Triple Major Curves

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.

Occasionally, the major curve (either the MT or TL/L) can be fused selectively while maintaining good balance of curves above and below. The instrumented curve must not be overcorrected to avoid throwing the shoulders off balance above or the trunk balance below.