[Periprosthetic bone remodeling after cementless hip endoprosthesis stem implantation]

The research was aimed at determining the course of the adaptation remodelling of the bone tissue basing on the changes in periprosthetic bone density of the THA with the employment of the computer densitometric x-ray analysis. The applied research methods made it possible to describe the characteristics of the adaptation remodelling of the femoral bone tissue around the implanted stem of the endoprosthesis and allowed to distinguish the stages included in the course of this process: I--the early stage, up to 6 months after an operation, characterised by decreasing of the roentgenological bone tissue density and the appearance of rarefaction and condensation lines of the bone along the stem, II--the late stage, starting 6 months after an operation, with its increasing roentgenological bone tissue density, holding back of stem settling, and the progression of bone growth and osteointegration led to the establishment of the connection between the stem and the surrounding bone tissue. The normal course of the adaptation remodelling of the periprosthesis bone tissue is characterised by the decrease in the density of bone tissue surrounding the stem, which does not exceed 2% of it preoperative value, absence of settling of the stem or its nonprogressive settling, and gradual increase in the periprosthesis bone tissue taking part not earlier than 6 moths after an operation, which creates conditions for osteointegration and establishment of further durable connection between the stem and the bone through bone ingrow. An irregular course of the adaptation remodelling of the periprosthesis bone tissue is characterised by the decrease in bone density after an operation, which does not exceed 5% of its preoperational state, followed by the absence of increase in bone density, continuous settling of the stem, which does not exceed 3 mm a year, and atrophy of strain within the area of the small trochanter and its concentration at the stem level. These symptoms are indicative of the disturbance of osteointegration and bone growth processes and of a high risk of the aseptic loosening of an endoprosthesis.