Spinal Post-traumatic Deformity: An International Expert Survey Among AO Spine Knowledge Forum Members.

STUDY DESIGN: Survey among spine experts. OBJECTIVE: To investigate the different views and opinions of clinically relevant spinal post-traumatic deformity (SPTD). SUMMARY OF BACKGROUND DATA: There is no clear definition of clinically relevant SPTD. This leads to a wide variation in characteristics used for diagnosis and treatment indications of SPTD. To understand the current concepts of SPTD a survey was conducted among spine trauma surgeons. METHODS: Members of the AO Spine Knowledge Forum Trauma participated in an online survey. The survey was divided in 4 domains: Demographics, criteria to define SPTD, risk factors, and management. The data were collected anonymously and analyzed using descriptive statistics, absolute, and relative frequencies. Consensus on dichotomous outcomes was set to 80% of agreement. RESULTS: Fifteen members with extensive experience in treatment of spinal trauma participated, representing the 5 AO Spine Regions. Back pain was the only criterion for definition of SPTD with complete agreement. Consensus (≥80%) was reached for kyphotic angulation outside normative ranges and impaired function. Eighty-seven percent and 100% agreed that a full-spine conventional radiograph was necessary in diagnosing and treating SPTD, respectively. The "missed B-type injury" was rated at most important by all but 1 participant. There was no agreement on other risk factors leading to clinically relevant SPTD. Concerning the management, all participants agreed that an asymptomatic patient should not undergo surgical treatment and that neurological deficit is an absolute surgical indication. For most of the participants the preferred surgical treatment of acute injury in all spine regions but the subaxial region is posterior fixation. CONCLUSION: Some consensus exists among leading experts in the field of spine trauma care concerning the definition, diagnosis, risk factors, and management of SPTD. This study acts as the foundation for a Delphi study among the global spine community.

Correlation of Early Outcomes and Intradiscal Interleukin-6 Expression in Lumbar Fusion Patients.

OBJECTIVE: To determine if there is correlation between intradiscal levels of interleukin-6 (IL-6) and early outcome measures in patients undergoing lumbar fusion for painful disc degeneration. METHODS: Intervertebral disc tissue was separated into annulus fibrosus/nucleus pulposus and cultured separately in vitro in serum-free medium (Opti-MEM). Conditioned media was collected after 48 hours. The concentration of IL-6 was quantified using enzyme-linked immunosorbent assay. Pearson correlation coefficients quantified relationships between IL-6 levels and pre- and postoperative visual analogue scale (VAS) back pain and Oswestry Disability Index (ODI), as well as change in VAS/ODI. RESULTS: Sixteen discs were harvested from 9 patients undergoing anterior lumbar interbody fusion (mean age, 47.4 years; range, 21-70 years). Mean preoperative and 6-month postoperative VAS were 8.1 and 3.7, respectively. Mean preoperative and postoperative ODI were 56.2 and 25.6, respectively. There were significant positive correlations between IL-6 expression and postoperative VAS (ρ = 0.38, p = 0.048) and ODI (ρ = 0.44, p = 0.02). No significant correlations were found between intradiscal IL-6 expression and preoperative VAS (ρ = -0.12, p = 0.54). Trends were seen associating IL-6 expression and change in VAS/ODI (ρ = -0.35 p = 0.067; ρ = -0.34, p = 0.08, respectively). A trend associated IL-6 and preoperative ODI (ρ = 0.36, p = 0.063). CONCLUSION: The direct association between IL-6 expression and VAS/ODI suggests patients with elevated intradiscal cytokine expression may have worse early outcomes than those with lower expression of IL-6 after surgery for symptomatic disc degeneration.

Management of Herniated Lumbar Disk Disease and Cauda Equina Syndrome in Pregnancy.

Lower back pain is a commonly reported symptom during pregnancy. However, herniated lumbar disk disease is an uncommon cause for such pain. Cauda equina syndrome (CES) during pregnancy is a rare clinical scenario. This review highlights the epidemiology, diagnostic and treatment strategies, and challenges encountered when managing herniated lumbar disk disease and CES in pregnancy. Magnetic resonance imaging is the diagnostic modality of choice. Nonoperative treatment strategies are successful in the vast majority of cases in patients with a herniated disk in the absence of CES. CES and progressive neurological deficits remain absolute indications for surgical intervention regardless of gestational age. For such patients or those with debilitating symptoms refractory to nonoperative treatment strategies, surgery has been demonstrated to be safe in the pregnant patient population. However, surgery should be performed with obstetric and midwifery support should complications occur to the fetus.

The local cytokine and growth factor response to recombinant human bone morphogenetic protein-2 (rhBMP-2) after spinal fusion.

