Prediction of spinal canal expansion following cervical laminoplasty: a computer-simulated comparison between single and double-door techniques

A Three-Dimensional Morphological Assessment for Evaluating Pre- and Postsurgery in Cervical Laminoplasty

OBJECTIVE

The efficacy of medical treatments and the changes in radiologic imaging before and after treatment have consistently remained pivotal factors. This is particularly critical for surgical procedures, where precise evaluation of disparities pre and postsurgery or the accuracy of implantation is paramount. Based on three-dimensional morphological interests, we provide an automatic quantification evaluation method that delivers an evident base for assessing the outcomes of a widely employed surgical technique, cervical laminoplasty.

METHODS

The sample study included patients who underwent cervical laminoplasty for cervical spondylotic myelopathy/ossification of the longitudinal ligament. We present a superimposition method that facilitates a unique and precise assessment between pre and postsurgery. The degree of expansion was evaluated by the canal volume increase and canal expansion rate after surgery.

RESULTS

There were 31 patients with 112 vertebral segments measured. The target cervical's pre and postoperative canal areas were 122.63 ± 30.34 and 196.50 ± 37.10 mm2, respectively (P < 0.001). The average cervical canal expansion rate was 64.42%. The expansion effect of C5 cervical laminoplasty was the maximum (71.01%), and the canal volume of other segments expanded by approximately 60%. The functional outcomes demonstrated significant improvements in symptoms.

CONCLUSIONS

The quantification evaluation method can be utilized for any morphology changes before and after laminoplasty, as it does not lead to errors or variations from different inspection machines or human factors. The automatic method delivers an evident base for assessing the outcomes of a widely employed surgical technique.

An innovative approach to assess spinal canal expansion following French-door cervical laminoplasty by intraoperative ultrasonography

OBJECTIVE

To investigate the feasibility and effectiveness of applying intraoperative ultrasound (IOUS) to evaluate spinal canal expansion in patients undergoing French-door cervical laminoplasty (FDCL).

MATERIALS AND METHODS

Twenty-five patients who underwent FDCL for multilevel degenerative cervical myelopathy were prospectively recruited. Formulae describing the relationship between laminoplasty opening angle (LOA) and laminoplasty opening size, the increase in sagittal canal diameter and the spinal canal area were deduced with trigonometric functions. The LOA was measured with IOUS imaging during surgery, and other spinal canal parameters were assessed. Actual spinal canal enlargement was verified on postoperative CT images. Linear correlation analysis and Bland‒Altman analysis were used to evaluate correlation and agreement between the intraoperative and postoperative measurements.

RESULTS

The LOA at C5 measured with IOUS was 27.54 ± 3.12°, and it was 27.23 ± 3.02° on postoperative CT imaging. Linear correlation analysis revealed a significant correlation between IOUS and postoperative CT measurements (r = 0.88; p < 0.01). Bland-Altman plots showed good agreement between these two methods, with a mean difference of 0.30°. For other spinal canal expansion parameter measurements, correlation analysis showed a moderate to a high degree of correlation (p < 0.01), and Bland-Altman analysis indicated good agreement.

CONCLUSION

In conclusion, during the French-door cervical laminoplasty procedure, application of IOUS can accurately evaluate spinal canal expansion. This innovative method may be helpful in improving surgical accuracy by enabling the operator to measure and determine canal enlargement during surgery, leading to ideal clinical outcomes and fewer postoperative complications.

CLINICAL RELEVANCE STATEMENT

The use of intraoperative ultrasonography to assess spinal canal expansion following French-door cervical laminoplasty may improve outcomes for patients undergoing this procedure by providing more accurate measurements of spinal canal expansion.

KEY POINTS

• Spinal canal expansion after French-door cervical laminoplasty substantially influences operative prognosis; insufficient or excessive lamina opening may result in unexpected outcomes. • Prediction of spinal canal expansion during surgery was previously impracticable, but based on this study, intraoperative ultrasonography offers an innovative approach and strongly agrees with postoperative CT measurement. • Since this is the first research to offer real-time canal expansion guidance for cervical laminoplasty, it may improve the accuracy of the operation and produce ideal clinical outcomes with fewer postoperative complications.

Comparison of Clinical Outcomes of Cervical Laminoplasty for Cervical Spondylotic Myelopathy: Double-Door With Lamina Staple, Single-Door With Miniplate, and Double-Door With Spacer-A 2-Year Follow-Up Study

BACKGROUND

There were few studies to compare the outcomes of different types of cervical laminoplasties.

OBJECTIVE

To compare the clinical outcomes of double-door cervical laminoplasty with lamina staple (double-door staple), single-door cervical laminoplasty with miniplate (single-door miniplate), and double-door cervical laminoplasty with spacer (double-door spacer).

METHODS

The study involved 166 patients with cervical spondylotic myelopathy (CSM). Fifty-two patients underwent double-door staple, 63 patients underwent single-door miniplate, and 51 patients underwent double-door spacer. The clinical outcomes were measured.

RESULTS

There was no significant difference in Japanese Orthopedic Association score among the 3 groups ( P > .05). The operation time was significantly shorter in double-door staple and single-door miniplate groups than in the double-door spacer group ( P < .005). The estimated blood loss was significantly more in the single-door miniplate group than in double-door staple and double-door spacer groups ( P < .005). The expansion ratio of cervical intraspinal cross-sectional area decreased in the order of double-door staple > double-door spacer > single-door miniplate. There were no significant differences in the expansion ratio of dural sac cross-sectional area among the 3 groups.

CONCLUSION

Double-door staple, double-door spacer, and single-door miniplate can achieve favorable clinical outcomes for CSM. The blood loss of double-door staple is less than that of single-door miniplate, and the operation time of double-door staple is shorter than that of double-door spacer. The mean expansion ratio of cervical intraspinal cross-sectional area decreased in the order of double-door staple > double-door spacer > single-door miniplate. Overall, double-door staple is a safe and innovative alternative choice for treatment of CSM.

