Kazuya Nishizawa

Prevalence, distribution, and morphology of thoracic ossification of the yellow ligament in Japanese: results of CT-based cross-sectional study.

Study Design. A cross-sectional study. Objective. To gain an insight for the prevalence, morphology, and distribution of thoracic ossification of the yellow ligament (OYL) by computed tomography (CT) and review of the literature. Summary of Background Data. The epidemiology and etiology of OYL remains obscure. To date, to the best of our knowledge, there is no study that comprehensively evaluated thoracic spine by CT to assess the prevalence, distribution, and morphology of OYL in a large enough sample size with wide age distribution. Methods. The participants of this study were the patients who have undergone chest CT for the examination of pulmonary diseases in our institute. The patients with previous thoracic spine surgery and younger than 15 years were excluded. Prevalence, distribution, and morphology of thoracic OYL were reviewed. Results. A total of 3013 patients (1261 females and 1752 males) with the mean age of 65 years were recruited. The CT-based evidence of OYL was noted in 1094 (428 females and 666 males) individuals (36%). Single-level involvement was noted in 532 cases, whereas 562 individuals presented multilevel involvement. Statistical analyses revealed that OYL was noted at a significantly higher rate among the males (P = 0.022). Of a total of 2051 OYLs, 779 central type OYLs, a mushroom-shaped ossification localized at the center of laminae, and 1272 noncentral type OYLs were noted. Distribution of the thoracic OYL formed 2 peaks with the highest and second highest peak found at T10–T11 and T4–T5, respectively. Interestingly, OYL is noted at consistent rates after the age of 30; however, its size increased in age-dependent manners. Conclusion. The prevalence of thoracic OYL in Japanese was 36%. A further study disclosing the association between clinical manifestations and size and/or morphology of OYL is warranted. Level of Evidence: N/A

Prevalence, distribution, and morphology of thoracic ossification of the posterior longitudinal ligament in Japanese: results of CT-based cross-sectional study.

Study Design. A cross-sectional study. Objective. To gain an insight into the prevalence, morphology, and distribution of thoracic ossification of the posterior longitudinal ligament of the spine (T-OPLL) by computed tomography (CT) and review of the literature. Summary of Background Data. The epidemiology and cause of T-OPLL remains obscure. To date, to the best of our knowledge, there is no study that has comprehensively evaluated the thoracic spine by CT to assess the prevalence, distribution, and morphology of T-OPLL in a sufficiently large size of sample with wide distribution of age. Methods. The participants of this study were the patients who have undergone chest CT for the examination of pulmonary diseases in our institute. The patients with previous thoracic spine surgery and younger than 15 years were excluded. Prevalence, distribution, and morphology of T-OPLL were reviewed. Results. A total of 3013 patients (1261 females and 1752 males) with the mean age of 65 years were recruited. The CT-based evidence of T-OPLL was noted in 56 (38 females and 18 males) individuals (1.9%). Most frequently encountered type was liner type, followed by continuous cylindrical type and mixed type. Continuous waveform and beaked type were less frequently encountered. Statistical analyses revealed that T-OPLL was noted at a significantly higher rate among the females. The mean age of T-OPLL–positive males was significantly higher than that of T-OPLL–negative males. Furthermore, there was significant difference of body mass index between T-OPLL–positive and T-OPLL–negative individuals. Most of T-OPLLs were confirmed in higher or middle thoracic regions and the highest peak was found at T3–T4. T-OPLL was noted after the age of 40 years with the peak distribution found at the age of 60 years. Conclusion. The prevalence of T-OPLL in Japanese was 1.9%. Further studies that characterize definitive subtypes of T-OPLL on CT are warranted so as to establish possible association between clinical manifestations and size and/or subtypes of T-OPLL. Level of Evidence: N/A

Short-Term Clinical Result of Cortical Bone Trajectory Technique for the Treatment of Degenerative Lumbar Spondylolisthesis with More than 1-Year Follow-Up

