Hiroshi Uei

Effectiveness of posterior decompression for patients with ossification of the posterior longitudinal ligament in the thoracic spine: usefulness of the ossification-kyphosis angle on MRI.

Study Design. A reliability study was conducted. Objective. To report the utility of the ossification- kyphosis angle of a decompression site in the sagittal view of MRI in the preoperative evaluation of the effectiveness of posterior decompression for patients with ossification of the posterior longitudinal ligament in the thoracic spine. Summary of Background Data. In patients with ossification of the posterior longitudinal ligament, in the thoracic spine, posterior decompression may not always be effective for those with physiologic kyphosis; however, posterior decompression is sometimes useful for patients with multilevel lesions or with ossification of the ligamentum flavum. Therefore, it is necessary to evaluate the indications or limitations of posterior decompression before surgery. Methods. The indications or limitations of posterior decompression for this disease were reviewed from the findings of intraoperative ultrasonography and various parameters on preoperative imaging in 22 patients with thoracic myelopathy. Results. Thirteen patients had echo-free space and 9 patients had no echo-free space in intraoperative ultrasonography after posterior decompression. In the kyphosis angle of the decompression site and the configuration of the maximal prominent OPLL, there was no significant difference between the group with echo-free space and the group without echo-free space (P = 0.49, P = 0.55). On the other hand, the ossification-kyphosis angle of the decompression site was more than 23° in all patients with no echo-free space (23°–34°, 28.2° ± 3.6°), and it was less than 23° in all patients with echo-free space (10°–23°, 17.4° ± 4.1°). There was also significant difference between the groups statistically (P < 0.01, P = 1.50789E-06). In addition, in the occupation rate of the greatest prominence of the OPLL, there was statistically significant difference between the groups (P = 0.032). Conclusion. The ossification-kyphosis angle in the sagittal view of MRI has potential as an indicator of the effectiveness of posterior decompression in this disease. It is thought that there is a critical point of posterior decompression at nearly 23° of the ossification-kyphosis angle of the decompression site. When the ossification-kyphosis angle is more than 20°, the presence of echo free space should be carefully confirmed in intraoperative ultrasonography.

Gene expression changes in an early stage of intervertebral disc degeneration induced by passive cigarette smoking.

Study Design. This study attempts to determine the molecular changes in intervertebral disc degeneration of rats induced by passive cigarette smoking. Objectives. To quantitate and compare the gene expression levels in intervertebral discs from passively cigarette smoking rats and nonsmoking rats. Summary of Background Data. The molecular mechanism of intervertebral disc degeneration has been investigated mainly in vitro but little in vivo, and gene expression analysis has been performed in a few studies. The cigarette smoking is a risk factor of low back pain. We developed a smoking box to create a rat model of intervertebral disc degeneration induced by passive cigarette smoking. Methods. Total RNA was extracted from intervertebral discs of rats that were raised in a cigarette-smoking box for 2 to 7 weeks. After synthesis of cDNA, the quantitative analysis of gene expression was performed by the real-time PCR. The remaining spines were subjected to the histologic examination. Results. Histologic changes of the nucleus pulposus and the anulus fibrosus were detected after 2 weeks of smoking and were frequently found after 7 weeks. Collagen genes were downregulated remarkably after 7 weeks of smoking. No significant increase was observed in the expressions of matrix metalloproteinase-3, but the expression of tissue inhibitor of metalloproteinases-1 started to increase at 4 weeks of smoking. Aggrecan also started to be up-regulated at 4 weeks. Conclusions. Changes in gene expression by passive cigarette smoking precede the histologic changes in the intervertebral discs. Reactions to suppress the destruction of tissue matrix and to regenerate the intervertebral discs are occurring at the same time as the degenerative histologic changes.

