Jeff discussed this well and I’d like to refer you to the excellent work of Justin Smith. You can Google that and just look at several of his articles.
We also talked about the new sublaminar tethers or spinous process tethers. If you use a spinous process tether, it preserves the muscular envelope. If you do a sublaminar tether, you’re doing deeper denervation of the posterior muscles.
To use a matchstick and then a tenaculum at the base of the spinous process, you have to go to where the spinous process hits the lamina. If it’s too high in the spinous process it will fracture. You want to use the matchstick and the tenaculum closer to the lamina and do a weave pattern one and two levels above preserving the posterior musculature.
If you use a 3.5 mm titanium rod, you’re still having to denervate by placing screws or hooks. I think Zach is extremely thoughtful when he talks about changing the stiffness of the longitudinal construct. If you can combine the best of both worlds you would have stiffer, stronger rods where you need to correct and maintain correction of the deformity, particularly down low or the apex of the curve or after an osteotomy. You can diminish that stiffness based upon diameter and material. We’ve used peek rods for years and designed peek rods used in Europe now for lumbar areas. The peek rods have not panned out as much as people like.
I think this discussion was simply excellent. Pay particular attention to the technique of tethering. We all have to do a bit more studying to determine what is the optimal rod construct and whether you change the longitudinal members or not. I think we’re still trying to figure that out.
Gentlemen, I think you’ve done an excellent job of this, and I like to congratulate you. Thank you.
