Journal of Musculoskeletal Trauma

Original Article

Sex-specific bottlenecks and risk zones in the retrograde superior pubic ramus screw corridor: a 3D CT-based morphometric cadaver study: Ji Won Jeong, Jung Tae Ahn, Gu Hee Jung, Kun Tae Kim; Received January 22, 2026 Accepted February 7, 2026 Published online March 26, 2026; DOI: https://doi.org/10.12671/jmt.2026.00066 [Epub ahead of print]

Abstract PDF Supplementary Material: Background
Superior ramus screw fixation is commonly used to stabilize anterior pelvic ring injuries but is constrained by a narrow, irregular, and curved intraosseous corridor. Trajectory-based morphometric analysis may assist in screw diameter selection and enable identification of reproducible anatomic constriction zones.
Methods
We conducted a cross-sectional computed tomography (CT)-based morphometric study of 82 cadaveric pelvises (42 males, 40 females). Bottleneck diameter was defined as the diameter of the largest fully contained virtual cylinder along the planned trajectory, and cylinder length was recorded. Orthogonal cross-sections at 9.5-mm intervals (up to 12 segments) were generated to measure segment-wise effective diameter (defined as twice the minimum centerline-to-cortex distance) and cortical clearance, which was used as a diameter-based safety margin. Segments were realigned to the acetabular start segment to define relative segment positions (Δ seg). Feasibility was assessed for prespecified screw diameters ranging from 3.5 to 7.3 mm.
Results
Mean bottleneck diameter was larger in males than in females (7.34±1.10 vs. 5.93±0.98 mm), whereas trajectory length was similar between sexes (127.85±8.54 vs. 128.85±8.20 mm). Δ seg realignment localized corridor constriction to two discrete zones: a preacetabular zone (Δ seg −6 to −4) and a periacetabular zone (Δ seg 1 to 2), where effective diameter and cortical clearance were most limited. Feasibility rates were 100% at 3.5–4.5 mm, 95.2% vs. 82.5% at 5.0 mm, 81.0% vs. 27.5% at 6.5 mm, and 59.5% vs. 10.0% at 7.3 mm in males and females, respectively.
Conclusions
Female models demonstrated smaller trajectory-wide bottleneck diameters and segment-wise effective diameters than male models. Acetabular-referenced Δ seg realignment identified two reproducible anatomic risk zones: a preacetabular zone adjacent to the obturator neurovascular bundle and a periacetabular zone near the external iliac vessels. At diameters ≥6.5 mm, cortical proximity increased more prominently in females than in males. Level of evidence: III.

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