Computer-navigated total hip arthroplasty (THA) is an increasingly common surgical procedure. One of the current iterations of computer navigation requires temporary intra-osseous pins to be drilled into theiliac crestin order to attach reference arrays to the iliac crest to allow for digital mapping and planning. Currently there is no formal approach for selecting the point along the iliac crest, or the angles and depth when drilling these pins. This study aimed to use 3D reconstructions of CT pelvis studies in order to formally define the...

A retrospective series of CT pelvis studies were selected at random from existing studies performed at Austin Health. The following selection criteria were employed: 1.Studies were performed within the last 36 months; 2.Patients were aged between 65 and 75 at the time of the study; 3.Patients could not have bony malignancy of the pelvis, or the femur; 4. Patients could not have metalware in-situ. Serial studies were assessed for eligibility by an unblinded assessor until 10 female and 10 male studies that met criteria were...

All 20 (100%) patients were able to be assessed and included in statistical analysis. Each of the measurements were analysed by gender to calculate mean and standard deviation. A Levene’s test was performed and revealed that the variances between the male and female cohorts were not statistically significant. The coronal plane angle, how medially the pin is to be angled, was the only statistically different parameter between groups (female 30.13 vs male 24.91,P = 0.034). The difference between the remaining parameters (female vs male) were...

This study is the first to retrospectively use patient-specific data and 3D reconstructions to propose a novel method for surgeons to intraoperatively locate the optimal site and angles to maximise pin containment within the iliac wing. By formally assessing the bony density in terms of coronal and sagittal planes of both males and females the study has demonstrated that surgeons need to be aware that the pin must be angled more medially when drilling into the female pelvis. This study has therefore provided a formal...

Malachy Feeney1, Michael Galea2, Kevin Phan3, Andrew Hardidge4 1. Department of Surgery, Austin Health, Melbourne, Australia. 2. Department of Radiology, Austin Health, Melbourne, Australia. 3. Department of Surgery, Prince of Wales Clinical School, University of New South Wales (UNSW), Sydney, Australia. 4. Department of Orthopaedic Surgery, Austin Health, Melbourne, Australia.

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