History of Instrumentation for Stabilization of the Subaxial Cervical Spine

Ibrahim Omeis, M.D.; Joseph A. Demattia, M.D.; Virany Huynh Hillard, M.D.; Raj Murali, M.D.; Kaushik Das, M.D.

Disclosures

Neurosurg Focus. 2004;16(1) 

In This Article

Posterior Cervical Instrumentation

The first recorded surgical instrumentation of the cervical spine dates back to 1891 when Dr. Berthold Earnest Hadra (Fig. 1) performed an internal operative spine immobilization by wiring together the spinous processes of the sixth and seventh cervical vertebrae.[16] Later Hadra applied this technique to correct the deformity associated with Pott disease. This surgical procedure came to the attention of European orthopedists who made modifications and continued its use. Over the past several decades, numerous methods have been developed to stabilize the spinous processes, laminae, and pedicles of the cervical spine.[6,7,8,9,22,28] These methods include wiring (interspinous, facet, and interlaminar clamping) and application of lateral mass screws and plates, lateral mass screws and rods, and cervical pedicle screws.

Photograph of Berthold Earnest Hadra. From Keller T, Holland MC: Some notable American spine surgeons of the 19th century. Spine 22: 1413-1417, 1997; reprinted with permission from Lippincott-Raven.

Rogers initially described the interspinous wiring technique for the treatment of trauma-induced cervical instability in 1942.[28] This technique involves drilling holes into the spinous processes and passing wires through them (Fig. 2). Whitehill, et al.,[33] Benzel and Kesterson,[6] and Murphy and Southwick[25] have described modifications of this technique, but the fundamentals remain unchanged.

Lateral (left) and anteroposterior (right) radiographs demonstrating interspinous wiring. Cervical stability is achieved by passing the wires through holes drilled in the spinous processes.

The Bohlman triple-wire fixation technique was a modification of the Rogers technique to stabilize a single or multilevel site of segmental instability.[22] The interspinous wiring method is similar to that of the Rogers technique in that wires are passed through drilled-out holes in the spinous processes. Additional wires are then passed through the holes and are threaded through corticocancellous iliac crest bone grafts. The two wires are tightened to secure the bone grafts against the decorticated spinous processes and laminae on each side.

When spinous processes and laminae cannot be used for fixation, facet wiring provides an additional alternative for cervical spine fusion. This method was introduced in 1977 by Callahan, et al.[9] Using this method (Fig. 3) the facet capsular ligaments are removed and the facet joints are opened. Holes are drilled at each level. A wire or cable is passed through each hole in a superior-to-inferior direction and exits through the joint space. The wires are wrapped around autologous strut grafts and fastened to decorticated articular masses. The inferior end of the bone graft is secured to the spinous process. Alternatively, Steinmann pins or Luque rectangles can replace the bone grafts to allow fixation over multiple levels as described by Garfin and associates[15] and also by Maurer, et al.[21]

Drawings demonstrating the Callahan technique of facet wiring. Holes are drilled in the facets (left) through which wires are passed and placed around the strut grafts (right). The grafts are secured to the articular masses, which have been decorticated. Reproduced with permission from the Barrow Neurological Institute.

In 1983, Cahill and colleagues[8] described an alternative technique in which the spinous process and facets are wired together (Fig. 4). This procedure is used to stabilize facet fracture dislocations or subaxial flexion–compression injuries. Usually a hole is drilled in the middle of the superior articular facet. A cable or wire is passed through the hole in the facet and looped beneath the caudal spinous process. The procedure is then repeated on the contralateral side to achieve full stabilization.

Drawing showing an alternative technique of the facet wiring described by Cahill, in which wires are placed through a hole made in the superior articular facet on each side and wrapped around the caudal spinous process. Reproduced with permission from the Barrow Neurological Institute.

The placement of sublaminar wires made of stainless steel was associated with a significant incidence of complications, including dural tears and neurological deficits. A major technical improvement in wiring techniques was the introduction of braided cables, which are flexible and stronger than stainless steel wires. In 1991 Songer, et al.,[30] introduced a cable system that consists of two 49-stranded stainless steel cables connected to one malleable leader portion. The flexibility of the cables makes it easier and safer to pass them under the laminae.

