modified plate-only open-door laminoplasty versus...

JANUARY 2013 | Volume 36 • Number 1

n Feature Article

abstractFull article available online at Healio.com/Orthopedics. Search: 20121217-23

Modified Plate-only Open-door Laminoplasty Versus Laminectomy and Fusion for the Treatment of Cervical Stenotic MyelopathyLiLi Yang, MD; Yifei gu, MD; Jueqian Shi, MD; Rui gao, MD; Yang Liu, MD; Jun Li, MD; Wen Yuan, MD, PhD

The purpose of this study was to compare modified plate-only laminoplasty and lami-nectomy and fusion to confirm which of the 2 surgical modalities could achieve a better decompression outcome and whether a significant difference was found in postopera-tive complications. Clinical data were retrospectively reviewed for 141 patients with cervical stenotic myelopathy who underwent plate-only laminoplasty and laminectomy and fusion between November 2007 and June 2010. The extent of decompression was assessed by measuring the cross-sectional area of the dural sac and the distance of spinal cord drift at the 3 most narrowed levels on T2-weighted magnetic resonance imaging. Clinical outcomes and complications were also recorded and compared. Significant en-largement of the dural sac area and spinal cord drift was achieved and well maintained in both groups, but the extent of decompression was greater in patients who underwent laminectomy and fusion; however, a greater decompression did not seem to produce a better clinical outcome. No significant difference was observed in Japanese Orthopaedic Association and Nurick scores between the 2 groups. Patients who underwent plate-only laminoplasty showed a better improvement in Neck Dysfunction Index and visual ana-log scale scores. In addition, limited decompression, rigid reconstruction of the spinal canal, and preservation of cervical mobility combined with preservation of the posterior structure resulted in a lower rate of postoperative C5 palsy and axial pain in the modified laminoplasty group. For this reason, modified laminoplasty may be a more viable option for patients with cervical stenotic myelopathy.

The authors are from the Department of Orthopedics (LY, YG, RG, YL, JL, WY) and the Department of Imageology (JS), Changzheng Hospital, Second Military Medical University, Shanghai, China.

Drs Yang and Gu equally contributed to this work.The authors have no relevant financial relationships to disclose.This research was supported by the Natural Science Foundation of Shanghai Science and Technology

Committee (11ZR1448400) and Innovation Program of Shanghai Municipal Education Commission (12ZZ079).

Correspondence should be addressed to: Wen Yuan, MD, PhD, Department of Orthopedics, Changzheng Hospital, Second Military Medical University, No.415 Fengyang Rd, Shanghai 200003, China ([email protected]).

doi: 10.3928/01477447-20121217-23

Figure: T2-weighted magnetic resonance image showing the extent of decompression assessed by measuring the cross-sectional area of the dural sac (arrow).

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ORTHOPEDICS | Healio.com/Orthopedics

n Feature Article

Posterior cervical decompression, including laminectomy and lami-noplasty, has been widely used in

the treatment of progressive myelopa-thy caused by stenotic conditions such as multilevel spondylosis, ossification of the posterior longitudinal ligament, and developmental spinal stenosis. Laminectomy has been a classic and standard treatment for cervical stenotic myelopathy for decades, whereas lami-noplasty was developed in the late 1970s in Japan as an alternative to laminecto-my, with satisfactory clinical outcomes reported by many studies.1-5 Despite presumed advantages, open-door lami-noplasty is not uniformly accepted com-pared with laminectomy and fusion due to several drawbacks, including reclosure problems, hinge fracture, and potential injuries to the nerve roots or the spinal cord by bone grafts at the open side.6-9

Controversy over laminoplasty still ex-ists. Some recent studies reported good outcomes with plate-only open-door lami-noplasty in patients with cervical spinal canal stenosis in which mini-plates were used to reconstruct the spinal canal.10-13 To the current authors’ knowledge, few studies compare this modified lamino-plasty with laminectomy.14 The purpose of the current study was to confirm which of the 2 surgical modalities could achieve a better decompression outcome and whether a significant difference existed in postoperative complications between the 2 techniques.

