A unilateral external skeletal fixator (ESF) system with an acrylic connecting bar, combined with an intramedullary OX pin, was used to treat simple, comminuted and open fractures of the tibia in 12 clinical cases occurring in large and small dogs, and in cats. A minimal surgical approach was used in all cases, The I.M pin was placed first, in the normograde fashion, to align the tibial fragments, Transfixation pins were then inserted from the medial side, using previously published guidelines for safe corridors in the tibia (30), thus minimizing the potential for soft tissue trauma. An acrylic connecting bar was used in all of the cases, enabling connection of pins that were not in the some plane. All of the fractures healed uneventfully. This report shows that unilateral ESF with an acrylic connecting bar, combined with an I.M pin, is an effective method for the repair of a wide variety of tibial fractures.

This paper presents a three-dimensional biomechanical model of the canine hind limb, and describes the process of determining the muscle forces and joint reaction forces and moments occurring in the hind limb during three-legged stance. The model was based on anatomical and morphometric data presented in a previous paper. Equations of equilibrium were formulated for the different components of the hind limb. Since the number of unknowns exceeded the number of equations, the problem was statically indeterminate. 

Two optimization techniques were applied to solve this statically indeterminate problem. The resultant hip-joint reaction force (acting on the acetabulum) predicted by these optimization methods ranged between 0.73 and 1.04 times body weight, and was directed dorsally, medially and caudally. The resultant knee-joint reaction force (acting on the femur) ranged between 1.05 and 1.08 times body weight and was directed dorsally, laterally and cranially. The largest muscle forces predicted by the minimization of maximal muscle stress (MMMS) criterion were in the biceps femoris (0.24 times body weight), rectus femoris (0.15 time body weight), medial gluteal (0.18 times body weight), semi-membranous (0.09 times body weight), the lateral and intermediate vastus (0.18 times body weight) and the medial vastus (0.17 times body weight). The largest muscle forces predicted by the minimization of the sum of muscle forces (MSMF) criterion were in the biceps femoris (0.29 times body weight), lateral and intermediate vastus (0.45 times body weight), and the deep gluteal (0.16 times body weight). 

The magnitudes and directions of the forces in the joints of the canine hind limb, as well as in the muscles that surround these joints, provide a database needed for future biomechanical analyses of the physiology and pathophysiology of the canine hind limb. (C) 2002 Elsevier Science Ltd. All rights reserved.

Pulsed electromagnetic fields (PEMFs) have been found to be beneficial to a wide variety of biological phenomena. In particular, PEMFs have been shown to be useful in the promotion of healing of ununited fractures. Conflicting information exists regarding the benefit of using PEMFs to accelerate the healing of fresh fractures. This paper reports on the evaluation of the effect of a new PEMF generator (PAP IMI(R)) on the healing of fresh ulnar fractures in rats. This device is unique by virtue of the extremely high power output of each of the pulses it generates. Ulnar fractures were created in rats by using a bone cutter, thus producing a 2-3 mm bone defect. Rats were then randomly divided into treatment and control groups. The treatment group underwent periodic treatments with the PAP IMI(R), and the control group received no treatment. Radiographs of rats from both groups were taken at 1-week intervals. Histological evaluation was performed at the end of the study. Radiographic and histopathological evaluations were scored, and scores were used to assess both rate and quality of healing. The radiographic results demonstrated gradual bridging callus formation in both control and treatment groups, however, the healing process was faster in rats that were not treated by PEMF. Histological evaluation demonstrated that the fibrous content of the callus in rats belonging to the treatment group was significantly higher than that in rats belonging to the control group. The results of this study do not support the claim that PEMF generated by the PAP-IMI(R) stimulate osteogenesis and bone healing after the creation of fresh ulnar fractures in rats.

Objective-To obtain the anatomic and morphometric data required for biomechanical analysis of the hindlimb in dogs. 

Animals-A healthy adult mixed-breed 23-kg male dog. 

Procedure-Following euthanasia of the dog, all muscles of the right hind limb were identified and meticulously removed. Physiologic cross-sectional areas (PCSA) and architectural indices (Al) were calculated. The coordinates for the origin and insertion of each muscle were determined, using orthogonal right-handed coordinate systems embedded in the pelvis, femur, and tibia. 

Results-PCSA and Al were calculated for 29 muscles, and coordinates for the origins and insertions ofthese muscles were determined. 

Conclusions-Results provide the morphometric and anatomic data necessary for S-dimensional biomechanical studies of the hind limb in dogs.

The use of acrylic connecting bars in external fixators has become widespread in veterinary orthopaedics. One of the main advantages of an acrylic connecting bar is the ability to contour it into a curved shape. This allows the surgeon to place the transcortical pins according to safety and convenience considerations, without being bound by the requirement of the standard stainless steel connecting bar, that all transcortical pins be in the same plane. 

The purpose of this study was to evaluate the stiffness of unilateral and bilateral medium-sized external fixator frames with different curvatures of acrylic connecting bars. Finite element analysis was used to model the various frames and obtain their stiffness under four types of load: Axial compression, four-point medio-lateral bending, four-point antero-posterior bending and torsion. The analysis also provided the maximal pin stresses occurring in each frame for each loading condition. 

