Identification of milling status based on vibration signals using artificial intelligence in robot-assisted cervical laminectomy

BACKGROUND

With advances in science and technology, the application of artificial intelligence in medicine has significantly progressed. The purpose of this study is to explore whether the k-nearest neighbors (KNN) machine learning method can identify three milling states based on vibration signals: cancellous bone (CCB), ventral cortical bone (VCB), and penetration (PT) in robot-assisted cervical laminectomy.

METHODS

Cervical laminectomies were performed on the cervical segments of eight pigs using a robot. First, the bilateral dorsal cortical bone and part of the CCB were milled with a 5 mm blade and then the bilateral laminae were milled to penetration with a 2 mm blade. During the milling process using the 2 mm blade, the vibration signals were collected by the acceleration sensor, and the harmonic components were extracted using fast Fourier transform. The feature vectors were constructed with vibration signal amplitudes of 0.5, 1.0, and 1.5 kHz and the KNN was then trained by the features vector to predict the milling states.

RESULTS

The amplitudes of the vibration signals between VCB and PT were statistically different at 0.5, 1.0, and 1.5 kHz (P < 0.05), and the amplitudes of the vibration signals between CCB and VCB were significantly different at 0.5 and 1.5 kHz (P < 0.05). The KNN recognition success rates for the CCB, VCB, and PT were 92%, 98%, and 100%, respectively. A total of 6% and 2% of the CCB cases were identified as VCB and PT, respectively; 2% of VCB cases were identified as PT.

CONCLUSIONS

The KNN can distinguish different milling states of a high-speed bur in robot-assisted cervical laminectomy based on vibration signals. This method is feasible for improving the safety of posterior cervical decompression surgery.

A case of anterior arch fracture of the atlas associated with C1 laminectomy

Background

Spontaneous anterior arch fracture of the atlas after a C1 laminectomy (CIL) is an extremely rare complication.

Case Description

A 72-year-old male presented with the sudden onset of neck pain. His prior history included; a CIL for atlantoaxial subluxation, shunt closure for a spinal dural arteriovenous fistula at C3, a cervical laminoplasty from C3 to C6 for stenosis, and a prior anterior C4/5 and C5/6 fusion 14 years ago. Once the computed tomography documented a right C1 anterior arch fracture, and occipital-cervical fusion was performed utilizing C2 laminar screws and C4 pedicle screws with halo-vest placement. Postoperatively, the neck pain resolved and he remained stable.

Conclusion

Neurosurgeons should be aware of the risk of anterior arch fractures following a CIL and may alternatively consider a C1 laminoplasty in the future.

Iatrogenic giant pseudomeningocele of the cervical spine: A case report

BACKGROUND

Only a few cases of giant pseudomeningoceles have been reported in the literature. Herein, we report a giant pseudomeningocele of the cervical spine that was found after cervical laminectomy for an epidural hematoma following epidural blockade.

CASE SUMMARY

A 47-year-old man presented with recurrent neck pain and posterior neck swelling after spinal surgery. Magnetic resonance imaging of the cervical spine revealed fluid collection (5.6 cm × 6.6 cm × 11.2 cm) at the C3-6 level; this proved to be a pseudomeningocele. Symptoms related to the pseudomeningocele resolved following dural repair and fat graft transplantation.

CONCLUSION

Although rare, pseudomeningocele is a possibility in patients with recurrent back pain, radicular pain, or a persistent headache following spinal surgery. Continuous attention should be paid throughout the spinal procedure, whether conservative or non-conservative.

Ten-Step Minimally Invasive Cervical Decompression via Unilateral Tubular Laminotomy: Technical Note and Early Clinical Experience

BACKGROUND

Minimally invasive techniques utilizing tubular retractors have become an increasingly popular approach to the spinal column. The concept of a unilateral laminotomy for bilateral decompression (ULBD), first applied in the lumbar spine, has recently been applied to the cervical spine for the treatment of cervical spondylotic myelopathy (CSM). A better understanding of the indications and surgical techniques is required to effectively educate surgeons on how to appropriately and safely perform tubular cervical laminotomy via ULBD.

OBJECTIVE

To describe a 10-step technique for minimally invasive cervical laminotomy and report our early clinical experience.

