Advances in surgical strategies for ossification of posterior longitudinal ligament involving the C 2 segment / 中国修复重建外科杂志

OBJECTIVE@#To evaluate the application of surgical strategies for the treatment of cervical ossification of the posterior longitudinal ligament (OPLL) involving the C 2 segment.@*METHODS@#The literature about the surgery for cervical OPLL involving C 2 segment was reviewed, and the indications, advantages, and disadvantages of surgery were summarized.@*RESULTS@#For cervical OPLL involving the C 2 segments, laminectomy is suitable for patients with OPLL involving multiple segments, often combined with screw fixation, and has the advantages of adequate decompression and restoration of cervical curvature, with the disadvantages of loss of cervical fixed segmental mobility. Canal-expansive laminoplasty is suitable for patients with positive K-line and has the advantages of simple operation and preservation of cervical segmental mobility, and the disadvantages include progression of ossification, axial symptoms, and fracture of the portal axis. Dome-like laminoplasty is suitable for patients without kyphosis/cervical instability and with negative R-line, and can reduce the occurrence of axial symptoms, with the disadvantage of limited decompression. The Shelter technique is suitable for patients with single/double segments and canal encroachment >50% and allows for direct decompression, but is technically demanding and involves risk of dural tear and nerve injury. Double-dome laminoplasty is suitable for patients without kyphosis/cervical instability. Its advantages are the reduction of damage to the cervical semispinal muscles and attachment points and maintenance of cervical curvature, but there is progress in postoperative ossification.@*CONCLUSION@#OPLL involving the C 2 segment is a complex subtype of cervical OPLL, which is mainly treated through posterior surgery. However, the degree of spinal cord floatation is limited, and with the progress of ossification, the long-term effectiveness is poor. More research is needed to address the etiology of OPLL and to establish a systematic treatment strategy for cervical OPLL involving the C 2 segment.

Surgical Reconstruction Using a Flanged Mesh Cage without Plating for Cervical Spondylotic Myelopathy and a Symptomatic Ossified Posterior Longitudinal Ligament

OBJECTIVE: We introduce innovative method of cervical column reconstruction and performed the reconstruction with a flanged titanium mesh cage (TMC) instead of a plate after anterior corpectomy for cervical spondylotic myelopathy (CSM) and an ossified posterior longitudinal ligament (OPLL).METHODS: Fifty patients with CSM or OPLL who underwent anterior cervical reconstruction with a flanged TMC were investigated retrospectively. Odom’s criteria were used to assess the clinical outcomes. The radiographic evaluation included TMC subsidence, fusion status, and interbody height. Thirty-eight patients underwent single-level and 12 patients underwent two-level corpectomy with a mean follow-up period of 16.8 months.RESULTS: In all, 19 patients (38%) had excellent outcomes and 25 patients (50%) had good outcomes. Two patients (4%) in whom C5 palsy occurred were categorized as poor. The fusion rate at the last follow-up was 98%, and the severe subsidence rate was 34%. No differences in subsidence were observed among Odom’s criteria or between the single-level and two-level corpectomy groups.CONCLUSION: The satisfactory outcomes in this study indicate that the flanged TMC is an effective graft for cervical reconstruction.

Surgical Reconstruction Using a Flanged Mesh Cage without Plating for Cervical Spondylotic Myelopathy and a Symptomatic Ossified Posterior Longitudinal Ligament

OBJECTIVE: We introduce innovative method of cervical column reconstruction and performed the reconstruction with a flanged titanium mesh cage (TMC) instead of a plate after anterior corpectomy for cervical spondylotic myelopathy (CSM) and an ossified posterior longitudinal ligament (OPLL). METHODS: Fifty patients with CSM or OPLL who underwent anterior cervical reconstruction with a flanged TMC were investigated retrospectively. Odom’s criteria were used to assess the clinical outcomes. The radiographic evaluation included TMC subsidence, fusion status, and interbody height. Thirty-eight patients underwent single-level and 12 patients underwent two-level corpectomy with a mean follow-up period of 16.8 months. RESULTS: In all, 19 patients (38%) had excellent outcomes and 25 patients (50%) had good outcomes. Two patients (4%) in whom C5 palsy occurred were categorized as poor. The fusion rate at the last follow-up was 98%, and the severe subsidence rate was 34%. No differences in subsidence were observed among Odom’s criteria or between the single-level and two-level corpectomy groups. CONCLUSION: The satisfactory outcomes in this study indicate that the flanged TMC is an effective graft for cervical reconstruction.

