Overview
Cervical laminoplasty is a surgical treatment for cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament (PLL) that increases the area of the spinal canal while preserving the posterior elements, therefore eliminating the need for fusion. The procedure has several variations, but all involve decompression of the spinal canal by expanding, but not removing, the posterior arch, usually from C3 to C7; this allows the dural sac to drift posteriorly, away from compressing anterior structures. By preserving the laminae, the paraspinal muscle attachments are not compromised, minimizing the chance of postoperative instability.
Laminoplasty was first described in Japan by Hattori and colleagues in 1973, primarily as a treatment for ossification of the PLL. It has since been modified by many authors and has come to gain acceptance in North America as an alternative to laminectomy or multilevel anterior decompression, because it does not have some of their limitations. Laminoplasty seems to avoid some of the complications and morbidity associated with laminectomy, such as neurologic deterioration from postoperative segmental instability, sagittal malalignment, and perineural scarring. Laminoplasty is relatively simple and completely avoids the approach-related complications of anterior decompression and fusion, which can be particularly morbid if three or more levels are involved. Because fusion is not necessary, laminoplasty is a motion-sparing procedure that allows for earlier and more aggressive rehabilitation, theoretically decreasing the incidence of adjacent-segment disease. It also has a lower implant-associated cost than posterior or anterior instrumented fusion procedures.
Types of Laminoplasty
Hattori’s original description of laminoplasty involved a Z-plasty done by thinning the lamina laterally, making a Z-shaped cut between adjacent lamina, and then securing them together with suture. Because of the complexity and time required to successfully complete the procedure, this specific technique did not catch on. However, it was this concept that originated the development of laminoplasty.
Current laminoplasty techniques tend to fall into one of two categories, open-door or French door procedures. Neither procedure has been shown to be clinically superior, and each has advantages and disadvantages, surgeon preference being the main factor in determining their application.
Hirabayashi first described the open-door laminoplasty technique in 1978. In this procedure, a trough is created on one side of the lamina and a hinge on the other, allowing for lifting up of the entire lamina without removal of the posterior bony arch. Because of its simplicity and long-term results, this technique has become increasingly popular, and it will be described primarily in this chapter. Open-door laminoplasty is likely safer than the French door technique, because the burr is used more lateral to the midline, but it does risk injuring the dorsal venous plexus.
Kurokawa described the alternative French door laminoplasty or spinous process splitting technique in 1982. In this procedure, bilateral hinges are created at the lateral aspect of the lamina, and a complete midline osteotomy allows for opening of each hemilamina to enlarge the space available for the spinal cord. Advantages of this approach include a more symmetric, and possibly greater, expansion of the spinal canal. Although the procedure may involve less bleeding than the open-door procedure from the venous plexus, it does involve a riskier midline osteotomy, and additional time is required to make a second hinge ( Fig. 21-1 ).
Anatomy Review
- ▪
Relevant anatomy includes the osseous and ligamentous structures of the subaxial cervical spine ( Fig. 21-2 ).
Figure 21-2
Bony anatomy of the cervical spine.
- ▪
Careful attention should be paid to the muscular and ligamentous attachments of the C2 spinous process.
- ▪
The junction of the lamina and lateral mass should be carefully identified, because it is the landmark for creation of the troughs, and the facet capsules should be recognized and protected.
Indications and Contraindications
Indications
- ▪
Cervical spondolytic myelopathy involving three or more levels, including multiple disk lesions or congenital stenosis
- ▪
Ossification of the PLL with resultant multilevel cord compression
- ▪
Myelopathy as a result of posterior pathology, such as ligamentum flavum hypertropthy or calcification
- ▪
Spinal cord mass
Contraindications
- ▪
Cervical kyphosis: If the cervical spine is kyphotic, laminoplasty is strictly contraindicated, because the spinal cord will continue to stay draped along the compressing anterior structures, even when the posterior arch is removed or widened. Laminoplasty may in fact worsen postoperative kyphosis.
