Ossification of the posterior longitudinal ligament. Results of anterior cervical decompression and arthrodesis in sixty-one North American patients

To infer the probability of cervical ossification of the posterior longitudinal ligament and explore its impact on cervical surgery

The ossification of the posterior longitudinal ligament (OPLL) in the cervical spine is commonly observed in degenerative changes of the cervical spine. Early detection of cervical OPLL and prevention of postoperative complications are of utmost importance. We gathered data from 775 patients who underwent cervical spine surgery at the First Affiliated Hospital of Guangxi Medical University, collecting a total of 84 variables. Among these patients, 144 had cervical OPLL, while 631 did not. They were randomly divided into a training cohort and a validation cohort. Multiple machine learning (ML) methods were employed to screen the variables and ultimately develop a diagnostic model. Subsequently, we compared the postoperative outcomes of patients with positive and negative cervical OPLL. Initially, we compared the advantages and disadvantages of various ML methods. Seven variables, namely Age, Gender, OPLL, AST, UA, BMI, and CHD, exhibited significant differences and were used to construct a diagnostic nomogram model. The area under the curve (AUC) values of this model in the training and validation groups were 0.76 and 0.728, respectively. Our findings revealed that 69.2% of patients who underwent cervical OPLL surgery eventually required elective anterior surgery, in contrast to 86.8% of patients who did not have cervical OPLL. Patients with cervical OPLL had significantly longer operation times and higher postoperative drainage volumes compared to those without cervical OPLL. Interestingly, preoperative cervical OPLL patients demonstrated significant increases in mean UA, age, and BMI. Furthermore, 27.1% of patients with cervical anterior longitudinal ligament ossification (OALL) also exhibited cervical OPLL, whereas this occurrence was only observed in 6.9% of patients without cervical OALL. We developed a diagnostic model for cervical OPLL using the ML method. Our findings indicate that patients with cervical OPLL are more likely to undergo posterior cervical surgery, and they exhibit elevated UA levels, higher BMI, and increased age. The prevalence of cervical anterior longitudinal ligament ossification was also significantly higher among patients with cervical OPLL.

A novel CCDC91 isoform associated with ossification of the posterior longitudinal ligament of the spine works as a non-coding RNA to regulate osteogenic genes

Ossification of the posterior longitudinal ligament of the spine (OPLL) is a common intractable disease that causes spinal stenosis and myelopathy. We have previously conducted genome-wide association studies for OPLL and identified 14 significant loci, but their biological implications remain mostly unclear. Here, we examined the 12p11.22 locus and identified a variant in the 5' UTR of a novel isoform of CCDC91 that was associated with OPLL. Using machine learning prediction models, we determined that higher expression of the novel CCDC91 isoform was associated with the G allele of rs35098487. The risk allele of rs35098487 showed higher affinity in the binding of nuclear proteins and transcription activity. Knockdown and overexpression of the CCDC91 isoform in mesenchymal stem cells and MG-63 cells showed paralleled expression of osteogenic genes, including RUNX2, the master transcription factor of osteogenic differentiation. The CCDC91 isoform directly interacted with MIR890, which bound to RUNX2 and decreased RUNX2 expression. Our findings suggest that the CCDC91 isoform acts as a competitive endogenous RNA by sponging MIR890 to increase RUNX2 expression.

Ossification of the Posterior Longitudinal Ligament: Pathophysiology, Diagnosis, and Management

Ossification of the posterior longitudinal ligament (OPLL) occurs as heterotopic bone forms in the posterior longitudinal ligament, resulting in neural compression, myelopathy, and radiculopathy. OPLL is most commonly observed in East Asian populations, with prevalence rates of 1.9% to 4.3% reported in Japan. OPLL rates are lower in North American and European patients, with reported prevalence of 0.1% to 1.7%. Patients typically develop symptoms due to OPLL in their cervical spines. The etiology of OPLL is multifactorial, including genetic, metabolic, and anatomic factors. Asymptomatic or symptomatic patients with OPLL can be managed nonsurgically, whereas patients with neurologic symptoms may require surgical decompression from an anterior, posterior, or combined approach. Surgical treatment can provide notable improvement in neurologic function. Surgical decision making accounts for multiple factors, including patient comorbidities, neurologic status, disease morphology, radiographic findings, and procedure complication profiles. In this study, we review OPLL epidemiology and pathophysiology, clinical features, radiographic evaluation, management, and complications.

Posterior Decompression and Fusion with Vertical Pressure Procedure in the Treatment of Multilevel Cervical OPLL with Kyphotic Deformity

Objective

To report the outcomes and feasibility of a new technique to change K‐line (−) to K‐line (+) via only a posterior approach to treat multilevel non‐continuous cervical ossification of the posterior longitudinal ligament (C‐OPLL) with kyphotic deformity.

Methods

In this study, 17 consecutive cases of patients who underwent vertical pressure procedure (VP) combined with posterior cervical single‐open‐door laminoplasty and instrumented fusion from January 1, 2017 to December 31, 2019 were enrolled. The following radiographic parameters: C2‐C7 Cobb angle, local Cobb angle, extent of OPLL, and the distance from OPLL to the K‐line(DK) were measured and analyzed. Clinically, the JOA score, VAS‐N and VAS‐A, NDI, and complications were collected from medical records to evaluate the clinical outcomes.

Results

All 17 cases shifted from K‐line (−) to K‐line (+).Comparing the preoperative images to the final follow‐up images, the mean C2‐7 Cobb angle changed from −6.94° ± 8.30° to 8.18° ± 4.43°, and the local Cobb angle altered from −9.12° ± 8.68° to 6.65° ± 6.11°. The mean DK increased from −2.64 ± 1.52 mm to 3.09 ± 2.19 mm. One patient showed C5 palsy and recovered within 3 months. The mean JOA score increased from 8.88 ± 2.11 to 14.71 ± 1.36. The average NDI decreased from 20.65 ± 7.80 to 8.94 ± 4.93. The mean VAS‐N and VAS‐A decreased from 3.44 ± 1.80 and 4.69 ± 1.97 to 1.25 ± 0.86 and 1.38 ± 1.16. All patients were followed up for at least 1 year.

Conclusion

A new technique added to posterior decompression and fusion (PDF), the vertical pressure procedure effectively corrects K‐line (−) to K‐line (+) and avoids the shortcomings of conventional anterior decompression and fusion (ADF) as well as PDF to provide a relatively safe and adequate decompression, cervical realignment. It pronounced satisfactory clinical outcome for extensive non‐continuous OPLL with kyphotic deformity even though OPLL remains ventral to the spinal cord.

A deep learning algorithm to identify cervical ossification of posterior longitudinal ligaments on radiography

The cervical ossification of the posterior longitudinal ligament (cOPLL) is sometimes misdiagnosed or overlooked on radiography. Thus, this study aimed to validate the diagnostic yield of our deep learning algorithm which diagnose the presence/absence of cOPLL on cervical radiography and highlighted areas of ossification in positive cases and compare its diagnostic accuracy with that of experienced spine physicians. Firstly, the radiographic data of 486 patients (243 patients with cOPLL and 243 age and sex matched controls) who received cervical radiography and a computer tomography were used to create the deep learning algorithm. The diagnostic accuracy of our algorithm was 0.88 (area under curve, 0.94). Secondly, the numbers of correct diagnoses were compared between the algorithm and consensus of four spine physicians using 50 independent samples. The algorithm had significantly more correct diagnoses than spine physicians (47/50 versus 39/50, respectively; p = 0.041). In conclusion, the accuracy of our deep learning algorithm for cOPLL diagnosis was significantly higher than that of experienced spine physicians. We believe our algorithm, which uses different diagnostic criteria than humans, can significantly improve the diagnostic accuracy of cOPLL when radiography is used.