Comparison of multi-mode and single-mode intraoperative neurophysiological monitoring in the treatment of severe ossification of the cervical posterior longitudinal ligament with anterior cervical corpectomy with fusion / 中国骨伤

OBJECTIVE@#To compare the application of multi-mode and single-mode intraoperative neurophysiological monitoring in the treatment of severe ossification of posterior longitudinal ligament of cervical spine with anterior cervical corpectomy with fusion.@*METHODS@#From April 2015 to June 2018, 32 patients with severe ossification of the posterior longitudinal ligament were treated in the Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine. There were 21 males and 11 females, aged 45 to 73 years old, with a mean age of 59 years old. The duration of the disease ranged from 6 to 72 months, with a mean of 39 months. The main manifestations were numbness, numbness and weakness of limbs, cotton feeling of foot stepping on lower limbs, instability of standing and walking. With the gradual aggravation of symptoms, quadriplegia, dysfunction of urine and defecation may occur. Patients with ossification of posterior longitudinal ligament of cervical spine were monitored by somatosensory evoked potentials, motor evoked potentials and electromyogram patterns.@*RESULTS@#During the operation, 8 patients had abnormal amplitude of somatosensory evoked potential(SEP); 5 of them had bleeding during anterior cervical decompression procedure and were placed with too much hemostatic cotton, which caused compression of spinal cord and resulted in abnormal SEP waveform. After removal of the hemostatic cotton, SEP waveform returned ot normal; 3 patients had abnormal SEP waveform due to decreased systolic pressure, which was corrected by increased systolic pressure. Twelve patients had abnormal amplitude of motor evoked potential during monitoring, 9 of which were caused by intraoperative mis-contact with nerve root, and turned to normal after timely adjustment of position, 3 of which were caused by intraoperative inhalation of muscle relaxant during surgery. Among 11 patients with abnormal EMG waveform, 9 patients recovered to normal waveform after adjusting operation, 2 patients recovered to normal waveform after short observation, and all patients recovered to normal waveform of motor evoked potential after operation(<0.05). There were 2 cases of cerebrospinal fluid leakage after operation, which healed spontaneously 7 days after operation, and no complications of spinal cord and nerve occurred in all patients after operation.@*CONCLUSIONS@#In anterior cervical corpectomy with fusion operation for the treatment of severe cervical ossification of posterior longitudinal ligament, various modes of intraoperative neurophysiological monitoring can real-time understand spinal cord and nerve function status, significantly reduce the incidence of spinal cord and nerve injury during operation, and effectively improve the safety of operation.

Relationship between the Progression of Kyphosis in Thoracolumbar Osteoporotic Vertebral Compression Fractures and Magnetic Resonance Imaging Findings / 대한정형외과학회잡지

PURPOSE: To examine the relationship between the progression of a kyphotic deformity and the magnetic resonance imaging (MRI) findings in conservatively treated osteoporotic thoracolumbar compression fracture patients. MATERIALS AND METHODS: This study categorized the patients who underwent conservative treatment among those patients who underwent treatment under the suspicion of a thoracolumbar compression fracture from January 2007 to March 2016. Among them, this retrospective study included eighty-nine patients with osteoporosis and osteopenia with a bone density of less than −2.0 and single vertebral body fracture. This study examined the MRI of anterior longitudinal ligament or posterior longitudinal ligament injury, superior or inferior endplate disruption, superior of inferior intravertebral disc injury, the presence of low signal intensity on T2-weighted images, and bone edema of intravertebral bodies in fractured intravertebral bodies. RESULTS: In cases where the superior endplate was disrupted or the level of bone edema of the intravertebral bodies was high, the kyphotic angle, wedge angle, and anterior vertebral compression showed remarkably progression. In the case of damage to the anterior longitudinal ligament or the superior disc, only the kyphotic angle was markedly prominent. On the T2-weighted images, low signal intensity lesions showed a high wedge angle and high anterior vertebral compression. On the other hand, there were no significant correlations among the posterior longitudinal ligament injury, inferior endplate disruption, inferior disc injury, and the progression of kyphotic deformity and vertebral compression. The risk factors that increase the kyphotic angle by more than 5° include the presence of injuries to the anterior longitudinal ligament, superior endplate disruption, and superior disc injury, and the risk factors were 21.3, 5.1, and 8.5 times higher than those of the uninjured case, and the risk differed according to the level of bone edema. CONCLUSION: An osteoporotic thoracolumbar compression fracture in osteoporotic or osteopenic patients, anterior longitudinal ligament injury, superior endplate and intravertebral disc injury, and high level of edema in the MRI were critical factors that increases the risk of kyphotic deformity.

