Pidgaiska O. Grounging of stem choice at cementless total hip arthroplasty

Object: the process of adaptive remodeling of bone tissue of the proximal femur at different types of femoral canal and stem design. The aim: to improve the method of stem choice at cementless total hip arthroplasty. Methods: clinical , roentgenological, roentgendensitometry (measuring of optical bone density due to program complex "X-ray", dual energy absorciometry, mathematical modeling, statistical. Short-term and median-term results of total hip arthroplasty with the usage of different types of stems were studied. It was established that stem loosening and stress-shieldieng syndrome mostly were observed at cylindrical shape of femoral canal. New scientific data were obtained about regularities of bone density changes around stem at different shapes of femoral canal. The general trend of bone mineral density of periprosthetic region after total hip arthroplasty was revealed. Decreasing of bone density in the proximal part of femur and its compacting in the diaphysal region. Due to mathematic modeling peculiarities of tensions distribution in the system "femur-stem endoprothesis" were established at the different variants of femoral canals and stem designs. Calculations showed that tension distributions in the proximal femur depend on the shape of femoral canal and stem design. In the champagne-fluted canal loadings are perceived more evenly. In the cylindrical canal loadings are perceived asymmetrically which concentrate on the medial side of the femoral canal or near the tip of the stem at the usage of short stem, stems of proximal and methaphyseal fixation. The usage of stems of distal fixation in the cylindrical canal can provide evenly distribution of tensions. On the base of obtained results the method of stem choice was developed. Indications for stem choice of the different types of fixation in patients with the champagne-fluted, cylindrical and normal shapes of canal were specified. Observance of the developed rules of selection of a femoral component in each case allowed us to decrease the frequency of aseptic loosening and stress-shielding appearance after total hip arthroplasty. Applying of additional methods of investigation and the improved method of stem selection allowed us to choose femoral stem which can fit to the shape of femoral canal. The main results of the research have been applied in clinical practice of Kharkov regional clinical traumatological hospital; regional clinical hospitals of the cities Poltava, Kirovograd; department of emergency care and reconstructive surgery of SI "Sytenko Institute of Spine and Joint Pathology National Academy of Medical Sciences of Ukraine". In education process of orthopaedics and traumatological department of Kharkov medical academy of postgraduated education Ministry of Health care of Ukraine. Traumatology and Orthopedics.