METTL3 Regulates Ossification of the Posterior Longitudinal Ligament via the lncRNA XIST/miR-302a-3p/USP8 Axis

The prevalence of ossification of the posterior longitudinal ligament (OPLL) is increasing, and currently there is no effective medical treatment for OPLL. Methyltransferase like 3 (METTL3), one of the components of the N⁶-methyladenosine (m⁶A) methyltransferase complex, regulates gene expression via modification of mRNA. Although METTL3 has been implicated in a variety of diseases, its role in OPLL remains to be elucidated. Primary ligament fibroblasts were used in this study. To investigate the role of METTL3 in OPLL, METTL3 was silenced or overexpressed. m⁶A RNA methylation was measured by commercially available kits. Luciferase reporter assay was performed to investigate the binding of miR-302a-3p and METTL3, and the binding of miR-302a-3p and USP8. Quantitative RT-PCR and western blots were used to evaluate mRNA and protein expression, respectively. OPLL increases METTL3 and its m⁶A modification. Overexpressing METTL3 significantly promoted osteogenic differentiation of primary ligament fibroblasts. Mechanism study showed that METTL3 increased m⁶A methylation of long non-coding RNA (lncRNA) X-inactive specific transcript (XIST). Further study showed that lncRNA XIST regulates osteogenic differentiation of primary ligament fibroblasts via miR-302a-3p, which targets ubiquitin-specific protease 8 (USP8). METTL3 enhanced osteogenic differentiation of primary ligament fibroblasts via the lncRNA XIST/miR-302a-3p/USP8 axis. The findings highlight the importance of METTL3-mediated m⁶A methylation of XIST in OPLL and provide new insights into therapeutic strategies for OPLL.

Vertebral Body Sliding Osteotomy for Cervical Myelopathy With Rigid Kyphosis

Cervical spondylotic myelopathy is surgically demanding when associated with rigid kyphosis. Posterior surgery cannot restore cervical lordosis, and adequate decompression is not possible with rigid kyphosis. Vertebral body sliding osteotomy (VBSO) is a safe and novel technique for anterior decompression in patients with multilevel cervical spondylotic myelopathy. It is safe in terms of dural tear, pseudarthrosis, and graft dislodgement, which are demonstrated at high rates in anterior cervical corpectomy and fusion. In addition, VBSO is a powerful method for restoring cervical lordosis through multilevel anterior cervical discectomy and fusion above and below the osteotomy level. It may be a feasible treatment option for patients with cervical spondylotic myelopathy and kyphotic deformity. This is a technical note and literature review that describes the procedures involved in VBSO.

Improvement in cervical lordosis and sagittal alignment after vertebral body sliding osteotomy in patients with cervical spondylotic myelopathy and kyphosis

OBJECTIVE

Vertebral body sliding osteotomy (VBSO) is a safe, novel technique for anterior decompression in patients with multilevel cervical spondylotic myelopathy. Another advantage of VBSO may be the restoration of cervical lordosis through multilevel anterior cervical discectomy and fusion (ACDF) above and below the osteotomy level. This study aimed to evaluate the improvement and maintenance of cervical lordosis and sagittal alignment after VBSO.

METHODS

A total of 65 patients were included; 34 patients had undergone VBSO, and 31 had undergone anterior cervical corpectomy and fusion (ACCF). Preoperative, postoperative, and final follow-up radiographs were used to evaluate the improvements in cervical lordosis and sagittal alignment after VBSO. C0-2 lordosis, C2-7 lordosis, segmental lordosis, C2-7 sagittal vertical axis (SVA), T1 slope, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and Japanese Orthopaedic Association scores were measured. Subgroup analysis was performed between 15 patients with 1-level VBSO and 19 patients with 2-level VBSO. Patients with 1-level VBSO were compared to patients who had undergone 1-level ACCF.

RESULTS

C0-2 lordosis (41.3° ± 7.1°), C2-7 lordosis (7.1° ± 12.8°), segmental lordosis (3.1° ± 9.2°), and C2-7 SVA (21.5 ± 11.7 mm) showed significant improvements at the final follow-up (39.3° ± 7.2°, 13° ± 9.9°, 15.2° ± 8.5°, and 18.4 ± 7.9 mm, respectively) after VBSO (p = 0.049, p < 0.001, p < 0.001, and p = 0.038, respectively). The postoperative segmental lordosis was significantly larger in 2-level VBSO (18.8° ± 11.6°) than 1-level VBSO (10.3° ± 5.5°, p = 0.014). The final segmental lordosis was larger in the 1-level VBSO (12.5° ± 6.2°) than the 1-level ACCF (7.2° ± 7.6°, p = 0.023). Segmental lordosis increased postoperatively (p < 0.001) and was maintained until the final follow-up (p = 0.062) after VBSO. However, the postoperatively improved segmental lordosis (p < 0.001) decreased at the final follow-up (p = 0.045) after ACCF.

CONCLUSIONS

Not only C2-7 lordosis and segmental lordosis, but also C0-2 lordosis and C2-7 SVA improved at the final follow-up after VBSO. VBSO improves segmental cervical lordosis markedly through multiple ACDFs above and below the VBSO level, and a preserved vertebral body may provide more structural support.

A Systematic Review of Classification Systems for Cervical Ossification of the Posterior Longitudinal Ligament

DESIGN

Systematic review.

OBJECTIVE

To conduct a systematic review to (1) summarize various classification systems used to describe cervical ossification of the posterior longitudinal ligament (OPLL) and (2) evaluate the diagnostic accuracy of various imaging modalities and the reliability of these classification systems.

METHODS

A search was performed to identify studies that used a classification system to categorize patients with OPLL. Furthermore, studies were included if they reported the diagnostic accuracy of various imaging modalities or the reliability of a classification system.

RESULTS

A total of 167 studies were deemed relevant. Five classification systems were developed based on X-ray: the 9-classification system (0.60%); continuous, segmental, mixed, localized or focal, circumscribed and others (92.81%); hook, staple, bridge, and total types (2.40%); distribution of OPLL (2.40%); and K-line classification (4.19%). Six methods were based on computed tomography scans: free-type, contiguous-type, and broken sign (0.60%); hill-, plateau-, square-, mushroom-, irregular-, or round-shaped (5.99%); rectangular, oval, triangular, or pedunculate (1.20%); centralized or laterally deviated (1.80%); plank-, spindle-, or rod-shaped (0.60%); and rule of nine (0.60%). Classification systems based on 3-dimensional computed tomography were bridging and nonbridging (1.20%) and flat, irregular, and localized (0.60%). A single classification system was based on magnetic resonance imaging: triangular, teardrop, or boomerang. Finally, a variation of methods was used to classify OPLL associated with the dura mater (4.19%).

CONCLUSIONS

The most common method of classification was that proposed by the Japanese Ministry of Health, Labour and Welfare. Other important methods include K-line (+/-), signs of dural ossification, and patterns of distribution.

