Evaluation of different getter substrates using two-dimensional gas chromatography with time of flight mass spectrometry.

While understanding hydrogen uptake by organic based getters such as 1,4-bis(phenylethynyl)benzene (DEB) combined with a palladium(0)bis(dibenzylideneacetone) (Pd(dba)2) catalyst is essential, another crucial element to understand is the decomposition of the DEB, Pd(dba)2, and/or substrate material. The breakdown of these materials may create unwanted volatiles, which may interact with and lead to deterioration of sensitive materials. Moreover, it is critical to understand if different substrates cause the getter and/or catalyst to degrade in different manners. Utilizing comprehensive two-dimensional gas chromatography (GC×GC) with time-of-flight mass spectrometry (TOFMS), the presence of volatiles located in the headspace of various DEB/Pd(dba)2 getter substrates is examined. These samples include a getter infused silicone foam, a hydrogenated getter infused silicone foam, an activated carbon getter pellet, and a hydrogenated activated carbon getter pellet. Application of Fisher ratio (F-ratio) analyses lead to the identification of several compounds that are generated or consumed through the hydrogenation process. These include benzene derivatives such as bibenzyl, benzaldehyde, and vinyl benzoate in the activated carbon pellets and 1,5-diphenyl-3-pentanone, toluene, styrene, and 1-1'(2-pentene 1,5-diyl)bis benzene in the silicone foams, and alkane/alkene derivatives such undecane, 4-tridecene, and decane in the activated carbon pellets and 2,6-dimethyl undecane in the silicone foams. Further comparison of the different hydrogenated getter substrates (e.g. activated carbon pellet and silicone foam) indicates that the different substrates alter the decomposition products created from the degradation of the DEB and Pd(dba)2.

Posttraumatic Arthritis After Intra-Articular Distal Femur and Proximal Tibia Fractures.

Posttraumatic arthritis (PTA) is a form of joint degeneration that occurs after physical trauma to a synovial joint. Development of PTA is multifactorial and results from mechanical damage at the time of trauma, a cell-mediated inflammatory response, and abnormal articulation due to persistent malalignment or joint instability. Although some risk factors may be unavoidable, preventing the development of PTA of the knee after intra-articular fracture (IAF) requires restoring anatomic articulation and alignment. Reconstruction with total knee arthroplasty is the treatment of choice for PTA and may be a useful primary treatment for IAF in some.

Reliability of the classification of proximal femur fractures: Does clinical experience matter?

BACKGROUND: Radiographic fracture classification helps with research on prognosis and treatment. AO/OTA classification into fracture type has shown to be reliable, but further classification of fractures into subgroups reduces the interobserver agreement and takes a considerable amount of practice and experience in order to master. QUESTIONS/PURPOSES: We assessed: (1) differences between more and less experienced trauma surgeons based on hip fractures treated per year, years of experience, and the percentage of their time dedicated to trauma, (2) differences in the interobserver agreement between classification into fracture type, group, and subgroup, and (3) differences in the interobserver agreement when assessing fracture stability compared to classifying fractures into type, group and subgroup. METHODS: This study used the Science of Variation Group to measure factors associated with variation in interobserver agreement on classification of proximal femur fractures according to the AO/OTA classification on radiographs. We selected 30 anteroposterior radiographs from 1061 patients aged 55 years or older with an isolated fracture of the proximal femur, with a spectrum of fracture types proportional to the full database. To measure the interobserver agreement the Fleiss' kappa was determined and bootstrapping (resamples = 1000) was used to calculate the standard error, z statistic, and 95% confidence intervals. We compared the Kappa values of surgeons with more experience to less experienced surgeons. RESULTS: There were no statistically significant differences in the Kappa values on each classification level (type, group, subgroup) between more and less experienced surgeons. When all surgeons were combined into one group, the interobserver reliability was the greatest for classifying the fractures into type (kappa, 0.90; 95% CI, 0.83 to 0.97; p < 0.001), reflecting almost perfect agreement. When comparing the kappa values between classes (type, group, subgroup), we found statistically significant differences between each class. Substantial agreement was found in the clinically relevant groups stable/unstable trochanteric, displaced/non-displaced femoral neck, and femoral head fractures (kappa, 0.60; 95% CI, 0.53 to 0.67, p < 0.001). CONCLUSIONS: This study adds to a growing body of evidence that relatively simple distinctions are more reliable and that this is independent of surgeon experience.

Longer Length of Stay Increases 1-year Readmission Rate in Patients Undergoing Hip Fracture Surgery.

BACKGROUND: Proximal femur fractures are prevalent among the elderly and associated with substantial morbidity, mortality, and early readmission. Early readmission is gaining popularity as a measure of quality of hospital care and can lower reimbursement. A better understanding of the patient and treatment characteristics associated with readmission may help inform program improvement initiatives. This study tested the primary null hypothesis that length of stay is not associated with higher rates of readmission within 30 days and 1 year in patients having operative treatment of a proximal femur fracture, accounting for discharge destination and other factors. METHODS: We performed a secondary analysis on a database of 1,061 adult patients, age 55 years or older, admitted for treatment of a proximal femoral fracture in an urban level 2 trauma center. Multivariable logistic and linear regression models were created to account for the influence of age, sex, race, BMI, American Society of Anesthesiologists score (ASA), fracture type (AO/OTA), fixation type, operating surgeon, operative duration, and discharge destination. RESULTS: In multivariable logistic regression analysis, treatment by surgeon 4 was independently associated with a lower 30-day readmission rate. Higher one-year readmission rate was associated with a longer length of stay, ASA class 3, 4 and 5. CONCLUSION: The observation that patients cared for by specific surgeons are more likely to experience readmission within one year of surgery for a fracture of the proximal femur, suggests that program improvements to identify and disseminate best practices might reduce readmission rates. LEVEL OF EVIDENCE: III.

Lower Bone Mineral Density is Associated with Intertrochanteric Hip Fracture.

BACKGROUND: A better understanding of how bone mineral density and vitamin D levels are associated with femoral neck and intertrochanteric hip fractures may help inform healthcare providers. We asked: 1) In patients age ≥ 55 years, is there a difference in quantitative ultrasound of the heel (QUS) t-score between patients with fractures of the femoral neck and those with fractures of the intertrochanteric region, accounting for other factors 2) In patients age ≥ 55 years, is there a difference in vitamin D level between those with fractures of the femoral neck and those with fractures of the intertrochanteric region, accounting for other factors? 3) Is there an association between vitamin D level and QUS t-score? METHODS: In this retrospective cohort study, 1,030 patients were identified using CPT codes for fixation of hip fractures between December 2010 and September 2013. Patients ≥ 55 years of age who underwent operative management for a hip fracture following a fall from standing height were included. Three orthopaedic surgeons categorized fracture type using patient radiographs. Upon hospital admission, QUS t-scores and vitamin D levels were determined. Descriptive statistics, bivariate analyses and multivariable regression were performed. RESULTS: Accounting for potential confounders, patients with lower QUS t-scores were more likely to have intertrochanteric femur fractures than femoral neck fractures. In a bivariate analysis, there was no association between vitamin D level and either fracture type. There was no association between vitamin D level and bone mineral density. CONCLUSION: Patients with lower bone density that fracture their hips are more likely to fracture in the intertrochanteric region than the femoral neck, but vitamin D levels are unrelated. Awareness of this association emphasizes the importance of bone mineral density screening to assist with intertrochanteric hip fracture prevention. LEVEL OF EVIDENCE: III.