External Skeletal Fixation System Research Articles

Management of Long Bone Fractures Using Diverse Fracture Fixation Techniques in Small Animals

Total 11-cases of different breeds of dogs and one case of Persian cat having long bone fractures were successfully managed using totally intravenous anaesthesia (TIVA). For TIVA, combination of xylazine and ketamine were used for induction whereas sole ketamine was used for maintenance and atropine sulphate was used as preanaesthetic and anticholinergic agent. TIVA found suitable for orthopaedic surgeries in this study. Intramedullary pinning, bone-plating (Dynamic compression plating and Reconstruction plating), external skeletal fixation system (using jess clamps and epoxy) or combination of two different fracture fixation techniques were performed for surgical management of presented fracture cases. For combination of two orthopaedic techniques, either bone plating with supplementary IM-pinning or ESF with IM-pinning were used in this study. All cases were evaluated by radiographs as well as clinical performance of operated limbs. Radiographs were taken at regular interval for assessment of radiographic bone healing and in those cases where radiographs were not possible owner contacted telephonically.

The use of circular and hybrid external skeletal fixation systems to repair open tibial fractures in large ruminants: a report of six clinical cases.

A prospective clinical study consisting of six bovines (200-300kg body weight) undergoing open tibial fractures was carried out, to evaluate the use of circular and hybrid external skeletal fixation (ESF) systems for open tibial fracture repair in large ruminants. The ESF systems consisting of 4 full rings (n = 2), 8 half-rings (n = 1), 2 full rings with 2 sidebars (n = 2) or 2 full rings with 4 sidebars (n = 1) were used to treat open tibial fractures. The healing progress of the animals was evaluated based on different clinical and radiographic examinations. The level of fracture reduction, alignment, and fixation ranged between satisfactory to adequate in all the animals. The fixators were well tolerated and maintained by the animals till the complete repair of the fracture. Adequate fracture healing with satisfactory functional recovery was observed in all the animals in about 3-4months. The different designs of ESFs were found to provide adequate stability in open tibial fractures in animals weighing 200-300kg. However, the fixators need to be evaluated in numerous clinical cases to establish their suitability in routine clinical settings.

Acrylic and Epoxy-pin External Skeletal Fixation Systems for Fracture Management in Dogs

Background: The metallic ESF systems are not easily available in the field and have fixed frames leading to less versatility in size and direction. Free forms of external skeletal fixators (acrylic and epoxy-pin) have advantages as they can be customized. Both acrylic and epoxy-pin ESF systems have been evaluated biomechanically in earlier studies; in the present study both are compared clinically.Methods: Twenty four dogs presented with 27 fractures of long bones, were randomly divided into 4 groups, according to the bones involved, group A was divided into A-I (radius-ulna) and A-II (tibia-fibula) sub-groups and group B was divided into B-I (radius-ulna) and B-II (tibia-fibula) sub-groups.Result: The mean ± SE fracture healing time in animals was 48.85 ± 2.56 days with no significant difference between two groups.The early presented cases and the ones with less soft tissue trauma showed better gait scores during the follow up period. Both acrylic and epoxy-pin fixators provided stable fixation and the technique can be practiced at field conditions with minimal facilities. Epoxy-pin ESF owing to better handling characteristics of epoxy resin is easier to construct than the acrylic ESF.

External skeletal fixation of tibial fracture in a domesticated rabbit

Present case reports a successful diagnosis and surgical management fractured left tibia bone through linear external skeletal fixation system (LESF) in a 1.5 year old male rabbit. Surgery was performed under general anaesthesia. A Rabbit presented in Veterinary clinical complex, CVAS, RAJUVAS, Bikaner, with a history of fall from height and clinical as well as radiographic examination revealed compound, segmental fracture of diaphysis of left tibia bone. LESF was done and owner was advised for further follow-up at regular interval. ESF assembly as well as weight bearing status was evaluated as objective of this study.

Ectrodactilia en un Beagle: manejo quirúrgico

Se reporta el caso de un Beagle hembra de 5 meses con cojera del miembro anterior derecho y un defecto de separación entre el segundo y tercer dedo. En el examen radiográfico se observó hipoplasia del hueso carporradial y del segundo metacarpiano, y ausencia del primer dedo. Además, presentó una hendidura con contenido de tejido blando entre el segundo y tercer metacarpiano. Los hallazgos fueron compatibles con ectrodactilia unilateral. Se realizó una cirugía reconstructiva mediante una artrodesis pancarpal, con relleno de hueso esponjoso y utilizando un sistema de fijación esquelética externa. Se restableció completamente la función del miembro a las 10 semanas.

