Comminuted long bone fractures in cats caused by pneumatic gun shot and repaired using the external fixator "tie-in" technique

Five cats with femoral fractures caused by pneumatic gun shot wounds were treated using intramedullary pin/external skeletal fixation "tie-in" (IM/ESF tie-in) technique between 1997 and 2005. Clinical and radiographical examinations were used to assess bone healing, limb function recovery and complications. Clinical results as well as fracture healing were excellent in all five cats. The study showed that the IM/ESF tie-in technique can be used in cats for the treatment of comminuted femoral fractures caused by pneumatic bullets.     

Stifle joint luxation in the cat: treatment using transarticular external skeletal fixation

Extra-articular suturing techniques and transarticular external skeletal fixators were used to repair traumatic luxation of the stifle joint in four cats. Rupture of the cranial cruciate, caudal cruciate and medial collateral ligaments, together with injury to one or both menisci, were the most common injuries observed. The method of stifle repair was successful in all cases, but serious complications occurred when cats with transarticular external fixators were not kept confined indoors. Complications consisted of pin loosening and disruption of the fixator, or fractures through proximal or distal pins. Transarticular external skeletal fixation was considered to be a simple and effective method of maintaining short-term joint stability to allow healing of injured soft tissue structures. The apparatus facilitated early weightbearing and, on removal, allowed for the return of near-normal stifle function. Careful pin insertion and owner compliance in enforcing confinement are essential in minimising complications associated with immobilising the stifle joint using transarticular external skeletal fixation.     

Recent advances in external skeletal fixation

While the use of external skeletal fixation was once associated with substantial postoperative morbidity, clinical and experimental studies have led to technological advances and modifications in application techniques that have greatly improved the results obtained with this treatment modality. The past decade saw numerous advances in external skeletal fixator implants, components and instrumentation, including improvements in fixation pin design, and the development of new linear external skeletal fixation systems and economical circular external skeletal fixation systems specifically engineered for use in dogs and cats. In addition, a greater understanding of fixator biomechanics and the pathobiology of the bone-fixation pin interface have improved fixator application practices. This article reviews many of the more significant recent advances in external skeletal fixation.     

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.     

Management of femoral fractures in dogs with unilateral semicircular external skeletal fixators

Objective: To report use of semicircular external skeletal fixators (ESF) for management of femoral fractures in dogs. Study Design: Prospective clinical study. Animals: Dogs (n=16) with femoral fractures (n=18). Methods: A semicircular ESF system composed of 6‐hole 45° or 5‐hole 40° carbon‐fiber arches, 6 mm threaded rods, half pin fixation bolts, 6 mm nuts, and negative profile end‐threaded half pins were used for open repair of femoral fractures. ESF configuration, complications, limb use, fixator removal time, and functional outcomes were evaluated. Outcome was graded as excellent, good, fair, or poor. Results: Seventeen fractures with sufficient follow‐up healed. Eight dogs started using the limb immediately after waking up from anesthesia whereas initial limb use was 1–4 days after repair in the other dogs. Time to fixator removal ranged from 28 to 63 days (mean, 38 days). Functional outcome was excellent in 13 cases, good in 4, and poor in 1 nonunion. Conclusion: Semicircular ESF combined with open surgical reduction can be used to successfully repair metaphyseal and diaphyseal femoral fractures in young growing dogs.     

External skeletal fixation for stabilisation of comminuted humeral fractures in cats

Thirteen feline humeral fractures were stabilised using external skeletal fixation alone or in combination with supplementary devices. Eleven of the 13 fractures healed. Pins placed in the distal humerus should be angled to avoid the supracondylar foramen and radial nerve. An intramedullary pin in combination with external skeletal fixation is indicated for mildly comminuted reconstructable fractures. For severely comminuted humeral fractures, closed application of an external skeletal fixator may be preferable to open reduction and internal fixation to provide healing and is recommended as an alternative to amputation.     

