Degeneration of Disc and/or Facet Joint Surgery is rarely indicated for axial neck pain caused by degeneration of the disc and/or facet joint. However, if the source of the pain can be isolated to a specific motion segment, then a fusion of this segment may be beneficial. Stopping the motion of the painful segment can stop the pain from that segment. A combination of the history and physical examination, radiographs (including lateral flexion/extension), magnetic resonance imaging (MRI), and CT-bone scan SPECT (single-photon emission computed tomography) are used to identify the source of degeneration and pain (Fig. 43.1). Surgery is considered if the patient is having severe pain and limitation of function with activities of daily life (see Chapters 2, 3 and 6). Nonoperative care consists of medications, spinal injections, and chest-out posture exercises (see Chapters 4, 9, 13, 19, 37, 39 and 40).

A fusion will treat the pain from a degenerated disc and facet joint. However, a fusion may transfer stress to adjacent levels and increase pain and degeneration from those levels.¹ An artificial disc replacement may put less stress on adjacent levels, but may not treat facet joint pathology at the surgical level.

Radiculopathy Cervical radiculopathy presents with pain, weakness, and/or numbness in a radicular pattern into the arm. The most common causes are herniated disc and foraminal stenosis (Fig. 43.2). A majority of cases will resolve with time and conservative management (e.g., chest-out posture exercises, traction, epidurals, medications, and rest). Surgery is indicated if the pain is not resolving and/or there is a functional weakness of the extremity.

A fusion is the most common surgery performed for cervical radiculopathy because it most reliably treats an injured nerve root. The fusion surgery directly decompresses the nerve root, distracts open the
foramen, stops motion and irritation of the nerve, and treats disc and facet joint pathology. The downside to a fusion is increased stress on adjacent levels, which may increase degeneration on adjacent levels.

By preserving motion of the disc, an artificial disc replacement may decrease stress on adjacent levels compared to a fusion² (Fig. 43.3A and B). An acute, soft tissue disc herniation may be safely removed anteriorly and replaced with an artificial disc replacement. However, if the motion segment has significant underlying degeneration and osteophytes, the artificial disc replacement may not adequately treat the pathology in the long term. Osteophytes resorb after fusion because of the stoppage of motion. Furthermore, local kyphosis of the motion segment is a relative contraindication for an artificial disc replacement because the disc will typically fall back into kyphosis with the prosthesis. However, a fusion can correct the kyphosis and maintain the improved alignment, which can decrease stress on adjacent discs because the weight of the head is not anterior.

Posterior foraminotomy is another option to treat cervical radiculopathy.³ Up to 50% of the facet joint can be removed while still preserving stability of the segment. This surgery is particularly effective if the compression of the nerve root is from facet joint hypertrophy (Fig. 43.4). A soft tissue herniated disc may also be removed from this approach. However, removal of the disc herniation does require retraction of the nerve root and/or spinal cord, which may result in neurologic injury. A foraminotomy has the best prognosis when a patient has mechanical radiculitis preoperatively, as indicated by a positive shoulder abduction test (relieves the pain) and a positive Spurling maneuver (provokes the pain). A foraminotomy may not entirely relieve the symptoms or the symptoms may return because of preservation of the degenerative motion segment.

Myelopathy Cervical myelopathy may present with upper and/or lower extremity findings. Upper extremity myelopathy is caused by spinal cord compression at C3-4 or above (which is where the cell bodies for C5-C8 are located). Upper extremity myelopathy presents with clumsy hands (difficulty with buttons), difficulty with rapid hand movement, positive Hoffman test, and hyperreflexia of the upper extremities. Lower extremity myelopathy, because of cervical or thoracic spinal cord compression, presents with hyperreflexia, clonus, positive Babinski sign, and gait disturbance (broad-based gait with heel-to-toe walk).