- ▪
Instability: Laminoplasty should be supplemented with arthrodesis if instability is present, or an alternative fusion procedure should be performed.
- ▪
Rheumatoid arthritis is a relative contraindication, because such patients may be a higher risk for postoperative instability.
Advantages and Disadvantages
Advantages
- ▪
Laminoplasty does not require fusion, and although range of motion is diminished, it is therefore still somewhat preserved when compared with fusion techniques; this may decrease adjacent-level degeneration.
- ▪
The spinal cord is decompressed without significantly compromising stability; this decreases the chance of postoperative kyphosis or listhesis.
- ▪
The procedure maintains a bony “roof” over the spinal cord, which prevents the formation of scar tissue directly on the dura. Therefore if revision is necessary, it is easier and safer to reexpose the cervical spine.
- ▪
Laminoplasty can be combined with posterior foraminotomy for concomitant radiculopathy, or it may be combined with posterior lateral mass fusion if more stability is necessary.
- ▪
Completely avoids all of the approach-related complications of anterior decompression, which can be particularly challenging when multiple levels are involved, and it can be accomplished more quickly than a multilevel anterior decompression, which decreases morbidity, particularly in the elderly.
Disadvantages
- ▪
Range of motion is reduced after laminoplasty, up to 30% to 50%, particularly in extension, lateral bending, and rotation.
- ▪
Axial neck pain is common after laminoplasty, and it occurs in up to 25% of patients. Some may consider preoperative neck pain a relative contraindication, and it is reasonable to consider a posterior fusion combined with laminoplasty in these patients.
Operative Technique
Equipment
- ▪
Regular operating room (OR) table with Mayfield tongs
- ▪
Headlights and surgical loupes
- ▪
Portable fluoroscopy for localization
- ▪
Retractors (cerebellar, Adson-Beckman)
- ▪
M-8 or 3-mm cutting burr with round tip
- ▪
Saw blade
- ▪
Kerrison rongeurs (1, 2, and 3 mm)
- ▪
Fresh-frozen or freeze-dried allograft, or “mini” laminoplasty plates
- ▪
Hemostatic agents (FloSeal, thrombin gel)
Positioning
- ▪
General anesthesia is performed without significant manipulation to the neck to avoid spinal cord injury in the face of myelopathy. Fiberoptic intubation is therefore preferred.
- ▪
Neuromonitoring electrodes should be placed before placing the patient prone, and baseline somatosensory evoked potentials and motor-evoked potentials can be recorded.
- ▪
Mayfield tongs are applied. The single pin is centered just above the ear, and the double pins are placed at the same level on the opposite side. The frame is tightened until the pressure indicator reads 60. The tongs are stabilized to the table after the patient is placed prone ( Fig. 21-3 ).
Figure 21-3
The patient is positioned prone with the head and neck extending over the edge of table. The head is stabilized with Mayfield tongs in a neutral position, and all bony prominences are padded. The knee is bent to prevent the patient’s sliding while the table is placed in reverse Trendelenburg position to decrease venous bleeding.
- ▪
The patient is log-rolled onto the OR table in the prone position; careful attention is given to neck stability during transfer to avoid spinal cord injury.
- ▪
Neck positioning is critical: the optimal position is slight flexion, which facilitates exposure and closure by tensioning skin folds, and it opens the interlaminar spaces ( Fig. 21-4 ). This is the opposite of a posterior fusion procedure, in which slight neck extension is recommended.
Figure 21-4
Slight cervical flexion is beneficial.
- ▪
The arms are placed at the patient’s side and are held in position with a draw sheet. The knees are flexed to prevent distal migration of the patient. Bony prominences should be well padded, and the shoulders can be taped down to improve radiographic visualization.
- ▪
The table is placed in reverse Trendelenburg position to facilitate venous drainage and decrease bleeding.
Prepping and Draping
- ▪
The bony landmarks are palpated. The spinous processes of C2 and C7 are most prominent and are easily identified ( Fig. 21-5 ).
