time for subsidence risk to show up

[herniated C6-7]

I'm thinking seriously of going abroad for ADR. But I'd like to know more about subsidence risk--the risk that the artificial replacement disc moves out of place.

I have a lot of bony growth near C 6-7 which will have to be removed during ADR surgery. My US surgeon told me that surgical removal of the bony growth could weaken my bone structure and increase subsidence risk. I've been checked for osteoporosis and my bones are fine right now.

Does anyone know how long subsidence, if it's going to happen, takes to show up post-ADR surgery? If I went to Germany for ADR surgery, for example, would it be most prudent to remain in the area for some weeks or even months afterwards?

Does anyone know what percentage of ADR patients suffer subsidence and whether the number is different for cervical or lumbar ADR?

I was impressed to read on the Stenum web site that Dr. Ritter-Lang has experienced zero incidence of subsidence in his past 100 lumbar ADR surgeries using the M6. Does anyone know if Ritter-Lang has had like success in reducing subsidence risk for cervical ADR patients? The Stenum site says that Ritter-Lang has been using the M6 for 3 years. Is that a long enough time frame for evaluation of subsidence risk?

The Stenum web site reads as if that success in attaining zero incidence of subsidence owes much to the M6. My US surgeon said it would not be due to the artificial disc used, but to the skill of the surgeon. Any thoughts on that issue?

[trkdoc714]

I'm thinking seriously of going abroad for ADR. But I'd like to know more about subsidence risk--the risk that the artificial replacement disc moves out of place.

I have a lot of bony growth near C 6-7 which will have to be removed during ADR surgery. My US surgeon told me that surgical removal of the bony growth could weaken my bone structure and increase subsidence risk. I've been checked for osteoporosis and my bones are fine right now.

This is a subject to be covered when you interview the surgeon. Depending on the device chosen, there may or may not be a need to remove all or even some of the boney growth.

Does anyone know how long subsidence, if it's going to happen, takes to show up post-ADR surgery? If I went to Germany for ADR surgery, for example, would it be most prudent to remain in the area for some weeks or even months afterwards?

I don't have an answer to that question. It may be difficult to answer due to the various designs of discs. The only documented cervical subsidence I'm aware of has to do with a 3 level ProDisc procedure. A bone infection was blamed for the subsidence. Whether the infection was present prior to surgery or if it was transmitted during surgery is unknown. Keeled devices require removal of bone via chiseling or drilling a groove into the vertebrae. This might allow bacteria to infect the bone and weaken its integrity. The grooves can also weaken the natural structure of the bone and could also be the cause of subsidence.

Does anyone know what percentage of ADR patients suffer subsidence and whether the number is different for cervical or lumbar ADR?

I think subsidence is relatively low in ADR surgeries. Most surgeons are very careful in qualifying their patients and bone density/ risk of subsidence is high on their list of contraindications of ADR candidates. The risk of subsidence lowers with time and bone growth.

I was impressed to read on the Stenum web site that Dr. Ritter-Lang has experienced zero incidence of subsidence in his past 100 lumbar ADR surgeries using the M6. Does anyone know if Ritter-Lang has had like success in reducing subsidence risk for cervical ADR patients? The Stenum site says that Ritter-Lang has been using the M6 for 3 years. Is that a long enough time frame for evaluation of subsidence risk?

The M6 is not a keeled device. As no bone is removed from the vertabrae, the structural integrity is left intact. Dr. Ritter-Lang is a highly skilled surgeon as well. The lumbar discs he implanted in my spine are as perfectly placed as can be.

The Stenum web site reads as if that success in attaining zero incidence of subsidence owes much to the M6. My US surgeon said it would not be due to the artificial disc used, but to the skill of the surgeon. Any thoughts on that issue?

My opinion is both factor into a successful outcome.

[herniated C6-7]

I'm not sure what the previous post means when it says that the M6 is "not a keeled device". The Spinal Kinetics web site describes the M6 as "tri-keeled" and the photo shows at the end of the M6 three projections or keels. Instrumentation for the M6 include tools for cutting keel tracks. Perhaps it is more accurate to describe the M6 as having a different sort of keel. But unless I'm misunderastanding the Spinal Kinetics web site, insertion of the M6 still requires cutting into the bone to secure the artificial disc and titanium endplates.

[trkdoc714]

In comparison to the ProDisc and Maverick discs, the keels on the M6 require less material removal/ displacement. From my understanding the bone is grooved with a chisel but are shallow grooves unlike the Synthes and Medtronic discs which require a deep channel chiseled or drilled into the bone.

Terminology aside, the keels on the M6 have less potential for damaging the vertabrae while increasing stability with the use of 3 shallow keels.