Typically, surgery is indicated when there is spinal cord compression causing myelopathy (Fig. 43.5). The risk of not doing surgery is progression of neurologic dysfunction. The type of surgery depends on location of compression, presence of instability, overall alignment, concurrent radiculopathy, degree of degeneration, and pain.⁴ If the compression is anterior from a disc herniation, then an anterior discectomy and fusion is typical. Multilevel anterior fusions in the elderly have a high incidence of dysphagia and nonunion. Alternatively, the decompression can be performed posteriorly. Posterior surgical options include laminectomy, laminoplasty, and laminectomy with posterior fusion. Cervical laminectomy may result in postoperative kyphosis because of loss of posterior tension band and support. Cervical laminoplasty preserves the posterior arch of bone and has been shown to have less risk for postoperative kyphosis. Patients with severe axial neck pain may fare better with a fusion than a laminoplasty because the fusion may decrease the neck pain resulting from the degeneration. Posterior cervical laminectomy with fusion has the risk of failed fusion or adjacent level degeneration.

Degeneration of Disc and/or Facet Joint Axial pain from thoracic degenerative disc and facet joint disease is not typically disabling because the rib cage provides inherent support to this region. The underlying lack of motion of these segments makes a fusion less likely to decrease pain, as compared to the mobile cervical and lumbar regions. If the source of pain can be localized to a specific motion segment with diagnostic studies such as MRI, bone scan, CT scan, diagnostic nerve blocks, and radiographs, then a fusion may be helpful.

Radiculopathy Thoracic radiculopathy may be caused by a disc herniation, facet joint pathology, or stenosis. MRI is the most helpful diagnostic tool. An intercostal nerve block may help with nonoperative treatment and confirm preoperative diagnosis. Typically, disc herniations and severe facet joint pathology are surgically removed while performing a fusion. The fusion allows wide decompression of the bony elements with less risk of spinal cord trauma. Laminectomy may be performed for central stenosis if the stability of the facet joints can be preserved.

Myelopathy Thoracic spinal cord compression causing lower extremity myelopathy may be caused by a disc herniation, facet joint pathology, or ligamentum flavum stenosis (Fig. 43.6). Surgery involves removing the offending structure and then fusing the segment if there is resulting instability. Thoracic disc herniations may be removed from a lateral approach through the chest cavity or posteriorly after removing a facet joint. Typically, either approach is combined with a fusion.

Degeneration of Disc and/or Facet Joint Similar to the cervical spine, determining the exact source of axial lumbar spine pain can be difficult. A thorough history and physical examination combined with diagnostic studies such as radiographs (anteroposterior, lateral, flexion and extension), MRI, and CT-bone scan SPECT can localize the pain to specific structures such as the disc or facet joints (Fig. 43.7A). The success of surgical intervention depends on the odds the correct
pain generator has been determined, the ability of the surgery to be done safely with minimal soft tissue trauma, and the postoperative rehabilitation program.

Surgery is considered for patients suffering from chronic pain and limitation of function despite medications, spinal injections, and completion of a trunk stabilization program. Fusion surgery for degenerative disc disease has been shown to have an approximately 70% to 80% success rate in significantly reducing pain and increasing function. Typically, preoperative pain of 7 out of 10 can be reduced to 4 out of 10 postoperative. It is important that patients have a realistic expectation from the surgery, specifically that the average postoperative pain is still a 4 out of 10.⁵ The reoperation rate of an adjacent level that develops degeneration after a fusion is approximately 15% by 10 years.⁶

With degeneration of a disc, the motion segment loses disc height and lumbar lordosis. This places more stress on adjacent discs by shifting the weight of the torso anterior, which can increase the rate of degeneration naturally. A fusion operation stops the motion of the segment (which stops the pain from that segment), transferring motion and stress to adjacent segments. If the motion segment is fused in the collapsed and kyphotic position, this may further increase the stress on adjacent levels.⁶ If the fusion operation successfully corrects the loss of disc height and restores lumbar lordosis, this will place less stress on adjacent segments by shifting the weight of the torso posterior (Fig. 43.7B). In summary, the fusion operation increases stress on adjacent levels by stopping the motion of the surgical level, but it may decrease stress on adjacent levels by correcting
lordosis and shifting the weight of the torso back over the pelvis.