Nuances of preoperative planning of total hip arthroplasty in patients with hip dysplasia

Purpose of the study - to evaluate in different groups of patients variability of anatomical changes that may affect the difference in the length of the lower extremities and affect on the results of the preoperative planning. Material and methods. As study material we used long film X-ays of 142 patients. A main group comprised 69 patients with varying severity of hip dysplasia. Control group consisted of 73 patients without hip pathology. All patients were performed long film X-rays, and measurements of relative and absolute lengths of the lower limbs, followed by analysis of the data. Results. Analysis of the measurements showed that none of the patients had absolutely equal length of the lower limbs, even in the control group in 56.2% of the observations noted the absolute difference of the lower extremities length more than 5 mm, and in 9.6% of patients - from 20 to 35 mm. In assessing the difference of the lower extremities length on AP pelvic view in the main group only one patient of 69 had the same length of the legs, and in 61 cases the difference was more than 5 mm, that it was clinically significant. Of practical interest is the fact that in the main group shortening of the operated limb was observed in 51 of 69 patients in AP views of the pelvis, but the results of measurements of the anatomical length of limbs long film X-rays compared with measurements of the relative shortening on the pelvis AP views showed that clinically significant difference exceeding 5 mm between measurements observed in 68.1% of cases. The greatest difference between the measurements of the limbs length on the pelvis AP views and long film X-rays observed in patients with unilateral hip dislocation and averaged 17.0 mm. Conclusion. Performing preoperative planning in patients with dysplasia only on pelvis AP views not allow properly compensate the difference of the lower extremities lengths, which may adversely affect the functional results of surgery and as a result, the patient’s satisfaction. Therefore, planning THA, especially at high hip dislocation, it is necessary to calculate the difference of the lower extremities lengths considering as the difference of the lengths on AP pelvis views and long film X-rays.

hip dysplasia, total hip arthroplasty, long film X-rays, preoperative planning