Are clinical outcomes affected by laminoplasty method and K-line in patients with cervical ossification of posterior longitudinal ligament? A multicenter study

BACKGROUND

Open-door laminoplasty (ODL) and French-door laminoplasty (FDL) are the main laminoplasty techniques used to treat cervical ossification of the posterior longitudinal ligament (C-OPLL). However, few studies have compared the outcomes of ODL and modified FDL (mFDL) for C-OPLL. We explored the differences in outcomes between ODL and mFDL for C-OPLL and analyzed the technical efficacy of each procedure in patients with K-line (+) or (-) C-OPLL.

METHODS

From January 2010 to December 2015, 202 patients with K-line (+) or (-) C-OPLL were retrospectively recruited from 4 institutions. Clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) score, JOA score recovery rate, operative time, blood loss, and complications. Univariate analysis and binary logistic regression models were adjusted for confounding factors.

RESULTS

Two hundred patients (mFDL, n = 69; ODL, n = 131) with a median follow-up of 42 months (range 36-54 months) were included. The postoperative JOA score significantly improved in both groups (P < 0.05). After adjusting for confounding factors, there was a statistically significant difference in blood loss (≥ 300 mL) between the two groups (P = 0.005), but there was no significant difference in the postoperative JOA score (≥ 14) (P = 0.062), JOA score recovery rate (≥ 0.82) (P = 0.187), or operative time (≥ 90 min) (P = 0.925). C5 palsy tended to occur more often in the mFDL group, although the difference was not significant (P > 0.05). The stratified analysis of the K-line status showed more blood loss in K-line (+) patients who underwent mFDL, but there was no significant difference in the postoperative JOA score, JOA score recovery rate, or operative time between the ODL and mFDL groups. Additionally, there was no significant difference in blood loss, postoperative JOA score, JOA score recovery rate, or operative time among all patients with K-line (+) or (-) C-OPLL in both groups.

CONCLUSIONS

Both ODL and mFDL are effective for patients with C-OPLL. However, more blood loss tends to occur during mFDL. This study showed no significant difference in the operative time or incidence of complications between the two techniques. The efficacy of ODL and mFDL was not affected by the K-line status (+ or -) in patients with C-OPLL.

A Novel Method of Making Hinges Using a Newly Designed Sharp Rongeur to Enhance Radiological and Clinical Outcomes in French-Door Cervical Expansive Laminoplasty

OBJECTIVE

Although the lamina open angle of making hinges is closely related to the outcomes of French-door laminoplasty (FDL) for treatment of cervical spondylosis, there have been no methods to predict the lamina open angle preoperatively as yet. The aim of this study was to investigate the accuracy of predicting the laminal open angle using our newly designed sharp rongeur, and to compare the postoperative outcomes and complications between the methods of making hinges using the newly designed sharp rongeur and the traditional high-speed micro-drill during the FDL.

METHODS

This was a single-center retrospective study. Following the approval of the institutional ethics committee, a total of 39 patients (Male: 28; Female: 11) diagnosed with cervical spondylos who underwent FDL in our institution between January 2018 and May 2019 were enrolled. Patients were divided into two groups based on the method of making hinges (sharp rongeur: 22 cases; high-speed micro-drill: 17 cases). The average age at surgery was 59.1 years (range: 16-85 years). The radiological parameters, clinical outcomes, modified Japanese Orthopaedic Association (mJOA) scale score, and the recovery rate of mJOA were recorded and compared between the groups, respectively. The radiological parameters and clinical measurements at pre- and post-operation stages were compared using the paired-sample t-test, the Wilcoxon signed-rank test, and the Friedman's test, and variables in the two groups were analyzed using an unpaired Student's t-test or a Mann-Whitney U test.

RESULTS

The average follow-up period was 20.4 months (range: 14.0-25.9 months), the postoperative open angle was 60.13° ± 3.69° in the rongeur group with 22.78° ± 4.34° of angular enlargement, which was significantly lower than that of 68.96° ± 1.00° in the micro-drill group with 32.75° ± 4.22° of angular enlargement (U = 19.000, p < 0.001). The rongeur group showed a higher fusion rate (34.1% vs 14.7%, χ²  = 11.340, p = 0.001), and a lower fracture rate of the lamina (7.8% vs 25.5%, χ²  = 14.185, p < 0.001) at 1-month post-surgery, compared to the micro-drill group. There were no significant differences in the clinical outcomes and postoperative complications between the two groups (p > 0.05), except in the recovery rate of mJOA scores (0.836 ± 0.138 vs 0.724 ± 0.180, U = 115.000, p = 0.042) and neck disability index (NDI) at the final follow-up (7.55 ± 10.65 vs 14.71 ± 8.72, U = 94.000, p = 0.008).

CONCLUSIONS

The special sharp rongeur with a tip angle of 20° could be a preferred method to make hinges during FDL, which can predict the laminal open angle accurately and enlarge it to about 23°, thus reducing the fracture rate and accelerating the bony fusion of hinges compared with the outcomes of the traditional micro-drill method.

Clinical and Radiological Outcomes of Two Modified Open-door Laminoplasties Based on a Novel Paraspinal Approach for Treatment of Multilevel Cervical Spondylotic Myelopathy

STUDY DESIGN

A case-control study.

OBJECTIVES

The aim of this study was to evaluate the outcomes of two modified laminoplasties (LPs) based on a novel paraspinal approach for treating multilevel cervical spondylotic myelopathy.

SUMMARY OF BACKGROUND DATA

No laminoplasty through a natural intermuscular plane mimicking Wiltse approach to minimize intraoperative injury to extensor muscles has ever been developed and studied.

METHODS

Ninety-two patients were enrolled, including patients treated with either modified LP and patients treated with concurrent conventional LP. Operation time, blood loss, and complications were recorded. Clinical outcomes were evaluated by VAS, JOA scores, and recovery rate. Cervical sagittal alignment was measured on cervical radiographs. Spinal canal expansion was assessed on CT scans. Cross-sectional area (CSA) and atrophy rate (AR) of cervical deep extensors were evaluated on MRI.

