Comparative Study of Surgical Treatment and Nonsurgical Follow Up for Thoracic Ossification of the Posterior Longitudinal Ligament: Radiological and Clinical Evaluation

Perioperative complications and cost of posterior decompression with fusion in thoracic spine for ossification of the posterior longitudinal ligament and ossification of the ligamentum flavum -a comparative study using a national inpatient database

BACKGROUND

Although posterior decompression with fusion (PDF) are effective for treating thoracic myelopathy, surgical treatment has a high risk of various complications. There is currently no information available on the perioperative complications in thoracic ossification of the longitudinal ligament (T-OPLL) and thoracic ossification of the ligamentum flavum (T-OLF). We evaluate the perioperative complication rate and cost between T-OPLL and T-OLF for patients underwent PDF.

METHODS

Patients undergoing PDF for T-OPLL and T-OLF from 2012 to 2018 were detected in Japanese nationwide inpatient database. One-to-one propensity score matching between T-OPLL and T-OLF was performed based on patient characteristics and preoperative comorbidities. We examined systemic and local complication rate, reoperation rate, length of hospital stays, costs, discharge destination, and mortality after matching.

RESULTS

In a total of 2,660 patients, 828 pairs of T-OPLL and T-OLF patients were included after matching. The incidence of systemic complications did not differ significantly between the T-OPLL and OLF groups. However, local complications were more frequently occurred in T-OPLL than in T-OLF groups (11.4% vs. 7.7% P = 0.012). Transfusion rates was also significantly higher in the T-OPLL group (14.1% vs. 9.4%, P = 0.003). T-OPLL group had longer hospital stay (42.2 days vs. 36.2 days, P = 0.004) and higher medical costs (USD 32,805 vs. USD 25,134, P < 0.001). In both T-OPLL and T-OLF, the occurrence of perioperative complications led to longer hospital stay and higher medical costs. While fewer patients in T-OPLL were discharged home (51.6% vs. 65.1%, P < 0.001), patients were transferred to other hospitals more frequently (47.5% vs. 33.5%, P = 0.001).

CONCLUSION

This research identified the perioperative complications of T-OPLL and T-OLF in PDF using a large national database, which revealed that the incidence of local complications was higher in the T-OPLL patients. Perioperative complications resulted in longer hospital stays and higher medical costs.

Clinical progression of ossification of the ligamentum flavum in thoracic spine: a 10- to 11-year follow-up study

BACKGROUND

Thoracic ossification of ligamentum flavum (TOLF) can be asymptomatic and progress insidiously. But, long-term follow-up results of clinical progression of TOLF are still unknown.

METHODS

The clinical progression of 81 patients with TOLF at our center, followed for 10 to 11 (mean, 10.3) years from May 2010 to November 2021, were analyzed. Among them, 51 patients with thoracic myelopathy were caused by single- or multi-segment TOLF, and received partial TOLF resection (30 patients) or total TOLF resection (21 patients). The remaining 30 patients showed TOLF on imaging examinations, but TOLF was not the responsible compressing factor causing myelopathy and with no TOLF resection. The mJOA score (total 11 scores) and spinal operation were used to evaluate the clinical progression at follow-up.

RESULTS

During the 10- to 11-year follow-up of 81 TOLF patients, 71 (87.7%) had no deterioration of neurological function, and 10 (12.3%) patients had deterioration of neurological function and had another spinal operation, including only 4 (4.9%) suffered thoracic myelopathy caused by the progression of TOLF; 6 (7.4%) for other spinal diseases: 2 (2.5%) had fall damage and acute spinal cord injury at the TOLF level; 2 (2.5%) had thoracic myelopathy caused by ossification of posterior longitudinal ligament (OPLL); 2 (2.5%) had cervical spondylosis and received cervical operation.

CONCLUSIONS

Most TOLF (87.7%) patients had no clinical progression and received no reoperations for TOLF in the ten-year dimension (mean, 10.3 years). Narrow spinal canal for TOLF increases the risk of traumatic paraplegia.

Distinct progression pattern of ossification of the posterior longitudinal ligament of the thoracic spine versus the cervical spine: a longitudinal whole-spine CT study

OBJECTIVE

Data regarding risk factors for the progression of ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine are scarce. Therefore, in this study, the authors aimed to elucidate the difference in the radiographic progression pattern of OPLL and its risk factors between cervical and thoracic OPLL using longitudinally acquired whole-spine CT scans.

