Clinical features and outcomes of spine surgery in patients with ankylosing spondylitis.

OBJECTIVES: The study aimed to comprehend the clinical features and outcomes of surgical treatments for spinal disorders in patients with ankylosing spondylitis. METHODS: This retrospective study enrolled patients with ankylosing spondylitis who underwent spine surgery between 2000 and 2019 in our facility. RESULTS: Thirteen patients with ankylosing spondylitis underwent spine surgeries. The mean age was 56.2 years, and the mean disease duration was 25.1 years at the time of surgery. Nine patients had vertebral fracture, two had kyphotic deformity, and two had myelopathy due to the spinal ligament ossification. Fracture cases included five patients with secondary pseudarthrosis/delayed palsy due to conservative treatment failure. Spinal fixation was performed in all patients. Pedicle subtraction osteotomy for kyphosis and laminectomy for myelopathy were also conducted. All patients improved after surgeries. One patient with kyphotic deformity underwent additional surgery of bilateral hip prosthesis, which resulted in better spine alignment. Four cases of perioperative complications were observed. CONCLUSION: Myelopathy was newly found as the aetiology requiring surgery in patients with ankylosing spondylitis. This summarized case series could help physicians to identify patients with surgically treatable spinal disorders among patients with ankylosing spondylitis.

Isolated trochlea osteochondral fracture of the distal humerus in a 6-year-old patient surgically fixed using biodegradable pins: A case study with over 3 years of follow-up.

Isolated humeral trochlea fracture, particularly in skeletally immature children, is extremely rare. The exact mechanism of this injury remains unknown because the humeral trochlea is embraced within the olecranon fossa without any muscular or ligamentous attachment. We report the treatment of a 6-year-old boy who sustained an isolated trochlea osteochondral fracture when he fell with his elbow in a flexed position while skateboarding. The patient had a history of lateral condyle fracture of the ipsilateral humerus one year previously. At the diagnosis, computed tomography (CT) revealed a small bony fragment displaced anteromedially from the superior border of the trochlea with lifting of its lateral border. Ultrasonography confirmed instability of the fractured segment. At the time of surgery, the anterior trochlea surface fracture formed a hinged fracture line on its proximal and medial border. The fracture was anatomically reduced and fixed using biodegradable pins. Postoperatively, the involved elbow showed a sufficient functional recovery to a normal level without complications during 3 years of observation, although the biodegradable pins remained radiographically in place with partial degradation. The laterally opened avulsed fragment on primary CT clearly depicted the mechanism of injury: the impact entered from the lateral side of the elbow and progressed from the longitudinal ridge of the coronoid process onto the sulcus of the trochlea to shear off the anteromedial portion of the trochlea in a medial direction. The use of biodegradable pins for fixing a trochlea fracture in a skeletally immature patient provided favorable fracture healing; however, close observation is necessary until the completion of skeletal growth because of the lack of sufficient information on the long-term prognosis of trochlea fracture, especially when treated using biodegradable implants.

Long-term outcomes of spinal meningioma resection with outer layer of dura preservation technique.

Spinal meningioma is a common benign intradural spinal tumor. It has been reported that the local recurrence rate after surgical resection increases with longer follow-up duration. Simpson grade 1 resection could reduce the risk of recurrence, but this procedure needs dural reconstruction, which would cause cerebrospinal fluid (CSF) leakage or iatrogenic spinal cord injury. Saito et al. reported dura preservation technique to reduce the risk of CSF leakage, in which the meningioma together with the inner layer of the dura is removed and the outer layer is preserved for simple dural closure. The long-term outcomes with this technique have never been investigated. In this study, we retrospectively analyzed the data of 38 surgically treated patients (dura preservation technique, 12 patients; Simpson grade 2 resection, 26 patients) to assess the long-term recurrence rate (mean, 121.5 months; range, 60-228 months). The local recurrence rate in the dura preservation group was 8.3% (1 of 12 cases), which was similar to that in Simpson grade 2 resection group (2 of 26 cases [7.7%]). Although this case series did not indicate the significant difference in the recurrence rates between the dura preservation group and Simpson grade 2 group, we consider that this technique still has advantages for surgically less invasiveness in terms of dural reconstruction which is necessary for Simpson grade 1 and higher possibility of complete resection of tumors compared with Simpson grade 2 resection.

