Three-dimensional morphological changes in ossification of the posterior longitudinal ligament of the thoracic spine following posterior decompression and fusion surgery.

BACKGROUND: Using three-dimensional image analysis, we previously reported suppression of ossification progression following posterior fusion surgery for cervical ossification of the posterior longitudinal ligament (OPLL). Here, we aimed to evaluate the morphological changes in thoracic OPLL using three-dimensional analysis. METHODS: Seventeen patients (eight males and nine females; mean age, 56.9 years) who underwent posterior decompression and fusion (PDF) for thoracic OPLL were included. We evaluated the OPLL volume using a novel analysis involving creating a three-dimensional model from computed tomography images to measure the volume accurately. Additionally, OPLL thickness, width, and length were measured on sagittal and axial computed tomography planes. We investigated the morphological changes in OPLL after PDF. Furthermore, patients were classified into reduced volume and increased volume groups and associated factors were compared. RESULTS: The mean OPLL volume was 1,677 mm3 preoperatively and 1,705 mm3 at the final examination and did not significantly differ. Volume reduction was observed in 7 of 17 cases (41 %). Although OPLL width and length significantly increased postoperatively, OPLL thickness significantly reduced from 7.1 mm preoperatively to 6.5 mm postoperatively (all, p < 0.05). The annual thickness changes significantly differed (p <0.05) in the reduced volume group (-0.36 mm/year) compared to that in the increased volume group (-0.06 mm/year). CONCLUSIONS: Thoracic OPLL after PDF becomes thinner in the anteroposterior direction but increases horizontally and craniocaudally. The reduction in OPLL thickness was related to a reduction in ossification volume. We believe that volume reduction in thoracic OPLL is influenced by pulsation of the dural sac.

Predictive biomarkers of ossification progression and bone metabolism dynamics in patients with cervical ossification of the posterior longitudinal ligament.

PURPOSE: This study aimed to establish biomarkers to predict the progression of ossification by examining ossification volume and bone metabolism dynamics in patients with ossification of the posterior longitudinal ligament (OPLL). METHODS: We assessed OPLL progression using computed tomography-based three-dimensional (3D) image analysis and examined bone metabolism dynamics in 107 patients with OPLL (men, 72; women, 35; mean age, 63.6 years). The volume of OPLL was calculated twice during the follow-up period, and OPLL progression was evaluated by the annual rate of ossification increase. Bone metabolism dynamics were assessed by routine blood tests and analysis of various serum biomarkers (including 25-hydroxyvitamin D, intact parathyroid hormone, fibroblast growth factor 23, intact N-terminal propeptide of type 1, tartrate-resistant acid phosphatase isoform 5b, sclerostin, and Dickkopf-1) and bone mineral density (BMD). Patients were classified into the progression (P) or non-progression (NP) group according to the annual rate of increase in previous 3D image analyses, and associated factors between these groups were compared. RESULTS: The P and NP groups consisted of 29 patients (23 men and 6 women) and 78 patients (49 men and 29 women), respectively. Univariate analysis revealed significant differences in terms of age, body mass index, serum phosphorus, serum sclerostin, and BMD. In multivariate analysis, age, serum phosphorus, and serum sclerostin were identified as independent factors associated with OPLL progression. CONCLUSION: Younger age, hypophosphatemia, and high serum sclerostin are risk factors for OPLL progression. Serum phosphorus and sclerostin could serve as important biomarkers for predicting ossification progression.

Cytoskeletal Protein 4.1G Is Essential for the Primary Ciliogenesis and Osteoblast Differentiation in Bone Formation.

The primary cilium is a hair-like immotile organelle with specific membrane receptors, including the receptor of Hedgehog signaling, smoothened. The cilium organized in preosteoblasts promotes differentiation of the cells into osteoblasts (osteoblast differentiation) by mediating Hedgehog signaling to achieve bone formation. Notably, 4.1G is a plasma membrane-associated cytoskeletal protein that plays essential roles in various tissues, including the peripheral nervous system, testis, and retina. However, its function in the bone remains unexplored. In this study, we identified 4.1G expression in the bone. We found that, in the 4.1G-knockout mice, calcium deposits and primary cilium formation were suppressed in the trabecular bone, which is preosteoblast-rich region of the newborn tibia, indicating that 4.1G is a prerequisite for osteoblast differentiation by organizing the primary cilia in preosteoblasts. Next, we found that the primary cilium was elongated in the differentiating mouse preosteoblast cell line MC3T3-E1, whereas the knockdown of 4.1G suppressed its elongation. Moreover, 4.1G-knockdown suppressed the induction of the cilia-mediated Hedgehog signaling and subsequent osteoblast differentiation. These results demonstrate a new regulatory mechanism of 4.1G in bone formation that promotes the primary ciliogenesis in the differentiating preosteoblasts and induction of cilia-mediated osteoblast differentiation, resulting in bone formation at the newborn stage.