METHODS

Overall, 123 patients with symptomatic OPLL who underwent repeated whole-spine CT examinations, with an average interval of 49 months (at least 3 years) between scans, were retrospectively reviewed. Progression of OPLL was assessed to compare the distribution of OPLL over the entire spine on the initial and final CT scans. Patients were divided into a cervical OPLL (C-OPLL) group and a thoracic OPLL (T-OPLL) group according to the location of the main lesion. The progression pattern of OPLL and its risk factors were compared between the two groups using the Student t-test or Mann-Whitney U-test.

RESULTS

In the C-OPLL group, 15 (22.1%) of 68 patients had OPLL progression, of whom 12 patients (80.0%) had progression only in the cervical spine and 3 patients (20.0%) had progression in multiple regions (cervical and thoracic/lumbar). In the T-OPLL group, 16 (29.1%) of 55 patients had OPLL progression, of which 3 patients (18.8%) had progression only in the thoracic spine and 8 patients (50.0%) had progression in multiple regions. Young age was a common risk factor for OPLL progression regardless of the location of OPLL, and this trend was more pronounced in the T-OPLL group than in the C-OPLL group. High BMI, male sex, and multilevel, severe T-OPLL were identified as independent risk factors for progression of T-OPLL (OR 1.19, 95% CI 1.03-1.37; OR 10.5, 95% CI 1.39-81.94; and OR 1.24, 95% CI 1.16-1.45, respectively).

CONCLUSIONS

Patients with T-OPLL are predisposed to diffuse progression of OPLL over the entire spine, whereas patients with C-OPLL are likely to have progression in only the cervical spine. Young age and high BMI are significant risk factors for OPLL progression, especially in patients with T-OPLL. Our study highlights the need for continued follow-up in patients with T-OPLL, especially in young patients and those with obesity, for early detection of spinal cord and cauda equina symptoms due to the progression of OPLL throughout the spine.

High Body Mass Index Is Associated with an Increased Risk of the Onset and Severity of Ossification of Spinal Ligaments

Background

Ossification of the posterior longitudinal ligament (OPLL) and that of ligamentum flavum (OLF) are the main types of the ossification of spinal ligaments (OSL) that cause the thoracic myelopathy. Although several studies have investigated the relationship of body mass index (BMI) with the onset or severity of OSL, it remains unverified due to the contradictory results of existing evidence. A systematic review and meta-analysis were performed in this work to determine the relationship of BMI with the onset and severity of OSL.

Methods

PubMed, EMBASE, Web of Science, and Cochrane Library were comprehensively searched online for relevant studies focusing on the relationship of BMI with the onset or severity of the OSL. The difference in BMI of OSL (or severe OSL group) and non-OSL (or nonsevere OSL group) groups was evaluated using the mean difference (MD) with a corresponding 95% confidence interval (CI).

Results

Fifteen studies were included in this systematic review and meta-analysis. The BMI of the OSL group was significantly higher than that of the non-OSL group (MD = 1.70 kg/m², 95% CI = 1.02–2.39 kg/m², and P < 0.01). Similar results were observed in the subgroup analysis of female (P < 0.01), OPLL (P < 0.01), and OLF (P < 0.01) populations. Three studies reported a significant association of BMI with the ossification index of OSL and the standardized regression coefficient ranging from 0.11 to 0.43 (P < 0.05). Moreover, a significantly higher BMI was observed in the severe OSL group compared with that in the nonsevere OSL group (MD = 3.09, 95% CI, 0.22–5.97 kg/m², and P = 0.04).

Conclusion

The significant association of high BMI with the onset and severity of OSL may provide new evidence and insights into the mechanism research and management of OSL.

Comparison of laminoplasty and posterior fusion surgery for cervical ossification of posterior longitudinal ligament