Materials and Methods Clinical data for patients who under-

went laminectomy with instrumented fusion and modified open-door lamino-plasty at the authors’ institution between November 2007 and June 2010 were retrospectively reviewed. Inclusion crite-ria were patients whose clinical findings were consistent with the diagnosis of progressive cervical stenotic myelopa-thy that failed to respond to nonsurgi-cal treatment and patients who had cord

compression at 3 or more cervical levels confirmed by radiography. Exclusion cri-teria were patients with severe cervical kyphosis, fracture, segmental cervical in-stability, tumors, metabolic disorders, and history of cervical spine surgery or com-bined with anterior cervical spine proce-dures. Twenty-two patients were lost to follow-up. A total of 141 patients (106 men and 35 women) with a mean age of 57.9768.17 years (range, 41-75 years) at surgery were included in this study. This study was approved by the Committee on Ethics of Biomedical Research.

The specific procedure was decided by the surgeons. Patients with large ante-rior osteophytes, facet degeneration, and the continuous type of ossification of the posterior longitudinal ligament typically underwent laminectomy and fusion. The 141 patients were divided into 2 groups according to procedure: the plate-only open-door laminoplasty group (75 pa-tients) and the laminectomy and fusion group (66 patients). All patients had a minimum 24-month follow-up.

surgical techniqueThe patients were placed in the prone

position while under general anesthe-

sia. A standard posterior exposure was performed for both procedures. In the laminoplasty group, the interspinous liga-ments were cut at the superior and inferior ends of the target levels, with the supra-spinous ligaments entirely preserved. At the open side, a full-thickness trough was drilled at the junction of the lateral mass and the lamina with a high-speed burr, and a partial-thickness trough was drilled at the hinge side. Because the ligamentum flavum was hypertrophic, causing double-sided compression in most patients, it was removed with part of the cortical bone at the open-side of the expanded levels. The lamina was elevated from the open side toward the hinge side for approximately 8 to 10 mm and stabilized with 8 or 10 mm mini-plates and screws. Autologous bone debris was embedded into the hinge trough as a bone graft to stimulate fusion. No bone graft was used as a strut at the open side.

In the laminectomy and fusion group, the supraspinous and interspinous liga-ments and the total lamina with the liga-mentum flavum of the target levels were removed completely with a high-speed drill and rongeur. Lateral mass screws and rods were then fixed at the decompression

Figure 1: Transverse T2-weighed magnetic resonance image showing the extent of decompression assessed by measuring the cross-sectional area of the dural sac (arrow) (A). The distance of spinal cord drift was as-sessed from the posterior margin of the posterior longitudinal ligament to the anterior margin of the spinal cord (B).

1A 1B

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CerviCal StenotiC Myelopathy | yang et al

levels. Autologous laminectomy bone was used as a bone graft.

Patient data, including age, sex, op-erative levels, intraoperative blood loss, and operative time, were recorded. Anteroposterior and lateral flexion and extension plain radiographs and magnetic resonance images were obtained pre- and postoperatively. Sagittal and coronal com-puted tomography was obtained preopera-tively to diagnose ossification of the pos-terior longitudinal ligament.

Six months postoperatively, osse-ous fusion was confirmed by computed tomography. The extent of decompres-sion achieved was assessed by measur-ing the cross-sectional area of the dural

sac at the 3 most narrowed levels on T2-weighted magnetic resonance imaging preoperatively, 6 months postoperatively, and at last follow-up. The improve-ment ratio of the cross-sectional area was [(postoperative area2preoperative area)4preoperative area]3100%. The spinal cord drift distance was assessed from the posterior margin of the poste-rior longitudinal ligament to the anterior margin of the spinal cord. Preoperative values were then subtracted from the postoperative values to provide the mea-surement of spinal cord drift (Figure 1). Pre- and postoperative cervical lordosis was measured on lateral radiographs us-ing the cervical curvature index, as de-

scribed by Ishihara.15 Range of motion (ROM) was determined using the Cobb method for C2-C7 in flexion and exten-sion (Figure 2).