Detailed features and prognostic factors of twenty-three patients with drop finger caused by cervical radiculopathy: a retrospective multicentre study.

PURPOSE: It has been reported that C7 and C8 nerve root impairment can cause drop finger; however, the clinical characteristics of each injured nerve root and post-operative outcomes remain unclear. This study aimed to investigate the detailed features and surgery-related prognostic factors of drop finger caused by cervical radiculopathy. METHODS: We retrospectively investigated the clinical characteristics, paralysis patterns and surgery-related prognostic factors of 23 patients with drop finger caused by cervical radiculopathy who underwent posterior cervical foraminotomy. We classified paralysis into three patterns based on the fingers predominantly exhibiting extensor digitorum communis (EDC) muscle weakness: index finger side-dominant, middle and ring fingers-dominant and little finger side-dominant. RESULTS: The aetiologies were cervical disc hernia (CDH) in ten patients, cervical spondylotic radiculopathy (CSR) in eight and both CDH and CSR in five. The levels of the decompressed root were C7 in one patient, C8 in 11 and both C7 and C8 in 11. Scapular pain was frequently observed as the initial symptom (78%), especially in patients with only C8 nerve root disorder (91%). Drop finger recovered to a score of ≥ 3 on manual muscle testing in 17 patients; patients with the little finger side-dominant pattern tended to have poor recoveries. Patients with CDH improved significantly than those with CSR or both CDH and CSR (p < 0.05). CONCLUSIONS: Good surgical recovery of drop finger can be expected in patients with CDH and in those with index fingers-dominant and middle and ring fingers-dominant patterns.

Short- versus long-segment posterior spinal fusion with vertebroplasty for osteoporotic vertebral collapse with neurological impairment in thoracolumbar spine: a multicenter study.

BACKGROUND: Vertebroplasty with posterior spinal fusion (VP + PSF) is one of the most widely accepted surgical techniques for treating osteoporotic vertebral collapse (OVC). Nevertheless, the effect of the extent of fusion on surgical outcomes remains to be established. This study aimed to evaluate the surgical outcomes of short- versus long-segment VP + PSF for OVC with neurological impairment in thoracolumbar spine. METHODS: We retrospectively collected data from 133 patients (median age, 77 years; 42 men and 91 women) from 27 university hospitals and their affiliated hospitals. We divided patients into two groups: a short-segment fusion group (S group) with 2- or 3-segment fusion (87 patients) and a long-segment fusion group (L group) with 4- through 6-segment fusion (46 patients). Surgical invasion, clinical outcomes, local kyphosis angle (LKA), and complications were evaluated. RESULTS: No significant differences between the two groups were observed in terms of neurological recovery, pain scale scores, and complications. Surgical time was shorter and blood loss was less in the S group, whereas LKA at the final follow-up and correction loss were superior in the L group. CONCLUSION: Although less invasiveness and validity of pain and neurological relief are secured by short-segment VP + PSF, surgeons should be cautious regarding correction loss.

Impact of L4/5 Posterior Interbody Fusion With or Without Decompression on Spinopelvic Alignment and Health-related Quality-of-Life Outcomes.