This prospective multicenter study, established by the Japanese Ministry of Health, Labour and Welfare and involving 27 institutions, aimed to compare postoperative outcomes between laminoplasty (LM) and posterior fusion (PF) for cervical ossification of the posterior longitudinal ligament (OPLL), in order to address the controversy surrounding the role of instrumented fusion in cases of posterior surgical decompression for OPLL. 478 patients were considered for participation in the study; from among them, 189 (137 and 52 patients with LM and PF, respectively) were included and evaluated using the Japanese Orthopaedic Association (JOA) scores, the JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), and radiographical measurements. Basic demographic and radiographical data were reviewed, and the propensity to choose a surgical procedure was calculated. Preoperatively, there were no significant differences among the participants in terms of patient backgrounds, radiographical measurements (K-line or cervical alignment on X-ray, OPLL occupation ratio on computed tomography, increased signal intensity change on magnetic resonance imaging), or clinical status (JOA score and JOACMEQ) after adjustments. The overall risk of perioperative complications was found to be lower with LM (odds ratio [OR] 0.40, p = 0.006), and the rate of C5 palsy occurrence was significantly lower with LM (OR 0.11, p = 0.0002) than with PF. The range of motion (20.91° ± 1.05° and 9.38° ± 1.24°, p < 0.0001) in patients who had PF was significantly smaller than in those who had LM. However, multivariable logistic regression analysis showed no significant difference among the participants in JOA score, JOA recovery rate, or JOACMEQ improvement at two years. In contrast, OPLL progression was greater in the LM group than in the PF group (OR 2.73, p = 0.0002). Both LM and PF for cervical myelopathy due to OPLL had resulted in comparable postoperative outcomes at 2 years after surgery.

Postoperative progression of ligamentum flavum ossification after posterior instrumented surgery for thoracic posterior longitudinal ligament ossification: long-term outcomes during a minimum 10-year follow-up

OBJECTIVE

The authors sought to investigate clinical and radiological outcomes after thoracic posterior fusion surgery during a minimum of 10 years of follow-up, including postoperative progression of ossification, in patients with thoracic ossification of the posterior longitudinal ligament (T-OPLL).

METHODS

The study participants were 34 consecutive patients (15 men, 19 women) with an average age at surgery of 53.6 years (range 36-80 years) who underwent posterior decompression and fusion surgery with instrumentation at the authors' hospital. The minimum follow-up period was 10 years. Estimated blood loss, operative time, pre- and postoperative Japanese Orthopaedic Association (JOA) scores, and JOA score recovery rates were investigated. Dekyphotic changes were evaluated on plain radiographs of thoracic kyphotic angles and fusion levels pre- and postoperatively and 10 years after surgery. The distal junctional angle (DJA) was measured preoperatively and at 10 years after surgery to evaluate distal junctional kyphosis (DJK). Ossification progression at distal intervertebrae was investigated on CT.

RESULTS

The Cobb angles at T1-12 were 46.8°, 38.7°, and 42.6°, and those at the fusion level were 39.6°, 31.1°, and 34.1° pre- and postoperatively and at 10 years after surgery, respectively. The changes in the kyphotic angles from pre- to postoperatively and to 10 years after surgery were 8.0° and 7.2° at T1-12 and 8.4° and 7.9° at the fusion level, respectively. The DJA changed from 4.5° postoperatively to 10.9° at 10 years after surgery. There were 11 patients (32.3%) with DJK during follow-up, including 4 (11.8%) with vertebral compression fractures at lower instrumented vertebrae or adjacent vertebrae. Progression of ossification of the ligamentum flavum (OLF) on the caudal side occurred in 8 cases (23.6%), but none had ossification of the posterior longitudinal ligament (OPLL) progression. Cases with OLF progression had a significantly lower rate of DJK (0% vs 38.5%, p < 0.01), a lower DJA (3.4° vs 13.2°, p < 0.01), and a smaller change in DJA at 10 years after surgery (0.8° vs 8.1°, p < 0.01).

CONCLUSIONS

Posterior decompression and fusion surgery with instrumentation for T-OPLL was found to be a relatively safe and stable surgical procedure based on the long-term outcomes. Progression of OLF on the caudal side occurred in 23.6% of cases, but cases with OLF progression did not have DJK. Progression of DJK shifts the load in the spinal canal forward and the load on the ligamentum flavum is decreased. This may explain the lack of ossification in cases with DJK.

Clinical Comparison of Selective versus Nonselective Decompression for Symptomatic Tandem Stenosis of the Cervical and Thoracic Spine: A Retrospective Cohort Study

OBJECTIVE

The aim of the present paper was to reveal the clinical differences between selective and nonselective decompression for symptomatic tandem stenosis of the cervical and thoracic spine (TSCTS).