Use of a hybrid external skeletal fixator for repair of a periarticular tibial fracture in a Patagonian cavy

An 8-week-old female Patagonian cavy was examined because of acute right hind limb lameness; radiography revealed a moderately displaced, comminuted fracture of the proximal third of the tibia. The fracture was stabilized with a hybrid external skeletal fixator. Two Kirschner wires were placed in the main proximal fragment, parallel to the tibial plateau and at right angles to each other. These wires were connected to a partial circular external fixator ring. Three half pins were placed in the distal fragment, and a straight connecting rod positioned on the medial side of the limb was connected to these pins and the fixator ring. A second connecting rod was positioned on the craniomedial side of the limb and was connected to the fixator ring and a fourth half pin in the distal fragment. The fracture healed without complications, and the fixator was removed 3 weeks after surgery. Hybrid external skeletal fixators combine the benefits of circular and linear external skeletal fixation methods, enabling rigid fixation of periarticular long bone fractures without adversely affecting mobility of the adjacent joint.     

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.     

Incidence of and predisposing factors for nonunion of fractures involving the appendicular skeleton in cats: 18 cases (1998-2002)

OBJECTIVE: To identify the most common sites of and possible predisposing factors for nonunions in cats with fractures of the appendicular skeleton. DESIGN: Retrospective study. ANIMALS: 344 cats treated for fractures between 1998 and 2002, 18 of which developed nonunions. PROCEDURES: Information collected from the medical records included signalment; type of trauma; fracture location, orientation, and type; degrees of displacement and comminution; treatment; and outcome. RESULTS: The tibia and proximal portion of the ulna were identified as the most common sites for nonunions. Factors significantly associated with development of a nonunion included age, body weight, affected bone, fracture type, degree of comminution, and fixation type, with older cats, heavier cats, cats with fractures of the tibia or proximal portion of the ulna, cats with open fractures, cats with comminuted fractures, and cats with fractures stabilized with a type II external skeletal fixator being significantly more likely to develop a nonunion. Eleven of the 18 cats with nonunions had a successful outcome following treatment of the nonunion. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that in cats, fractures involving the tibia and proximal portion of the ulna are more likely to develop nonunions than are fractures involving other sites but that many factors may increase the risk of nonunion. Use of excessively large and rigid type II external skeletal fixators may be associated with development of nonunions; however, type II external skeletal fixators were commonly used to stabilize fractures in sites predisposed to nonunion.     

Clinical application of an external fixator in the repair of bone fractures in 28 birds

The repair of seven tibiotarsal fractures, three humeral fractures, three tarsometatarsal fractures, two femoral fractures and 13 radial and ulnar fractures with a tubular external fixator system was evaluated prospectively in 10 common pigeons (Columba livia), 11 psittacine birds, six birds of prey and one Bali starling (Leucopsar rothschildii). The fixations included type 1, type 2 and intramedullary tie-in methods, and the fractures healed in all but three cases. A comparison of the weight of different connecting bars showed that the external fixation system and polymethylmethacrylate are the lightest available systems and that there was no clinically relevant difference between them.     

1例猫股骨头颈部骨折的诊断和治疗

犬猫单纯的股骨头颈部骨折临床上较少,其发病原因是骨盆或股骨受到直接或间接的外力导致,也常继发于髋关节发育不良导致的骨质疏松,轻微的外力就可造成动物的股骨头颈部骨折。介绍了猫股骨头颈部骨折的临床症状、诊断及治疗过程,以供参考。     

Fractures of the humerus.

A single or double bar, type I, unilateral external fixator can be used as primary or ancillary treatment for repair of many humeral fractures. Treatment of contaminated and comminuted fractures with external skeletal fixation provides rotational stability and axial alignment, access for wound management and bone grafting, and avoidance of vascular compromise by surgical invasion. In addition, the combination of external and internal (IM pins, cerclage wires, plates) fixation can provide greater initial fracture stability and subsequent dynamization or loading of bone (as the fixator is removed) than either of the systems used individually.     