Molecular Pathophysiology of Ossification of the Posterior Longitudinal Ligament (OPLL)

Ossification of the posterior longitudinal ligament (OPLL) can be defined as an ectopic ossification in the tissues of spinal ligament showing a hyperostotic condition. OPLL is developed mostly in the cervical spine and clinical presentations of OPLL are majorly myelopathy and/or radiculopathy, with serious neurological pathology resulting in paralysis of extremities and disturbances of motility lowering the quality of life. OPLL is known to be an idiopathic and multifactorial disease, which genetic factors and non-genetic factors including diet, obesity, physical strain on the posterior longitudinal ligament, age, and diabetes mellitus, are involved into the pathogenesis. Up to now, surgical management by decompressing the spinal cord is regarded as standard treatment for OPLL, although there might be the risk of development of reprogression of ossification. The molecular pathogenesis and efficient therapeutic strategy, especially pharmacotherapy and/or preventive intervention, of OPLL has not been clearly elucidated and suggested. Therefore, in this review, we tried to give an overview to the present research results on OPLL, in order to shed light on the potential pharmacotherapy based on molecular pathophysiologic aspect of OPLL, especially on the genetic/genomic factors involved into the etiology of OPLL.

Influence of Diabetes Mellitus on Surgical Outcomes in Patients with Cervical Myelopathy: A Prospective, Multicenter Study

STUDY DESIGN: Multicenter, prospective study. PURPOSE: To investigate the effects of diabetes mellitus (DM) on surgical outcomes in patients with cervical myelopathy. OVERVIEW OF LITERATURE: To date, few studies have investigated the influence of postoperative blood glucose or glycated hemoglobin (HbA1c) levels on surgical outcomes. METHODS: The participants were patients who underwent surgery for the treatment of cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament. The 61 cases were evaluated preoperatively and 1 year postoperatively using the Japanese Orthopaedic Association (JOA) scores and the JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ). The study variables included fasting blood glucose and HbA1c levels measured preoperatively and at 1 week, 4 weeks, and 1 year postoperatively; the F-wave conduction velocity, latency, rate of occurrence, and M-wave latency in the ulnar and tibial nerves were measured preoperatively and at 1 year postoperatively. The patients were divided into a group without diabetes (N group, 42 patients) and a group with diabetes (DM group, 19 patients). We then assessed the associations between the surgical outcomes and each of the study variables. RESULTS: JOA scores significantly improved in both groups; however, no significant between-group differences were found. There was no significant improvement in the JOACMEQ scores, which assessed cervical function, upper and lower limb function, and bladder function in both groups. We then subdivided the DM group into those with a good control of HbA1c after 1 year (DMG group, 12 patients) and those with HbA1c deterioration after 1 year (DMB group, seven patients), prior to comparing the surgical outcomes. The JOACMEQ scores for upper and lower limb function significantly improved in the DMG group (p<0.01). Compared with the DMB group, there were no significant increases in upper or lower limb function scores in the DMG group. CONCLUSIONS: Poor glycemic control might prevent postoperative functional recovery of the spinal cord.