Clinical Course and Significance of the Clear Zone Around the Pedicle Screws in the Lumbar Degenerative Disease

Study Design. A retrospective study. Objective. To report the clinical course and significance of postoperative radiolucent zones around pedicle screws. Summary of Background Data. Radiolucent zones around pedicle screws have been considered to indicate loss of fixation, delayed union, or pseudarthrosis. Few reports have described the course and significance of them. Methods. Plain radiographs were evaluated from 190 patients with pedicle screw fixation. When 1 mm or greater circumferential lucency was confirmed around a screw on plain radiographs from 2 or more directions, the patient was judged as clear-zone positive. The course of clear-zone positivity was investigated and the relationships between clear-zone positivity and the following items were investigated: (1) number of levels fused, (2) bone union, (3) posterolateral lumbar fusion versus posterior lumbar interbody fusion, (4) clinical results, (5) bone mineral density, and (6) screw types. Results. Although clear zones were observed in 78 patients 6 months after surgery, the clear zone-positive rate decreased over time and the progression of bone union and the number of patients decreased to 28 at the final follow-up 3 years or more after surgery. Interobserver and intraobserver coefficient of variability in clear-zone judgment was over 0.86, and agreement was over 96%. At final follow-up, pseudarthrosis was found in 15 patients. Although the predictive value of the positive test for the presence of clear zones for pseudarthrosis at final follow-up was 0.50, sensitivity was 0.93 and specificity was 0.92. There were significant differences in the clear zone-positive rate in the number of levels fused and bone mineral density among the investigated items. Conclusion. As approximately two thirds of the clear zones disappeared over time, the presence of clear zones did not necessarily mean pseudarthrosis. However, clear zones persisting for 2 years or longer after surgery are a great risk of pseudarthrosis. Therefore, careful observation of clear zones around pedicle screws is of great significance as an evaluation of bone union.

Alteration of Gene Expression in Intervertebral Disc Degeneration of Passive Cigarette- Smoking Rats: Separate Quantitation in Separated Nucleus pulposus and Annulus fibrosus

Objective: We constructed a passive cigarette-smoking model with rats to investigate the molecular mechanism of intervertebral disc degeneration, and foundby gene expression analysis that passive cigarette smoking stimulated the stress-responsive signal pathway and inhibited the apoptotic pathway. In this study, to clarify that these changes were derived from either nucleus pulposus (NP) or annulus fibrosus (AF), we separately collected NP and AF and quantitatively analyzed gene expression. Methods: Total RNA was extracted from NP and AF of the lumbar intervertebral discs from rats which were kept in a smoking box for 4 and 8 weeks. Gene expression was measured by real-time PCR of cDNA synthesized from the total RNA. Results: Stress-responsive protein, heat shock protein 70, was expressed similarly in NP and AF, and wasupregulated to the same degree after 8 weeks of passive cigarette smoking. The protein tyrosine phosphatase gene was expressed more strongly in AF than in NP, and wasupregulated after 8 weeks of smoking in both tissueparts. The type II collagen and aggrecan genes were predominantly expressed in AF and NP, respectively. Conclusion: These results indicate that passive cigarette smoking stimulates both NP and AF, and induces the stress-responsible genes such as heat shock protein 70 and protein tyrosine phosphatase in both.

Vascular injury following microendoscopic lumbar discectomy treated with stent graft placement

The risk of great vessel injury is low in microendoscopic lumbar discectomy applied in a favorable visual field. However, it is important to be aware of the depth of the pituitary rongeur. In this article, the authors report the case of a 55-year-old woman with lumbar disc herniation who underwent microendoscopic discectomy and subsequently presented with an aneurysm and arteriovenous fistula located at the bifurcation of the right common iliac artery. The patient was treated with endoscopic placement of a stent graft and recovered uneventfully.

Analysis of the Relationship Between the Epidural Spinal Cord Compression (escc) Scale and Paralysis Caused by Metastatic Spine Tumors

