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1 Review Article Cervical Laminoplasty: Indications, Surgical Considerations, and Clinical Outcomes Samuel K. Cho, MD Jun S. Kim, MD Samuel C. Overley, MD Robert K. Merrill, MD JAAOS Plus Webinar JoinDr.Cho,Dr.Kim,Dr.Overley, and Dr. Merrill for the interactive JAAOS Plus Webinar discussing Cervical Laminoplasty: Indications, Surgical Considerations, and Clinical Outcomes, on Tuesday, April 17, 2018, at 8 pm Eastern Time. The moderator will be Alpesh A. Patel, MD, the Journal s Deputy Editor for Spine topics. Sign up now at Abstract Cervical laminoplasty was initially described for the management of cervical myelopathy resulting from multilevel stenosis secondary to ossification of the posterior longitudinal ligament. The general concepts are preservation of the dorsal elements, preservation of segmental motion, and expansion of the spinal canal via laminar manipulation. No clear evidence suggests that laminoplasty is superior to either posterior laminectomy or anterior cervical diskectomy and fusion. However, laminoplasty has its own advantages, indications, and complications. Surgeons have refined the technique to decrease complication rates and improve efficacy. Recent efforts have highlighted less invasive approaches that are muscle sparing and associated with less postoperative morbidity. Although the long-term outcomes suggest that cervical laminoplasty is safe and effective, continued research on the development of novel modifications that decrease common complications, such as C5 nerve palsy, axial neck pain, and loss of lordosis, is required. From the Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, NY. Dr. Cho or an immediate family member serves as a paid consultant to DePuy Synthes, Medtronic, Stryker, and Zimmer Biomet; has received research or institutional support from Zimmer Biomet; and serves as a board member, owner, officer, or committee member of AOSpine North America, the Cervical Spine Research Society, the North American Spine Society, and the Scoliosis Research Society. None of the following authors or any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this article: Dr. Kim, Dr. Overley, and Dr. Merrill. J Am Acad Orthop Surg 2018;0:1-11 DOI: /JAAOS-D Copyright 2018 by the American Academy of Orthopaedic Surgeons. Cervical laminoplasty was first described by Oyama et al 1 in 1973 for the management of cervical myelopathy secondary to degenerative pathology, such as ossification of the posterior longitudinal ligament (OPLL). Cervical laminoplasty is a lamina-preserving, posteriorly based technique that decompresses the spinal cord via expansion of the spinal canal and preserves the dorsal elements. Preservation of the posterior stabilizing elements helps avoid complications, such as kyphosis and iatrogenic instability. Indications Current indications for laminoplasty include cervical myelopathy or myeloradiculopathy secondary to OPLL, cervical spondylosis, congenital stenosis, multilevel disk herniation, and traumatic central cord syndrome. Lordotic cervical alignment allows for maximal posterior drift of the spinal cord; however, laminoplasty is effective in patients with #10 to 15 of cervical kyphosis. We prefer to perform laminoplasty in patients with neutral to lordotic alignment and minimal axial neck pain. Spinal cord compression is confirmed via MRI or CT myelography. Clinical symptoms in patients with radiographic evidence of spinal cord compression (eg, effacement of cerebrospinal spinal fluid, compression ratio,0.4, myelomalacia) have been associated with disease progression and are an indication for surgical management. 2 Some studies recommend assessing a patient s Japanese Orthopaedic Association (JOA) score Month 2018, Vol 0, No 0 1

2 Cervical Laminoplasty: Indications, Surgical Considerations, and Clinical Outcomes for myelopathy to determine the need for surgical management. Wada et al 3 recommended surgical treatment in patients with clinical manifestation of myelopathy who had a JOA score,13 and spinal cord compression observed on imaging studies. Patients with signs of myelopathy are unlikely to respond to nonsurgical treatment. In a cohort of 120 patients with cervical myelopathy, Clarke and Robinson 4 reported that 5% had a rapid onset of symptoms followed by a long period of remission, 20% had a gradual decline in function, and 75% had a stepwise decline in function. In a study of 13 patients with cervical myelopathy who experienced a preoperative period of disability of,3 months and who underwent laminoplasty, Tanaka et al 5 reported that 12 of the patients could walk postoperatively. Therefore, early surgical treatment should be considered in patients with signs of cervical myelopathy. Figure 1 Preoperative Considerations Laminoplasty allows for direct posterior decompression in patients with myelopathy secondary to congenital cervical stenosis or hypertrophy of ligamenta flava (Figure 1). In addition, laminoplasty affords indirect anterior decompression by allowing the spinal cord to migrate dorsally, such as in patients with multiple disk herniations oropll.therefore,cervicalkyphosis is a relative contraindication. In patients with a high degree of kyphosis (typically.10 to 15 ), the spinal cord is draped over the posterior aspect of the vertebral body, leading to inadequate decompression. In general, posterior procedures are indicated in patients with cervical myelopathy whose cervical spine is in neutral to lordotic alignment. Several studies have reported poor surgical outcomes in patients with local Lateral flexion (A) and extension (B) radiographs of the cervical spine demonstrating preoperative range of motion in a 74-year-old woman with cervical spondylotic myelopathy. C, Sagittal T2-weighted MRI of the cervical spine showing multilevel stenosis from C3 to C7. Lateral flexion (D) and extension (E) radiographs of the cervical spine demonstrating postoperative range of motion after C3 laminectomy and open-door laminoplasty from C4 to C6. kyphosis and MRIs on which signal intensity change is observed. In a retrospective study of 114 patients with cervical myelopathy and no signal intensity change observed on MRI who underwent laminoplasty, Suda et al 6 reported that local kyphosis.13 was associated with the highest risk of poor recovery. They also reported a high risk of poor recovery in patients with local kyphosis.5 and MRIs on which signal intensity change was observed. The authors recommended anterior decompression or posterior correction of kyphosis as an adjunct to laminoplasty in patients with local kyphosis.13. In a recent systematic review of the literature, Tetreault et al 7 evaluated the association between MRI characteristics and the surgical outcomes of patients with cervical myelopathy. The authors found low-level evidence suggesting that a greater number of segments with high signal intensity on T2-weighted MRI, low signal intensity change on T1- weighted MRI, combined T1/T2 signal intensity, and a higher signal intensity ratio are predictors of 2 Journal of the American Academy of Orthopaedic Surgeons

3 Samuel K. Cho, MD, et al Figure 2 performed also should be considered. In a study of 22 patients with cervical myelopathy and/or OPLL who underwent laminoplasty, Kohno et al 8 reported that 11 patients with a JOA recovery rate.50% had AP canal diameter enlargement of 5 mm and a mean AP canal size of 12.8 mm postoperatively. The authors reported that 11 patients with a JOA recovery rate,50% had a substantially lower change in AP canal diameter and a lower mean AP canal diameter (10 to 11 mm) postoperatively. In patients with OPLL, cervical alignment and OPLL size are evaluated using the K-line (Figure 2). The K-line is drawn from the midpoint of the spinal canal at C2 to the midpoint of the spinal canal at C7 on a midsagittal MRI. 9 In patients with a negative K-line, the posterior extent of the OPLL exceeds the K- line because of the size of the lesion and kyphotic cervical alignment. In these patients, posterior decompression may not allow for adequate posterior shift during surgery; therefore, we prefer to perform anterior decompression surgery. We prefer laminoplasty as the first line of treatment in patients with cervical myelopathy who have neutral to lordotic alignment and a positive K-line and do not have substantial axial neck pain. If cervical alignment does not meet the criteria for laminoplasty or substantial axial neck pain is present, we perform circumferential or posterior-only decompression and instrumented fusion depending on the location of spinal cord compression and alignment goals. Types of Laminoplasty Illustrations of a cervical spine showing the positive K-line (A) and negative K-line (B) as described by Fujiyoshi et al. 9 worse outcomes. In contrast, high signal intensity grade on T2- weighted MRI, compression ratio, and spinal canal diameter are not predictive of surgical outcomes. One explanation for these findings is that a high signal intensity on T2- weighted MRI indicates a broad spectrum of histologic changes (eg, edema, demyelination, ischemia, necrosis, myelomalacia, cavitation) and a wide range of recuperative potentials, and another explanation is that multilevel signal intensity, combined T1/T2 signal intensity, and a higher signal intensity ratio indicated severe damage that may be irreversible, even after surgical decompression. The prognostic value of advanced imaging modalities, including diffusion tensor imaging, functional MRI, magnetic resonance spectroscopy, and myelin water fraction measurement, is under investigation. The extent of spinal canal expansion when indirect decompression is In 1973, Oyama et al 1 described an expansive Z-shaped laminoplasty that began with exposure of the spinous processes, laminae, and facet joints. The spinous processes were excised, and a Z-shaped osteotomy was done in the thinned laminae, extending as far laterally as possible, and was fixed open with the use of suture or wire. Although surgeons have refined the manner in which the laminar cuts are made, the general concepts of this technique continue to include preservation of the dorsal elements, preservation of segmental motion, and expansion of the spinal canal via laminar manipulation. Laminoplasty is broadly categorized as unilateral open-door laminoplasty (ODL) or bilateral French-door laminoplasty (FDL). Variations in laminar bisection, hinging, fixation, and surgical approach have resulted in myriad laminoplasty techniques. Open-door Laminoplasty ODL was first described in Hirabayashi et al 10 expanded the spinal canal by hinging the posterior arch on one side at the lamina-facet junction and performing a complete Month 2018, Vol 0, No 0 3

4 Cervical Laminoplasty: Indications, Surgical Considerations, and Clinical Outcomes osteotomy on the contralateral side with greater compression and symptoms. The laminar door is kept open with the use of stay sutures that are placed through the spinous process and the facet capsule or the paravertebral muscle on the hinge side. Door reclosure is a known complication of the ODL technique. Laminae opened via this technique are prone to gradually close with time, ultimately affecting neurologic function and outcomes. In a study of 35 patients who underwent ODL, Lee et al 11 reported that open laminar reclosure at 6 months postoperatively and a 10% decrease in AP diameter was associated with recurrent spinal cord compression, which indicated that augmented techniques were necessary to keep the laminae open. Studies have described the use of holed screws in the lateral mass for suture fixation and the use of suture anchors with no radiographic evidence of door reclosure. 