Accuracy of Supra-acetabular Schanz Pin Insertion Using a Finger-Assisted Technique: A Cadaveric Study

Abstract

Purpose: External pelvic fixation is an essential procedure for stabilizing unstable pelvic fractures. Supra-acetabular pin placement provides greater biomechanical stability than the supra-iliac crest technique, but it is technically more demanding and typically requires fluoroscopic guidance, which may be unavailable in urgent or resource-limited settings. In this study, we aimed to evaluated the accuracy of a finger-assisted technique for guiding supra-acetabular Schanz pin insertion without fluoroscopy.

Methods: This experimental cadaveric study included 18 fresh-frozen cadavers (36 hemipelves). Six orthopedic residents experienced in external pelvic fixation using sawbone models underwent training to perform the finger-assisted technique. Each resident performed the procedure on three cadaveric pelves (six hemipelves). After pin insertion, all the specimens were dissected using an iliofemoral approach. Pin position and complications, including hip joint penetration, lateral femoral cutaneous nerve injury, and intra-abdominal organ injury, were recorded.

Results: Of the 36 supra-acetabular Schanz pins inserted, 33 were completely intraosseous, yielding an accuracy rate of 91.7%. Three pins (8.3%) were malpositioned: two breached the medial cortex of the iliac wing, and one penetrated the hip joint. No visceral or lateral femoral cutaneous nerve injuries were observed.

Conclusions: Supra-acetabular external fixation using a finger-assisted technique is a useful alternative for guiding Schanz pin insertion, particularly in resource-limited settings.