Progression of Ossification of the Posterior Longitudinal Ligament after Cervical Total Disc Replacement / 대한신경손상학회지

OBJECTIVE: Total disc replacement (TDR) is frequently performed anterior approaching method for the patients diagnosed with cervical disc herniation. This study aimed to assess the degree of ossification of the posterior longitudinal ligament (OPLL) progression after cervical TDR. METHODS: Twenty-two male soldiers who underwent cervical TDR surgery from 2009 to 2016 and were followed-up for more than 12 months were enrolled. The enrolled patients were classified as; 1) patients with pre-existing OPLL and without; and 2) patient showing progression of OPLL or not. RESULTS: Twenty-two men were included in the analysis. The mean follow-up period from the surgery was 41.4 months (range, 12–114 months). The mean age of all patients was 40.7 years (range, 31–52 years). TDR-only was used in 7 cases, and the hybrid surgery (TDR+ACDF) was used in 15 cases. The incidence of progression or newly development of OPLL was significantly higher in pre-existing OPLL group (p=0.01). In 11 cases showing the progression of the OPLL, the mean size of OPLL progression was 4.16 mm (range, 0.34–18.87 mm) in the longitudinal height and 1.57 mm (range, 0.54–3.91 mm) in thickness. CONCLUSION: The progression of OPLL after cervical TDR was more frequent in patients with pre-existing OPLL than in patients without OPLL. Even though TDR is a major alternative to the treatment of cervical lesions to preserve vertebral segmental motion, careful attention should be paid to whether TDR should be used in patients with OPLL and this should be fully explained to the patient.

Unión cráneo-cervical - anatomía normal y correlación con imágenes / Cranio Cervical Junction - Anatomy and Imaging Correlation

La solicitud de estudios de imagen en pacientes con trauma cervical es muy frecuente en la práctica diaria. Esa patología es causa relativamente frecuente de discapacidad en pacientes jóvenes junto con el trauma encéfalo craneano. En un porcentaje no despreciable de los casos, las lesiones traumáticas comprometen la unión cráneo- cervical y en esos pacientes, la morbi-mortalidad es más significativa. La transición entre el cráneo y el raquis se basa en un conjunto de estructuras óseas relacionadas por articulaciones muy móviles y estabilizadas por un grupo de ligamentos y músculos que le brindan al mismo tiempo gran solidez. Para una correcta interpretación de los estudios de imagen de uso corriente en la clínica, es fundamental un sólido conocimiento anatómico de la unión cráneo-cervical y sus componentes. Es el objetivo de esta revisión, sistematizar la anatomía de la unión cráneo-cervical con especial énfasis en sus ligamentos, analizar la fisiología de sus movimientos y el concepto de estabilidad para luego realizar una correlación con tomografía computada multi-detector y resonancia magnética.

The request of imaging techniques in patients with cervical spine trauma is very common in clinical practice. Cervical trauma is a relatively common cause of disability in young patients. In a significant percentage of cases traumatic injuries compromise the cranio-cervical junction with more important morbidity and mortality in this group of patients. The transition between the skull and the spine is based on a set of bony structures, high mobility joints, and stabilization mechanism formed by a group of ligaments and muscles. A solid anatomical knowledge of the cranio-cervical junction and its components is essential for a correct interpretation of current high resolution imaging studies. The goal of this review is highlight the anatomy of the cranio-cervical junction with special emphasis on the ligaments, analyze the biomechanics of their movements and the concept of stability. At last but not leastwe will establish a correlation with multidetector computed tomography and high-resolutionmagnetic resonance imaging.

Effect of table tilt and spine flexion-rotation on the acoustic window of the lumbar spine in pregnant women / Efeito da inclinação da mesa e flexão da coluna sobre a janela acústica da coluna lombar em mulheres grávidas

Abstract Study objective: The purpose of this study was to assess whether application of dorsal table tilt and body rotation to a parturient seated for neuraxial anesthesia increased the size of the paramedian target area for neuraxial needle insertion. Setting: Labor and Delivery Room. Patients: Thirty term pregnant women, ASA I-II, scheduled for an elective C-section delivery. Interventions: Lumbar ultrasonography was performed in four seated positions: (F) lumbar flexion; (FR) as in position F with right shoulder rotation; (FT) as in position F with dorsal table-tilt; (FTR) as in position F with dorsal table-tilt combined with right shoulder rotation. Measurements: For each position, the size of the 'target area', defined as the visible length of the posterior longitudinal ligament was measured at the L3-L4 interspace. Main results: The mean posterior longitudinal ligament was 18.4 ± 4 mm in position F, 18.9 ± 5.5 mm in FR, 19 ± 5.3 mm in FT, and 18 ± 5.2 mm in FTR. Mean posterior longitudinal ligament length was not significantly different in the four positions. Conclusions: These data show that the positions studied did not increase the target area as defined by the length of the posterior longitudinal ligament for the purpose of neuraxial needle insertion in obstetric patients. The maneuvers studied will have limited use in improving spinal needle access in pregnant women.

