Abstract
Purpose
The aim of this study is to describe the influence of sitting and standing posture on sagittal pelvic inclination in preoperative total hip replacement patients to assist with correct acetabular component positioning.
Methods
Lateral radiographs of the pelvis and lumbar spine in sitting and standing of preoperative hip arthroplasty patients with primary hip osteoarthritis were extracted. Pelvic tilt was measured using the vertical inclination of a line from the ASIS to pubic tubercle. Sacral inclination was measured as the angle between the anterior surface of the sacrum and a horizontal reference. Figure one is a representation of the pelvic tilt angle and sacrel inclination angle taken during standing. The Cobb angle of the lumbar spine was recorded represented for a sitting patient in figure 2. Hip flexion was recorded (figure 2).
Results
60 patients were identified. Mean age of the cohort was 63. Sacral inclination ranged from 1 to 55 degrees in standing with a mean of 25.7 degrees. In sitting, sacral inclination ranged from 0.3–84.5 degrees with a mean of 24.1 degrees. Pelvic tilt ranged from 30 degrees posteriorly to 21.5 degrees anteriorly in standing. Pelvic tilt in sitting and ranged from 48 posterior to 42 degrees anterior tiltLumbar lordosis ranged from 11.6 to 91.7 degrees in standing. Lumbar lordosis in sitting ranged from 29.5 degrees(kyphosis) to 42 degrees (lordosis). Total hip flexion was 107.4 degrees from standing to sitting.
Conclusions
There is wide variability in pelvic orientation between individuals in both postures Orientating acetabular components for total hip arthroplasty should account for postural changes in native version.