STUDY DESIGN: This was a retrospective case control study. OBJECTIVE: The objective was to determine the impact of single-level interbody fusion at L4/5 with or without concomitant decompression on various spinopelvic parameters and health-related quality-of-life (HRQOL) outcomes. SUMMARY OF BACKGROUND DATA: Recently, focus has swayed from a regional concern to a global sagittal alignment, more comprehensive approach in multilevel, corrective fusion for adult spinal deformity. However, only a few comprehensive studies have investigated the relationships between the various related spinopelvic parameters and HRQOL outcomes using single-level interbody fusion. MATERIALS AND METHODS: In total, 119 patients with lumbar degenerative disorders (mean age, 68 y; 38 males and 81 females) who underwent L4/5 single-level posterior interbody fusion with a minimum 2-year follow-up were included. Participants were divided into 2 groups according to preoperative sagittal modifiers of the SRS-Schwab adult spinal deformity classification. The correlation between spinopelvic parameters and HRQOL outcomes was investigated. Negative or positive values indicated lordosis. HRQOL outcomes were assessed using visual analog scale scores, Japanese Orthopedic Association Back Pain Evaluation Questionnaires (JOABPEQ), and short form-36 (SF-36). RESULTS: L4/5 local lordosis increased from 6.4±4.4 degrees preoperatively to 11.3±4.5 degrees at 2 years postoperatively (P<0.0001). Further analysis of the results also showed a correlation between change in L4/5 local lordosis and change in lumbar lordosis (LL) (rs=0.229, P=0.0143). The high pelvic incidence-LL (≥20 degrees, n=28) and high sagittal vertical axis groups (≥5 cm, n=29) had lower scores in walking ability, social life domains of JOABPEQ, and physical component summary scores of SF-36 preoperatively, and 2 years postoperatively. Fusion status did not affect the HRQOL outcomes, except that concomitant decompression at the adjacent disk level yielded lower SF-36 physical component summary scores 2 years postoperatively. CONCLUSIONS: Improvement in L4/5 local lordosis possibly triggers a simultaneous sequence of change in total LL after posterior single-level fusion. HRQOL outcomes were negatively affected by both preoperative and postoperative pelvic incidence-LL mismatch and global sagittal malalignment. LEVEL OF EVIDENCE: Level III.

Three-dimensional morphological analysis of cervical foraminal stenosis using dynamic flexion-extension computed tomography images.

BACKGROUND: Morphological features of foraminal stenosis in cervical spondylotic radiculopathy and the adequate extent of facet resection in posterior cervical foraminotomy remain uncertain. Herein, we evaluated quantitatively foraminal widths in cervical spondylotic radiculopathy on dynamic flexion-extension computed tomography using a novel three-dimensional analysis method and determined the extent of facet resection in posterior cervical foraminotomy. METHODS: Seventeen patients undergoing posterior cervical foraminotomy for cervical spondylotic radiculopathy were evaluated. A neuroforamen three-dimensional model was built from preoperative images of flexion-extension computed tomography myelography, and an ordinary cervical spine coordinate system and an original neuroforaminal coordinate system, were established. In the neuroforaminal coordinate system, minimum areas perpendicular to the long axis by the slices from inlet to outlet of neuroforamen and narrowest foraminal width in a slice of minimum area were measured. The location of the narrowest region from inlet of the foramen was calculated. Ratios of minimum and sufficient facet resection were obtained from the location of the narrowest region in the neuroforaminal coordinate system. RESULTS: The narrowest foraminal widths (flexion/extension) in the cervical spine coordinate system and the neuroforaminal coordinate system were 2.9/2.3 and 2.6/1.9 mm, respectively. The mean values of the location of the narrowest region (flexion/extension) were 0.27/0.22 and 0.50/0.45 mm, respectively, and the narrowest region in the neuroforaminal coordinate system was located on the outer side than in the cervical spine coordinate system (p < 0.001). The ratios of minimum and sufficient facet resection were 23 ± 8% and 32 ± 9%, respectively. CONCLUSIONS: The narrowest regions both in flexion and extension are located at the middle of the foramen based on the neuroforaminal coordinate system. Ordinary evaluation of axial computed tomography images likely underestimates the extent of facet resection, whereas certain extent of facet resection does not exceed 50% in cases with single-level cervical spondylotic radiculopathy. STUDY DESIGN: A retrospective case control study.

Risk Factors for Proximal Junctional Fracture Following Fusion Surgery for Osteoporotic Vertebral Collapse with Delayed Neurological Deficits: A Retrospective Cohort Study of 403 Patients.

