[Mid-term and long-term results of metal-on-metal total hip arthroplasty]

To assess mid-term and long-term results of metal-on-metal total hip arthroplasty.

There were 349 operations for the period 2006-2012 in our clinic. Sixty-four patients underwent a full examination. All patients underwent X-ray examination of the pelvis, MRI of hip joint with metal artifact reduction sequence (MARS). The concentration of cobalt and chromium metal ions was determined in blood serum. Each patient completed a questionnaire (Harris, Oxford, Womac, SF-36). 'Survival' of endoprostheses was calculated using the Kaplan-Meier method.

According to the Oxford scale, 76.6% of patients had excellent clinical and functional outcomes, 10.9% - good, 9.4% - satisfactory, 3.1% - unsatisfactory. According to the Harris scale, 57.9% of patients had excellent results, 15.6% - good, 7.8% - satisfactory, 18.7% - unsatisfactory. Inclination less than 45 degrees was noted in 77.2% of acetabular components. It is optimal installation angle. According to MRI data, effusion was the main type of periprosthetic changes (16 cases). There were no periprosthetic changes in 33 cases. Pseudotumor was diagnosed in 5 cases. Mean concentrations of cobalt and chromium ions were 1.27 (13.57-0.12) and 0.59 (0.4-0.87) µg/l, respectively. Normal concentration of chromium ions was observed in all cases. Kaplan-Meier survival rate of endoprostheses was 89% (80-97%).

There was no correlation between female sex, young age of patients and incidence of complications. It is necessary to exclude pseudotumor in case of pain syndrome and no signs of aseptic loosening of the components of the endoprosthesis.