Use of an inertial measurement unit sensor in pedicle screw placement improves trajectory accuracy.

Ascertaining the accuracy of the pedicle screw (PS) trajectories is important as PS malpositioning can cause critical complications. We aimed to determine the angle range over which estimation is unreliable; build a low-cost PS placement support system that uses an inertial measurement unit (IMU) to enable the monitoring of surgical tools and PS trajectories, and determine the situations where IMU support would be most beneficial. In PS insertion experiments, we used cadaver samples that included lumbar porcine spines. Computed tomography images obtained before and after PS insertion were viewed. Offsets between the planned and implanted PS trajectories in the freehand and IMU-assisted groups were analyzed. The PS cortical bone breaches were classified according to the Gertzbein and Robbins criteria (GRC). Added head-down tilted sample experiments were repeated wherein we expected a decreased rostro-caudal rotational accuracy of the PS according to the angle estimation ability results. Evaluation of the PS trajectory accuracy revealed no significant advantage of IMU-assisted rostro-caudal rotational accuracy versus freehand accuracy. According to the GRC, IMU assistance significantly increased the rate of clinically acceptable PS positions (RoCA) than the freehand technique. In the head-down tilted sample experiments, IMU assist provided increased accuracies with both rostro-caudal and medial rotational techniques when compared with the freehand technique. In the freehand group, RoCA was significantly decreased in samples with rostral tilting relative to that in the samples without. However, In the IMU-assisted group, no significant difference in RoCA between the samples with and without head-down tilting was observed. Even when the planned PS medial and/or rostro-caudal rotational angle was relatively large and difficult to reproduce manually, IMU-support helped maintain the PS trajectory accuracy and positioning safety. IMU assist in PS placement was more beneficial, especially for larger rostro-caudal and/or medial rotational pedicle angles.

GRK5 Inhibition Attenuates Cartilage Degradation via Decreased NF-κB Signaling.

OBJECTIVE: NF-κB-dependent signaling is an important modulator in osteoarthritis (OA), and G protein-coupled receptor kinase 5 (GRK5) regulates the NF-κB pathway. This study was undertaken to investigate the functional involvement of GRK5 in OA pathogenesis. METHODS: GRK5 expression in normal and OA human knee joints was analyzed immunohistochemically. Gain- or loss-of-function experiments were performed using human and mouse chondrocytes. OA was induced in GRK5-knockout mice by destabilization of the medial meniscus, and histologic examination was performed. OA was also induced in wild-type mice, which were then treated with an intraarticular injection of amlexanox, a selective GRK5 inhibitor, every 5 days for 8 weeks. RESULTS: GRK5 protein expression was increased in human OA cartilage. In vitro, expression levels of OA-related factors and NF-κB transcriptional activation were down-regulated by suppression of the GRK5 gene in human OA chondrocytes (3.49-fold decrease in IL6 [P < 0.01], 2.43-fold decrease in MMP13 [P < 0.01], and 2.66-fold decrease in ADAMTS4 [P < 0.01]). Conversely, GRK5 overexpression significantly increased the expression of OA-related catabolic mediators and NF-κB transcriptional activation. On Western blot analysis, GRK5 deletion reduced IκBα phosphorylation (up to 4.4-fold decrease [P < 0.05]) and decreased p65 nuclear translocation (up to 6.4-fold decrease [P < 0.01]) in mouse chondrocytes. In vivo, both GRK5 deletion and intraarticular amlexanox protected mouse cartilage against OA. CONCLUSION: Our results suggest that GRK5 regulates cartilage degradation through a catabolic response mediated by NF-κB signaling, and is a potential target for OA treatment. Furthermore, amlexanox may be a major compound in relevant drugs.

