[Effect of ultrasonic shock waves on the bone-bone cement interface]. / Pusobení ultrazvukové rázové vlny na spojení kostního cementu s kostí.

PURPOSE OF THE STUDY: Identification of the impact of ultrasound shock wave on the integration of bone cement in the bone and the examination of a potential application of this method in order to facilitate the extraction of cemented implants, mainly femoral component of total hip arthroplasty. MATERIAL: We used pig proximal femurs from which we made fragments involving approximately one third to one half of the profile of the bone and Palacos bone cement. METHOD: We made a groove in the cancellous bone, pressed bone cement with a wire loop in the cavity and let it harden. The samples were divided by random selection into two groups. Samples from A group were exposed to ultrasound shock waves and group B served as a control group. Then we measured the force needed for the extraction of the cement plug from the bone. RESULTS: Our measuring has shown an evident decrease of the force necessary for the extraction of the bone cement after the application of ultrasound shock wave. We did not find out any macroscopically evident damage of the bone cement or of the surrounding cortical bone. DISCUSSION: The results of our measuring are influenced by a different shape and size of the examined samples which also substantially differ from the situation when a stem of the endoprosthesis is implanted in the femoral canal and is surrounded by a cement mantle. As concerns risks associated with the application of the shock wave in this indication there is a risk of a fracture of the cortical bone around THR stem (the literature does not mention this complication) and a risk of the increase of pressure in the medullary cavity of the femur combined with a risk of fat embolism. In our view this increase of pressure is comparable with the effect of the implantation of femoral component. This method cannot be used for releasing cementless implants as the surrounding cortical bone gets damaged before the implant is released. CONCLUSION: Ultrasound shock wave is still used rarely in orthopaedics, however, the existing results are promising in many aspects. Of great importance is the fact that it is a non-invasive method. The field dealt with by this work covers only experiments in vitro but the results provide hope for a future clinical use.

[Effect of shock waves on hip prosthesis implantation (preliminary report)]. / Pusobení rázové vlny na implantovanou kycelní náhradu (predbezné sdelení).

Revision of total hip arthroplasty has increased dramatically and it began to be a big problem, because of the number of reoperation is growing directly with the number of primoimplantation. Extraction of bone cement from the canal of the femur is timely and technically very difficult and related with many complications. Therapy by ESWL was applicated in clinical praxis for the first time in the therapy of urolithiasis and then choledocholithiasis. Now it is used in orthopedy for the therapy of pseudoarthrosis, entesopathia and anthores. In our experiment we used models of pork femur to which we implanted the endoprothesis to bone cement. We expouned these samples to ESWL and controlled the ability of releasing of the endoprothesis. We replayed the experiment for four times after an abnormal number of shockwaves (more than 8,000 shocks), in two cases endoprothesis release spontaneously, in one case we needed a little power to release it and in the four cases the releasing was not achieved. These results show the probable influence of the shockwaves between the layers metal-cement and cement-bone spongiosa.

[Dietary intake in the urban and rural populations of the Cap-Bon]. / Apports alimentaires dans la population urbaine et rurale du Cap-Bon.

BACKGROUND: An assessment of nutriment intake (protein, carbohydrates, fat) was collected from a baseline survey of risk factors for cardiovascular diseases from the urban and rural population of the North East of Tunisia (Cap-Bon). METHODS: 692 men and women, 35-50-year-old, were examined. The sample was randomly selected on the basis of the 1984 census from the population of Cap-Bon. A standardized 24-hour recall and a semi-quantitative food frequency questionnaire were used. RESULTS: The amount of food consumed differed between men and women (expressed in absolute value), but no significant difference was shown between men and women when food intake was expressed in relative value (contribution to total energy intake). The living area (urban, rural) appears to be an important factor influencing nutritional intake. CONCLUSION: In the urban population, the increase of protein and fat intake (saturated fat and dietary cholesterol) and the decrease of carbohydrates and fiber intake schematize the trend of dietary habits in Tunisia.