Tucker[31] first described the use of interlaminar clamps in 1975. He used Halifax interlaminar clamps (Fig. 5) for posterior C1–2 arthrodesis. Since that time, these clamps have been applied to stabilize flexion injuries at a singlemotion segment.[2] This technique requires the presence of intact laminae at the fusion level and may increase the risk of neurological injury by contributing to canal stenosis due to sublaminar hooks. Usually, bilateral interlaminar clamps are placed to optimize fixation and stability.

Drawing demonstrating the use of interlaminar clamps. The clamps are placed on each side over the laminar edges and are secured by tightening the screws. A bone graft has been placed between the spinous processes to enhance fusion. Reproduced with permission from the Barrow Neurological Institute.

Using this technique the posterior elements are exposed. The leading and trailing edges of the laminae are thinned to augment the size of the interlaminar spaces bilaterally. The clamps are hooked over the leading and trailing laminar edges. Then screws are applied and the clamps are tightened together. An autologous graft can be interposed between the two spinous processes to prevent hyperextension and enhance fusion.

In the late 1980s, Roy-Camille and colleagues[29] introduced the concept of using a lateral mass screw-and-plate system to stabilize the cervical spine. This procedure was originally the method of choice for stabilizing the cervical spine when posterior elements are compromised or absent. It provides immediate rigid stability, obviates the need for an external halo vest orthosis, and readily promotes fusion.

The original Roy-Camille procedure for managing cervical instability was modified by Magerl[19,34] Anderson,[4] and An.[3] These surgeons' techniques differ in the entrance point for screw insertion and screw trajectory. The screw is usually directed superiorly and laterally to avoid the nerve root and the vertebral artery. In the Magerl procedure, the entrance point for screw insertion is located slightly medial and rostral to the midpoint of the lateral mass. The direction of the screw is 25° lateral in the axial plane and parallel to the facet joint in the sagittal plane. In the Anderson technique, the direction of the screw is 10° lateral in the axial plane and 30 to 40° rostral in the sagittal plane. In the An technique the direction of the screw is 30° lateral in the axial plane and 15° rostral in the sagittal plane.

Lateral mass screws and rods (Fig. 6) were introduced because the lateral mass plating system cannot accommodate complex spinal abnormalities such as those occurring in severe degenerative spondylosis or trauma. In an effort to apply precise screw placement and realignment, the screw-and-rod system was developed throughout the late 1980s and the 1990s.[14,18] Currently, three systems contain this construct: the Cervifix System (Synthes), the Vertex System (Medtronic), and the Summit System (De-Puy). These systems allow for placement of the screws in the desired entry point, after which the rod is attached either by a clamp (Cervifix System) or directly onto a polyaxial head. Screw-and-rod systems can accommodate for variations in anatomy and, thereby, allow precise screw placement. They are especially useful when there is multilevel disease or a sagittal or coronal deformity, or when occipitocervical or cervicothoracic stabilization is indicated.

Lateral (left) and anteroposterior (right) radiographs demonstrating lateral mass screw-and-rod placement. The screws are first placed in the lateral masses at each level at which fusion is to be performed and then a rod is introduced to secure the construct.

In 1994, Abumi and colleagues[1] introduced and used cervical pedicle screws in a novel method of posterior cervical instrumentation. They were the first to report the successful use of these screws in stabilizing a subaxial traumatic instability, and have shown that cervical pedicle screws can be used effectively in the reconstruction of the cervical spine. The superior stability, fixation, and resistance to screw pullout provided by this technique, compared with the lateral mass plating system, has been demonstrated in animal models and in human cadavers.[20]

Once the posterior elements have been exposed, the site of the pedicle screw insertion is penetrated with a highspeed drill. The entry point has been determined to be lateral to the center of the facet and close to the posterior margin of the superior articular surface. The angle at which the screw is inserted can vary from 25 to 45° medial to the midline in the transverse plane. In the sagittal plane the angle of insertion should be parallel to the upper endplate of the vertebral body. After the entrance hole has been made, a small pedicle probe is inserted with the guidance of fluoroscopy. The appropriate pedicle is then tapped and the screw is inserted.

Given the anatomical variability in the angularity of cervical pedicles care must be taken to avoid neurovascular complications, such as vertebral artery injury, as well as nerve root injury from screw insertion.

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