INTRODUCTION: Approximately 3% of osteoporotic vertebral fractures develop osteoporotic vertebral collapse (OVC) with neurological deficits, and such patients are recommended to be treated surgically. However, a proximal junctional fracture (PJFr) following surgery for OVC can be a serious concern. Therefore, the aim of this study is to identify the incidence and risk factors of PJFr following fusion surgery for OVC. METHODS: This study retrospectively analyzed registry data collected from facilities belonging to the Japan Association of Spine Surgeons with Ambition (JASA) in 2016. We retrospectively analyzed 403 patients who suffered neurological deficits due to OVC below T10 and underwent corrective surgery; only those followed up for　≥2 years were included. Potential risk factors related to the PJFr and their cut-off values were calculated using multivariate logistic regression analysis and receiver operating characteristic (ROC) analysis. RESULTS: Sixty-three patients (15.6%) suffered PJFr during the follow-up (mean 45.7 months). In multivariate analysis, the grade of osteoporosis (grade 2, 3: adjusted odds ratio (aOR) 2.92; p=0.001) and lower instrumented vertebra (LIV) level (sacrum: aOR 6.75; p=0.003) were independent factors. ROC analysis demonstrated that lumbar bone mineral density (BMD) was a predictive factor (area under curve: 0.72, p=0.035) with optimal cut-off value of 0.61 g/cm2 (sensitivity, 76.5%; specificity, 58.3%), but that of the hip was not (p=0.228). CONCLUSIONS: PJFr was found in 16% cases within 4 years after surgery; independent risk factors were severe osteoporosis and extended fusion to the sacrum. The lumbar BMD with cut-off value 0.61 g/cm2 may potentially predict PJFr. Our findings can help surgeons select perioperative adjuvant therapy, as well as a surgical strategy to prevent PJFr following surgery.

Quantitative radiographic analysis of foraminal re-stenosis after posterior cervical foraminotomy with laminoplasty.

Few studies have performed detailed radiographic evaluation of the cause of recurrent cervical radiculopathy. In this study, we aimed to perform quantitative analyses of foraminal re-stenosis after posterior cervical foraminotomy (PCF) concomitant with laminoplasty. Seventy-eight consecutive patients (50 males and 28 females, mean age of 62 years at surgery) with cervical spondylotic radiculomyelopathy who underwent PCF concomitant with open-door laminoplasty were included. A total of 133 foramina undergoing PCF were radiographically evaluated using the following parameters: disc height, focal range of motion at the corresponding disc level, foraminal diameter (FD) and facet joint width (FJW) in the axial view on computed tomography, and re-stenosis rate (RR) of foramina. RR was calculated as follows: (foraminal regrowth at 2 years after surgery)/(foraminal enlargement immediate postoperatively) × 100% (RR2y). FDs preoperatively, postoperatively, and at 2-year follow-up were 2.2, 6.6, and 4.6 mm, respectively, and FJWs were 14.5, 9.0, and 10.6 mm, respectively. Both parameters significantly increased at the 2-year follow-up (p < 0.001). The mean RR2y was 42% (range, -16 to 108%). On logistic regression analysis of risk factors for higher RR2y (>50%), only preoperative posterior disc height (PDH) (OR = 0.33; 95% CI = 0.193-0.563; p < 0.001) was identified. Receiver operating characteristic curve analysis showed that the cut-off value of RR2y 50% was 1-mm PDH (AUC 0.73, sensitivity 52%, specificity 86%, p value < 0.001). After posterior foraminotomy with laminoplasty, the enlarged foraminal space gradually decreased during the 2-year follow-up. Foraminal re-stenosis was mainly due to bone regrowth of the resected facet joint, which is caused by disc degeneration with loss of PDH.

Surgical outcomes of spinal fusion for osteoporotic thoracolumbar vertebral fractures in patients with Parkinson's disease: what is the impact of Parkinson's disease on surgical outcome?