12,13 Although modified suture fixation techniques substantially improved reclosure rates, surgeons began using more rigid fixation in the form of bone blocks and plates. In a prospective analysis of 50 patients who underwent ODL or ODL and rigid plate fixation, Wang et al 14 reported no substantial difference in postoperative JOA score improvement between the patients in the two groups; however, the patients in the rigid plate fixation group had less axial neck pain and fewer perioperative complications, compared with patients in the ODL-only group. French-door Laminoplasty Kurokawa et al 15 first described French-door, or double-door, laminoplasty in Two bilateral gutters are formed at the junction of the lamina and the pedicle and a burr is used to bisect the spinous process midsagittally. Each half of the lamina is opened laterally, as French doors are opened. To decrease the risk associated with advancing the burr toward the spinal cord, Tomita et al 16 described using a threadwire saw to bisect the spinous process; however, this technique presented its own challenge in ensuring safe passage of the threadwire saw through the compressed epidural space of a tight spinal canal. Additional limitations of the technique described by Kurokawa et al 15 include the morbidity associated with facet disruption and the harvesting of autologous bone graft. Multiple variations of this technique involve resecting the spinous process and repurposing it as the autologous bone graft for door fixation rather than using a miniplate and intralaminar screws. 17 Less Invasive Laminoplasty Approaches All the laminoplasty techniques previously discussed involve subperiosteal dissection, effectively detaching muscles from the posterior elements of the spine. This dissection negatively affects postoperative neck pain, decreases range of motion (ROM), and accelerates progression of kyphosis. 18 Notably, failed repair of the C2 muscular attachments, especially the semispinalis cervicis, affects postoperative cervical alignment, resulting in loss of lordosis. 19 Shiraishi 20 developed a less invasive surgical approach for laminoplasty that involves using intermuscular planes. This technique uses the interval between the tips of adjacent spinous processes, which separates attachments of the right and left interspinales, semispinalis cervicis, and multifidus. In a study of 84 patients who underwent laminoplasty using the Shiraishi technique or conventional FDL, Kotani et al 21 reported that the patients who underwent laminoplasty via the Shiraishi technique had considerably less axial neck pain, less ROM loss, less muscle volume loss, and improved quality of life at a followup of 2 years. Clinical Outcomes Laminoplasty has been reported to be safe and effective in short- and long-term follow-up studies. In a short-term study of 40 patients with cervical spondylotic myelopathy who underwent laminoplasty, Hirabayashi et al 10 reported a 66% improvement in JOA scores at a mean follow-up of 3 years. The clinical relevance of this improvement is profound because the patients had a mean JOA score of 7.8 (grade 3, which is the worst functional grade) preoperatively and a mean JOA score of 13.9 (grade 1) at a follow-up of 2 years. This degree of improvement in JOA score may correlate clinically with functional improvements in activities of daily living and lead to a better quality of life. In a long-term study of 126 patients with cervical myelopathy or OPLL who underwent laminoplasty, Kawaguchi et al 22 reported maintenance of neurologic recovery at a follow-up of.10 years. The mean preoperative JOA score was 9.1. At final follow-up, the mean JOA score was 12.8 in the patients with OPLL (with a 50% recovery rate) and 14.2 in the patients with cervical spondylotic myelopathy (with a 63% recovery rate); both groups of patients improved from grade 2 to grade 1. The authors reported a substantially greater recovery rate at 10 years for patients aged,60 years (65%) than for patients aged $60 years (49.3%), indicating that outcomes are age dependent. Similarly, in a study of 35 patients with OPLL, 25 patients with cervical spondylotic myelopathy, and 5 patients with athetoid cerebral palsy who underwent FDL, Seichi et al 23 4 Journal of the American Academy of Orthopaedic Surgeons

5 Samuel K. Cho, MD, et al Table 1 Laminoplasty Versus Anterior Cervical Diskectomy and Fusion: Japanese Orthopaedic Association Score JOA Score a Study (Design) No. of Patients LP ACDF Preop Postop Preop Postop P Value b Comments Hirai et al 25 (prospective cohort) Liu et al 24 (retrospective cohort) Seng et al 26 (prospective case series with unmatched cohorts) Fang et al 27 (prospective cohort) ,0.05 c The mean JOA score and recovery rate in the ACDF group were superior to those in the LP group. The LP group had fewer complications than the ACDF group (airway problems, meralgia, C5 palsy, pseudarthrosis). There was better maintenance of lordosis in the ACDF group compared with the LP group. There was no difference in ROM c The LP group required longer surgical time and had increased blood loss compared with the ACDF group. The JOA recovery rate was similar in the two groups. The LP group had bettermaintained ROM postop than the ACDF group. Substantially more complications occurred in the ACDF group than in the LP group (mean difference) (percentage recovery) (mean difference) (percentage recovery) NR NR There was a shorter surgical time in the LP group. There was no substantial difference in JOA scores, Medical Outcomes Study 36-Item Short Form scores, Nurick disability index, ROM, or visual analog scale neck pain at 2-year follow-up. Complications (hematoma, vocal cord paresis, numbness) were higher in the ACDF group than in the LP group. Substantial loss of cervical lordosis occurred in the LP group. The LP group had fewer complications, decreased blood loss, and decreased surgical time compared with the ACDF group. ACDF = anterior cervical diskectomy and fusion, JOA = Japanese Orthopaedic Association, LP = laminoplasty, NR = not reported, postop = postoperative, preop = preoperative, ROM = range of motion a Values are given as mean 6 SD except as noted. b The threshold for statistical significance was P, 0.05 in all studies. c Comparison of postoperative JOA scores. reported maintenance of neurologic recovery in most of the patients at a follow-up of 10 years. Laminoplasty Versus Anterior Surgery Laminoplasty has distinct advantages compared with anterior surgery (Tables 1 through 3). Laminoplasty is a motion-sparing procedure that obviates the risk of pseudarthrosis; however, patients report some loss of ROM postoperatively. Additionally, a potential postoperative loss of lordosis appears to be technique dependent. Laminoplasty allows for indirect decompression, which is generally safer than direct decompression, such as in anterior corpectomy; however, symptoms can recur if decompression is inadequate, most often proximally. This scenario may result from a surgeon s desire to preserve the C2 muscle attachments. Importantly, the surgeon can perform posterior decompression with an anticipated anterior procedure performed in the future. We prefer to perform the posterior decompression initially, which may create more space for the spinal cord, thereby making the anterior surgery safer and easier. Liu et al 24 reported no difference in the JOA recovery rates between patients who underwent anterior cervical diskectomy and fusion (ACDF) and those who underwent laminoplasty. The authors concluded that both surgical approaches are effective for the management of multilevel Month 2018, Vol 0, No 0 5

6 Cervical Laminoplasty: Indications, Surgical Considerations, and Clinical Outcomes Table 2 Laminoplasty Versus Anterior Cervical Diskectomy and Fusion: Lordosis Angle and Neck Pain Score Study Preoperative C2-C7 Angle Postoperative C2-C7 Angle LP ACDF LP ACDF P Value a Hirai et al ,0.05 Liu et al NS Fang et al ,0.05 ACDF = anterior cervical diskectomy and fusion, LP = laminoplasty, NS = not significant a The threshold for statistical significance was P, 0.05 in all studies. P values compare postoperative C2-C7 angles. Exact P values were not reported. Table 3 Laminoplasty Versus Anterior Cervical Diskectomy and Fusion: Range of Motion and Rate of Nerve Palsy Preop ROM a Postop ROM a ROM Preservation a,b Nerve Palsy Study LP ACDF LP ACDF LP ACDF ROM P Value c LP ACDF Hirai et al % 51.5% NS 6.4% 2.6% Liu et al % 6 8.1% 29% 6 13%, % Seng et al (flexion 1 extension inclinometer) (flexion 1 extension inclinometer) (mean difference) (mean difference) Fang et al % 6 10% 57% 6 8.2%, % 1.9% ACDF = anterior cervical diskectomy and fusion, LP = laminoplasty, postop = postoperative, preop = preoperative, ROM = range of motion a Values are given as mean 6 SD except as noted. b Preservation of ROM was calculated as (postoperative ROM)/(preoperative ROM) 100% by Fang et al 27 and Hirai et al 25 and as (preoperative ROM postoperative ROM)/(preoperative ROM) 100% by Liu et al. 24 c P values compare the ROM preservation. The threshold for statistical significance was P, 0.05 in all studies. Exact P values were not reported. cervical spondylotic myelopathy; however, they reported a greater decrease in cervical ROM and increased complications in the patients who underwent ACDF. Similarly, in a prospective cohort study comparing ACDF and laminoplasty, Hirai et al 25 reported no substantial difference in the JOA scores between the two groups at 1-year follow-up; however, the ACDF group had better JOA scores at a follow-up of 2, 3, and 5 years than the laminoplasty group had. A higher rate of perioperative complications, including dysphagia, dysphonia, and pseudarthrosis, was reported in the ACDF group. The incidence of C5 nerve palsy was 6.4% in the laminoplasty group and 2.6% in the ACDF group. In a prospective study of 64 patients who underwent ACDF and 52 patients who underwent laminoplasty, Seng et al 26 reported no substantial difference in the JOA scores, the Neck Disability Index scores, the visual analog scale neck pain scores, or ROM between the ACDF and laminoplasty groups at a 2-year follow-up. Similar to prior studies, the authors reported more complications in the anterior surgical group than in the laminoplasty group. 26 Fang et al 27 reported no substantial difference in the JOA scores between patients who underwent ACDF and those who underwent laminoplasty at a 3-year follow-up. Laminoplasty Versus Laminectomy With Fusion Laminectomy is effective for the management of cervical spondylotic myelopathy and OPLL. A well-known complication of laminectomy is postoperative instability resulting from the removal of static and dynamic stabilizing soft-tissue structures and facet violation. This complication was a major stimulus to the development of laminoplasty. Studies on the outcomes of patients who undergo laminoplasty versus laminectomy are disparate (Table 4). In a study of 30 patients who underwent laminoplasty and 26 patients who underwent laminectomy with instrumented fusion, Highsmith et al 28 reported equivalent improvements in the mean Nurick score, the mean modified JOA score, and Odom outcomes between the patients in the two groups; however, the patients in the laminoplasty group experienced no loss of lordosis. In a prospective trial of 16 patients who were randomized to laminoplasty or laminectomy with fusion, Manzano et al 29 reported substantial improvements in pain, 6 Journal of the American Academy of Orthopaedic Surgeons

