High Risk of Symptomatic Venous Thromboembolism After Surgery for Spine Metastatic Bone Lesions: A Retrospective Study.

BACKGROUND: Cancer and spinal surgery are both considered risk factors for venous thromboembolism (VTE). However, the risk of symptomatic VTE for patients undergoing surgery for spine metastases remains undefined. QUESTIONS/PURPOSES: The purposes of this study were to: (1) identify the proportion of patients who develop symptomatic VTE within 90-days of surgical treatment for spine metastases; (2) identify the factors associated with the development of symptomatic VTE among patients receiving surgery for spine metastases; (3) assess the association between the development of postoperative symptomatic VTE and 1-year survival among patients who underwent surgery for spine metastases; and (4) assess if chemoprophylaxis increases the risk of wound complications among patients who underwent surgery for spine metastases. METHODS: Between 2002 and 2014, 637 patients at two hospitals underwent spine surgery for metastases. We considered eligible for analysis adult patients whose procedures were to treat cervical, thoracic, or lumbar metastases (including lymphoma and multiple myeloma). At followup after 90 days and 1 year, respectively, 21 of 637 patients (3%) and 41 of 637 patients (6%) were lost to followup. In general, we used 40 mg of enoxaparin or 5000 IUs subcutaneous heparin every 12 hours. Patients on preoperative chemoprophylaxis continued their initial medication postoperatively. All chemoprophylaxis was started 48 hours after surgery and continued day to day but was discontinued if a bleeding complication developed. Low-molecular-weight heparin (including enoxaparin and dalteparin, in general dosages of respectively 40 mg and 5000 IUs daily) was the most commonly used chemoprophylaxis in 308 patients (48%). Subcutaneous heparin was injected into 127 patients (20%); aspirin was used for 92 patients (14%); and warfarin was administered in 21 patients (3.3%). No form of chemoprophylaxis was prescribed for 89 patients (14%). The primary outcome variable, VTE, was defined as any symptomatic pulmonary embolism (PE) or symptomatic deep venous thromboembolism (DVT) within 90 days of surgery as determined by chart review. The secondary outcome was defined as any documented wound complication within 90 days of surgery that might be attributable to chemoprophylaxis. Statistical analysis was performed using multivariable logistic and Cox regression and Kaplan-Meier. RESULTS: Overall, 72 of 637 patients (11%) had symptomatic VTE; 38 (6%) developed a PE-eight (1.3%) of which were fatal-and 40 (6%) a DVT. After controlling for relevant confounding variables such as age, the modified Charlson Comorbidity Index, visceral metastases, and chemoprophylaxis, longer duration of surgery was independently associated with an increased risk of symptomatic VTE (odds ratio 1.15 for each additional hour of surgery; 95% confidence interval [CI], 1.04-1.28; p = 0.009). After controlling for relevant confounding variables such as age, the modified Charlson Comorbidity Index, visceral metastases, and primary tumor type, patients with symptomatic VTE had a worse 1-year survival rate (VTE, 38%; 95% CI, 27-49 versus nonVTE, 47%; 95% CI, 42-51; p = 0.044). After controlling for relevant confounding variables, no association was found between wound complications and the use of chemoprophylaxis (odds ratio, 1.34; 95% CI, 0.62-2.90; p = 0.459). The overall proportion of patients who developed a wound complication was 10% (66 of 637), including 1.1% (seven of 637) spinal epidural hematomas. CONCLUSIONS: The risk of both symptomatic PE and fatal PE is high in this patient population, and those with symptomatic VTE were less likely to survive 1-year than those who did not, though this may reflect overall infirmity as much as anything else, because many of these patients did not die from VTE-related complications. Further study, such as randomized controlled trials with consistent postoperative VTE screening comparing different chemoprophylaxis regimens, are needed to identify better VTE prevention strategies. LEVEL OF EVIDENCE: Level III, therapeutic study.

Inflammatory cytokines induce a unique mineralizing phenotype in mesenchymal stem cells derived from human bone marrow.

