Comparison of the effects of two screw insertion patterns on bone fragment translocation in a 3.5 mm dynamic compression plate and a 3.5 mm limited-contact dynamic compression plate.

OBJECTIVE: To compare the effects of screw insertion pattern, plate type, application of bone reduction forceps, and additional load screw insertion in an 8-hole 3.5 mm dynamic compression plate (DCP) and limited-contact dynamic compression plate (LC-DCP) on bone fragment translocation (BFT) in a fracture gap model. STUDY DESIGN: In vitro mechanical study. METHODS: Two screw insertion patterns were tested in the DCP and newly redesigned LC-DCP using gap model synthetic bone constructs. In Pattern 1, screws were first inserted into the holes at each end of the plate, then screws were inserted into the holes adjacent to the fracture gap. In Pattern 2, screws were only inserted into the holes adjacent to the fracture gap. The effects of tight or loose bone forceps securing the plate, loosening a neutral screw in Pattern 1, and inserting up to 4 additional load screws with each pattern were tested. Changes in the fracture gap were measured after insertion of all neutral screws and after each load screw. RESULTS: Pattern 2 BFT was significantly greater than Pattern 1 BFT when bone forceps were loose with both plates (P < .001). In the DCP, the BFT was significantly increased by loosening the bone forceps with Pattern 2 (P < .001) and by loosening 1 neutral screw in Pattern 1 (P < .001). The BFT for each additional load screw inserted was significantly less than 1.0 mm. CONCLUSIONS: A tight neutral screw in the same bone fragment as the load screw or bone clamps that tightly secure the plate to the bone can limit BFT.

Successful treatment of necrotizing fasciitis in the hind limb of a great dane.

A 5-month-old, intact female Great Dane was presented for an acute onset of rapidly progressive lameness, severe pain, and diffuse swelling of the right hind limb. Ultrasound evaluation revealed echogenic fluid pockets extending along fascial planes of the right hind limb, from the proximal femur to the hock. Necrotic soft tissues were debrided, and closed-suction drains were placed. No foreign material was identified at surgery. Fluid culture identified a beta-hemolytic Streptococcus sp., and affected fascial histopathology was consistent with necrotizing fasciitis. Postoperatively, the puppy was managed with intravenous broad-spectrum antibiotics, local infusions of amikacin, and daily physical rehabilitation. Oral pentoxifylline was administered to treat bronchopneumonia and streptococcal toxic shock syndrome that developed secondary to necrotizing fasciitis. To our knowledge, this is the first report of a successfully managed case of beta-hemolytic, streptococcal, necrotizing fasciitis successfully managed after a single surgical debridement in combination with systemic broad-spectrum antibiotics, local amikacin infusion, active closed-suction drainage, daily cytology, massage, and passive range-of-motion exercises to maintain limb function.

Cardiopulmonary effects of intrathoracic insufflation in dogs.

This study was designed to quantify the effects of incremental positive insufflation of the intrathoracic space on cardiac output (CO), heart rate (HR), arterial pressure (AP), central venous pressure (CVP), and percent saturation of hemoglobin with oxygen (SPO2) in anesthetized dogs. Seven healthy, adult dogs from terminal teaching laboratories were maintained under anesthesia with isoflurane delivered with a mechanical ventilator. The experimental variables were recorded before introduction of an intrathoracic catheter, at intrathoracic pressures (IP) of 0 mm Hg, 3 mm Hg insufflation, and additional increments of 1 mm Hg insufflation thereafter until the SPO2 remained <85% despite increases in minute volume. Finally the variables were measured again at 0 mm Hg IP. The cardiac output and systolic and diastolic AP significantly (P < 0.05) decreased at 3 mm Hg IP. Significant decreases in SPO2 were seen at 10 mm Hg IP. Significant increase in CVP was noted at 6 mm Hg IP. Heart rate decreased significantly at 5 to 6 mm Hg IP but was not decreased above 6 mm Hg IP. Given the degree of CO decrease at low intrathoracic pressures, insufflation-aided thoracoscopy should be used with caution and at the lowest possible insufflation pressure. Standard anesthetic monitoring variables such as HR and AP measurements may not accurately reflect the animal's cardiovascular status.

Pulmonary thromboembolism associated with Blastomyces dermatitidis in a dog.

An 8-year-old, male castrated golden retriever presented for cough and increased respiratory effort. Radiographs revealed an alveolar pattern in the right caudal lung lobe and an opacity at the carina suspected to be enlarged tracheobronchial lymph nodes. The disease progressed to involve the right middle lung lobe. Cytopathology of a fine-needle aspirate and bronchoalveolar lavage fluid were nondiagnostic. Surgical removal of the right caudal lung lobe and biopsy of the perihilar lymph nodes revealed pulmonary thromboembolism and reactive lymph nodes. The dog died several days postoperatively, and necropsy revealed diffuse pulmonary thromboembolism. Additionally, Blastomyces dermatitis organisms were identified in a pyogranulomatous mass surrounding the trachea near the carina. In an extensive literature search, no reports of pulmonary thromboembolism associated with blastomycosis were identified. It is suspected that the inflammation secondary to blastomycosis caused the thromboembolism.