Different fixation constructs and the risk of non-union following first metatarsophalangeal joint arthrodesis.

BACKGROUND: The aim of this study was to determine if a single or separate construct with interfragmentary screw was associated with higher rates non-union following first metatarsophalangeal joint (MTPJ) arthrodesis. METHODS: A retrospective analysis of patients undergoing first MTPJ arthrodesis between April 2010 and June 2017 was performed. Patients who received either a single (Stryker Anchorage 1 MTP Cross Plate) or separate (Stryker Anchorage 1 MTP locking plate with one Asnis partially threaded compression screw) construct locking plate and interfragmentary compression screw were reviewed. Descriptive statistics were generated for sample demographics and between-group differences were calculated. Multivariable regressions explored internal fixation type and association with non-union. RESULTS: A total of 280 first MTPJ arthrodesis met the inclusion criteria and were reviewed. The incidence of non-union was 7.9% of procedures (22 joints). Following multivariable binary logistic regression, the single construct locking plate with interfragmentary compression screw was associated with an increased risk of non-union (OR 3.43, 95% CI 1.26-9.33), adjusting for age, gender and comorbidity. CONCLUSIONS: A single construct interfragmentary screw and locking plate (Stryker Anchorage 1 MTP Cross Plate) was associated with an increased incidence of non-union following first MTPJ arthrodesis.

Pressure and temperature induced red-shift of the sodium D-line during HMX deflagration.

The sodium D-line is often present in optical spectra of combustion due to its high prevalence and emissivity. Collision theory predicts the spectral peak to have a red-shift dependent on pressure, P, and temperature, T. Here we show that the conditions reached during deflagration of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) permit the red-shift of the sodium D-line to be calibrated to 1.5 GPa. Deflagration at these pressures is achieved using a split Hopkinson pressure bar apparatus, with temperatures of circa 2900 K from the greybody continuum away from spectral features. Lower deflagration pressures, of 0.5 to 0.9 GPa, are achieved in a fallhammer test, with temperatures of circa 4000 K. The red-shift exhibits the predicted PT-0.7 dependence with a constant of proportionality of (950 ± 30) GPa-1 · K0.7 · nm. Using the serendipitous presence of sodium, this optical technique allows for fast measurements of both pressure and temperature from the same light source in one measurement.

Diagnostic techniques in deflagration and detonation studies.

Advances in experimental, high-speed techniques can be used to explore the processes occurring within energetic materials. This review describes techniques used to study a wide range of processes: hot-spot formation, ignition thresholds, deflagration, sensitivity and finally the detonation process. As this is a wide field the focus will be on small-scale experiments and quantitative studies. It is important that such studies are linked to predictive models, which inform the experimental design process. The stimuli range includes, thermal ignition, drop-weight, Hopkinson Bar and Plate Impact studies. Studies made with inert simulants are also included as these are important in differentiating between reactive response and purely mechanical behaviour.

One-pot conversions of olefins to cyclic carbonates and secondary allylic and homoallylic amines to cyclic carbamates.

Sequential treatment of a 1,2-disubstituted olefin with m-CPBA, Br3CCO2H, and DBU results in the one-pot, stereospecific conversion of the olefin to the corresponding disubstituted cyclic carbonate (1,3-dioxolan-2-one). The reaction proceeds via an initial epoxidation followed by S(N)2-type epoxide ring opening by Br3CCO2H and subsequent base-promoted carbonate formation upon elimination of bromoform. When a solution of a secondary allylic or homoallylic amine and Br3CCO2H is sequentially treated with m-CPBA then DBU, the product of the reaction is a cyclic carbamate (1,3-oxazolidin-2-one or 1,3-oxazinan-2-one).

Deep venous thrombosis in a child: an unusual presentation of an osteochondroma.

Deep vein thrombosis is very uncommon in the pediatric population. We describe an unusual case of deep vein thrombosis caused by a femoral osteochondroma in a 13-year-old adolescent girl with known multiple hereditary exostoses. We discuss the optimum investigations to determine the site of venous obstruction, which is crucial when there are several osteochondromata in the affected limb, which could be implicated in causing the obstruction to venous flow.