Unifocal internal and external bone lengthening with circular external skeletal fixator in 5 dogs

The purpose of this study was to investigate the effectiveness of treatment of long bone defects and extremity shortness in 5 dogs using circular external skeletal fixator. In one case a bone necrosis and osteomyelitis shortened radius by 7.0 cm; however in others extremity shortening between 3.0 and 6.0 cm affected radius-ulna or tibia. 2 or 3 rings of 80.0-100.0 mm diameters, and 3 rods were used as a circular external skeletal fixator. The distractions at the rate of 0.5 mm X 2 times/day were performed following a latent period of 3 days after the corticotomy. Unifocal internal lengthening for case 1 and unifocal external lengthening for the others were performed. Distraction was performed between 30 and 70 days (mean 50 days). It was noted that the circular external skeletal fixator was well-tolerated in all cases. The first usages of limbs in all cases were on postoperative day between 8 and 43 (mean 22 days). The radiographic follow-up examinations revealed a complete consolidation on postoperative day between 35 and 75 (mean 55.6 days). The fixators were removed on the postoperative day between 45 and 85 (mean 65 days). The treatment was successful in restoring the appropriate length of the limbs. After removing the fixator, functional and cosmetic results were graded as excellent in 3 cases, good in one case and fair in one case.     

Treatment of radius-ulna and tibia fractures with circular external skeletal fixator in 19 dogs

This study was carried out on 19 dogs of different breed, age and sex. 10 different types of radius-ulna and 9 tibia fractures were treated by circular external skeletal fixator. The cases were followed by clinical and radiological controls in the postoperative period. It was observed that the cases tolerated the apparatus well. There was no looseness of fixator stability and configuration during the 15-day interval examination. Complications like pin track, serous drainage and pin loosening were observed postoperatively. It was concluded that radiographic, clinical and anatomical data together with good preoperative planning, the Ilizarov Method and circular external skeletal fixator was successful for the treatment of open or closed fragmented radius-ulna and tibia fractures in dogs.     

Use of a circular external skeletal fixator for stabilization of a comminuted diaphyseal metatarsal fracture in an alpaca

CASE DESCRIPTION: A 3-year-old male alpaca was evaluated because of non-weight-bearing lameness (grade 5/5) in the left hind limb. CLINICAL FINDINGS: Clinical and radiographic examination revealed a closed, comminuted, nonarticular, displaced diaphyseal fracture of the left third and fourth metatarsal bones. TREATMENT AND OUTCOME: Initial attempts at treatment via reduction of the fracture under traction and subsequent application of a cast were unsuccessful, and more stable fracture fixation was pursued. The alpaca underwent closed reduction of the fracture, which was stabilized by the application of a 3-ring circular external skeletal fixator (CESF). Improved weight bearing on the affected limb was evident soon after surgery and gradually increased; full weight bearing was evident by the seventh day after discharge from the hospital (day 20 after application of the CESF). Lameness was hardly noticeable during walking at that time. After 3 months, complete fracture healing was evident and the CESF was removed; mild outward rotation of the distal fragment and metatarsophalangeal joint was present. A Robert Jones bandage was applied to the limb, and the alpaca was kept in a stall for another 4 weeks. Eleven months after CESF application, the owners and referring veterinarian reported that the alpaca was healthy, not lame, and serving as a stallion without apparent impediment. CLINICAL RELEVANCE: Although mostly restricted to small animals, application of a CESF can be a viable alternative for management of long bone fractures in South American camelids.     

Biomechanical evaluation of acrylic external skeletal fixation in dogs and cats.

Acrylic external skeletal fixators (ESF) were compared with Kirschner ESF in biomechanical tests. A 2-cm unilateral acrylic ESF was found to be superior to medium Kirschner ESF in compression and shear loads. Acrylic ESF performed as well as Kirschner ESF in torsion loads. Acrylic ESF were used on 11 dogs and cats for repair of long bone fractures, for arthrodesis, or for immobilization of joints following ligament or tendon surgery. There were no complications associated with the use of acrylic ESF. Acrylic ESF offers the advantage of reduced cost, improved versatility, and simplified application technique when compared with Kirschner ESF.     