BACKGROUND: To date, there have been little published data on surgical outcomes for patients with PD with thoracolumbar OVF. We conducted a retrospective multicenter study of registry data to investigate the outcomes of fusion surgery for patients with Parkinson's disease (PD) with osteoporotic vertebral fracture (OVF) in the thoracolumbar junction. METHODS: Retrospectively registered data were collected from 27 universities and their affiliated hospitals in Japan. In total, 26 patients with PD (mean age, 76 years; 3 men and 23 women) with thoracolumbar OVF who underwent spinal fusion with a minimum of 2 years of follow-up were included (PD group). Surgical invasion, perioperative complications, radiographic sagittal alignment, mechanical failure (MF) related to instrumentation, and clinical outcomes were evaluated. A control group of 296 non-PD patients (non-PD group) matched for age, sex, distribution of surgical procedures, number of fused segments, and follow-up period were used for comparison. RESULTS: The PD group showed higher rates of perioperative complications (p < 0.01) and frequency of delirium than the non-PD group (p < 0.01). There were no significant differences in the degree of kyphosis correction, frequency of MF, visual analog scale of the symptoms, and improvement according to the Japanese Orthopaedic Association scoring system between the two groups. However, the PD group showed a higher proportion of non-ambulators and dependent ambulators with walkers at the final follow-up (p < 0.01). CONCLUSIONS: A similar surgical strategy can be applicable to patients with PD with OVF in the thoracolumbar junction. However, physicians should pay extra attention to intensive perioperative care to prevent various adverse events and implement a rehabilitation regimen to regain walking ability.

Perioperative factors associated with favorable outcomes of posterior decompression and instrumented fusion for cervical ossification of the posterior longitudinal ligament: A retrospective multicenter study.

PURPOSE: Posterior decompression with instrumented fusion (PDF) is a suitable surgical treatment for K-line (-)-type cervical ossification of the posterior longitudinal ligament (OPLL). However, the adequate indications of PDF have not been clarified yet. The purpose of this study was to investigate the surgical results of PDF and perioperative factors that influence the surgical outcome, and to clarify the adequate indications of PDF. METHODS: Twenty-seven patients (21 men and 6 women, mean age: 61.4 years) who were diagnosed with a K-line (-)-type OPLL that was treated with PDF were included in this study. We evaluated these patients clinically and radiologically to investigate the outcomes of PDF and perioperative factors that influence improvements in the Japanese Orthopedic Association (JOA) score. RESULTS: The mean recovery rate of JOA score at the final follow-up examination was 53.3%. In the statistical analysis, the preoperative C2-C7 angle and the C2-C7 angle immediately postoperatively significantly predicted the surgical outcome. The C2-C7 angle immediately postoperatively was the only most important predictor. Using a receiver operating characteristic curve analysis, we found that the cutoff value of the C2-C7 angle immediately postoperatively for good outcomes (recovery rate of JOA score ≥50%) was -2.0°. CONCLUSIONS: PDF for K-line (-)-type OPLL patients with preoperative lordotic alignment can be expected to have favorable outcomes, which is the adequate indication for PDF. Since the C2-C7 angle immediately postoperatively was the most important predictor, the physician should pay attention to maintain the cervical lordotic alignment to enhance the surgical outcomes in surgical planning.

Natural history of the ossification of cervical posterior longitudinal ligament: a three dimensional analysis.

PURPOSE: Three-dimensional (3D) imaging using computed tomography (CT) has made it possible to accurately evaluate ossification of the posterior longitudinal ligament (OPLL). Recently, we developed a novel technique to measure ossification volume using the 3D analysis. The purpose of this study was to investigate the natural course of OPLL and the risk factors for volume progression. METHODS: Forty-one patients (22 males and 19 females) diagnosed with cervical OPLL who had been non-surgically treated were included in this study. We evaluated clinical examination, radiological findings, and the volume of ossified lesions during at least 1-year intervals. Furthermore, we performed risk factor analysis for OPLL volume progression. RESULTS: The mean ossification volume was 2047.4 ± 1437.3 mm3 in the first examination and 2201.0 ± 1524.1 mm3 in the final examination, indicating a significant increase during the follow-up period (p < 0.001). The mean annual rate of lesion increase was 4.1 ± 2.7%. Univariate regression analysis demonstrated significant relationships between the annual rate of lesion increase and age (ß = -0.48; p = 0.001), body weight (BW) (ß = 0.36; p = 0.02), and body mass index (BMI) (ß = 0.35; p = 0.03). Furthermore, age was the only significant predictor of OPLL progression (R2 = 0.23; p = 0.001) in multivariate liner regression analysis. CONCLUSIONS: Younger age, higher BW, and higher BMI are predictors of OPLL progression. Younger age is the most significant predictor in non-surgically treated patients.

