Orthopedics

Feature Article 

Modified Plate-only Open-door Laminoplasty Versus Laminectomy and Fusion for the Treatment of Cervical Stenotic Myelopathy

Lili Yang, MD; Yifei Gu, MD; Jueqian Shi, MD; Rui Gao, MD; Yang Liu, MD; Jun Li, MD; Wen Yuan, MD, PhD

Abstract

The purpose of this study was to compare modified plate-only laminoplasty and laminectomy and fusion to confirm which of the 2 surgical modalities could achieve a better decompression outcome and whether a significant difference was found in postoperative 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 enlargement 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 analog 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 (yuanwen_spine@126.com).

Abstract

The purpose of this study was to compare modified plate-only laminoplasty and laminectomy and fusion to confirm which of the 2 surgical modalities could achieve a better decompression outcome and whether a significant difference was found in postoperative 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 enlargement 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 analog 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 (yuanwen_spine@126.com).

Posterior cervical decompression, including laminectomy and laminoplasty, has been widely used in the treatment of progressive myelopathy 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 laminoplasty was developed in the late 1970s in Japan as an alternative to laminectomy, with satisfactory clinical outcomes reported by many studies.1–5 Despite presumed advantages, open-door laminoplasty is not uniformly accepted compared 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 exists. Some recent studies reported good outcomes with plate-only open-door laminoplasty 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 laminoplasty 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 underwent laminectomy with instrumented fusion and modified open-door laminoplasty at the authors’ institution between November 2007 and June 2010 were retrospectively reviewed. Inclusion criteria were patients whose clinical findings were consistent with the diagnosis of progressive cervical stenotic myelopathy that failed to respond to nonsurgical treatment and patients who had cord compression at 3 or more cervical levels confirmed by radiography. Exclusion criteria were patients with severe cervical kyphosis, fracture, segmental cervical instability, tumors, metabolic disorders, and history of cervical spine surgery or combined with anterior cervical spine procedures. Twenty-two patients were lost to follow-up. A total of 141 patients (106 men and 35 women) with a mean age of 57.97±8.17 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 anterior 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 patients) and the laminectomy and fusion group (66 patients). All patients had a minimum 24-month follow-up.

Surgical Technique

The patients were placed in the prone position while under general anesthesia. A standard posterior exposure was performed for both procedures. In the laminoplasty group, the interspinous ligaments were cut at the superior and inferior ends of the target levels, with the supraspinous 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 ligaments and the total lamina with the ligamentum 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 levels. Autologous laminectomy bone was used as a bone graft.

Patient data, including age, sex, operative 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 computed tomography was obtained preoperatively to diagnose ossification of the posterior longitudinal ligament.

Six months postoperatively, osseous fusion was confirmed by computed tomography. The extent of decompression achieved was assessed by measuring 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 improvement ratio of the cross-sectional area was [(postoperative area−preoperative area)÷preoperative area]×100%. The spinal cord drift distance was assessed from the posterior margin of the posterior longitudinal ligament to the anterior margin of the spinal cord. Preoperative values were then subtracted from the postoperative values to provide the measurement of spinal cord drift (Figure 1). Pre- and postoperative cervical lordosis was measured on lateral radiographs using the cervical curvature index, as described by Ishihara.15 Range of motion (ROM) was determined using the Cobb method for C2–C7 in flexion and extension (Figure 2).

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 assessed from the posterior margin of the posterior longitudinal ligament to the anterior margin of the spinal cord (B).

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 assessed from the posterior margin of the posterior longitudinal ligament to the anterior margin of the spinal cord (B).

Lateral radiograph showing evaluation of the cervical curvature index (CCI) with the Ishihara method: CCI=(a1+a2+a3+a4)/A (A). Lateral flexion-extension radiographs showing evalutation of range of motion (ROM) as the sum of the C2–C7 Cobb angle: ROM=α+β (B, C).

Figure 2: Lateral radiograph showing evaluation of the cervical curvature index (CCI) with the Ishihara method: CCI=(a1+a2+a3+a4)/A (A). Lateral flexion-extension radiographs showing evalutation of range of motion (ROM) as the sum of the C2–C7 Cobb angle: ROM=α+β (B, C).