Ossification of the posterior longitudinal ligament in the cervical spine: a review

Ossification of the posterior longitudinal ligament (OPLL) is a rare pathologic process of lamellar bone deposition that can result in spinal cord compression. While multiple genetic and environmental factors have been related to the development of OPLL, the pathophysiology remains poorly understood. Asymptomatic patients may be managed conservatively and patients with radiculopathy or myelopathy should be considered for surgical decompression. Multiple studies have demonstrated the morphology and size of the OPLL as well as the cervical alignment have significant implications for the appropriate surgical approach and technique. In this review, we aim to address all the available literature on the etiology, history, presentation, and management of OPLL in an effort to better understand OPLL and give our recommendations for the treatment of patients presenting with OPLL.

A novel anterior decompression technique (vertebral body sliding osteotomy) for ossification of posterior longitudinal ligament of the cervical spine

BACKGROUND CONTEXT

Conventional anterior decompression surgery for cervical myelopathy, including anterior corpectomy and fusion, is technically demanding and is known to be associated with a higher incidence of surgery-related complications, including cerebrospinal fluid (CSF) leakage, neurologic deterioration, and graft failure compared with posterior surgery.

PURPOSE

We introduce a novel anterior decompression technique (vertebral body sliding osteotomy [VBSO]) for cervical myelopathy caused by ossification of posterior longitudinal ligament (OPLL) and evaluate the efficacy and safety of this procedure.

STUDY DESIGN

This is a case series for novel surgical technique.

PATIENT SAMPLE

Fourteen patients (M:F=11:3, mean age 56.9±10) with cervical myelopathy caused by OPLL who underwent VBSO by a single surgeon were included.

OUTCOME MEASURES

The surgical outcome was evaluated according to the Japanese Orthopaedic Association score for cervical myelopathy (C-JOA score), and the recovery rate of the C-JOA score was calculated. Patients were also evaluated radiographically with plain and dynamic cervical spine radiographs and pre- and postoperative computed tomography images.

METHODS

Fourteen patients were followed up for more than 24 months, and operation time, estimated blood loss, neurologic outcomes, and surgery-related complications were investigated. Radiological measurements were also performed to analyze the following parameters: (1) canal-occupying ratio and postoperative canal widening, and (2) pre- and postoperative sagittal alignment.

RESULTS

The mean recovery rate of C-JOA score at the final follow-up was 68.65±17.8%. There were no perioperative complications, including neurologic deterioration, vertebral artery injury, esophageal injury, graft dislodgement, and CSF leaks, after surgery except for pseudarthrosis in one case. An average spinal canal compromised ratio by OPLL decreased from 61.5±8.1% preoperatively to 16.5±11.2% postoperatively. An average postoperative canal widening was 5.15±1.39 mm, and improvement of cervical alignment was observed in all patients, with average recovery angle of 7.3±6.1° postoperatively.

CONCLUSIONS

The VBSO allows sufficient decompression of spinal cord and provides excellent neurologic outcomes. Because surgeons do not need to manipulate the OPLL mass directly, this technique could significantly decrease surgery-related complications. Furthermore, as VBSO is based on the multilevel discectomy and fusion technique, it would be more helpful to restore a physiological lordosis.

Ossification of the Posterior Longitudinal Ligament in Cervical Spine: Prevalence, Management, and Prognosis

Ossification of the posterior longitudinal ligament (OPLL) in the cervical spine and related neurological complications are not uncommon in East Asian countries. The estimated prevalence of cervical OPLL-related hospitalization is 7.7 per 100,000 person-years in Taiwan, and higher incidence rates have been observed in elderly and male patients. Although cervical OPLL is frequently insidious, it can eventually cause myelopathy and predispose patients to spinal cord injury (SCI). There are multiple options for managing cervical OPLL, ranging from observation to many kinds of surgical procedures, including posterior laminoplasty, laminectomy with or without fusion, anterior corpectomy with or without instrumentation, and circumferential decompression and fusion. None of these surgical approaches is free of complications. However, to date, there is still a lack of consensus regarding the choice of the surgical approach and the timing of surgical intervention. Cervical SCI and related neurological disabilities are more likely to occur in OPLL patients, who should therefore be cautioned regarding the possibility of a subsequent SCI if treated without surgery. This article aimed to review the prevalence, management strategies, and prognosis of cervical OPLL.

Is atlantoaxial instability the cause of "high" cervical ossified posterior longitudinal ligament? Analysis on the basis of surgical treatment of seven patients

BACKGROUND

Multilevel ossified posterior longitudinal ligaments (OPLLs), particularly those that extend into the high cervical region, are formidable and challenging surgical problems. The aim of the presentation is to analyze the results of surgical treatment of seven consecutive patients having high cervical OPLL with atlantoaxial and subaxial facetal fixations.

OBJECTIVES

We analyze the role of atlantoaxial instability in the management of OPLL that extended into the high cervical region, above the lower border of C3 vertebra.

MATERIALS AND METHODS

All patients in the series were males. The age of the patients ranged 48-65 years. Clinical evaluation was done by a 5-point clinical grading scale described by us, Japanese Orthopedic Association (JOA) score, and visual analog scale (VAS). All patients were identified to have relatively "subtle" but definite atlantoaxial facetal instability on sagittal imaging and the instability was confirmed by direct handling of the facets during surgery. All patients were treated by multilevel facetal fixation that included fixation of atlantoaxial facets. The aim of surgery was stabilization and arthrodesis of the involved spinal segments, as instability was considered to be the prime pathogenetic factor of OPLL. Spinal canal decompression, either by anterior corpectomy or discoidectomy or by posterior laminectomy or laminoplasty was not done and no attempts were made to remove the OPLL. At an average follow-up of 8 months, all patients showed progressive symptomatic recovery.

CONCLUSION

Atlantoaxial facetal instability can be a cause or an association of high cervical OPLL. Stabilization of the atlantoaxial joint forms a remarkably effective method of treatment.

Value of intraoperative neurophysiological monitoring to reduce neurological complications in patients undergoing anterior cervical spine procedures for cervical spondylotic myelopathy

The primary aim of this study was to conduct a systematic review of reports of patients with cervical spondylotic myelopathy and to assess the value of intraoperative monitoring (IOM), including somatosensory evoked potentials, transcranial motor evoked potentials and electromyography, in anterior cervical procedures. A search was conducted to collect a small database of relevant papers using key words describing disorders and procedures of interest. The database was then shortlisted using selection criteria and data was extracted to identify complications as a result of anterior cervical procedures for cervical spondylotic myelopathy and outcome analysis on a continuous scale. In the 22 studies that matched the screening criteria, only two involved the use of IOM. The average sample size was 173 patients. In procedures done without IOM a mean change in Japanese Orthopaedic Association score of 3.94 points and Nurick score by 1.20 points (both less severe post-operatively) was observed. Within our sub-group analysis, worsening myelopathy and/or quadriplegia was seen in 2.71% of patients for studies without IOM and 0.91% of patients for studies with IOM. Variations persist in the existing literature in the evaluation of complications associated with anterior cervical spinal procedures. Based on the review of published studies, sufficient evidence does not exist to make recommendations regarding the use of different IOM modalities to reduce neurological complications during anterior cervical procedures. However, future studies with objective measures of neurological deficits using a specific IOM modality may establish it as an effective and reliable indicator of injury during such surgeries.

Screw Back-Out Following "Open-Door" Cervical Laminoplasty: A Review of 165 Plates

STUDY DESIGN

Retrospective study.

