TESTING THE COBALT ION EMISSION ON THE STAND FOR DIFFERENT ANGLES OF POSITIONING THE COMPONENTS OF THE METAL–METAL HIP JOINT ENDOPROSTHESIS

The paper deals with the subject related to the assessment of the influence of the axis angle of the metal components of the hip joint on the emission of cobalt ions. The tribological tests were carried out with the use of a simulator for the examination of hip joint endoprostheses, the structure of which enables the fixation of endoprosthesis components in accordance with the anatomical structure of the human hip joint. During the tests, the simulator performs flexion and extension movements as well as loads occurring in the human hip joint while walking. Loss-wear tests were carried out for nine variants of the “head–cup” system settings. These settings were determined on the basis of CT images obtained from patients after arthroplasty. After the tribological tests were completed, samples of the lubricating fluid with the wear products suspended in it were collected in order to determine the concentration of cobalt ions, which was carried out using the atomic absorption spectrometry method. As a result, the influence of the head antetorsion angle (α) and the acetabular anteversion angle (β) on the concentration of cobalt ions was analysed.

CLINICAL AND ROENTGENOLOGICAL CRITERIA OF SPINE-PELVIS RATIOS IN CHILDREN WITH DYSPLASTIC FEMUR SUBLUXATION

Aim of the study— to identify clinical and roentgenological criteria of the sagittal profile status of spine-pelvissegment in children with dysplastic femur subluxation.Material and Methods.The present study included 40 female patients (50 hip joints) aged from 12 to 17 years(14.7±1.58) with unilateral and bilateral hip joint instability due to dysplasia. Children were divided into two groups – the first group included 30 patients (30 hip joints) with unilateral femur subluxation, the second group – 10 patients (20 hip joints) with bilateral femur subluxation. All patients underwent a standard orthopaedic clinical examination using a specialized scale to objectify complaints. All patients underwent X-ray examination of hip joints in AP and Lauenstein projections, CT scanning as well as lateral panoramic roentgenography of C1-S1 including femoral bones in standing position of the patient.Results.The authors observed a strong positive correlation between sacrum inclination and lumbar lordosiscurvature, antetorsion angle of proximal femur and sacrum inclination angle, severity of pain syndrome during impingement test and sacrum tilt: Pearson correlation coefficient was 0.71, 0.81 and 0.88 respectively. The authors reported in all patients a thoracic normokyphosis and lumbar hyperlordosis with excessive pelvis anteversion. Global sagittal disbalance was observed in all patients.Conclusion.Apart from typical anatomical and roentgenological changes in pelvic and femoral componentsofthe joint the children with dysplastic femur subluxation are characterized by excessive pelvic anteversion. Criteria of above parameters are identical and do not depend on the number of joints involved into the pathological process. Cranial dislocation of femoral head results to abnormalities of sagittal spine-pelvis ratios. Pathological process in hip joints and abnormality of spine-pelvis ratios results in negative changes of sagittal spine profile in the form of hyperlordosis, of physiological criteria of thoracic kyphosis and of the global sagittal disbalance. All of the above leads to overload of spinal motion segments and development of spine degenerative and dystrophic changes at early age.