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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 mm 3 preoperatively and 1,705 mm 3 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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

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., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

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., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

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 mm 3 in the first examination and 2201.0 ± 1524.1 mm 3 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 (β = -0.48; p = 0.001), body weight (BW) (β = 0.36; p = 0.02), and body mass index (BMI) (β = 0.35; p = 0.03). Furthermore, age was the only significant predictor of OPLL progression (R 2  = 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.

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.

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.

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.