Surgical Outcomes of Posterior Spinal Fusion Alone Using Cervical Pedicle Screw Constructs for Cervical Disorders Associated With Athetoid Cerebral Palsy.

STUDY DESIGN: Retrospective case series. OBJECTIVE: The aim of this study was to investigate clinical outcomes after posterior spinal fusion (PSF) using cervical pedicle screw (CPS) constructs for cervical disorders associated with athetoid cerebral palsy (CP). SUMMARY OF BACKGROUND DATA: Traditionally, most patients with cervical myelopathy associated with CP have required combined anterior and posterior fusion to achieve solid stability against severe involuntary movement. METHODS: Thirty-one CP patients with cervical disorders who underwent PSF alone with a minimum 2-year follow-up (mean 58 months) were analyzed. All patients were treated with PSF using CPS constructs with or without decompression procedures. The average number of fused segments was 5.1 (range, 1-10 segments), and a halo jacket was applied in 16 patients for at least 2 months after surgery. Clinical outcomes using the Japanese Orthoedic Association scoring system (JOA score) and walking ability, radiographic sagittal alignment, fusion status, and surgery-related complications were evaluated. RESULTS: The JOA score improved from 8.3 points preoperatively to 10.9 points at the final follow-up (P < 0.05). Although no patients experienced deterioration in their walking ability postoperatively, 10 patients were unable to walk at the final follow-up. Sagittal alignment, including C0-2 angle, C2-7 angle, and local alignment in fused segments, was maintained postoperatively. Twenty-five patients achieved fusion at the final follow-up (fusion rate: 81%), and fivepatients with nonunion required additional surgery. With regard to complications, 5 patients encountered postoperative upper extremity palsy. CONCLUSION: The CPS construct is amenable to achieve a relatively high fusion rate without correction loss, and good clinical outcomes can be achieved with a posterior single approach for CP patients. In the future, efforts should be made to make appropriate decisions regarding the fusion area, take preventative measures against postoperative upper extremity palsy, and simplify external orthoses after surgery, especially with the use of a halo jacket. LEVEL OF EVIDENCE: 4.

Posterior instrumented fusion suppresses the progression of ossification of the posterior longitudinal ligament: a comparison of laminoplasty with and without instrumented fusion by three-dimensional analysis.

PURPOSE: There is no definitive evidence that additional instrumented fusion following laminoplasty suppresses the progression of ossification of the posterior longitudinal ligament (OPLL). Recently, we reported a novel method involving the creation of three-dimensional (3D) model from computed tomography images to measure the volume of OPLL accurately. The study aim was to evaluate whether laminoplasty with instrumented fusion suppresses the progression of OPLL in comparison with stand-alone laminoplasty by our novel 3D analysis. METHODS: The present study comprised of a group of 19 patients (14 men, five women) with OPLL treated with posterior decompression and fusion (PDF group), and a group of 22 patients (14 men, eight women) treated with laminoplasty alone (LP group). The volume of OPLL was evaluated three times during the follow-up period, and the volume change of OPLL was compared between the two groups. RESULTS: The PDF group (2.0 ± 1.7 %/year; range, -3.0 to 5.3) demonstrated lower annual rate of lesion increase compared to the LP group (7.5 ± 5.6 %/year; range, 1.0-19.2) (p < 0.001). In a notable thing, the annual rate of increase from the 2nd to the 3rd measurement significantly decreased compared with that from the 1st to the 2nd measurement in the PDF group (p < 0.05). CONCLUSION: This is the first study to prove a possible suppressant effect of additional posterior instrumented fusion on OPLL progression using novel 3D analysis.

New classification system for ossification of the posterior longitudinal ligament using CT images.