Bone marrow contains mesenchymal stem cells (MSCs) that can differentiate along multiple mesenchymal lineages. In this capacity they are thought to be important in the intrinsic turnover and repair of connective tissues while also serving as a basis for tissue engineering and regenerative medicine. However, little is known of the biological responses of human MSCs to inflammatory conditions. When cultured with IL-1ß, marrow-derived MSCs from 8 of 10 human subjects deposited copious hydroxyapatite, in which authenticity was confirmed by Fourier transform infrared spectroscopy. Transmission electron microscopy revealed the production of fine needles of hydroxyapatite in conjunction with matrix vesicles. Alkaline phosphatase activity did not increase in response to inflammatory mediators, but PPi production fell, reflecting lower ectonucleotide pyrophosphatase activity in cells and matrix vesicles. Because PPi is the major physiological inhibitor of mineralization, its decline generated permissive conditions for hydroxyapatite formation. This is in contrast to MSCs treated with dexamethasone, where PPi levels did not fall and mineralization was fuelled by a large and rapid increase in alkaline phosphatase activity. Bone sialoprotein was the only osteoblast marker strongly induced by IL-1ß; thus these cells do not become osteoblasts despite depositing abundant mineral. RT-PCR did not detect transcripts indicative of alternative mesenchymal lineages, including chondrocytes, myoblasts, adipocytes, ligament, tendon, or vascular smooth muscle cells. IL-1ß phosphorylated multiple MAPKs and activated nuclear factor-κB (NF-κB). Certain inhibitors of MAPK and PI3K, but not NF-κB, prevented mineralization. The findings are of importance to soft tissue mineralization, tissue engineering, and regenerative medicine.

Comparison of wideband steady-state free precession and T2-weighted fast spin echo in spine disorder assessment at 1.5 and 3 T.

Wideband steady-state free precession (WB-SSFP) is a modification of balanced steady-state free precession utilizing alternating repetition times to reduce susceptibility-induced balanced steady-state free precession limitations, allowing its use for high-resolution myelographic-contrast spinal imaging. Intertissue contrast and spatial resolution of complete-spine-coverage 3D WB-SSFP were compared with those of 2D T2-weighted fast spin echo, currently the standard for spine T2-imaging. Six normal subjects were imaged at 1.5 and 3 T. The signal-to-noise ratio efficiency (SNR per unit-time and unit-volume) of several tissues was measured, along with four intertissue contrast-to-noise ratios; nerve-ganglia:fat, intradural-nerves:cerebrospinal fluid, nerve-ganglia:muscle, and muscle:fat. Patients with degenerative and traumatic spine disorders were imaged at both MRI fields to demonstrate WB-SSFP clinical advantages and disadvantages. At 3 T, WB-SSFP provided spinal contrast-to-noise ratios 3.7-5.2 times that of fast spin echo. At 1.5 T, WB-SSFP contrast-to-noise ratio was 3-3.5 times that of fast spin echo, excluding a 1.7 ratio for intradural-nerves:cerebrospinal fluid. WB-SSFP signal-to-noise ratio efficiency was also higher. Three-dimensional WB-SSFP disadvantages relative to 2D fast spin echo are reduced edema hyperintensity, reduced muscle signal, and higher motion sensitivity. WB-SSFP's high resolution and contrast-to-noise ratio improved visualization of intradural nerve bundles, foraminal nerve roots, and extradural nerve bundles, improving detection of nerve compression in radiculopathy and spinal-stenosis. WB-SSFP's high resolution permitted reformatting into orthogonal planes, providing distinct advantages in gauging fine spine pathology.

Practice Variation Among Surgeons Treating Lumbar Spinal Stenosis in a Single Institution.

STUDY DESIGN: A retrospective study. OBJECTIVE: The aim of this study was to examine practice variation in the treatment of lumbar spinal stenosis and identify targets for reducing variation. SUMMARY OF BACKGROUND DATA: Lumbar spinal stenosis is a degenerative condition susceptible to practice variation. Reducing variation aims to improve quality, increase safety, and lower costs. Establishing differences in surgeons' practices from a single institution can help identify personalized variation. METHODS: We identified adult patients first diagnosed with lumbar spinal stenosis between 2003 and 2015 in three hospitals of the same institution with ICD-9 codes.We extracted number of office visits, imaging procedures, injections, electromyographies (EMGs), and surgery within the first year after diagnosis; physical therapy within the first 3 months after diagnosis. Multivariable logistic regression was used to identify factors associated with surgery. The coefficient of variation (CV) was calculated to compare the variation in practice. RESULTS: The 10,858 patients we included had an average of 2.5 visits (±1.9), 1.5 imaging procedures (±2.0), 0.03 EMGs (±0.22), and 0.16 injections (±0.53); 36% had at least one surgical procedure and 32% had physical therapy as part of their care. The CV was smallest for number of visits (19%) and largest for EMG (140%).Male sex [odds ratio (OR): 1.23, P < 0.001], seeing an additional surgeon (OR: 2.82, P < 0.001), and having an additional spine diagnosis (OR: 3.71, P < 0.001) were independently associated with surgery. Visiting an orthopedic clinic (OR: 0.46, P < 0.001) was independently associated with less surgical interventions than visiting a neurosurgical clinic. CONCLUSION: There is widespread variation in the entire spectrum of diagnosis and therapy for lumbar spinal stenosis among surgeons in the same institution. Male gender, seeing an additional surgeon, having an additional spine diagnosis, and visiting a neurosurgery clinic were independently associated with increased surgical intervention. The main target we identified for decreasing variability was the use of diagnostic EMG. LEVEL OF EVIDENCE: 3.