METHODS

A total of 34 patients were eligible and included in the study. Among them, 8 patients underwent selective cervical decompression (CD), 15 patients underwent selective thoracic decompression (TD), and 11 patients underwent combined CD and TD (CTD) surgery. Age, sex, operative time, intraoperative blood loss, postoperative hospital stay, inpatient expenditure, preoperative upper Japanese Orthopaedic Association (JOA) rate, canal occupation rate, high-intensity T2-weighted image (T2WI) of the spinal cord, and preoperative and postoperative JOA scores were compared among the three groups.

RESULTS

The CD group had shorter operative time (138.8 ± 36.1 vs 229.7 ± 95.8 vs 328.6 ± 94.8, min, P < 0.001), less intraoperative blood loss (141.3 ± 116.7 vs 496.7 ± 361.8 vs 654.6 ± 320.5, mL, P = 0.004), and shorter postoperative hospital stay (4.6 ± 1.6 vs 9.0 ± 3.5 vs 10.3 ± 6.6, days, P = 0.008), as well as lower preoperative upper JOA rate (34.1 ± 5.6 vs 53.9 ± 8.4 vs 48.2 ± 15.2, %, P = 0.001) than the TD and CTD groups. The CTD group had higher inpatient expenditure than the CD and TD groups (87,850 ± 18,379 vs 55,100 ± 12,890 vs 55,772 ± 15,715, CNY, P < 0.001). The cervical canal occupation rates were similar among different groups (P > 0.05); however, the TD group showed a higher thoracic canal occupation rate than the CD group (58.3 ± 14.7 vs 43.3 ± 12.3, %, P = 0.035). All positive levels in high-intensity T2WI of the spinal cord were decompressed. The preoperative JOA scores as well as the postoperative JOA scores at 6 months and at last follow-up were comparable among the three groups (P > 0.05). Similarly, the JOA recovery rate showed no significant difference among the groups (P > 0.05).

CONCLUSION

Selective CD or TD alone demonstrated similar clinical effectiveness to nonselective and combined CTD for TSCTS. Individualized surgical decision should be made after meticulous assessments of clinical and radiological manifestations, general patient condition, and socioeconomic factors.

Dynamic changes in longitudinal stretching of the spinal cord in thoracic spine: Focus on the spinal cord occupation rate of dural sac

OBJECTIVES

This study aimed to evaluate the anteroposterior diameters and cross-sectional areas of the dural sac and spinal cord in the thoracic spine, to elucidate the spinal cord occupation rate of the dural sac in these dynamic changes for each level using multidetector-row computed tomography (MDCT).

PATIENTS AND METHODS

Fifty patients with cervical or lumbar spinal disease were prospectively enrolled. After preoperative myelography, MDCT was performed at maximum passive flexion and extension. The anteroposterior diameter and cross-sectional area of the dural sac and spinal cord in the axial plane and the thoracic spinal cord length in the sagittal plane were measured. The spinal cord occupation rate in the dural sac was calculated.

RESULTS

The spinal cord occupation rate of the dural sac in anteroposterior diameter was lower on flexion than on extension, with significant differences from the T1/T2 to T11/T12 levels (p < 0.0001). The spinal cord occupation rate of the dural sac in cross-sectional area was lower on flexion than on extension, with significant differences except from T3/T4 to T6/T7 levels (p < 0.01). There was a bimodal increase in the occupation rate with elevations at the cervicothoracic junction and thoracolumbar junction. The thoracic spinal cord length on flexion was significantly longer than that on extension (p < 0.0001).

CONCLUSIONS

The spinal cord occupation rate of the dural sac was lower on flexion than on extension, despite thoracic spine being considered a rigid region. The dynamic changes in longitudinal stretching and shrinkage of the spinal cord affected the occupation rate.

Transthoracic microsurgical anterior decompression without fusion for ossification of the posterior longitudinal ligament in the thoracic spine

OBJECTIVE

The authors aimed to analyze outcomes following transthoracic microsurgical anterior decompression of thoracic ossification of the posterior longitudinal ligament (T-OPLL), which was causing myelopathy, and determine the predictive factors for surgical outcomes.

METHODS

Patients who underwent transthoracic microsurgical anterior decompression without fusion for the treatment of T-OPLL from December 2014 to May 2019 were included. Demographic, radiological, and perioperative data and clinical outcomes of 35 patients were analyzed. The modified Japanese Orthopaedic Association (mJOA) score and recovery rate were used to evaluate functional outcomes.

