Selective breeding for short head conformation reduces the size of the nasal cavities to such an extent that intranasal structures grow aberrantly and malformed, leading to obstructed air conducting spaces. Intranasal airway obstruction of brachycephalic dogs may contribute to their exercise and heat intolerance because of impaired pulmonary ventilation and compromised thermoregulatory functions of the canine nose. Failure to address intranasal obstruction might be an explanation for lack of therapeutic success after conventional surgery for brachycephalic syndrome. Future consideration should be given to the diagnosis, management, and treatment of this newly described aspect of airway obstruction.
The purpose of this study was to evaluate the prevalence of intranasal mucosal contact points in brachycephalic and normocephalic dogs. In total, 82 brachycephalic dogs (42 pugs and 40 French bulldogs) were evaluated by rhinoscopy for their intranasal mucosal contact and 25 normocephalic dogs were evaluated as a control group. Of those, 162 brachycephalic nasal cavities were evaluable and 140 had contact between intranasal structures (87%). Intraconchal and septoconchal mucosal contact points were the most commonly detected sites of contact. French bulldogs had a significantly higher prevalence of mucosal contact and had 3 mean contact points compared with 1.7 mean contact points per nasal cavity in pugs. Septal deviations were present in 62% of brachycephalic dogs. In the control group, mucosal contact points were present in only 7 of 50 nasal cavities (14%), and septal deviations occurred in 16% of those cases. Contact point average was 0.1 in large and 0.3 in small normocephalic dogs. Intranasal mucosal contact was identified as a common and previously unreported problem in brachycephalic dogs. Numerous contact points reduce the lumen of the intranasal passageways and indicate potential intranasal obstruction. Affected dogs might benefit from removal of obstructing conchae, potentially using laser-assisted turbinectomy.
Objective The aim of this study was to compare the locking compression plate (LCP) with polyaxial locking system (PLS) using single cycle to failure 4-point bending test and to investigate the behaviour of PLS with screws inserted mono- and polyaxially using cyclic fatigue test in two bending directions.
Materials and Methods Tests were performed on bone surrogates in a fracture gap model. The 3.5 LCP and 3.5 PLS plates were tested in single cycle to failure. The 3.5 PLS plates with mono- and polyaxial screws were compared in a cyclic fatigue tests in two orthogonal directions. For both experiments, micro-computed tomography (CT) scans were performed pre- and post-testing to investigate the connections between the screw head and the plate hole. Means of forces and cycles needed to failure were statistically compared.
Results The PLS plates were on average 30% weaker than LCP plates. Mode of failure was plate bending in the single cycle to failure tests, and plate breakage in the cyclic fatigue tests. Neither screw breakage nor loss of the screw–plate interface occurred. Mono- and polyaxial constructs performed similarly when loaded in the same direction. Micro-CT revealed no additional internal cracks in the plates or screws after testing. It also showed for both PLS and LCP that there was only partial contact of the screw head with the plate hole.
Clinical Relevance PLS offers a durable locking system, even when the screws are placed polyaxially. The weaker bending properties of the PLS compared with LCP should be considered during preoperative planning.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.