This week’s Case Debate Series, hosted by NuVasive, Inc., features complex spine and raises several important questions regarding material, procedure, and tethering as part of a distributed loading technique. Dr. Zachary Tempel, neurosurgeon at Mayfield Brain and Spine, provides a very thoughtful discussion of intraoperative rod technique while also highlighting material selection and construct configuration. Dr. Jeff Mullin, a neurosurgeon at University at Buffalo Neurosurgery, leans toward the materials and specifically highlights load distribution tethers while also mentioning an intraoperative weave technique. Dr. Reg Haid of Atlanta Brain and Spine Care referees this lively debate.
Moderator Haid: This is our second of our Case Debate Series hosted by NuVasive. We’d like to thank our industry sponsor and partner NuVasive for their help.
We’re going to hear a couple of peers discuss, debate, and talk about the pros and cons of procedural approaches and the application of technology. Today’s debate is going to be about creating a softer landing in our long fusion constructs, its complex spine and distributed loading techniques and all about a gradual change in stiffness for a soft landing for long constructs.
We have a couple of exemplary young spine guys. The first is Zachary Tempel, a neurosurgeon at the Mayfield Brain and Spine in Cincinnati, Ohio. Jeff Mullin is a neurosurgeon and assistant professor at the University of Buffalo. Let’s start with Dr. Tempel.
Dr. Tempel: I think this is an interesting topic. Rod stress and demand is not the same throughout a construct. The optimal degree of stiffness required where the correction happens is not the same as what’s necessary at the top of the construct, which is why we place additional rods across a pedicle subtraction osteotomy or other points of stress. It doesn’t make sense to prescribe the same universal rod, stiffness, or material to a construct and then have it abruptly transition to normal anatomy. How do we transition from a highly rigid construct to a less rigid construct while minimizing the disruption of normal anatomic structures?
For the majority of my deformity operations, I combine multiple materials of various stiffness to transition across the construct. I’m trying to be more accurate with how I prescribe a material based on the location of the construct and the corrective goals.
The first case is a 70-year-old male with Parkinson’s who had pseudarthrosis and failure after an L2-5 TLIF done at another hospital. We did a single-level lateral interbody fusion at the L1-2 level and extended the fusion up into the lower thoracic spine and also fixed the focal coronal deformity there. We ran a parent rod from T12 down to the pelvis, which was a 5.5 mm cobalt rod. We used separate 5.5 mm titanium rods to span T10-11. We bridged that gap in this case with another 5.5 mm cobalt rod and side-to-side connectors to link in the two constructs together. And the goal here is to provide a little bit extra give at those top two segments in hopes that this reduces the stress on the adjacent segments. With a technique like this, there’s no laminar work done at the UIV plus one, and no disruption of the posterior ligamentous complex. It works out nicely.
This next case is a 70-year-old woman with adjacent segment generation, severe foraminal stenosis above a unilateral construct and focal scoliosis. She needed a little bit of correction, which we were able to achieve with the 15-degree lateral cage and extension of her fusion up to T9. Rather than use the side-to side-connectors, we used dual-headed pedicle screws to accommodate an outrigger rod from T11 down to the pelvis. The parent rod consisted of 5.5 mm cobalt and a separate 5.5 mm titanium rod at T9-10 connected with 5.5 mm titanium outrigger rods.