RESULTS

The average follow-up duration was 33.05, 31.55, 33.02, and 32.52 months, respectively in each group. Compared to concurrent conventional procedure, unilateral muscle-preserving procedure displayed similar, whereas bilateral muscle-preserving procedure showed significantly increased operation time and blood loss; each modified procedure resulted in comparable and satisfied perioperative clinical scores, spinal canal expansion while achieving significantly lower axial pain incidence, better cervical lordosis maintenance, and better deep extensor preservation. AR of deep extensors on the open side was significantly lower than that on the hinge side. Bilateral paraspinal approach demonstrated significantly better muscle-preservation on the open side and increased operation duration, with similar clinical scores, axial pain incidence, cervical lordosis maintenance, and spinal canal expansion compared to unilateral paraspinal approach. Loss of cervical lordosis was strongly correlated with AR of deep extensors.

CONCLUSION

Paraspinal approach is a good manner to protect deep extensor muscles; the two modified LPs have similar effects on clinical outcomes.Level of Evidence: 3.

Surgical Treatment of Multilevel Degenerative Cervical Myelopathy: Open-Door Laminoplasty and Fixation via Unilateral Approach. A Feasibility Study

Objective  We compared open-door laminoplasty via a unilateral approach and additional unilateral lateral mass screw fixation (uLP) with laminectomy and bilateral lateral mass screw fixation (LC) in the surgical treatment of multilevel degenerative cervical myelopathy (mDCM).

Methods  A retrospective cohort analysis of 46 prospectively enrolled patients (23 uLP and 23 LC). The minimum follow-up was 1 year. Neck and arm pains were evaluated with visual analog scales and disability with the Neck Disability Index (NDI). Myelopathy was rated with the modified Japanese Orthopaedic Association (mJOA) score. Cervical sagittal parameters were measured on plain and functional X-ray films with a specific software. The statistical significance was set at p  < 0.05. Fusion was defined as <2 degrees of intersegmental motion on flexion/extension radiographs.

Results  The two groups were similar in age and comorbidities. The mean operation time and the mean hospital stay were shorter in the uLP group ( p  = 0.015). The intraoperative blood loss did not exceed 200 mL in both groups. At follow-up, the groups showed comparable clinical outcome data. The sagittal profile did not deteriorate in either group. Fusion rates were 67% in the uLP group and 92% in the LC group. No infections occurred in either group. In the LC group, one patient developed a transient C5 palsy. Revision surgery was required for a malpositioned screw (LC) and for one implant failure (uLP).

Conclusion  Laminoplasty and unilateral fixation via a unilateral approach achieved comparable clinical and radiologic results with laminectomy and bilateral fixation, despite a lower fusion rate. However, the surgical traumatization was less.

The opening size of the laminoplasty is dependent on the groove size: A numerical study

BACKGROUND

The expansion of the cervical vertebrae lamina appears to be crucial to related surgical procedures. The dimensions of the groove influence the strain concentration within the lamina of the vertebra and, thus, the potential success or failure of respective surgical procedure. The aim of this computational study is to clarify both the role of the size of the groove with concern to both the open door and the double door laminoplasty techniques.

METHODS

Finite element models were created via computer tomography with varying lamina groove dimensions. Displacements were applied to the models at the open side of the vertebral arch and the vertebral body was constrained prior to movement along all the axes. The maximal opening size measured on the inner side of the lamina and the percentage increase in the initial spinal areas were subsequently analyzed.

FINDINGS

The elastic strain concentration value was observed for the groove in all cases, while the maximal principal elastic strain concentration value was observed at the opposite side to the groove cut into the lamina, also in all cases. The maximal area increase related to the 4 mm groove accompanied by the preservation of the ventral cortex of the bone.

INTERPRETATION

The study suggested three conclusions a) the wider the groove, the greater is the opening potential, b) the maximal opening size following laminoplasty is not dependent on the depth of the bone cut for this type of groove, c) no benefit accrues in terms of the opening size following the cutting of a supplementary groove at the beginning of the lamina.

Expansion of Spinal Canal with Lift-Open Laminoplasty: A New Method for Compression Cervical Myelopathy

OBJECTIVE

This study is to introduce lift-open laminoplasty and verify the increase of the spinal canal area following this surgical technique according to the preoperative anatomical measurement.

METHODS

There are 82 patients (43 male and 39 female) analyzed in our study from January 2019 to December 2020. The average age was 63.2 ± 3.21 years (from 41 to 84 years). All of them were treated with open-door laminoplasty, with a decompression segment range from C3 to C6. The increase of the spinal canal area after open-door laminoplasty was measured on postoperative CT images of the patients, and the distances between both lamina-facet junctions and lamina length was measured on preoperative CT images. Using the Pythagorean theorem for the equation of calculation area after the expansile open-door laminoplasty. Based on previous measurement parameters, spinous process length, lateral mass width, distance between osteotomy line and lamina-facet junctions line were additionally measured on preoperative CT images. Pythagorean theorem was used for calculating the area after the expansile lift-open laminoplasty. The results were recorded and a statistical analysis was undertaken. Then, there were six patients (five male and one female) treated with lift-open laminoplasty on C6, open-door on C3-C5, who suffer from cervical spondylotic myelopathy from December 2020 to January 2021. The average age was 60.3 ± 1.7 years (from 56 to 71 years). Operation time, blood loss, and Japanese Orthopaedic Association (JOA) score recovery rate were recorded. Intraoperative and postoperative complications were observed.

