Evaluation of the TiMo12Zr6Fe2 alloy for orthopaedic implants: in vitro biocompatibility study by using primary human fibroblasts and osteoblasts.

To reveal the biocompatibility of TiMo12Zr6Fe2 (TMZF), a new titanium alloy used since 1998 for orthopaedic prosthesis, we compared the behavior of primary human fibroblasts and osteoblasts grown on TMZF discs or on plastic tissue culture dishes, a widely used material specifically treated by the manufacturer to enhance cell growth. Proliferation, differentiation. RNA and collagen type I expression level of human cells were carried out. The analysis were performed over a period of 96 h. Fibroblasts behaved at the same way on the two different supports after 48 h, their number increased after 96 h when cells were grown on the alloy. Osteoblasts adhered and proliferated on the alloy discs as well as on plastic. RNA expression level was not affected. Interestingly, cell number at each time point was higher for fibroblasts than for osteoblasts. The RNA expression level was higher for the osteoblasts. Both cell types cultured on the alloy revealed an increase in the amount of type I collagen and a similar electrophoretic pattern was found for collagen produced by fibroblasts and osteoblasts grown on either supports. These results indicate good biocompatibility of the TMZF alloy, which allowed adhesion and proliferation of both the examined cell types and suggest that TMZF is a promising material for orthopaedic implants.

The role of mineralization in experimental models of osteogenetic induction with decalcified bone matrix.

The role of mineralization was studied in an experimental model of osteoinduction consisting of the implant of decalcified bone matrix in the rat muscle. After vascular connective tissue invasion of the matrix, the first phenomena is the appearance of hydroxyapatite crystals in the area of chondroid metaplasia from where the deposit of calcium-phosphate is extended to the surrounding decalcified matrix. The recalcified areas act as a substratum for the neo-osteogenesis. The appearances observed reproduced those of enchondral ossification, where the first osteoblasts differentiated on the calcified cartilaginous matrix and began to supply new bone matrix. Non-decalcified bone matrix implants were surrounded by a connective tissue capsule with features identical to those of a foreign body reaction and with total absence of vascular invasion. The absence of induction in this type of implant may be related either to masking of the osteoinducing protein in the calcified matrix, or to the absence of cells with osteogenic differentiation potential due to the lack of cellular invasion of the implant.

An epiphyseal giant cell tumor associated with early Paget's disease. A case report.

An epiphyseal giant cell tumor occurred in a 50-year-old woman in the absence of roentgenographic signs of Paget's disease adjacent to the tumor area. Only one case with similar features has been previously reported. Treatment increased bone remodeling changes in the whole femur. Two years later the high bone turnover of the femur was arrested. This case suggests that a giant cell tumor of the epiphysis developed in an early phase of Paget's disease.

Evaluation of reimplant total hip prostheses and resection arthroplasty.

Results of reimplanted total hip prostheses and resection arthroplasty were compared. Using the Iowa hip rating scale, the reimplanted prostheses population was rated higher for function, gait, and absence of deformity, however, the resection arthroplasty population rated better in freedom from pain. Radiographic findings in the reimplanted prostheses population included radiolucent lines around the cement, loosening, and cortex bone stock loss. These findings cause concern for the future of these implants. Repair and remodeling of the bone lesions were observed in resection arthroplasties. It was concluded that if healing of infection is achieved or if resection is performed for mechanical failure, the results may be considered permanent.

Chondrodystrophic dwarfism and multiple malformations in two sisters.

A genetic skeletal dysplasia with dwarfism, scoliosis and multiple skeletal defects was observed in two sisters. Only nine cases with similar features have been reported in the literature.

Failure of the stem in total hip replacement. A study of aetiology and mechanism of failure in 13 cases.

Thirteen failed stem of Total Hip Replacement were studied: 9 were Charnley THR from an homogeneous series, which gives an incidence of 2.4% of stem fractures with a follow-up of 9-16 years; 4 were Mueller THR. Fatigue fracture of the stem occurred by defective support of the proximal part of the femur, following resorption of the calcar. In all cases reactive tissue to foreign body particles, metal and polyethylene, was found where bone resorption occurred. In Mueller THR wear of the cup produced the large amount of polyethylene particles; in Charnley THR metal particles prevailed and corrosion of the stem is suggested to be the initiating factor.

Pathogenesis of membranous lipodystrophy. Case report and review of the literature.