RESULTS

A total of 35 consecutive patients (8 men and 27 women; mean age 52.2 ± 10.8 years) were enrolled in this study, and the mean follow-up period was 65.5 ± 51.9 months. The mean mJOA score significantly improved after surgery (5.9 ± 1.8 vs 8.3 ± 1.5, p < 0.001), with a mean recovery rate of 47.7% ± 24.5%. The visual analog scale (VAS) score significantly improved after surgery (7.3 ± 1.3 vs 4.3 ± 0.7, p < 0.001). The outcome was excellent in 4 patients (11.4%), good in 21 patients (60.0%), fair in 4 patients (11.4%), unchanged in 5 patients (14.3%), and worsened in 1 patient (2.9%). There were 12 cases of CSF leakage, 1 case of epidural hematoma, 1 case of pleural effusion, and 1 case of pneumothorax. Age, preoperative kyphotic angle, anteroposterior length of T-OPLL at the maximally affected level, and mass occupying rate were identified as predictors associated with postoperative outcome. A multivariate regression analysis revealed that age and preoperative kyphotic angle were independent risk factors for postoperative outcomes.

CONCLUSIONS

Transthoracic microsurgical anterior decompression without fusion achieved favorable clinical and radiological outcomes for treating T-OPLL with myelopathy. Patient age and preoperative kyphotic angle were independent risk factors for lower recovery rate.

Ossification of the ligamentum flavum in the upper cervical spine: A report of two cases and literature review

Ossification of the ligamentum flavum (OLF) is rarely observed in the cervical spine, particularly not in the upper cervical spine. The present report describes two cases of OLF combined with cervical myelopathy and provides a literature review with a comparative analysis of previous studies and the present cases. Pre-operative CT, MRI and histological examination were performed to confirm the diagnosis of these patients (A 37-year-old female and 63-year-old male). In both cases, histological examination of surgical specimens revealed OLF. The symptoms of the two patients significantly improved after surgery and no recurrence was observed at 13 months after surgery. Furthermore, the clinical outcomes were satisfactory and the internal fixation was solid in the two cases. Review of the literature suggested that further research is required to reveal the optimal treatment methods for upper cervical OLF.

Efficacy and Safety Analysis of Ultrasonic Bone Curette in the Treatment of Thoracic Spinal Stenosis

Objective

To investigate the efficacy and safety of ultrasonic bone curette in treating thoracic spinal stenosis.

Methods

A total of 30 patients of thoracic spinal stenosis who underwent posterior thoracic decompression in the hospital from December 2015 to 2017 were enrolled. Of these, 18 patients (group A) underwent posterior thoracic decompression using ultrasonic bone curette; and 12 patients underwent the treatment using a high‐speed drill (group B). The time of laminectomy, amount of intraoperative blood loss, presence or absence of cerebrospinal fluid leakage, and nerve root injury were recorded. All patients underwent X‐ray, computed tomography with three‐dimensional reconstruction, and magnetic resonance imaging before and after surgery. The Frankel classification and the Japanese Orthopaedic Association (JOA) scores were used to assess the neurological function and neurological recovery in patients. The measured data were statistically processed and analyzed using SPSS21.0 software, and the measurement data were expressed as mean ± SD.

Results

In groups A and B, the average time for single‐segment laminectomy was 3.3 ± 1.2 min and 6.0 ± 1.8 min and the mean bleeding volume was 105.5 ± 43.3 mL and 177.4 ± 54.7 mL, respectively, with a statistically significant difference between the groups. The difference in JOA scores before and after surgery in groups A and B was statistically significant. No significant difference was found between the groups, in group A, the improvement rate of nerve function at the last follow‐up was 71% and in group B, the improvement rate at the last follow‐up was 70%. In group A, at last follow‐up, two patients had Frankel grade B injury, one had grade C injury, seven had grade D injury, and eight had grade E injury. In group B, at last follow‐up, one patient had Frankel grade B injury, one had grade C injury, five had grade D injury, and five had grade E injury. The Frankel classification of both groups A and B significantly improved. Four patients experienced cerebrospinal fluid leakage in group A and five in group B, with no significant difference between the groups. There was no nerve root injury in both groups, and no complications, such as pulmonary infection and urinary tract infection, occurred after operation.

Conclusions

With the use of ultrasonic bone curette in posterior thoracic decompression, the decompression surgery could be completed relatively safely and quickly. It effectively reduced the amount of intraoperative blood loss.