Type 1B external fixation of a metacarpal fracture in an alpaca

External skeletal fixation can be used in small ruminants as a successful, economic, alternative to internal fixation. In this case report, a type 1B frame was used on an alpaca to salvage a comminuted metacarpal fracture after failed internal fixation. Positioning the frame on the caudal aspect of the limb allowed full carpal flexion for kneeling and hence normal use of the limb throughout the recovery period. Complete healing occurred without further complications.     

Effects of static fixation and dynamization after interlocking femoral nailing locked with an external fixator: an experimental study in dogs

OBJECTIVE: To determine bone healing at 20 weeks, after either static fixation (SG) or after dynamization (DG) at 4 weeks in osteotomized canine femurs repaired with an interlocking nail (ILN) secured with a type I external skeletal fixator (ESF). STUDY DESIGN: Experimental study. ANIMALS: Ten adult beagle dogs. METHODS: After mid-diaphyseal femoral osteotomy, femurs in 10 dogs were repaired with an ILN secured with 4 (2 proximal, 2 distal) threaded custom pins (TP; 2.7-mm-diameter cortical screw with a 2-mm shaft attached to the screw head) to which 2 parallel connecting bars were attached in a type I ESF configuration. In 5 dogs, dynamization was performed at 4 weeks by removing the connecting bars and 2 distal screws. Limb function, range of motion of the stifle joint (ROMSJ), radiographic evidence of bone healing, and complications were studied for 20 weeks. RESULTS: Full limb function was achieved between 8 and 10 weeks in SG dogs, but a decreased ROMSJ was observed from 5 to 8 weeks. In DG dogs, full limb function occurred between 5 and 6 weeks except in 1 dog, and ROMSJ was considered normal in all dogs. Bone healing was not affected by dynamization. Average healing time for SG was 12.8 weeks, and for DG it was 13.6 weeks. Periosteal reaction at TP insertion points, osteolysis around the thread and head of TPs were observed in both groups. A windshield-wiper effect was observed at the tip of 1 ILN. CONCLUSION: ILN locked with a type I ESF can be used for fixation of mid-shaft femoral fractures. Dynamization at 4 weeks did not affect bone healing but did prevent stifle ankylosis and promoted earlier limb function. CLINICAL RELEVANCE: ILN locked with a type I ESF is seemingly a feasible method for repair of mid-shaft femoral fractures and may decrease risk of nail failure.     

Nonlinear increasing axial gap stiffness in type II external skeletal fixation: a mechanical study

OBJECTIVE: To quantify the effect on gap stiffness and cranial to caudal bending stiffness of conversion of the 6 distal clamps of planar bilateral fixator models to sliding clamps and the effect of attachment of composite beams to the sliding clamp models. STUDY DESIGN: Mdash;Mechanical testing performed on models. SAMPLE POPULATION: Five models using birch dowels and a commercially available external skeletal fixator system. METHODS: A segmentally comminuted, middiaphyseal fracture was simulated with the use of wooden dowels, and a bilateral 6-pin fixator was applied to create each of 5 models. The models were mechanically tested with all fixed clamps, with the 6 distal clamps converted to sliding clamps and with composite beams attached to the sliding clamp models. Testing was carried out in axial loading with physiologically relevant loads for a canine model, and in bending in the cranial to caudal plane. RESULTS: Sliding clamp fixators with composite beams attached exhibited a nonlinear increase in axial loading gap stiffness as load increased. The composite beam group also exhibited an increase in cranial to caudal bending stiffness as compared with fixed clamp and sliding clamp models. CONCLUSIONS: Using composite beam elements, planar bilateral external fixators can be constructed such that the fracture site would undergo controlled amounts of displacement at low loads and lessening displacement at higher loads. CLINICAL RELEVANCE: The nonlinear stiffness profile attained by the addition of composite beam elements to a planar external fixator allows controlled axial micromotion at the fracture site. Because controlled axial micromotion appears to stimulate fracture healing, a nonlinear stiffness profile of this type should enhance fracture healing.     

