Ossification Of The Posterior Longitudinal Ligament Thickness Research Articles

Importance of gap evaluation in the ossification of posterior longitudinal ligament lesions using 3-dimensional computed tomography

BACKGROUND CONTEXTEvaluating the gaps within the ossification of the posterior longitudinal ligament (OPLL) lesions, which may contribute to neurological symptoms, using conventional imaging techniques is challenging. OBJECTIVEThis study aimed to investigate the importance of evaluating gaps using 3-dimensional computed tomography (3D-CT) and their association with the occurrence of magnetic resonance imaging (MRI) T2 high intensity in the spinal cord. STUDY DESIGN/SETTINGRetrospective cohort study. PATIENT SAMPLERetrospective analysis of 116 patients diagnosed with cervical OPLL. OUTCOME MEASURESPresence of gaps in OPLL, presence of T2 high intensity in the cervical spinal cord, and OPLL thickness were evaluated. METHODSLateral X-ray, CT, and reconstructed 3D-CT images were reviewed to assess lesion characteristics and the presence of gaps. MRI was used to evaluate the change in spinal cord signal intensity. The relationship among gap presence, lesion morphology, and MRI T2 high intensity in the spinal cord was examined. RESULTSA significant difference in gap detection accuracy was observed between CT and 3D-CT (p=.0054). CT demonstrated false-positive results in the detection of gaps as compared with 3D-CT. The presence of gaps was significantly associated with an increased likelihood of MRI T2 high intensity in the spinal cord (p=.037). Patients with thicker lesions and smaller space available for the spinal cord (SAC) were more likely to exhibit T2 high intensity. Meanwhile, patients with gaps co-occurring with T2 high intensity exhibited significantly thinner lesions (p=.011) and larger SACs (p=.0002). Patients with gaps had a significantly lower JOA scores (p=.0035), which indicates that patient with gaps are likely to exhibit more severe clinical neurological symptoms. CONCLUSION3D-CT showed superiority in accurately identifying gaps within OPLL lesions, while CT demonstrated false-positive results in the detection of gaps. Furthermore, the gap presence was a risk factor for MRI T2 high intensity in the spinal cord, independent of lesion thickness. In addition, gaps are related to more severe clinical symptoms. This study highlighted the importance of evaluating gaps within OPLL lesions using 3D-CT to clarify neurological pathogenesis.

The R-line: A New Imaging Index for Decision Making Regarding C2 Lamina Decompression in Cervical Ossification of the Posterior Longitudinal Ligament

ObjectiveThe optimal treatment modality for cervical ossification of the posterior longitudinal ligament (OPLL) including the C2 level remains controversial. Cervical laminoplasty is a widely accepted considering of advantages such as development of few postoperative complications, including kyphosis or neck pain. We encountered seven patients with postoperative disabilities resulting from incomplete decompression after undercutting of the C2 lamina. Based on this experience, we developed a new index to determine the degree of decompression in cervical OPLL—the rostral line (R-line).MethodsTotal of 79 consecutive patients who underwent posterior decompression of cervical OPLL were included in this study. Mean age at the time of operation, the C2-C7 cervical lordotic angle and OPLL thickness at the most stenotic level of the spinal canal, and preoperative/postoperative Japanese Orthopedic Association score was checked in these group. We compared the correspondence between the degree of C2 lamina decompression using the R-line and actual degree of decompression.ResultsIn all patients, the R-line touched the upper half of the C2 lamina on preoperative magnetic resonance imaging (MRI). The C2-C3 local segment lordotic angle and maximal degree of spinal cord compression by OPLL were independently correlated to postoperative C2 cord shifting. This result indicates that the R-line is a valid indicator to determine the degree of C2 lamina decompression in OPLL extending to the C2 level.ConclusionThe results showed that undercutting the C2 lamina can result in incomplete spinal cord decompression and poor clinical outcome if the R-line touches the upper half of the C2 lamina on preoperative MRI.