To evaluate the clinical outcome, the Japanese Orthopaedic Association and the Nurick scoring systems were used to as-sess the neurological status, and the Neck Dysfunction Index (NDI) scoring system was used to assess neck function. Axial symptoms were evaluated by the 10-point visual analog scale (VAS). Complications including infection, hardware failure, ce-rebrospinal fluid leakage, C5 palsy, ky-phosis (kyphosis angle was measured), and axial pain (defined as a VAS score of 3 or more at 6-month follow-up) were re-corded for both groups.

resultsDemographics and Surgical Parameters

Seventy-five patients (56 men and 19 women) with a mean age of 57.19 years (range, 42-72 years) underwent modified plate-only laminoplasty. Sixty-six patients (49 men and 17 women) with a mean age of 56.98 years (range, 41-75 years) under-went laminectomy and fusion. A mean of 4.33 and 4.53 vertebral levels were operated on in the laminoplasty group and the lami-nectomy and fusion group, respectively. No statistical difference in sex, age, or operative levels was found between the 2 groups.

Mean operative time was 145.076 27.13 minutes in the laminoplasty group vs 173.79629.18 minutes in the laminec-tomy and fusion group. Mean intraop-erative blood loss was 284.53649.52 mL in the laminoplasty group and 310.916 50.92 mL in the laminectomy and fusion group. Patients in the laminoplasty group had less blood loss and a shorter operative time. The differences were statistically significant (Table 1).

Clinical and Radiological OutcomesComputed tomography scans at 6

months postoperatively showed that bone grafts were fused in 74 (98.67%) pa-tients in the laminoplasty group and 64

Figure 2: Lateral radiograph showing evaluation of the cervical curvature index (CCI) with the Ishihara method: CCI5(a11a21a31a4)/A (A). Lateral flexion-extension radiographs showing evalutation of range of motion (ROM) as the sum of the C2-C7 Cobb angle: ROM5a1b (B, C).

2A 2B 2C

Table 1

Demographics and Surgical Parameters

Mean6SD

Demographic/ParameterLaminoplasty

GroupLaminectomy and

Fusion Group Test Value P

Age at operation, y 57.1967.33 56.9868.34 Z520.161 .872

Age range, y 42-72 41-75

No. of M/F 56/19 49/17 x250.003 .954

No. of operative levels 4.3360.622 4.5360.728 Z521.769 .901

Blood loss, mL 284.53649.52 310.91650.92 Z522.985 .003

Operation time, min 145.07627.13 173.79629.18 Z525.426 .000

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(96.97%) patients in the laminectomy and fusion group. Mean cross-sectional area of the dural sac of the 3 most stenotic lev-els in patients was 121.51615.20 mm2 preoperatively, 159.49616.04 mm2 at 6 months postoperatively, and 159.17615.81 mm2 at 24 months post-operatively in the laminoplasty group and 120.38613.99 mm2 preoperatively, 182.07613.20 mm2 at 6 months post-operatively, and 181.69612.45 mm2 at 24 months postoperatively in the laminec-tomy and fusion group. The change rate of the 2 groups was 31.88%611.85% in the laminoplasty group vs 52.68%613.73% in the laminectomy and fusion group (P,.01). Mean spinal cord shift was 1.1960.25 mm at 6 months postopera-tively and 1.2060.26 mm at 24 months postoperatively in the laminoplasty group and 2.4560.55 mm at 6 months postop-eratively and 2.4460.56 mm at 24 months postoperatively in the laminectomy and fusion group (Table 2). The extent of spi-nal canal stenosis of the 2 groups was sim-ilar, and both groups achieved significant decompression. However, the extent of enlargement of the spinal canal and spinal cord drift in the laminectomy and fusion group was greater than that in the lami-noplasty group. Decompression was well maintained 2 years postoperatively in both groups (Figures 3, 4).

Mean preoperative Japanese Ortho-paedic Association scores were 8.9161.23 and 8.6561.05 in the lami-noplasty and the laminectomy and fu-sion groups, respectively (P..05). Mean postoperative Japanese Orthopaedic Association scores were 13.5561.34 and 13.5961.08 in the laminoplasty and the laminectomy and fusion groups, respec-tively (P..05). The recovery rates were 57.29%615.43% and 58.87%613.36% in the laminoplasty and the laminec-tomy and fusion groups, respectively (P..05). Mean preoperative Nurick scores were 2.4060.96 and 2.5260.93 in the laminoplasty and the laminectomy and fusion groups, respectively (P..05).