PURPOSE

To investigate safety profile of open door laminoplasty plates.

OVERVIEW OF LITERATURE

Few reports have documented potential complications related to the use of cervical laminoplasty plates.

METHODS

Records and radiographs of consecutive plated laminoplasty patients of one academic surgeon were analyzed. Group 1 had screw back-out, defined as change in screw position, and group 2 did not.

RESULTS

Forty-two patients (mean age, 56.9) underwent "open-door" cervical laminoplasty using 165 plates. Mean follow-up was 24 months (range, 12-49 months). Mean Nurick grade improved from 2.1 to 0.9 postoperatively. Cervical lordosis (C2-7) was 12.1° preoperatively and 10.0° postoperatively. Range-of-motion was 27.0° preoperatively and 23.4° postoperatively. Partial screw back-out was noted in 27 of 165 plates (16.4%) and in 34 of 660 screws (5.2%). Of the 34 screws, 27 (79.4%) were at either the most cranial (12/27, 44.4%) or the most caudal (15/27, 55.5%) level. Cranially, 11/12 screws (91.7%) had back-out. Caudally, 9/15 lateral mass screws (60.0%) backed-out versus 6 laminar screws (40.0%). Of the 22 patients with screw back-out, 15 (68.2%) occurred <3 months postoperative and 6 (27.3%) occurred 4-12 months postoperative. No statistical differences were found between group 1 and 2 for age, gender, preoperative and postoperative lordosis, focal sagittal alignment, range-of-motion, or Nurick grade. Despite screw backout in 22 patients, there were no plate dislodgements, laminoplasty closure, or neurological deterioration.

CONCLUSIONS

Although screw back-out may occur with the use of cervical laminoplasty plates, the use of these plates without a bone block appears to be safe and reliable. As screw back-out is most common at the cranial and caudal ends of the laminoplasty, we recommend using the maximum number of screws (typically 2 for the lateral mass and 2 for the spinous process) at these levels to secure the plate to the bone.

A new method to determine whether ossified posterior longitudinal ligament can be resected completely and safely: spinal canal "Rule of Nine" on axial computed tomography

PURPOSE

To introduce the new method of spinal canal "Rule of Nine" on axial computed tomography (CT) to determine whether ossified posterior longitudinal ligament (OPLL) can be resected completely and safely.

METHODS

From January 2008 to January 2013, we retrospectively analyzed 308 patients with cervical OPLL who underwent anterior corpectomy. Patients were examined by cervical plain X-ray, CT, and magnetic resonance imaging. The characteristics of OPLL on axial CT, dural mater adhesion and ossification, complete resection of the ossified mass, cerebrospinal fluid (CSF) leakage, spinal cord injury (SCI), and postoperative outcome were all studied. OPLL was characterized at the maximum ossified level using spinal canal "Rule of Nine" on axial CT.

RESULTS

OPLL was completely and safely resected in 129 patients, whose ossified mass was within the safety zone. No CSF leakage or SCI occurred. The most ossified material was resected when OPLL was within the danger zone in 21 patients. There were two cases of SCI and seven of CSF leakage. In the other 158 patients, the ossified mass was within the intermediate zone. In 96 patients the width of the ossified mass was <2 resection units. It was completely resected and one case had CSF leakage. In the other 62 cases, the ossified mass was >2 resection units and there were nine cases of CSF leakage. CSF leakage and SCI increased significantly when the ossified mass was ≥6 units. The inter- and intraobserver κ values were 0.76 and 0.84, respectively, showing a good reliability.

CONCLUSIONS

Our new method can be used to determine whether OPLL can be resected completely and safely, and identify potential risks and complications.

Surgical treatment for ossification of the posterior longitudinal ligament in the cervical spine

Although classically associated with patients of East Asian origin, ossification of the posterior longitudinal ligament (OPLL) may cause myelopathy in patients of any ethnic origin. Degeneration of the PLL is followed by endochondral ossification, resulting in spinal cord compression. Specific genetic polymorphisms and medical comorbidities have been implicated in the development of OPLL. Patients should be evaluated with a full history and neurologic examination, along with cervical radiographs. Advanced imaging with CT and MRI allows three-dimensional evaluation of OPLL. Minimally symptomatic patients can be treated nonsurgically, but patients with myelopathy or severe stenosis are best treated with surgical decompression. OPLL can be treated via an anterior (ie, corpectomy and fusion) or posterior (ie, laminectomy and fusion or laminoplasty) approach, or both. The optimal approach is dictated by the classification and extent of OPLL, cervical spine sagittal alignment, severity of stenosis, and history of previous surgery. Anterior surgery is associated with superior outcomes when OPLL occupies >50% to 60% of the canal, despite increased technical difficulty and higher complication rates. Posterior surgery is technically easier and allows decompression of the entire cervical spine, but patients may experience late deterioration because of disease progression.

Clinical efficacy of semi-laminectomy and posterior stabilization for treatment of thoracolumbar burst fracture

OBJECTIVE

The purpose of the present study was to investigate the efficacy of posterior semi-laminectomy, restoration of bony fragments and short-segment pedicle screw fixation for treatment of thoracolumbar burst fractures.

METHODS

From January 2008 to April 2011, 21 patients (19 males and 2 females) who suffered single-level thoracolumbar burst fractures were enrolled in this study. Fractures at T11, T12, L1, L2 and L3 level occurred in 3, 5, 8, 4 cases and 1 case, respectively. The patients enrolled were presented with 30%-50% encroachment of spinal canal, partial neurological function deficits and intact pedicles, and underwent semi-laminectomy on the fractured thoracolumbar spine, restoration of the fractured bony fragments with special bone punch beneath dural sac, as well as pedicle screw fixation of the fractured thoracolumbar spine and the two vertical neighboring segments.

RESULTS

All patients were followed up for 12-48 months, with a mean of 17 months. The mean kyphotic deformity was reduced from (17.3 ± 5.3)° preoperatively to (9.2 ± 4.1)° at follow-up within 12 months. The mean spinal canal diameter increased from (9.7 ± 2.7) mm before surgery to (13.3 ± 1.4) mm at follow-up. Neurological improvement occurred in all subjects after average 2.5 months (range, 1-7 months). Only postoperative wound dehiscence was observed in 1 case, which was caused by implant reaction of calcium phosphate and healed after debridement.

CONCLUSION

Semi-laminectomy and restoration of bony fragments is a safe and effective therapeutic measure for thoracolumbar burst fractures with spinal canal encroachment of less than 50%.

Cervical curvature, spinal cord MRIT2 signal, and occupying ratio impact surgical approach selection in patients with ossification of the posterior longitudinal ligament

OBJECTIVE

Factors impacting surgical options and outcomes in patients with cervical ossification of the posterior longitudinal ligament (OPLL) were explored.

METHODS

A retrospective analysis was conducted of 127 eligible cervical OPLL patients (61 males, 66 females) aged 41-70 years (mean 55.2 years) selected from 152 total OPLL patients treated from 2002 to 2006, with 5-10-year (mean 6.8 years) follow-up. Patients underwent anterior subtotal corpectomy with ossification ligament resection (anterior surgery, n = 68) or posterior cervical double-door laminoplasty (posterior surgery, n = 59). Radiographic assessments of cervical curvature, T2-weighted MRI (MRIT2) signal, and OPLL occupying ratio were correlated with surgical strategy before surgery and at 1, 5 weeks, and 5 years.