The posterior shearing tibial plateau fracture: treatment and results via a posterior approach.

OBJECTIVES: This study was designed to describe the fracture patterns and early results of treatment of posterior shearing tibial plateau fractures. DESIGN: Retrospective case series. SETTING: Tertiary care hospital. PATIENTS: Thirteen patients identified from prospective trauma database with posterior shearing tibial plateau fractures. INTERVENTION: Open reduction and internal fixation through a posterior approach to the knee. MAIN OUTCOME MEASUREMENTS: Functional outcome assessed by Musculoskeletal Functional Assessment score and Visual Analogue Scale pain scores. Clinical and radiographic outcome. RESULTS: A consistent fracture pattern was identified with a primary, inferiorly displaced posteromedial shear fracture with variable amounts of lateral condylar impaction. The average duration of clinical patient follow-up was 20 (range, 13-27) months. All fractures healed after index surgery. Two complications (1 wound dehiscence and 1 flexion contracture) were all managed nonoperatively. Three independent surgeons graded patients' articular reduction, with good interobserver reliability (intraclass correlation coefficient = 0.82). The average Musculoskeletal Function Assessment dysfunction score for the 9 patients who responded was 19.5/100, and average resting Visual Analogue Scale pain score was 1.8 cm/10 cm, indicating good function. The functional outcome score was significantly related to the quality of articular reduction (P < 0.017, R = 0.456). CONCLUSIONS: Posterior shearing tibial plateau fractures form a consistent pattern. They can be successfully managed using a posterior approach with direct reduction and buttress fixation of articular fragments. Quality of articular reduction is one factor that influences short-term functional outcome.

Thromboembolic disease in spinal surgery: a systematic review.

STUDY DESIGN: Systematic review of the literature and analysis of pooled data. OBJECTIVES: To better understand the incidence of thromboembolic disease in postoperative spinal patients, and to establish a starting point for defining appropriate postoperative prophylaxis protocols. SUMMARY OF BACKGROUND DATA: The risk of thromboembolic disease is well studied for some orthopedic procedures. However, the incidence of postoperative thromboembolic disease is less well-defined in patients who have had spinal surgery. METHODS: The MEDLINE database was queried using the search terms deep venous thrombosis or DVT, pulmonary embolus, thromboembolic disease, and spinal or spine surgery. Abstracts of all identified articles were reviewed. Detailed information from eligible articles was extracted. Data were compiled and analyzed by simple summation methods when possible to stratify rates of DVT and/or pulmonary embolus for a given prophylaxis protocol, screening method, and type of spinal surgery. RESULTS: Twenty-five articles were eligible for full review. DVT risk ranged from 0.3% to 31%, varying between patient populations and methods of surveillance. Pooling data from the 25 studies, the overall rate of DVT was 2.1%. DVT rate was influenced by prophylaxis method: no prophylaxis, 2.7%; compression stockings (CS), 2.7%; pneumatic sequential compression device (PSCD), 4.6%; PSCD and CS, 1.3%; chemical anticoagulants, 0.6%; and inferior vena cava filters with/without another method of prophylaxis, 22%. DVT rate was also influenced by the method of diagnosis, ranging from 1% to 12.3%. CONCLUSION: As risk of DVT after routine elective spinal surgery is fairly low, it seems reasonable to use CS with PSCD as a primary method of prophylaxis. There is insufficient evidence to support or refute the use of chemical anticoagulants in routine elective spinal surgery. In addition, there is insufficient evidence to suggest that screening patients undergoing elective spinal surgery with ultrasound or venogram is routinely warranted.