Julio Urrutia

Early Histologic Changes Following Polymethylmethacrylate Injection (Vertebroplasty) in Rabbit Lumbar Vertebrae

Study Design. An ex vivo histologic study in rabbits. Objective. To evaluate the early histologic effects of polymethylmethacrylate (PMMA) injection on bone and intraosseous neural tissue following vertebroplasty in rabbit lumbar vertebrae. Summary of Background Data. Vertebroplasty with PMMA is performed to treat painful osteoporotic vertebral fractures. Early pain relief has been consistently documented, but its mechanism has not been elucidated. Among the mechanisms of pain relief may be the immediate stabilizing effects of the cement, and the exothermic reaction during curing, which may lead to intraosseous neural ablation. It has been well established that PMMA can induce thermal osteonecrosis after arthroplasty, but the potential for osteonecrosis after vertebroplasty has not been established. Previous studies have suggested that temperature elevations during cement curing may induce thermal bone necrosis. However, this cause-and-effect relationship has not yet been histologically studied in an animal model. Methods. Vertebroplasty with PMMA was performed at 2 levels in 12 New Zealand rabbits (24 levels); trochar insertion without PMMA injection was performed at 3 levels each of 2 control animals (6 levels). Sacrifice was performed 24 hours after the procedure. Histologic examination was performed to evaluate the presence of bone or intraosseous neural tissue necrosis. Results. Half of the levels with PMMA showed evidence of necrosis at the bone-cement interface. Almost all (11 of 12) showed only focal necrosis, with only 1 specimen showing necrosis along the entire periphery of the PMMA. The other 12 specimens and all control levels displayed no bone necrosis. There was no evidence of intraosseous neural tissue necrosis in control or PMMA-injected specimens. Conclusion. Injection of PMMA in rabbit lumbar vertebral bodies produces early, focal bone necrosis in only half of cases, suggesting that competency of the cement-bone interface is reasonable in most cases. No evidence of intraosseous neural tissue damage was found.

Long-term results of surgical treatment of dysphagia secondary to cervical diffuse idiopathic skeletal hyperostosis

BACKGROUND CONTEXT Large, prominent osteophytes along the anterior aspect of the cervical spine have been reported as a cause of dysphagia. Improvement of swallowing after surgical resection has been reported in a few case reports with short-term follow-up. The current report describes outcomes of a series of five patients with surgical treatment for this rare disorder, with a long-term follow-up. PURPOSE To study the clinical and radiographic outcomes of a case series of patients surgically treated for dysphagia secondary to cervical diffuse idiopathic skeletal hyperostosis (DISH). STUDY DESIGN Retrospective review of a case series. PATIENT SAMPLE Five cases from a University Hospital. OUTCOME MEASURES Clinical and imagenological follow-up. METHODS The records of five patients with dysphagia who had undergone anterior surgical resection of prominent osteophytes secondary to DISH were reviewed. Extrinsic esophageal compression secondary to anterior cervical osteophytes was radiographically confirmed via preoperative barium esophagogram swallowing study. All patients underwent anterior cervical osteophytes resection without fusion. Postoperatively, patients were followed-up clinically and radiographically with routine lateral cervical radiographs. RESULTS Preoperative esophagogram showed that the esophageal obstruction was present at one level in three cases and two levels in two cases. The C3-C4 level was involved in three cases, C4-C5 in three cases, and C5-C6 in one case. There were no postoperative complications, including recurrent laryngeal nerve palsy, wound infection, or hematomas. All patients had resolution of dyphagia soon after surgery (within 2 weeks). Postoperative radiographs demonstrated complete removal of osteophytes. At final follow-up, ranging from 1 to 9 years (average 59.8 months, median 53 months), no patients reported recurrence of dysphagia. Final radiographic examination demonstrated minimal regrowth of the osteophytes. CONCLUSIONS Although rarely indicated, surgical resection of anterior cervical osteophytes from DISH causing dyphagia produces good clinical and radiographical outcomes. After thorough evaluation to rule out other intrinsic or extrinsic causes of swallowing difficulty, surgical treatment of this uncommon condition might be considered.

The Spine Instability Neoplastic Score: an independent reliability and reproducibility analysis.

