Laminectomy and Fusion - Clinical Tree

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Chapter Synopsis	Symptomatic cervical myelopathy from multilevel spinal cord compression in older patients is an increasing clinical problem. Multilevel anterior cervical surgical procedures carry significant morbidity. The posterior cervical approach reduces surgical morbidity. Although laminoplasty is often the surgical procedure of choice, laminectomy with spinal fusion and instrumentation is indicated in older patients who have significant neck pain and a K-line–negative or kyphotic cervical spine. This chapter describes the surgical indications for, contraindications to, pitfalls in, and tips for the successful execution of laminectomy and spinal fusion with instrumentation.
Important Points	Laminectomy and spinal fusion with instrumentation are indicated in patients who have three or more intervertebral disk levels of spinal cord compression and significant neck pain, spinal instability, and a K-line–negative or kyphotic cervical spine. Laminectomy and spinal fusion are indicated in patients presenting with cervical myelopathic symptoms, including clumsy hands and unsteady gait. Lateral mass screw placement is the surgical fixation technique of choice when compared with cervical pedicle screw fixation in most patients with cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament. Facet fusion is an important technique to ensure fusion in patients undergoing laminectomy and spinal fusion. The surgeon must ensure that cervical lordosis can be achieved before laminectomy, instrumentation, and fusion.
Surgical Pearls	To reduce the risk of junctional kyphosis, the surgeon should avoid muscle dissection at the C2 and C7 spinous processes by performing domelike osteotomy at C3 and partial cephalad C7 laminectomy. Removing the lamina en bloc instead of in pieces may reduce the risk of spinal cord injury by minimizing the frequency that the Kerrison rongeur is inserted into the stenotic spinal canal. When creating the gutter at the lamina-facet junction, the surgeon should angle the burr tip medially toward the lamina away from the facet to ensure a clean lamina cut. A number 4 Penfield instrument can be used to dissect the dural adhesion carefully from the undersurface of the lamina during en bloc removal of the lamina.
Surgical Pitfalls	During prone positioning, adequate space between the patient’s face and the Mayfield clamp must be ensured to avoid facial compression by the clamp. Overzealous use of shoulder tapes to depress the patient’s shoulders to improve the C6 to T1 fluoroscopic spinal image should be avoided because it may cause postoperative rotator cuff injury and brachial plexus injury. Recoil of the lamina can occur during the en bloc resection, with resulting iatrogenic spinal cord injury. Potential dynamic infolding of the posterior cervical muscle or postlaminectomy membrane into the spinal cord may result in postoperative spinal cord compression. Prophylactic bilateral posterior C4-C5 foraminotomies performed together with laminectomy and spinal fusion may reduce postoperative C5 palsy occurrence.

Surgical intervention is indicated in patients with symptomatic cervical myelopathy resulting from spinal cord compression. Direct anterior multilevel cervical decompression and spinal fusion with instrumentation carry significant surgical morbidity. To avoid these anterior surgical complications, indirect multilevel posterior surgical decompression techniques were developed. Posterior decompression allows the spinal cord to migrate posteriorly away from the offending anterior spinal cord lesions.

Multilevel laminectomies without spinal fusion and instrumentation should be avoided because they may result in postoperative kyphotic spinal deformity. Motion-preserving laminoplasty is often the technique of choice in the posterior cervical surgical approach; however, it is contraindicated in patients with a painful kyphotic spine or K-line–negative spinal alignment. Multilevel laminectomies and spinal fusion with instrumentation eliminate the micromotion of the kyphotic spine and have better postoperative clinical outcomes than does laminoplasty in patients with K-line–negative alignment. This chapter describes the surgical indications for, contraindications to, pitfalls in, and tips for the successful execution of laminectomy and spinal fusion with instrumentation. All laminectomy and spinal fusion techniques described in this chapter refer to laminectomy and spinal fusion with instrumentation.

Preoperative Considerations

Cervical laminectomy with fusion is a surgical technique designed for patients presenting with three or more levels of spinal cord compression associated with spinal instability resulting from various clinical conditions ranging from cervical spondylotic myelopathy (CSM), to cervical trauma to spinal metastasis. In general, these patients present with cervical canal stenosis with spinal cord compression, resulting in a clinical diagnosis of cervical myelopathy. The patient typically reports “clumsy hands” symptoms that cause difficulties in writing or performing fine motor skill activities. The patient also reports an unsteady gait or even frequent falls. Clinical examinations often reveal findings of upper motor neuron lesions and long tract signs. Of these myelopathic signs, Lhermitte sign, bilateral Hoffmann sign, inverted radial reflex, inability to complete a finger grip-and-release test (20 times in 10 seconds), positive Romberg test result, and failure to perform tandem gait are the most representative of cervical myelopathy.

Radiologic imaging to confirm the diagnosis of cervical myelopathy and for surgical planning includes radiographs, magnetic resonance imaging (MRI), and computed tomography scans. Anteroposterior and lateral upright radiographs assess cervical spinal alignment, which is essential for surgical approach planning. Flexion and extension lateral cervical spine radiographs exclude segmental spinal instability and confirm cervical lordosis in the extension film. MRI is the gold standard for the diagnosis of cervical canal stenosis and its pathologic features. Computed tomography is indicated to confirm the diagnosis of ossification posterior longitudinal ligament (OPLL) and ossification of the yellow ligament.

Controversies exist between the anterior cervical approach and the posterior cervical approach in the surgical treatment of cervical myelopathy. The principle of the posterior cervical approach is based on the indirect spinal cord decompression method. Posterior decompression and expansion of the spinal canal diameter allow the spinal cord to migrate posteriorly away from the offending anterior spinal cord lesion and result in indirect spinal cord decompression without direct removal of the anterior spinal cord lesion.

The success of the posterior cervical approach depends on the sagittal alignment of the cervical spine, and this approach is contraindicated in patients with a grossly kyphotic cervical spine. Various investigators have reported that the appropriate cervical sagittal alignment for the posterior surgical cervical approach ranges from less than 10 degrees of kyphosis to neutral sagittal alignment. Rao and colleagues suggested that the posterior approach is indicated if cervical lordosis is present in the lateral extension cervical radiograph.

Fujiyoshi and associates used a novel K-line concept, in which the K-line was defined as a line that connects the midpoints of the spinal canal at C2 and C7 in the sagittal view. OPLL that did not extend posterior to the K-line was described as K-line positive, and OPLL that extended past the K-line was termed K-line negative. The observed outcome of laminoplasty was better in K-line–positive patients. In a follow-up study, Fujiyoshi and co-workers further reported that laminectomy and fusion resulted in a better outcome than did laminoplasty in patients with K-line–negative OPLL. Taniyama and colleagues validated the K-line concept in patients with CSM.

In general, the authors prefer the laminoplasty technique for the posterior cervical surgical approach. However, laminoplasty is not without limitations. Liu and colleagues described the following reasons for the revision of laminoplasty procedures: significant axial neck pain, segmental kyphosis, and anterior spinal cord compression of more than 50% of the spinal canal. The authors’ current indications for laminectomy and fusion with instrumentation are in older patients, with three of more levels of spinal cord compression from conditions such as OPLL or ossification of the yellow ligament, who have K-line–negative sagittal alignment and significant axial neck pain.

Surgical Technique

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