Hydrothermal conversion of mixed uranium(IV)-cerium(III) oxalates into U1-xCexO2+δ·nH2O solid solutions.

Uranium-cerium oxide solid solutions, U1-xCexO2+δ·nH2O, were prepared through hydrothermal conversion of mixed U(IV)-Ce(III) oxalate precursors, cerium being used as a surrogate for plutonium. Whatever the starting pH, the fluorite-type structure of AnO2 was obtained after heating at 250 °C for 24 h. The initial pH of the reaction media appeared to affect significantly the oxide morphology: for pH ≤ 2, the powder was found to be composed of microspheres, whereas for more alkaline pH values, agglomerates of nanocrystallites were found. Furthermore, a study of the hydrothermal treatment duration (T = 250 °C, pH = 8, t = 1-48 h) showed that fluorite-type mixed dioxides started to form after only 1 h, and then became single phase after 3 h. SEM and TEM/EDS analyses revealed that the cationic distribution narrowed with time to finally form highly homogeneous mixed oxides. Such a preparation route was then applied to various cerium incorporation rates and it was found that the formation of U1-xCexO2+δ·nH2O mixed oxides was possible for 0.1 ≤ x ≤ 0.75. In all the systems investigated, the speciation of uranium and cerium was questioned in both the solid and liquid phases. Thermodynamic calculations and evaluation of the O/M ratio in the final oxides led us to understand the complex redox behaviour of uranium and cerium in solution during hydrothermal processes and to propose a conversion mechanism.

The true axial shoulder projection: Diagnostic aid for acromioclavicular joint dislocation?

INTRODUCTION: Acromioclavicular joint dislocations are common. Differentiating between horizontal and vertical instability is challenging, but possible to diagnose on axial radiographs. No clear consensus for axial radiograph parameters currently exists. We aim to establish a reproducible technique to assess whether an axial radiograph represents a true axial view of the shoulder. METHODS: One hundred CT scans of normal uninjured shoulders were examined using multiplanar reformatting to assess the distance between the anterior glenoid (reference line) and anterior-most aspect of the acromion in the axial plane. Measurements were repeated and performed by multiple observers to give of intra- and inter-observer reliability. RESULTS: The mean distance from the anterior acromion to the reference line was -2.6 mm (i.e. posteriorly placed) (SD = 5.8 mm, range -16.9-13.2 mm). Most (89%) of the measurements were between 9 and -9 mm to the reference line. Intra-observer reliability was high with Cronbach's α measurement as 0.997. Inter-observer reliability gave a Cronbach's α measurement of 0.959. CONCLUSION: When the anterior aspect of the acromion lies within 10 mm either side of a line parallel to the scapula blade at the anterior aspect of the glenoid on an axial radiograph, it represents a true axial projection of the glenohumeral joint (GHJ).Level of evidence: IV, Case series.

The treatment of perilunate ligament injuries in multiply injured patients.

PURPOSE: Perilunate injuries are rare, severe injuries of the carpus. They can present as isolated injuries or in the poly-traumatised patient. This is the first documented series of these injuries treated in a Major Trauma Centre. The aims were to assess the management, treatment algorithm and outcomes, of perilunate injuries in our department, review whether concomitant polytrauma affected those outcomes and identify if delay to definitive treatment had a significant effect on overall outcome. METHODS: Perilunate injuries admitted to the Royal London Hospital between Oct 2011 and March 2016 were identified. All definitive surgical procedures were performed by the senior author; hand therapists supervised patient rehabilitation. Outcomes were assessed by Mayo Wrist and QuickDASH scores. RESULTS: We identified 23 perilunate injuries (22 patients). There was an associated nerve injury in 10 cases with other system injuries present in 12 cases. At final review, the mean carpal height ratio was 0.56, Mayo Wrist score was 81 and QuickDASH score was 16.4. There were no differences when comparing the outcomes of patients who had early against those with more delayed definite treatment or when comparing patients with isolated wrist injuries against polytrauma patients. CONCLUSION: Satisfactory outcomes can be achieved, even in the presence of other injuries, if initial treatment is prompt and follows a clear management protocol. Prompt early reduction and neurological decompression followed by subsequent accurate definitive fixation leads to good outcomes. A delay of definitive fixation of up to 18 days does not appear to have a deleterious effect on outcome.