Connection of discontinuous segments in early functional recovery from thoracic ossification of the posterior longitudinal ligament treated with posterior instrumented surgery

OBJECTIVE

The objective of this study was to investigate the relationship between morphological changes in thoracic ossification of the posterior longitudinal ligament (T-OPLL) and postoperative neurological recovery after thoracic posterior fusion surgery. Changes of OPLL morphology and postoperative recovery in cases with T-OPLL have not been examined.

METHODS

In this prospective study, the authors evaluated data from 44 patients (23 male and 21 female) who underwent posterior decompression and fusion surgery with instrumentation for the treatment of T-OPLL at our hospital. The patients' mean age at surgery was 50.7 years (range 38-68 years). The minimum duration of follow-up was 2 years. The location of thoracic ossification of the ligamentum flavum (T-OLF), T-OLF at the OPLL level, OPLL morphology, fusion range, estimated blood loss, operative time, pre- and postoperative Japanese Orthopaedic Association (JOA) scores, and JOA recovery rate were investigated. Reconstructed sagittal multislice CT images were obtained before and at 3 and 6 months and 1 and 2 years after surgery. The basic fusion area was 3 vertebrae above and below the OPLL lesion. All parameters were compared between patients with and without continuity across the disc space at the OPLL at 3 and 6 months after surgery.

RESULTS

The preoperative morphology of OPLL was discontinuous across the disc space between the rostral and caudal ossification regions on sagittal CT images in all but one of the patients. Postoperatively, these segments became continuous in 42 patients (97.7%; occurring by 6.6 months on average) without progression of OPLL thickness. Patients with continuity at 3 months had significantly lower rates of diabetes mellitus (p < 0.05) and motor palsy in the lower extremities (p < 0.01). The group with continuity also had significantly higher mean postoperative JOA scores at 3 (p < 0.01) and 6 (p < 0.05) months and mean JOA recovery rates at 3 and 6 months (both p < 0.01) after surgery.

CONCLUSIONS

Preoperatively, discontinuity of rostral and caudal ossified lesions was found on CT in all patients but one of this group of 44 patients who needed surgery for T-OPLL. Rigid fixation with instrumentation may have allowed these segments to connect at the OPLL. Such OPLL continuity at an early stage after surgery may accelerate spinal cord recovery.

Surgical Outcomes According to Dekyphosis in Patients with Ossification of the Posterior Longitudinal Ligament in the Thoracic Spine

Objective

Ossification of posterior longitudinal ligament (OPLL) in the thoracic spine may cause chronic compressive myelopathy that is usually progressive, and unfavorable by conservative treatment. Although surgical intervention is often needed, the standard surgical method has not been established. Recently, it has been reported that posterior decompression with dekyphosis is effective surgical technique for favorable clinical outcome. The purpose of this study was to evaluate the surgical outcomes in patients with thoracic OPLL according to dekyphosis procedure and to identify predictive factors for the surgical results.

Methods

A total of 25 patients with thoracic OPLL who underwent surgery for myelopathy from May 2004 to March 2017, were retrospectively reviewed. Patients with cervical myelopathy were excluded. We assessed the clinical outcomes according to various surgical approaches. The modified Japanese orthopedic association (JOA) scores for the thoracic spine (total, 11 points) and JOA recovery rates were used for investigating surgical outcomes.

Results

Of the 25 patients, 10 patients were male and the others were female. The mean JOA score was 6.7±2.3 points preoperatively and 8.8±1.8 points postoperatively, yielding a mean recovery rate of 53.8±31.0%. The mean patients’ age at surgery was 52.4 years and mean follow-up period was 40.2 months. According to surgical approaches, seven patients underwent anterior approaches, 13 patients underwent posterior approaches, five patients underwent combined approaches. There was no significant difference of the surgical outcomes related with different surgical approaches. Age (≥55 years) and high signal intensity on preoperative magnetic resonance (MR) image in the thoracic spine were significant predictors of the lower recovery rate after surgery (p<0.05). Posterior decompression with dekyphosis procedure was related to the excellent surgical outcomes (p=0.047). Dekyphosis did not affect the complication rates.

Conclusion

In this study, our result elucidated that old age (≥55 years) and presence of intramedullary high signal intensity on preoperative MR images were risk factors related to poor surgical outcomes. In the meanwhile, posterior decompression with dekyphosis affected favorable clinical outcome. Posterior approach with dekyphosis procedure can be a recommendable surgical option for favorable results.