RESULTS

Lordosis increased following anterior surgery, though kyphosis improved by 10.3 %. The canal stenosis occupying ratio was >50 %, and short-term improvement following anterior surgery was significantly higher than posterior surgery (P > 0.0001). Superior neurological function was observed in patients with unchanged versus high spinal MRIT2 signals (P = 0.0434). No significant differences were observed in short-term outcomes between anterior and posterior surgeries in high spinal MRIT2 signal patients, but anterior surgery produced significantly better long-term outcomes at 1 week (P = 0.7564) and 1 year (P = 0.0071). Complications occurred in five anterior and three posterior surgeries.

CONCLUSION

Preoperative assessment of cervical curvature, MRIT2 signal, and occupying ratio can be used to guide clinical surgical approach selection to potentially produce better long-term outcomes in patients with OPLL.

Incidental durotomy after spinal surgery: a prospective study in an academic institution

Object

Incidental durotomies (IDs) are an unfortunate but anticipated potential complication of spinal surgery. The authors surveyed the frequency of IDs for a single spine surgeon and analyzed the major risk factors as well as the impact on long-term patient outcomes.

Methods

The authors conducted a prospective review of elective spinal surgeries performed over a 15-year period. Any surgery involving peripheral nerve only, intradural procedures, or dural tears due to trauma were excluded from analysis. The incidence of ID was categorized by surgery type including primary surgery, revision surgery, and so forth. Incidence of ID was also examined in the context of years of physician experience and training. Furthermore, the incidence and types of sequelae were examined in patients with an ID.

Results

Among 3000 elective spinal surgery cases, 3.5% (104) had an ID. The incidence of ID during minimally invasive procedures (3.3%) was similar, but no patients experienced long-term sequelae. The incidence of ID during revision surgery (6.5%) was higher. There was a marked difference in incidence between cervical (1.3%) and thoracolumbar (5.1%) cases. The incidence was lower for cases involving instrumentation (2.4%). When physician training was examined, residents were responsible for 49% of all IDs, whereas fellows were responsible for 26% and the attending for 25%. Among all of the cases that involved an ID, 7.7% of patients went on to experience a neurological deficit as compared with 1.5% of those without an ID. The overall failure rate of dural repair was 6.9%, and failure was almost 3 times higher (13%) in revision surgery as compared with a primary procedure (5%).

Conclusions

The authors established a reliable baseline incidence for durotomy after spine surgery: 3.5%. They also identified risk factors that can increase the likelihood of a durotomy, including location of the spinal procedure, type of procedure performed, and the implementation of a new procedure. The years of physician training or resident experience did not appear to be a major risk for ID.

Ossification of the posterior longitudinal ligament: pathogenesis, management, and current surgical approaches. A review

Ossification of the posterior longitudinal ligament (OPLL) is an important cause of cervical myelopathy that results from bony ossification of the cervical or thoracic posterior longitudinal ligament (PLL). It has been estimated that nearly 25% of patients with cervical myelopathy will have features of OPLL. Patients commonly present in their mid-40s or 50s with clinical evidence of myelopathy. On MR and CT imaging, this can be seen as areas of ossification that commonly coalesce behind the cervical vertebral bodies, leading to direct ventral compression of the cord. While MR imaging will commonly demonstrate associated changes in the soft tissue, CT scanning will better define areas of ossification. This can also provide the clinician with evidence of possible dural ossification. The surgical management of OPLL remains a challenge to spine surgeons. Surgical alternatives include anterior, posterior, or circumferential decompression and/or stabilization. Anterior cervical stabilization options include cervical corpectomy or multilevel anterior cervical corpectomy and fusion, while posterior stabilization approaches include instrumented or noninstrumented fusion or laminoplasty. Each of these approaches has distinct advantages and disadvantages. While anterior approaches may provide more direct decompression and best improve myelopathy scores, there is soft-tissue morbidity associated with the anterior approach. Posterior approaches, including laminectomy and fusion and laminoplasty, may be well tolerated in older patients. However, there often is associated axial neck pain and less improvement in myelopathy scores. In this review, the authors discuss the epidemiology, imaging findings, and clinical presentation of OPLL. The authors additionally discuss the merits of the different surgical techniques in the management of this challenging disease.

An aid to the explanation of surgical risks and complications: the International Spinal Surgery Information Sheet

STUDY DESIGN

Presentation and analysis of a patient information sheet.

OBJECTIVE

To produce an evidence-based information sheet that will serve as an aide-memoire to the process of taking informed consent prior to spinal surgery.

SUMMARY OF BACKGROUND DATA

Consent for a surgical intervention is the end of a process of discussion between the surgeon and the patient. It is essential that the patient has been provided with sufficient information to make an informed judgment as to whether the benefits of a proposed procedure will outweigh its risks.

METHODS

We searched MEDLINE, the Cochrane database of systematic reviews and personal libraries for articles reporting complications of the surgical treatment of spinal diseases with particular reference to the most commonly treated conditions. A draft document was drawn up referencing the odds of specific complications. This was circulated to the National Health Service Scotland Central Legal Office for scrutiny and to an English language expert at the University of Edinburgh for translation to lay English. Finally, the document was issued to 50 patients in the outpatient clinic and scored on visual analog scales (VAS) for the ease of understanding, usefulness, and length.

RESULTS

The product of this project was a two-page A4 sheet, with the front page outlining information applicable to spinal surgery "in general" and a back page detailing all common risks, relating to a headline procedure, that a Court of Law would expect a surgeon to discuss. The patients' VAS score (0-10) for "ease of understanding" was 8.8 ± 1.3 and for "usefulness" 8.9 ± 1.0 (means ± SD). Forty-three of 50 patients (86%) indicated that the length of the document was "just right" and seven (14%) of them that it was "too long."

CONCLUSION

The ISSiS is user friendly and can be employed as a tool in the process of obtaining consent.

Conservatively treated ossification of the posterior longitudinal ligament increases the risk of spinal cord injury: a nationwide cohort study

The optimal treatment strategy for ossification of the posterior longitudinal ligament (OPLL) depends on symptoms and is uncertain. Whether the risk of spinal cord injury (SCI) is increased in patients with cervical spinal stenosis or myelopathy caused by OPLL remains unclear. This study aimed to evaluate the risk of SCI in patients with OPLL of the cervical spine when managed with conservative treatment (no surgery). Study subjects were identified from a nationwide cohort of 26,544,883 people from 1998 to 2005 and were divided into the OPLL group (n=265), who were hospitalized for OPLL but had conservative treatment (no surgery), and the comparison group (n=5339), composed of age- and sex-matched people. Until the end of 2008, a total of 5604 subjects were followed-up for 34,723.5 person-years. The propensity score method was used to adjust for covariates. Kaplan-Meier and Cox regression analyses were performed. The incidence rate of cervical SCI in the OPLL group was found to be significantly higher than in the comparison group (4.81 versus 0.18 per 1000 person-years; p<0.001). Cervical SCI was more likely to happen in the OPLL group than in the comparison group (crude hazard ratio [HR] 25.64; p<0.001). After adjustments, the OPLL group had a 32.16-fold (p<0.001) higher risk for cervical SCI. Disability caused by SCI had an even higher risk (HR=110.72, adjusted HR=104.78; p<0.001) for the OPLL group. Therefore, cervical SCI and related disabilities are more likely to happen in OPLL patients, who should be cautioned for subsequent SCI if treated conservatively.