Assessment of penetration of dorsal screws after fixation of the distal radius using ultrasound: cadaveric study.

INTRODUCTION: Volar locking plates are used to treat unstable and displaced fractures of the distal radius. Potential advantages of stable anatomical reduction (eg early mobilisation) can be limited by penetration of dorsal screws, leading to synovitis and potential rupture of extensor tendons. Despite intraoperative imaging, penetration of dorsal screws continues to be a problem in volar plating of the distal radius. Ultrasound is a well recognised, readily available, diagnostic tool used to assess soft-tissue impingement by orthopaedic hardware. In this cadaveric study, we wished to ascertain the sensitivity and specificity of ultrasound for identification of protrusion of dorsal screws after volar plating of the distal radius. METHODS: Four adult, unpaired phenol-embalmed cadaveric distal radii were used. A VariAx™ Distal Radius Volar Locking Plate system (Stryker, Kalamazoo, MI, USA) was employed for instrumented fixation. A portable SIUI CTS 900 ultrasound machine (Providian Medical, Eastlake, OH, USA) was used to image the dorsal cortex to ascertain screw penetration. RESULTS: Specificity and sensitivity of ultrasound for detection of screw protrusion through the dorsal cortex was 100%. CONCLUSIONS: Ultrasound was found to be a safe and accurate method for assessment of dorsal-screw penetration through the dorsal cortex of the radius after volar plating of the distal radius. It also aids diagnosis of associated tendon disorders (eg tenosynovitis) that might cause pain and limit wrist function.

Severe brachial plexus injuries in rugby.

We describe the mechanisms, pattern of injuries, management and outcomes of severe injuries to the brachial plexus sustained during the play of rugby. Thirteen cases of severe injury to the brachial plexus caused by tackles in rugby had detailed clinical assessment, and operative exploration of the brachial plexus. Seventeen spinal nerves were avulsed, two were ruptured and there were traction lesions in continuity of 24 spinal nerves. The pattern of nerve lesion was related to the posture of the neck and the forequarter at the moment of impact. Early repair by nerve transfer enabled some functional recovery, and decompression of lesions in continuity was followed by recovery of nerve function and relief of pain.

Neuropathic pain following hip resurfacing due to a transneural suture.

A 60-year-old man developed severe neuropathic pain and foot-drop in his left leg following resurfacing arthroplasty of the left hip. The pain was refractory to all analgesics for 16 months. At exploration, a PDS suture was found passing through the sciatic nerve at several points over 6 cm and terminating in a large knot. After release of the suture and neurolysis there was dramatic and rapid improvement of the neuropathic pain and of motor function. This case represents the human equivalent of previously described nerve ligation in an animal model of neuropathic pain. It emphasises that when neuropathic pain is present after an operation, the nerve related to the symptoms must be inspected, and that removal of a suture or irritant may lead to relief of pain, even after many months.

Glenoplasty for complex shoulder subluxation and dislocation in children with obstetric brachial plexus palsy.

We describe the early results of glenoplasty as part of the technique of operative reduction of posterior dislocation of the shoulder in 29 children with obstetric brachial plexus palsy. The mean age at operation was five years (1 to 18) and they were followed up for a mean of 34 months (12 to 67). The mean Mallet score increased from 8 (5 to 13) to 12 (8 to 15) at final follow-up (p < 0.001). The mean passive forward flexion was increased by 18° (p = 0.017) and the mean passive abduction by 24° (p = 0.001). The mean passive lateral rotation also increased by 54° (p < 0.001), but passive medial rotation was reduced by a mean of only 7°. One patient required two further operations. Glenohumeral stability was achieved in all cases.