Bellas NJ, Baltrusaitis D, Torre BB, Baldino JB, Sedghi TI, Marrero DE, Solovyova O. Determination of a Safe Zone for Ischial Screw Placement in Total Hip Arthroplasty.
J Arthroplasty 2024;
39:157-161. [PMID:
37479194 DOI:
10.1016/j.arth.2023.07.010]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 07/09/2023] [Accepted: 07/13/2023] [Indexed: 07/23/2023] Open
Abstract
BACKGROUND
Implantation of acetabular components with supplemental screw fixation is commonly performed to improve osteointegration and long-term stability in total hip arthroplasty (THA). Placement of ischial screws improves stability in biomechanical studies, but can be technically challenging. The study aimed to provide a safe zone for ischial screw placement with reference to easily identifiable intra-operative landmarks.
METHODS
A retrospective review of patients was performed and 27 preoperative pelvis computed tomography scans were collected. After converting these images to 3-dimensional reconstructions of the pelvis, a safe zone for ischial screw placement was established with reference to the anterior superior iliac spine (ASIS) and the acetabular center and rim.
RESULTS
The safe zone of an ischial screw in the en face sagittal plane was a median of 17 degrees (interquartile range [IQR]: 11,23) anterior to 13 degrees (IQR: 10,18) posterior to the reference line from the ASIS through the center of the acetabulum. The safe zone in the coronal plane was 34 degrees (IQR: 18,68) medial to 13 degrees (IQR: 8,19) lateral from a start point 1 centimeter medial to the inferior acetabular rim with a screw length of 25 millimeters. An ischial screw optimized for length directed down the center of the ischium was qualitatively demonstrated to have a start point unobtainable intraoperatively, originating within the cotyloid fossa.
CONCLUSION
The ASIS, center of the acetabulum, and acetabular rim provide identifiable intraoperative landmarks for guiding ischial screw placement in hip arthroplasty.
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