A systematic review of complications in cervical spine surgery for ossification of the posterior longitudinal ligament

BACKGROUND CONTEXT

Surgical management of ossification of the posterior longitudinal ligament (OPLL) is associated with complications. However, surgical complications for OPLL have not been clearly documented.

PURPOSE

To review and summarize the incidence of surgical complications of OPLL in the cervical spine and evaluate the impact of surgical approach (anterior or posterior), year of study publication, follow-up duration, and the surgical outcome on complication incidence.

STUDY DESIGN

Systematic review.

METHODS

An English literature review was conducted especially on surgical complications of cervical OPLL. The incidence of complications was statistically summarized, with its correlation to surgical approaches, year of study publications, follow-up duration, and the surgical outcome was statistically evaluated.

RESULTS

Twenty-seven retrospective studies, including a total of 1,558 patients, were reviewed. The overall incidence of surgical complications of cervical OPLL was 21.8%. Neurologic deficit (8.3%, overall rate), cerebrospinal fluid leakage (CFL) (5.1%), axial pain (3.5%), and implant complications (3.5%) were relatively common. The incidence of complications for posterior approach was not statistically different from those for anterior procedures. However, with regard to individual complication, C5 palsy and axial pain occurred more frequently in patients approached posteriorly, whereas CFL, implant complications, hoarseness, dysphagia, and dyspnea appeared more common in anterior cases.

CONCLUSIONS

There is a relatively high incidence of surgical complications for cervical OPLL compared with other cervical degeneration diseases. It is, therefore, necessary for surgeons to take into consideration the risk of surgical complications when communicating with patients for decision making and to alert complications during or after surgical procedures.

Anterior surgery in selective patients with massive ossification of posterior longitudinal ligament of cervical spine: technical note

STUDY DESIGN

The study includes case series, technical note and review of literature.

OBJECTIVE

The objective of this study was to assess the validity of the radiographic indicator and the result of anterior operation for massive ossification of posterior longitudinal ligament (MOPLL, ossification of posterior longitudinal ligament with an occupying ratio exceeding 50%). Anterior decompression yielded a better outcome than posterior approach in patients with MOPLL of cervical spine. But anterior surgery has the problem of technically demanding and was associated with a high incidence of surgery-related complications. Many ways for reducing the risk of anterior surgery have been reported, including floating method, employing microscopes or burrs, and laser-assisted corpectomy.

MATERIALS AND METHODS

A case series of selective patients with MOPLL of cervical spine undergoing anterior surgery is reported. All patients were strictly selected based on CT images with the appearance of open-base. 29 cases with more than 12 months follow-up (average, 31.0 ± 10.0 m) were reviewed. Average age at operation was 59.3 ± 8.2 years (43-73 years). Anterior decompression was done only for one or two vertebrae.

RESULTS

One corpectomy was done in 13 cases, two corpectomies in 3 cases, and one corpectomy and one discectomy in 13 cases. Three levels were fused in 16 cases and two levels in 13 cases. No permanent neurological deterioration was observed. Neurological improvement was observed in every patients with an average improvement rate of 64 ± 23%. Mesh migration was observed in one case. A fusion rate of 100% was achieved.

CONCLUSION

Anterior surgery using our technique may be a relatively simple and safe procedure in selective patients with massive ossification of posterior longitudinal ligament of cervical spine.

Approach-related complications after decompression for cervical ossification of the posterior longitudinal ligament

The surgical management of compressive cervical ossification of the posterior longitudinal ligament (OPLL) can be challenging. Traditionally, approach indications for decompression of cervical spondylotic myelopathy have been used. However, the postoperative complication profile after cervical OPLL decompression is unique and may require an alternative approach paradigm. The authors review the literature on approach-related OPLL complications and suggest a management strategy for patients with single- or multiple-segment OPLL with or without greater than 50% canal stenosis.

Laminoplasty outcomes: is there a difference between patients with degenerative stenosis and those with ossification of the posterior longitudinal ligament?

Object

Two common causes of cervical myelopathy include degenerative stenosis and ossification of the posterior longitudinal ligament (OPLL). It has been postulated that patients with OPLL have more complications and worse outcomes than those with degenerative stenosis. The authors sought to compare the surgical results of laminoplasty in the treatment of cervical stenosis with myelopathy due to either degenerative changes or segmental OPLL.

Methods

The authors conducted a retrospective review of 40 instrumented laminoplasty cases performed at a single institution over a 4-year period to treat cervical myelopathy without kyphosis. Twelve of these patients had degenerative cervical stenotic myelopathy ([CSM]; degenerative group), and the remaining 28 had segmental OPLL (OPLL group). The 2 groups had statistically similar demographic characteristics and number of treated levels (mean 3.9 surgically treated levels; p > 0.05). The authors collected perioperative and follow-up data, including radiographic results.

Results

The overall clinical follow-up rate was 88%, and the mean clinical follow-up duration was 16.4 months. The mean radiographic follow-up rate was 83%, and the mean length of radiographic follow-up was 9.3 months. There were no significant differences in the estimated blood loss (EBL) or length of hospital stay (LOS) between the groups (p > 0.05). The mean EBL and LOS for the degenerative group were 206 ml and 3.7 days, respectively. The mean EBL and LOS for the OPLL group were 155 ml and 4 days, respectively. There was a statistically significant improvement of more than one grade in the Nurick score for both groups following surgery (p < 0.05). The Nurick score improvement was not statistically different between the groups (p > 0.05). The visual analog scale (VAS) neck pain scores were similar between groups pre- and postoperatively (p > 0.05). The complication rates were not statistically different between groups either (p > 0.05). Radiographically, both groups lost extension range of motion (ROM) following laminoplasty, but this change was not statistically significant (p > 0.05).

Conclusions

Patients with CSM due to either degenerative disease or segmental OPLL have similar perioperative results and neurological outcomes with laminoplasty. The VAS neck pain scores did not improve significantly with laminoplasty for either group. Laminoplasty may limit extension ROM.

Management of cerebrospinal fluid leaks after anterior decompression for ossification of the posterior longitudinal ligament: a review of the literature

Object

Anterior decompression is an effective way to treat cervical myelopathy associated with ossification of the posterior longitudinal ligament (OPLL); however, this approach is associated with an increased risk of a dural tear and resultant CSF leak because fusion of the dura with the ossified PLL is common in these cases. The authors review the literature and present an algorithm for treatment of CSF leaks in these patients.

Methods

A MEDLINE review was performed to identify papers related to CSF leak after anterior decompression for OPLL, and data were summarized to identify treatment options for various situations. A treatment algorithm was identified based on these findings and the experience of the authors.

Results

Eleven studies were identified that presented data on intra- and postoperative management of a CSF leak during ventral surgery for OPLL. The incidence of cervical dural tears and CSF leaks after anterior decompression procedures for OPLL ranged from 4.3% to 32%. Techniques including preventative measures, intraoperative dural repair with various materials, and postoperative drainage or shunt placement have all been used.

Conclusions

Although direct dural repair is the preferred treatment for CSF leak, this technique is not always technically possible. In these cases, intraoperative adjuncts in combination with postoperative measures can be used to decrease the pressure gradient across the dural tear.