RESULTS

The increase of the spinal canal area after open-door laminoplasty measured on postoperative CT images was 123.01 ± 17.06 mm² and the calculation of the increase of the spinal canal areausing the Pythagorean theorem after open-door laminoplasty was 122.86 ± 15.86 mm² . A comparison of the actual value with calculative value showed no significant difference (T value = 0.057, P value = 0.955). The calculation of the increase of the spinal canal area after lift-open laminoplasty was 183.57 ± 62.99 mm² , which was larger than that after open-door laminoplasty (T value = 8.462, P value < 0.001). Mean operation time was 153.3 min and operative blood loss was 600 mL of the six patients treated with lift-open laminoplasty. At 1 month follow-up, all patients had recovered well. JOA score recovery rate was 37.6% and no intraoperative and postoperative complications occurred.

CONCLUSION

Lift-open laminoplasty could preserve nearly 100% of extensor muscle, avoid damaging C7 paraspinal muscles and C6-7 posterior muscle-ligament complex, reconstruct the spinous process firmly in the midline, and expand adequate spinal canal area after operation. These advantages could reduce the incidence rate of complications and bring better clinical results than traditional laminoplasty.

Comparison of Spinal Canal Expansion Following Cervical Laminoplasty Based on the Preoperative Lamina Angle : A Simulation Study

OBJECTIVE

Expansion in the spinal canal area (SCA) after laminoplasty is one of the critical factors to relieve the preoperative symptoms. No previous study has compared the increases in SCA achieved by open-door laminoplasty (ODL) and double door laminoplasty (DDL) according to the preoperative lamina angle (LA). This study was designed to clarify the relationship between the laminoplasty opening angle (OA)/laminoplasty opening size (OS) and increases in the SCA following ODL and DDL according to the preoperative LA using a simulation model.

METHODS

The simulation model was constructed and validated by comparing the clinical data of 64 patients who had undergone C3-C6 laminoplasty (43 patients with ODL and 21 patients with DDL). SCA expansion was predicted with a verified simulation model at various preoperative LAs (from 28° to 32°) with different OAs (40° to 44°) and OSs (10 mm to 14 mm) recruited from patient data.

RESULTS

The constructed simulation model was validated by comparing clinical data and revealed a very high degree of correlation (r=0.935, p<0.001). In this validated model, at the same OA, the increase in SCA was higher following ODL than following DDL in the usual LA (p<0.05). At the same OS, the increase in SCA was slightly larger following DDL than following ODL, but the difference was not significant (p>0.05). The difference was significant when the preoperative LA was narrower or much wider.

CONCLUSION

Based on clinical data, a simulation model was constructed and verified that could predict increases in the SCA following ODL and DDL. When applying this model, prediction in SCA increase using the OS parameter was more practical and compatible with clinical data. Both laminoplasties achieved enough SCA, and there was no significant difference between them in the usual range.

Comparison of single versus double door posterior cervical laminoplasty for patients with cervical spondylotic myelopathy: A systematic review and meta-analysis

OBJECTIVE

We undertook a meta-analysis to compare the efficacy and safety of single versus double door posterior cervical laminoplasty for cervical spondylotic myelopathy.

METHODS

PubMed, Embase, and Cochrane Central Register of controlled trials were searched for randomized controlled trials investigating single and double door posterior cervical laminoplasty for cervical spondylotic myelopathy. The Mantel-Haenszel method with the fixed-effects or random-effects model was used to calculate relative risks and 95% confidence intervals (CIs).

RESULTS

Seven studies with 224 patients met the eligibility criteria and were included. There was a significant difference in Japanese Orthopedic Association score (MD = 0.79, 95%CI [0.09, 1.49], P = .03; P for heterogeneity = .09, I = 45%), and adverse events (OR = 0.32, 95%CI [0.11, 0.95], P = .04; P for heterogeneity = 1.00, I = 0%) between the double door posterior cervical laminoplasty group and the single door posterior cervical laminoplasty group. There was no significance in operative time (MD = 0.56, 95%CI [-11.86, 12.98], P = .93; P for heterogeneity = 0.001, I = 73%) and length of hospital stay (OR = -0.75, 95%CI [-1.78, 0.27], P = .15; P for heterogeneity = 1.00, I = 0%) between the 2 groups.

CONCLUSION

Double door posterior cervical laminoplasty is more effective and safer than single door laminoplasty in the treatment of cervical spondylotic myelopathy.

Comparison of the operative time for open door laminoplasty using titanium plate spacers or hydroxyapatite block spacers: a retrospective study

Abstract

Background

Titanium plate (TP) and hydroxyapatite (HA) spacers are widely used during open-door laminoplasty, performed with the patient in a prone position. Reducing operative time is an important consideration, particularly to reduce the risk of postoperative complications in older patients. The purpose of this retrospective cohort study was to compare the operative time for open-door laminoplasty using TP or HA spacers.

Methods

Consecutive patients with a spinal cord injury, without bone injury, and ≥ 50 years of age were included. Multivariate regression analysis was used to compare the operative time between patients in the TP and HA group, adjusting for known factors that can influence surgical and postoperative outcomes. Propensity score matching was used to confirm the robustness of the primary outcome. The cumulative incidence of postoperative complications over 1-year after surgery was also compared.

Results

Of the 164 patients forming our study group, TP spacers were used in 62 and HA in 102. Operative time was significantly shorter for the TP (128 min) than HA (158 min) group (p < 0.001). Both multivariate and propensity score matching analyses confirmed a significant reduction in operative time for the TP, compared to HA, group (regression coefficient, − 30 min and − 38 min, p < 0.001 and p < 0.001, respectively). There was no significant difference in the cumulative incidence of postoperative complications.

Conclusions

The use of TP spacers reduced the operative time for cervical open-door laminoplasty by about 30 min, compared to the use of HA spacers, with no difference in the rate of postoperative complications.

