Assessment of Cervical Myelopathy Risk in Ossification of the Posterior Longitudinal Ligament Patients With Spinal Cord Compression Based on Segmental Dynamic Versus Static Factors

A modified measurement method for functional spinal unit ROM of cervical spine

The interspinous process motion (ISM) method can provide a more accurate assessment of postoperative subaxial cervical fusion than Cobb angle method which is used more commonly in clinical practice. However, the ISM method presents the measurement results in millimeters which cannot be directly compared with the Cobb angle measurement data. We proposed a modified measurement method for cervical functional spinal unit range of motion  (FSU ROM) and evaluate its repeatability and reliability in measuring the ROM of the surgical segment after cervical artificial disc replacement surgery. A total of 81 patients who underwent cervical artificial disc replacement surgery in our department were retrospectively reviewed. Postoperative flexion-extension dynamic cervical radiographs were used for the measurement of FSU ROM of the surgical segment. The modified measurement method (M1) and the traditional Cobb angle measurement method (M2) were used. In the comparative analysis, there was no statistically significant difference between the two measurement methods (P > 0.05). Linear correlation study showed significant correlation between the two methods (P < 0.01), with a correlation coefficient of 0.947. Bland-Altman analysis showed the average difference between the two methods was 0.13°, the most of the measured data points fell within the 95% confidence interval. The M1 method demonstrated high intra-observer reliability (ICC = 0.957) and inter-observer reliability (ICC = 0.947). The M2 method showed good intra-observer reliability (ICC = 0.889) and good inter-observer reliability (ICC = 0.874). The M1 method yielded an SEM of 0.64° and an MDC of 1.49° for FSU ROM measurement, while the M2 method resulted in an SEM of 1.14° with an MDC of 2.66°.The modified measurement method for assessing cervical FSU ROM demonstrates satisfactory repeatability and reliability, provide higher measurement precision.

Reduced Vertebral Hounsfield Unit Values in the Bridging Group of Ossification-Related Segments in Patients with Ossification of the Posterior Longitudinal Ligament of the Cervical Spine

BACKGROUND

Increased systemic bone mineral density has been reported in patients with ossification of the posterior longitudinal ligament (OPLL). This study investigated the differences in vertebral Hounsfield unit (HU) values between the bridged and nonbridged groups of patients with OPLL of the cervical spine at the ossification-related segments.

METHODS

A total of 436 ossification-related segments from 157 patients were involved in the study. X-ray and computed tomography scans were used to assess the segmental cervical range of motion (ROM), C2-7 Cobb angle, K-line, ossification thickness, maximum canal occupancy, HU values, and presence and type of OPLL.

RESULTS

In terms of imaging parameters, HU values were significantly higher in the OPLL group (P < 0.001), whereas the ROM was greater in the control group (P < 0.05). In the OPLL group, the K-line positive group had a better C2-7 Cobb angle and greater T1 slope. The ossification-related segments were divided into bridging and nonbridging groups, with smaller vertebral HU values, thicker ossification lesions, greater canal occupation, and reduced interbody mobility in the bridging group. However, we found no significant correlation among segmental ROM, ossified material thickness, maximum canal occupancy of the ossified material, and segmental HU values.

CONCLUSIONS

We found that the mean HU value of the cervical spine in patients with OPLL was higher than that of the control group, and the ROM was smaller than that of the control group, with the smallest ROM in the continuous type. In the ossification-related segments, the bridging group exhibited lower vertebral HU values, reduced segmental mobility, and thicker ossification thickness.

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

BACKGROUND CONTEXT

Evaluating the gaps within the ossification of the posterior longitudinal ligament (OPLL) lesions, which may contribute to neurological symptoms, using conventional imaging techniques is challenging.

OBJECTIVE

This 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/SETTING

Retrospective cohort study.

PATIENT SAMPLE

Retrospective analysis of 116 patients diagnosed with cervical OPLL.

OUTCOME MEASURES

Presence of gaps in OPLL, presence of T2 high intensity in the cervical spinal cord, and OPLL thickness were evaluated.

METHODS

Lateral 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.

RESULTS

A 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 cooccurring 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.

CONCLUSIONS

3D-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.