Anterior versus posterior surgery for multilevel cervical myelopathy, which one is better? A systematic review

The objective of the study is to perform a systematic review to compare the clinical outcomes and complications of anterior surgery with posterior surgery for multilevel cervical myelopathy (MCM). MEDLINE, EMBASE databases and other databases were searched for all the relevant original articles published from January 1991 to November 2009 comparing anterior with posterior surgery for MCM. Subgroup analysis was performed according to the follow-up years. The following end points were mainly evaluated: final follow-up JOA (Japanese Orthopaedic Association) scale, recovery rate and complication outcomes. Ten articles fulfilled all inclusion criteria. For multilevel CSM patients, the final follow-up JOA score for the anterior group was significantly higher than the posterior group (p < 0.05, WMD 0.83 [0.24, 1.43]) in the 'follow-up time ≤ 5 years' subgroup, but had no significant differences in the 'follow-up time > 5 years' subgroup (p > 0.05). The recovery rate for the anterior group was significantly higher than the posterior group (p < 0.05, WMD 10.08 [1.39, 18.78]) in the 'follow-up time ≤ 5 years' subgroup. No study reported the recovery rate for the follow-up time > 5 years. For multilevel OPLL patients, the final follow-up JOA score and recovery rate for the anterior group were both significantly higher than the posterior group in the 'follow-up time ≤ 5 years' subgroup (p < 0.05, WMD 2.50 [0.16, 4.85]; p < 0.05, WMD 29.48 [29.09, 29.87], respectively). One study [31] which mean follow-up time was 6 years was enrolled in the 'follow-up time > 5 years' subgroup. The results showed there was no significant difference in final follow-up JOA score and recovery rate between anterior and posterior group for patients with occupying ratio of OPLL <60% (p > 0.05), while in patients with occupying ratio ≥ 60%, the final follow-up JOA score and recovery rate of anterior surgery were both superior to that of posterior surgery (p < 0.05). For both multilevel CSM and OPLL patients, the complications for the anterior group were significantly more than the posterior group in the 'follow-up time ≤ 5 years' subgroup (p < 0.05, OR 7.33 [2.96, 18.20] for CSM patients; p < 0.05, OR 4.44 [1.80, 10.98] for OPLL patients), but were similar to the posterior group in the 'follow-up time >5 years' subgroup (p > 0.05). In conclusion, anterior surgery had better clinical outcomes and more complications at the early stage after operation for both multilevel CSM and OPLL patients. At the late stage, posterior surgery had similar clinical outcomes and complications to anterior surgery for CSM patients, and OPLL patients with occupying ratio of OPLL <60%. While for OPLL patients with occupying ratio ≥ 60%, anterior surgery had superior clinical outcome to posterior surgery.

Intraoperative spinal subarachnoid hematoma in a patient with cervical ossification of the posterior longitudinal ligament

STUDY DESIGN

Case report.

OBJECTIVE

To report a surgically treated case of cervical ossification of the posterior longitudinal ligament (OPLL), in which a spinal subarachnoid hematoma (SSAH) developed intraoperatively but was successfully treated.

SUMMARY OF BACKGROUND DATA

Previous reports have indicated that trauma, lumbar puncture, vascular lesions such as arteriovenous malformation, neoplastic lesions, and coagulopathy can cause SSAH. To the best of our knowledge, there has been no report that describes the occurrence of SSAH during anterior decompression surgery of the cervical spine.

METHODS

A 52-year-old man with cervical myelopathy caused by OPLL underwent surgery for anterior decompression from C2/3 to C6/7. Immediately after the OPLL floating procedure, cerebrospinal fluid leakage and massive bleeding occurred at right edge of the OPLL at the C3-C4 level. After hemostasis, the dura mater at the C5-C6 levels bulged rapidly and became cyanotic. Intraoperative ultrasonographic images showed a high-intensity mass lesion on the ventral side of the spinal cord, indicating an intrathecal hematoma.

RESULTS

We incised the dura, found the hematoma under the intact arachnoid, and removed it. We then found that the bleeding occurred from the radicular artery along the right C4 root. After hemostasis, we performed anterior spine fusion from C2-C7. After surgery, the patient's myelopathy was improved, and no neurologic deficit related to the subarachnoid hematoma was found.

CONCLUSION

This experience suggests that when anterior decompression surgery is performed for cervical OPLL patients, we should consider the possible occurrence of an SSAH. Intraoperative ultrasonography is a useful tool for detecting SSAHs.

Revision surgery following cervical laminoplasty: etiology and treatment strategies

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To identify the cause of failed open-door laminoplasty and to describe the surgical strategies for revision surgery.

SUMMARY OF BACKGROUND DATA

Although laminoplasty has become popular, few articles have addressed the cause of failed cervical laminoplasty requiring revision surgery.

METHODS

All patients who required revision surgery following open-door cervical laminoplasty were identified. Clinical data, method of surgical revision, time between surgeries, Nurick grade, radiologic parameters, and complications were analyzed. Laminoplasty failures were classified into 3 categories: "technique related," "inadequate symptomatic relief after treatment," or "recurrence of symptoms due to disease progression."

RESULTS

A total of 130 patients underwent cervical laminoplasty over a 10-year period (1996-2006), and 12 patients (9.2%) required revision surgery. The mean age was 50.7 years at the time of the index laminoplasty (range, 34-67 years) and 51.8 years (range, 35-70 years) at the time of the revision surgery. Mean duration of symptoms was 7.3 months before the index procedure (range, 2-17 months) and 5.6 months (range, 1-14 months) before revision surgery. The mean time interval between the index procedure and revision surgery was 16.6 months (range, 4-43 months). Of the 12 patients who required revision surgery, 5 had global lordosis of <10 degrees, 4 developed local kyphosis >13 degrees, and 5 had increased degenerative spondylolisthesis. Nonmyelopathic causes resulted in 50% of the revision surgery. Of 12 patients, 3 (25%) required revision surgery due to technique-related factors; 1 (8%) required surgery due to inadequate symptomatic relief after treatment; and 8 (67%) required revision surgery due to disease progression.

CONCLUSION

Of the 130 patients who underwent cervical laminoplasty over a 10-year period, 12 patients (9.2%) required revision surgery. Although laminoplasty is generally successful, failures due to disease progression, technique-related factors, and inadequate symptomatic relief after treatment can occur. Patients should, therefore, be counseled regarding the potential need for revision surgery when undergoing open-door laminoplasty.

Adjacent level ossification development after anterior cervical fusion without plate fixation

STUDY DESIGN

A retrospective.

OBJECTIVE

The proximity of the plate to the adjacent disc space appeared to be the critical determinant of adjacent level ossification development (ALOD) but we had no data on unplated arthrodesis. Without such data, we could not be positive that ALOD was a complication related to plates.

SUMMARY OF BACKGROUND DATA

We previously described the incidence and timing of ALOD after anterior cervical arthrodesis and plating.

METHODS

One hundred sixty-five patients (total 330 adjacent levels) who underwent anterior cervical arthrodesis without plate fixation by a single surgeon were reviewed. The average follow-up period was 28.8 months (2-9 years); ages ranged from 32 to 79 years (median 59.86). The presence and severity of ALOD was assessed on the lateral radiographs at 3, 6, 12, and 24 months after surgery and then annually and recorded into 4 grades.