Photogrammetric analysis: An objective measure to assess the craniocervical range of motion after cervical laminoplasty surgeries

Surgical decompression using laminoplasty is commonly performed for multilevel stenosis with cervical spondylotic myelopathy. However, the long-term effects on the craniocervical range of motion (ROM) after surgery are not well understood. This study represents the first entry into the literature of photogrammetric analysis for clinical measurement of craniocervical ROM. All patients underwent a French-door laminoplasty from 1995 to 2016 and were evaluated radiologically and with postoperative photographs (photogrammetric analysis) to measure craniocervical ROM and axial rotation. Radiographic parameters were occiput to C2 angle, C1-2 angle, C2-7 angle/cervical lordosis (CL), T1-slope (T1S), and TS-CL were measured. Chin-brow vertical angle (CBVA) was utilized for flexion and extension, while nose-turn angle (NTA) was used to assess axial rotation. Forty-four patients (mean age: 65.7 years, 50% female) had a mean follow-up of 37.9 months. Mean values in neutral, flexion, and extension were occiput to C2 = 30°, 15°, and 43°; C1-C2 = -32°, -25°, -32°; and C2-C7 = -4°, 11°, -20°, respectively. Mean CL was within 1 SD of the established -17° (±13.86°). Mean T1S and TS-CL were 33° and 30° in the neutral position, respectively. Mean radiographic full range of motion from flexion to extension was 53°. NTA towards patients' left was 48° and the right side was 45°. Mean CBVA, was -4°, mean flexion 37°, and extension -45°; full range was 81°. Global craniocervical ROM has proven to be well preserved for many years following cervical laminoplasty. Photogrammetric analysis is a cost-effective and radiation-free method, accurate for quantitative assessment of craniocervical and cervical ROM.

Clinical Investigation of the Association of Opening Size with Sagittal Canal Diameter Based on Single-Door Cervical Laminoplasty

Background

Many clinical studies have assessed the association of laminoplasty opening size (LOS) with sagittal canal diameter (SCD) based on single-door cervical laminoplasty (SDCL). Nevertheless, the “worn-off” lamina extracted in SDCL was neglected in these reports. We aimed to develop a simple mathematical model to analyze the relationship between the effective LOS and SCD, taking into consideration the worn-off lamina.

Material/Methods

A total of 106 patients treated by SDCL at our hospital were included in this study. Pre-operative and post-operative SCDs were assessed using a picture archiving and communication system (PACS) based on computed tomography scans. Mini-plate sizes as well as drill bit diameters were recorded in detail in order to determine the effective LOS for each vertebral lamina involved.

Results

SCD in all patients was increased significantly after SDCL (P<0.01). A linear correlation was found between effective LOS and the post-operative SCD increment from C3 to C7 (R²>0.933, P<0.001). The 12 mm mini-plate was most often used in SDCL, accounting for 64.45% of all cases, whereas 10 mm and 16 mm mini-plates were the least used, accounting for 3.85% and 3.00%, respectively.

Conclusions

There is a strong linear correlation between effective LOS and the post-operative SCD increment. The SCD was increased by about 0.5 mm per mm increase in effective LOS. Thus, post-operative SCD could be precisely calculated and predicted, enabling the selection of optimal mini-plate prior to SDCL.

The Dural Tube Continues to Expand after Muscle-Preserving Cervical Laminectomy

Introduction

The purpose of this study was to elucidate the duration for which the dural tube continues to expand after muscle-preserving cervical laminectomy and the extent to which the expansion affects surgical outcomes.

Methods

We analyzed 83 patients with cervical myelopathy who underwent muscle-preserving selective laminectomy of three consecutive laminae between C4 and C6. On the lateral radiographs, parameters considered were C2-7 Cobb angles, range of flexion-extension neck motions, and C2-7 sagittal vertical axis. Neck alignment was classified into four types with lateral radiographs. Anteroposterior (AP) diameter of the dural tube was measured at mid-level of the C5 vertebral body on T2 sagittal image. Expansion ratio (ER) was defined as the extent of expansion at a particular time divided by the final extent of expansion of the dural tube diameter. Operative outcomes were examined using the Japanese Orthopaedic Association scores.

Results

The mean age was 62.3 years, and the mean follow-up period was 2 years and 9 months. AP diameter of the dural tube had been expanding until 1-year after surgery. ER in cases with kyphosis was lower at 6 months than that in cases without kyphosis, indicating that the speed of dural expansion was slower in cases with kyphosis. There was no correlation between the extent of expansion of the dural tube and neurological recovery.

Conclusions

The dural tube continued to expand for approximately 1-year after surgery. The dural tube of patients with kyphosis slowly expanded possibly because of the hardness of the dura mater. A small extent of dural expansion does not necessarily indicate bad surgical outcomes.

Short-Term Clinical Evaluation of Enhanced Unilateral Open-Door Laminoplasty Using Titanium Mesh

Study Design

Observational, cross-sectional study.

Purpose

The purpose of this study was to evaluate the clinical efficacy and safety profile of open-door laminoplasty (ODL) using titanium mesh.

Overview of Literature

The most appropriate surgical management of degenerative spine disorders, particularly ossification of the posterior longitudinal ligament, remains controversial and continues unabated in the neurosurgical community. However, recently, ODL has become popular among surgeons. Many modifications have been developed since Hirabayashi in 1983 to enhance the clinical efficacy and safety of this procedure.

Methods

We reviewed the obtained data of patients with ossification of the posterior longitudinal ligament (OPLL) who underwent ODL using titanium mesh at Neurosurgery Subdivision, the Dr. Sardjito Hospital, Yogyakarta, Indonesia, during January 2013–December 2015. Motor improvement (Nurick score), axial neck pain (neck disability index [NDI]), and incidence of complications were pre- and postoperatively examined, and the clinical efficacy and safety of the procedure was evaluated. Data were analyzed using Wilcoxon signed-rank test and paired t-test.

Results

This study included five patients were included (i.e., four males and one female) with mean age of 47.00±9.68 years, where reassessments were done after mean follow up of 20.2±4.74 months. Mean duration of surgery was 165±12.55 minutes. Pre- and postoperative motor assessments were 3.4±1.52 and 2.0±1.22 (p =0.059), respectively. Axial neck pains using NDI were 23.60±7.44 and 12.40±6.50 (p =0.004) before and after operations, respectively. No infected postoperative scar was found, and only one patient had a left C5 motor palsy.