The progression of ossification of the posterior longitudinal ligament of the cervical spine: A follow-up study by CT im-aging after laminoplasty

Objective To evaluate the CT imaging after laminoplasty for the patients with ossification of the posterior lon-gitudinal ligament (OPLL) of the cervical spine. Methods From June 2011 to June 2016, Retrospectively analyzed the data of OPLL patients who underwent posterior cervical open-door laminoplasty. There were 21 patients finally enrolled in this study, which consisted of 11 male and 10 female aging from 55-69, mean(61.48±4.29). The preoperative patients all had severe symp-toms of spinal compression. Collected the Japanese Orthopaedic Association Scores(JOA) Scores of all patients for gender, age, pre-operative and postoperative follow-up.The length, width and thickness of OPLL were measured by CT scan and two-dimensional re-construction of cervical spine during preoperative and follow-up, and the average progress rate was calculated. The relationship be-tween OPLL size before surgery and OPLL progress rate after surgery was analyzed. Results A total of 21 patients were included in this study, with an average age of 61.48±4.29 years-old. The mean follow-up time was 3.36±1.92 years. The JOA score of cervi-cal spine was 11.81±1.75 before operationand 14.43±1.69 at the last follow-up time (t=3.8, P<0.01). The progression rate of OPLL length, width and thickness was 3.54± 2.89 mm/year, 0.49± 0.52 mm/year and 0.34± 0.21 mm/year, respectively. Compared with the width and thickness, the average progress speed of the length was statistically significant (t=3.6, P=0.003; t= 3.8, P=0.002). The progression rate of the rostraland caudal of OPLL was 1.54 ±1.19 mm/year and 1.60±1.33 mm/year (t=0.1, P=0.559). Linear regression showed that OPLL length progression speed (mm)=0.05×preoperative length+1.23, R2=0.26 and P=0.02. Theprogres-sion rate of width and thickness of OPLL had no correlation with preoperative OPLL width and thickness. The progression rates of local, segmental, continuous, and mixed OPLL were 3.02±0.26 mm, 2.97±0.65 mm, 3.65±1.14 mm, and 3.82±1.27 mm per year. Conclusion The JOA score of the posterior open-door laminoplasty of the cervical OPLL patients was significantly improved dur-ing a short-term follow up. CT imaging follow-up showed there was progression of OPLL in length, width and thickness, and the progression rate of length was faster than width and thickness. However, there was no significant difference between the progres-sion of rostral and caudal of OPLL. In addition, short-term follow-up showed a positive correlation between the progression rate of OPLL length and the length of OPLL preoperation.The progress rate of mixed and continuous OPLL may be greater than that of seg-mental and limited OPLL. Key words: Cervical vertebrae; Ossification of posterior longitudinal ligament; Tomography, spiral computed; Follow-up studies

Can K-Line Predict the Clinical Outcome of Anterior Controllable Antedisplacement and Fusion Surgery for Cervical Myelopathy Caused by Multisegmental Ossification of the Posterior Longitudinal Ligament?

To analyze the correlation between the K-line-based classification of patients with ossification of the posterior longitudinal ligament (OPLL) and their outcome after anterior controllable antedisplacement and fusion (ACAF) surgery. A series of 24 patients with multisegmental OPLL were enrolled. All patients underwent ACAF surgery. First, the patients were classified into 2 groups according to their K-line classification. Then, we separated the patients into subgroups according to their OPLL thickness. The Japanese Orthopaedic Association scores before and 6 months after surgery were studied, and the recovery rate (RR) was calculated. The preoperative and postoperative radiologic parameters were also investigated. Clinical and radiographic assessments showed no significant correlation between the K-line-based classification of patients with OPLL and their outcome of ACAF surgery (P > 0.05). When the OPLL was ≤6 mm thick, K-line-based classification groups had a similar change of occupation ratio and RR (P > 0.05). However, when the OPLL was >6 mm thick, the mean RR was 61.8% ± 14.0% in the K-line (+) group and 78.3% ± 9.7% in the K-line (-) group (P < 0.05), and the mean was 16.0% ± 4.2% in the K-line (+) group and 28.0% ± 7.1% in the K-line (-) group (P < 0.05). This study shows that K-line can predict the clinical outcome of ACAF surgery for multisegmental OPLL in a different way from posterior decompression surgery. When the OPLL was thin, the outcome was satisfactory and there was no correlation with K-line-based classification of patients with OPLL. When the OPLL was >6 mm thick, the K-line (-) group patients had a better outcome than did K-line (+) group patients.