Study Design. A retrospective, single-institute, and radiographic study. Objective. To evaluate the relationship between the epidural spinal cord compression (ESCC) scale and the severity of metastatic spine tumor–induced paralysis. Summary of Background Data. The ESCC scale is used to evaluate the grade of spinal cord compression on T2-weighted magnetic resonance imaging (MRI). However, few studies have investigated the relationship between such MRI findings and paralysis. Methods. The subjects were 467 patients with metastatic spine tumors and grade 1b or worse spinal cord compression according to the ESCC scale. Evaluations using this scale were performed by three spine surgeons, and results that were obtained by two or more surgeons were adopted. We also examined patients whose spinal cord compression deteriorated by one grade or more to American Spinal Injury Association (ASIA) grade C or worse within the first 3 weeks after MRI. Results. The kappa coefficients for inter- and intraexaminer variability were 0.90 and 0.95, respectively. ASIA grade D or worse paralysis developed in at least 50% of the patients with ESCC grade 1b or worse spinal cord compression at the C1-T2 and at least 50% of those with ESCC grade 1c or worse spinal cord compression at the T3-L5. The frequency of ASIA grade C or worse paralysis was high among the patients with ESCC grade 2 or worse spinal cord compression at the C7-L1. Nineteen patients experienced rapid deterioration of one grade or more to ASIA grade C or worse paralysis within the first 3 weeks after MRI. Of these, paralysis occurred in at least 30% of the patients with anterolateral or circumferential cord compression combined with ESCC grade 2 or 3 compression at the C7-L1. Conclusion. The severity of paralysis was not correlated with the ESCC scale. Patients with anterolateral or circumferential ESCC grade 2 or 3 cord compression at the C7-L1 are at high risk of rapidly progressive paralysis. Level of Evidence: 4

Treatment Outcome of Metastatic Spine Tumor in Lung Cancer Patients: Did the Treatments Improve Their Outcomes?

Study Design. A retrospective, single-center study. Objective. Investigation of the changes in the treatment outcomes of patients with lung cancer derived metastatic spine tumors. Summary of Background Data. Metastatic spine tumors derived from lung cancer had been progressive, and their prognosis is poor. It has recently been reported that the use of molecularly targeted drugs and bone-modifying agents (BMAs) improved the treatment outcomes of patients with lung cancer, but no detailed information about the treatment of metastatic spine tumors has been reported. Methods. Two hundred seven patients with lung cancer derived metastatic spine tumors who were examined after 2000 were analyzed. They were divided into 54 patients who were treated in or before 2005 (surgical treatment: 25 patients, conservative treatment: 29 patients) (group B) and 153 patients who were treated from 2006 onwards, when a molecularly targeted drug and BMA were introduced (surgical treatment: 24, conservative treatment: 129) (group A), and the treatment outcomes of the two groups were compared. Results. Significant differences in age and the affected vertebral level, paralysis grade, and Tokuhashi score (general condition, the number of vertebral metastases, and the total score) were detected between the groups. Regarding treatment outcomes, the mean duration of the post-treatment survival period was 5.1 and 9.3 months in groups B and A, respectively, that is, it was significantly longer in group A (P < 0.05). No significant intergroup difference in pain improvement was noted, and no significant post-treatment improvement in paralysis was achieved in either group. The post-treatment discharge-to-home eligibility rate did not differ significantly between the groups, but the Barthel Index improved significantly after treatment in group A (P < 0.05). Conclusion. After molecularly targeted drugs and BMA were introduced as treatments for lung cancer derived metastatic spine tumors, the survival periods of patients with such tumors increased, and their activity of daily living after treatment improved. Level of Evidence: 4

A novel pedicle screw with mobile connection: a pilot study.

To prevent adjacent disc problems after spinal fusion, a pedicle screw with a mobile junction between the head and threaded shaft was newly developed. The threaded shaft of the screw has 10 degrees mobility in all directions, but its structure is to prevent abnormal translation and tilting. This screw was evaluated as follows: (1) endurance test: 106 times rotational stress was applied; (2) biological reactions: novel screws with a mobile head and conventional screws with a fixed head were inserted into the bilateral pedicles of the L3, L4, and L5 in two mini pigs with combination. Eight months after surgery, vertebral units with the screw rod constructs were collected. After CT scan, the soft and bony tissues around the screws were examined grossly and histologically. As a result, none of the screws broke during the endurance test stressing. The mean amount of abrasion wear was 0.0338 g. In the resected mini pig section, though zygapophyseal joints between fixed-head screws showed bony union, the amount of callus in the zygapophyseal joints connected with mobile-head screws was small, and joint space was confirmed by CT. No metalloses were noted around any of the screws. Novel screws were suggested to be highly durable and histologically safe.