7 Samuel K. Cho, MD, et al Table 4 Laminoplasty Versus Laminectomy Study (Design) No. of Patients Mean Follow-Up in Months JOA Score Preoperative a Postoperative a P Value b Postoperative Comments Yukawa et al 32 (randomized controlled trial) Highsmith et al 28 (retrospective cohort) Manzano et al 29 (randomized controlled trial) Lee et al 31 (metaanalysis) FDL: Laminoplasty: 11.1 Laminoplasty: 14.4 LCF: 20 LC: 10.1 LC: 13.6 ODL: Laminoplasty: Laminoplasty: LCF: 26 LCF: LCF: ODL: 9 12 Laminoplasty: Laminoplasty: LCF: 7 LCF: LCF: ODL and 6 48 Laminoplasty: Laminoplasty: FDL: LCF: 290 LCF: 9.31 LCF: NS c No substantial difference in JOA score, VAS axial neck pain score, surgical time, and blood loss between the laminoplasty and skip laminectomy groups. The C2- C7 lordosis angle and ROM were similar in both groups at all follow-up points. Mean Nurick, JOA, and Odom outcome scores were similar in both groups. The LCF group had a substantial improvement in neck pain postoperatively. The laminoplasty group had no substantial change in neck pain scores. Complications requiring surgery were twice as common in the LCF group as in the laminoplasty group (P, 0.01). NS c P = 0.07 The laminoplasty group had a substantial improvement in neck, interscapular, and arm pain; Medical Outcomes Study 36- Item Short Form scores; and Neck Disability Index scores. The laminectomy group had reduced ROM postoperatively, but this was not statistically significant. Both groups had similar JOA scores, VAS scores, and loss of lordosis. The LCF group had greater long-term preservation of lordosis, but this was not statistically significant. FDL = French-door laminoplasty, JOA = Japanese Orthopaedic Association, LC = laminectomy, LCF = laminectomy and fusion, NS = not significant, ODL = open-door laminoplasty, ROM = range of motion, VAS = visual analog scale a Values are given as mean or mean 6 SD. b The threshold for statistical significance was P, 0.05 in all studies. c Exact P value not reported. Nurick grade, Neck Disability Index scores, and Medical Outcomes Study 36-Item Short Form scores in the patients who underwent laminoplasty. The patients who underwent laminectomy did not experience substantial improvements in such outcomes. Cervical ROM between C2 and C7 was reduced by 75% in the patients in the laminectomy group and by 20% in the patients in the laminoplasty group at a follow-up of 1 year; however, the difference in ROM between the two groups was not substantial. In a retrospective cohort study of 121 patients who underwent laminoplasty or laminectomy and fusion, Woods et al 30 reported no difference in the functional outcomes between the patients in the two groups. The patients who underwent laminectomy had fewer complications, less chronic pain, and lower revision surgery rates compared with the patients who underwent laminoplasty; however, these findings were not statistically significant. This study was limited by the lack of validated outcome measures and a relatively short follow-up. In a meta-analysis of seven studies that included 302 patients who underwent laminoplasty and 290 patients who underwent laminectomy and fusion for the management of multilevel spondylotic myelopathy, Lee et al 31 reported similar improvements in JOA scores and visual analog scale neck pain scores between the patients in the two groups. In a subgroup analysis of the studies with a follow-up of.18 months, Lee et al 31 reported better lordosis preservation in the patients in the laminectomy group than in the patients in the laminoplasty group. Therefore, laminectomy and fusion is generally recommended more than laminoplasty forpatientswith.10 to 15 of C2 through C7 kyphosis. Laminoplasty is more advantageous than laminectomy because it decreases the risk of postlaminectomy membrane. Postlaminectomy membrane is scar tissue posterior to the dura. This scar tissue is thought to compress or tether the spinal cord and worsen neurologic outcomes. 33,34 However, in a meta-analysis of the laminoplasty literature, Ratliff and Cooper 35 reported that despite widespread reference to postlaminectomy membrane, no evidence suggests that postlaminectomy membrane results in clinical deterioration. Month 2018, Vol 0, No 0 7

8 Cervical Laminoplasty: Indications, Surgical Considerations, and Clinical Outcomes Laminoplasty Versus Skip Laminectomy Distinct from conventional laminectomy, skip laminectomy is performed with the aim of decreasing postoperative pain, loss of lordosis, and restriction of motion via preservation of adequate extensor musculature. Skip laminectomy involves performing a laminectomy at one level in combination with a cephalad resection at the level just below the laminectomy, leaving the spinous process of the cephalad level intact. Therefore, spinous processes and extensor musculature are left intact at alternating levels of the decompression. Yukawa et al 32 reported no substantial difference between laminoplasty and skip laminectomy in terms of axial neck pain, cervical alignment, ROM, and clinical outcomes. Complications C5 Palsy A common postoperative complication of laminoplasty is C5 nerve palsy, which is thought to be attributable to posterior migration of the spinal cord with tethering of the ventral exiting nerve root. Postoperative C5 palsy may manifest in approximately 50% of patients as pure motor-related deltoid and/or biceps brachii muscle weakness. The other 50% of patients typically report sensory deficits or intractable pain in the C5 dermatome and motor weakness. Most palsies are unilateral and occur within 1 week postoperatively. Infrequently, palsy may occur between 2 and 4 weeks postoperatively. The incidence of C5 palsy after laminoplasty is commonly reported in the literature. In a study of 384 patients with cervical myelopathy who underwent anterior interbody fusion, subtotal corpectomy, laminectomy, or laminoplasty, Yonenobu et al 36 reported a 5.5% total neurologic complication rate. In general, C5 palsy resolves within months without management; however, management with strength and ROM rehabilitation is common. In a study of 1,858 patients who underwent laminoplasty, Imagama et al 37 reported that 67% of patients with