Radiological risk factors for progression of ossification of posterior longitudinal ligament following laminoplasty

Background ContextResearch shows the progression of ossification of the posterior longitudinal ligament (OPLL) following decompressive surgery for cervical myelopathy, particularly in cases presenting with continuous or mixed radiographic types. To date, no study has investigated OPLL progression within each motion segment. PurposeTo evaluate progression of cervical OPLL in each motion segment using a novel system of classification, and to identify risk factors for OPLL progression following laminoplasty. Study Design/SettingRetrospective case series. Patient SampleThis study included 34 patients (86 segments) with cervical myelopathy secondary to OPLL. Outcome MeasuresClinical and radiological data (plain radiographs and computed tomography [CT]) were obtained. MethodsClinical data from 34 patients (86 segments) with cervical myelopathy secondary to OPLL were evaluated retrospectively. All subjects had undergone laminoplasty at a single center. Sagittal reconstructive CT images were used to measure OPLL thickness in each segment. Ossified masses were classified into four types according to the degree of disc space involvement: type 1 (no involvement); type 2 (involving disc space but not crossing); type 3 (crossing disc space but not fused); and type 4 (complete bridging). Range of motion (ROM) for each segment was measured using dynamic radiographs. Statistical analyses were performed to determine the degree of OPLL progression according to the four disc space involvement types and ROM. ResultsMean OPLL progression was significantly higher in types 2 (1.3 mm) and 3 (1.5 mm) than in type 1 (0.5 mm) (p<.001). Severe progression (change in thickness >2 mm) was more frequent in types 2 (8 of 29) and 3 (7 of 16) than in types 1 (1 of 35) or 4 (0 of 6) (p=.002). In types 2 or 3, ROM>5° was correlated with severe OPLL progression (52% vs. 8%; p=.035). ConclusionsType 2 or 3 disc involvement and segmental ROM>5° were risk factors for OPLL progression. Classification of cervical OPLL according to disc involvement may help predict OPLL progression following laminoplasty. Close follow-up is warranted in cases of type 2 or 3 with greater segmental motion.

Addition of instrumented fusion after posterior decompression surgery suppresses thickening of ossification of the posterior longitudinal ligament of the cervical spine

Laminoplasty (LMP) is a widely accepted surgical procedure for ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. Progression of OPLL can occur in the long term after LMP. The aim of the present study was to determine whether addition of the instrumented fusion, (posterior decompression with instrumented fusion [PDF]), can suppress progression of OPLL or not. The present study included 50 patients who underwent LMP (n=23) or PDF (n=27) for OPLL of the cervical spine. We performed open door laminoplasty. PDF surgery was performed by double-door laminoplasty followed by instrumented fusion. We observed the non-ossified segment of the OPLL and measured the thickness of the OPLL at the thickest segment with pre- and postoperative sagittal CT multi-planar reconstruction images. Postoperative CT scan revealed fusion of the non-ossified segment of the OPLL was obtained in 4/23 patients (17%) in the LPM group and in 23/27 patients (85%) in the PDF group, showing a significant difference between both groups (p=0.003). Progression of the thickness of the OPLL in the PDF group (−0.1±0.4mm) was significantly smaller than in the LMP group (0.6±0.7mm, p=0.0002). The proportion of patients showing the decrease in thickness of OPLL was significantly larger in the PDF group (6/27 patients; 22%) than in the LMP group (0/23 patients; 0%, p=0.05). In conclusion, PDF surgery can suppress the thickening of OPLL.

Usefulness of 3-dimensional Measurement of Ossification of the Posterior Longitudinal Ligament (OPLL) in Patients With OPLL-induced Myelopathy.

