This study evaluated the effect of angled Insertion of halo pins on the blomechanical characteristics of the halo pln-calvarlum complex. Halo pins were Inserted Into isolated calvarlum sections at 90deg;, 75deg;, and 60deg; to the surface of the bone at an Insertional torque of 0.68 N-m (6 inch-pounds). Initial rigidity, load at failure, and deformation at failure of the pin-bone complex were assessed during transverse shear loading. The structural properties of the pin-bone complex were maximized at loads approaching failure when pins were inserted perpendicular (90deg;) to the bony surface and significantly decreased at more acute angles of insertion. Perpendicular insertion of halo pins maximizes the structural properties of the complex formed by the halo pin and the calvarium. This Improved structural behavior may minimize the Incidence of pin loosening clinically, and may reduce the frequency of other complications currently associated with the use of the halo orthosls.
展开▼