Figure 21-5
Bony prominences are palpated beneath the skin. The occipital protuberance and C2, C7, and T1 spinous processes are easily palpated. An incision is made from the inferior occipital protuberance to the T1 spinous process.
- ▪
The neck is shaved superiorly to the level of the occipital protuberance.
- ▪
The field is prepped and draped in a sterile fashion using towels and Ioban from the external occipital protuberance to the spinous process of approximately T3.
Incision and Exposure
- ▪
Posterior longitudinal midline incision is made from C2 to C7. A long incision is necessary because of the tight ligamentum nuchae ( Fig. 21-6 ).
Figure 21-6
A midline longitudinal incision is made over the operative cervical levels. Dissection is carried down to the spinous processes, predominantly an avascular plane. Care is taken to ensure the intraspinous ligament is left intact and the posture tension band is undisturbed.
- ▪
The ligamentum nuchae is divided; care is taken to stay in the midline, because developing this natural avascular plane decreases bleeding significantly. Meticulous hemostasis with electrocautery should be maintained through the subcutaneous tissue.
- ▪
A subperiosteal dissection is carried out from C3 to C7, reflecting the paraspinal muscles laterally ( Fig. 21-7 ). Care should be taken to prevent penetration of the widened interspinous spaces. The C2 and C7 spinous processes are also exposed, and care is taken to preserve the midline posterior ligamentous complex during the dissection.
Figure 21-7
The ligamentum nuchae is incised in the midline, followed by subperiosteal dissection of the paravertebral muscles exposing the facet joints. The muscle attachments of C2 are not released.
- ▪
Laterally the dissection should extend to the middle of the lateral masses of C3 to C7 with preservation of the facet capsules. This can be facilitated with use of a lap sponge under the Cobb elevator to prevent injury to the capsules. If possible, the C7 spinous process should be preserved for muscle reattachment; the cephalad portion of C7 could be removed if stenosis is present at C6–C7.
- ▪
The muscular attachments to the C2 spinous process should be preserved to prevent instability. If they are taken down, the insertion should be repaired before closure ( Fig. 21-8 ). Wide exposure of the inferior surface of the C2 lamina can aid in visualization of the C3 lateral mass.
Figure 21-8
Alternatively, the C2 muscle attachments can be released as a sleeve, which can later be sutured back down to the C2 spinous process.
- ▪
Retraction is best facilitated by two deep cerebellar retractors.
Trough Preparation
- ▪
The spinous processes can be amputated to facilitate exposure and can provide bone graft to keep the lamina open. This also decreases tension on the soft tissues for wound closure.
- ▪
The open side of the lamina should be cut first to reduce blood loss. This side should be the one with more significant radiculopathy. Additional foraminotomy can be performed on this side as well.
- ▪
The trough is made with a nonaggressive 3-mm burr at the lamina–lateral mass junction ( Fig. 21-9 ). A side-to-side sweeping manner without downward pressure minimizes the risk of canal injury. The surgeon can be more aggressive at the inferior aspect of the lamina because of the underlying ligamentum flavum, although the tendency is to not burr enough of the superior lamina, which is in fact thicker.
Figure 21-9
The trough is made at the lamina–lateral mass junction.
- ▪
The cut can be completed with a 1-mm Kerrison rongeur on the inner cortex, once it has been sufficiently thinned by the burr ( Fig. 21-10 ). It is safest to start at the inferior aspect of C6 or C7, depending on the levels of laminoplasty, and to proceed cephalad. A small curette or Penfield #4 can be used to identify bony bridges and to carefully separate the ligamentum flavum below. The ligamentum must be released for the laminoplasty to open. Great care should be taken to avoid significant epidural bleeding at this time. Bipolar electrocautery, FloSeal, or Gelfoam can be used to achieve hemostasis.
Figure 21-10
A, With the help of a 3-mm burr, a trough is made on the opening side of the lamina-facet junction. B, The lamina is detached from the facet using a 1-mm Kerrison punch.
