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Published on: September 29, 2023
Quantitative three-dimensional fracture mapping reveals subtype-specific morphology of acetabular roof column and
Zihan Liu1,2, Zihang Zhao1,2, Xi Hou1,2
1Department of Orthopaedic Surgery, Third Hospital of Hebei Medical University, Shijiazhuang, China.
Introduction:
Acetabular roof column and wall fractures (A3 injuries) are uncommon injuries involving the acetabular roof, but their subtype-specific three-dimensional morphology remains incompletely quantified.
Methods:
This multicenter retrospective study characterized the fracture-line distribution and geometric features of A3.1-A3.3 injuries using standardized CT-based three-dimensional reconstruction and fracture mapping. Among 3,248 patients with acetabular fractures screened at nine level-I trauma centers between January 2017 and December 2022, 89 had A3 injuries, and 46 surgically treated patients with adequate CT data were included. CT data were reconstructed in Mimics and processed in 3-Matic for fragment separation, virtual reduction, fracture-line tracing, surface-area measurement, displacement assessment, and angular analysis. Fracture trajectories were registered to a standardized left-sided hemipelvic template to generate subtype-specific fracture maps and an overall heat map.
Results:
A3.1 fractures showed shorter three-dimensional perifragment fracture-boundary length but greater fragment displacement and angular change, whereas A3.2 and A3.3 fractures demonstrated longer cranial trajectories and larger extra-fossa surface involvement. No statistically significant difference in intra-fossa surface area was detected among subtypes. Classification agreement was substantial, and quantitative measurements showed excellent reliability.
Discussion:
Quantitative three-dimensional mapping identified distinct morphologic patterns among A3 roof injuries. Rotational displacement of a localized roof fragment was a key morphology-based concern in A3.1 injuries, whereas A3.2 and A3.3 injuries showed broader cranial extension and greater extra-fossa involvement that may warrant further investigation in relation to fixation coverage and clinical outcomes. Because the cohort included only surgically treated patients with adequate CT data, these findings should be interpreted primarily in the context of more displaced or complex A3 injuries and may not be generalizable to minimally displaced or nonoperatively managed injuries.
