San Francisco Spine Surgeons

Procedures San Francisco Bay Area

Bone Graft

Bone graft is the material that is used to promote fusion or adjoining several vertebrae together. It can come from the patient himself (autograft) from another human (allograft) or another species, such as coral (xenograft). Also, a bone graft extender can be utilized, in which case it does not come from any living organism and is purely synthetic. Occasionally we utilize synthetic protein, which is a growth factor called bone morphogenetic protein (BMP-2 or INFUSE). It is a growth factor that promotes bone formation and has been successfully used in clinical application anywhere from skull to spine and extremities in the past decade or so. Depending on the procedure, the patient’s preferences, as well as the patient’s medical history (such as smoking, diabetes, and history of prior surgeries), the surgeon may choose one or more from the above. Another option for bone grafting involves drawing bone marrow from the iliac crest or vertebrae and hyperconcentrating it to yield concentrate of the stem cells. Derived from the patient himself, the stem cells are known as pluripotent, meaning that they are able to mature into multiple types of tissue. In the case of spine surgery, the goal is to promote maturation of the stem cells into bone-forming cells (osteocytes and osteoblasts). We have successfully utilized a bone marrow aspirate concentrate system (BMAC from Harvest) at St. Mary’s Spine Center for more than a year, with excellent clinical results. The main advantage of bone marrow aspirate concentrate is decreased morbidity of the bone graft harvest.

Cervical Total Disc Replacement (TDR)

We have been using cervical total disc replacement at St. Mary’s for a number of years. We have been one of the investigational sites as part of the IDE trials for a number of disc replacements prior to their approval for widespread clinical use. Currently, we favor ProDisc-C and LDR total disc replacements both for single-level and multilevel implantation. The main premise of total disc replacement in the cervical spine is (1) preserving natural motion in the cervical spine, and (2) minimizing or avoiding adjacent-segment degeneration. Additionally, several clinical studies have demonstrated decreased chance of reoperation. At the present time, total disc replacement has emerged as a “gold standard” for treatment of a number of degenerative spine disorders. It is used in addition to anterior cervical discectomy and fusion, and in some cases the same patient will undergo total disc replacement at one level and anterior cervical discectomy and fusion at another level to create a so-called hybrid construct.

Cervical Myelopathy

In the lumbar spine, the nerves to the lower extremities, bowel, and bladder pass through the spinal canal in a new sac filled with spinal fluid. In the neck, instead of the group of nerves passing through, the spinal cord makes its way from the brain all the way down to the L1-2 lumbar level, where it stops, continuing on as individual nerves below that point. As in the lumbar spine, individual nerves leave at each joint in the neck, in this case to go to the arms or upper trunk area.

“Snake eyes” appearance of myelomalacia on MRI.
When an abnormal condition causes too much pressure on the spinal cord, the spinal cord’s ability to transmit signals becomes compromised, and certain physical findings and disability occur. When complete loss of function occurs, paralysis of the upper and lower extremities results, depending on the level of the compression. When the spinal cord is not functioning properly due to disease processes such as compression or degeneration, cervical myelopathy develops. The initial signs of this include abnormal reflexes, poor balance, numbness in the upper extremities, electrical sensations in certain neck positions usually radiating down the body or arms, and increased urinary frequency. Increasing severity can result in partial or complete paralysis of the extremities and loss of sensation below the site of the compression. Because the spinal cord does not heal as well as individual nerves after they have passed through the spinal cord, timely correction can be more crucial when the spinal cord compression is surgically correctable. Because of this, when we as spinal surgeons see signs of decompensation in spinal cord function, we will arrange to repair the problem as quickly as reasonable. Delays can result in permanent weakness or paralysis of upper and/or lower limbs.

Cervicothoracic Fusion for Cervicothoracic Deformity and Longer Constructs

Occasionally it is necessary to fuse both part of the cervical spine as well as thoracic spine together. This is usually done from the back (posterior approach). The cervical part is very similar to the posterior cervical laminectomy and fusion. After the posterior aspect of the spine is reached, bone screws are inserted in the neck. Normally, we utilize lateral mass screws in the cervical spine at C3, C4, C5, and C6, with pedicle screws at C7 and C2. Then, pedicle screws are inserted in the upper thoracic spine, and the screws both in the neck and the thoracic spine are connected by rods. Those are held place with said screws.

Highly unstable fracture at cervico-thoracic junction in a patient with ankylosing spondylitis.
Surgery – posterior cervical fusion, lateral mass and pedicle screws.

At times, corrective osteotomy is necessary, usually at C7, especially for cases of when the head “falls” forward (cervicothoracic kyphosis or dropped-head deformity). A procedure like this normally takes anywhere from four to six hours, frequently done with neurological monitoring and use of a surgical microscope. Postoperatively, patients frequently require a stay in the intensive care unit for at least one night. The hospital stay ranges anywhere from three to seven days.

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For bone graft, cervical total disc replacement, cervical myelopathy, and cervicothoracic fusion services in San Francisco, CA.

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