Retrospective study. To evaluate the usefulness of 3-dimensional (3D) measurement of ossification of the posterior longitudinal ligament (OPLL), and identify the reliability of a novel 3D method of measurement. OPLL is not a 2-dimensional (2D) disease, but rather a 3D disease. Therefore, conventional measurement of parameters using radiography may not be suitable for evaluating OPLL. However, there is no study that investigated the correlation between 3D parameters of OPLL and clinical outcomes. 50 patients (40 males and 10 females; mean age 57.2 yr) with symptomatic OPLL were enrolled. Neurological and clinical outcome scales were measured using the Japanese Orthopedic Association (JOA) score, visual analogue scale, short-form health survey (SF-36) and neck disability index. A 3D model was reconstructed with digital imaging and communications in medicine files from axial computed tomographic images using software (MIMICS; Materialise, Leuven, Belgium) to obtain the following parameters: 3D volume of OPLL, 3D volume of the spinal canal (confined to the vertebral level involving OPLL), spinal canal diameter, thickness of OPLL, and length of OPLL. All patients were divided into 2 different groups, the mild myelopathy group (JOA score ≥18, n = 11) and the severe myelopathy group (JOA score ≤17, n = 23). The 3D OPLL volume did not correlate with clinical outcomes (r =-0.275, P = 0.116). 3D OPLL ratio and OPLL thickness had a significant negative relationship with JOA score (r =-0.502, P < 0.005 and r =-0.437, P < 0.05, respectively). In particular, 3D OPLL ratio was an independent risk factor for increased severity of myelopathy (B =-29.71, P < 0.05). The mild myelopathy group showed lower 3D OPLL ratio than the severe myelopathy group (0.092 vs. 0.148, P < 0.05). 3D method of measurement is superior to the conventional method in terms of evaluating the clinical state of symptomatic patients with OPLL. Higher 3D OPLL ratio has an adverse effect on the spinal cord. 3.

Factors Associated With Intramedullary MRI Abnormalities in Patients With Ossification of the Posterior Longitudinal Ligament

A retrospective clinical study of 113 patients with ossification of the posterior longitudinal ligament (OPLL), who underwent either anterior or posterior surgery between 2006 and 2009. To evaluate the risk factors affecting the intramedullary spinal cord changes in signal intensity on magnetic resonance imaging (MRI) for the patients with OPLL. The relationship between the intramedullary spinal cord changes in signal intensity on MRI and neurological deficits, as well as the surgical outcomes, has been described. To obtain better prognosis, early surgery should be conducted in patients with OPLL who have potential abilities to develop intramedullary spinal cord changes in signal intensity on MRI. Various factors may be affecting the development of intramedullary spinal cord changes in signal intensity on MRI. The clinical and radiographic data of 113 patients with OPLL who underwent either anterior or posterior surgery between 2006 and 2009 were reviewed. Age, sex, complication, mean occupying ratio of OPLL (the greatest thickness of OPLL divided by the anteroposterior diameter of the bony spinal canal), duration of symptoms, type of OPLL, preoperative Japanese Orthopedic Association (JOA) score, and range of motion of the cervical spine were collected. Logistic regression analysis was used. Changes in the intramedullary signal intensity on MRI were observed in 33 of the 113 patients. Statistical results show that duration of symptoms, occupying ratio of OPLL, preoperative JOA score, kyphosis, and instability of the cervical spine are the relevant risk factors for intramedullary spinal cord changes in signal intensity on MRI, with regression coefficients of 2.437, 0.953, -1.952, 2.093, and 1.516, respectively. For patients with OPLL, the longer the duration of the symptoms, or the higher occupying ratio of OPLL, or the lower preoperative JOA score, the greater the likelihood of intramedullary spinal cord changes in signal intensity on MRI. As intramedullary spinal cord changes in signal intensity on MRI indicated severe damage to spinal cord and poor prognosis as we described before, early surgery is suggested for patients with OPLL who manifest one of the following factors: prolonged symptoms, high occupying ratio, low preoperative JOA score, kyphosis, or instability of the cervical spine. These factors are closely related to the intramedullary spinal cord changes in signal intensity on MRI.

Ossification of the Posterior Longitudinal Ligament: Imaging Findings in the Era of Cross-Sectional Imaging.

Imaging appearance and classification systems of ossification of the posterior longitudinal ligament (OPLL) on computed tomography and magnetic resonance imaging will be reviewed. Computed tomography evaluation most accurately demonstrates OPLL length and thickness, whereas magnetic resonance imaging has the advantage of demonstrating abnormal signal in the cord. Neurologic symptoms are most common in the cervical spine and are related to the degree of spinal stenosis and presence of cord edema. Surgical treatment usually involves cases of cervical OPLL and includes anterior or posterior decompression.

