Related Experiment Video
Updated: Jan 27, 2026
Individualized Stem-positioning in Calcar-guided Short-stem Total Hip Arthroplasty
Published on: February 27, 2018
Correlation of radiographic variables to guide safe implant positioning during acetabular surgery and hip
Simon Tiziani1, Georg Osterhoff1, Jan-Farei Campagna2
11Department for Trauma, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland.
Background:
Knowledge of periacetabular anatomy is crucial for prosthetic cup placement in total hip arthroplasty and for screw placement in anterior fixation with acetabular fractures. It is known that degree of hip dysplasia correlates with medial bone stock and that medial bone stock shows a weak correlation to Lequesne's acetabular index (AI). Aim of this study was to investigate a possible correlation between AI and the newly proposed medial safe zone.
Methods:
AI and the medial save zone were measured on 419 hips using a computed-tomography scan of the pelvis. AI was assessed on a 2D reconstructed anterior-posterior view of the pelvis using VOXAR™. Correlation was measured using the Pearson correlation coefficient.
Results:
Mean AI was 4.2 degrees (SD 4.9 degrees). Mean medial safe zone was 8.1 mm (SD 1.9 mm). There was a significant correlation between AI and medial save space with a Pearson correlation coefficient r = 0.33 (p = .001).
Conclusion:
There is a weak correlation between AI and medial safe zone. AI should not be used to predict medial safe zone. Due to the weakness in correlation AI is not suited for predicting medial safe zone. However, a low or negative AI can be a warning sign for less medial safe zone, prompting surgeons to take care when reaming in THA or placing periacetabular screws.
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