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Type A & B for the distal fusion levels. Thoracic curve type A; the neutral vertebra (NV) is located 1 level distal from the end vertebra (EV), fuse to the NV. Thoracic curve type B; the NV is located 3 levels distal from the EV, fuse to the NV-1. Lumbar curve type A; L3 cross the central sacral line and rotation is less than G2, fuse to the L3. Lumbar curve type B; L3 not cross central sacral line and rotation is more than G2, fuse to the L4
