Re: help! need advice
Rods may break if there is an area of non-union of the fused area of the spine, because the micro-movements caused by this non-union puts tiny amounts of stress of the rod which can eventually lead to metal fatigue. This is rare but it does happen. It was more common with the old-style Harrington Rods as they were only attached to the spine at he ends of the rod so weren't as secure as modern instrumentation (this is why Harrington patients always wore casts or braces post-op, until their fusion was looking secure).
37 years old, diagnosed with infantile idiopathic scoliosis at 6 months old with curves of 62(T) and 40(L) degrees. Casting and Milwaukee braces until surgery at 10 - ant release/pos fusion T1-T12, halo traction. Post op cast and then TLSO. Further surgery at 18 (ant release/pos fusion extended to L3 to include lumbar curve, costoplasty) and 25 (another costoplasty). Fusion extended to L4 at 33 (XLIF with 4 pedicle screws and two short rods). Pre-op curves: 76(T) and 70(L). Post-op curves: 45(T) and 35(L). Diagnosed with Ehlers-Danlos Syndrome aged 34; scoliosis almost certainly due to this rather than being idiopathic.