Prognostic factors in patients with metastatic spine tumors derived from lung cancer—a novel scoring system for predicting life expectancy

BackgroundRecently, molecule-targeting and bone-modifying agents have improved the treatment outcomes of lung cancer-derived metastatic spine tumors. Therefore, the prognostic factors for such tumors were examined, and novel scoring systems for predicting the life expectancy of patients with such tumors were proposed.MethodsIn 207 patients with lung cancer-derived metastatic spine tumors (surgery 49; conservative therapy 158), we retrospectively examined the factors that influenced the post-treatment survival time (age, sex, the affected site, pathology, general condition, the number of extraspinal bone metastases, the number of spinal metastases, the presence/absence of major internal organ metastasis, paralysis state, the total Tokuhashi score, the serum alkaline phosphatase level, the serum carcinoembryonic antigen level, molecule-targeting drug treatment, and bone-modifying agent treatment). Based on the results, we devised novel scoring systems for predicting the prognosis of such patients.ResultsUnivariate analyses showed that the pathology of the primary lung tumor, the patient’s general condition and paralysis state, and the presence/absence of molecule-targeting drug treatment significantly influenced survival. We performed a Cox regression analysis of these four factors and developed criteria for a novel scoring system based on the patient’s general condition and paralysis state, which exhibited significance in the regression analysis. A retrospective review indicated that the consistency rate between predicted life expectancy and actual survival was 67.3%. When criteria based on the four factors that exhibited significance in the univariate analyses were adopted, the consistency rate was 76.2%.ConclusionThe patient’s general condition and paralysis state, the pathology of the primary lung tumor, and molecule-targeting drug treatment influenced survival among patients with lung cancer-derived metastatic spine tumors. Novel scoring systems based on these four factors were proposed.

Efficacy of posterior decompression and fixation based on ossification-kyphosis angle criteria for multilevel ossification of the posterior longitudinal ligament in the thoracic spine

OBJECTIVE The range of decompression in posterior decompression and fixation for ossification of the posterior longitudinal ligament in the thoracic spine (T-OPLL) can be established using an index of spinal cord decompression based on the ossification-kyphosis angle (OKA) measured in the sagittal view on MRI. However, an appropriate OKA cannot be achieved in some cases, and posterior fixation is applied in cases with insufficient decompression. Moreover, it is unclear whether spinal cord decompression of the ventral side is essential for the treatment of OPLL. In this retrospective analysis, the efficacy of posterior decompression and fixation performed for T-OPLL was investigated after the range of posterior decompression had been set using the OKA. METHODS The MRI-based OKA is the angle from the superior margin at the cranial vertebral body of the decompression site and from the lower posterior margin at the caudal vertebral body of the decompression site to the prominence of the maximum OPLL. Posterior decompression and fixation were performed in 20 patients. The decompression range was set so that the OKA was ≤ 23° or the minimum if this value could not be achieved. Cases in which an OKA ≤ 23° could and could not be achieved were designated as groups U (13 patients) and O (7 patients), respectively. The mean patient ages were 50.5 and 62.1 years (p = 0.03) and the mean preoperative Japanese Orthopaedic Association (JOA) scores were 5.9 and 6.0 (p = 0.9) in groups U and O, respectively. The postoperative JOA score, rate of improvement of the JOA score, number of levels fused, number of decompression levels, presence of an echo-free space during surgery, operative time, intraoperative blood loss, and perioperative complications were examined. RESULTS In groups U and O, the mean rates of improvement in the JOA score were 50.0% and 45.6% (p = 0.3), the numbers of levels fused were 6.7 and 6.4 (p = 0.8), the numbers of decompression levels were 5.9 and 7.4 (p = 0.3), an echo-free space was noted during surgery in 92.3% and 42.9% of cases (p = 0.03), the operative times were 292 and 238 minutes (p = 0.3), and the intraoperative blood losses were 422 and 649 ml (p = 0.7), and transient aggravation of paralysis occurred as a perioperative complication in 2 and 1 patient, respectively. CONCLUSIONS There was no significant difference with regard to the recovery rate of the JOA score between patients with (group U) and without (group O) sufficient spinal cord decompression. The first-line surgical procedure of posterior decompression and fixation with the range of posterior decompression set as an OKA ≤ 23° before surgery involves less risk of postoperative aggravation of paralysis and may result in a better outcome.