Conclusions

The results of the present study suggest that enhanced ODL using titanium mesh has favorable outcome and safety profile, which can pave the way for a suitable treatment in patients with OPLL.

Impact of different laminae open angles on axial symptoms after expansive open-door laminoplasty

The present study is a retrospective study.Axial symptoms are frequently encountered complication after laminoplasty. Some studies have reported the influencing factors and preventive measures of axial symptoms after laminoplasty. However, impact of different laminae open angles on the postoperative axial symptoms remains unclear.The objective of the present study was to explore the effect of different laminae open angles on postoperative axial symptoms and to discuss the possible mechanisms of the impact of different open angles on axial symptoms.We retrospectively analyzed 124 patients with multilevel cervical compression myelopathy who were treated with expansive open-door laminoplasty from February 2012 to January 2015. The operational level ranged from C3-C7 in all patients. The laminae open angles at the C4, C5, and C6 levels were measured 1 week postoperative. The mean value was taken for statistical analysis. The patients were divided into 2 groups, group A (open angles < 40°, 71 patients including 44 males and 27 females) and group B (open angles ≥ 40°, 53 patients including 32 males and 21 females). C2-C7 Cobb angle, range of cervical motion (ROM), Japanese Orthopedic Association (JOA) score, and visual analog scale (VAS) score for axial pain were compared between the 2 groups.All patients completed at least 2-year follow-up. Both groups gained significant JOA improvement postoperatively (P < .05). Preoperative and postoperative C2-C7 Cobb angle and ROM comparisons were significantly different (P < .05) in both groups. There were no significant difference for other clinical and radiography parameters between the groups (P > .05). At 2 weeks and 6 months after surgery, there was significant difference in axial symptoms between the 2 groups (P < .05). At final follow-up, the difference between the 2 groups was not statistically significant (P > .05).In different angles of the lamina open-door, incidence of axial symptoms has statistically difference between the 2 groups. When the lamina open-door angles are <40°, there are not only ensure adequate spinal cord decompression but reduces the incidence of early and midterm postoperative axial pain.

Factors associated with postoperative C5 palsy after expansive open-door laminoplasty: retrospective cohort study using multivariable analysis

PURPOSE

The aim of the present study was to investigate the factors associated with C5 palsy by focusing on radiological parameters using multivariable analysis.

METHODS

The authors retrospectively assessed 190 patients with cervical spondylotic myelopathy treated by open-door laminoplasty. Four radiographic parameters-the number of expanded lamina, C3-C7 angle, lamina open angle and space anterior to the spinal cord-were evaluated to clarify the factors associated with C5 palsy.

RESULTS

Of the 190 patients, 11 developed C5 palsy, giving an overall incidence of 5.8%. Although the number of expanded lamina, lamina open angle and space anterior to the spinal cord were significantly larger in C5 palsy group than those in non-palsy group, a multiple logistic regression analysis revealed that only the space anterior to the spinal cord (odds ratio 2.60) was a significant independent factor associated with C5 palsy. A multiple linear regression analysis indicated that the lamina open angle was associated with the space anterior to the spinal cord and the analysis identified the following equation: space anterior to the spinal cord (mm) = 1.54 + 0.09 × lamina open angle (degree). A cut-off value of 53.5° for the lamina open angle predicted the development of C5 palsy with a sensitivity of 72.7% and a specificity of 83.2%.

CONCLUSIONS

The larger postoperative space anterior to the spinal cord, which was associated with the lamina open angle, was positively correlated with the higher incidence of C5 palsy.

A New Fixation Technique for French-Door Cervical Laminoplasty: Surgical Results With a Minimum Follow-up of 6 Years

DESIGN

A case series of 5 patients with multilevel cervical myelopathy treated by French-door cervical laminoplasty (FDCL) and use of unicortical iliac crest graft as spacer fixed with titanium miniplates and screws is described.

OBJECTIVE

To report a minimum of 6-year follow-up results of our new plate-screw fixation technique for FDCL.

SUMMARY OF BACKGROUND DATA

Hardware-assisted laminoplasty has the potential advantage of preventing restenosis by holding the laminar door "open" while healing progresses and also prevents spacer dislodgement. The use of titanium miniplates as internal fixation device for FDCL by our novel technique has not been reported.

METHODS

Five patients suffering from multilevel cervical myelopathy harboring constitutionally narrow cervical canal (3) and multilevel cervical spondylotic myelopathy (2) who underwent 2-3 level FDCL and followed up prospectively for 6 years is presented. Modified Kurokawa and colleague's technique of FDCL was performed and autologous iliac crest bone graft was interposed between the sagittaly split spinous processes. A 12- to 15-hole titanium miniplate was contoured into a trapezoidal shape to sit flush with the posterior elements. The plate was anchored to bone graft and posterior elements with screws and patients mobilized without any external orthosis.

RESULTS

The mean follow-up was 90.5 months. The mean improvement in Neck disability index at final follow-up was 35% and mean improvement in Visual analog scale was 4 points. Japanese orthopaedic association score improved from a mean of 10 to a mean of 14.8 postoperatively. The final outcome was good (3) and excellent (2) by Odom's criteria. All patients improved to Nurick's grade 0 or I and reported significant relief from their myelopathic symptoms and axial neck pain. There were no postoperative hardware-related complications or pseudoarthrosis.

CONCLUSIONS

Titanium miniplates are excellent devices for stabilizing the interspinous spacers used in FDCL. They prevent cervical canal deformation, restenosis, spacer dislodgement and are durable, cost-effective in facilitating early mobilization at intermediate-term follow-up of 6 years.

