| Popis: |
The pelvis is a stable structure comprising of paired hemipelves. A thick layer of muscles covers the pelvis almost completely, leaving only a few bony prominences in a subcutaneous position. In order for this stable and well protected structure to be fractured, severe external violence must be applied. This trauma is due to road traffic accidents in the majority of cases. Fractures of the pelvis are common and constitute 20 to 30% of all fractures seen in veterinary practice. Despite this, the canine and feline pelvis has not been well studied. Little information is available regarding fracture locations, frequency of particular anatomical sites and overall severity of the pelvic disruption. The majority of pelvic fractures are surgically managed but there is a lack of accessible data regarding optimal fixation methodologies, the potential hazards and the rate of complication. There is also a difficulty in the assessment of concomitant pelvic soft tissue damage. A review of the topographical canine musculature and cross sectional anatomy was carried out and an attempt was made to provide a correlation with image based registration extended field of view ultrasound. For the cross sectional study, greyhound type canine cadavers were sectioned transversely and radially. Lines, correlating to the lines of section on the cadavers were drawn on a live greyhound. These lines were used as markers for the ultrasound transducer to be scanned along. For the topographic study, extensive dissection was carried out in order to identify the pelvic musculature and to see if it was present in agreement with standard anatomical textbooks. The corresponding individual muscles were scanned on a live greyhound. It was found that although the ultrasonography demonstrated the cross sectional anatomy, it was difficult to identify individual muscles. Whereas, when the individual muscles and muscle groups were scanned a clearer picture was produced. It was hoped that as the normal pelvic anatomy was accurately displayed using this technology then it might have potential as a diagnostic tool for rapid exploration of clinical cases subjected to trauma. The second part of the cross sectional study was carried out using both canine and feline cadavers, to try and localise safe, hazardous, and unsafe corridors for external skeletal fixation pin insertion. In a selection of dog and cat cadavers, sections were prepared. Although this gave a clear indication of the complexity of the pelvic anatomy, it was difficult to deduce the exact external skeletal pin insertion site from these sections. Greater success was attained through extensive dissection and the use of anatomy textbooks and an atlas. Three safe and three hazardous corridors were found in each hemipelvis. Although this part of the study is at present theoretical, it seems at this stage that external fixation of the pelvis is a plausible method of fracture fixation. The blood supply to the pelvis was also investigated. This part of the study was divided in to two broad categories: observations of the nutrient foramina and arterial casting. There was a tremendous amount of variation of the positions and sizes of the pelvic nutrient foramina. Foramina were divided subjectively into principal (the largest) and secondary, and this was further subdivided into large and small. All results were recorded diagrammatically. Only a few principal foramina were notably present in the majority of specimens. Many authors maintain that pelvic fractures heal rapidly due to the abundant blood supply but to date no demonstration of this has been found. Methylmethacrylate casting of the pelvic arteries clearly demonstrated the extensive pelvic vascular tree. In conjunction with the major and well-documented arteries, there were also dense arborisations of small vessels that would have lain between or within the musculature of the pelvis and proximal hindlimb. A retrospective radiographic study was carried out. The main goal of this study was to elucidate which pelvic fractures were the most common in small animals. There is a lack of information in the literature pertaining to this. It was hoped that the information gained would aid in the future in the design and production of treatment protocols, especially for those locations damaged most often. |