To evaluate the clinical outcome, the Japanese Orthopaedic Association and the Nurick scoring systems were used to assess 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, cerebrospinal fluid leakage, C5 palsy, kyphosis (kyphosis angle was measured), and axial pain (defined as a VAS score of 3 or more at 6-month follow-up) were recorded for both groups.

Results

Demographics 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) underwent laminectomy and fusion. A mean of 4.33 and 4.53 vertebral levels were operated on in the laminoplasty group and the laminectomy and fusion group, respectively. No statistical difference in sex, age, or operative levels was found between the 2 groups.

Mean operative time was 145.07±27.13 minutes in the laminoplasty group vs 173.79±29.18 minutes in the laminectomy and fusion group. Mean intraoperative blood loss was 284.53±49.52 mL in the laminoplasty group and 310.91±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).

Demographics and Surgical Parameters

Table 1: Demographics and Surgical Parameters

Clinical and Radiological Outcomes

Computed tomography scans at 6 months postoperatively showed that bone grafts were fused in 74 (98.67%) patients in the laminoplasty group and 64 (96.97%) patients in the laminectomy and fusion group. Mean cross-sectional area of the dural sac of the 3 most stenotic levels in patients was 121.51±15.20 mm2 preoperatively, 159.49±16.04 mm2 at 6 months postoperatively, and 159.17±15.81 mm2 at 24 months postoperatively in the laminoplasty group and 120.38±13.99 mm2 preoperatively, 182.07±13.20 mm2 at 6 months postoperatively, and 181.69±12.45 mm2 at 24 months postoperatively in the laminectomy and fusion group. The change rate of the 2 groups was 31.88%±11.85% in the laminoplasty group vs 52.68%±13.73% in the laminectomy and fusion group (P<.01). Mean spinal cord shift was 1.19±0.25 mm at 6 months postoperatively and 1.20±0.26 mm at 24 months postoperatively in the laminoplasty group and 2.45±0.55 mm at 6 months postoperatively and 2.44±0.56 mm at 24 months postoperatively in the laminectomy and fusion group (Table 2). The extent of spinal canal stenosis of the 2 groups was similar, 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 laminoplasty group. Decompression was well maintained 2 years postoperatively in both groups (Figures 3, 4).

Extent of Decompression Using Modified Laminoplasty and Laminectomy

Table 2: Extent of Decompression Using Modified Laminoplasty and Laminectomy

Preoperative anteroposterior (A) and lateral (B) radiographs and sagittal (C) and axial (D) magnetic 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.

Figure 3: Preoperative anteroposterior (A) and lateral (B) radiographs and sagittal (C) and axial (D) magnetic 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.

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.

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.

Mean preoperative Japanese Ortho-paedic Association scores were 8.91±1.23 and 8.65±1.05 in the laminoplasty and the laminectomy and fusion groups, respectively (P>.05). Mean postoperative Japanese Orthopaedic Association scores were 13.55±1.34 and 13.59±1.08 in the laminoplasty and the laminectomy and fusion groups, respectively (P>.05). The recovery rates were 57.29%±15.43% and 58.87%±13.36% in the laminoplasty and the laminectomy and fusion groups, respectively (P>.05). Mean preoperative Nurick scores were 2.40±0.96 and 2.52±0.93 in the laminoplasty and the laminectomy and fusion groups, respectively (P>.05). Mean postoperative Nurick scores were 0.65±0.71 and 0.68±0.68 in the laminoplasty and the laminectomy and fusion groups, respectively (P>.05). Mean preoperative NDI scores were 34.11±3.74 and 33.74±3.50 in the laminoplasty and the laminectomy and fusion groups, respectively (P>.05). Mean postoperative NDI scores were 14.67±3.04 and 16.80±4.54 in the laminoplasty and the laminectomy and fusion groups, respectively (P>.05). Mean preoperative VAS scores were 2.85±1.11 and 2.59±1.25 in the laminoplasty and the laminectomy and fusion groups, respectively (P>.05). Mean postoperative VAS scores were 1.11±1.18 and 2.15±1.38 in the laminoplasty 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 similar in both groups, and the neck function recovery was better in the laminoplasty group (Table 3).