Delimitation of safe corridors for the insertion of external fixator pins in the dog 1: Hindlimb

Anatomical dissections of fresh canine hindlimb specimens were carried out on the femoral region and crus and cross sections of the crus to identify the location of safe corridors for external skeletal fixator pin insertion. Safe, hazardous and unsafe corridors were defined and measured along the canine hindlimb. Recommendations are made on the safe and effective use of fixator frames in the canine femur and tibia, in order to avoid potentially serious complications. No safe corridors were identified in the canine femoral region. The canine tibia is an eccentric bone and its entire medial aspect and part of its cranial aspect lie in a subcutaneous position. These areas are identified as safe for external skeletal fixator pin insertion.     

Mechanical comparison of an interlocking nail locked with conventional bolts to extended bolts connected with a type-IA external skeletal fixator in a tibial fracture model

OBJECTIVE: To compare the structural properties of interlocking nails (ILNs) locked with bolts (ILNb) to ILN locked with extended bolts connected with a type-IA external skeletal fixator (ILN-ESF) in a fracture gap model. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Synthetic tibial bone substitutes. METHODS: Custom-made synthetic tibial bone substitutes were implanted with standard ILNs locked with either bolts or extended bolts connected to an external skeletal fixation (ESF). Constructs were tested in torsion, bending, and axial compression (n=4/testing mode). Data, consisting of construct compliance and associated deformation, were compared using t-tests. RESULTS: The ILN-ESF construct compliance and deformation were significantly less than those of the ILNb construct in torsion, bending, and compression (P<.001). Slack was present in the ILNb construct under torsion and bending, but not in the ILN-ESF construct, regardless of testing mode. CONCLUSIONS: Substitution of locking bolts with extended bolts connected to an ESF significantly reduced the construct compliance and overall deformation in torsion, bending, and compression. Furthermore, the inherent slack of the ILNb was eliminated by the use of an ESF in torsion and bending. CLINICAL RELEVANCE: The improvement in structural properties of the ILN-ESF constructs could diminish interfragmentary motion at the fracture site and potentially improve bone healing.     

Management of a proximal pelvic limb skin laceration in a dog using a skin flap and an external fixator

A nine-year-old, spayed female crossbred dog sustained a traumatic skin lesion to the right proximal pelvic limb, extending to the extensor surface of the stifle. Surgical management of the wound included primary closure using a body skin flap fashioned from the right caudolateral abdominal wall. To achieve closure and prevent tension on the wound, the coxofemoral and stifle joints on the affected side needed to be immobilised in flexion. Flexion immobilisation of the stifle was achieved using the anatomical principle of muscle reciprocation. The ipsilateral tarsal joint was immobilised in flexion using a uniplanar-bilateral (type II) transarticular external skeletal fixator and this resulted in the automatic flexion of the stifle. The fixator was removed six weeks postoperatively when the wound had healed. There were no apparent complications associated with the fixator either during its use or in the longer term following its removal.     

Biomechanical comparison of a circular external skeletal fixator construct to pin and tension band wire fixation for the stabilization of olecranon osteotomies in dogs: a cadaveric study