Mean postoperative Nurick scores were 0.6560.71 and 0.6860.68 in the lamino-

plasty and the laminectomy and fusion groups, respectively (P..05). Mean pre-

Table 2

Extent of Decompression UsingModified Laminoplasty and Laminectomy

Mean6SD

Extent of DecompressionLaminoplasty


Fusion Group Test Value, Z P

Area of dural sac, mm2

Preop 121.51615.20 120.38613.99 20.264 .791

Postop 6 mo 159.49616.04 182.07613.20 27.363 .000

Postop 24 mo 159.17615.81 181.69612.45 27.466 .000

Increase in area, % 31.88611.85 52.68613.73 27.743 .000

Spinal cord drift, mm

Postop 6 mo 1.1960.25 2.4560.55 210.185 .000

Postop 24 mo 1.2060.26 2.4460.56 210.141 .000

Abbreviations: postop, postoperative; preop, preoperative.

Figure 3: Preoperative anteroposterior (A) and lateral (B) radiographs and sagittal (C) and axial (D) mag-netic resonance images (MRIs) of a 58-year-old woman who developed numbness in both hands and weakness in her extremities for 3 years combined with unbalanced gait for 1 year showing that the spinal cord was compressed at C3-C7. Postoperative anteroposterior (E) and lateral (F) radiographs after 5-level laminoplasty with mini-plates showing that the posterior structures were well protected. Sagittal (G) and axial (H) MRIs showing a 34% increase in area of the spinal canal and a 0.9 mm drift of the spinal cord was achieved. The patient’s Japanese Orthopaedic Association score improved from 7 preoperatively to 14 postoperatively.

3A 3B 3C 3D

3E 3F 3G 3H

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operative NDI scores were 34.1163.74 and 33.7463.50 in the laminoplasty and the laminectomy and fusion groups, re-spectively (P..05). Mean postopera-tive NDI scores were 14.6763.04 and 16.8064.54 in the laminoplasty and the laminectomy and fusion groups, respec-tively (P..05). Mean preoperative VAS scores were 2.8561.11 and 2.5961.25 in the laminoplasty and the laminectomy and fusion groups, respectively (P..05). Mean postoperative VAS scores were 1.1161.18 and 2.1561.38 in the lami-noplasty and the laminectomy and fusion groups, respectively (P,.01). Although laminectomy and fusion achieved a greater extent of decompression and spinal cord shift than laminoplasty, the neurological function recovery was simi-lar in both groups, and the neck function recovery was better in the laminoplasty group (Table 3).

The cervical curvature index was maintained in both groups, and no signifi-cant difference existed in pre- and post-operative scores between the 2 groups. Preoperative ROM was similar in both groups. However, a significantly greater loss of ROM was observed in the laminec-tomy and fusion group (Table 4).

ComplicationsNo iatrogenic neurological dete-

rioration or surgery-related hardware failure was observed in any patient. Cerebrospinal fluid leakage occurred in 1 patient in the laminoplasty group and 3 patients in the laminectomy and fusion group due to tight adhesion causing dural tear intraoperatively. However, cerebro-spinal fluid leakage usually stopped after 3 to 5 days of conservative treatment us-ing local pressure.

C5 palsy occurred in 3 and 11 patients in the laminoplasty and the laminectomy and fusion groups, respectively (P,.05).The C5 palsy rate in the laminoplasty group was significantly higher than that in the laminectomy and fusion group. Patients with C5 palsy showed a signifi-

Figure 4: Preoperative anteroposterior (A) and lateral (B) radiographs and sagittal (C) and axial (D) magnetic resonance images (MRIs) of a 52-year-old man who developed numbness and weakness in his extremities for 5 years and had an unbalanced gait for 6 months showing that the spinal cord was compressed at C2-C6. Postoperative anteroposterior (E) and lateral (F) radiographs after 5-level laminectomy with screw and rod fixation showing that the posterior structures were partially destroyed. Sagittal (G) and axial (H) MRIs showing that a 42% increase in area of the spianl canal and a 2.1 mm drift of the spinal cord was achieved. The patient’s Japanese Orthopaedic Association score improved from 8 preoperatively to 13 postoperatively.