METHODS

A retrospective review identified 15 patients with CSM who were treated with this procedure. Visual analogue scale (VAS), neck disability index (NDI), and modified Japanese Orthopaedic Association (mJOA) scores were obtained pre- and postoperatively.

RESULTS

The mean age of the 15 patients was 73.1 ± 6.8 yr. The median number of levels treated was 1 (range 1-3). Mean operative time was 125.3 ± 30.8 or 81.7 ± 19.2 min per level. Mean estimated blood loss was 57.3 ± 24.6 cc. Median postoperative hospital length of stay was 36 h. No complications were encountered. Median follow-up was 18 mo. Mean pre- and postoperative VAS were 6.4 ± 2.4 and 1.0 ± 0.8, respectively (P < .001). Mean pre- and postoperative NDI were 46.4 ± 19.2 and 7.0 ± 6.9, respectively (P < .001). Mean pre- and postoperative Mjoa were 11.3 ± 2.5 and 14.5 ± 0.5, respectively (P < .001).

CONCLUSION

In our early clinical experience, minimally invasive cervical ULBD is safe and effective. Adherence to the presented 10-step technique will allow surgeons to safely address bilateral cervical pathology while avoiding complications.

Less Invasive Cervical Decompression via Unilateral Tubular Laminotomy Using 3-Dimensional Total Navigation: 2-Dimensional Operative Video

This video demonstrates the step-by-step surgical technique for a less invasive cervical unilateral laminotomy for bilateral decompression (cervical ULBD). This technique allows surgeons to address bilateral cervical pathology while minimizing approach-related complications.1 In the video, we present the case of a 72-yr-old female patient with a past medical history of C3-C4 anterior cervical discectomy and fusion who presented in clinic with persistent posterior spinal cord compression and signal change. The patient had bilateral hand numbness, weakness, poor dexterity, and a positive Hoffman's sign. The patient was treated via a C3-C4 less invasive cervical ULBD using a mobile 3-dimensional (3D) C-arm (Ziehm Vision RFD 3D®, Nürnberg, Germany) combined with 3D computer navigation. Patient consent was obtained prior to performing the procedure. Contrary to anterior techniques, posterior cervical approaches avoid potential dysphasia, recurrent laryngeal nerve injury, and adjacent segment degeneration. Furthermore, the less invasive cervical ULBD results in decreased pain and postoperative narcotic usage, shorter hospital stays and fewer infections compared to open approaches, as well as a lower risk for postlaminectomy kyphosis and deformity, since it requires less muscle disruption and bony removal. Additionally, the use of total 3D navigation facilitates the workflow and minimizes radiation exposure.

Review of laminoplasty versus laminectomy in the surgical management of cervical spondylotic myelopathy

Background:

We reviewed the literature comparing the indications/efficacy of laminectomy (LA) with or without fusion versus laminoplasty (LP) in the treatment of cervical spondylotic myelopathy (CSM).

Methods:

We identified 14 studies in PubMed/Medline to include in our analysis. Outcomes were assessed utilizing the Japanese Orthopaedic Association (JOA) score, visual analog scale (VAS), Neck Disability Index, and Nurick scale. Variables studied included ossification of the posterior longitudinal ligament (OPLL), cervical range of motion (ROM), the C2-C7 sagittal Cobb angle, the Ishihara index, and the Hirabayashi scale. Patients with cervical trauma/fracture, infection, or tumor were excluded from the study.

Results:

In these 14 studies, there were no significant differences between LA and LP groups in terms of preoperative versus postoperative: JOA scores (e.g., including the improvement rate), VAS scores, and ROM. However, the LA patients demonstrated greater postoperative cervical lordosis versus those in the LP group.

Conclusion:

At present, there are no guidelines for choosing LA versus LP for treating CSM. Factors that should be considered when choosing one procedure over the other should include the patients’ preoperative clinical status, the type of CSM, the pathological extent of OPLL, and whether there is a sufficient cervical lordotic curvature.

Spinal cord glioblastoma during pregnancy: Case report

Spinal Cord Glioblastoma Multiforme (SCGBM) is a very rare, debilitating and often fatal tumor. Cases of intracranial GBM during pregnancy have been reported, and as other tumor occurring in this setting, it harbors a great dilemma to attending physicians and families. We report the first case of a SCGBM diagnosed during pregnancy and discuss its management and treatment.