RESULTS

ALOD developed in 9 patients at 10 levels (5.5% of patients and 3% of levels). Eight patients had a single-level (proximal or distal) ALOD, whereas 1 patient had both ALOD. Proximal ALOD developed in 7 cases, distal in 1 case and both in 1 case. ALOD initially appeared between 6 and 12 months in all cases: 4 cases occurred at 6 months and 5 cases at 12 months. During follow-up period, the final grade of proximal ALOD was grade I for 4 levels and grade II for 4 levels and final grade of distal ALOD was grade I for 1 level and grade II for 1 level. One patient with C3-C4 arthrodesis had both ALOD with grade I proximally and grade II distally.

CONCLUSION

ALOD is infrequent when certain techniques are adhered to. These include minimal stripping of the anterior longitudinal ligament and the avoidance of Caspar pins and anterior plates. It remains to be determined exactly which of these factors plays the dominant role in the production of ALOD.

Adverse events associated with anterior cervical spine surgery

Anterior cervical procedures for neurologic decompression and fusion, including cervical diskectomy and cervical corpectomy, are commonly performed by orthopaedic surgeons and spinal neurosurgeons. These procedures are highly successful in treating most patients with persistent pain and neurologic symptoms that have not responded to nonsurgical methods. Adverse events occur infrequently, but several have been described, including esophageal injury, vertebral artery injury, dural tear, postoperative airway compromise, spinal cord injury, hematoma, dysphagia, dysphonia, and graft dislodgement. Newer procedures, such as cervical total disk replacement and the use of bone morphogenetic protein as a supplement to fusion, have raised unique concerns. Appropriate strategies must be utilized to avoid these adverse events, and the treating surgeon should have an understanding of how to detect and manage such events when they do arise.

Laser-assisted anterior cervical corpectomy versus posterior laminoplasty for cervical myelopathic patients with multilevel ossification of the posterior longitudinal ligament

OBJECTIVE

This study reports on the comparative results of a series of patients with multilevel cervical ossification of the posterior longitudinal ligament (OPLL) who were treated with laser-assisted anterior corpectomy or laminoplasty.

METHODS

Forty-eight patients (21 patients with anterior corpectomy and 27 patients with laminoplasty) with cervical OPLL involvement of three or more vertebral bodies were retrospectively reviewed. Both pre- and postoperatively neurological status was graded according to the Nurick grading system. The anteroposterior (AP) diameter change at the narrowest part of the spinal canal, the change in the regional and the overall cervical Cobb's angle, and the change in cervical range of motion (ROM) were all measured. The mean follow-up periods were 21.8 mo and 29.1 mo for the corpectomy and laminoplasty patients, respectively.

RESULTS

The mean changes in the pre- to postoperative Nurick grades were 1.9 for the corpectomy group and 1 for the laminoplasty group (p < 0.05). The mean changes in the pre- to postoperative spinal canal AP diameters were 9.1 mm and 4.11 mm, respectively, for the corpectomy group and the laminoplasty group (p < 0.05). The mean changes of the regional Cobb's angle were 1.7 degrees and -3.1 degrees (p = 0.06), and the mean changes of the overall cervical Cobb's angle were 1.1 degrees and -1.6 degrees , respectively, for the corpectomy group and the laminoplasty group (p > 0.05). The changes in the cervical degree of ROM were -19.6 degrees and -19.7 degrees , respectively, for the corpectomy group and the laminoplasty group (p > 0.05).

CONCLUSIONS

Direct decompression of the spinal cord by laser-assisted anterior cervical corpectomy was shown to be a better surgical option on long-term follow-up, yielding more recovery of neurological deficits, achieving adequate decompression of the spinal canal, and preventing the development of regional kyphosis at the operated level of the spine, in patients with multilevel cervical OPLL.

Surgical strategy for cervical myelopathy due to ossification of the posterior longitudinal ligament: Part 1: Clinical results and limitations of laminoplasty

STUDY DESIGN

Retrospective study of 66 patients who underwent laminoplasty for treatment of cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL).

OBJECTIVES

The present study describes surgical results of laminoplasty for treatment of cervical myelopathy due to OPLL and aims to clarify 1) factors predicting outcome and 2) limitations of laminoplasty.

SUMMARY OF BACKGROUND DATA

During the period 1986 and 1996, laminoplasty was the only surgical treatment selected for cervical myelopathy at our institutions.

METHODS

We reviewed data obtained in 66 patients who underwent laminoplasty for treatment of cervical myelopathy due to OPLL. Mean duration of follow-up was 10.2 years (range, 5-20 years). Surgical outcomes were assessed using the Japanese Orthopaedic Association (JOA) scoring system for cervical myelopathy.

RESULTS

Surgical outcome was significantly poorer in patients with occupying ratio greater than 60%. Multiple regression analysis showed that the most significant predictor of poor outcome after laminoplasty was hill-shaped ossification, followed by lower preoperative JOA score, postoperative change in cervical alignment, and older age at surgery.

CONCLUSIONS

Laminoplasty is effective and safe for most patients with occupying ratio of OPLL less than 60% and plateau-shaped ossification. However, neurologic outcome of laminoplasty for cervical OPLL was poor or fair in patients with occupying ratio greater than 60% and/or hill-shaped ossification.

Complication avoidance: thoracolumbar and lumbar burst fractures

Most thoracolumbar and lumbar burst fractures can be treated conservatively. Unstable fractures or fractures resulting in neurologic deficits usually require surgical treatment. Choosing an appropriate surgical approach requires a thorough understanding of the various techniques for decompression, fusion, and stabilization. Surgical options include an anterior approach, a posterior approach, or a combined anteroposterior approach. Each surgical option has unique advantages and disadvantages. Generally, the anterior approaches are best used at the thoracolumbar junction, posterior approaches are ideal for low lumbar injuries and lumbar injuries that result in complete spinal cord injuries,and anteroposterior surgeries typically are reserved for highly unstable fracture subluxations. Case illustrations show the various treatment options.

Decision-making in burst fractures of the thoracolumbar and lumbar spine

The most common site of injury to the spine is the thoracolumbar junction which is the mechanical transition junction between the rigid thoracic and the more flexible lumbar spine. The lumbar spine is another site which is more prone to injury. Absence of stabilizing articulations with the ribs, lordotic posture and more sagitally oriented facet joints are the most obvious explanations. Burst fractures of the spine account for 14% of all spinal injuries. Though common, thoracolumbar and lumbar burst fractures present a number of important treatment challenges. There has been substantial controversy related to the indications for nonoperative or operative management of these fractures. Disagreement also exists regarding the choice of the surgical approach. A large number of thoracolumbar and lumbar fractures can be treated conservatively while some fractures require surgery. Selecting an appropriate surgical option requires an in-depth understanding of the different methods of decompression, stabilization and/or fusion. Anterior surgery has the advantage of the greatest degree of canal decompression and offers the benefit of limiting the number of motion segments fused. These advantages come at the added cost of increased time for the surgery and the related morbidity of the surgical approach. Posterior surgery enjoys the advantage of being more familiar to the operating surgeons and can be an effective approach. However, the limitations of this approach include inadequate decompression, recurrence of the deformity and implant failure. Though many of the principles are the same, the treatment of low lumbar burst fractures requires some additional consideration due to the difficulty of approaching this region anteriorly. Avoiding complications of these surgeries are another important aspect and can be achieved by following an algorithmic approach to patient assessment, proper radiological examination and precision in decision-making regarding management. A detailed understanding of the mechanism of injury and their unique biomechanical propensities following various forms of treatment can help the spinal surgeon manage such patients effectively and prevent devastating complications.