For type 4 TM curves, the general rule is to fuse all three regions. Either the MT or TL/L region can be the major curve, but all three regions are structural.
These curves usually require instrumentation and fusion posteriorly of all three regions from T2 to T3 above, down to L3, or L4 below.
Also quite common pattern in Idiopathic Scoliosis, 80% occur on the right side.
For type 5 TL/L curves, the general rule is to fuse only the TL/L region, either anteriorly or posteriorly, or, rarely, circumferentially, if required. Anteriorly, the fusion levels will usually be the upper end vertebra, and posteriorly from either the upper end vertebra or one above that to the lower end vertebra or one below that.
Traditionally, these curves have been treated with a selective similar corrections for these curves being obtained through a posterior-only appraoch, as recently reported by Shufflebarger and associates. Rarely, both the MT and TL/L regions require fusion, especially if the shoulder balance requires correction of the MT curve, or the thoracic rib hump is such that inclusion of the MT curve would be required, especially in highly skeletally immature patients with significant growth remaining.
Scoliosis Thoracolumbar Curve