A radiological study of fractures of acrylic cement in relation to the stem of a femoral head prosthesis.
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The incidence and prognostic significance of fractures of acrylic cement related to the stem of a femoral head prosthesis in total hip replacement are examined. These fractures are demonstrated when the cement has been rendered radio-opaque by the addition of barium sulphate. One and a half percent of the radiographs of 6,649 patients showed these fractures, which were sometimes associated with subsidence of the prosthesis. Fracture of the cement was usually evident at the six-month post-operative review, if it occurred at all. This radiological complication was devoid of symptoms in the majority of cases and tended to occur in patients with excellent functional recovery. In a minority of patients pain in the thigh during the first six months seemed likely to be explained by this fracture. Slight subsidence of the prosthesis in the cement bed appeared to result in a new and final position of stability. The prognosis was very good; only when separation of the fracture exceeded about 4 millimetres was the prognosis doubtful, in which case a chronic deep infection might be suspected. Possible mechanical and structural causes of fracture of the cement are discussed. (+info)
Physical and chemical aspects of calcium phosphates used in spinal surgery.
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In 1983, Brown and Chow discovered the first calcium phosphate cement (CPC). This discovery opened a new era in the use of calcium phosphates (CaP) as bone substitute. The first commercial CPC have now been introduced, and porous CaP with totally new properties should follow soon. In this article, the CaP traditionally used in spinal surgery are compared with these new CaP. Particular emphasis is placed on the use of CPC for bone augmentation. (+info)
Bone substitutes in vertebroplasty.
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Vertebroplasty--percutaneous cement augmentation of vertebral bodies--is an efficient procedure for the treatment of painful vertebral fractures in osteoporosis. At the present time, polymethylmethacrylate (PMMA) is the only available cement with reports of clinical application and experience. The material is easy to handle, the radiopacity can be adapted by adding contrast dye, and it is mechanically efficient. Composite cements (acrylic cements in conjunction with ceramics) are bioactive, highly radiopaque, and feature excellent mechanical properties. One such cement, Cortoss, is currently undergoing clinical trials for vertebroplasty and has so far been shown to be a potentially valuable alternative to PMMA. Several in vitro studies with injectable calcium phosphate (CaP) cements show their feasibility and mechanical effectiveness. Animal studies confirm their biocompatibility and osteoconductivity. However, handling problems and the limited radiopacity of these cements currently preclude their clinical use. (+info)
Age of fracture and clinical outcomes of percutaneous vertebroplasty.
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BACKGROUND AND PURPOSE: The patient populations that are most likely to benefit from percutaneous vertebroplasty (PVP) are uncertain. Our purpose was to evaluate the effect of the age of vertebral compression fracture (VCF) on clinical improvement after PVP. METHODS: We performed a retrospective review of charts of patients who had undergone PVP for painful osteoporotic VCFs at our institution. The preprocedural and postprocedural outcome measurements of pain, mobility, and analgesic use were compared for 80 treatment sessions in 75 patients (122 total vertebrae treated). We assessed the association between the duration of pain before PVP and postprocedural outcomes by using multivariable analysis. RESULTS: Age of fracture at time of PVP was not independently associated with postprocedural pain or activity. Increasing age of fracture was independently associated with slightly greater postprocedural analgesic requirement, at least for patients who required narcotics at baseline before PVP. Greater preprocedural analgesic requirement was independently associated with greater postprocedural analgesic requirement. Reduced preprocedural mobility was independently associated with reduced postprocedural mobility. CONCLUSION: PVP is a highly efficacious therapy for relief of pain and improvement in mobility, regardless of fracture age. PVP also is efficacious in reducing analgesic requirement, although this effect may be slightly blunted in patients who require narcotics before the procedure and in those who have older fractures. (+info)
Cementless cup fixation in total hip arthroplasty after 5-8 years.
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A series of 199 total hip arthroplasties was performed using a porous-coated, hemispherical press-fit acetabular cup. At a mean follow-up of 91.5 months 158 cups were available for clinical and radiological review. The mean age of the patients at the time of the index arthroplasty was 62.5 years. The mean Harris Hip score at final follow-up was 87.3. No shells were revised although eccentric polyethylene wear prompted liner replacement in two cases. Osteolysis was noted in six cases but predominantly in relation to the femoral stem. Focal pelvic osteolytic lesions were rare. All the cups were classified as stable on radiography. (+info)
The performance of three vacuum-mixing cement guns--a comparison of the fatigue properties of simplex P cement.
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We tested three commercially available cement-mixing systems (Howmedica, Summit and Stryker). After mixing the cement was allowed to cure in metal moulds under standard conditions. Sixty-nine cement blocks were produced. The fatigue behavior of the blocks was tested until failure. A wide scattering of results was observed in all the three systems. Uneven mixing of the polymer and monomer was observed in the Howmedica system. A significantly stronger cement (P=0.018) was produced with the Stryker system. (+info)
The cytotoxic effect of methotrexate loaded bone cement on osteosarcoma cell lines.
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We mixed various amounts of methotrexate with bone cement and measured the absorbance daily for 4 weeks. The cytotoxic effects on SaOS2 and MG63 osteosarcoma cells were examined by the MTT assay, and analysed according to the methotrexate concentration and the elapsed time. The amount of eluted methotrexate was greatest during the first day, and then decreased rapidly reaching a plateau in the third week. The number of viable tumour cells decreased significantly after 72 h, and they were hardly seen after 1 week. (+info)
The use of vancomycin-impregnated cement beads in the management of infection of prosthetic joints.
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Although the incidence of infection associated with hip and knee prostheses is low, with the increasing number of arthroplasties being carried out, the total number of such cases is increasing. The pattern of infecting organisms after total joint arthroplasty has changed and gentamicin-resistant organisms are becoming increasingly common. In conjunction with surgical debridement, vancomycin added to a bone-cement carrier can be very effective in the treatment of infection caused by such organisms. We report the results of its use in proven deep infection in 26 hip and seven knee arthroplasties. After a mean follow-up of 67 months, 32 patients remained clinically and radiologically free from infection. There was one recurrence and positive second-stage cultures of uncertain significance in three other patients. Vancomycin is potentially very useful in the management of deep infection after arthroplasty. (+info)