Surgery-related predictable risk factors influencing postoperative clinical outcomes for thoracic myelopathy caused by ossification of the posterior longitudinal ligament: a multicenter retrospective study.

OBJECTIVE: Compression of the spinal cord by thoracic ossification of the posterior longitudinal ligament (T-OPLL) often causes severe thoracic myelopathy. Although surgery is the most effective treatment for T-OPLL, problems associated with surgical intervention require resolution because surgical outcomes are not always favorable, and a small number of patients experience deterioration of their neurological status after surgery. The aim of the present study was to examine the surgery-related risk factors contributing to poor clinical outcomes for myelopathy caused by T-OPLL. METHODS: Data were extracted from the records of 55 patients with thoracic myelopathy due to T-OPLL at institutions in the Fukuoka Spine Group. The mean follow-up period was 5.3 years. Surgical outcomes were assessed using the Japanese Orthopaedic Association (JOA) scale. To investigate the definitive factors associated with surgical outcomes, univariate and multivariate regression analyses were performed with several patient-related and surgery-related factors, including preoperative comorbidities, radiological findings, JOA score, surgical methods, surgical outcomes, and complications. RESULTS: Neurological status improved in 33 patients (60.0%) and deteriorated in 10 patients (18.2%) after surgery. The use of instrumentation was significantly associated with an improved outcome. In the comparison of surgical approaches, posterior decompression and fusion resulted in a significantly higher neurological recovery rate than did anterior decompression via a posterior approach and fusion or decompression alone. It was also found that postoperative neurological status was significantly poorer when there were fewer instrumented spinal levels than decompression levels. CSF leakage was a predictable risk factor for deterioration following surgery. CONCLUSIONS: It is important to identify preventable risk factors for poor surgical outcomes for T-OPLL. The findings of the present study suggest that intraoperative CSF leakage and a lower number of instrumented spinal fusion levels than decompression levels were exacerbating factors for the neurological improvement in T-OPLL surgery.

FOXO1 transcription factor regulates chondrogenic differentiation through transforming growth factor ß1 signaling.

The forkhead box O (FOXO) proteins are transcription factors involved in the differentiation of many cell types. Type II collagen (Col2) Cre-Foxo1-knockout and Col2-Cre-Foxo1,3,4 triple-knockout mice exhibit growth plate malformation. Moreover, recent studies have reported that in some cells, the expressions and activities of FOXOs are promoted by transforming growth factor ß1 (TGFß1), a growth factor playing a key role in chondrogenic differentiation. Here, using a murine chondrogenic cell line (ATDC5), mouse embryos, and human mesenchymal stem cells, we report the mechanisms by which FOXOs affect chondrogenic differentiation. FOXO1 expression increased along with chondrogenic differentiation, and FOXO1 inhibition suppressed chondrogenic differentiation. TGFß1/SMAD signaling promoted expression and activity of FOXO1. In ATDC5, FOXO1 knockdown suppressed expression of sex-determining region Y box 9 (Sox9), a master regulator of chondrogenic differentiation, resulting in decreased collagen type II α1 (Col2a1) and aggrecan (Acan) expression after TGFß1 treatment. On the other hand, chemical FOXO1 inhibition suppressed Col2a1 and Acan expression without suppressing Sox9 To investigate the effects of FOXO1 on chondrogenic differentiation independently of SOX9, we examined FOXO1's effects on the cell cycle. FOXO1 inhibition suppressed expression of p21 and cell-cycle arrest in G0/G1 phase. Conversely, FOXO1 overexpression promoted expression of p21 and cell-cycle arrest. FOXO1 inhibition suppressed expression of nascent p21 RNA by TGFß1, and FOXO1 bound the p21 promoter. p21 inhibition suppressed expression of Col2a1 and Acan during chondrogenic differentiation. These results suggest that FOXO1 is necessary for not only SOX9 expression, but also cell-cycle arrest during chondrogenic differentiation via TGFß1 signaling.

Prone position surgery for a professional sumo wrestler with thoracic ossification of the posterior longitudinal ligament resulting in intraoperative brachial plexus injury by hypertrophic pectoral muscles.