Laminectomy versus open-door laminoplasty for cervical spondylotic myelopathy: A clinical outcome analysis

Background

Cervical spondylotic myelopathy (CSM) is one of the most common diseases in the geriatric population. Decompressive laminectomy or laminoplasty is the predominant surgical procedure of choice, but there remains debate as to which procedure is optimal for managing CSM.

Methods

Here, we retrospectively analyzed 64 patients with CSM undergoing laminectomy (39 patients) versus laminoplasty (25 patients). The data were collected included respective Japanese orthopedic association (JOA) scores, Nurick grades, and Visual analog scale (VAS) values preoperatively versus 12 months postoperatively.

Results

The JOA score after 1 month improved in both groups utilizing laminectomy or laminoplasty. However, at 12 postoperative months, the JOA scores and Nurick grades showed greater improvement following laminoplasty, despite no differences in postoperative pain and complication rates.

Conclusion

Patients with cervical spondylotic myelopathy undergoing laminoplasty (25 patients) showed better 12-month postoperative outcomes (JOA scores and Nurick grades) versus those having laminectomies (39 patients).

How I do it: en-bloc subaxial cervical laminectomy using a high-speed drill with a footplate attachment

BACKGROUND

Cervical laminectomy is a common strategy to decompress the spinal canal.

METHODS

The anatomy of the cervical spine and surrounding critical structures as viewed from the posterior approach is described. The use of a high-speed drill with a footplate attachment to make laminar troughs with an en-bloc subaxial cervical laminectomy is described with a discussion on surgical technique and complication avoidance.

CONCLUSION

This technique allows for a safe, comfortable, and rapid decompression of the cervical spine with minimal risk. For routine cases, this may potentially be more safe and cost-effective than using a cutting bur or bone scalpel attachment.

A Case of Spinal Cord Compression Due to Paraspinal Musculature After Cervical Laminectomy

BACKGROUND

Only a few cases of spinal cord compression after cervical laminectomy have been reported.

CASE DESCRIPTION

We report a case of tetraparesis after executing a C3-C6 anterior and posterior decompression and fusion. Cervical magnetic resonance imaging demonstrated a spinal cord compression due to the impingement of the paraspinal muscles through the laminectomy. The patient experienced a spontaneous neurological recovery and the follow-up cervical magnetic resonance imaging showed resolution of the spinal cord compression.

CONCLUSIONS

This rare complication should be considered among the others after executing a cervical laminectomy.

Post-operative emergence of acute brachial neuritis following posterior cervical laminectomy with fusion: A case report and review of the literature

Introduction

Idiopathic brachial plexus neuritis or neuralgic amyotrophy is a rare neurological condition whose true etiology currently remains unknown. Epidemiologically, the incidence of this condition is exceptionally rare with only 1.6 cases for every 100,000 people (Turner and Parsonage, 1987). Symptoms present an initial acute and sudden pain to the shoulder girdle and upper arm which is followed by a sense of profound weakness and numbness to the upper arm (Parsonage and Turner, 1948). Localized neuropathy within the arm-pit region may also be presented. The pain often exacerbates upon movement of the shoulder. Due to the anatomic location affected and the nature of the clinical symptoms presented, accurate diagnosis of brachial plexus neuritis poses a challenging diagnostic task for physicians due to remarkably similar symptoms expressed by differential diagnoses.

Presentation of case

Here, we report the case of a 55-year-old woman who underwent surgery entailing cervical laminectomy with instrumented fusion. She presented with postoperative symptoms of severe pain in the left arm with significant weakness within 24 h after surgery. A diagnosis of brachial plexus neuritis was made based on the symptoms presented and upon review of imaging scans.

Discussion

After a six-month follow-up visit, the patient recovered from the brachial neuritis but has residual numbness in the hand. The presentation of this case serves to transmit three fundamental purposes. First, this case serves to establish an intriguing possible association of the post-surgical period of cervical laminectomy with acute brachial neuritis and signifies the importance post-operative linkage with brachial neuritis in general. Second, this case also highlights the importance of close clinical monitoring of patients with unique symptoms within the postoperative follow-up period to ensure successful improvement and accurate diagnosis.

Conclusion

As an underdiagnosed and relatively obscure condition, this case serves as an imperative reference for physicians to illuminate differential diagnosis of similar symptomatic conditions and also to promote knowledge of brachial plexus neuritis which can lead to an early and precise diagnosis.