Membranous lipodystrophy occurred in a 35-year-old woman and membrane-like material was found in her epiphyses and short bones. Electron microscopy allowed a study of the relationship between the pathologic tissue and normal fat, suggesting that the membrane-like material is derived from degenerated cells. Nucleation of hydroxyapatite crystals was also observed in the membranous material. Because basal ganglia calcifications were demonstrated with the use of computed tomography, brain and bone lesions may be assumed to share the same pathogenesis. Lipid and mucopolysaccharide metabolism was found to be normal.

Lymphangiomatosis of the arm with massive osteolysis. A case report.

A case of massive osteolysis of the arm is described where the typical bony lesions were associated with soft tissue lymphangiomatosis.

Metal ions in body fluids after arthroplasty.

We measured levels of metal ions in urine and plasma of 17 patients 7-15 years after they had a Co-Cr-Mo alloy total hip replacement. They had higher levels of cobalt and chromium than controls. No case of skin sensitivity to the investigated metals was observed. The values of cobalt and chromium in plasma and urine were considerably lower than in professionally exposed groups and do not represent a toxic hazard for the patients.

Periosteal chondroma of the humerus leading to shortening. A case report.

We report a case of periosteal chondroma of the proximal humerus with multiple cartilaginous masses extending around two-thirds of the metaphysial circumference. The humerus was short, presumably because the tumour interfered with growth at the epiphysial plate.

Involvement of metal particles in loosening of metal-plastic total hip prostheses.

Four loosened metal-on-plastic total hip prostheses and associated tissues were examined. Each implant showed an uncommonly high formation of metal particles produced by wear or corrosion of the femoral stem. The granulation tissue between bone and cement was characterized by macrophages containing metal particles. Histological, histochemical, and ultrastructural investigations have been performed to assess cellular reactions to ingested metal particles. Pathogenesis of loosening in these cases is discussed in relation to the role of macrophages in bone resorption.

[X-ray features of the long-term follow-up (l0-12 years) of the Charnley hip prosthesis fixed with acrylic cement]. / Quadri radiografici a distanza (10-12 anni) delle protesiarticolari d'anca di Charnley fissate con cemento acrilico.

A long term follow-up (10 divided by 12 years) of Charnley total hip arthroplasties fixed with radiopaque acrylic cement is reported. Clinical results and X-rays features have been correlated and discussed with reference to the bone reaction and to the diagnostic possibilities of standard radiographs. A radiographic diagnosis of loosening preceding relevant clinical symptom may allow revision arthroplasty before anatomical situation becomes too deteriorated.

Metal determination in organic fluids of patients with stainless steel hip arthroplasty.

In 20 stainless steel Charnley hip arthroplasties (with a follow-up of 10-13 years) nickel, chromium and manganese levels were measured in blood, plasma and urine by atomic absorption spectrophotometry. Skin patch tests for these metals, and clinical and roentgenographic results of arthroplasty were also assessed. Metal levels in organic fluids were plotted against a control population homogeneous for age, residence and anamnestic conditions with the first, but which had never undergone a prosthesis or other metallic implant surgical procedure. Nickel levels in blood, plasma and urine, manganese levels in blood and urine and chromium levels in plasma were significantly higher in the hip prostheses population. Metal ion release from stainless steel prostheses is discussed with regard to implant failure, metal sensitivity and carcinogenesis.

Reaction to methylmethacrylate in bone metastases treated by surgical curetting and filling with acrylic cement. Histological study of a case.

A femur bone metastasis from breast carcinoma was treated by curetting and filling with acrylic cement and osteosynthesis. The histological study of the resected proximal third of the femur five months after surgery shows a thin layer of connective tissue between bone and cement. There are no neoplastic cells in this connective tissue nor in the spongious bone of the proximal femur. Instead the diaphyseal channel is fully invaded with neoplastic cells. Pathogenesis and validity of surgical treatment by the emptying and filling with acrylic cement of bone metastases are discussed.

Fractures in haemophilia.

Eight cases of fractures in haemophiliac patients are presented. The clinical and radiological features, behaviour and response to treatment indicate that they are normal, not pathological fractures. If fractures in haemophiliac patients are treated early and correctly both from a haematological and orthopaedic point of view, the results are comparable with those in normal subjects. The haematological and orthopaedic management is discussed.