Study Design Retrospective follow-up study on the result of surgical treatment for patients with degenerative lumbar spondylolisthesis (DLS) using cortical bone trajectory (CBT) technique. Purpose To evaluate the capability of CBT to manage patients with DLS. Overview of Literature CBT is a recently advocated, novel, less-invasive technique of lumbar pedicle screw, which provides enhanced screw purchase by maximizing the thread contact with higher density bone surface. Despite the frequent use of CBT technique in the lumbar spine surgery, little is known of the capability of this technique to manage patients with DLS. Methods Thirty two consecutive patients (5 males, 27 females) surgically treated with single-level DLS in our institute using CBT were included. All patients were followed up at least 12 months (mean 24 months). Their clinical and radiological features were measured. Results Good leg pain relief was achieved in all patients. The mean postoperative percentage slip demonstrated significant reduction with significant neurological recovery when compared with preoperative percentage slip, and it was maintained until the latest follow-up. Loss of correction of more than 3 mm during the follow-up period was observed in 3 cases. Surgical site infection was observed in one case; however, pull-out of PSs or neurological deterioration was not found. No patient needed additional surgery during the follow-up period. Conclusions These preliminary results confirmed that CBT is useful for the treatment for patients with DLS. This technique allows good reduction of spondylolisthesis and neurological improvement.

Improved quality of cartilage repair by bone marrow mesenchymal stem cells for treatment of an osteochondral defect in a cynomolgus macaque model

Background and purpose — Integration of repaired cartilage with surrounding native cartilage is a major challenge for successful tissue-engineering strategies of cartilage repair. We investigated whether incorporation of mesenchymal stem cells (MSCs) into the collagen scaffold improves integration and repair of cartilage defects in a cynomolgus macaque model. Methods — Cynomolgus macaque bone marrow-derived MSCs were isolated and incorporated into type-I collagen gel. Full-thickness osteochondral defects (3 mm in diameter, 5 mm in depth) were created in the patellar groove of 36 knees of 18 macaques and were either left untreated (null group, n = 12), had collagen gel alone inserted (gel group, n = 12), or had collagen gel incorporating MSCs inserted (MSC group, n = 12). After 6, 12, and 24 weeks, the cartilage integration and tissue response were evaluated macroscopically and histologically (4 null, 4 gel, and 4 MSC knees at each time point). Results — The gel group showed most cartilage-rich reparative tissue covering the defect, owing to formation of excessive cartilage extruding though the insufficient subchondral bone. Despite the fact that a lower amount of new cartilage was produced, the MSC group had better-quality cartilage with regular surface, seamless integration with neighboring naïve cartilage, and reconstruction of trabecular subchondral bone. Interpretation — Even with intensive investigation, MSC-based cell therapy has not yet been established in experimental cartilage repair. Our model using cynomolgus macaques had optimized conditions, and the method using MSCs is superior to other experimental settings, allowing the possibility that the procedure might be introduced to future clinical practice.

Spatiotemporal control of proliferation and differentiation of bone marrow–derived mesenchymal stem cells recruited using collagen hydrogel for repair of articular cartilage defects

Articular cartilage has a poor healing capacity, and cartilage regeneration is not always warranted to achieve healing. On the other hand, collagen scaffolds have been shown to support regeneration of articular cartilage defects in animal models, whereas bone morphogenetic protein-2 (BMP-2) is known to cause chondrogenic differentiation of marrow-derived mesenchymal stem cells (MSCs). The purpose of this study was to evaluate the effectiveness of intra-articular administration of BMP-2 into bone marrow-derived MSCs recruited to defects using original collagen hydrogel in rabbits at various time points. Full-thickness defects were created in both knees, then collagen hydrogels were transplanted, and BMP-2 was supplied for 1-week periods, as follows. BMP-2 was administered immediately after the operation for 1 week (BMP0-1 group), and BMP-2 was administered between weeks 1 and 2 after the operation (BMP1-2 group). BMP2 was administered between weeks 2 and 3 (BMP2-3 group). Specimens were then obtained, and bromodeoxyuridine (BrdU)-positive cells were enumerated and histologic grading was also performed. In addition, the gene expression analysis was performed using quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) assays. Enumeration of BrdU-positive cells showed a significant increase in the BMP0-1 group compared with the other groups. Similarly, histologic scores in the BMP0-1 group were superior for up to 8 weeks. Finally, RT-PCR findings revealed that immediate BMP-2 administration enhanced chondrogenic differentiation.