BACKGROUND Metastatic vertebral instability has not yet been clearly defined in the literature; there still exists a paucity of reliable criteria to assess the risk of vertebral collapse. PURPOSE We performed an independent interobserver and intraobserver agreement evaluation of the Spine Instability Neoplastic Score (SINS) and correlated the score with selected clinical cases and the treatment they received. STUDY DESIGN Independent reliability study for the newly created SINS. PATIENT SAMPLE Thirty patients who underwent either radiotherapy alone or surgery followed by radiotherapy were randomly selected from the orthopedic surgery and radiotherapy departments databases. OUTCOME MEASURES Patients were rated and classified for spinal stability using SINS. Intraclass correlation coefficient (ICC) and Fleisss kappa measures were occupied for reliability analysis. METHODS Patients who underwent either radiotherapy alone or surgery followed by radiotherapy were randomly selected and classified for spinal stability using the SINS by orthopedic surgeons and nonorthopedic oncology specialists. ICC and Fleisss kappa were calculated for inter- and intraobserver agreement. A comparative analysis of SINS and the actual management was also conducted. RESULTS Interobserver ICC reliability for the SINS was 0.79; κ values for location, pain, bone quality, alignment, vertebral body collapse, and posterolateral involvement were 0.81, 0.58, 0.21, 0.45, 0.42, and 0.29 respectively. Intraobserver ICC for the SINS scores was 0.96; ICC values for the same components were 0.98, 0.98, 0.87, 0.88, 0.92, and 0.86, respectively. Potentially unstable lesions (SINS score≥7) were operated on in 62.5%. CONCLUSIONS SINS seem to be a reproducible tool that could be used equally by multiple specialists to estimate metastatic vertebral stability; however, prospective clinical validation is still pending.

An independent interobserver reliability and intraobserver reproducibility evaluation of the new AOSpine Thoracolumbar Spine Injury Classification System.

Study Design. Agreement study. Objective. To perform an independent interobserver and intraobserver agreement evaluation of the new AOSpine Thoracolumbar Spine Injury Classification System. Summary of Background Data. The new AOSpine Thoracolumbar Spine Injury Classification System was recently published. It showed substantial reliability and reproducibility among the surgeons who developed it; however, an independent evaluation has not been performed. Methods. Anteroposterior and lateral radiographs, and computed tomographic scans of 70 patients with acute traumatic thoracolumbar injuries were selected and classified using the morphological grading of the new AOSpine Thoracolumbar Spine Injury Classification System by 6 evaluators (3 spine surgeons and 3 orthopedic surgery residents). After a 6-week interval, the 70 cases were presented in a random sequence to the same evaluators for repeat evaluation. The Kappa coefficient (&kgr;) was used to determine the interobserver and intraobserver agreement. Results. The interobserver reliability was substantial when considering the fracture type (A, B, or C), with a &kgr;= 0.62 (0.57–0.66). The interobserver agreement when considering the subtypes was moderate; &kgr;= 0.55 (0.52–0.57). The intraobserver reproducibility was also substantial, with 85.95% full intraobserver reproducibility considering the fracture type, with &kgr;= 0.77 (0.72–0.83), and was also substantial when considering subtypes with 75.71% full agreement and &kgr;= 0.71 (0.67–0.76). No significant differences were observed between spine surgeons and orthopedic residents in the overall interobserver reliability and intraobserver reproducibility, or in the inter- and intraobserver agreement of specific A, B, or C types of injuries. Conclusion. This classification allows adequate agreement among different observers and by the same observer on separate occasions. Future prospective studies should evaluate whether this classification improves clinical decision making. Level of Evidence: 2

DNA methylation profile in diffuse type gastric cancer: evidence for hypermethylation of the BRCA1 promoter region in early-onset gastric carcinogenesis

Diffuse type gastric carcinoma is the most aggressive type of gastric cancer. This type of tumor is not preceded by precancerous changes and is associated with early-onset and hereditary syndromes. To test the hypothesis that DNA methylation profile would be useful for molecular classification of the diffuse type gastric carcinoma, DNA methylation patterns of the CpG Island of 17 genes were studied in 104 cases and 47 normal adjacent gastric mucosa by Methylation-specific PCR, Immunohistochemistry and Hierarchical clustering analysis. The most frequent methylated genes were FHIT, E-cadherin, BRCA1 and APC (>50%), followed by p14, p16, p15, p73, MGMT and SEMA3B (20-49%). Hierarchical clustering analysis reveals four groups with different clinical features. The first was characterized by hypermethylation of BRCA1 and younger age (<45 years old), and the second by hypermethylation of p14 and p16 genes, male predominance and Epstein-Barr virus infection. The third group was characterized by hypermethylation of FHIT and antrum located tumors and the fourth was not associated with any clinical variables. In normal adjacent mucosa only the p73 gene was significantly less methylated in comparison to tumor mucosa. DNA methylation identified subgroups of diffuse type gastric cancer. Hypermethylation of BRCA1 associated with young age suggests a role in early-onset gastric carcinoma.

Lumbar scoliosis in postmenopausal women: prevalence and relationship with bone density, age, and body mass index.

