The development of a systematic ultrasound protocol facilitates the visualization of foreign bodies within the canine distal limb

Ultrasonography is an excellent investigative tool that can assist with the diagnosis of soft tissue conditions. In human medicine, ultrasonography is a fundamental diagnostic tool for the investigation of suspected vegetal foreign bodies (VFB), with protocol-based ultrasonography providing increased accuracy compared to lesion-focused examinations. Protocol-based ultrasonography is an emerging tool within the veterinary field, however, compared to human medicine is not routinely employed. The objective of this study was to develop a systematic ultrasound protocol to examine the distal limb for the visualization of vegetal foreign bodies (SUEDVEG). A 12 MHz linear and an 18 MHz high-frequency small-footprint linear array transducer was used on cadaver forelimbs (n = 6) and hindlimbs (n = 6) with images obtained from three common foreign body locations within the distal limb; 1; the interdigital webbing, 2; the palmar/plantar aspect of the phalanges and metacarpus and 3; the dorsal region of the phalanges and metacarpus. From these images, a 13-step systematic musculoskeletal protocol was developed and utilized on eight clinical cases or 10 limbs that had signs typical of distal limb VFB to preliminarily validate the proposed method. Vegetal foreign bodies were successfully identified and retrieved in seven (n = 8) clinical cases with method steps 9 and 11 (orthogonal views) identifying the majority of VFBs. The described ultrasound method appears highly useful for visualizing soft tissue locations of the canine distal limb known for tracking foreign bodies. Further studies are required to validate the described systematic examination method as the preferred clinical protocol over currently used lesion-focused exploration techniques

Investigations into the mechanical performance of a locking plate and evaluation of models to examine cortical bone and periosteal vascular perfusion after plate fixation

Introduction Studying mechanical changes occurring during fracture repair with locking plates, and associated cortical-periosteal vascular changes, is vital for understanding bone healing. Methods Paired femora (n=6 pair) had conical coupling locking plates applied. One of each pair had a plate-bone distance (PBD): 0 mm and the other: 2 mm. Constructs were cyclically loaded to failure. Testing was repeated with aluminium tubing replacing bone, eliminating screw-bone cutout. All constructs were examined under stereo zoom and scanning electron microscope, at the screw-implant, screw-bone/metal interfaces. Blood flow in sheep cortical bone was assessed using stable isotope microspheres. Vascular mapping of the hind limb via contrast computer tomography (CT) and radiographic imaging was performed. The final in vivo study assessed two models for examining periosteal capillary perfusion beneath locking plates, with and without an ostectomy. CT and histological studies were performed. Results Biomechanical study: mean sustained loads in the 0 mm PBD group (420.8 Newtons, 7612 cycles) were significantly greater than in the 2 PBD mm group (337.5 Newtons, 4252 cycles) p<0.001. The conical coupling component of the locking mechanism did not uncouple. Cortical bone study: injecting stable isotope microspheres systemically and locally yielded inconsistent results. A critical review of procedures is needed. Periosteal study: New blood vessels were detected (not quantified), on histological examination. CT could not assess capillary perfusion. The design of a suitable study for examining periosteal capillary perfusion requires further evaluation. Conclusion Conical coupling locking plates can be elevated 2 mm from bone without uncoupling the locking mechanism. Capillary perfusion of the periosteum was identified qualitatively but not quantitatively. Examining ovine cortical and periosteal vascular perfusion requires further study to investigate the damage from screw placement

Safety evaluation of the Guardian device on the common carotid artery in sheep

Background: Pulse pressure intensity in middle-aged adults is a risk factor for dementia. The Guardian device (The Brain Protection Company, Sydney, Australia) has been developed to reduce pulse pressure, as a potential therapy. Objectives: The aim of this study was to evaluate the safety of the Guardian, a novel pulse modulation device designed to reduce the intensity of the pulse pressure that penetrates into the cerebral small vessels. The Guardian is a helix that gently wraps around the common carotid artery (CCA) to slightly change its shape, to absorb pulsatility, without lowering flow. Methods: The Guardian was implanted bilaterally on the CCAs of 10 mature sheep for chronic implant periods of 3, 6 or 8 months. The ratio of internal device diameter to outer diameter of the CCA varied from 63% to 92% (n = 20). The implant position on the vessel was marked surgically at implant. Gross pathology and histopathology of the CCA were examined at 3- and 6-months post explant. Most devices were explanted using open surgery, however minimally invasive surgical explant techniques were examined in 2 animals to assess the potential of this approach for explant in humans if required. Results: The Guardian was successfully implanted with no adverse events, and minimally invasive explant appeared to be viable for removal. Following implant, the device was surrounded by a thin fibrous capsule, with similar pathology at 3- and 6-months. Minimal or no movement was observed. CCA sections appeared histologically normal, with no evidence of thrombosis, stenosis, fibrosis, chronic inflammatory response, or vessel degeneration. Conclusions: The feasibility of surgical implantation and biomaterial safety of the Guardian was confirmed over 8 months. Minimally invasive explant of the Guardian has the potential to be viable. Further work is required to demonstrate efficacy in vitro and/or in vivo before evaluation in humans