Resumo Objetivo do estudo: O objetivo deste estudo foi avaliar se a inclinação lateral da mesa cirúrgica e a rotação do corpo de uma parturiente sentada para anestesia neuraxial aumentou o tamanho da área-alvo paramediana para a inserção da agulha neuraxial. Ambiente: Sala de parto. Pacientes: Trinta grávidas a termo, ASA I-II, agendadas para cesárea eletiva. Intervenções: Ultrassonografia lombar foi feita em quatro posições sentadas: (F) flexão lombar; (FR) como na posição F com rotação do ombro direito; (FT) como na posição F com inclinação lateral da mesa cirúrgica; (FTR) como na posição F com inclinação lateral da mesa cirúrgica combinada com a rotação do ombro direito. Mensurações: Para cada posição, o tamanho da "área-alvo", definido como o comprimento visível do ligamento longitudinal posterior, foi medido no interespaço de L3-L4. Principais resultados: As médias do ligamento longitudinal posterior foram: 18,4 ± 4 mm na posição F; 18,9 ± 5,5 mm na posição FR; 19 ± 5,3 mm na posição FT e 18 ± 5,2 mm na posição FTR. O comprimento médio do ligamento longitudinal posterior não foi significativamente diferente nas quatro posições. Conclusões: Esses dados mostram que as posições avaliadas não aumentaram a área-alvo, conforme definido pelo comprimento do ligamento longitudinal posterior com o objetivo de inserção da agulha neuraxial em pacientes obstétricas. As manobras avaliadas terão um uso limitado na melhoria do acesso à agulha espinhal em mulheres grávidas.

Investigation of Symptomatic Unstable Changes of Non-Fused Component in the Mixed-Type Cervical Ossification of Posterior Longitudinal Ligament Using Dynamic Magnetic Resonance Imaging: A Case Report / 대한신경손상학회지

A 43-year-old man was transferred to our hospital with recurring myelopathic symptoms after previous anterior and posterior surgical decompressions for mixed-type cervical ossification of the posterior longitudinal ligament (OPLL). Conventional magnetic resonance imaging (MRI) showed a preserved cervical curve and the achievement of successful decompression after the previous surgeries. The patient's symptoms were aggravated when he was in the extended neck posture. Dynamic MRI performed with the patient in an extended neck position revealed cord compression by OPLL from C3 to C4 with newly developed retrolisthesis of the C4–5 segment. We recommend the use of dynamic MRI to investigate motion-dependent cord compression caused by instability of the non-fused OPLL component.

Prevalence of diffuse idiopathic skeletal hyperostosis among elderly subjects referred for radiological investigation in tertiary hospital at Oman / 대한해부학회지

Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by calcification of different entheseal sites including the anterior longitudinal ligament of the spine. There is no documented information about DISH in Oman. This study determined the prevalence of DISH and associated factors among elderly subjects in a national tertiary care referral hospital in Oman. This retrospective study reviewed chest X-rays of all patients aged more than 50 years, referred to the radiology department of Sultan Qaboos University Hospital in the year 2016, based on the Resnick's criteria. The prevalence was expressed as proportions across age groups and sex. Chi-square test and logistic regression analysis was done to determine the association of the age and sex with DISH. A total of 1305 chest X-rays of patients were reviewed. The overall prevalence of DISH was 10%, with male to female ratio of 1.56:1. The odds ratio for males and increasing age were 1.63 (95% confidence interval [CI], 1.12–2.3; P<0.05) and 1.34 (95% CI, 1.14–1.58; P<0.001) respectively. The prevalence increased with age to maximum of 13% in the age group of ≤80. The pre-stage DISH prevalence was 9.3% and more frequently observed among males. Prevalence of DISH in the national tertiary care referral center in Oman is lower than in Jewish population, almost similar to Japanese, but higher than in Koreans. DISH prevalence is positively associated with age and sex. It is necessary to take appropriate precautionary measures to target the ageing population in Oman, especially elderly males.