Perioperative Complications After Surgery for Thoracic Ossification of Posterior Longitudinal Ligament: A Nationwide Multicenter Prospective Study

STUDY DESIGN

Prospective, multicenter, nationwide study.

OBJECTIVE

To investigate perioperative complications and risk factors in surgery for thoracic ossification of the posterior longitudinal ligament (T-OPLL) using data from the registry of the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament.

SUMMARY OF BACKGROUND DATA

There is no prospective multicenter study of surgical complications and risk factors for T-OPLL, and previous multicenter retrospective studies have lacked details.

METHODS

Surgical methods, preoperative radiographic findings, pre- and postoperative thoracic myelopathy (Japanese Orthopaedic Association [JOA] score), prone and supine position test (PST), intraoperative ultrasonography, and intraoperative neurophysiological monitoring (IONM) were investigated prospectively in 115 cases (males: 55, females: 60, average age 53.1 y). Factors related to perioperative complications and risk factors for postoperative motor palsy were identified.

RESULTS

Posterior decompression and fusion with instrumentation with or without dekyphosis was performed in 85 cases (74%). The JOA recovery rate at 1 year after surgery in all cases was 55%. Motor palsy occurred postoperatively in 37 cases (32.2%), with a mean recovery period of 2.7 months. A long recovery period for postoperative motor palsy was significantly associated with a high number of T-OPLL levels (P < 0.0001), lower preoperative JOA score (P < 0.05), and greater estimated blood loss (P < 0.05). Perioperative complications or postoperative motor palsy were significantly related to a higher number of T-OPLL levels, comorbid ossification of ligamentum flavum rate, lower preoperative JOA score, higher preoperative positive PST rate, more surgical invasiveness, a lower rate of intraoperative spinal cord floating in ultrasonography, and higher rate of deterioration of IONM.

CONCLUSION

This study firstly demonstrated the perioperative complications with high postoperative motor palsy rate in a nationwide multicenter prospective study. Surgical outcomes for T-OPLL should be improved by identifying and preventing perioperative complications with significant risk factors.

LEVEL OF EVIDENCE

3.

Clinical relation among dural adhesion, dural ossification, and dural laceration in the removal of ossification of the ligamentum flavum

BACKGROUND CONTEXT

Dural laceration frequently occurs during surgery in patients with ossification of the ligamentum flavum (OLF), mainly because of dural adhesion (DA) and dural ossification (DO) between the ligamentum flavum and the dura mater. However, the radiological predictive factors of DA in OLF have rarely been reported.

PURPOSE

The objective of this study was to determine the preoperative radiological signs for predicting intraoperative DA in OLF by using preoperative magnetic resonance imaging (MRI) and computed tomography (CT).

STUDY DESIGN

This is a retrospective study.

PATIENT SAMPLE

This study included 182 patients who underwent decompressive laminectomy and OLF removal from 2005 to 2014.

OUTCOME MEASURE

Demographic data, preoperative neurologic status, surgical procedure and results, and intraoperative and postoperative complications were analyzed. Clinical outcome was assessed with the Japanese Orthopaedic Association score.

MATERIALS AND METHODS

Depending on the morphologic appearance of OLF in preoperative radiographs, we aimed to investigate the prevalence of intraoperative DA and DO. We used the following factors of representative classifications: (1) surface appearance, (2) "double-layer" or "tram-track" sign, (3) cross-sectional area of the stenosed level, (4) Sato classification as axial classification, (5) Kuh classification as sagittal classification, and (6) high-signal-intensity change on T₂-weighted MRI.

RESULTS

Intraoperative evidence of DA was observed in 52 patients (29%), and DO was observed in 23 patients (13%). Twenty-seven patients (15%) had dural laceration during surgery. Statistically, DA was closely associated with the non-uniform type of surface appearance (odds ratio 5.396, p=.001) and with the presence of either a double-layer sign or a tram-track sign (odds ratio 11.525, p<.001). In the preoperative CT and MRI, 21 out of 23 patients with DO showed a "double-layer sign" or a "tram-track sign."

CONCLUSIONS

This study identified two predictive factors of DA in OLF, which were the non-uniform surface appearance and the presence of a double-layer sign or a tram-track sign. The presence of DO in OLF was closely associated with a double-layer sign or a tram-track sign in the preoperative radiological images.