Defining the iliac wing osseous fixation pathways: anatomy and implant constriction points

Area of Science:

• Orthopedic surgery
• Anatomy
• Biomechanical engineering

Background:

• Iliac wing implant placement requires understanding the ilium's complex shape.
• Quantitative data on the iliac inner-outer table convergence (IOTC) and gluteal pillar is limited.

Purpose of the Study:

• To quantitatively identify the IOTC area.
• To characterize the iliac wing osseous corridor.
• To define the gluteal pillar osseous corridor for safe implant placement.

Main Methods:

• Computed tomography scans of 200 hemipelves (100 male, 100 female) were analyzed.
• Manual best-fit analysis determined cortical boundaries and IOTC.
• Iliac wing osseous corridor and gluteal pillar dimensions were measured.

Main Results:

• The IOTC is an elliptical area (22.3 cm²), with 48% of ilia showing unicortical convergence.
• The mean distance from the iliac crest to the IOTC was 20.3 mm (males) and 13.8 mm (females).
• The gluteal pillar averaged 5.3 mm (males) and 4.3 mm (females), insufficient for 5 mm implants in many cases.

Conclusions:

• A 4.5 mm lag screw is safe within 20 mm (males) or 14 mm (females) of the iliac crest.
• The gluteal pillar is smaller than previously assumed, posing limitations for larger implants.
• Findings enhance understanding of iliac osteology, guiding surgeons to safe implant placement areas.