BACKGROUND: Ossification of the posterior longitudinal ligament (OPLL) is most frequently seen in the cervical spine. The types of cervical OPLL are classified into continuous, mixed, segmental, and other based on plain lateral X-ray. Computed tomography (CT) imaging is often used in clinical practice for evaluating ossified lesions as it can detect their precise location, size, and shape. However, to date, no CT classification of OPLL lesions has been proposed. METHODS: One hundred and forty-four patients diagnosed with cervical OPLL by plain radiograph were included in this study. Sagittal and axial CT images of the cervical spine were obtained. We propose three classification systems: A, B, and axial. Classification A comprises two lesion types: bridge and nonbridge. Classification B requires examiners to describe all vertebral and intervertebral levels where OPLL exits in the cervical spine. Axial classification comprises central and lateral lesions identified on axial CT images. Seven observers evaluated CT images using this classification system, and intra- and interrater reliability were examined. RESULTS: Averaged Fleiss' kappa coefficient of interrater agreement was 0.43 ± 0.26 among the seven observers, averaged intrarater reliability for the existence of OPLL was 72.4 ± 8.8% [95% confidence interval (CI) 67.5-76.8]. Fifty-four patients (37.5%) had the bridge type and 90 the nonbridge type according to Classification A; 102 (70.8%) had central and 42 (29.2%) lateral OPLL in the axial classification. Four representative cases defined according to the three classification types are reported here. CONCLUSION: Subcommittee members of the Investigation Committee on the Ossification of the Spinal Ligaments of the Japanese Ministry of Public Health and Welfare propose three new classification systems of cervical OPLL based on CT imaging: A, B, and axial.

Three-dimensional evaluation of volume change in ossification of the posterior longitudinal ligament of the cervical spine using computed tomography.

BACKGROUND: Two-dimensional imaging is not adequate for evaluating ossification of the posterior longitudinal ligament (OPLL). This study was designed to evaluate the accuracy of a novel computed tomography (CT)-based three-dimensional (3D) analysis method that we had devised to measure volume changes in OPLL. SUBJECTS AND METHODS: Twenty OPLL patients (12 male and 8 female; mean age 63.6 years) who were being followed conservatively were examined twice with an interval of at least 1 year between the two scans. The mean interval was 22 (range 12-45) months. A 3D model was created with DICOM data from CT images, using the MIMICS(®) software to calculate the volume. The mean ossification volume was determined from two measurements. Since ossification size varies widely, evaluation of change in volume is generally affected by the original size. Therefore, the change in ossification volume between the first and second CT examinations was calculated as the annual rate of progression. RESULTS: The type of OPLL was classified as continuous in 3 patients, segmented in 3, and mixed in 14. The mean ossification volume was 1,831.68 mm(3) at the first examination and 1,928.31 mm(3) at the second, showing a significant mean increase in ossification volume. The mean annual rate of lesion increase was 3.33% (range 0.08-7.79%). CONCLUSION: The 3D method used allowed detailed OPLL classification and quantification of change in the ossified volume. Thus, this method appears to be very useful for quantitative evaluation of OPLL with only minimal measurement error.

Preoperative evaluation of the vertebral arteries and posterior portion of the circle of Willis for cervical spine surgery using 3-dimensional computed tomography angiography.

STUDY DESIGN: A retrospective analysis using prospectively collected data from 3-dimensional computed tomography angiography (3D-CTA). OBJECTIVE: To investigate the frequency of anomalous vertebral arteries (VA) and variations of the posterior portion of the circle of Willis (PPCW) using 3D-CTA for preventing perioperative iatrogenic vascular complications. SUMMARY OF BACKGROUND DATA: Some studies have reported that preoperative 3D-CTA is useful for determining the VA blood flow in the cervical spine. However, preoperative 3D-CTA has not been used for evaluating PPCW, which functions as vessels collateral to the basilar artery in the case of iatrogenic VA injury. METHODS: The study included 100 consecutive patients (61 males and 39 females; mean age, 60.4 ± 15.4 yr; range, 11-86 yr) who underwent cervical decompression and/or instrumentation between April 2008 and May 2012. We measured the diameters of the VA (VAD), posterior communicating artery (PCOMD), first segment of the posterior cerebral artery (P1D), and basilar artery (BAD) twice and determined the frequency of anomalous VA and PPCW variations. RESULTS: Hypoplastic VA, hypoplastic PCOM, and hypoplastic P1 were detected in 11 (11.0%), 81 (81.0%), and 13 patients (13.0%), respectively. Hypoplastic PCOM-P1 and hypoplastic basilar artery were observed in 87 (87.0%) and 3 patients (3.0%), respectively. Overall, 47 patients (47.0%) possessed some degree of abnormal VA blood flow.There were 7 patients (7.0%) with both unilaterally hypoplastic VA and bilaterally hypoplastic PCOM-P1s, in whom iatrogenic VA injury on the dominant side could have caused lethal vascular complications. We termed the hypoplastic VA of the contralateral side without collateral vessels as "critical VA." CONCLUSION: The VAs and PPCW vary considerably. Preoperative 3D-CTA provides important information for preventing tragic vascular complications caused by iatrogenic VA injury. Taking the risk of radiation into consideration, we recommend this method for patients at the highest risk for iatrogenic VA injury.

