Cervical Laminoplasty Michael P

The Spine Journal 6 (2006) 274S–281S Cervical laminoplasty Michael P. Steinmetz, MD, Daniel K. Resnick, MD* Department of Neurosurgery, University of Wisconsin School of Medicine, K4/834 Clinical Science Center, 600 Highland Ave., Madison, WI 53792, USA Abstract Laminoplasty was developed to treat multilevel pathology of the cervical spine, namely ossification of the posterior longitudinal ligament and cervical spondylotic myelopathy. Laminoplasty was pop- ularized in the 1980s, and since then many variations on the theme have been developed. All are similar in that they expand the cervical canal while leaving the protective dorsal elements in place. Advocates claim that this prevents the formation of the ‘‘postlaminectomy’’ membrane, maintains spinal alignment, and should aid in maintaining cervical range of motion. The aforementioned are all potential shortcomings of laminectomy or laminectomy and fusion. The procedure has proven to be essentially equal to other cervical decompressive procedures in the neutral or lordotic spine, and outcome has been shown to be durable. Ó 2006 Elsevier Inc. All rights reserved. Keywords: Laminoplasty; Cervical spine; Laminectomy; Ossification of the posterior longitudinal ligament; Cervical spondylotic myelopathy; Myelopathy; Cervical stenosis Introduction potentially reduce the incidence of postoperative instability. Cervical motion is theoretically preserved. In 1973, Oyama Cervical laminectomy has long been the treatment for et al. introduced a Z-plasty of the cervical spine [1]. This multilevel cervical spondylosis. It permits adequate decom- procedure allowed decompression, while the retained lam- pression of the cervical spinal cord and is safe and easily inae provided support and prevented invasion of the postla- performed. Potential adverse outcomes after cervical lami- minectomy membrane. Hirabayashi et al. reported on the nectomy include instability and epidural scar formation. It open-door laminoplasty in 1981 [2]. Following this publi- has been hypothesized that this scar may be responsible cation, various modifications have been developed that for persistent postoperative cervical and head pain after sur- are purported to improve the safety and effectiveness of gery and even neurologic deterioration. Fear of instability the procedure. has resulted in many surgeons performing a simultaneous fusion operation at the time of laminectomy. This potentially adds morbidity to the procedure, there may be non- union or construct failure, and it reduces motion in the Goals of laminoplasty cervical spine. Laminoplasty was developed to widen the spinal canal The main goal of laminoplasty is to provide decompres- dimensions without permanently removing the dorsal ele- sion of the spinal cord by widening the spinal canal while ments of the cervical spine. The retained dorsal elements preventing instability after decompression (ie, development should aid in the prevention of muscle scarring to the dura of kyphosis) and scar in-growth with potential neurological (ie, result in less cervical and head pain after surgery) and deterioration after surgery. The development of postsurgical cervical kyphosis is well described [3–5], especially in chil- FDA device/drug status: approved but not for this indication (mini- dren [6]. The risk has been shown to be reduced with lateral plates). mass fixation [7], and theoretically with laminoplasty, al- Author DKR acknowledges a financial relationship (consultant with though some loss of lordosis is often seen. Medtronic) that may indirectly relate to the subject of this research. The maximum region of canal expansion is on the open * Corresponding author. Dept. of Neurological Surgery, University of Wisconsin School of Medicine, K4/834 Clinical Science Center, 600 High- side in hinge-type procedures and in the midline in bilateral land Ave., Madison, WI 53792. Tel.: (608) 263-9651; fax: (608) 263-1728. hinge operations. Migration of the cord away from the ven- E-mail address: [email protected] (D.K. Resnick) tral vertebral bodies has been documented in both varieties 1529-9430/06/$ – see front matter Ó 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.spinee.2006.04.023 M.P. Steinmetz and D.K. Resnick / The Spine Journal 6 (2006) 274S–281S 275S of laminoplasties [8,9]. This has been confirmed with postoperative computed tomographic myelography. Although the performance of a laminoplasty procedure allows for a decompression without a fusion, there still does appear to be some loss of motion associated with the procedure. Many studies have reported a loss in cervical range of motion (ROM) after laminoplasty. The degree of loss of ROM ranges from 17% to 50% in published series, with most authors reporting an approximate 50% loss of global ROM [2,10–25]. The loss of ROM is in flexion, extension, rotation, and lateral bending. It is of note that some authors have not reported any