postoperative C5 palsy experienced complete resolution of symptoms with nonsurgical treatment at a mean follow-up of 4.1 months. The authors also reported that patients who did not experience full recovery of motor strength had a more severe initial deficit compared with patients who experienced complete motor recovery. Therefore, a severe initial deficit may require more aggressive management. In patients with radiculopathy, we prefer to perform unilateral or bilateral foraminotomy at all the involved levels, as described by Lehman et al. 38 Axial Neck Pain Laminoplasty has not been reported to alleviate axial neck pain affecting the periscapular and trapezius regions. The reason for this may be because of facet disruption or muscle dissection. In a study of 26 patients who underwent anterior interbody fusion and 72 patients who underwent laminoplasty, Hosono et al 18 reported that the incidence of neck pain was substantially higher in the patients who underwent laminoplasty than in the patients who underwent anterior fusion (60% and 19%, respectively). Postoperative axial neck pain occurred in 26% of the patients who underwent laminoplasty, persisting for a mean of 5.5 months postoperatively and lessening within 1 to 1.5 years postoperatively. These patients were treated with a rigid cervical collar for 2 to 3 months postoperatively. Disuse atrophy and diminished ROM secondary to prolonged immobilization may result in postoperative axial symptoms after laminoplasty. The use of a soft collar as necessary for comfort and the performance of early ROM as soon as comfort allows may decrease the incidence of axial discomfort. In a prospective study of 37 patients who underwent laminoplasty from C3 through C7, 31 who underwent laminoplasty from C3 through C6 with left-sided muscle dissection, and 23 who underwent laminoplasty from C3 through C6 with right-sided muscle dissection, Hosono et al 39 reported early axial neck pain in 49% of the patients in the C3 through C7 laminoplasty group and 15% of patients in the left- or rightsided dissection C3 through C6 laminoplasty groups. The authors concluded that C7 preservation was a more important factor with regard to axial pain than detachment of the deep extensor muscles on either side was. Preservation of the semispinalis cervicis has been reported to reduce postoperative axial symptoms. In conventional C3-C7 laminoplasty, the semispinalis cervicis often is detached from the C2 spinous process to perform laminoplasty at C3 and subsequently repaired to the C2 spinous process. An osteotomy of the C2 spinous process with the semispinalis cervicis muscle attached to the osteotomized fragments may allow for repair of the muscle attachments during closure. To preserve the semispinalis cervicis attachments and achieve adequate decompression, some surgeons have proposed C3 laminectomy with C4- C7 laminoplasty. Takeuchi et al 40 reported substantially better axial neck pain scores in patients who underwent C3 laminectomy with C4-C7 laminoplasty compared with patients who underwent conventional C3-C7 laminoplasty. In a prospective review of 34 patients 8 Journal of the American Academy of Orthopaedic Surgeons

9 Samuel K. Cho, MD, et al Figure 3 closer to the C2 spinous process after laminoplasty. 42 A, Lateral radiograph of the cervical spine demonstrating neutral alignment in a patient with cervical spondylotic myelopathy. B, Sagittal T2-weighted MRI of the spine showing multilevel stenosis from C3 to C7. C, Lateral radiograph of the spine demonstrating postlaminoplasty kyphosis. D, Lateral radiograph of the spine demonstrating restoration of cervical alignment after posterior spinal fusion with instrumentation from C2 to T2. E, Sagittal T2-weighted MRI of the spine showing correction of alignment without evidence of spinal cord compression after posterior spinal fusion from C2 to T2. who underwent C3 laminectomy with C4-C7 laminoplasty, Mesfin et al 41 reported substantial improvement in Neck Disability Index scores at 6 weeks and 1 year postoperatively. Preservation of the semispinalis cervicis may be a strong factor in decreasing axial neck pain. For a few reasons, we prefer to perform C3 laminectomy rather than laminoplasty if necessary. One reason is that C3 laminectomy does not require full exposure of the C3 lamina and lessens disruption of the extensor muscle insertion at C2. In addition, C3 laminectomy does not result in clinical detriment. Instances of a C3 lamina that has been hinged open via laminoplasty fusing to the superjacent C2 lamina, thereby decreasing ROM, have been reported. 42 Performing C3 laminectomy resolves this issue. Typically, partial laminotomy is performedatc7todecompressthe cranial portion of the spinal canal, and the muscle insertion onto the C7 spinous process is preserved to maintain the suspension bridge effect. Loss of Motion Although laminoplasty is a motionpreserving procedure, substantial loss of ROM may occur. Loss of ROM may be attributed to interlaminar bony fusion between adjacent opened lamina, disruption of posterior cervical extensors, and/or prolonged use of a postsurgical cervical collar. 42 Interlaminar bony fusion occurs in 28% to 88% of patients who undergo laminoplasty, most commonly occurring at C2- C3. 