The EMS stress view: occult pelvic instability revealed by pre-hospital pelvic binder placement.

PURPOSE: To describe and evaluate the serendipitous pelvic binder stress radiographs of lateral compression type (LC) pelvic ring injuries. METHODS: This was a retrospective case series performed at a single, level I academic trauma center from 2016 to 2018. All patients presenting with a minimally displaced LC pelvic ring injury were reviewed (< 10 cm displacement on static pelvic radiographs). Patients with X-rays (XR) in a pelvic binder (EMS stress) and with the pelvic binder removed were included. Pelvic ring stability was determined by attending surgeon evaluation of EMS stress radiographs versus static XR of the pelvis. Patients were treated non-operatively and allowed to weight bear or taken to the operating room for exam under anesthesia (EUA) and potential operative fixation. Clinical success of treatment was determined by evaluation of further displacement at the completion of their most recent follow-up. RESULTS: Thirty-seven patients of the initial 398 reviewed met inclusion criteria. Fourteen of 37 patients (38%) were categorized as stable with no significant pelvis displacement seen on EMS stress and were treated non-operatively without further sequelae (4.6 months mean follow-up). The remaining 23/37 (62%) were treated operatively. Occult instability was identified on EMS stress in 14 (61%) of those 23 patients and the remainder were determined to be unstable based upon fracture pattern or EUA. All patients went on to successful treatment without significant pelvic deformity (7.8 months mean follow-up). CONCLUSION: The EMS stress XR is a valuable, opportunistic evaluation in LC pelvic ring injuries. This evaluation is a useful diagnostic adjunct to alert the provider that additional stress imaging may be indicated to evaluate for occult pelvic ring instability.

Quantification and visualization of anterior pelvis bone density to optimize screw fixation: A novel technique.

Plate fixation of anterior pelvic ring fractures is often a vital component when surgically treating unstable pelvis fractures. Certain plate and screw configurations can have premature implant loosening, potentially in part due to insufficient pullout strength in lower density bone. This study sought to define densities about the anterior pelvic ring using a novel computer-based technique. Thirty-three patients who received a computed tomography (CT) of the abdomen/pelvis for reasons other than pelvis fracture in a 1-month time period were included. Three statistically distinct density regions of the anterior pelvis were identified based on the three-dimensional (3D) density map. The densest regions included both the anterior and posterior aspects of the superior pubic ramus, along with the region of bone along the inferior cotyloid fossa. The intermediate density region included the caudal and medial pubic body. The least dense region included the anterior aspect of the inferior pubic ramus (IPR), the posterior pubic body, and the posterior/inferior IPR. This study presents specific quantification of anterior pelvis bone density based on a novel technique using opportunistic CT scans. Clinical Significance: Anterior surgical fixation of unstable pelvic ring injuries may benefit from targeting areas of higher density as described in this novel technique.

The effect of age and sex on pelvic bone density measured opportunistically in clinical CT scans.

Unstable pelvic ring fractures are severe and complex injuries, and surgical fixation is challenging and can be complicated by early failure due in part to difficulties with securely fixing screws in low-density bone. There is limited information in the literature about how the density distribution across the pelvic bones changes with age and sex. In this study, we used 60 sets of calibrated bone density measurements obtained opportunistically from clinical computed tomography scans of the pelvis. Three-dimensional models of the innominate bone were produced and the effects of age and sex on cortical bone density modeled. Overall trends and regions where these factors had a significant effect were identified, and the results visualized. Across the entire innominate bone, the mean loss of density was found to be 1.6 mg/cc per year, with several specific areas (pubic body, iliac fossa, posterior ilium, and anterior inferior iliac spine for example) showing significant rates of loss up to three times greater than the rest of the bone. Areas significantly affected by sex included the posterior pubic root, anterior aspect of the pubic body, and iliac crest. Despite overall trends of attenuation, there remains significant variability between individuals. This supports the need to further explore subject-specific planning tools for pelvic fracture repair. Statement of clinical significance: Bone density changes across the innominate bone due to age and sex tend to vary between individuals, although consistent effects were seen at specific regions. This information may help in surgical planning of unstable fracture repairs.

The Learning Curve of Suprapatellar Nailing: Adoption Over Time Can Decrease Operative Time and Radiation Exposure.