Descending aortic injury by a thoracic pedicle screw during posterior reconstructive surgery: a case report.

STUDY DESIGN: Case report. OBJECTIVE: To describe an iatrogenic aortic injury by pedicle screw instrumentation during posterior reconstructive surgery of spinal deformity. SUMMARY OF BACKGROUND DATA: Iatrogenic major vascular injuries during anterior instrumentation procedures have been reported by several authors, but there have been few reports regarding iatrogenic major vascular injuries during posterior instrumentation procedures. METHODS: A 57-year-old woman with thoracolumbar kyphosis due to osteoporotic T12 vertebral fracture underwent posterior correction and fusion (T10-L2), using segmental pedicle screw construct concomitant with T12 pedicle subtraction osteotomy. Postoperative routine plain radiographs and computed tomography myelography demonstrated a misplaced left T10 pedicle screw, which was in contact with the posteromedial aspect of the thoracic aorta, and suspected penetration of the aortic wall. The patient underwent removal of the pedicle screw, and repair of the penetrated aortic wall through a simultaneous anterior-posterior approach. RESULT: The patient tolerated the procedure well without neurologic sequelae, and was discharged several days after removal of a left tube thoracostomy. Plain radiographs demonstrated solid fusion at the osteotomy site and no loosening of hardware. Preoperative neurologic symptoms improved completely at 18-months follow-up. CONCLUSION: Use of pedicle screw instrumentation has the potential to cause major vascular injury during posterior spinal surgery, and measures to prevent this complication must be taken. Timely diagnosis and treatment are essential to prevent both early and delayed complications and death.

Molecular analyses of cell origin and detection of circulating tumor cells in the peripheral blood in alveolar soft part sarcoma.

Alveolar soft part sarcoma (ASPS) is a distinct, rare soft tissue tumor with an unknown histogenesis and a tendency for late widespread metastases to lung, bone, and brain. It is now clear that they are caused by a specific unbalanced translocation, der(17)t(X;17)(p11;q25), which results in the formation of an ASPSCR1-TFE3 (alias ASPL-TFE3) fusion gene. The rearrangement results in the expression of chimeric transcripts, which can be identified by means of reverse transcriptase-polymerase chain reaction (RT-PCR). We investigated the histogenesis of ASPS and attempted to detect circulating ASPS tumor cells in peripheral blood. The immunohistochemical and genetic details of four cases and one cell line of ASPS were examined. An immunohistochemical analysis and RT-PCR did not detect myogenic differentiation gene MYOD1. The sensitivity of nested RT-PCR for detection of circulating ASPS cells was assessed by demonstrating that the tumor cell-associated gene translocation could be detected in 50 tumor cells/2 mL of blood. Clinically, it was detectable in a peripheral blood sample (2 mL) of ASPS patient with distant metastases. The findings suggest that ASPS is not of skeletal muscle origin. ASPS tumor cells in the peripheral blood could be monitored by RT-PCR.

The role of glucan-binding proteins in the cariogenicity of Streptococcus mutans.

Streptococcus mutans produces glucan-binding proteins (Gbps), which appear to contribute to the virulence of S. mutans. GbpA and GbpC genes were inactivated by the insertion of antibiotic-resistant genes into each gbp gene of S. mutans MT8148 to generate Gbp-defective mutants. Sucrose dependent adherences of the GbpA- and GbpC-defective mutants were found to be significantly lower than those of their parent strains MT8148. Caries inducing activity of the mutants in rats was significantly lower than that of strain MT8148R (streptomycin-resistant strain of MT8148). These results suggest that GbpA and GbpC participate in cellular adherence to tooth surfaces and contribute to the cariogenicity of S. mutans.