8. Documented instability at the level on flex/ext views – >4mm translation, > 10 degrees of angulation.
Intraoperative Structural Alterations
– taking >50% of the facet – the motion segment is unstable and should be fused.
– taking the disc out – aggressive discectomy renders the anterior column unstable and should be fused
The addition of instrumentation – also a controversial thing!
– Consider adding instrumentation when: 1. Correcting deformity. 2. Fusing more than one motion segment. 3. Treating recurrent stenosis and iatrogenic spondylolisthesis. 4. Documented instability preoperatively.
– the addition of pedicle screws to a single level degenerative spondy has been shown (Fishgrund) to improve fusion rates, but this had no effect on patient outcome.