23,42 Some studies speculate that this occurrence may be attributable to the opened C3 lamina becoming Loss of Lordosis Progression of loss of lordosis to kyphosis after laminoplasty appears to be technique dependent, with poorer outcomes observed in patients with postoperative kyphosis. Suda et al 6 reported that JOA score improvement was statistically lower in patients with local kyphosis.5 than in patients without local kyphosis. Preservation of muscle attachments has been reported to be essential for maintaining sagittal cervical alignment. The posterior cervical approach requires careful exposure from C3 through C7, with care taken to dissect in the avascular plane, or the raphe, between the left and right paraspinal musculature. During exposure of the lateral masses, surgeons should avoid erring laterally, which may result in facet capsule violation and lead to accelerated spondylosis, axial neck pain, and loss of lordosis. In a study of 85 patients who underwent laminoplasty from C3 through C7, Suk et al 43 reported a 30% loss of ROM and an approximately 5 loss of lordosis. Kyphosis occurred in 10.6% of the patients after laminoplasty. The authors suggested that preoperative factors affecting kyphosis are a lordosis angle,10 and a kyphotic angle during flexion that is greater than the lordotic angle during extension. The semispinalis cervicis and capitis muscles generate considerable force and act as dynamic stabilizers of the cervical spine. In a retrospective case-control study of 72 patients who underwent laminoplasty, Takeshita et al 44 reported that loss of lordosis was dependent on preservation of C2 muscle attachments (Figure 3). The loss of C2-C7 lordosis was 8.3 when the C2 lamina was split during laminoplasty, 5.2 with a C2 dome Month 2018, Vol 0, No 0 9

10 Cervical Laminoplasty: Indications, Surgical Considerations, and Clinical Outcomes laminotomy, and 1.5 when the C2 lamina was left intact during laminectomy. In a study of the MRIs of 22 patients who underwent laminoplasty, Iizuka et al 19 reported that the degree of semispinalis cervicis violation affected postoperative cervical alignment. In a study of patients who underwent laminoplasty with elevation of the C3 lamina and repair of the C2 extensor muscle attachments and patients who underwent C3 laminectomy with complete preservation of C2 extensor attachments, Iizuka et al 45 reported that preoperative and postoperative cervical lordosis was preserved in both groups. To decrease iatrogenic damage to the erector musculature, Matsuzaki et al 46 performed dome laminoplasty in 33 patients, preserving the C2 insertional anatomy for maintenance of alignment and stability of the cervical spine. The authors described a technique in which the muscular attachments to the C2 vertebra were severed from the bone and marked with suture. Subsequently, a domeshaped groove was made on the caudal surface of the C2 lamina, and the marked muscular attachments were sutured back to the C2 spinous process. Summary Laminoplasty is effective in patients with cervical myelopathy resulting from spondylotic compression, OPLL, or developmental canal stenosis. Laminoplasty is an alternative to laminectomy with instrumented fusion. The indications and relative contraindications for laminoplasty must be considered with regard to a patient s symptoms, pathology, and sagittal alignment. During laminoplasty, surgeons should attempt to preserve the semispinalis cervicis muscular attachments because disruption of the muscle may lead to increased postoperative pain, loss of anatomic alignment, and reduced cervical motion. References Evidence-based Medicine: Levels of evidence are described in the table of contents. In this article, references 14, 24-27, 29, 33, 40, and 45 are level II studies. References 3, 21, 28, 30, 31, 36, 42, and 44 are level III studies. References 5, 6, 8, 9, 11-13, 16-19, 22, 23, 37, 41, and 46 are level IV studies. References printed in bold type are those published within the past 5 years. 1. Oyama M, Hattori S, Moriwaki N, Nitta S: A new method of cervical laminectomy [Japanese]. [Zasshi] The Central Japan Journal of Orthopaedic & Traumatic Surgery1973;16: Veidlinger OF, Colwill JC, Smyth HS, Turner D: Cervical myelopathy and its relationship to cervical stenosis. Spine (Phila Pa 1976) 1981;6(6): Wada E, Suzuki S, Kanazawa A, Matsuoka T, Miyamoto S, Yonenobu K: Subtotal corpectomy versus laminoplasty for multilevel cervical spondylotic myelopathy: A long-term follow-up study over 10 years. Spine (Phila Pa 1976) 2001;26(13): Clarke E, Robinson PK: Cervical myelopathy: A complication of cervical spondylosis. Brain 1956;79(3): Tanaka J, Seki N, Tokimura F, Doi K, Inoue S: Operative results of canalexpansive laminoplasty for cervical spondylotic myelopathy in elderly patients. Spine (Phila Pa 1976) 1999;24(22): Suda K, Abumi K, Ito M, Shono Y, Kaneda K, Fujiya M: Local kyphosis reduces surgical outcomes of expansive open-door laminoplasty for cervical spondylotic myelopathy. Spine (Phila Pa 1976) 2003;28 (12): Tetreault LA, Dettori JR, Wilson JR, et al: Systematic review of magnetic resonance imaging characteristics that affect treatment decision making and predict clinical outcome in patients with cervical spondylotic myelopathy. Spine (Phila Pa 1976) 2013;15;38(22 suppl 1):S89-S Kohno K, Kumon Y, Oka Y, Matsui S, Ohue S, Sakaki S: Evaluation of prognostic factors following expansive laminoplasty for cervical spinal stenotic myelopathy. Surg Neurol 1997;48(3): Fujiyoshi T, Yamazaki M, Kawabe J, et al: A new concept for making decisions regarding the surgical approach for cervical ossification of the posterior longitudinal ligament: The K-line. Spine (Phila Pa 1976) 2008;33(26):E990-E Hirabayashi K, Watanabe K, Wakano K, Suzuki N, Satomi K, Ishii Y: Expansive open-door laminoplasty for cervical spinal stenotic myelopathy. Spine (Phila Pa 1976) 1983;8(7): Lee DH, Park SA, Kim NH, et al: Laminar closure after classic Hirabayashi open-door laminoplasty. Spine (Phila Pa 1976) 2011; 36(25):E1634-E YangSC,NiuCC,ChenWJ,WuCH,Yu SW: Open-door laminoplasty for multilevel cervical spondylotic myelopathy: Good outcome in 12 patients using suture anchor fixation. Acta Orthop 2008;79(1): Wang JM, Roh KJ, Kim DJ, Kim DW: A new method of stabilising the elevated laminae in open-door laminoplasty using an anchor system. J Bone Joint Surg Br 1998;80(6): Wang L, Song Y, Liu L, et al: Clinical outcomes of two different types of opendoor laminoplasties for cervical compressive myelopathy: A prospective