I had the pleasure of meeting with one of our local orthopedic surgeons, Dr. Benjamin Bjerke, and the Zimmer-Biomet rep, Christina Escobar, to talk Mobi-C Disc Replacement technology and surgical technique developed by Zimmer-Biomet. Incredibly interesting.
Seeing the prosthesis, my first question was, “Is this a model or the real thing you are showing me?” It was much smaller than I anticipated!
Secondly, I found the specificity of the patient suitable for this intervention impressive – someone with neck pain and or radiculopathy (pain down the arm originating from nerve root compression in the neck) without much cervical spondylosis (degeneration of the discs and joints in the neck) and good vertebral alignment. The Mobi-C can replace discs at one or two levels of the cervical spine between the third and seventh cervical vertebrae.
So lets take a look in more detail.
Anatomy and Pathology of the Neck
- The cervical spine has discs between each bone that provide cushioning for movements and body loads. The discs and bones in a healthy neck allow bending from side-to-side and front-to-back, and turning left-to-right. Disc problems can start from over-use, an accident, or just the wear and tear of daily life. When a disc degenerates it becomes thinner and provides less padding to absorb movement. Degenerated discs can also bulge (herniate) and pinch the spinal cord or nerves, which causes loss of feeling, weakness, pain, or tingling down the arms and hands. Below you can see the normal cervical spine anatomy and adjacent is a graphic of what a spine with pathology may look like:
- Before artificial discs were available, patients would traditionally receive an Anterior Cervical Discectomy and Fusion procedure to alleviate the pain from a herniated disc. In a fusion surgery, the disc is removed and either a bone spacer or a plastic implant is placed in the disc space to restore disc height and remove pressure on the pinched nerves or spinal cord. A metal plate and screws is placed on the front of the vertebral column to hold the implant in place. The result – a segment that no longer moves, or is “fused”. The potential downside of a fusion procedure, in addition to the loss of motion, is that it can create additional stress on the spinal levels above and below it. This can cause degeneration at those levels and potentially result in another future surgery.
- An artificial disc like Mobi-C is an option instead of a fusion that will also be placed inside the disc space to restore height and remove pressure on the pinched nerves. However, the Mobi-C device is designed to allow the neck to maintain normal motion and thus limit adjacent levels from degenerating, possibly preventing future surgeries.
Since Mobi-C cervical disc replacements are preferred over fusions because they preserve movement in the spine, lets take a look at this video to see what happens in the spine when a patient with the Mob- C implanted flexes and extends his/her neck versus a two level fusion:
Cervical disc replacement procedures are anticipated to experience rapid growth in the near future, due to multiple factors:
- A growing library of clinical evidence demonstrating the long term safety and efficacy of cervical disc replacement.
- Cervical disc replacement is being shown as a superior treatment to fusion for use at two cervical levels.
- Better outcomes of cervical disc replacement over fusion such as reduced re-operation rates, reduced adjacent segment degeneration rates and surgeries, as well as a faster return to work.
- Most patients return to work within six weeks of surgery. In the U.S. Mobi-C clinical trial, the return to work time was 20.9 days shorter for Mobi-C patients compared to fusion patients for two-level surgery and 7.5 days shorter for Mobi-C patients compared to fusion for one-level surgery.
What about physical therapy after the Mobi-C disc replacement?
- Wear a neck collar to lessen neck movement for around a week after the surgery.
- Avoid heavy lifting, repetitive bending, and prolonged or strenuous activity for up to 6 weeks after surgery.
- When your surgeon releases you to start physical therapy the physical therapist will do a comprehensive evaluation to assess your cervical, scapular and shoulder range of motion as well as cervical, arm and trunk strength. Based on the data collected, you will be given specific exercises to address any deficits to ultimately improve your function. You may start of with cervical isometrics and progress to upper thoracic and arm strengthening exercises as well as neuromuscular reeducation of the deep neck muscles. The physical therapist will also utilize soft tissue mobilization techniques to limit scar formation and address any myofascial pain and muscle trigger points, present from inactivity. You will need to participate fully by being totally compliant with the home exercise program you are given by the physical therapist at your very first visit.
Successful outcomes are determined by multiple factors which include choosing the right surgical procedure done by a skilled surgeon, following post operative activity limitations and brace use as well as being totally compliant with physical therapy instructions and exercises. It is a 3 person team that makes your recovery work: you (and your home supporters), the surgeon (and their staff) and the physical therapist (and their clinical team members).