The Efficacy of Posterior Cervical Laminectomy for Multilevel Degenerative Cervical Spondylotic Myelopathy in Long Term Period

Study Design:

This was a retrospective analysis.

Background:

Surgical decompression is the gold standard for preventing the progression of neurological deficit in degenerative multilevel cervical spondylotic myelopathy (CSM). The efficacy of posterior laminectomy in the surgical management of CSM has been described in the past, but long-term follow-up data are scanty.

Objective:

The aim of this study is to assess the long-term clinical-radiological outcomes following posterior cervical decompressive laminectomy in multilevel degenerative CSM.

Materials and Methods:

A retrospective analysis of 110 patients with degenerative multilevel CSM who underwent posterior cervical laminectomy alone in a single hospital by a single surgeon from 2009 to 2013 with minimum 5-year follow-up. Pre- and post-operative clinical parameters (visual analog scale [VAS], Nurick and modified Japanese orthopedic association [mJOA]), radiological parameter (Sagittal cervical Cobb's Angle), perioperative complications (time, blood loss, and hospital stay), postoperative complications (infection, C5 palsy, and neurological worsening) were evaluated.

Results:

Totally 110 patients (males – 68 and females – 42) with age varying from 46 to 80 (mean-57) years, and the mean duration of illness was 3 months were evaluated. Mean clinical parameters are VAS (preoperative = 5 ± 1.31, postoperative = 1.49 ± 0.687), Nurick grading (preoperative = 3.23 ± 71, postoperative = 1.924 ± 0.75), and mJOA (preoperative = 6.32 ± 0.87, postoperative = 9.89 ± 1.37). The mean blood loss was 93.95 ± 19.18 ml, and the mean time taken for surgery was 83.65 ± 10.18 min. About 13% (n = 15) patients developed cervical kyphosis and 29% (n = 32) developed changes in cervical spine alignment and 10% (n = 11) developed worsening of neurology at final follow-up. Two patients developed a superficial infection which was managed with antibiotics. Three patients developed C5 palsy which recovered with due time.

Conclusions:

With the proper selection of patients, posterior cervical laminectomy is effective in offering a clinical improvement to patients with degenerative multilevel CSM with a low incidence of clinically significant radiological deterioration.

Symptomatic cord compression by paraspinal musculature following cervical laminectomy: rare complication

PURPOSE

Cervical laminectomy is an effective treatment for multilevel cervical compressive myelopathy. Symptomatic spinal cord compression (SSCC) by paraspinal musculature (PSM) following cervical laminectomy is rarely reported. The aim of this study was to evaluate the frequency and pathogenesis of this complication after cervical laminectomy.

METHODS

Between 2007 and 2016, the medical records of 1309 cervical laminectomy patients were reviewed. From these 1309 records, seven patients (five men and two women; average age, 64.12 years; range 48-78 years) with SSCC by PSM following cervical laminectomy were identified. The incidence and possible risk factors of this rare condition were evaluated.

RESULTS

The frequency of SSCC by PSM following cervical laminectomy was 0.53%. Presenting symptoms included paralyses and paresthesias, depending on the level and severity of cervical spinal cord compression. The initial onset of neurologic deterioration varied from 12 h to 21 days after operation. Most patients recovered well after surgical management with an average Barthel index of 74.3 at 6 months after surgery. In comparison with 63 controls, this rare complication was associated with preoperative cervical kyphosis, prior antiplatelet therapy, and posterior decompression with prone position.

CONCLUSIONS

SSCC by PSM is a rare but devastating complication following cervical laminectomy, especially in those patients with preoperative kyphosis, prior antiplatelet treatment, and decompression with prone position. MRI is an ideal tool to identify this complication. Rapid cervical cord decompression and avoidance of recurrent compressive events can achieve a good clinical outcome. These slides can be retrieved under Electronic Supplementary Material.

Cervical Laminectomy with Lateral Mass Screw Fixation in Cervical Spondylotic Myelopathy: Neurological and Sagittal Alignment Outcome: Do We Need Lateral Mass Screws at each Segment?