Prevalence of thoracic diffuse idiopathic skeletal hyperostosis (DISH) in Japanese: Results of chest CT-based cross-sectional study

BACKGROUND The epidemiology and etiology of diffuse idiopathic skeletal hyperostosis (DISH) remain obscure. To date, to the best of our knowledge, there is no study that precisely evaluated the prevalence of thoracic DISH based on computed tomography (CT) data in large number of non-operated cohort with wide age distribution. METHODS The participants of this study were the consecutive patients who have undergone chest CT for the examination of pulmonary diseases in our institute. The patients with previous thoracic spine surgery and younger than 15 years old were excluded. Chest CT data were reconstructed in the condition suitable for bone evaluation by the software application. Definitive diagnosis of DISH was determined according to the criteria established by Resnick and Niwayama. Prevalence and distribution of thoracic DISH were reviewed and the data was statistically analyzed. RESULTS Total 3013 patients (1261 females and 1752 males) with the mean age of 65 years were recruited. The CT-based evidence of thoracic DISH was noted in 261 individuals (31 females and 230 males) (8.7%), and their mean age was 73 years. Statistical analyses revealed that thoracic DISH had a significant male preponderance. The mean age of thoracic DISH positive individuals was significantly higher than that of thoracic DISH negative individuals. There was significant difference of bone mass index (BMI) between thoracic DISH positive and negative individuals. Thoracic DISH was noted after the age of 40s with the highest distribution found at the age of 70s. No thoracic DISH localizes only higher thoracic region was found. CONCLUSIONS The CT-based prevalence of thoracic DISH in Japanese was 8.7%. Thoracic DISH has a significant predisposition to elderly male with high BMI.

Long-term clinical outcome of sacral chondrosarcoma treated by total en bloc sacrectomy and reconstruction of lumbosacral and pelvic ring using intraoperative extracorporeal irradiated autologous tumor-bearing sacrum: a case report with 10 years follow-up

BACKGROUND CONTEXT Primary malignant tumors of the sacrum are rare. Chondrosarcoma is one of the common malignant tumors arising from the sacrum. Chondrosarcoma is often invasive, and there is a high propensity for local recurrence. Surgical resection is often the only effective treatment; however, the treatment of malignant sacral tumors can be challenging, both because of the anatomy of the spinopelvic complex and the frequently large tumor size. PURPOSE We report a case of sacral chondrosarcoma that was successfully treated by total en bloc sacrectomy and reconstruction of the lumbosacral and pelvic ring using intraoperative extracorporeal irradiated autologous tumor-bearing sacrum. STUDY DESIGN A case report with 10 years follow-up. METHODS A 51-year-old man presented with right lower leg pain. Plain radiographs and computed tomography (CT) showed an osteolytic lesion at the sacrum that extended to the sacroiliac joint. Magnetic resonance imaging demonstrated that the tumor mass was localized from S1 to S2 with an epidural lesion at L5-S1 disc level. Histopathologic evaluation by open biopsy revealed that the lesion was chondrosarcoma. Total en bloc sacrectomy of the tumor-bearing sacrum was performed. The removed tumor-bearing sacrum was extracorporeally irradiated at 200 Gy during the operation and returned to the original position as a bone graft and fixed with instruments thereafter. RESULTS We needed two revision surgeries during the first 3 years because of the implant failures; however, 10 years after the initial surgery, CT revealed that the irradiated sacrum had remodeled into living bone and integrated with surrounding iliac bone without radiological evidence of tumor recurrence. The patient ambulates without any support and there was no clinical and radiological evidence of tumor recurrence. CONCLUSIONS The advantages of our method include the availability of high dose of radiation because of extracorporeal irradiation, excellent fit between graft and host bone, reduction of the dead space, no immunological rejection, no need for a bone bank, availability of the sacrum not only for the augmentation of the large defect but also for the scaffold for the other bone grafts. Our report is of only one case; however, we consider that it could be one option for the treatment of sacral malignant bone tumors, such as chondrosarcoma.