Based on the results of this study, curvatures of acrylic connecting bars of up to a maximal angular difference between pins of 25 degrees will result in very similar stiffness and maximal pin stresses to those of the equivalent, uniplanar stainless steel system. In both unilateral and bilateral systems the stiffness decreases slightly as angulation increases for axial compression and medio-lateral bending, increases slightly for torsion and increases substantially for antero-posterior bending.

Objective-To compare the stiffness and pin stresses of three sizes of external fixator systems with stainless-steel and acrylic connecting bars. 

Study Design-Finite element analysis. 

Methods-Small, medium, and large external fixator systems of type I and type II configurations were modeled for finite element analysis. Each model was evaluated with a standard stainless-steel and three different diameters of acrylic connecting bar. Displacements and stresses were calculated for the loading modes of axial compression, medio-lateral bending, cranio-caudal bending, and torsion. The location of the pin experiencing maximum stress was determined for all configurations and loading modes. 

Results-Acrylic column diameters of 9.53 mm for the small external fixator system and 15.9 mm for the medium external fixator system provide equivalent stiffness and maximum pin stresses to those provided by the standard stainless-steel connecting bars (3.2- and 4.8-mm diameter, respectively). The largest diameter acrylic column tested (31.75-mm) produced lower stiffness and higher maximum pin stresses than the standard stainless-steel connecting bar (11.1-mm diameter). 

Conclusions-When applying a small or medium external fixator, an acrylic column of 9.53-mm or 15.9-mm diameter, respectively, can be used. For a large external fixator system, an acrylic column of diameter >31.75 mm is required. 

Clinical Relevance-The sizes of acrylic connecting bars for use in small and medium external fixator systems have been determined. Large systems should incorporate the standard stainless-steel connecting bar. (C)Copyright 2000 by The American College of Veterinary Surgeons.

Suturing the esophagus after esophagotomy or esophageal resection and anastomosis can be problematic, and complications such as suture line breakdown, leakage, and stenosis are reported. This article discusses esophageal anatomy and physiology and complications associated with esophageal surgery, a history of suture methods used in esophageal surgery is also provided. A new suture technique is described and evaluated based on a retrospective study.

The technique and results of free skin grafts have been described in dogs, horses, rabbits, goats and mice, The procedure in cats is, however, described only indirectly in papers relating to dogs, A standard technique has been developed by the authors for use in cats, and is reported for 17 grafts in 16 cats with traumatic injury to the legs resulting in large areas of skin loss, This paper describes the preparation of the wound for grafting, the harvesting of the graft, graft placement, postoperative care and the results of the application of this technique. The success rate in this series of cases was high. This was attributed to proper preparation of the recipient site, collection of the graft and postoperative bandaging, The results suggest that the success rate of free skin grafts in cats is considerably higher than that achieved by the present authors in dogs, and reported for dogs by other surgeons in the literature.

Bite wounds of the chest wall in small dogs can extend into the thorax and can be associated with severe damage to chest wall muscles, ribs, and lungs. Two major problems associated with the management of these wounds are lack of sufficient muscle tissue for chest wall reconstruction, and difficulty draining the extensive dead space created in the chest wall. We describe a simple method to overcome these problems. The bite wound areas were surgically explored and all devitalized soft tissue was debrided. The pleural cavity was explored, intrathoracic injuries repaired, and a thoracic drainage tube was placed. Ribs in the injured area were stabilized in anatomic position by means of heavy gauge sutures passed around pairs of adjacent ribs, thus creating a scaffolding for soft tissues. Viable muscle and subcutaneous tissues were apposed as much as possible and the skin closed over the defect. Eleven small dogs were treated using this technique. All dogs had severe injuries to the thoracic wall muscles and eight dogs had multiple rib fractures. There was no evidence of chest wall instability in any of the dogs after surgery. Nine dogs survived the injury and were reevaluated 3 to 32 months after surgery. All were clinically normal. One dog developed wound infection and pyothorax, caused by insufficient debridement of injured muscle tissue, and died 10 days after surgery. A second dog died 24 hours postoperatively of undetermined causes. (C) Copyright 1997 by The American College of Veterinary Surgeons

Monoclonal antibody (MAb) CC49 binds to human tumour-associated glycoprotein termed TAG-72. CC49 is a second-generation MAb with higher affinity to TAG-72 than the original MAb B72.3. CC49 was applied to 42 samples from different canine mammary tumours, belonging to seven different histopathological types. Immunoreactivity was detected by the use of an avidin-biotin complex immunoperoxidase method. Most sections from all types of mammary neoplasm reacted with this MAb. Normal tissue did not stain or stained only weakly. The results of this study suggest CC49 has selective immunoreactivity for a variety of canine mammary tumours, which seems superior to that reported with MAb 72.3. These results support the proposal for further study of diagnostic and therapeutic uses of CC49 in the management of canine mammary tumours.

An alternative method for external coaptation of fractures in young animals utilizes tongue depressors incorporated in a bandage consisting of a thick layer of cotton padding, gauze bandaging, and adhesive tape. This method was used in 13 cases with fractures of the tibia or the radius and ulna, some of which were open, Five cases (four dogs and a cat) had displaced fractures, and eight cases had either nondisplaced or only mildly displaced fractures. Size of the animal was not considered a limiting factor Bandages were examined periodically, All fractures healed uneventfully and the splints were removed 21-to-44 days after application, This method of external coaptation proved to be easy to apply and modify during the healing process and was applicable to a wide variety of fractures with good results.