JAPANESE MORPHOLOGIC CONSIDERATIONS FOR ILIOSACRAL SCREW PLACEMENT

Iliosacral screw placement has recently become a popular method of treat- ment for pelvic disruption fractures. It provides stable fixation that is biomechanically equal or superior to other techniques and requires less invasive surgery. However, recently, some iatrogenic complications have been reported, including radiculopathy of lumbo-sacral nerve, and arterial injury derived from miscannulation of screws in fluoroscopic image- guided procedures. The purpose of this stydy was to investigate the proximity of neurovas- cular structures in Japanese people to the first sacral (S1) body in which screws will be inserted. Twenty- five human Japanese cadavers were investigated. The distance to each structure was measured from the mid-point of the promontorium in the surface parallel to the S1 body. Latitudinal measurement was performed: X longitudinal: Y. The mean distances were as follows : 1.) L3: X, 43.7±9.0 mm, Y, 19.3±9.5 mm ; 2.) L4; X, 42.6± 12.1 mm, Y, 20.9±10.0 mm ; 3.) L5: X, 33.9±6.4 mm, Y, 24.5±9.0 mm ; 4.) internal iliac vein : X, 28.5±8.5 mm, Y, 7.4±7.5 mm ; 5.) internal iliac artery ; X, 28.7±10.4 m, Y, 5.5 mm±10.0 mm. These results suggest that if screws penetrate the sacral body, the L 5 nerve will be severely injured. Vascular structures will escape screw-related injury