OBJECTIVE: To determine whether suprapatellar nailing (SPN) over time can decrease operative time and radiation exposure when compared with infrapatellar nailing (IPN) of tibial shaft fractures. DESIGN: Retrospective. SETTING: Single, Level 1 trauma center. PATIENTS: Extra-articular adult tibial shaft fractures treated with intramedullary nailing alone within a 7-year period. INTERVENTION: Patients were treated with SPN or IPN techniques based on the discretion of the operating surgeon. MAIN OUTCOME MEASUREMENTS: Operative time and radiation exposure. RESULTS: Three hundred forty-one fractures (SPN: 177, IPN: 164) were included in the analysis. No differences in patient body mass index, sex, or open fracture incidence existed between the 2 groups. A significant difference in average operative time (IPN 130 minutes vs. SPN 110 minutes, P < 0.01), fluoroscopy time (IPN 159 minutes vs. SPN 143 minutes, P = 0.02), and radiation dose (IPN 8.6 mGy vs. SPN 6.5 mGy, P < 0.01) existed between IPN and SPN. Early tibias treated with SPN had similar operative times (P = 0.11), fluoroscopy time (P = 0.94), and radiation dose (P = 0.34) compared with IPN. Later SPN patients had significantly lower operative time (P = 0.03), fluoroscopy time (P < 0.01), and radiation dose (P < 0.013) compared with earlier SPN. Regression analysis revealed with the increased use of SPN, operative time, fluoroscopy time, and radiation dose significantly decreased (P = 0.018, 0.046, 0.011). CONCLUSIONS: Tibia fractures treated with SPN have significantly decreased operative times and radiation exposure compared with those treated with IPN, after allowing time for the surgeon to gain sufficient experience with the technique. The surgeon should consider this when deciding to adopt this technique. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Titanium Elastic Nailing has Superior Value to Plate Fixation of Midshaft Femur Fractures in Children 5 to 11 Years.

BACKGROUND: American Academy of Orthopaedic Surgeons (AAOS) Clinical Practice Guidelines for pediatric femoral shaft fractures indicate titanium elastic nails (TENs) for children 5 to 11 years old. Growing evidence suggests these fractures may also be treated with open or submuscular plating. The purpose of this study was to compare estimated blood loss (EBL), operative time, fluoroscopy time, cost, and subjective and objective pain scores between TENs and plating techniques used in 5- to 11-year-old children with midshaft femur fractures based on length stability. We hypothesized that EBL, operative time, and fluoroscopy time would be greater and pain would be lower with plate fixation. METHODS: We retrospectively identified all pediatric midshaft femur fractures treated with TENs, submuscular plating, or open plating between 2004 and 2014. Demographic, injury, and surgical data were obtained for analysis. Cost data were obtained from Synthes Inc. Outcomes were determined using the TEN outcome scoring system. Variables were compared between the 3 fixation methods using paired t tests or Fisher exact test as appropriate. Cost data were compared with Mann-Whitney nonparametric test. RESULTS: There were 65 midshaft femur fractures in 63 patients included. TENs accounted for 77% and plating 23%. There were no statistical differences in injury severity score, length of stay, length unstable fractures, open fractures, fluoroscopy time, or pain. However, there was a significantly greater operative time (P=0.007) and a notably greater EBL (P=0.057) for the plating technique compared with TENs. Patient outcomes were found to be equivalent. Implant cost was not significantly different although increased surgical costs were seen in plating (P=0.0007). CONCLUSIONS: This study supports the use of TENs or plating for midshaft femur fractures in children 5 to 11 years old, regardless of length stability. The use of plates resulted in higher EBL, longer operative time, increased cost, and equivalent pain compared with TENs. To our knowledge, this study represents the first direct comparison of the common fixation methods specifically for midshaft femur fractures and favors the use of TENs. LEVEL OF EVIDENCE: Level III.

Negative allosteric modulators that target human alpha4beta2 neuronal nicotinic receptors.

Allosteric modulation of neuronal nicotinic acetylcholine receptors (nAChRs) is considered to be one of the most promising approaches for therapeutics. We have previously reported on the pharmacological activity of several compounds that act as negative allosteric modulators (NAMs) of nAChRs. In the following studies, the effects of 30 NAMs from our small chemical library on both human alpha4beta2 (Halpha4beta2) and human alpha3beta4 (Halpha3beta4) nAChRs expressed in human embryonic kidney ts201 cells were investigated. During calcium accumulation assays, these NAMs inhibited nAChR activation with IC(50) values ranging from 2.4 microM to more than 100 microM. Several NAMs showed relative selectivity for Halpha4beta2 nAChRs with IC(50) values in the low micromolar range. A lead molecule, KAB-18, was identified that shows relative selectivity for Halpha4beta2 nAChRs. This molecule contains three phenyl rings, one piperidine ring, and one ester bond linkage. Structure-activity relationship (SAR) analyses of our data revealed three regions of KAB-18 that contribute to its relative selectivity. Predictive three-dimensional quantitative SAR (comparative molecular field analysis and comparative molecular similarity indices analysis) models were generated from these data, and a pharmacophore model was constructed to determine the chemical features that are important for biological activity. Using docking approaches and molecular dynamics on a Halpha4beta2 nAChR homology model, a binding mode for KAB-18 at the alpha/beta subunit interface that corresponds to the predicted pharmacophore is described. This binding mode was supported by mutagenesis studies. In summary, these studies highlight the importance of SAR, computational, and molecular biology approaches for the design and synthesis of potent and selective antagonists targeting specific nAChR subtypes.