Variability of pre-operative functional pelvic tilt in total hip arthroplasty patients

PurposePelvic tilt (PT) is important to consider when planning total hip arthroplasty (THA) due to its dynamic impact on acetabular orientation. The degree of sagittal pelvic rotation varies during functional activities and can be difficult to measure without proper imaging. The purpose of this study was to evaluate PT variation in the supine, standing, and seated positions.MethodsA multi-centre cross-sectional study was performed that included 358 THA patients who had preo-perative PT measured from supine CT scan and standing and upright seated lateral radiographs. Supine, standing, and seated PT and associated changes between functional positions were evaluated. Anterior PT was assigned a positive value.ResultsIn the supine position, mean PT was 4 degrees (range, -35 degrees to 20 degrees), where 23% had posterior PT and 69% anterior PT. In the standing position, mean PT was 1 degrees (range, -23 degrees to 29 degrees), where 40% had posterior PT and 54% anterior PT. In the seated position, mean PT was -18 degrees (range, -43 degrees to 47 degrees), where 95% had posterior PT and 4% anterior PT. From standing to seated, the pelvis rotated posteriorly in 97% of cases (maximum 60 degrees) with 16% of cases considered stiff (change <= 10 degrees) and 18% of cases considered hypermobile (change >= 30 degrees).ConclusionPatients undergoing THA have marked PT variation in the supine, standing, and seated positions. There was wide variability in PT change from standing to seated, with 16% of patients considered stiff and 18% considered hypermobile. Functional imaging should be performed on patients prior to THA to allow for more accurate planning.

Automated summary

The purpose of this study was to evaluate the variation of pelvic tilt during total hip arthroplasty (THA), and the results showed that there were significant differences in pelvic tilt among patients in supine, standing, and seated positions. The pelvis rotated posteriorly from standing to seated. Therefore, functional imaging should be performed prior to THA for more accurate surgical planning.