Analysis of Factors Contributing to Repeat Surgery in Multi-Segments Cervical Ossification of Posterior Longitudinal Ligament

OBJECTIVE: Cervical ossification of the posterior longitudinal ligament (OPLL) can be treated via anterior or posterior approach, or both. The optimal approach depends on the characteristics of OPLL and cervical curvature. Although most patients can be successfully treated by a single surgery with the proper approach, renewed or newly developed neurological deterioration often requires repeat surgery.METHODS: Twenty-seven patients with renewed or newly developed neurological deterioration requiring salvage surgery for multi-segment cervical OPLL were enrolled. Ten patients (group AP) underwent anterior approach, and 17 patients (group PA) underwent posterior approach at the initial surgery. Clinical and radiological data from initial and repeat surgeries were obtained and analyzed retrospectively.RESULTS: The intervals between the initial and repeat surgeries were 102.80±60.08 months (group AP) and 61.00±8.16 months (group PA) (p < 0.05). In group AP, the main OPLL lesions were removed during the initial surgery. There was a tendency that the site of main OPLL lesions causing renewed or newly developed neurological deterioration were different from that of the initial surgery (8/10, p < 0.05). Repeat surgery was performed for progressed OPLL lesions at another segment as the main pathology. In group PA, the main OPLL lesions at the initial surgery continued as the main pathology for repeat surgery. Progression of kyphosis in the cervical curvature (Cobb’s angle on C2–7 and segmental angle on the main OPLL lesion) was noted between the initial and repeat surgeries. Group PA showed more kyphotic cervical curvature compared to group AP at the time of repeat surgery (p < 0.05).CONCLUSION: The reasons for repeat surgery depend on the type of initial surgery. The main factors leading to repeat surgery are progression of remnant OPLL at a different segment in group AP and kyphotic change of the cervical curvature in group PA.

Morphometric Study of the Lumbar Posterior Longitudinal Ligament

OBJECTIVE: Morphometric data for the lumbar posterior longitudinal ligament (PLL) was investigated to identify whether there is a difference in the morphometry of the PLL of the lumbar spine at each level with respect to the pattern of intervertebral disc displacement.METHODS: In 14 formalin-fixed adult cadavers (12 males and 2 females), from L1 to L5, the authors measured the width and height of the PLL and compared them with other landmarks such as the disc and the pedicle.RESULTS: Horizontally, at the upper margin of the disc, the central portion of the superficial PLL covered 17.8–36.9% of the disc width and the fan-like portion of the PLL covered 63.9–76.7% of the disc width. At the level of the median portion of the disc, the PLL covered 69.1–74.5% of the disc width. Vertically, at the level of the medial margin of the pedicle, the fan-like portion of the PLL covered 23.5–29.9% of the disc height. In general, a significant difference in length was not found in the right-left and male-female comparisons.CONCLUSION: This study presents the morphometric data on the pattern of intervertebral disc displacement and helps to improve the knowledge of the surgical anatomy of the lumbar PLL.

Analysis of Factors Contributing to Repeat Surgery in Multi-Segments Cervical Ossification of Posterior Longitudinal Ligament

OBJECTIVE: Cervical ossification of the posterior longitudinal ligament (OPLL) can be treated via anterior or posterior approach, or both. The optimal approach depends on the characteristics of OPLL and cervical curvature. Although most patients can be successfully treated by a single surgery with the proper approach, renewed or newly developed neurological deterioration often requires repeat surgery. METHODS: Twenty-seven patients with renewed or newly developed neurological deterioration requiring salvage surgery for multi-segment cervical OPLL were enrolled. Ten patients (group AP) underwent anterior approach, and 17 patients (group PA) underwent posterior approach at the initial surgery. Clinical and radiological data from initial and repeat surgeries were obtained and analyzed retrospectively. RESULTS: The intervals between the initial and repeat surgeries were 102.80±60.08 months (group AP) and 61.00±8.16 months (group PA) (p < 0.05). In group AP, the main OPLL lesions were removed during the initial surgery. There was a tendency that the site of main OPLL lesions causing renewed or newly developed neurological deterioration were different from that of the initial surgery (8/10, p < 0.05). Repeat surgery was performed for progressed OPLL lesions at another segment as the main pathology. In group PA, the main OPLL lesions at the initial surgery continued as the main pathology for repeat surgery. Progression of kyphosis in the cervical curvature (Cobb’s angle on C2–7 and segmental angle on the main OPLL lesion) was noted between the initial and repeat surgeries. Group PA showed more kyphotic cervical curvature compared to group AP at the time of repeat surgery (p < 0.05). CONCLUSION: The reasons for repeat surgery depend on the type of initial surgery. The main factors leading to repeat surgery are progression of remnant OPLL at a different segment in group AP and kyphotic change of the cervical curvature in group PA.

