The pelvis rotates in the sagittal plane during daily activities.
These rotations have a direct effect on the functional orientation
of the acetabulum. The aim of this study was to quantify changes
in pelvic tilt between different functional positions. Pre-operatively, pelvic tilt was measured in 1517 patients undergoing
total hip arthroplasty (THA) in three functional positions – supine,
standing and flexed seated (the moment when patients initiate rising
from a seated position). Supine pelvic tilt was measured from CT
scans, standing and flexed seated pelvic tilts were measured from standardised
lateral radiographs. Anterior pelvic tilt was assigned a positive
value.Aims
Patients and Methods
We report the results of a 4- to 17-year clinical and radiological follow-up of 264 Charnley first-generation stems in comparison with those of 402 second- and subsequent-generation stems. The incidence of fracture was 4.1% in first-generation stems and 0.5% in second- and subsequent-generation stems. The incidence of stem loosening requiring or likely to require revision was 3.1% in first-generation and 11.4% in second-generation stems. We believe that the increased loosening rate in second- and subsequent-generation stems is due to their larger cross-sectional area, which produces an increase in flexural stiffness.