Use of IMEX SK-circular external fixator hybrid constructs for fracture stabilization in dogs and cats

Complex long-bone fractures with short juxta-articular fracture segments can be difficult to manage. Recently, IMEX Veterinary, Inc., began producing titanium hybrid rods that can be secured to ring components of the IMEX circular external skeletal fixation system to create SK-circular hybrids. In this case series, SK-circular hybrids were used to stabilize long-bone fractures (two femoral, one humeral, and three tibial fractures) with short distal bone segments in three dogs and three cats with body weights ranging from 1.9 to 15 kg (mean, 6.7 kg; median, 5.4 kg). Although three cases required surgical revision, animals ambulated well and all fractures obtained union. Time to radiographic union ranged from 62 to 137 days (mean, 90 days; median, 84 days). The functional outcome was considered excellent in all six cases.     

Fractures of the femur.

The most common indications for the use of ESF in femoral fractures are closed transverse, short oblique, and minimally comminuted fractures in the central one third of the bone. External skeletal fixation is usually used in combination with IM pins and wiring techniques. During the process of open reduction and internal fixation, the surgeon should strive for accurate anatomic alignment and stability at the fracture site. The fixator is applied after the internal fixation is in place and the surgical wound is closed. The number of fixation pins placed in each fracture fragment depends on the type of fracture and the stability gained by internal fixation. Partially threaded fixation pins are recommended. They are inserted through skin stab incisions with low-speed power equipment. Recent modifications of the Type Ia fixator may increase fixator rigidity. Important postoperative concerns include exercise restriction, pin tract care, and protection of the fixator from the environment. Complications associated with ESF can be minimized by realizing its indications and limitations.     

Maxillomandibular external skeletal fixation in five cats with caudal jaw trauma

Five cats with caudal jaw injuries including mandibular ramus fractures, temporomandibular luxation/subluxation and temporal bone fractures were managed with external skeletal fixation to provide open-mouth maxillomandibular fixation. Three of five cats were able to eat orally during the period of fixation, whereas two cats with jaws fixed in a suboptimal position were dependent on oesophagostomy tube nutrition. Fixation was well tolerated and was maintained for 21 to 42 days. All cats were eating normally and had good jaw function at follow-up (mean 39 months, range 7 to 71 months).     

Femoral neck fractures and capital epiphyseal separations in cats

In a retrospective study, 47 fractures of the femoral neck and 17 capital epiphyseal separations were recorded in a total of 62 animals over a 12-year period. It was found that cats sustain femoral neck fractures more often than capital epiphyseal separations. Until cats are six months old the vast majority of lesions in the proximal femur are fractures of the neck. Between the ages of six and 12 months both lesions are equally represented. After 12 months of age no capital epiphyseal separations occur and the incidence of femoral neck fractures diminishes appreciably. If left untreated, an acceptable clinical result can be obtained in both femoral neck fractures and capital epiphyseal separations, although the best functional result is achieved in femoral neck fractures. In the present study, spontaneous healing was seen only in femoral neck fractures in cats younger than three months. All cats with capital epiphyseal separations developed hypertrophic pseudoarthrosis.     

Use of a circular external skeletal fixator for stifle arthrodesis in a dog

Arthrodesis of the right stifle was performed in a 21 kg German shepherd dog that had sustained a comminuted fracture of the lateral femoral condyle as a result of a gunshot wound. The arthrodesis was stabilised with a circular external skeletal fixator. A simplified technique to facilitate creation of the osteotomies of the femur and tibia, and positioning of the stifle at the desired angle, is described. Compression of the subchondral bone surfaces of the distal femur and proximal tibia was achieved using tensioned coiled transarticular Kirschner wires. Arthrodesis of the stifle was confirmed radiographically 21 weeks following surgery, and the fixator was removed. After union of the arthrodesis and removal of the fixator, the dog was fully weightbearing when standing or walking, and intermittently weightbearing or non-weightbearing at faster gaits.     

