Open technique for supra-acetabular pin placement in pelvic external fixation: a cadaveric study

Area of Science:

• Orthopedic surgery
• Trauma surgery
• Anatomy

Background:

• Standard supra-acetabular pin placement requires fluoroscopic guidance, posing challenges for untrained surgeons.
• Risks of open techniques without fluoroscopy for pelvic fractures remain under-investigated.
• The study aimed to compare open versus fluoroscopic techniques for supra-acetabular screw placement.

Purpose of the Study:

• To compare the open technique without fluoroscopy to the fluoroscopically assisted percutaneous technique for supra-acetabular screw positioning.
• To evaluate the safety and accuracy of freehand pin placement versus image-guided placement in cadavers.

Main Methods:

• 16 hemipelves from 8 cadavers were used, comparing open technique on one side with fluoroscopic guidance on the other.
• Schanz pins were inserted using specific angulations (medial 20°, cephalad 10-20°) in the open technique group.
• Dissection identified the lateral femoral cutaneous nerve (LFCN) and hip capsule, assessing pin penetration outside the bony corridor.

Main Results:

• The lateral femoral cutaneous nerve (LFCN) was in proximity (mean 15mm) in both groups; potential injury in the fluoroscopic group.
• Open technique showed less medial and cephalad inclination compared to fluoroscopic guidance.
• No joint penetration occurred with the open technique, versus one instance with fluoroscopic guidance; some extra-osseous penetration occurred in the open technique group.

Conclusions:

• The freehand technique, performed by experienced surgeons, is a viable alternative to fluoroscopic guidance for supra-acetabular pin placement.
• This technique may offer comparable safety and accuracy for stabilizing the anterior pelvic ring.
• Further research could explore its application in unstable pelvic fractures.