Clinical Outcomes of Modified Laminoplasty and Laminectomy

Table 3: Clinical Outcomes of Modified Laminoplasty and Laminectomy

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

Cervical Curve Index and Range of Motion

Table 4: Cervical Curve Index and Range of Motion

Complications

No iatrogenic neurological deterioration 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, cerebrospinal fluid leakage usually stopped after 3 to 5 days of conservative treatment using 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 significantly greater change in dural sac area and a greater spinal cord shift compared with those without C5 palsy in both groups (Table 5).

Correlations Between Postoperative C5 Palsy and the Extent of Decompression

Table 5: Correlations Between Postoperative C5 Palsy and the Extent of Decompression

Axial pain lasted for more than 6 months postoperatively in 9 and 23 patients in the laminoplasty and the laminectomy and fusion groups, respectively (P<.05). Cervical lordosis was well maintained in all but 3 patients in the laminoplasty group who developed kyphosis (−2°, −5°, and −12°, respectively) and 2 patients in the laminectomy and fusion group who developed kyphosis (−4° and −11°, respectively). These patients were closely observed, and none developed serious clinical symptoms by last follow-up (Figure 5).

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

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

Restenosis, accompanied with neurological 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 operation was performed. No restenosis was observed in the laminectomy and fusion group (Table 6).

Complications

Table 6: Complications

Discussion

Many 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 decompression 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 expansion of the spinal canal with an effective spinal cord drift is achieved would directly affect the outcome of these posterior treatments.19

In previous studies, the extent of decompression by laminoplasty or laminectomy and fusion has not been compared effectively due to the lack of a measurement available. Some recent studies used the diameter or area of the spinal canal, inclination angle, and Pavlov ratio on computed 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 laminectomy and fusion because the posterior arch has been completely removed.

In the current study, the authors compared the magnitude of decompression by measuring cross-sectional area of the dural sac and posterior shift of the spinal 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 posterior drift of the spinal cord after modified 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 better recovery rate in the laminectomy and fusion group. The neurological recovery was similar in both groups.

Controversy exists over the relationship between the extent of decompression and neurological outcome. Hatta et al21 reported that the outcome of posterior decompression surgery was not correlated with the magnitude of postoperative backward shifting of the spinal cord and that increased canal diameters were associated with an increased incidence of postoperative complications, especially C5 palsy. Postoperative spinal cord drift, which may result in tethering of the nerve root, has been confirmed to cause the development 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 canal and spinal cord drift was observed in patients with C5 palsy in both the laminoplasty and the laminectomy and fusion groups. In patients with C5 palsy who underwent laminoplasty, greater inclination angles with larger-sized mini-plates were observed. Thus, strategies to reduce postoperative 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 addition, to prevent excessive decompression and spinal cord drift, the authors limited the extent of decompression during laminoplasty 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 necessary.19 However, in the current study, limited decompression with an approximate 30% increase seemed to provide enough space for the spinal cord to keep clear of compression and achieve a satisfying neurological 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 considered 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 satisfactory, and the possibility of graft dislocation 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 initial stability for the expanded spinal canal. 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 periscapular and shoulder regions postoperatively.24,25 Causes of axial symptoms have not been fully clarified. According to previous studies, axial pain may be caused by nuchal muscle injury, destruction of facet joints, intraoperative nerve root damage, or hinge-side nonunion.24–26 A high rate of postoperative axial pain has been reported with laminectomy and conventional laminoplasty.27,28 In some articles, conventional laminoplasty was associated with more postoperative axial pain, causing a poorer quality of life compared with laminectomy.29

However, in the current study, less axial pain was observed in the laminoplasty group. That is because the modified 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 cervical 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 correlated with cervical ROM.34 Laminectomy and fusion achieves intervetebral stability at the expense of losing a greater ROM, which may cause stiffness and muscle atrophy. Plate-only fixation could provide initial stability and effectively maintain ROM. In addition, immediate stability, ROM preservation, and less invasion enable patients who undergo modified laminoplasty to achieve early postoperative exercises, preventing muscle atrophy from occurring.

Posterior cervical surgery has been reported to have a high rate of postoperative 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 deformity 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 increase the risk of postoperative kyphotic deformity. However, according to recent studies, patients with servere preoperative kyphosis were not suitable for laminoplasty 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 laminoplasty. Thus, preoperative kyphosis was considered one of the relative contraindications of laminoplasty. For that reason, patients with preoperative kyphosis were excluded from the current study.