Surgery in the prone position is associated with a variety of complications due to the positioning, including the widely recognized peripheral nerve compression injuries and brachial plexus neuropathy. Previous studies have reported that thin body habitus is a predisposing risk factor for the compressive peripheral nerve injuries due to the prone position surgery. However, prone-position-related brachial plexus injury in patients who are overweight due to hypertrophic muscles have never been reported. Here we report a case of a professional sumo wrestler with severe thoracic ossification of the posterior longitudinal ligament (OPLL). Thoracic OPLL was successfully treated by posterior spinal fusion and decompression surgery. Despite a preoperative simulation and intraoperative inspection of the patient's surgical positioning, he suffered from bilateral upper extremity paralysis immediately after the surgery. Postoperative axillary MRI image revealed a high-intensity area on both sides of his pectoral muscles and axillary fossa, which implied that the pectoral muscles between the ribs and chest pad were pushed out toward the axillary fossa, resulting in compressive brachial plexus injury. His upper extremity motor paralysis was fully recovered in 6 months, but he still has mild tingling sensation even after 12 months of his surgery. In conclusion, overweight patients with hypertrophic muscles pose a risk for brachial plexus entrapment injury by pectoral muscles during prone-position surgery, and therefore it would be more effective to use a wide chest pad to reduce the pressure on the pectoral muscles to prevent it from being pushed out toward the axillary fossa.

Which Side-Bending X-ray Position is Better to Evaluate the Preoperative Curve Flexibility in Adolescent Idiopathic Scoliosis Patients, Supine or Prone?

STUDY DESIGN: Prospective cohort study. PURPOSE: The present study aimed to evaluate the difference in the preoperative curve flexibility between the supine and prone positions in patients with adolescent idiopathic scoliosis (AIS). OVERVIEW OF LITERATURE: In AIS, a side-bending view is necessary to differentiate a structural curve from a nonstructural curve using the Lenke classification system. However, there are no published studies about which position, supine or prone, is more effective when evaluating preoperative curve flexibility using side-bending X-ray images in AIS patients. METHODS: Radiographs were analyzed for 32 AIS patients (26 females, six males) who underwent posterior correction and fusion of their main thoracic (MT) curves. Cobb angles of MT, proximal thoracic (PT), and thoracolumbar/lumbar (TL/L) curves were measured preoperatively using upright, supine (anteroposterior and side-bending), and prone (posteroanterior and side-bending) X-rays. RESULTS: The average Cobb angles of PT, MT, and TL/L curves on preoperative upright/supine/prone X-rays were 29.1°/26.7°/26.6°, 60.7°/48.5°/48.2°, and 41.0°/32.6°/33.1°, respectively. The average Cobb angles of PT, MT, and TL/L curves on supine/prone sidebending X-rays were 19.2°/20.3°, 36.3°/36.4°, and 13.9°/15.7°, respectively. The flexibility rates of PT, MT, and TL/L curves in supine/prone positions were 35.3%/32.5%, 40.6%/40.2%, and 71.7%/68.2%, respectively. Comparing flexibility rates in the prone position with those in the supine position in each case, the average ratios of PT, MT, and TL/L curves were found to be 1.0, 1.0, and 0.9, respectively. There were no statistically significant differences between supine and prone side-bending X-ray measurements. However, the Lenke classification in six of 32 patients (18.8%) differed between supine and prone positions because the TL/L curve in the supine position was slightly more flexible than in the prone position. CONCLUSIONS: Supine side-bending films may be suitable for the evaluation of preoperative curve flexibility in AIS, especially for lumbar modifier C.

Effect of cartilaginous endplates on extruded disc resorption in lumbar disc herniation.