Morphometric Study of the Lumbar Posterior Longitudinal Ligament

OBJECTIVE: Morphometric data for the lumbar posterior longitudinal ligament (PLL) was investigated to identify whether there is a difference in the morphometry of the PLL of the lumbar spine at each level with respect to the pattern of intervertebral disc displacement. METHODS: In 14 formalin-fixed adult cadavers (12 males and 2 females), from L1 to L5, the authors measured the width and height of the PLL and compared them with other landmarks such as the disc and the pedicle. RESULTS: Horizontally, at the upper margin of the disc, the central portion of the superficial PLL covered 17.8–36.9% of the disc width and the fan-like portion of the PLL covered 63.9–76.7% of the disc width. At the level of the median portion of the disc, the PLL covered 69.1–74.5% of the disc width. Vertically, at the level of the medial margin of the pedicle, the fan-like portion of the PLL covered 23.5–29.9% of the disc height. In general, a significant difference in length was not found in the right-left and male-female comparisons. CONCLUSION: This study presents the morphometric data on the pattern of intervertebral disc displacement and helps to improve the knowledge of the surgical anatomy of the lumbar PLL.

Prevalence of Diffuse Idiopathic Skeletal Hyperostosis Diagnosed by Whole Spine Computed Tomography: A Preliminary Study

BACKGROUND: Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by ossification of the enthesis. The diagnosis has been mainly based on the chest or whole spine lateral plain film. Recently, chest or thoracolumbar computed tomography (CT) has been reported to be more reliable for the diagnosis of DISH. The purposes of this study were to investigate the prevalence and location of DISH and evaluate the prevalence of comorbidities, such as ossification of the posterior longitudinal ligament (OPLL) and ossification of the ligamentum flavum (OLF), using whole spine CT. METHODS: Whole spine CT scans of patients over 16 years of age who were examined at Cheju Halla General Hospital between February 2011 and December 2016 were reviewed for this study. The diagnosis of DISH was made according to the modified Resnick criteria. The prevalence of DISH in each age decade and its location were evaluated. Also, the prevalence of OPLL and OLF in DISH patients was investigated. RESULTS: The overall incidence of DISH was 24.4% (40 of 164 cases). There was no case of DISH in patients in their 40s and younger. The percentile incidences of DISH in patients in their fifth, sixth, seventh, eighth, and ninth decades were 20.0% (4 of 20 cases), 32.3% (10 of 31 cases), 40.0% (10 of 25 cases), 34.5% (10 of 29 cases), and 27.3% (6 of 22 cases), respectively. A strong positive correlation between the age decade and the incidence of DISH was noted (r = 0.853, p = 0.007). DISH patients had higher incidences of OLF (22.5%) and OPLL (37.5%). The most common location of DISH was the middle thoracic spine (90.0%) followed by the lower thoracic spine (87.5%). There was one case of DISH involving only the cervical spine. CONCLUSIONS: The incidence of DISH diagnosed by CT was higher than we expected. Whole spine CT can be a valuable modality to evaluate the location of DISH in the cervical and lumbar spine and the comorbidity rates of OLF and OPLL.

Inter- and Intra-Observer Variability of the Volume of Cervical Ossification of the Posterior Longitudinal Ligament Using Medical Image Processing Software