4A 4B 4C 4D

4E 4F 4G 4H

Table 3

Clinical Outcomes of Modified Laminoplasty and Laminectomy

Mean6SD

ScoreLaminoplasty


Fusion Group Test Value P

Fusion rate, % 98.67 96.97 x250.485 .486

JOA

Preop 8.9161.23 8.6561.05 Z521.513 .130

Postop 13.5561.34 13.5961.08 Z520.213 .831

Nurick

Preop 2.4060.96 2.5260.93 Z520.827 .408

Postop 0.6560.71 0.6860.68 Z520.324 .746

NDI

Preop 34.1163.74 33.7463.50 Z520.342 .732

Postop 14.6763.04 16.8064.54 Z522.556 .011

VAS

Preop 2.8561.11 2.5961.25 Z521.575 .115

Postop 1.1161.18 2.1561.38 Z524.716 .000

Abbreviations: JOA, Japanese Orthopaedic Association; NDI, Neck Disability Index; postop, postoperative; preop, preoperative; VAS, visual analog scale.

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cantly greater change in dural sac area and a greater spinal cord shift compared with those without C5 palsy in both groups (Table 5).

Axial pain lasted for more than 6 months postoperatively in 9 and 23 pa-tients in the laminoplasty and the lami-nectomy and fusion groups, respectively (P,.05). Cervical lordosis was well maintained in all but 3 patients in the lam-inoplasty group who developed kyphosis (22°, 25°, and 212°, respectively) and 2 patients in the laminectomy and fusion group who developed kyphosis (24° and 211°, respectively). These patients were closely observed, and none developed se-rious clinical symptoms by last follow-up (Figure 5).

Restenosis, accompanied with neu-rological symptoms, was observed in 1 patient in the laminoplasty group 3 years postoperatively. However, restenosis in this patient was not caused by surgery but rather was a result of natural progression of degeneration. An anterior revision op-eration was performed. No restenosis was observed in the laminectomy and fusion group (Table 6).

discussionMany orthopedic surgeons prefer a

posterior cervical approach, including laminectomy and fusion or laminoplasty, to treat cervical stenotic myelopathy. Both procedures have been proven safe and effective.1,4,5,16 The posterior cervical approach achieves the therapeutic effect by direct and indirect decompression of the spinal cord. Direct decompression is achieved by removal or elevation of the posterior compressive bone and infolding of the ligamentum flavum. Indirect de-compression of the anterior aspect of the spinal cord is achieved by posterior drift of the spinal cord.17,18 It was previously believed that whether a sufficient expan-sion of the spinal canal with an effective spinal cord drift is achieved would direct-ly affect the outcome of these posterior treatments.19

Table 4

Cervical Curve Index and Range of Motion

Mean6SD

OutcomeLaminoplasty


Fusion Group Test Value, Z P

CCI

Preop 0.14860.055 0.14660.050 20.531 .596

Postop 0.14260.059 0.13560.062 21.383 .167

ROM, deg

Preop 29.8866.43 31.5065.69 21.512 .130

Postop 24.9566.24 11.4765.69 29.400 .000

Loss, % 15.82 63.03 29.946 .000

Abbreviations: CCI, cervical curve index; postop, postoperative; preop, preoperative; ROM, range of motion.

Figure 5: Lateral radiograph of 57-year-old man with cervical stenotic myelopathy showing that the preop-erative C2-C7 cobb angle was 16°(A). Lateral radiograph 2 years postoperative showing that a 8° kyphosis developed (B). However, no neurological deterioration occurred.

