(based on classification of
King et al) assistance provided by Ben Allen Jr. M.D.
- See:
Selection of Fusion Level:
- Discussion: - "S" shaped
thoracolumbar curve crosses midline; - thoracic curve is larger and stiffer than lumbar curve; - selective arthrodesis of the thoracic curve in King type II curves may lead to larger residual lumbar and loss of balance; - over correction of main thoracic curve may be one of problems, because in
lumbar curve, spontaneous correction is not sufficient to restore balance; -
treatment: - the goal w/ this type of curve is to preserve lumbar lordosis along w/ a motion segment; - usually w/ flexible curves less than 45 deg, lumbar fusion can be limited to L3 or higher; - distally the up-going convex lumbar hook and the down going concave hook are placed at the same level; -
convex lumbar curve: - down going proximal hook and up going distal hook; -
concave lumbar curve: - down going distal hook, at same level as convex distal hook; -
concave thoracic curve: - down going distal hook (which is also the down going hook of the upper lumbar curve; - up going hook at apex of the curve; - up going hook above end vertebrae; -
convex thoracic curve: - up going hook at apex of curve which is staggered from the apex concave up going hook - up going hook above proximal end vertebrae, which is staggered from opposite concave hook; - if the shoulder is high on the concave side, then the convex up-going hook is placed one level caudad relative to the concanve hook; - w/ severe asymmetry, the hook is placed two levels caudad; - note: distraction on the concave side may elevate the ipsilateral shoulder; - in this case, the shoulder will be low on the concave side, and therefore, the convex up-going hook is placed on level cephalad relative to the concanve hook; - w/ severe asymmetry, the hook is placed two levels cephalad;
