Effects of Screw Length on Spine Reconstruction Studied
Study finds short screws as strong as long screws if augmented by bone cement
TUESDAY, Dec. 22 (HealthDay News) -- In treating spinal disorders that require spino-pelvic reconstruction, short screws have similar biomechanical strength as long screws if augmented by bone cement, according to a study in the December issue of the Journal of Spinal Disorders & Techniques.
Using pelvis specimens from human cadavers, Zhao-Min Zheng, M.D., and colleagues from the First Affiliated Hospital of Sun Yat-sen University in Guangzhou, China, placed short and long iliac screws on either side of the pelvis, or placed short screws after augmentation with polymethyl methacrylate bone cement on one side and the long screw on the other side.
After fatigue loading to each screw, the researchers found that the maximum pullout strength was significantly higher for the long screw (2,386 versus 833 N). However, after applying the bone cement to the short screw, the pullout strengths were similar for the short and long screws (2,436 versus 2,529 N).
"Short iliac screws are susceptible to loosening after cyclic loading," the authors write. "Bone cement augmentation of short screws has demonstrated a significant increase in the fixation strength of short screws to an extent similar to that of long iliac screws."