OBJECTIVE: Computed tomography (CT)-based method of three dimensional (3D) analysis (MIMICS®, Materialise, Leuven, Belgium) is reported as very useful software for evaluation of OPLL, but its reliability and reproducibility are obscure. This study was conducted to evaluate the accuracy of MIMICS® system, and inter- and intra-observer reliability in the measurement of OPLL. METHODS: Three neurosurgeons independently analyzed the randomly selected 10 OPLL cases with medical image processing software (MIMICS®) which create 3D model with Digital Imaging and Communication in Medicine (DICOM) data from CT images after brief explanation was given to examiners before the image construction steps. To assess the reliability of inter- and intra-examiner intraclass correlation coefficient (ICC), 3 examiners measured 4 parameters (volume, length, width, and length) in 10 cases 2 times with 1-week interval. RESULTS: The inter-examiner ICCs among 3 examiners were 0.996 (95% confidence interval [CI], 0.987–0.999) for volume measurement, 0.973 (95% CI, 0.907–0.978) for thickness, 0.969 (95% CI, 0.895–0.993) for width, and 0.995 (95% CI, 0.983–0.999) for length. The intra-examiner ICCs were 0.994 (range, 0.991–0.996) for volume, 0.996 (range, 0.944–0.998) for length, 0.930 (range, 0.873–0.947) for width, and 0.987 (range, 0.985–0.995) for length. CONCLUSION: The medical image processing software (MIMICS®) provided detailed quantification OPLL volume with minimal error of inter- and intra-observer reliability in the measurement of OPLL.

Correlation between Preoperative Magnetic Resonance Imaging Signal Intensity Changes and Clinical Outcomes in Patients Surgically Treated for Cervical Myeloradiculopathy

STUDY DESIGN: This was a single surgeon, single center-based retrospective study with prospective data collection. PURPOSE: To assess the correlation between T2-weighted magnetic resonance imaging (MRI) signal intensity (SI) changes and factors such as age, duration of symptoms, baseline modified Japanese Orthopedic Association (mJOA) score and to determine its prognostic value in predicting recovery after surgery. OVERVIEW OF LITERATURE: Whether intramedullary cord T2-weighted MRI SI changes can predict operative outcomes of cervical myeloradiculopathy remains debatable, with only a few prospective studies analyzing the same. METHODS: Forty-six consecutive patients who underwent cervical myeloradiculopathy were included and were followed up for an average of 1 year. Preoperative T2-weighted MRI SI grading was performed for all patients. The correlation between MRI SI changes and age, duration of symptoms, preoperative mJOA score, and mJOA score at 1-year follow-up were analyzed. RESULTS: Fifteen patients had single-level (21.73%) or double-level (10.86%) prolapsed discs; 54.34% had degenerative cervical spondylosis with canal stenosis or multilevel disc prolapse and 13.07% had ossified posterior longitudinal ligaments. The mean age was 56.17±9.53 years (range, 35–81 years). The mean baseline mJOA score was 10.83±2.58 (range, 6–16), which postoperatively improved to 13.59±2.28 (range, 8–17; p<0.001). There was a statistically significant correlation between mJOA score at 1 year and MRI T2 SI grading (p=0.017). CONCLUSIONS: Patients with longer symptom durations had high grades of intramedullary cord T2-weighted MRI SI changes. Age and preoperative neurological status were not significantly correlated with the existence of intramedullary cord SI changes. However, patients without or with mild and diffuse intramedullary cord T2-weighted MRI SI changes had better postoperative neurological recovery than those with sharp and focal SI changes.

The Relationship between Superior Disc-Endplate Complex Injury and Correction Loss in Young Adult Patients with Thoracolumbar Stable Burst Fracture

BACKGROUND: To determine the relationship between superior disc-endplate complex injury and correction loss after surgery in a group of young adult patients with a stable thoracolumbar burst fracture. METHODS: The study group was comprised of young adult patients who had undergone short-segment posterior fixation and bone grafting under the diagnosis of a stable thoracolumbar burst fracture from March 2008 to February 2014. Follow-up was available for more than 1 year. Before surgery, magnetic resonance imaging was performed to determine injury to the anterior longitudinal ligament, posterior longitudinal ligament, and superior and inferior intervertebral discs and endplates. Correction loss was evaluated by the Cobb angle, intervertebral disc height, upper intervertebral disc angle, vertebral wedge angle, and vertebral body height. RESULTS: No significant relation was noted between correction loss and an injury to the anterior longitudinal ligament, posterior longitudinal ligament, inferior intervertebral disc/endplate, and fracture site, whereas an injury to the superior endplate alone and superior disc-endplate complex showed a significant association. Specifically, a superior intervertebral disc-endplate complex injury showed statistically significant relation to postoperative changes in Cobb angle (p = 0.026) and vertebral wedge angle (p = 0.047). CONCLUSIONS: A superior intervertebral disc-endplate complex injury may have an influence on the prognosis after short-segment fixation in young adult patients with a stable thoracolumbar burst fracture.