Diam was one of a huge crop of interspineous devices that came out several years ago. Wallis, X-Stop, Diam, Coflex, ISS, Wellex, Dynafix, Spineos, BacJac, In-Space, Superion and I'm sure there are others that don't come to mind right now. Diam was somewhat different because it is a soft silicone spacer that is designed to support the posterior elements.
When I first saw Wallis, I think back in 2004, I thought that it would keep most of us from having ADR. If you could do a discectomy and somehow jack up the disc space, offload the posterior annulus (where so much of our low back pain is generated), and stabilize the system with a minimally invasive surgery, what could be better?
5 years later, I'm still waiting for the flood of data and the rush to do this. I've observed Wallis and Coflex procedures. It does seem to be relatively small compared to ADR, but the philosophy is completely different. These devices are designed to take away motion, whereas ADR is designed to restore motion. With these devices, you will not address discogenic pain. Originally the theory was that offloading the posterior annulus would relieve the stresses that were painful, but I think that pans out in only a small percentage of the cases. If you leave all the painful tissues and put a rock between the very back of the system, I think the disc may still continue to collapse (now with a kyphotic alignment). With sagittal balance off and motion severely limited, what does that do to the adjacent levels?
Also, I don't believe that these devices are appropriate for L5-S1 and that is almost 1/2 of lumbar disc disease.
Having said that, I believe that X-Stop and other devices have been very effective at dealing with typical old person's stenosis. The folks who get leg pain when they stand up, and have to walk leaning forward seem to get great relief from the interspineous devices. It basically forces just the level with the stenosis into flexion and offloads the structures that cause more buckling of the ligamentum flavum that lights them up when they stand or go into extension.
It's all about indications. They are different for ADR, dynamic stabilization, interspineous devices, etc... The proponents of the devices tend to over use them across too many indications.
I have to go now... This is all off the top of my head... I'll look some things up and post later.
Mark
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