Closed fluoroscopic-assisted spinal arch external skeletal fixation for the stabilization of vertebral column injuries in five dogs

Objective— To evaluate outcome after closed fluoroscopic-assisted application of spinal arch external skeletal fixators in dogs with vertebral column injuries.
Study Design— Retrospective case series.
Animals— Dogs with traumatic vertebral column injuries (n=5).
Methods— Medical records of dogs with vertebral column fractures and/or luxations stabilized with spinal arch external skeletal fixator frames applied using a closed fluoroscopic-assisted technique were reviewed. Owners were contacted to obtain long-term clinical outcomes.
Results— Five dogs (age range, 6–72 months; weight, 10–54 kg) had traumatic vertebral column injuries stabilized with spinal arch external skeletal fixators applied in closed fashion. Injuries involved vertebral segments of the thoracolumbar junction, lumbar spine, and lumbosacral junction. Immediately postoperatively, 4 dogs had anatomic alignment of their vertebral fracture/luxation; 1 dog had 1 mm of vertebral canal height compromise. Time to fixator removal ranged from 65 to 282 days (141±87 days). All dogs had regained satisfactory neurologic function by 3 months. At long-term follow-up (range, 282–780 days; mean 445±190 days) all dogs were judged to have good to excellent return of function by their owners.
Conclusion— Successful closed fluoroscopic-assisted application of external skeletal fixators using spinal arches provided satisfactory reduction with few complications in 5 dogs. Return to function was judged to be good to excellent in all dogs at long-term evaluation.
Clinical Relevance— Closed fluoroscopic-assisted application of ESF using spinal arches provided satisfactory reduction and effective stabilization of spinal fractures with few complications and should be considered as a treatment approach.     

Spontaneous femoral capital physeal fractures in adult cats: 26 cases (1996-2001)

OBJECTIVE: To determine clinical, radiographic, and histologic abnormalities in adult cats > 1 year old with spontaneous (ie, nontraumatic) femoral capital physeal fractures. DESIGN: Retrospective study. ANIMALS: 26 cats. PROCEDURE: Medical records of cats > 1 year old with femoral capital physeal fractures and no history of trauma were examined. RESULTS: Mean +/- SD age of the cats was 22.5 +/- 6.5 months. Twenty-five cats were neutered males. Mean weight of the cats was significantly greater than mean weight of a group of age- and sex-matched control cats. Of 16 cats for which age at the time of neutering was known, 14 had been neutered before 6 months of age. Nine cats had bilateral fractures. Severity of femoral neck osteolysis and sclerosis increased with increased duration of clinical signs. The contralateral femoral capital physis, distal femoral physes, and proximal tibial physes were radiographically open in 13 of 18,19 of 24, and 24 of 24 cats, respectively. Histologically, the epiphysis contained normal articular cartilage and bone, but attached growth plate cartilage lacked the normal columnar arrangement of chondrocytes. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that adult cats with spontaneous femoral capital physeal fractures were most likely to be heavier, neutered males with delayed physeal closure.     

Use of a new investigational interlocking nail supplement in the repair of comminuted diaphyseal tibia fractures in two dogs

Two dogs were diagnosed with highly comminuted diaphyseal tibial fractures following traumatic incidents. Investigational hybrid interlocking nail (ILN) bolt/external skeletal fixator (ESF) pins were used to repair both fractures. The surgery was successful, and fractures healed without complications by 6 weeks (case no. 1) and 17 weeks (case no. 2) after surgery. This article describes the application and the advantages of a new, investigational ILN supplement that was specifically designed to accomplish initial rigid stability and allow progressive destabilization to the fracture repair. The authors are continuing to study the biomechanical properties of this procedure in order to accurately establish clear recommendations for its use in certain fracture situations.