BACKGROUND

Anterior cervical decompression and fusion is the standard procedure used for treating patients with cervical myelopathy. However, these procedures are associated with complications such as pseudarthrosis, construct failure, and neurological complications. Posterior cervical laminectomy and instrumentation is an alternative procedure to treat multilevel cervical myelopathy. In this study, we raised questions whether instrumentation is required at all levels and whether stabilizing the spine in neutral or lordotic contour with indirect decompression leads to neurological improvement with radiological evidence of anterior decompression. The results of posterior cervical laminectomy and instrumentation with lateral mass screw in terms of radiological and functional outcome in patients with multilevel cervical myelopathy are prospectively evaluated.

MATERIALS AND METHODS

In this prospective study conducted between June 2006 and December 2015, we have evaluated 112 patients with multilevel cervical myelopathy who underwent multilevel cervical laminectomy and instrumentation with lateral mass screw. All patients were evaluated preoperatively and postoperatively with Nurick's grading and Modified Japanese Orthopaedic Association (mJOA) scale for neurological function. Cooper scale and British Medical Research Council grading system for motor function. Curvature index was used to measure the alignment of cervical spine preoperatively and postoperatively. Alignment of the cervical spine was done preoperatively and postoperatively by calculating the curvature index. Axial MRI was used to calculate the severity of compression preoperatively which was calculated as per Singh's criteria and postoperatively to assess the adequacy of decompression at the operated level.

RESULTS

In our study, there were 112 patients including 99 males and 13 females, with mean age of 59.53 years. The mean duration of followup of patients was 33.24 months. In total, cervical laminectomy was performed at 342 levels in 112 patients with an average of 3.05 laminectomies, and in total, 112 lateral mass screws were inserted. On postoperative followup, the mJOA and Nurick's grading showed improvement in all cases as compared to preoperative findings. The mean mJOA improved significantly from 8.56 preoperatively to 13.57 postoperatively (P < 0.001). The mean Nurick's grading also improved significantly from 2.59 preoperatively to 0.66 postoperatively (P < 0.001). The mean Cooper scale also showed significant improvement in both upper and lower limbs postoperatively (P < 0.001). The mean preoperative Cooper scale was 1.75 and postoperative was 0.31 for upper limbs, and the mean Cooper scale was 2.14 preoperatively and 0.56 postoperatively for lower limbs. X-rays done on routine followups showed good alignment of the cervical spine with maintenance of curvature index in all patients. The mean grade of compression as seen on preoperative MRI was 2.46 which reduced significantly postoperatively to 0.16 (P < 0.001).

CONCLUSION

The multilevel cervical laminectomy and instrumentation with lateral mass screw for multilevel cervical myelopathy is a safe technique that provides decompression of the spinal cord, prevents the development of kyphotic spinal deformity and posterior tension band of the spinal cord as associated with laminoplasty or uninstrumented laminectomy.

An Example of Respiratory Dysfunction in Restorative Neurosurgical Procedures

In sleep-related breathing disorders, sleep apnea is a clinical symptom that can be categorized as obstructive sleep apnea (OSA) or mixed apnea by analysis using polysomnography. The occurrence of delayed central sleep apnea (CSA) is an extremely rare complication of cervical laminectomy for spondylotic myelopathy. So far only three studies concerning such an event have been reported in the literature. Naim-ur-Rahman, in 1994, reported a case of postoperative CSA following C3-C6 laminectomy, and Visocchi and colleagues, in 2014, in two studies, stressed the lack of association with any other neurological sign of spinal cord damage. No definitive mechanism has been recognized so far for delayed CSA after cervical laminectomy. A transient dysfunction of the reticulo-spinal fibers directed to the nucleus of the phrenic nerve can be speculated, although neither emi-diaphragm paralysis, nor any prominent nocturnal sleep-related disorders are associated with this delayed CSA.

C5 palsy after cervical laminectomy and fusion: does width of laminectomy matter?

BACKGROUND CONTEXT

A common complication of cervical laminectomy and fusion with instrumentation (CLFI) is development of postoperative C5 nerve palsy. A proposed etiology is excess nerve tension from posterior drift of the spinal cord after decompression. We hypothesize that laminectomy width will be significantly increased in patients with C5 palsy and will correlate with palsy severity.

PURPOSE

The purposes of this study were to evaluate laminectomy width as a risk factor for C5 palsy and to assess correlation with palsy severity.

STUDY DESIGN/SETTING

This is a retrospective, single-institution clinical study.