OBJECTIVE: To compare anatomic reduction and the biomechanical properties of a circular external skeletal fixator (CESF) construct to pin and tension band wire (PTBW) fixation for the stabilization of olecranon osteotomies in dogs. STUDY DESIGN: Cadaveric study. ANIMALS: Forelimbs from 12 skeletally mature mixed-breed dogs, weighing 23 to 28 kg. METHODS: An olecranon osteotomy was stabilized with either a CESF construct or PTBW fixation. A single distractive load to failure was applied to each specimen through the triceps tendon. Osteotomy reduction and biomechanical properties were compared between fixation groups. RESULTS: Reduction was not significantly different (gap: P =.171; malalignment: P =.558) between fixation groups. Osteotomies stabilized with the CESF had greater stiffness (P <.0001) and maximum load sustained (P <.0001) compared to PTBW fixation. There was no significant difference for yield load (P =.318) or for load at 1 mm of axial displacement (P =.997) between fixation groups. Failure of fixation occurred by bending of the intramedullary Steinmann pin and the fixation wires in the CESF specimens and by untwisting of the tension band wire knot with pullout and bending of the Kirschner wires in the PTBW specimens. CONCLUSIONS: Specimens stabilized with the CESF construct had similar reduction and yield load, greater stiffness and maximum load sustained, and less elastic deformation than specimens stabilized with PTBW fixation. CLINICAL RELEVANCE: The CESF construct may provide a biomechanically favorable alternative to PTBW fixation for stabilization of olecranon osteotomies in dogs, and its application warrants clinical investigation.     

Use of an external skeletal fixation device and bone graft for arthrodesis of the metacarpophalangeal joint in horses

Arthrodesis of the metacarpophalangeal joint was attempted in 9 adult horses, using a new external skeletal fixation device and autogenous cancellous bone graft. Four horses had excellent results, 2 horses had fair results, arthrodesis failed in 2 horses, and 1 horse fractured the third metacarpal bone. The advantages of the technique included minimal surgical trauma to the area of injury, immediate rigid fixation of the metacarpophalangeal joint, and access for treatment of soft-tissue lesions at the site of injury. Although pin loosening and pin-track infection were complications when the device was in place, all pin tracks healed without complications after device removal.     

The use of a circular external skeletal fixation device for the management of long bone osteotomies in large ruminants: an experimental study

The study was undertaken to evaluate the feasibility of a simple, inexpensive model of circular external fixator (CEF) for use in large ruminants. A simple model of CEF frames consisting of four full rings (13-19 cm diameter, 4 cm wide and 4 mm thick with 18-24 holes) connected by threaded rods (8 mm diameter, 10-15 cm long) and nuts was developed using mild (low carbon) steel and were nickel-plated. In the first phase of the study, three male cow calves were utilized to study the feasibility of application of the fixators in the metatarsus, tibia and radius, in reference of adaptation and tolerance by animals. In the second phase, the fixators were tested in osteotomized bones. Six bull calves of 1.5-2 years of age weighing about 200-250 kg were utilized for this purpose. After preparing the area for aseptic surgery, under xylazine (at 0.1 mg/kg, i.m.)-ketamine (i.v. till effect) general anaesthesia, the test bone (metatarsus, radius and tibia in two animals each) was approached through the medial surface and an osteotomy was created with a saw and chisel at the mid-diaphysis. The pre-constructed 4-ring CEF was mounted on the limb around the test bone in such a way that it formed a cylinder with the axis of the limb at the centre. Each ring was then fixed to the bone with a pair of beaded wires (316 SS) of 3.5 mm diameter. During the post-operative period, the animals were observed for any change in behaviour, tolerance of the fixators, the weight bearing on the test limb, the status of the fixator, and the level of reduction of the osteotomy, alignment and healing at different intervals. The fixation of CEF was easier in the metatarsus and radius than in the tibia. The inner ring diameters found adequate for metatarsus, radius and tibia were 13-15 cm, 15-17 cm and 17-19 cm, respectively. The fixators applied to different bones were well-tolerated, and the animals could lay down, stand and walk freely with the fixator without any problems. All the animals showed good weight bearing in the immediate post-operative period. Weight bearing, however, slightly reduced in the inflammatory period and showed improvement after about 4 weeks. Wire tract infection was seen in all the animals, which was more on proximal wire tracts on lateral aspect of limbs. Circular fixators were well-tolerated by all the animals, and there was no breaking/bending of connecting rods, slotted bolts or the rings at any stage of observation. Slight bowing of some wires was noticed in cases of tibia and radius (in phase II) and bending of some wires was noticed from first week in two animals one each in radius and tibia. Bone fragments were well maintained until healing occurred (appearance of bridging periosteal callus) at 60-70 days. The functional results were good in all but one case of tibia, where a mal-union was recorded. From this study, it can be concluded that CEF are well-tolerated by large ruminants and can be used to treat long bone fractures. The fixator assembly using mild steel is sufficiently strong to maintain fracture fixation and is inexpensive. The simple design of the CEF appears to be sufficient to treat simple diaphyseal fractures of the metatarsus and radius. Improvement in the technique of fixation and design-like coupling of linear and circular fixator components into hybrid constructs may help to provide greater rigidity in treating tibial and open long bone fractures.     