Study Design. Cross-sectional study. Objective. The aim of this study was to investigate the prevalence of lumbar scoliosis in postmenopausal women aged 50 years and older, and to determine the association of adult lumbar scoliosis with age, osteoporosis, and body mass index (BMI). Summary of Background Data. Adult scoliosis prevalence has not been clearly determined. In addition, limited data are available on the correlation of adult scoliosis with age, bone mineral density, and BMI. Methods. We studied 380 postmenopausal women aged 50 years and older, who were evaluated with dual-energy radiograph absorptiometry (DXA) scan images. The lumbar curvature magnitude in the coronal plane was measured in DXA images with Cobbs method. Scoliosis was defined by the presence of a curvature 10° or larger. Age and T-score in the lumbar spine and in both femoral necks were recorded, and BMI was calculated. Correlation analysis among the studied variables was performed, as well as a linear regression analysis to determine the effect of femoral neck T-score, spine T-score, age, and BMI as independent predictors of the Cobb angle in the lumbar spine. Results. The prevalence of lumbar scoliosis was 12.9% (49 cases); 43 cases (11.3%) had lumbar curves 10° or more but less than 20°, and six cases (1.6%) had lumbar curves more than 20°. Age and BMI were independent predictors of the Cobb angle; the femoral neck T-score and the lumbar T-score were not independent predictors of the Cobb angle. Conclusion. We found a 12.9% prevalence of lumbar scoliosis in postmenopausal women aged 50 years and older, most of them with mild curves. Age and BMI are independent predictors of lumbar scoliosis. Bone mineral density (BMD) is not an independent predictor of the magnitude of the curve.

Clinical and imaging findings in patients with aggressive spinal hemangioma requiring surgical treatment

Vertebral hemangiomas (VHs) are frequently asymptomatic lesions found incidentally during investigations for other spinal problems. Symptomatic VHs are less common, and there are few reports of compressive VHs in the literature. VHs with aggressive behavior present with low signal intensity on T1-weighted and high signal intensity on T2-weighted MRI. We present a case series of four patients with compressive VH, all of whom were neurologically compromised. Each of the four patients underwent preoperative arterial embolization followed by surgical treatment of their VHs. All patients recovered normal motor function after surgery. At follow-up (average 53 months), one patient had a recurrent tumor requiring reoperation and radiotherapy. Although it is rare, aggressive VH can be a devastating condition. Total surgical resection or subtotal resection with radiotherapy may be warranted.

Cultured autologous bone marrow stem cells inhibit bony fusion in a rabbit model of posterolateral lumbar fusion with autologous bone graft

Mesenchymal stem cells (MSCs) have been isolated from various tissues and expanded in culture. MSCs add osteogenic potential to ceramic scaffolds when used together. A spinal fusion rabbit model was used to evaluate whether a pellet of cultured, autologous bone marrow MSCs (BMSCs) with osteogenic differentiation could increase the fusion rate when co-grafted with an autologous bone graft compared to autograft alone. Thirty rabbits were randomly assigned to two groups. Group 1 received bone autograft alone and Group 2 received bone autograft plus a pellet of cultured and differentiated BMSCs. Group 2 rabbits had a bone marrow puncture, after which the BMSC were cultured and osteoblastic differentiation was induced. BMSC cultures were obtained from 12 of 15 rabbits. The 27 rabbits underwent a bilateral, L4-L5 intertransverse fusion with an autograft and in Group 2 rabbits a pellet of differentiated BMSCs was added to the autograft. In Group 1, the fusion rate was 53% (8 of 15 rabbits) and in Group 2 the fusion rate was 0% (p<0.05). Adding differentiated BMSCs in a pellet without a scaffold not only failed to increase fusion rate, but completely inhibited bony growth.

Factors associated with variability in length of sick leave because of acute low back pain in Chile

BACKGROUND CONTEXT Acute low back pain (LBP) is a frequent cause of physician visits and sick leave. Patients with longer sick leave account for most costs associated with LBP. Most research on risk factors for prolonged sick leave because of LBP has been done in Anglo-Saxon or Northern European populations with occupational LBP. Few studies have been conducted in less affluent Latin countries. PURPOSE To investigate the prevalence of acute LBP as a cause of sick leave and the variables associated with longer work absence (WA) because of acute LBP in Chile. STUDY DESIGN A retrospective study of nonoccupational sick leave certificates issued in a 1-year period by the Chilean Public Health System. PATIENT SAMPLE Ten thousand cases with nonoccupational sick leave certificates issued with the diagnosis of acute LBP. OUTCOME MEASURES Prevalence of acute LBP as a cause of sick leave, days of WA, and subsidy payment. METHODS A review of sick leave certificates from patients with different diagnoses was done to determine the prevalence of acute LBP as a cause of sick leave. We investigated whether age, gender, history of at least one episode of sick leave in the previous year because of acute LBP or because of other diagnoses, stipendiary subsidy paid (converted to US

The effect of ketoprophen on lumbar spinal fusion healing in a rabbit model. Laboratory investigation.

), work activity, occupation, and the specialty of the attending physician influenced the length of sick leave. RESULTS Acute LBP represented 5.4% of cases causing sick leave. Patients with acute LBP who had significantly longer sick leave than the rest of the population were patients with an episode of WA because of LBP in the previous year (14% longer sick leave than patients without that history), manual workers (35% longer than nonmanual workers), and patients seen by orthopedic surgeons (43% longer than patients seen by other medical specialists). Nonpregnant women and men had similar durations of sick leave because of acute LBP. CONCLUSIONS Physicians who treat patients with LBP should be aware of these variables associated with longer sick leave because of acute LBP, which represents a significant burden to any society and is an important epidemiologic problem.