change of ROM after laminoplasty [26]. The loss of ROM after laminoplasty should be taken in context, however, as fusion results in a much more sub- stantial loss of motion [27,28]. Some authors believe that the increased stiffness seen after laminoplasty decreases the potential for injury to the cord via dynamic movements [29] and aids in the resolution of ossification of the posterior longitudinal ligament (OPLL) [25]. In contrast, some authors believe that maintaining ROM is crucial. For example, Shaffrey et al. empha- sized the maintenance of cervical ROM via laminoplasty as a means to avoid adjacent-segment disease [30]. Fig. 1. In the Z-Plasty, troughs are first drilled into the lamina at the junction of the lateral mass. The laminae are then thinned. After this, a ‘‘Z’’ is Limitations and contraindications cut in the laminae with a high-speed drill. Note the dotted line of the proposed cut. Indications for laminoplasty include multilevel cervical spondylosis and OPLL. It may also be used for certain varieties of spinal cord tumors. The procedure is generally Z-Plasty contraindicated in kyphotic cervical pathology. It is possi- This technique was originally described by Oyama et al. ble to perform laminoplasty in a straightened spine, but [1]. In this procedure, the spinous processes are first re- a lordotic posture is preferred. As noted above, most studies moved and the laminae thinned. They are thinned out to document loss of cervical lordosis after surgery. Lamino- the laminae–facet junction. Troughs are performed later- plasty is generally not indicated for one- or two-level dis- ally. At this point a ‘‘Z’’ is cut into the thinned laminae ease. The limited length of decompression in such cases (Fig. 1). This may be performed with a high-speed drill generally does not allow the free migration of the spinal and diamond drill bit or a fine Kerrison punch. After the cord away from the ventral elements. ‘‘Z’’ cut, the thinned sections of laminae may then be sep- arated and the canal opened or expanded. The laminae may then be secured with suture or wire to maintain the expanded canal (Fig. 2). Laminoplasty techniques Many techniques that are variations of laminoplasty Hirabayashi laminoplasty have been described. They are all similar in that they expand the cervical canal and preserve some or all of the Hirabayashi and colleagues described the expansive posterior elements. Modifications on where the cuts in open-door laminoplasty [2]. In this technique, the spinous the lamina or spinous processes are made and how the ca- processes and laminae are exposed from C2–C7. The supra- nal is kept open have been developed. Newer techniques, spinous and interspinous ligaments are preserved and not such as the use of ceramic spacers and titanium mini- injured. In the authors’ experience, the ligaments must be plates have been proposed, which may decrease the surgi- cut between C2 and C3 and C7 and T1, depending on cal time and improve the safety of the procedure. No one which levels are to be expanded. This aids in ‘‘opening procedure has proven to be more effective than any other the door’’. Using a high-speed drill, a trough is created in terms of neurological outcome, cervical alignment, or on the ‘‘open’’ side at the junction between the laminae ROM. and the facets (Fig. 3). The trough is drilled down to the 276S M.P. Steinmetz and D.K. Resnick / The Spine Journal 6 (2006) 274S–281S Fig. 4. After drilling the complete trough on the open-door side, a second trough is drilled on the closed side. Care must be taken not to drill all the way through the lamina. This will lead to fracture of the hinge and an in- effective open-door laminoplasty. expand the opening with a Penfield dissector or curette Fig. 2. After the cuts, the laminae are spread apart and held with wires or while an assistant gently rotates the laminae towards the suture, effectively widening the canal. closed side using a Kocher or similar instrument (Fig. 5). Care must be taken to not allow the block of laminae to slip and rapidly snap back into original position; this may result ligamentum flavum. One may drill all the way through the in a spinal cord injury. The door may be kept open by plac- laminae or one may leave a very thin remnant of laminae, ing suture through the facet capsule on the closed side and especially at its cranial aspect. This thin rim and associated through the spinous processes (Fig. 6). Many variations on ligament are then removed with a 1-mm or 2-mm Kerrison punch. A second trough is then drilled in the opposite or ‘‘closed’’ side with a high-speed drill (Fig. 4). Care is taken to only thin the lamina on this side and not cut all the way through. This trough is cut somewhat more lateral as com- pared with the ‘‘open’’ side. The opening on the open side is then gently expanded, thus lifting the lamina off the spinal cord and expanding the canal.

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