5A 5B

Table 5

Correlations Between Postoperative C5 Palsy and the Extent of Decompression

Mean6SD

Extent of Decompression With C5 Palsy Without C5 Palsy Test Value, Z P

Increase in area, %

Laminoplasty group 54.2865.35 30.94611.12 22.201 .022

Laminectomy and fusion group

68.53613.16 48.90611.38 22.757 .000

Spinal cord drift, mm

Laminoplasty group 1.7060.11 1.1760.24 23.983 .000

Laminectomy and fusion group

3.2360.38 2.2860.44 24.566 .000

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In previous studies, the extent of de-compression by laminoplasty or laminec-tomy and fusion has not been compared effectively due to the lack of a measure-ment available. Some recent studies used the diameter or area of the spinal canal, in-clination angle, and Pavlov ratio on com-puted tomography scans or radiographs to assess enlargement of the spinal canal in patients who undergo laminoplasty.11,20 However, these measurements cannot be used in patients who undergo laminecto-my and fusion because the posterior arch has been completely removed.

In the current study, the authors com-pared the magnitude of decompression by measuring cross-sectional area of the dural sac and posterior shift of the spi-nal cord at the 3 most stenotic levels on magnetic resonance imaging. The result showed that the extent of enlargement of the dural sac cross-sectional area and pos-terior drift of the spinal cord after modi-fied laminoplasty was smaller than that after laminectomy and fusion. However, the greater enlargement of the spinal canal and spinal cord drift did not result in a bet-ter recovery rate in the laminectomy and fusion group. The neurological recovery was similar in both groups.

Controversy exists over the relation-ship between the extent of decompres-sion and neurological outcome. Hatta et

al21 reported that the outcome of posterior decompression surgery was not correlated with the magnitude of postoperative back-ward shifting of the spinal cord and that increased canal diameters were associated with an increased incidence of postopera-tive complications, especially C5 palsy. Postoperative spinal cord drift, which may result in tethering of the nerve root, has been confirmed to cause the develop-ment of C5 palsy and is considered a risk factor.22

In the current study, a greater increase in the cross-sectional area of the spinal ca-nal and spinal cord drift was observed in patients with C5 palsy in both the lami-noplasty and the laminectomy and fusion groups. In patients with C5 palsy who un-derwent laminoplasty, greater inclination angles with larger-sized mini-plates were observed. Thus, strategies to reduce post-operative spinal cord drift may reduce the risk of C5 palsy. The preserved posterior arches in modified laminoplasty helped prevent the spinal cord from backward shifting, reducing the C5 palsy rate. In ad-dition, to prevent excessive decompression and spinal cord drift, the authors limited the extent of decompression during lami-noplasty by limiting the inclination angle with appropriately sized mini-plates.

In previous research, to achieve an optimal canal expansion, a canal area

increase of more than 50% and a spinal cord shift of more than 3 mm was neces-sary.19 However, in the current study, lim-ited decompression with an approximate 30% increase seemed to provide enough space for the spinal cord to keep clear of compression and achieve a satisfying neu-rological recovery.

Maintaining expansion of the spinal canal is critical to successful posterior decompression. Restenosis of the spinal canal after conventional laminoplasty caused by reclosure or so-called spring back due to a lack of rigid fixation, non-union at the hinge side, or a slotting into the spinous process by a nonabsorbable suture is frequently reported and con-sidered a main complication compared with laminectomy and fusion.6,7 Although several modified types of reconstruction styles, including plate fixation combined with bone grafts and ceramic spacers, have been used, the results are not satis-factory, and the possibility of graft dis-location leading to reclosure and injury to the nerve root or spinal cord is also of concern.23 Although mini-plates used in modified laminoplasty cannot create a continuous osseous posterior arch, they provide a stronger support and better ini-tial stability for the expanded spinal ca-nal. Bone debris grafted at the hinge side promotes osseous fusion, which can help reconstruct a stable, rigid, and expansive laminar arch and prevent reclosure.