Clinical outcome and safety study of a newly developed instrumented French-door cervical laminoplasty technique

Background

Standard laminectomy for treatment of cervical myelopathy is associated with secondary instability and kyphosis, while laminectomy combined with fusion puts adjacent segments at risk of degeneration. Single- and double-door laminoplasty techniques have been developed to overcome these limitations. More recently, complications related to bone graft dislodgment have fostered development of hardware-augmented laminoplasty techniques. The aim of this study is to review the clinical safety and effectiveness of a newly developed technique of instrumented French-door laminoplasty for treatment of cervical myelopathy.

Materials and methods

A series of 25 consecutive myelopathic patients were treated with a novel instrumented cervical French-door laminoplasty technique, whereby the enlarged posterior arch was held open with maxillofacial plates and screws. Patients had pre- and postoperative assessments with the Neck Disability Index (NDI), Japanese Orthopaedic Association (JOA) Score, Visual Analogue Score and radiographs. Minimum follow-up was 40 months, with regular interval assessments.

Results

There were 18 males with a mean age of 45 years. The mean operative time was 145 min. The average hospital stay was 2.4 days and the mean follow-up was 56.5 months (40–72). All patients reported neurological improvements and there was a 35% improvement in NDI, and JOA score improved by 4.8 points. No postoperative hardware-related complications were noted and only one case of temporary C5 palsy, which completely resolved by the one-year follow-up.

Conclusions

Our data and clinical experience demonstrate that this hardware-augmented laminoplasty technique is safe and effective. We observed no hardware-related complications in our series. The use of readily available maxillofacial titanium miniplates and ease of surgical procedure means that this technique can be easily adopted into clinical practice.

Level of evidence

Level IV.

Factors that regulate spinal cord position after expansive open-door laminoplasty

INTRODUCTION

Although appropriate dorsal migration of the spinal cord is a desired end point of cervical laminoplasty, it is difficult to predict in advance the spinal cord position after surgery and to control it during surgery. The aim of the present study was to investigate the factors that affect postoperative spinal cord position after cervical laminoplasty using multivariable analysis.

MATERIALS AND METHODS

We retrospectively assessed 56 consecutive patients with cervical spondylotic myelopathy treated by open-door laminoplasty. The postoperative anterior space of the spinal cord was measured at 204 levels, and its maximum value was measured at 56 levels within the decompressed area. To identify the factors that regulate the postoperative spinal cord position, we evaluated seven radiological parameters, including the C3-C7 lordosis angle (LA), LA of the decompressed area, C3-C7 spinal cord lordosis angle (SCLA), SCLA of the decompressed area, spinal canal sagittal diameter at C5, number of expanded lamina, and postoperative dural sac diameter.

RESULTS

The postoperative anterior space of the spinal cord was 5.5 ± 1.4 mm, and its maximum value was 6.4 ± 1.3 mm. A multiple linear regression analysis revealed that the number of expanded laminae (standardized partial regression coefficient: β = 0.17, p = 0.009) and dural sac diameter (β = 0.43, p < 0.001) was significantly associated with anterior space of the spinal cord. Although these parameters were also significantly associated with the maximum value, their relative contributions were reversed; β = 0.49 (p < 0.001) for the number of expanded laminae and 0.25 (p = 0.029) for the dural sac diameter.

CONCLUSIONS

The number of expanded laminae and dural sac diameter was significantly associated with the spinal cord position after laminoplasty. These factors could help to predict spinal cord position following laminoplasty and achieve adequate indirect decompression of the spinal cord.

Single-door cervical laminoplasty using titanium miniplates alone

PURPOSE

To review outcome of 29 patients who underwent single-door cervical laminoplasty for myelopathy using titanium miniplates alone.

METHODS

Records of 20 men and 9 women aged 35 to 79 (mean, 64.3) years who underwent single-door cervical laminoplasty for myelopathy using titanium miniplates alone were reviewed. A total of 125 laminae were opened; 97 of them were fixed with a titanium miniplate. In 19 patients, a 20-hole titanium miniplate bent to the contour of a lamina was used and fixed into 3 laminae at alternate levels. In the remaining 10 patients, the pre-contoured ARCH Laminoplasty System was used and fixed into all laminae. In most patients, screw fixation was unicortical, and no spacer or bone graft was used.

RESULTS

The mean follow-up duration was 4 (range, 2-9) years. At one-year follow-up, the mean Japanese Orthopaedic Association (JOA) score improved from 9.2 to 13.2 (p<0.001). The mean JOA recovery rate was 64%. No patient had neurological deterioration. The mean anteroposterior diameter increased from 14.3 mm to 19.7 mm; the mean increase was 6.1 mm in the plated laminae and 5.3 mm in the unplated laminae (p=0.11). Out of the 125 laminae, there were 2 hinge non-unions in the unplated laminae, and 2 screw pullouts (not associated with plate loosening). No patient had penetration into the vertebral foramen or neuroforamen. Spring-back closure occurred in 5 (18%) of the 28 unplated laminae, with a mean of <3 mm loss of the initial expansion. Two patients developed transient C5 palsy presenting as shoulder abduction weakness. One patient had a delayed dural tear due to a sharp spike at the edge of the opened C6 lamina.

CONCLUSION

Single-door cervical laminoplasty using miniplates alone is a safe technique and achieves a high hinge union rate, good canal expansion, and neurological recovery.

Relationship between the laminoplasty opening size and the laminoplasty opening angle, increased sagittal canal diameter and the prediction of spinal canal expansion following open-door cervical laminoplasty

OBJECTIVE

To clarify the relationship between the laminoplasty opening size (LOS), the laminoplasty opening angle (LOA) and the increase in sagittal canal diameter (SCD) and to predict the amount of canal enlargement during open-door cervical laminoplasty (ODCL).

METHODS

Formula describing the relationship between LOS and LOA, the increase in SCD was deduced. The parameters of pre- and postoperative computed tomography scans of 36 patients who had undergone laminoplasty surgery were measured by picture archiving and communication system (PACS) software, and the amount of canal enlargement of these patients was predicted when the opening size of laminoplasty was 8, 10, 12, 14 and 16 mm according to the formula.

