A, Supralaminar hook insertion. This insertion applies to lower two concave hooks in single thoracic curve instrumentation. Laminotomy is kept as small as possible to minimize risk of deep penetration into spinal canal during rod insertion. Tight fit is necessary, and thoracic laminar hook is used if laminar thickness is too small to allow lumbar laminar hook to be stable in anteroposterior plane. B, Infralaminar hook insertion. Lower convex hook in right thoracic curve is inserted in this manner. Ligamentum flavum is dissected off underside of lamina. Small inferior laminotomy provides horizontal purchase site for hook. Adjacent facet capsule should be spared because it is not included in fusion. SEE TECHNIQUE 44.13.