Effects of two adenoviruses (type 1 and type 8) on functional properties of bovine alveolar macrophages in vitro.

Cultures of bovine alveolar macrophages were inoculated with type-1 and type-8 adenoviruses, initially isolated from calves with respiratory tract disease, and functional properties of the cells were observed over a period of 10 to 11 days. Both viruses replicated in macrophages; viral titers were low (less than 3.75 log10 TCID50/0.1 ml), and intranuclear inclusions were detected by indirect immunofluorescence in 5 to 10% of the cells from 3 days after inoculation. Highest titers were induced by type-1 adenovirus, which also induced the greatest functional changes. Expression of Fc and complement receptors was reduced by both viruses, although the greatest effects were seen with type 1. Phagocytosis of Candida krusei cells was reduced following type 1 infection, whereas phagocytosis in type-8-infected cells was not different from that of noninfected macrophages. Ability to kill ingested Candida cells also was reduced following type-1 infection, whereas type-8-infected macrophages had lower killing ability only at 2 to 4 days after inoculation. Neither virus had substantial effects on the production of neutrophil chemotactic factors by the macrophages.     

羊血清中口蹄疫病毒非结构蛋白3A-3B1-3B2抗体ELISA检测方法的建立

为建立检测羊血清中口蹄疫病毒非结构蛋白抗体的间接ELISA方法,通过优化抗原表达条件,在大肠杆菌原核表达系统中获得了可溶性的3A-3B1-3B2融合蛋白,基于纯化的可溶性融合蛋白建立了口蹄疫病毒非结构蛋白抗体间接ELISA检测试剂盒。该方法对其他相关的羊类病毒病原无交叉反应,其重复性组内与组间变异系数均低于10%,具有良好的重复性。对300份临床血清样品进行检测,与国内市售的口蹄疫非结构蛋白抗体检测试剂盒进行比较,阳性样品符合率为96.67%,阴性样品符合率为94%,总符合率为95.33%。本研究建立的羊血清中口蹄疫病毒3A-3B1-3B2蛋白抗体间接ELISA检测方法,特异性高、敏感性强,操作简单快速,具有较高的应用推广价值。     

Leukotriene C4 release and gene expressions of IL-8 and MCP-1 in porcine alveolar epithelial type II cells

Leukotrienes (LT) and chemokines are important chemotactic compounds in regulating the recruitment and activation of immune cells during pulmonary inflammatory reactions. Results showed that LTC4 release by porcine alveolar epithelial type II cells (AEC IIs) is significantly enhanced by either LTB4 or LPS stimulation. The basal level of IL-8 gene expression in AEC IIs was only 1/3 of that observed in alveolar macrophages (AMs) while AEC IIs expressed a higher basal level of monocyte chemotactic peptide-1 (MCP-1) and also in response to LPS stimulation than do AMs. The increasing basal and LT-induced MCP-1 gene expressions after 8h of incubation were observed in AEC IIs but decreased in AMs. These findings suggest that AEC IIs play an important role in initial inflammatory reactions of the lung by releasing LTC4, and that they also modulate later inflammatory reactions, evidenced by consistent elevation of MCP-1 gene expression after and during exogenous challenge in pigs.