Dowel pinning in phalangeal fractures

The objective of this case series was to report the outcome of a new technique for the surgical treatment of phalangeal fractures in cats and dogs. Medical records of cats and dogs presented with phalangeal fractures and treated with dowel pinning were retrospectively reviewed. Cases were included when a clinical examination and a radiographic follow-up evaluation of at least 6 months were available. Complications during the healing period and the final radiographic and functional outcome were analysed. Two cats and six dogs fulfilled the inclusion criteria. Closed fractures of a single phalanx predominated. All fractures were diaphyseal, transverse and displaced. Malunions occurred in two dogs. Complete functional union was achieved in all cases at the final follow-up. In conclusion, Dowel pinning was found to be an effective treatment for displaced, diaphyseal fractures of the proximal and the middle phalanx and a viable alternative to digit amputation

Occurrence of tympanic bone spicules and bone crests in domestic cats

Small and hyperostotic tympanic bone spicules (STBS and HTBS) extending from the tympanic wall or from the septum bullae into the tympanic cavity have been described in large feline species such as Siberian tigers or African lions and in canids such as dogs, red foxes and wolves. Detailed descriptions of prevalence, location and orientation were performed for dogs and African lions by means of necropsy and conventional computed tomography (cCT). Aims of the current study were to describe same characteristics for domestic cats by means of microcomputed tomography (µCT) and cCT. A total of 15 cats or rather 30 ears were examined. Furthermore, new bone formations extending into the tympanic cavity shaped like small lamellae were found and named “tympanic bone crests” (TBCs). The registered phenomenon of a thickened tympanic wall in some cats was named “tympanic wall thickening” (TWT). STBS appeared in 43% of the ears being bilateral in 44% of the cases, whereas HTBS appeared in one ear. TBC was present in 33% of the ears with a bilateral prevalence of 67%, and TWT could be detected in 13% of the ears. The mentioned structures are just barely or not at all detectable with cCT; therefore, µCT is necessary for an identification and detailed description. The origin and the factors inducing the development of examined phenomena are unknown, and it is hypothesized that the occurrence can be assessed as anatomical norm variations

In Vivo Degradation Behavior of the Magnesium Alloy LANd442 in Rabbit Tibiae

In former studies the magnesium alloy LAE442 showed promising in vivo degradation behavior and biocompatibility. However, reproducibility might be enhanced by replacement of the rare earth composition metal "E" by only a single rare earth element. Therefore, it was the aim of this study to examine whether the substitution of "E" by neodymium ("Nd") had an influence on the in vivo degradation rate. LANd442 implants were inserted into rabbit tibiae and rabbits were euthanized after 4, 8, 13 and 26 weeks postoperatively. In vivo μCT was performed to evaluate the in vivo implant degradation behaviour by calculation of implant volume, density true 3-D thickness and corrosion rates. Additionally, weight loss, type of corrosion and mechanical stability were appraised by SEM/EDS-analysis and three-point bending tests. Implant volume, density and true 3-D thickness decreased over time, whereas the variance of the maximum diameters within an implant as well as the corrosion rate and weight loss increased. SEM examination revealed mainly pitting corrosion after 26 weeks. The maximum bending forces decreased over time. In comparison to LAE442, the new alloy showed a slower, but more uneven degradation behavior and less mechanical stability. To summarize, LANd442 appeared suitable for low weight bearing bones but is inferior to LAE442 regarding its degradation morphology and strength

In Vivo Corrosion of Two Novel Magnesium Alloys ZEK100 and AX30 and Their Mechanical Suitability as Biodegradable Implants

In magnesium alloys, the components used modify the alloy properties. For magnesium implants in contact with bone, rare earths alloys are commonly examined. These were shown to have a higher corrosion resistance than other alloys and a high mechanical strength, but their exact composition is hard to predict. Therefore a reduction of their content could be favorable. The alloys ZEK100 and AX30 have a reduced content or contain no rare earths at all. The aim of the study was to investigate their in vivo degradation and to assess the suitability of the in vivo μCT for the examination of their corrosion. Implants were inserted in rabbit tibiae. Clinical examinations, X-rays and in vivo μCT scans were done regularly. Afterwards implants were analyzed with REM, electron dispersive X-ray (EDX), weighing and mechanical testing. The in vivo μCT is of great advantage, because it allows a quantification of the corrosion rate and qualitative 3D assessment of the corrosion morphology. The location of the implant has a remarkable effect on the corrosion rate. Due to its mechanical characteristics and its corrosion behavior, ZEK100 was judged to be suitable, while AX30, which displays favorable degradation behavior, has too little mechanical strength for applications in weight bearing bones

Compressive hydrated nucleus pulposus extrusion in a dog

An 8-year-old female neutered Maltese Bichon Frise was presented to a small animal hospital for assessment of acute paraplegia. Diagnostic imaging including plain spinal radiographs and CT angiography was neither suggestive of an intervertebral disc extrusion nor any other abnormalities could be detected. The dog was referred to the emergency service of a specialty hospital for an MRI scan. The MRI showed features of a hydrated nucleus pulposus extrusion (HNPE) at L2-3. Subsequent hemilaminectomy identified a mixture of white gelatinous and partly firm material. Cytology and histology were consistent with a partially degenerated nucleus pulposus. Compressive HNPE of the lumbar spine was diagnosed. The dog was discharged 5 days postoperatively. At the last follow-up conducted by phone interview (2 months postoperatively), the owner reported normal ambulation without any signs of neurologic deficits

Suitability of Permanent Probe Implants For the Measurement of Intramedullary Perfusion and Temperature Near the Bone Cortex: A Pilot Study Using a Rabbit Model

This study was conducted to test the suitability of permanent probe implants for the measurement of  intramedullary perfusion by laser Doppler flowmetry and for the measurement of temperature near the  bone cortex. Measurements were carried out on the conscious animal in order to rule out the influence of  anaesthesia on intramedullary perfusion and temperature. During the first experimental animal trials, some  of the probes made of polysulphon broke and/or gave false temperature measurements, so the original  probe design was modified. The probes were reinforced with metal, and the temperature sensors were made  less permeable to moisture. These modified probes were found to be suitable for permanent measurement  of intramedullary perfusion and of temperature near the cortex in the conscious rabbit.