PATIENT SAMPLE

Patient population included all patients with cervical spondylotic myelopathy who underwent CLFI between 2007 and 2014 by a single surgeon. Patients who underwent CLFI for trauma, infection, or tumor or had previous or circumferential cervical surgery were excluded. All patients with a new C5 palsy received a postoperative magnetic resonance imaging. An additional computed tomography (CT) scan was ordered to assess hardware. All control patients received a CT scan at 6 months postoperatively to evaluate fusion.

OUTCOME MEASURES

The association between width of laminectomy and development of postopeative C5 palsy was measured.

METHODS

Patient comorbidities including obesity, smoking history, and diabetes were recorded in addition to preopertaive and postoperative deltoid and biceps motor strength. Sagittal alignment was measured with C2-C7 Cobb angle preopertaive and postoperative radiographs. The width of laminectomy was measured in a blinded fashion on the postoperative CT scan by two observers.

RESULTS

Seventeen patients with C5 nerve palsy and 12 controls were identified. There were no baseline differences in age, sex, diabetes, smoking history, number of surgical levels, or sagittal alignment. Body mass index was significantly higher in the control cohort. There was no significant increase in the C3-C7 laminectomy width in patients with postoperative C5 palsy. The width of laminectomy measurments were highly similar between the two observers. There was no correlation between laminectomy width and palsy severity.

CONCLUSIONS

This is the largest series of C5 palsies after laminectomy documented with CT imaging. Laminectomy width was not associated with an increased risk of postoperative C5 palsy at any level. Reduction in laminectomy width may not reduce rate of postoperative nerve palsy.

Long-term clinical and radiological follow-up after laminectomy for cervical spondylotic myelopathy

Background:

The role of laminectomy in the surgical treatment of cervical spondylotic myelopathy (CSM) is established even though postoperative cervical sagittal balance changes and a risk for long-term instability have been described. The aim of the present study is to investigate its clinical efficacy and the radiological outcome in the long-term.

Methods:

The authors retrospectively reviewed consecutive cases of patients with CSM, who underwent cervical laminectomy between 1995 and 2010 at the Hospital São João (n = 106). Clinical files were consulted, and the patients reassessed in order to collect information on complaints, previous neurological deficits, surgery and its complications. Subjective and objective clinical evaluation (by three myelopathy scores) and imaging studies were undertaken in order to assess the long-term cervical sagittal curvature and presence of instability.

Results:

After applying exclusion criteria, 57 patients were able to complete the follow-up. A favorable statistically significant difference was obtained when comparing clinical scores. Ninety-one percent of patients were satisfied with the outcome of the surgery. Only 1 patient developed kyphosis according to Ishihara index and none according to the method of Matsumoto. Four patients developed subclinical cervical instability. No clinical-imaging correlation was found.

Conclusions:

If patients are properly selected cervical laminectomy without additional instrumentation is effective in offering a clinical improvement to patients with CSM with a low incidence of clinically significant radiological deterioration.

Post laminoplasty cervical kyphosis-Case report

INTRODUCTION

Cervical kyphosis is a progressive cervical sagittal plane deformity that may cause a reduction in the ability to look horizontally, breathing and swallowing difficulties, sense of thoracic oppression and social isolation. Moreover, cervical kyphosis can cause myelopathy due to a direct compression by osteo-articular structures on the spinal cord or to a transitory ischaemic injury. The treatment of choice is surgery. The goals of surgery are: nervous structures decompression, cervical and global sagittal balance correction and vertebral stabilization and fusion.

PRESENTATION OF CASE

In October 2008 a 35 years old woman underwent surgical removal of a cervical-bulbar ependymoma with C1-C5 laminectomy and a C2-C5 laminoplasty. Five months after surgery, the patient developed a kyphotic posture, with intense neck and scapular girdle pain. The patients had a flexible cervical kyphosis. Therefore, we decided to perform an anterior surgical approach. We performed a corpectomy C4-C5 in order to achieve the anterior decompression; we placed a titanium expansion mesh.

DISCUSSION

Cervical kyphosis can be flexible or fixed. Some authors have reported the use of anterior surgery only for flexible cervical kyphosis as discectomy and corpectomy. This approach is useful for anterior column load sharing however it is not required for deformity correction.

CONCLUSION

The anterior approach is a good surgical option in flexible cervical kyphosis. It is of primary importance the sagittal alignment of the cervical spine in order to decompress the nervous structures and to guarantee a long-term stability.