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.