Adjunctive fixation of the humeral epicondyle in a lateral condylar fracture model: Ex vivo comparison of pins and plates with a novel composite (AdhFix).

OBJECTIVE: To compare the biomechanical properties of using a novel composite construct (AdhFix) to an interfragmentary Kirschner wire or a reconstruction plate as adjunctive epicondylar stabilization in simulated lateral unicondylar humeral fractures. STUDY DESIGN: Cadaveric biomechanical assessment. SAMPLE POPULATION: Paired humeri harvested from skeletally mature dogs (14-41 kg), nine cadavers per group. METHODS: Simulated lateral unicondylar humeral fractures were stabilized with a transcondylar 4.5 mm cortical screw placed in lag fashion. Adjunct fixations consisting of a novel composite incorporating 2.7 mm cortical screws on one side, and either a 2.7 mm reconstruction plate or a 1.6 mm Kirschner wire on the contralateral side, were tested within paired humeri. Repaired humeri were axially loaded to failure and construct stiffness, yield load, and ultimate load were obtained from the load-deformation curves. RESULTS: In pairwise comparison, yield load was significantly higher for AdhFix group compared to the pin group, p = .016. No statistical significance was seen in the comparison between AdhFix group and the plate group, p = .25. CONCLUSION: Adhfix was mechanically superior to K-wires, and comparable to plate fixation, for adjunctive fixation in a lateral humeral condylar model. Our results support further investigation of the novel composite for adjunct fracture fixation in lateral humeral condylar fractures. CLINICAL SIGNIFICANCE: The novel composite tested may be a viable alternative for adjunct fixation of humeral condylar fractures, a technique that circumvents plate contouring.

Postoperative regurgitation in dogs after upper airway surgery to treat brachycephalic obstructive airway syndrome: 258 cases (2013-2017).

OBJECTIVE: To determine the incidence of and risk factors for regurgitation in dogs within 24 hours of surgical management of brachycephalic obstructive airway syndrome (BOAS). STUDY DESIGN: Retrospective single center study of dogs undergoing BOAS surgery over four years (2013-2017). ANIMALS: Two hundred fifty-eight client-owned dogs referred for surgical intervention for BOAS. METHODS: Electronic medical records were searched for dogs that had undergone surgery for BOAS at a UK specialist referral hospital. Data were assessed by using univariable binomial logistic regression; confounding factors were then identified in a multivariable model. RESULTS: There was an increase in the proportion of dogs that regurgitated while hospitalized preoperatively vs during the first 24 hours postoperatively, from 28 (10.9%) to 89 (34.5%), respectively (P < .0001). History of regurgitation (P = .017, odds ratio [OR] 2.539, 95% confidence interval [CI] 1.178-5.469) and age (P = .008, OR 0.712, 95% CI 0.553-0.916) were detected as risk factors for postoperative regurgitation. For every 1-year increase in age, the odds of experiencing postoperative regurgitation were reduced by 28.8%. CONCLUSION: Corrective surgery for BOAS was associated with a marked incidence of postoperative regurgitation. Younger dogs and those with a history of regurgitation were predisposed to postoperative regurgitation. CLINICAL SIGNIFICANCE: The increased frequency of regurgitation after surgical treatment of BOAS, especially in younger dogs, provides justification for counseling owners regarding this postoperative complication.

Cranial tibial fascia autograft for wound closure following hemipelvectomy in a cat.

A 13-year-old cat underwent an extensive caudal external hemipelvectomy to excise a soft tissue sarcoma affecting the left proximal thigh. The cranial tibial fascia was harvested from the ipsilateral limb following amputation and used as a free graft in the reconstruction of the resultant pelvic and abdominal wall defect. Wound healing was uncomplicated, and 6 months following surgery there was no evidence of tumor recurrence or loss of integrity of the abdominal wall or lateral rectal support. Key clinical message: The cranial tibial fascia appears to be an effective autograft tissue for reconstructive surgery and may be applicable for closure of extensive hemipelvectomy procedures performed for tumors affecting the femoral region.

Autogreffe de fascia tibial crânial pour la fermeture de plaie à la suite d'une hémipelvectomie chez un chat. Un chat âgé de 13 ans a subi une hémipelvectomie caudale extensive afin d'exciser un sarcome des tissus mous affectant la cuisse proximale gauche. Le fascia tibial crânial fut prélevé du membre ipsilatéral suite à l'amputation et utilisé pour la greffe dans la reconstruction du défaut restant de la paroi abdominale et pelvienne. La guérison de la plaie s'est faite sans complication, et 6 mois suite à la chirurgie il n'y avait aucune évidence de récurrence de la tumeur ou de perte d'intégrité de la paroi abdominale ou du support rectal latéral.Message clinique important :Le fascia tibial crânial semble être un tissu d'autogreffe approprié lors de chirurgie reconstructive et pourrait être applicable pour la fermeture de procédures d'hémipelvectomie extensive réalisées lorsque des tumeurs affectent la région fémorale.(Traduit par Dr Serge Messier).