OBJECTIVE: The aim of this study was to investigate the clinicopathologic features of lumbar disc herniation (LDH) with endplate degeneration and the association between cartilaginous fragments and inflammatory response to the herniated disc. SUMMARY OF BACKGROUND DATA: LDH often involves hyaline cartilage fragments pulled from the vertebral endplates. Modic changes are closely associated with LDH that contains hyaline cartilage, and cartilaginous endplates seem to affect resorption of the herniated disc. METHODS: A total of 78 patients who underwent microscopic discectomy between 9 and 16 weeks after an occurrence of LDH were reviewed. Modic changes, disc degeneration, high-intensity zone, and vertebral corner defect were evaluated using magnetic resonance imaging (MRI). Histopathological observations of cartilaginous endplates and inflamed granulation tissue in the herniated disc were made. In cases with inflamed granulation tissue, neovascularization and macrophage infiltration were also evaluated using immunohistochemical analysis. RESULTS: Modic changes were observed in approximately one-third of the patients (26 cases: type 1, 7; type 2, 17; and type 3, 2). Cartilaginous endplates were observed in 32 cases (41%) and in the majority of cases with Modic changes compared with cases without Modic changes (65%, p = 0.001). Although inflamed granulation tissue was observed in 60 cases (77%), no significant differences were detected in patient age and the composition of the herniated material. Immunohistochemical analysis showed that fewer CD34-positive capillaries and CD68-positive cells were found in cases with cartilaginous fragments compared with those without cartilaginous fragments (p < 0.001). In addition, a higher immunoreactivity to CD34 and CD68 was found in herniated discs <25% of whose area was occupied by cartilaginous endplates compared with discs whose area was occupied at 25% or more (p < 0.001). CONCLUSION: There is an association between LDH with endplate degeneration and cartilaginous herniation, with Modic type 2 predominating. Furthermore, neovascularization and macrophage infiltration, especially if the amount of cartilage is high, are likely to be less frequent in cartilaginous herniation, leading to failure in the spontaneous remission of clinical symptoms.

The neurological outcome of radiotherapy versus surgery in patients with metastatic spinal cord compression presenting with myelopathy.

PURPOSE: While radiotherapy is generally an acceptable treatment for metastatic spinal cord compression, surgical intervention is controversial due to the invasiveness and diversity of diseases in the patients being considered. The ideal treatment, therefore, depends on the situation, and the most acute treatment possible is necessary in patients presenting with myelopathy. We compared the neurological outcomes between radiotherapy and surgery in patients with metastatic spinal cord compression presenting with myelopathy. METHODS: A total 54 patients with metastatic spinal cord compression presenting with myelopathy treated in our institution between 2006 and 2016 were analyzed retrospectively. Twenty patients were selected by radiotherapy alone (radiation group), and 36 patients were selected by decompression and stabilization surgery with or without radiotherapy (surgery group). The neurological outcomes and complications were compared between the two treatment groups. RESULTS: Seven patients initially in the radiation group underwent surgery because of a substantial decline in their motor strength during radiotherapy. One of the remaining 13 patients (8%) in the radiation group and 30 of the 34 patients (88%) in the surgery group showed improvement in their neurological symptoms (P < 0.01). One patient (8%) in the radiation group and 21 patients (62%) in the surgery group were ambulatory after treatment (P < 0.01). There were no major complications related to radiotherapy, but surgery-related complications occurred in 9 of 34 (26%) patients, and 6 (18%) patients needed reoperation. CONCLUSIONS: Surgical decompression and stabilization may be required to improve the neurological function in patients with metastatic spinal cord compression presenting with myelopathy. However, the high rate of complications associated with surgery should be taken into consideration.

Clinical Outcome and Prognostic Factors of Malignant Spinal Dumbbell Tumors.

INTRODUCTION: To investigate the clinical outcome and prognostic factors of malignant spinal dumbbell tumors (m-SDTs). METHODS: We retrospectively reviewed the clinical outcome of 22 consecutive cases of m-SDTs and analyzed the prognostic factors associated with worse outcome. RESULTS: Nineteen of the 22 cases were managed with surgery (86%), and gross total resection (GTR) was achieved in four cases (21%). The duration of overall survival (OS) ranged from 3 to 140 months, with a median survival time of 15.3 months. The 5 year OS rate was 55.6%. In multivariate analysis, histological subtype (high-grade malignant peripheral nerve sheath tumor) (hazard ratio [HR] 14.9, p = 0.0191), GTR (HR 0.07, p = 0.0343), and presence of local recurrences (HR 11.2, p = 0.0479) were significant and independent predictors of OS. CONCLUSIONS: On the basis of clinical data, we propose that GTR and prevention of local recurrence may improve the clinical outcome of m-SDTs.

