Closed reduction and casting of thoracolumbar and lumbar burst fractures is a safe treatment method that yields acceptable functional and radiographic results.

In term of kinematics during the chronology of whiplash, two injury phases were identified: the first was hyperextension of the lower cervical spine (C6-C7 and C5-C6) and mild flexion of the upper cervical spine(C0-C4). The amount of upper cervical flexion was 15 degrees from C0 to C4. The second phase was hyperextension of the entire cervical spine. Potential patterns of ligamentous injuries were observed; the anterior longitudinal ligament experienced the most strain (30%) at the lower cervical spine at the time of lower cervical extension and the interspinous ligament experienced the most strain (60%) at the time of upper cervical flexion. Von Mises stresses in bone do not exceed 15 Mpa, which is largely under injury levels reported in the literature. CONCLUSIONS.: This study reports a methodology to describe and postulate on human injuries based on finite element model analysis. The output of the HUMOS model in the context of whiplash shows a strong correlation with clinical and experimental reported data. HUMOS shows promise for the modeling of other types of trauma as well.

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This study investigated cytotoxicity of cement fragments harvested from two prosthesis revisions by the MTT test using L929 fibroblasts and human osteoblasts. The results did not show any toxicity of the extracts prepared after 48 and 78 months implantation. We consider that no MMA monomer has been released from the cement fragments. Histological studies on undecalcified samples harvested around revising prosthesis from 11 patients were used to evaluate tissue reactions at the bone-cement interface after 2-168 months implantation. Cement and prosthesis particles (5-35 microm) either dispersed or forming a layer were observed. A fibrous tissue layer, osteolysis, and osteonecrosis areas were observed at the interface. Besides, fibroblasts, macrophages, and multinucleated giant cells were also observed. New bone formation with osteoid, osteoblasts, and endochondral ossification with fibrocartilaginous tissue has been observed. The tissue reactions seemed to decrease with time. However, osseous trabeculae fractures were observed in the samples after 19 months. Although we consider that monomer toxicity, exothermic reaction, and particles formation may cause short-term prosthesis loosening; the trabeculae fractures may be due to prosthesis and bone cement micromovements. This fractures and particles formation may cause long-term prosthesis loosening.

Fresh allografts of bone are commonly used for repairing small defects, but preserved grafts are required for replacing large sections of long bones. We have collected these grafts in sterile conditions and then preserved the specimens in liquid nitrogen at minus 196 degrees Celsius. Biological, histological and biomechanical studies have confirmed the value of this technique. The method preserves the normal architecture of bone and viable cartilage cells. The medullary cells are gradually destroyed in situ leaving a protein matrix to which mineral components are fixed. Neither of these are antigenic in allografts and immunological problems are rarely encountered. When the recipient site is well vascularised the graft becomes fully integrated within two or three years. Doubt has been expressed as to the functional viability of the cartilage in large allograft joint replacements, and is has been suggested that metal prostheses might be better. Research is in progress in the use of ligament allografts and on the use of bank bone with large prostheses. The functional results are satisfactory in more than 90% of patients treated with these large allografts.