RESULTS

For equivalent LOS, the amount of canal enlargement with each opening size differed throughout the cervical region. When the C3-C7 LOS was 10 mm the SCD increased >4.1 mm, and the canal area increased in C3-C6 >88 mm(2), and the canal area increased in C7 > 80 mm(2). When the C3-C7 LOS was 12 mm, the SCD increased >5.2 mm, and the canal area increased in C3-C6 >104 mm(2), and the canal area increased in C7 > 94 mm(2).

CONCLUSION

Formula accurately showed the relationship between the LOS and the increase in SCD achieved by ODCL. The amount of canal enlargement following ODCL could be predicted by the formula. LOS of 10-12 mm at C3-C7 might be optimal during ODCL.

Open-door versus French-door laminoplasty for the treatment of cervical multilevel compressive myelopathy

Open-door laminoplasty (ODL) and French-door laminoplasty (FDL) are used to treat cervical multilevel compressive myelopathy. However, differences in outcome between the approaches remain unknown. To investigate treatment differences, we performed a systematic review and meta-analysis. Four comparative trials were identified and analyzed in the review. The results showed that ODL had a higher postoperative Japanese Orthopaedic Association (JOA) score than FDL (weighted mean difference [WMD]=0.83; 95% confidence interval [CI]: 0.47 to 1.19; p<0.01). There were no significant differences between the two methods in terms of operative time (WMD=-6.76; 95% CI: -21.70 to 8.18; p=0.38), intraoperative blood loss (WMD=41.70; 95% CI: -61.43 to 144.82; p=0.43), total complication rate (OR=2.43, 95% CI: 0.22 to 27.04; p=0.47), postoperative C5 palsy (OR=1.97, 95% CI: 0.46 to 8.39; p=0.36), postoperative cervical lordosis (WMD=-0.60; 95% CI: -0.37 to 1.86; p=0.63) or range of motion (WMD=-4.62; 95% CI: -13.06 to 3.82; p=0.28). These results suggest that neither cervical laminoplasty approach is superior to the other based on the postoperative radiological data and complication rate, although ODL had higher postoperative JOA score than FDL.

The relationship between laminoplasty opening angle and increased sagittal canal diameter and the prediction of spinal canal expansion following double-door cervical laminoplasty

PURPOSE

To clarify the relationship between laminoplasty opening angle (LOA) and the increase in sagittal canal diameter (SCD) in double-door cervical laminoplasty (DDCL) and to predict the increase in SCD using the resulting formula.

METHODS

We analyzed 20 patients with multilevel cervical spondylotic myelopathy who underwent DDCL between September 2010 and January 2013. The pre- and post-operative parameters of the cervical spinal canal were measured by computed tomography. We deduced a formula describing the relationship between LOA and the increase in SCD and used it to predict the increase in SCD of these patients as LOA increased.

RESULTS

When the C3-C7 LOA was 25°-45°, the magnitude of the increase in SCD was notable (increases of 3.08-5.6 mm compared with the pre-operative SCD). When the C3-C7 LOA was more than 45°, the magnitude of the increase in SCD was relatively smaller; the increase in C3-C7 SCD with a 55° LOA was merely 0.4 mm more than with a 45° LOA. When LOA was 30° at C3-C6 or 40° at C7, the increase in SCD was more than 4 mm. When the C3-C6 LOA was 40°, SCD increased by more than 5 mm.

CONCLUSIONS

The formula accurately showed the relationship between LOA and the increase in SCD in DDCL. Based on the LOA, increases in SCD following C3-C7 laminoplasty can be accurately predicted using this formula. This enables DDCL based on accurate individual LOAs, which prevents inadequate or excessive opening.

Is the Cross-sectional Area after Unilateral Open Door Laminoplasty Wider than that after Midline Splitting Laminoplasty ? : Mathematical Approach

Objective

The aim of this study was to compare geometrically cross-sectional areas of two different laminoplasty techniques in same opening size.

Some investigators have studied the expanded areas of the two different techniques using imaging study. Although it is unclear that postoperative spinal canal is correlated with the surgical outcome we just focused on mathematical and geometrical correlation of the expandable area with surgical opening size in different laminoplasty techniques.

Methods

To predict the expandable area by a midline splitting technique and a unilateral open door technique, we placed an imaginary isosceles triangle in the spinal canal and drew graphs for the equation of the expandable areas in same opening size using the Pythagorean theorem and mathematical program. To substitute the constant figures of mathematical formula we estimated the normal cervical spine CT scans of 50 Korean adults.

Results

We subtracted the imaginary triangle from the spinal canal and were left with the remaining area of the spinal canal that was not changed before and after surgery. In same opening size the expandable area by the midline splitting technique was same but slightly wider than the unilateral open door technique, irrespective of the triangular shape. For a normal isosceles triangle the results were the same.

Conclusion

Using mathematical proof, the expandable area after the midline splitting technique was same but slightly larger than that after the unilateral open door technique, irrespective of the size of the lamina opening.

Preoperative design of expansive open-door laminoplasty: a computer-assisted morphometric analysis

Whereas the expansive open-door laminoplasty (EL) has been applied widely and the bone gutter on the hinge side is essential for EL, little is known regarding the mandatory width of the bone gutter. This study addressed the essential parameters of bone gutters for EL. Preoperative axial CT images of 20 patients suffering from cervical myelopathy were downloaded and entered into a computer. EL was then simulated using a computer-assisted technique and the thickness of the laminae at the gutter sites was measured. Accordingly, the width of the bone gutter was linked mathematically with the angle of the lifted lamina and the thickness of the lamina at the lamina-lateral mass junction. Furthermore, the average thickness of the laminae at the gutter site was 6.19 mm, and the appropriate bone gutter for EL was 5.13 to 7.15 mm. The width of the bone gutter can thus be planned precisely preoperatively, which may help improve the safety and accuracy of expansive open-door laminoplasty.