Neurological Complications of Cervical Laminoplasty for Patients With Ossification of the Posterior Longitudinal Ligament—A multi-Institutional Retrospective Study

Retrospective multi-institutional study. To investigate the incidence of neurological deficits after cervical laminoplasty for ossification of the posterior longitudinal ligament (OPLL). According to analysis of long-term results, laminoplasty for cervical OPLL has been reported as a safe and effective alternative procedure with few complications. However, perioperative neurological complication rates of laminoplasty for cervical OPLL have not been well described. Subjects comprised 581 patients (458 men and 123 women; mean age: 62 ± 10 years; range: 30-86 years) who had undergone laminoplasty for cervical OPLL at 27 institutions between 2005 and 2008. Continuous-type OPLL was seen in 114, segmental-type in 146, mixed-type in 265, local-type in 24, and not judged in 32 patients. Postoperative neurological complications within 2 weeks after laminoplasty were analyzed in detail. Cobb angle between C2 and C7 (C2/C7 angle), maximal thickness, and occupying rate of OPLL were investigated. Pre- and postoperative magnetic resonance imaging was performed on patients with postoperative neurological complications. Open-door laminoplasty was conducted in 237, double-door laminoplasty in 311, and other types of laminoplasty in 33 patients. Deterioration of lower-extremity function occurred after laminoplasty in 18 patients (3.1%). Causes of deterioration were epidural hematoma in 3, spinal cord herniation through injured dura mater in 1, incomplete laminoplasty due to vertebral artery injury while making a trough in 1, and unidentified in 13 patients. Prevalence of unsatisfactory recovery not reaching preoperative level by 6-month follow-up was 7/581 (1.2%). Mean occupying rate of OPLL for patients with deteriorated lower-extremity function was 51.2 ± 13.6% (range, 21.0%-73.3%), significantly higher than the 42.3 ± 13.0% for patients without deterioration. OPLL thickness was also higher in patients with deterioration (mean, 6.6 ± 2.2 mm) than in those without deterioration (mean, 5.7 ± 2.0 mm). No significant difference in C2/C7 lordotic angle was seen between groups. Although most neurological deterioration can be expected to recover to some extent, the frequency of short-term neurological complications was higher than the authors expected.

Intraoperative ultrasonographic evaluation of posterior decompression via laminoplasty in patients with cervical ossification of the posterior longitudinal ligament: correlation with 2-year follow-up results

OBJECT The aim in this prospective study was to determine the morphological limitations of laminoplasty for cervical ossification of the posterior longitudinal ligament (OPLL) by using intraoperative ultrasonography and to investigate correlations between ultrasonographic findings and 2-year follow-up results. METHODS Included in this study were 40 patients who underwent double-door laminoplasty for cervical myelopathy due to OPLL. Intraoperative ultrasonography was used to evaluate posterior shift of the spinal cord after the posterior decompression procedure. To determine the decompression status of the cord, the authors classified ultrasonographic findings into 3 types on the basis of the presence or absence of spinal cord contact with OPLL after decompression: Type 1, noncontact; Type 2, contact and apart; and Type 3, contact. Patients were divided accordingly into Group 1, showing Type 1 or 2 findings, representing sufficient decompression; and Group 2, showing Type 3 findings with insufficient decompression. Preoperative sagittal alignment of the cervical spine (C2-7 angle) and preoperative maximal thickness of OPLL were compared between groups. The authors also investigated the morphological limitations of laminoplasty and 2-year follow-up results by using the Japanese Orthopedic Association (JOA) scoring system. RESULTS According to receiver operating characteristic curve analysis, an OPLL maximal thickness > 7.2 mm was a cutoff value for insufficient decompression. However, sufficient or insufficient decompression did not correlate with 2-year results, as determined by JOA scores. The C2-7 angle had no impact on ultrasonographic findings. CONCLUSIONS Laminoplasty has a morphological limitation for thick OPLLs, and a thickness > 7.2 mm represents a theoretical cutoff for residual cord compression after laminoplasty. According to 2-year results, however, laminoplasty can remain the first choice for any type of multiple-level OPLL.

