Pelvic positioning in the supine position leads to more consistent orientation of the acetabular component after total hip arthroplasty

Abstract

Aims This study aims to: determine the difference in pelvic position that occurs between surgery and radiographic, supine, postoperative assessment; examine how the difference in pelvic position influences subsequent component orientation; and establish whether differences in pelvic position, and thereafter component orientation, exist between total hip arthroplasties (THAs) performed in the supine versus the lateral decubitus positions. Patients and Methods The intra- and postoperative anteroposterior pelvic radiographs of 321 THAs were included; 167 were performed with the patient supine using the anterior approach and 154 were performed with the patient in the lateral decubitus using the posterior approach. The inclination and anteversion of the acetabular component was measured and the difference (Δ) between the intra- and postoperative radiographs was determined. The target zone was inclination/anteversion of 40°/20° (± 10°). Changes in the tilt, rotation, and obliquity of the pelvis on the intra- and postoperative radiographs were calculated from Δinclination/anteversion using the Levenberg–Marquardt algorithm. Results The mean postoperative inclination/anteversion was 40° (± 8°)/23° (± 9°) with Δinclination and/or Δanteversion > ± 10° in 74 (21%). Intraoperatively, the pelvis was anteriorly tilted by a mean of 4° (± 10°), internally rotated by a mean of 1° (± 10°) and adducted by a mean of 1° (± 5°). Having Δinclination and/or Δanteversion > ± 10° was associated with a 3.5 odds ratio of having the acetabular component outside the target zone. A greater proportion of THAs that were undertaken with the patient in the lateral decubitus position had Δinclination and/or Δanteversion > ± 10° (35.3%, 54/153) compared with those in the supine position (4.8%, 8/167; p < 0.001). A greater number of acetabular components were within the target zone in THAs undertaken with the patient in the supine position (72%, 120/167), compared with those in the lateral decubitus position (44%, 67/153; p < 0.001). Intraoperatively, the pelvis was more anteriorly tilted (p < 0.001) and more internally rotated (p = 0.04) when the patient was in the lateral decubitus position. Conclusion The pelvic position is more reliable when the patient is in the supine position, leading to more consistent orientation of the acetabular component. Significant differences in pelvic tilt and rotation are seen with the patient in the lateral decubitus position. Cite this article: Bone Joint J 2018;100-B:1280–8.

An accelerometer-based navigation system provides acetabular cup orientation accuracy comparable to that of computed tomography-based navigation during total hip arthroplasty in the supine position

“…This method was used because during surgery, tilt, rotation, and other pelvic parameters should be the same as they are during radiographic assessment. However, the mean intraoperative anterior pelvic tilt was 1.4°, with a mean internal rotation of 1.4°and a mean adduction of 0.9°with the patient in the supine position [11]. A difference in pelvic tilt makes it impossible to perform accurate comparisons of cup alignment on preoperative and postoperative CT images.…”

“…When THA is performed in the lateral decubitus position, the pelvic tilt error is large [10], and inadequate orientation of the acetabular component is a concern; however, when performed in the supine position, this error is smaller [11]. Nevertheless, the use of intraoperative fluoroscopy or X-ray to confirm alignment of the acetabular component is common.…”

Pelvic Tilt Reduces the Accuracy of Acetabular Component Placement When Using a Portable Navigation System: An In Vitro Study

“…The pelvic position is more reliable when the patient is in the supine position, leading to more consistent orientation of the acetabular component. Significant differences in pelvic tilt and rotation are seen with the patient in the lateral decubitus position [17]. The PNS could provide the good accuracy of cup orientation during THA in the supine position [7].…”

An accelerometer-based navigation system provides acetabular cup orientation accuracy comparable to that of computed tomography-based navigation during total hip arthroplasty in the supine position

“…This method was used because during surgery, tilt, rotation, and other pelvic parameters should be the same as they are during radiographic assessment. However, the mean intraoperative anterior pelvic tilt was 1.4°, with a mean internal rotation of 1.4° and a mean adduction of 0.9° with the patient in the supine position [27]. A difference in pelvic tilt makes it impossible to perform accurate comparisons of cup alignment on preoperative and postoperative CT images.…”