Conclusion

The results of this study demonstrated that laminectomy and fusion can achieve a greater extent of enlargement of the spinal canal and spinal cord drift compared with laminoplasty. However, a greater decompression extent did not achieve a better clinical outcome. The degree of neurological 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 laminoplasty could maintain spinal canal enlargement and lordotic alignment with a low rate of restenosis and kyphosis. Modified laminoplasty was associated with a lower rate of postopertive C5 palsy due to limited decompression. Rigid reconstruction of the spinal canal and preservation of cervical mobility combined with preservation of the bone structure and soft tissue, which is important to the stability of the posterior column, can effectively reduce postoperative axial symptoms. For this reason, modified laminoplasty may be a more viable option for patients with cervical stenotic myelopathy.

References

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Demographics and Surgical Parameters

Demographic/ParameterMean±SD
Test ValueP
Laminoplasty GroupLaminectomy and Fusion Group
Age at operation, y57.19±7.3356.98±8.34Z=−0.161.872
Age range, y42–7241–75
No. of M/F56/1949/17χ2=0.003.954
No. of operative levels4.33±0.6224.53±0.728Z=−1.769.901
Blood loss, mL284.53±49.52310.91±50.92Z=−2.985.003
Operation time, min145.07±27.13173.79±29.18Z=−5.426.000

Extent of Decompression Using Modified Laminoplasty and Laminectomy

Extent of DecompressionMean±SD
Test Value, ZP
Laminoplasty GroupLaminectomy and Fusion Group
Area of dural sac, mm2
  Preop121.51±15.20120.38±13.99−0.264.791
  Postop 6 mo159.49±16.04182.07±13.20−7.363.000
  Postop 24 mo159.17±15.81181.69±12.45−7.466.000
Increase in area, %31.88±11.8552.68±13.73−7.743.000
Spinal cord drift, mm
  Postop 6 mo1.19±0.252.45±0.55−10.185.000
  Postop 24 mo1.20±0.262.44±0.56−10.141.000

Clinical Outcomes of Modified Laminoplasty and Laminectomy

ScoreMean±SD
Test ValueP
Laminoplasty GroupLaminectomy and Fusion Group
Fusion rate, %98.6796.97χ2=0.485.486
JOA
  Preop8.91±1.238.65±1.05Z=−1.513.130
  Postop13.55±1.3413.59±1.08Z=−0.213.831
Nurick
  Preop2.40±0.962.52±0.93Z=−0.827.408
  Postop0.65±0.710.68±0.68Z=−0.324.746
NDI
  Preop34.11±3.7433.74±3.50Z=−0.342.732
  Postop14.67±3.0416.80±4.54Z=−2.556.011
VAS
  Preop2.85±1.112.59±1.25Z=−1.575.115
  Postop1.11±1.182.15±1.38Z=−4.716.000

Cervical Curve Index and Range of Motion

OutcomeMean±SD
Test Value, ZP
Laminoplasty GroupLaminectomy and Fusion Group
CCI
  Preop0.148±0.0550.146±0.050−0.531.596
  Postop0.142±0.0590.135±0.062−1.383.167
ROM, deg
  Preop29.88±6.4331.50±5.69−1.512.130
  Postop24.95±6.2411.47±5.69−9.400.000
  Loss, %15.8263.03−9.946.000

Correlations Between Postoperative C5 Palsy and the Extent of Decompression

Extent of DecompressionMean±SD
Test Value, ZP
With C5 PalsyWithout C5 Palsy
Increase in area, %
  Laminoplasty group54.28±5.3530.94±11.12−2.201.022
  Laminectomy and fusion group68.53±13.1648.90±11.38−2.757.000
Spinal cord drift, mm
  Laminoplasty group1.70±0.111.17±0.24−3.983.000
  Laminectomy and fusion group3.23±0.382.28±0.44−4.566.000

Complications

ComplicationGroup, No. (%)
Test Value, χ2P
LaminoplastyLaminectomy and Fusion
C5 radiculopathy3 (4)11 (16.67)5.216.022
CSF leakage1 (1.33)3 (4.55)1.314.252
Kyphosis3 (4)2 (3.03)0.097.756
Wound infection0 (0)1 (1.52)1.144.285
Restenosis1 (1.33)0 (0)0.574.448
Axial pain9 (12)23 (34.8)10.446.001

10.3928/01477447-20121217-23

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