Radiological Examination of Postoperative Cervical Alignment and Stability in Patients with Dialysis-Associated Spondylosis Excluding Destructive Spondyloarthropathy: Comparison with Patients with Cervical Spondylotic Myelopathy.

INTRODUCTION: Several reports have demonstrated the surgical treatment strategy for patients with dialysis-associated spondylosis in the cervical spine (CDAS) with destructive spondyloarthropathy (DSA). However, studies focusing on the clinical outcome of patients with CDAS without DSA remain scarce. We aimed to review the treatment strategy of patients with CDAS but without DSA. METHODS: The clinical data and surgical records of consecutive patients with CDAS without DSA (n = 9; D-group) and cervical spondylotic myelopathy (CSM) (n = 30; C-group) who underwent modified double-door laminoplasty(DDL) were reviewed retrospectively. We investigated four radiologic factors in the pre-and postoperative periods that have been reported to be the risk factors for worsening of clinical symptoms in various studies and examined statistical comparison between the D and C groups. RESULTS: In the D group, the pre- versus postoperative C2-C7 sagittal angles were not significantly different, and only two patients (22%) had kyphosis postoperatively. There was a significant difference in the pre- and postoperative C2-C7 angles in the two groups (P = 0.031). Regarding the change in segmental alignment, the local open angle increased at the C4/C5 level in the D group. Also there was a significant difference in the local angles between the two groups at C4/5 and C5/6 (P = 0.00038, and 0.037), suggesting that postoperative segmental mobility at C4/5 and C5/6 was higher in the D group than in the C group. CONCLUSIONS: In the present study, DDL in patients with CDAS without DSA did not adversely affect the postoperative alignment and stability compared with CSM patients with CSM. However, patients in the D group may have a chance to develop DSA change at the C4/5 level in the future, and careful long-term follow-up is warranted.

Macrophage Infiltration Is a Causative Factor for Ligamentum Flavum Hypertrophy through the Activation of Collagen Production in Fibroblasts.

Ligamentum flavum (LF) hypertrophy causes lumbar spinal canal stenosis, leading to leg pain and disability in activities of daily living in elderly individuals. Although previous studies have been performed on LF hypertrophy, its pathomechanisms have not been fully elucidated. In this study, we demonstrated that infiltrating macrophages were a causative factor for LF hypertrophy. Induction of macrophages into the mouse LF by applying a microinjury resulted in LF hypertrophy along with collagen accumulation and fibroblasts proliferation at the injured site, which were very similar to the characteristics observed in the severely hypertrophied LF of human. However, we found that macrophage depletion by injecting clodronate-containing liposomes counteracted LF hypertrophy even with microinjury. For identification of fibroblasts in the LF, we used collagen type I α2 linked to green fluorescent protein transgenic mice and selectively isolated green fluorescent protein-positive fibroblasts from the microinjured LF using laser microdissection. A quantitative RT-PCR on laser microdissection samples revealed that the gene expression of collagen markedly increased in the fibroblasts at the injured site with infiltrating macrophages compared with the uninjured location. These results suggested that macrophage infiltration was crucial for LF hypertrophy by stimulating collagen production in fibroblasts, providing better understanding of the pathophysiology of LF hypertrophy.

Incidental Cerebral Acute Subdural Hematoma After Transforaminal Lumbar Interbody Fusion: A Case Report.

We present a 68-year-old woman who developed acute cerebral subdural hematoma (SDH) early after transforaminal lumbar interbody fusion. Four hours postoperatively, the patient complained of headache and nausea. Enhanced cranial computed tomography showed cerebral SDH. Despite no obvious intraoperative dural damage, we suggest that cerebrospinal fluid leakage by incidental dural tear likely caused the SDH. To our knowledge, this is the first report of detected cerebral SDH immediately after spinal surgery in spite of no neurological deficits.

