Ectopic bone formation after treatment with colchicine.

We followed changes occurring within bone tissue and marrow cells during the process of colchicine-induced ectopic bone development and its resorption inside the marrow cavity of the rat tibia. To stimulate ectopic bone formation male Wistar rats were i.p injected with 0.5 or 1 mg/kg b.w. of colchicine or with a 100 microg intra-bone injection. Not all subjects responded to colchicine with ectopic bone formation in the marrow cavity, even among individuals belonging to the same strain. The kind ofresponse in a given animal depended on the dose and site of colchicine administration. During 10 days of the experiment an increase in the occurrence of micronuclei in the polychromatic erythrocytes residing in the bone marrow (even 40-fold) was observed, indicating high genotoxicity of colchicine (at a dose of 1 mg/kg b.w. i.p. or 100 microg intra-bone injection). An increase in the frequency of emperipolesis in megakaryocytes between the 4th and 8th days of the experiment was caused by the toxic action of colchicine and may indicate the labilisation of cell membranes and microtubule depolymerisation.

Abnormalities in the replicative capacity of osteoblastic cells in the proximal femur of patients with osteonecrosis of the femoral head.

OBJECTIVE: Aseptic nontraumatic osteonecrosis (ON) of the femoral head is a painful disorder that often leads to femoral head collapse due to subchondral fracture. We postulated that alteration of osteoblast function might play a role in the pathophysiology of ON. We evaluated the ex vivo proliferation rate and differentiation capacity of osteoblasts derived from the intertrochanteric region of the femur and of the iliac crest of patients with ON of the femoral head and compared it with patients with hip osteoarthritis (OA). METHODS: We examined the function of osteoblastic cells in cultures derived from bone biopsies of the intertrochanteric region of the femur and of the iliac crest obtained from 13 patients with ON of the femoral head and 8 patients with hip OA. The replicative capacity was assessed by the proliferation rate in secondary culture. The phenotypic characterization was evaluated by the level of alkaline phosphatase activity, the sensitivity to 1,25 (OH)2 vitamin D3, and collagen synthesis. RESULTS: The replicative capacity of the osteoblastic cells of the intertrochanteric area of the femur in ON patients was significantly reduced compared to patients with OA. The capacity of differentiation, however, was not different between ON and OA patients. CONCLUSION: The replicative capacity of osteoblastic cells is significantly reduced in the femur of patients with ON. Our results confirm that altered osteoblastic function plays a role in the pathophysiology of ON of the femoral head.

Infecton is not specific for bacterial osteo-articular infective pathology.

The aim of this study was to re-examine, by retrospective analysis of our case material, the specificity and sensitivity of technetium-99m ciprofloxacin scan in discriminating between infection and other conditions. (99m)Tc-ciprofloxacin scintigraphy was performed in 71 patients: 30 patients referred for suspicion of osteomyelitis (OM) or septic arthritis (SA) (group 1) and 41 controls (group 2). Imaging was performed at 4 h post injection and, when possible, at 8 or 24 h post injection. Tracer uptake was visually assessed in different joint groups, and in the sites suspicious for infection. Several soft tissue sites were also evaluated. In the group referred for osteo-articular infection, we found a lower specificity (54.5%) than has previously been reported in the literature. Evaluation of tracer uptake at late imaging did not improve discrimination between sterile and non-sterile inflammation. Additionally, articular uptake was seen in many control patients. Infecton uptake in growth cartilage, thyroid gland, vascular pool, lungs, liver and intestines is discussed.