Bone Density of Vertebral Bodies and Ossified Masses in Cervical Ossification of the Posterior Longitudinal Ligament: An Imaging Study Based on MRI, CT, and DEXA

Complications from anterior decompression fusion for cervical ossification of the posterior longitudinal ligament (OPLL) are often related to the bone mineral density (BMD) of vertebral bodies and ossified masses. The aim of this study was to clarify whether dual-energy X-ray absorptiometry (DEXA) T-scores reliably predict BMD in these structures, and whether vertebral bone quality (VBQ) and Hounsfield units (HU) can be effectively used to screen for osteopenia and osteoporosis. A total of 122 patients with cervical OPLL and 105 non-OPLL patients were included. Vertebral BMD was assessed by VBQ and HU, and ossified mass BMD was assessed by ossified mass bone quality (OMBQ) and ossification mass HU (OMHU). Overall, VBQ scores and HU values demonstrated weaker correlations with T-scores in the OPLL group compared with the non-OPLL group. Receiver operating characteristic curve analyses showed that VBQ and HU effectively discriminated osteopenia/osteoporosis in the OPLL cohort, with area under the curve values ranging from 0.763 to 0.827, similar to the non-OPLL. No significant differences in BMD were observed between the OPLL and non-OPLL groups based on the common assessment of VBQ, HU and DEXA-derived BMD (p > 0.05). Both OMBQ and OMHU showed good reliability and were significantly correlated with T-scores (p < 0.05). In patients with cervical OPLL, VBQ and HU remain effective screening tools for osteopenia/osteoporosis, potentially guiding or obviating the need for further DEXA scans. Additionally, our findings suggest that patients with lower T-scores may exhibit reduced BMD in both vertebral bodies and ossified masses.

Identification of Risk Factors for Primary Osteoporosis: The Role of Cervical Ligament Ossification

BACKGROUND Long-term clinical practice has suggested a possible association between ossification of cervical ligament (OCL) and primary osteoporosis (POP). However, there is a lack of relevant research data. This study aimed to clarify the potential relationship between OCL and POP, and propose new strategies for preventing the onset of POP. MATERIAL AND METHODS The study involved 107 patients. The patients' diagnosis included OCL (ossification of the posterior longitudinal ligament, ossification of the ligamentum flavum, and ossification of the nuchal ligament) and POP. Bone mineral density (BMD), types of OCL, types of ossification of posterior longitudinal ligament, age, sex, serum calcium, serum phosphorus, alkaline phosphatase, type I collagen amino-terminal extension peptide, type I collagen degradation products, osteocalcin N-terminal molecular fragments, 25-hydroxyvitamin D, and history of taking steroid drugs were collected. SPSS24.0 and GraphPad Prism 8 were used to obtain the risk factors for POP. RESULTS One-way analysis of variance found that OCL, ossification of posterior longitudinal ligament, alkaline phosphatase, and osteocalcin N-terminal molecular fragments had statistical significance on BMD of the femoral neck (P<0.05). The independent sample t test showed that patient sex had statistical significant effect on BMD (femoral neck) (P=0.036). Incorporating the above factors into multiple linear regression analysis, it was found that OCL, alkaline phosphatase, and osteocalcin N-terminal molecular fragments were risk factors affecting BMD of femoral neck (P<0.05). CONCLUSIONS OCL, osteocalcin N-terminal molecular fragments, and alkaline phosphatase are risk factors for POP.

Radiological and Clinical Significance of Cervical Dynamic Magnetic Resonance Imaging for Cervical Spondylotic Myelopathy

OBJECTIVE

The study compared the morphometric changes of the cervical spinal cord using dynamic magnetic resonance imaging (MRI) in patients with cervical spondylotic myelopathy (CSM) and assessed the correlation with kinematic changes, cord cross-sectional area (CSA), and high signal intensity (SI) on T2-weighted imaging (T2WI).

METHODS

Patients with CSM were evaluated through dynamic MRI for sagittal and axial CSA changes of the cervical cord, cerebrospinal fluid (CSF) reserve ratio, degree of cord impingement, cord compression rate, range of motion (ROM), and severity of SI on T2WI. The degree of cord impingement was evaluated using the Muhle grading system. Clinical outcomes were assessed using Japanese Orthopaedic Association scoring and Nurick grade.