Alloying and Doping Control in the Layered Metal Phosphide Thermoelectric CaCuP.

We recently identified CaCuP as a potential low cost, low density thermoelectric material, achieving zT = 0.5 at 792 K. Its performance is limited by a large lattice thermal conductivity, κL, and by intrinsically large p-type doping levels. In this paper, we address the thermal and electronic tunability of CaCuP. Isovalent alloying with As is possible over the full solid solution range in the CaCuP1-xAsx series. This leads to a reduction in κL due to mass fluctuations but also to a detrimental increase in p-type doping due to increasing Cu vacancies, which prevents zT improvement. Phase boundary mapping, exploiting small deviations from 1:1:1 stoichiometry, was used to explore doping tunability, finding increasing p-type doping to be much easier than decreasing the doping level. Calculation of the Lorenz number within the single parabolic band approximation leads to an unrealistic low κL for highly doped samples consistent with the multiband behavior in these materials. Overall, CaCuP and slightly Cu-enriched CaCu1.02P yield the best performance, with zT approaching 0.6 at 873 K.

Revisiting Solid-Solid Phase Transitions in Sodium and Potassium Tetrafluoroborate for Thermal Energy Storage.

In situ synchrotron powder X-ray diffraction (PXRD) study was conducted on sodium and potassium tetrafluoroborate (NaBF4 and KBF4) to elucidate structural changes across solid-solid phase transitions over multiple heating-cooling cycles. The phase transition temperatures from diffraction measurements are consistent with the differential scanning calorimetry data (∼240 °C for NaBF4 and ∼290 °C for KBF4). The crystal structure of the high-temperature (HT) NaBF4 phase was determined from synchrotron PXRD data. The HT disordered phase of NaBF4 crystallizes in the hexagonal, space group P63/mmc (no. 194) with a = 4.98936(2) Å, c = 7.73464(4) Å, V = 166.748(2) Å3, and Z = 2 at 250 °C. Density functional theory molecular dynamics (MD) calculations imply that the P63/mmc is indeed a stable structure for rotational NaBF4. MD simulations reproduce the experimental phase sequence upon heating and indicate that F atoms are markedly more mobile than K and B atoms in the disordered state. Thermal expansion coefficients for both phases were determined from high-precision lattice parameters at elevated temperatures, as obtained from Rietveld refinement of the PXRD data. Interestingly, for the HT-phase of NaBF4, the structure (upon heating) contracts slightly in the a-b plane but expands in the c direction such that overall thermal expansion is positive. Thermal conductivities at room temperature were measured, and the values are 0.8-1.0 W m-1 K-1 for NaBF4 and 0.55-0.65 W m-1 K-1 for KBF4. The thermal conductivity and diffusivity showed a gradual decrease up to the transition temperature and then rose slightly. Both materials show good thermal and structural stabilities over multiple heating/cooling cycles.

New sustainable ternary copper phosphide thermoelectrics.

The thermoelectric performance of ACuP (A = Mg and Ca) with abundant elements and low gravimetric density is reported. Both systems are p-type doped by intrinsic Cu vacancy defects, have large power factors and promising figures of merit, reaching zT = 0.5 at 800 K. This demonstrates that copper phosphides are a potential new class of thermoelectric materials for waste heat harvesting.

Evaluation of the use of intra-operative radiology for open placement of lag screws for the stabilization of sacroiliac luxation in cats.

OBJECTIVES: To assess the effect of intra-operative radiology on the quality of lag screw insertion for the management of sacroiliac joint luxations in cats. METHODS: In this retrospective single-centre study, the surgical, anaesthetic and imaging records of 40 screws (32 cats) placed with lag effect for management of sacroiliac luxation were reviewed. Postoperative radiographs were assessed for sacroiliac joint reduction, screw position, and sacral width purchased by each screw. Cases were divided into two groups according to the use of (IOR) or the absence of intra-operative radiology (NIOR). RESULTS: A total of 23 lag screws were placed with the aid of intra-operative radiology and 17 without. Three of the 23 screws placed in the IOR group exited the sacrum as opposed to eight of 17 screws in the NIOR group (p = 0.03). Mean sacral width purchased by the screws in the IOR group (70.8%) was also significantly higher (p = 0.002) than in the NIOR group (54.6%). Mean general anaesthetic times for unilateral and bilateral screw placement for the IOR group and NIOR group were not significantly different. CLINICAL SIGNIFICANCE: The use of intra-operative radiology can significantly improve the quality of lag screw insertion for the stabilization of sacroiliac luxations in cats, which should lead to a reduced incidence of postoperative screw loosening.