study. Neurol India 2012;60(2): Kurokawa T, Tsuyama N, Tanaka H, et al: Enlargement of spinal canal by sagittal splitting of the spinous processes [Japanese]. Bessatsu Seikeigeka 1982;2: Tomita K, Kawahara N, Toribatake Y, Heller JG: Expansive midline T-saw laminoplasty (modified spinous processsplitting) for the management of cervical myelopathy. Spine (Phila Pa 1976) 1998;23 (1): Park HG, Zhang HY, Lee SH: Box-shape cervical expansive laminoplasty: Clinical and radiological outcomes. Korean J Spine 2014;11(3): Hosono N, Yonenobu K, Ono K: Neck and shoulder pain after laminoplasty: A noticeable complication. Spine (Phila Pa 1976) 1996;21(17): Iizuka H, Shimizu T, Tateno K, et al: Extensor musculature of the cervical spine after laminoplasty: Morphologic evaluation by coronal view of the magnetic resonance image. Spine (Phila Pa 1976) 2001;26(20): Shiraishi T: A new technique for exposure of the cervical spine laminae: Technical note. J Neurosurg 2002;96(1 suppl): Kotani Y, Abumi K, Ito M, et al: Minimum 2-year outcome of cervical laminoplasty 10 Journal of the American Academy of Orthopaedic Surgeons

11 Samuel K. Cho, MD, et al with deep extensor muscle-preserving approach: Impact on cervical spine function and quality of life. Eur Spine J 2009;18(5): Kawaguchi Y, Kanamori M, Ishihara H, Ohmori K, Nakamura H, Kimura T: Minimum 10-year followup after en bloc cervical laminoplasty. Clin Orthop Relat Res 2003;411: Seichi A, Takeshita K, Ohishi I, et al: Longterm results of double-door laminoplasty for cervical stenotic myelopathy. Spine (Phila Pa 1976) 2001;26(5): Liu T, Yang HL, Xu YZ, Qi RF, Guan HQ: ACDF with the PCB cage-plate system versus laminoplasty for multilevel cervical spondylotic myelopathy. J Spinal Disord Tech 2011;24(4): Hirai T, Okawa A, Arai Y, et al: Middleterm results of a prospective comparative study of anterior decompression with fusion and posterior decompression with laminoplasty for the treatment of cervical spondylotic myelopathy. Spine (Phila Pa 1976) 2011;36(23): Seng C, Tow BP, Siddiqui MA, et al: Surgically treated cervical myelopathy: A functional outcome comparison study between multilevel anterior cervical decompression fusion with instrumentation and posterior laminoplasty. Spine J 2013;13(7): Fang Z, Tian R, Sun TW, Yadav SK, Hu W, Xie SQ: Expansion open-door laminoplasty with foraminotomy versus anterior cervical discectomy and fusion for coexisting multilevel cervical myelopathy and unilateral radiculopathy. Clin Spine Surg 2016;29(1):E21-E Highsmith JM, Dhall SS, Haid RW Jr, Rodts GE Jr, Mummaneni PV: Treatment of cervical stenotic myelopathy: A cost and outcome comparison of laminoplasty versus laminectomy and lateral mass fusion. J Neurosurg Spine 2011;14(5): Manzano GR, Casella G, Wang MY, Vanni S, Levi AD: A prospective, randomized trial comparing expansile cervical laminoplasty and cervical laminectomy and fusion for multilevel cervical myelopathy. Neurosurgery 2012;70(2): Woods BI, Hohl J, Lee J, Donaldson W III, Kang J: Laminoplasty versus laminectomy and fusion for multilevel cervical spondylotic myelopathy. Clin Orthop Relat Res 2011;469(3): Lee CH, Lee J, Kang JD, et al: Laminoplasty versus laminectomy and fusion for multilevel cervical myelopathy: A metaanalysis of clinical and radiological outcomes. J Neurosurg Spine 2015;22(6): Yukawa Y, Kato F, Ito K, et al: Laminoplasty and skip laminectomy for cervical compressive myelopathy: Range of motion, postoperative neck pain, and surgical outcomes in a randomized prospective study. Spine (Phila Pa 1976) 2007;32(18): Ross JS, Robertson JT, Frederickson RC, et al; ADCON-L European Study Group: Association between peridural scar and recurrent radicular pain after lumbar discectomy: Magnetic resonance evaluation. Neurosurgery 1996;38(4): LaRocca H, Macnab I: The laminectomy membrane: Studies in its evolution, characteristics, effects and prophylaxis in dogs. J Bone Joint Surg Br 1974;56(3): Ratliff JK, Cooper PR: Cervical laminoplasty: A critical review. J Neurosurg 2003;98(3 suppl): Yonenobu K, Hosono N, Iwasaki M, Asano M, Ono K: Neurologic complications of surgery for cervical compression myelopathy. Spine (Phila Pa 1976) 1991;16(11): Imagama S, Matsuyama Y, Yukawa Y, et al; Nagoya Spine Group: C5 palsy after cervical laminoplasty: A multicentre study. J Bone Joint Surg Br 2010;92(3): Lehman RA Jr, Taylor BA, Rhee JM, Riew KD: Cervical laminaplasty. J Am Acad Orthop Surg 2008;16(1): Hosono N, Sakaura H, Mukai Y, Yoshikawa H: The source of axial pain after cervical laminoplasty-c7 is more crucial than deep extensor muscles. Spine (Phila Pa 1976) 2007;32(26): Takeuchi K, Yokoyama T, Aburakawa S, et al: Axial symptoms after cervical laminoplasty with C3 laminectomy compared with conventional C3-C7 laminoplasty: A modified laminoplasty preserving the semispinalis cervicis inserted into axis. Spine (Phila Pa 1976) 2005;30 (22): Mesfin A, Park MS, Piyaskulkaew C, et al: Neck pain following laminoplasty. Global Spine J 2015;5(1): Iizuka H, Iizuka Y, Nakagawa Y, et al: Interlaminar bony fusion after cervical laminoplasty: Its characteristics and relationship with clinical results. Spine (Phila Pa 1976) 2006;31(6): Suk KS, Kim KT, Lee JH, Lee SH, Lim YJ, Kim JS: Sagittal alignment of the cervical spine after the laminoplasty. Spine (Phila Pa 1976) 2007;32(23):E656-E Takeshita K, Seichi A, Akune T, Kawamura N, Kawaguchi H, Nakamura K: Can laminoplasty maintain the cervical alignment even when the C2 lamina is contained? Spine (Phila Pa 1976) 2005;30 (11): Iizuka H, Nakajima T, Iizuka Y, et al: Cervical malalignment after laminoplasty: Relationship to deep extensor musculature of the cervical spine and neurological outcome. J Neurosurg Spine 2007;7(6): Matsuzaki H, Hoshino M, Kiuchi T, Toriyama S: Dome-like expansive laminoplasty for the second cervical vertebra. Spine (Phila Pa 1976) 1989;14 (11): Month 2018, Vol 0, No 0 11