Sex-specific Differences of the Infraacetabular Corridor: A Biomorphometric CT-based Analysis on a Database of 523 Pelves

Abstract

Background An infraacetabular screw path facilitates the closure of a periacetabular fixation frame to increase the plate fixation strength in acetabular fractures up to 50%. Knowledge of the variance in corridor sizes and axes has substantial surgical relevance for safe screw placement. Questions/purposes (1) What proportion of healthy pelvis specimens have an infraacetabular corridor that is 5 mm or larger in diameter? (2) Does a universal corridor axis and specific screw entry point exist? (3) Are there sex-specific differences in the infraacetabular corridor size or axis and are these correlated with anthropometric parameters like age, body weight and height, or the acetabular diameter? Methods A template pelvis with a mean shape from 523 segmented pelvis specimens was generated using a CTbased advanced image analyzing system. Each individual pelvis was registered to the template using a free-form registration algorithm. Feasible surface regions for the entry and exit points of the infraacetabular corridor were marked on the template and automatically mapped to the individual samples to perform a measurement of the maximum sizes and axes of the infraacetabular corridor on each specimen. A minimum corridor diameter of at least 5 mm was defined as a cutoff for placing a 3.5-mm cortical screw in clinical settings. Results In 484 of 523 pelves (93%), an infraacetabular corridor with a diameter of at least 5 mm was found. Using the mean axis angulations (54.8°[95% confidence interval {CI}, 0.6] from anterocranial to posterocaudal in relation to the anterior pelvic plane and 1.5°[95% CI, 0.4] from anteromedial to posterolateral in relation to the sagittal midline plane), a sufficient osseous corridor was present in 64% of pelves. Allowing adjustment of the three-dimensional axis by another 5°included an additional 25% of pelves. All corridor parameters were different between females and males (corridor diameter, 6.9 [95% CI, 0

Transsacral Osseous Corridor Anatomy Is More Amenable To Screw Insertion In Males: A Biomorphometric Analysis of 280 Pelves

“…The specimens were processed as described [10,32]. A mean shape (the template) was generated from all input data sets (Fig.…”

Recommendations for iliosacral screw placement in dysmorphic sacrum based on modified in‐out‐in corridors

“…Second, only bone surfaces were segmented. This does not facilitate the automatic measurement of the inner diameter of the osseous corridors (the cortical thickness was not exactly considered) …”

“…This does not facilitate the automatic measurement of the inner diameter of the osseous corridors (the cortical thickness was not exactly considered). 10,27 Third, whereas the software performed most measurement algorithms, the only investigator-dependent step was the manual modification of the diameter for the in-out-in corridor, for which no intra-or interobserver reliability was evaluated.…”

“…The specimens were processed as recently described in detail . Briefly, a radiological‐trained physician (Dr. G. Kliegis, nordcom medical systems GmbH, Heikendorf, Germany) performed all segmentations, manually.…”

“…The specimens were processed as recently described in detail. 10,27,28 Briefly, a radiological-trained physician (Dr. G. Kliegis, nordcom medical systems GmbH, Heikendorf, Germany) performed all segmentations, manually. In the next step, two surface regions were determined on a template pelvis manually: (i) the entry region where the screw should enter the bone (on the lateral iliac cortex) and (ii) the exit region through which the screw should exit the bone (on the surface of the first sacral vertebra on the level of S1, respectively the contralateral lateral ilium cortex on the level of S2).…”