Axial symptoms, which are considered one of the most common complictions of posterior cervical surgury, are defined as pain and stiffness over nuchal periscapu-lar and shoulder regions postoperative-ly.24,25 Causes of axial symptoms have not been fully clarified. According to previ-ous studies, axial pain may be caused by nuchal muscle injury, destruction of facet joints, intraoperative nerve root dam-age, or hinge-side nonunion.24-26 A high rate of postoperative axial pain has been reported with laminectomy and conven-tional laminoplasty.27,28 In some articles, conventional laminoplasty was associated

Table 6

Complications

Group, No. (%)

Complication Laminoplasty Laminectomy and Fusion Test Value, x2 P

C5 radiculopathy 3 (4) 11 (16.67) 5.216 .022

CSF leakage 1 (1.33) 3 (4.55) 1.314 .252

Kyphosis 3 (4) 2 (3.03) 0.097 .756

Wound infection 0 (0) 1 (1.52) 1.144 .285

Restenosis 1 (1.33) 0 (0) 0.574 .448

Axial pain 9 (12) 23 (34.8) 10.446 .001

Abbreviation: CSF, cerebrospinal fluid.

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with more postoperative axial pain, caus-ing a poorer quality of life compared with laminectomy.29

However, in the current study, less axial pain was observed in the lamino-plasty group. That is because the modi-fied laminoplasty caused little damage to the posterior structure. Several studies have confirmed that preserving muscles attached to the C2 or C7 spinous process and reconstruction of semispinalis cer-vical muscle insertion at the C2 spinous process can prevent postoperative axial pain.30-33 In most patients who underwent laminectomy and fusion, the total lamina was removed, which can involve the C2 or C7 spinous process. However, in patients who underwent modified laminoplasty, the posterior structures, including the spinous process, muscles, ligaments, and facet joint, were properly preserved. The smaller inclination angle in laminoplasty may create a milder disturbance to the posterior structure.

Axial symptoms are strongly corre-lated with cervical ROM.34 Laminectomy and fusion achieves intervetebral stability at the expense of losing a greater ROM, which may cause stiffness and muscle at-rophy. Plate-only fixation could provide initial stability and effectively maintain ROM. In addition, immediate stabil-ity, ROM preservation, and less invasion enable patients who undergo modified laminoplasty to achieve early postopera-tive exercises, preventing muscle atrophy from occurring.

Posterior cervical surgery has been reported to have a high rate of postopera-tive kyphosis due to the aggressiveness of posterior tissue resection, facet injury, and multilevel surgery.35-37 However, cervical lordosis was well maintained in most patients in both groups in the current study. Instrumented fusion is believed to be an effective method for preventing postoperative kyphotic defor-mity and stopping progression in those who underwent laminectomy. The bone structure and soft tissue are preserved in

laminoplasty, which is important to the stability of the posterior column and has been reported to reduce the incidence of kyphosis. In addition, early excision may promote functional recovery in patients who undergo modified laminoplasty with rigid plate fixation.

Preoperative loss of lordosis may in-crease the risk of postoperative kyphotic deformity. However, according to recent studies, patients with servere preopera-tive kyphosis were not suitable for lami-noplasty because a sufficient spinal cord drift cannot be achieved.38 Through the preflex rods, laminectomy and fusion could moderately remodel the cervical curvature, which cannot be done by lami-noplasty. Thus, preoperative kyphosis was considered one of the relative contraindi-cations of laminoplasty. For that reason, patients with preoperative kyphosis were excluded from the current study.

conclusionThe results of this study demonstrated

that laminectomy and fusion can achieve a greater extent of enlargement of the spi-nal canal and spinal cord drift compared with laminoplasty. However, a greater de-compression extent did not achieve a bet-ter clinical outcome. The degree of neu-rological functional recovery was similar in the laminectomy and fusion and the laminoplasty groups, and neck function was worse in the laminectomy and fusion group.

Laminectomy and fusion and lamino-plasty could maintain spinal canal en-largement and lordotic alignment with a low rate of restenosis and kyphosis. Modified laminoplasty was associated with a lower rate of postopertive C5 pal-sy due to limited decompression. Rigid reconstruction of the spinal canal and preservation of cervical mobility com-bined with preservation of the bone structure and soft tissue, which is impor-tant to the stability of the posterior col-umn, can effectively reduce postopera-tive axial symptoms. For this reason,

modified laminoplasty may be a more viable option for patients with cervical stenotic myelopathy.

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