Posterior Fusion



- See: Crankshaft Phenomenon:

- Progressive Congenital Scoliosis:
    - fundemental procedure for congenital scoliosis is posterior spine fusion w/o instrumentation;
    - in young children correction of congenital scoliosis w/ instrumentation carries a higher risk of neurologic injury;
    - in older children w/ congenital scoliosis, instrumentation & correction of deformity may be done if tethering of spinal cord has been ruled 
           out;
    - posterior fusion is performed on both convex & concave sides of curve because arthrodesis performed only on convex side only tend to 
           bend with time;
           - the exception to this, however, is when a convex fusion is combined with hemi-epiphysiodesis;
    - anterior and posterior spinal arthrodesis:
           - indicated for deformities with known high risk of progression (such as concave bar with convex hemivertebrae);
           - curve correction occurs through the angulated vertebrae adjacent to actual congenital bar or hemivertebrae, & not through congenital 
                   deformity;


- Surgical Considerations:
    - Harrington distraction rods may be dangerous in congenital scoliosis, because of dysraphic problems;
          - distracting a tethered cord is likely to produce paralysis;
          - shortening of a long (convex) side of the curve can be preferable to lengthening of a short (concave) side;
          - use of subQ Harrington rod, which involves exposure of spine at ends of rod for hook insertion, has been successful when vertebrae 
                  adjacent to hooks are fused;
                  - rod must be distracted periodically (every six months) & spine must be braced until arthrodesis of the remainder of curve is 
                         performed when child is older (10 years of age or older);
    - crankshaft phenomenon
          - in skeletally immature pt, isolated posterior arthrodesis w/ instrumentation of a lordotic curve may act as a posterior tethering bar, 
                  producing lordosis & bending of the fusion mass as the unfused anterior vertebral bodies continue to grow



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Wednesday, April 25, 2012 12:29 pm