The influence of spinopelvic relationships on late dislocation of the prosthetic femoral head after total hip arthroplasty

Objective. To analyze the influence of sagittal balance parameters on the risk of dislocations of the head of the femoral component of the hip joint endoprosthesis. Material and Methods . A retrospective analysis of medical records of 113 patients with idiopathic coxarthrosis who underwent unilateral total hip arthroplasty was performed. The study assessed the parameters characterizing the sagittal balance in patients without prosthetic femoral head dislocation in the postoperative period (Group 1; n = 60) and in patients treated for prosthetic femoral head dislocation (Group 2; n = 53). Comparison of indicators was carried out by non-parametric Mann – Whitney U-test, and identification of dislocation predictors – by building single- and multi-factor logistic regression models. Differences were considered statistically significant at the achieved significance level p < 0.05. Results. In Group 1, the type 3 sagittal balance according to Roussouly prevailed (48 %), in Group 2 – types 1, 2 and 4 (75 %). In patients with types 1 and 2 sagittal balance, the dislocations of the prosthetic femoral head occured 1.84 times more often than in patients with type 3, and that in patients with type 4 – 1.66 times more often. Conclusion. Patients with Roussouly type 3 sagittal balance have significantly lower risks of postoperative dislocation of the prosthetic femoral head, as compared with those with types 1, 2 and 4.