RESULTS

The study included 191 patients (113 males) with a mean age of 55.34 ± 12.09 years. The lowest sagittal CSF reserve ratio and cord occupation rate were observed during extension. Cord impingement and SI change were more prevalent in extension-positioned MRI. There was no difference between ROM on dynamic radiographs and dynamic MRI. Preoperative cervical ROM was greater in patients with intensely high SI change.

CONCLUSION

Dynamic MRI is useful for evaluating neck movement. Patients with high SI had greater ROM before surgery but worse outcomes after. Neck extension exacerbated cervical stenosis and cord compression compared to flexion, and cervical spinal motion contributed to the severity of CSM. Cervical spinal motion should be carefully evaluated, particularly in hyperextension, to prevent worsening of CSM.

Factors Associated With Repeat Surgery in Cervical Ossification of the Posterior Longitudinal Ligaments: Minimum 8-year Follow-up Study

STUDY DESIGN

Single-center retrospective study.

OBJECTIVE

The objective of this study is to identify the factors leading to repeat surgery in patients with cervical ossification of the longitudinal ligament (OPLL) during a minimal 8-year follow-up after the initial surgery.

SUMMARY OF BACKGROUND DATA

The long-term effects of cervical OPLL are well known, but it's not always clear how many patients need to have surgery again because their neurological symptoms get worse.

METHODS

This study is included 117 patients who underwent surgery for cervical OPLL and had a follow-up of at least 8 years. OPLL type, surgical extent, surgical method, and sagittal radiological parameters were measured, and OPLL characteristics were analyzed.

RESULTS

The average age of patients at the time of surgery was 53.2 years, with a male-to-female ratio of 78:39. The median follow-up duration was 122 months (96-170 mo). Out of the total, 20 cases (17.1%) necessitated repeat surgery, among which 8 cases required surgery at the same site as the initial operation. The highest rate of repeat surgery was observed in patients who underwent total laminectomy without fusion (TL), where 6 out of 21 patients (29%) needed a second surgery, and 5 of these (23%) involved the same surgical site. Patients who underwent repeat surgery at the same site exhibited a greater range of motion (ROM) one year postsurgery (16.4 ± 8.5° vs. 23.1 ± 12.7°, P =0.041). In addition, the ROM at 1 year was higher in patients who underwent TL compared with those who had laminoplasty. Furthermore, the recurrence rate for hill-shape OPLL was higher at 30.8% compared to 10% for plateau-shape OPLL ( P = 0.05).

CONCLUSION

Larger cervical ROM 1 year after surgery is related to repeat surgery at the same level as previous surgery, especially in laminectomy without fusion surgery.

Management of Cerebrospinal Fluid Leakage by Pump-Regulated Volumetric Continuous Lumbar Drainage Following Anterior Cervical Decompression and Fusion for Ossification of the Posterior Longitudinal Ligament

OBJECTIVE

Cerebrospinal fluid (CSF) leakage is a major concern related to anterior cervical decompression and fusion for ossification of the posterior longitudinal ligament (OPLL). We propose a management algorithm for CSF leakage following anterior cervical decompression and fusion for OPLL involving the use of pump-regulated volumetric continuous lumbar drainage.

METHODS

We retrospectively reviewed patients who underwent anterior cervical decompression and fusion for OPLL and were managed with the proposed algorithm between March 2018 and July 2022. The proposed management algorithm for CSF leakage by pump-regulated volumetric continuous lumbar drainage was as follows. On exposure of the arachnoid membrane with or without CSF leakage, a dural sealant patch was applied to manage the dural defect. In case of persistent CSF leakage despite application of the dural sealant patch, patients underwent pump-regulated volumetric continuous lumbar drainage.

RESULTS

Fifty-one patients were included in the study. CSF leakage occurred in 14 patients. Of these 14 patients, 9 patients underwent lumbar drain insertion according to the proposed management algorithm. Successful resolution of CSF leakage was observed in 8 of the 9 patients who underwent lumbar drainage. All patients were encouraged to ambulate without concern of CSF overdrainage due to gravity, because it could be avoided with pump-regulated volumetric continuous CSF drainage. Therefore, complications associated with absolute bed rest or CSF overdrainage were not observed.

CONCLUSION

The proposed management algorithm with pump-regulated volumetric continuous lumbar drainage showed safety and efficacy for management of CSF leakage following anterior decompression and fusion for OPLL.