- ▪
The hinge side is then burred on the opposite side at the same anatomic junction of the lamina and lateral mass. The outer cortex and inner cancellous bone must be removed, leaving only the inner cortex ( Fig. 21-11 ). This can be done with incremental thinning to allow creep deformation. Bone wax can be used here for hemostasis. The flexibility of the posterior elements and hinge is then continuously tested, with pressure on the corresponding spinous processes, until it is felt to be free and pliable ( Fig. 21-12 ). If the hinge side is inadvertently fractured, laminectomy and fusion should be done instead.
Figure 21-11
A trough is made in the hinged side of the lamina at the laminofacet junction. This trough needs to be wider than the opposite side to allow the lamina to hinge.
Figure 21-12
The flexibility of the posterior elements and hinge is then continuously tested with pressure on the corresponding spinous processes until it is felt to be free and pliable.
Opening the Laminoplasty
- ▪
The interspinous ligaments at C2–C3 and C6–C7 are divided. Complete release of the ligamentum flavum at the open side of the lamina must be done. Adhesions can be gently released with a Woodson probe swept under the lamina ( Fig. 21-13 ).
Figure 21-13
Once the interspinous ligaments at C2–C3 and at C7–T1 are released, the lamina is hinged open.
- ▪
The laminoplasty is then opened with gentle pressure on the spinous processes. Proceeding from caudal to cranial, pressure with a nerve hook on the open side can help facilitate the opening ( Fig. 21-14 ).
Figure 21-14
A nerve hook can be used to facilitate opening.
Posterior Arch Reconstruction using Graft or Plating
- ▪
The laminoplasty can be held open using a variety of techniques that include autograft, allograft, sutures, or plating.
- ▪
The options for autograft include the autogenous spinous processes; those of C6 and C7 are usually the appropriate size. Tricortical iliac crest pieces can also be taken. Three 4 × 15 mm pieces cut perpendicular to the ilium work well ( Fig. 21-15 ).
Figure 21-15
Three 4 × 15 mm segments are cut out of the anterior ileal crest using a sagittal saw.
- ▪
Allograft options are abundant and include freeze-dried or fresh-frozen tricortical iliac crest and rib grafts. Fresh-frozen grafts should be thawed slowly and washed with antibiotic irrigation before use. Freeze-dried grafts should be placed in saline for 10 minutes before use for rehydration.
- ▪
Troughs should be fashioned on either side of the grafts, and one side should be slightly deeper than the other to prevent dislodgment into the canal. We prefer to place the grafts at the C3, C5, and C7 laminae; the C5 graft should be slightly larger than the others because this level is at the center of the decompression and has the greatest stress. The troughs are then wedged into place; beveling allows them to fit appropriately with minimal need for any other fixation, although it may be necessary to reshape the grafts to obtain the optimal fit ( Fig. 21-16 ).
Figure 21-16
A, The prepared grafts are wedged into place at C3, C5, and C7 laminar openings. Some degree of work is needed to fashion the grafts into appropriate sizes that allow the tension of the laminae to hold them in place. The beveled edge prevents the graft from dislodging into the canal. The lamina may be stabilized with a suture through the facet capsule ( B ) or with a bone anchor placed in the lateral mass ( C ).
- ▪
Suture can be used as an alternative. It can be passed through the facet capsule on the hinge side and tied to the spinous processes.
- ▪
Plates are becoming increasingly more popular. Specifically designed laminoplasty plates are available for this purpose ( Fig. 21-17 ). All forms of fixation rely on bony healing of the hinge side to permanently hold the laminoplasty open.
Related posts:
Craniovertebral Junction Instabilities and Surgical Fixation Techniques
Surgical Approaches to the Craniovertebral Junction in Rheumatoid Arthritis
Thoracic Microdiskectomy: Lateral and Posterolateral Approaches
Lumbar Facet Screw Fixation Techniques
Surgical Management of Scheuermann Kyphosis
Primary Malignant and Benign Tumors of the Spine
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