A Patient With Two Re-surgeries for Delayed Myelopathy Due to Progression of Ossification of the Posterior Longitudinal Ligaments After Cervical Laminoplasty

Case report. To discuss the development of delayed myelopathy due to the progression of ossification of the posterior longitudinal ligament (OPLL) after cervical laminoplasty. The progression of OPLL after cervical laminoplasty for the treatment of OPLL is often shown in long-term follow-up; however, few patients with reoperation due to OPLL progression have been reported. The patient was a 70-year-old male carpenter. At 57-years of age, he underwent open door laminoplasty between C3 and C7 with dome-like laminectomy of C2 for the treatment of myelopathy due to mixed-type OPLL (continuous type at C3-C4 and segmental type at C5). Five years after the initial surgery, the disorder of skilled motor activity in the bilateral hands and ambulatory difficulties recurred as a result of cranial progression of OPLL (between C2 and C4). He underwent laminectomy and posterior fusion between C2 and C5 and returned to work. Four years after resurgery, the same symptoms recurred. CT revealed the progression of OPLL thickness at C5 level and longitudinal progression of OPLL to C6/7. Sagittal view of MRI demonstrated spinal cord compression between C5 and C6/7 because of OPLL at C5 and hypertrophic ligamentum flavum at C5-C6 and C6-C7. Posterior fusion extending up to C7 with laminectomy of C6 and C7 was performed. His symptoms were alleviated and he could walk again. We reported a patient with OPLL who had undergone resurgery twice because of myelopathy due to the progression of ossification. It was important to establish a sufficiently longitudinal and transverse decompression, taking the risk of the unexpected progression of ossification into consideration.

How Does the Ossification Area of the Posterior Longitudinal Ligament Thicken Following Cervical Laminoplasty?

Retrospective case series. To investigate the progression of the thickness of the ossification area over time following cervical laminoplasty. Cervical laminoplasty has become the standard technique for the treatment of patients with myelopathy due to ossification of the posterior longitudinal ligament (OPLL). However, OPLL is a progressive disease, and an increase in the area of ossification following laminoplasty affects the surgical results. To date, complete analysis of the thickness of OPLL progression has not been undertaken because changes in the ossification thickness are minor compared with those of the longitudinal axis. Fifty-five patients who were available for serial radiographs more than 5 years after cervical laminoplasty were included. The extent of ossification thickness was assessed using lateral radiographs of the cervical spine and computer software. The neurologic evaluation was graded using the Japanese Orthopedic Association score (JOA score). The associations between the progression of OPLL and the clinical and radiologic data were analyzed. We also evaluated the progression of the thickness of the ossification area over time following surgery. Twelve patients (21.8%) had progression in the OPLL thickness. Progression was marked in younger patients with the mixed or continuous types of OPLL. C3 involvement was also common in the patients with the OPLL progression. The progression of OPLL thickness was not directly related to the score-based recovery rate. The progression of OPLL was frequently observed at C2, C3, and C4 levels. Progression in OPLL thickness was detected in 42.1% of C2 ossifications, 13.3% of C3, 11.9% of C4, 4.1% of C5, 5.5% of C6, and 6.6% of C7. Young patients with continuous or mixed-type OPLL and C3 involvement of ossification had a risk for progression in OPLL thickness following surgery. As the increased thickness of ossified lesions directly causes the narrowing of the spinal canal, it is important to pay attention to these risk factors and the increase in ossification before and after cervical laminoplasty in the surgical treatment of patients with OPLL.

Ossification of the posterior longitudinal ligament of the cervical spine in Asian Indians — a multiracial comparison

Ossification of the Posterior longitudinal ligament (OPLL) has been thought to be a predominantly Japanese disease with few reports among the non-orientals and Caucasians. A prospective clinicoradiological study of 47 symptomatic Caucasoid Indians is reported. Twenty-seven patients presented with myelopathy, twelve with myeloradiculopathy and six with radiculopathy. ‘Total’ configuration of OPLL was the most frequent (70%). The most frequent location was at C3 and C4 levels. The thickness of OPLL ranged from 2.5 mm to 11.5 mm. Canal stenosis was most severe in patients with ‘total’ type of OPLL. Ossification of other spinal ligaments were seen in 50% of the patients. Twenty-one patients underwent decompressive laminectomy and twenty of them improved. The difference in the cervical canal diameters and the configuration of OPLL between the Japanese and our population (Caucasoid Indians) may be of therapeutic relevance.