Plexiform schwannoma arising from cauda equina.

A 61-year-old woman with rheumatoid arthritis (RA) presented with unprecedented progressive low back and bilateral lower leg dull-pain. She has a 10-year and 7year history of methotrexate and etanercept treatment for RA, respectively. Physical examination revealed the absence of neurologic compromise. There was no evidence of any skin pigmentation and familial history of neurogenic tumors. Plain radiographs of the lumbar spine revealed degenerative changes, especially at L2/L3 level (Fig. 1). The plain magnetic resonance imaging (MRI) revealed intradural low-intensity lesion on both T1and T2-weighted images (Fig. 2, Left and Middle); however, which may have been overlooked without gadoliniumenhanced MRI (Gd-MRI). The succeeding Gd-MRI of lumbar spine clearly revealed a homogeneously enhanced intradural lesion that extended from L2 to L4 (Fig. 2, Right). Computed tomography revealed neither calcification of the lesion nor bone scalloping (data not shown). Taking all these findings including being under treatment

Novel Landmark for Cervical Pedicle Screw Insertion Point from Computed Tomography-Based Study

Study Design Cross-sectional study. Purpose The purpose of this study was to evaluate a novel landmark for the cervical pedicle screw insertion point. Overview of Literature To improve the accuracy of pedicle screw placement, several studies have employed the lateral mass, lateral vertical notch, and/or inferior articular process as landmarks; however, we often encounter patients in whom we cannot identify accurate insertion points for pedicle screws using these landmarks because of degenerative changes in the facet joints. The superomedial edge of the lamina is less affected by degenerative changes, and we hypothesized that it could be a new landmark for identifying an accurate cervical pedicle screw insertion point. Methods A total of 327 consecutive patients, who had undergone neck computed tomographic scanning for determination of neck disease in our institute, were included in the study. At first, the line was drawn parallel to the superior border of the pedicle in the sagittal plane and parallel to the vertical body in the coronal plane. The line was moved downward in 1-mm increments to the inferior border of the pedicle. We determined whether the line passing through the superomedial edge of the lamina (termed the “N-line”) was located between the superior and inferior borders of the pedicle in the sagittal plane. Results The percentages of N-lines located between the superior and inferior borders of the pedicle were 100% at C3, 100% at C4, 99% at C5, 96% at C6, and 97% at C7. The lower cervical spine has the higher N-line location. Conclusions The N-line was frequently located at the level of the pedicle of each cervical spine in the sagittal plane. The superomedial edge of the lamina could be a new landmark for the insertion point of the cervical pedicle screw.

Prevalence and clinical features of sports-related lumbosacral stress injuries in the young

BackgroundStress injuries (stress fractures and stress reactions) of the lumbosacral region are one of the causes of sports-related lower back pain in young individuals. These injuries can be detected by bone marrow edema lesion on MRI. However, little is known about the prevalence and clinical features of early stage lumbosacral stress injuries. This study aimed to evaluate the epidemiology of lumbosacral stress injuries.MethodsA total of 312 patients (under 18 years of age) who complained of sports-related lower back pain that had lasted for ≥7 days underwent magnetic resonance imaging (MRI) scans. We reviewed patients’ records retrospectively.ResultsMRI showed that 33.0% of the patients had lumbar stress injuries and 1.6% had sacral stress injuries. Lumbar stress injuries were more common in males than in females and were found in 30% of 13- to 18-year-old patients. About 50% of the patients that participated in soccer or track and field were diagnosed with lumbar stress injuries. No clinical patterns in the frequencies of sacral stress injuries were detected due to the low number of patients that suffered this type of injury. Plain radiography is rarely able to detect the early stage lesions associated with lumbosacral stress injuries, but such lesions can be detected in the caudal–ventral region of the pars interarticularis on sagittal computed tomography scans.SummaryThirty-three percent of young patients that complained of sports-related lower back pain for ≥7 days had lumbar stress injuries, while 1.6% of them had sacral stress injuries. Clinicians should be aware of the existence of these injuries. MRI is useful for diagnosing lumbosacral stress injuries.