BACKGROUND CONTEXT: The systemic response regarding cytokine expression after the application of recombinant human bone morphogenetic protein-2 (rhBMP-2) in a rat spinal fusion model has recently been defined, but the local response has not been defined. Defining the local cytokine and growth factor response at the fusion site will help explain the roles of these molecules in the fusion process, as well as that of rhBMP-2. Our hypothesis is that the application of rhBMP-2 to the fusion site will alter the local levels of cytokines and growth factors throughout the fusion process, in a manner that is different from the systemic response, given the tissue-specific effects of rhBMP-2. PURPOSE: The purpose of this study was to evaluate the local cytokine and growth factor response after the application of rhBMP-2 in a rat spinal fusion model. STUDY DESIGN/SETTING: This was a basic science animal model study. METHODS: This study was partially funded by a physician-sponsored grant from Medtronic. A total of 135 Wistar rats (age 8 weeks, weighing approximately 300-400 g) underwent L4-L5 posterolateral intertransverse fusion with demineralized bone graft (approximately 0.4-cm3 rat demineralized bone matrix [DBM] per side). In the first group, 10 µg of rhBMP-2 on an allograft collagen sponge (ACS) was added to the fusion site with approximately 0.4-cm3 rat DBM per side. In the second group, 100 µg of rhBMP-2 on an ACS was added to the fusion site with approximately 0.4-cm3 rat DBM per side, and the third experiment was the control group, which consisted of only an ACS plus 0.4-cm3 DBM per side. There were nine groups of five animals each per experiment. Each group was sacrificed at time points up to 4 weeks (1, 6, 24, and 48 hours, and 4, 7, 14, 21, and 28 days after surgery). At sacrifice, the DBM, transverse processes, and any new bone formed were harvested, immediately frozen in liquid nitrogen, and prepared for protein extraction. ELISA was performed to compare the levels of various cytokines (interleukin [IL]-1ß, tumor necrosis factor alpha, IL-6, IL-1RA [IL-1 receptor antagonist], IL-4, and IL-10) and growth factors (vascular endothelial growth factor [VEGF], endothelia growth factor [EGF], insulin-like growth factor-1 [IGF-1], platelet derived growth factor [PDGF], transforming growth factor beta [TGF-ß]) that are known to be involved in the fusion-fracture healing process. Fusion was evaluated on the rats sacrificed at 28 days by manual palpation and microcomputed tomography (microCT) by two independent observers. RESULTS: The expression of cytokines and growth factors varied throughout the fusion process at each time point. In the groups treated with rh-BMP-2, IL-6 and IL-1RA had higher expression in the early time points (1 and 6 hours). Tumor necrosis factor alpha demonstrated significantly lower expression in the groups treated with rhBMP-2 at Days 1, 2, and 4. At the early time points (1 and 6 hours), in the groups treated with rhBMP-2, all of the growth factors IGF-1, VEGF, platelet derived growth factor AB (PDGF-AB), TGF-ß had equal or lower expression compared with controls. At 24 hours, there was a peak in IGF-1, VEGF, and PDGF-AB. These growth factors then declined, with IGF-1 and PDGF-AB having a second peak at Day 7. At 4 weeks, all of the rhBMP-2-treated animals fused based on manual palpation and microCT. The control group had four of five rats fused based on manual palpation and two of five rats based on microCT. CONCLUSIONS: There is significant variability in the expression of cytokines throughout the fusion process after treatment with rhBMP-2. The inflammatory response appears to peak early (1 and 6 hours), followed by a significant decrease with rhBMP-2 treatment. However, the growth factor expression appears to be suppressed early (1 and 6 hours), followed by a peak at 24 hours, and a second peak at Day 7.

Sylvatic Plague Vaccine Partially Protects Prairie Dogs (Cynomys spp.) in Field Trials.

Sylvatic plague, caused by Yersinia pestis, frequently afflicts prairie dogs (Cynomys spp.), causing population declines and local extirpations. We tested the effectiveness of bait-delivered sylvatic plague vaccine (SPV) in prairie dog colonies on 29 paired placebo and treatment plots (1-59 ha in size; average 16.9 ha) in 7 western states from 2013 to 2015. We compared relative abundance (using catch per unit effort (CPUE) as an index) and apparent survival of prairie dogs on 26 of the 29 paired plots, 12 with confirmed or suspected plague (Y. pestis positive carcasses or fleas). Even though plague mortality occurred in prairie dogs on vaccine plots, SPV treatment had an overall positive effect on CPUE in all three years, regardless of plague status. Odds of capturing a unique animal were 1.10 (95% confidence interval [C.I.] 1.02-1.19) times higher per trap day on vaccine-treated plots than placebo plots in 2013, 1.47 (95% C.I. 1.41-1.52) times higher in 2014 and 1.19 (95% C.I. 1.13-1.25) times higher in 2015. On pairs where plague occurred, odds of apparent survival were 1.76 (95% Bayesian credible interval [B.C.I.] 1.28-2.43) times higher on vaccine plots than placebo plots for adults and 2.41 (95% B.C.I. 1.72-3.38) times higher for juveniles. Our results provide evidence that consumption of vaccine-laden baits can protect prairie dogs against plague; however, further evaluation and refinement are needed to optimize SPV use as a management tool.