A case of superficial siderosis ameliorated after closure of dural deficit detected by MRI-CISS (constructive interference in steady state) imaging.

A 64-year-old male developed headache, dizziness, and difficulty hearing, two years after an operation for chronic subdural hematoma due to head injury. These symptoms gradually worsened over the following 15 years. As he showed bloody cerebrospinal fluid (CSF) and marginal hypointensity on the surface of the brain and spinal cord on T2/T2*-weighted MRI, he was diagnosed with superficial siderosis (SS), although the source of the bleeding was unclear and anti-hemorrhagic drugs were ineffective. When he was admitted to our hospital, neurological examination disclosed horizontal gaze-evoked nystagmus, severe bilateral hearing loss, scanning speech, and limb and truncal ataxia. CISS (constructive interference in steady state) MRI detected a dural defect at the Th2-3 level on the anterior side of the spinal canal. On operation, a 2 mm × 6 mm size dural defect with blood clots was found at the Th2-3 level. After closure of the dural defect, bloody CSF became transparent, and his persistent headache, dizziness, and hearing impairment improved. Brain and whole spine MRI, especially CISS imaging, should be considered for detecting the source of bleeding in intractable cases of SS.

Experimental Mouse Model of Lumbar Ligamentum Flavum Hypertrophy.

Lumbar spinal canal stenosis (LSCS) is one of the most common spinal disorders in elderly people, with the number of LSCS patients increasing due to the aging of the population. The ligamentum flavum (LF) is a spinal ligament located in the interior of the vertebral canal, and hypertrophy of the LF, which causes the direct compression of the nerve roots and/or cauda equine, is a major cause of LSCS. Although there have been previous studies on LF hypertrophy, its pathomechanism remains unclear. The purpose of this study is to establish a relevant mouse model of LF hypertrophy and to examine disease-related factors. First, we focused on mechanical stress and developed a loading device for applying consecutive mechanical flexion-extension stress to the mouse LF. After 12 weeks of mechanical stress loading, we found that the LF thickness in the stress group was significantly increased in comparison to the control group. In addition, there were significant increases in the area of collagen fibers, the number of LF cells, and the gene expression of several fibrosis-related factors. However, in this mecnanical stress model, there was no macrophage infiltration, angiogenesis, or increase in the expression of transforming growth factor-ß1 (TGF-ß1), which are characteristic features of LF hypertrophy in LSCS patients. We therefore examined the influence of infiltrating macrophages on LF hypertrophy. After inducing macrophage infiltration by micro-injury to the mouse LF, we found excessive collagen synthesis in the injured site with the increased TGF-ß1 expression at 2 weeks after injury, and further confirmed LF hypertrophy at 6 weeks after injury. Our findings demonstrate that mechanical stress is a causative factor for LF hypertrophy and strongly suggest the importance of macrophage infiltration in the progression of LF hypertrophy via the stimulation of collagen production.

Bone and soft tissue tumors presenting as sciatic notch dumbbell masses: A critical differential diagnosis of sciatica.

AIM: To study the clinical findings and characteristic features in sciatic notch dumbbell tumors (SNDTs). METHODS: We retrospectively reviewed the clinical outcomes and characteristic features of consecutive cases of SNDTs (n = 8). RESULTS: Buttock masses occurred in three patients with SNDT (37.5%). Severe buttock tenderness and pain at rest were observed in seven patients with SNDTs (87.5%). Remarkably, none of the patients with SNDTs experienced back pain. Mean tumor size was 8.4 ± 2.0 cm (range, 3.9 to 10.6 cm) and part of the tumor mass was detected in 2 patients in the sagittal view of lumbar magnetic resonance imaging (MRI). CONCLUSION: The clinical information regarding to SNDTs is scarce. The authors consider that above mentioned characteristic findings may facilitate the suspicion of pelvic pathology and a search for SNDT by MRI or computed tomography should be considered in patients presenting with sciatica without evidence of spinal diseases.