Conditions for generation of polarized RF fields in cylindrical symmetry by high order coils are presented. Whole body NMR transmitters utilizing this principle would require a current control on a certain number of loops. In the present design this is obtained by feeding each loop by an appropriate linear combination of two in quadrature waves. The development has been experimentally tested by three scaled down experimental prototypes operated at 500 kHz and a good agreement has been found.

Humans↗

PubMedDate not supplied

Loss of bone mass after total hip replacement: preliminary data.

In a total of 37 females with cemented total hip replacement for monolateral coxarthrosis, of which 13 with prosthetic stem loosening, and 11 with monolateral coxarthrosis that is not prosthetized, bone mineral density (BMD) is determined by dual ray photonic absorbimetry selecting regions of interest (ROI) on the cortex of the femurs 4 cm under the lesser trochanter and on the ischium bilaterally. In females that are not prosthetized there are differences in bone mass between the two femurs and the ischium on both sides. In prosthetized patients BMD of the femur and of the ischium on the side operated on is significantly less than on the contralateral one (Student's "t" test: p < 0.001). In patients with stable prostheses, BMD of the femur operated on is greater than that in females with prosthetic stem loosening (Student's "t" test: p < 0.000). Based on a comparison between these two groups we did not observe any other significant differences in BMD among the ROI analyzed. BMD was correlated with the amount of time since surgery only in the ROIs in prosthetized femurs. The study confirms the significant bone resorption of the cortex in prosthetized femurs and documents analogously significant reduction in BMD in the ischium on the side operated on. Finally, it indicates that prosthetic stem loosening may be associated with loss of BMD in the femoral cortex which is significantly greater than that observed, during analogous periods of time in stable implants.

Aged↗

PubMedDate not supplied

Ilizarov external fixation in the treatment of comminuted leg fractures.

Fifty consecutive comminuted leg fractures were treated by Ilizarov external fixation. Eleven were closed fractures, 37 were Grade II, and 2 were Grade III open fractures. Forty-five fractures healed within 6 months. In 5 fractures the Ilizarov device was removed and healing occurred by intramedullary nailing (2 cases) and decortication (3 cases). The causes of failure were: rapid peroneal union or bone fragment necrosis. Subjective tolerance and fracture stability are limited by septic loosening of the wires requiring frame removal after 6 to 8 months. Excellent results may be obtained (no leg length discrepancy, no angulation, no rotation, no joint stiffness), but the time required for union is long and additional surgery is required.

Adolescent↗

PubMedDate not supplied

Preliminary results in 167 bioceramic cemented arthroplasties with five-year follow-up in patients aged 60 years or over.

A total of 167 ceramic-ceramic cemented arthroplasties with a mean follow-up of 62.5 months were evaluated. There were no signs of loosening in the femoral components. Loosening of the acetabulum was observed in 5 patients. A statistical study conducted on the two groups (the first aged under 70 years, the second aged 70 or over) did not reveal any relationship between failure of the acetabular component and the age of the patient. An evaluation of bone density based on the DXA system in 5 cases of loosening revealed its diminution in relation to follow-up parameters. Based on our experience, implantation of the ceramic-ceramic cemented prosthesis is a reliable choice in patients with good bone trophism, in those where there is a significant reduction in bone density; it is best to use polyethylene-ceramic implants.

Age Factors↗