitivity reaction or pseudotumor formation on metal bearings have emerged. To ensure successful long-term outcomes in hip arthroplasty, factors such as insert stabilization and surfaces with less friction are essential. Understanding these aspects in arthroplasty is important to selection of proper materials and to making appropriate decisions for patients with osteonecrosis of the femoral head.
Arthroplasty* ; Arthroplasty, Replacement, Hip ; Friction ; Head* ; Hemiarthroplasty ; Hip ; Hip Joint ; Humans ; Hypersensitivity ; Joint Diseases ; Osteonecrosis*

STUDY DESIGN: An experimental animal study. OBJECTIVES: To create a more appropriate disc degeneration model which shows how Interleukin 1alpha may induce the activation of metalloproteinases within the nucleus pulposus. SUMMARY OF LITERATURE REVIEW: There are few disc degeneration models wherein there is activation of metalloproteinases within the nucleus pulposus without structural destruction of the intervertebral disc. MATERIALS AND METHODS: Three consecutive intervertebral discs in New Zealand White Rabbits were exposed. Each disc was injected with 0.1ml of saline (Saline group), 0.1ml of 1microg/ml (IL-1 group), 0.1ml of 10microg/ml (IL-10 group) of IL-1alpha through a 30-gauge needle. The lumbar spine was harvested 12 weeks after operation. We then analyzed radiographic findings and histological changes. RESULTS: There was no difference in the radiological disc height index among the three groups; 0.071 in saline group, 0.045 in IL-1 group and 0.058 in IL-10 group (p=0.194). The histological cellularity of the nucleus pulposus revealed a decrease in the number of cells (p=0.0001, 1.42 in saline group vs. 3.00 in IL-10 group; p=0.001, 2.00 in IL-1 group and 3.00 in IL-10). The histological matrix of the nucleus pulposus was 1.42 in saline group and 2.42 in IL-10(p=0.007), which meant that there had been condensation of the extracellular nucleus pulposus matrix. CONCLUSIONS: The results of this study demonstrate that interleukin-1alpha may contribute to degradation of the nucleus pulposus. This is useful for future study into the effects of the cytokine inhibitor on matrix regeneration and cellularity in the nucleus pulposus in intervertebral disc disease.
Animals ; European Continental Ancestry Group ; Humans ; Interleukin-1 ; Interleukin-10 ; Interleukin-1alpha ; Intervertebral Disc ; Intervertebral Disc Degeneration ; Intervertebral Disc Displacement ; Metalloproteases ; Needles ; Rabbits ; Regeneration ; Spine