Pro-inflammatory and anti-inflammatory circulating cytokines and periprosthetic osteolysis.

We investigated the circulating levels of the main cytokines involved in bone resorption (IL-1beta, IL-6, TNF-alpha), prostaglandins (PGE2) and metalloproteases (MMP-1), as possible early markers of osteolysis, in the serum of eight patients with periprosthetic osteolysis and ten patients without osteolysis. All had received a cementless hip prosthesis (ABG-1). We also assessed the serum levels of IL-1 and TGF-beta anti-inflammatory cytokines exerting protective effect on bone resorption. The mean serum levels of IL-1beta, IL-6, TNF-alpha, TGF-beta, MMP-1, and PGE2 in patients with periprosthetic osteolysis did not differ significantly from those of patients without osteolysis or from those of normal controls. IL-11 serum levels were not detectable at all in any of the patients, while they were detected within normal reference values in the control subjects (significant inverse correlation). We believe that circulating cytokines cannot be regarded as markers of osteolysis, a condition characterised by a local inflammation without systemic signs of inflammation. On the contrary, the undetectable levels of IL-11 in implanted patients could provide evidence for a lack of balance between pro- and anti-inflammatory cytokines in these patients.

Increase in free radicals on UHMWPE hip prostheses components due to inflamed synovial cell products.

Oxidative degradation of artificial UHMWPE joint implants caused by gamma-ray sterilization is thought to be responsible for the production of wear debris resulting in adverse tissue responses. On the other hand, it is well known that inflammation is associated with generation, by inflammatory cells, of free radicals (H(2)O(2) and NO) and destructive proteolytic enzymes (collagenases), which creates a strong oxidative environment. We hypothesized that when an UHMWPE implantation was performed in an inflammatory joint environment, the oxidative substances produced by inflamed synoviocytes could increase oxidative degradation of the polyethylene insert. We measured the amount of free radicals on conventional and on Duration-treated polyethylene samples by the electron spin resonance (ESR) technique before and after exposure of the samples to (1) inflamed synovial cell cultures; (2) normal synovial cell cultures; and (3) medium alone. We observed an increase in the number of free radicals on polyethylene samples after their immersion in cell cultures. Furthermore, it was observed that the increase of free radicals on polyethylene correlated with the degree of inflammation of synovial cells in culture.

The use of hydroxyapatite-coated implants in revision surgery for acetubular component loosening.

Since 1989,the authors have used the Hydroxyapatite (HA)-coated ABG prosthesis for both primary and revision hip replacement. Hydroxyapatite is osteoconductive, and therefore speeds up bone formation and ensures a direct contact between the implant and the host bone, without any interposed fibrous tissue. The cup can thus be firmly fixed in the bony acetabulum, with eventual osseointegration into the host bone. The quality of the results achieved, at primary hip replacement, with bioactively coated devices has been highlighted in a large number of publications.