Radius and ulna fracture repair with the IMEX miniature circular external skeletal fixation system in 37 small and toy breed dogs: A retrospective study.

To determine outcome and prognostic factors after radius and ulna fracture repair with a modified IMEX miniature circular external skeletal fixation (MCESF) in small and toy breed dogs. Retrospective study. Thirty-seven young small and toy breed dogs with 41 radial and ulnar fractures. Records of radial and ulnar fractures repaired with a modified IMEX MCESF were reviewed. Constructs included 3-4 complete rings, 2 threaded rods, 4 mm-diameter nuts and 6-8 transfixation wires. MCESF configuration, type of fracture reduction, dynamization of the apparatus, inclusion of a dowel pin, and implantation of allograft were recorded. Outcome measures included complications, limb alignment, time to clinical union, and functional outcomes, scored as excellent, good, fair, or poor. Radiographic union was achieved in 40/41 fractures. Fractures reached bony union within 33-84 days after repair. Time to union was not influenced by the type of fracture reduction (P = .11), use of a dowel pin (P = .099), or implantation of an allograft (P = .45). Fracture dynamization delayed radiographic union (P = .0005). At implant removal, mean frontal (FPA) and mean sagittal plane alignments (SPA) were 7.9° ± 6.5° and 7.5° ± 5.8°, respectively. Limb alignment did not differ between radiographs obtained immediately after surgery and those obtained at time of radiographic union in the frontal (P = .062) or sagittal (P = .14) planes. Ninety-five percent of cases had good-to-excellent outcomes, based on return to function at final re-evaluations. This modified IMEX MCESF construct provided an effective alternative to treat young small and toy breed dogs with radius and ulna fractures.

Comparative Biomechanical Evaluation of Acrylic- and Epoxy-Pin External Skeletal Fixation Systems with Two- and Three-Point Fixation per Segment under Compressive Loading

Comparative Biomechanical Evaluation of Acrylic- and Epoxy-Pin External Skeletal Fixation Systems with Two- and Three-Point Fixation per Segment under Compressive Loading

In vitro biomechanical testing of a micro external skeletal fixator

To biomechanically test the properties of three different Universal Micro External Fixator (UMEX™) configurations with regard to their use in very small animals (<5kg) and compare the UMEX system to the widely used IMEX External Skeletal Fixation (SK™) system in terms of stiffness, space needed for pin placement and weight. Three different UMEX configurations (type Ia, type Ib, and type II modified) and one SK configuration type Ia were used to stabilize Delrin plastic rods in a 1 cm fracture gap model. These constructs were tested in axial compression, craniocaudal bending, mediolateral bending, and torsion. Testing was conducted within the elastic range and mean stiffness in each mode was determined from the slope of the linear portion of the load-deformation curve. A Kruskal Wallis one-way analysis of variance on ranks test was utilized to assess differences between constructs (p <0.05). The UMEX type II modified configuration was significantly stiffer than the other UMEX configurations and the SK type Ia, except in craniocaudal bending, where the SK type Ia configuration was stiffer than all UMEX constructs. The UMEX type Ia configuration was significantly the weakest of those frames. The UMEX constructs were lighter and smaller than the SK, thus facilitating closer pin placement. Results supported previous reports concerning the superiority of more complex constructs regarding stiffness. The UMEX system appears to be a valid alternative for the treatment of long-bone fractures in very small animals.

Correction of severe congenital flexural carpal deformities with semicircular external skeletal fixation system in calves

To present a novel technique for the treatment of severe congenital flexural forelimb deformities in calves. Thirteen calves of different breeds and sex with severe congenital flexural forelimb deformities were enrolled in the study. A semicircular external skeletal fixation system composed of 6-hole, 45° carbon-fiber arches, 6 mm threaded rods, half-pin fixation bolts, 6 mm hexagonal nuts, and negative profile end-threaded half-pins were used for pancarpal arthrodesis. Complications, time to first use of the limb, fixator removal time, preoperative and postoperative sagittal plane angles of the fused joints, and functional outcomes were evaluated clinically and radiographically. Final assessments were determined according to functional and cosmetic outcomes. All of the surgically treated carpal joints obtained fusion. Seven of the calves started to use the limb immediately after recovering from anesthesia. In the other six calves, the time ranged from one to two days. Time to fixator removal ranged from 25 to 36 days (mean 30 days). Final outcome was excellent in 11 cases, and good in two cases. The technique was found to be a useful method for the treatment of severe congenital flexural forelimb deformities in calves. The cost of the operation is negligible compared to the economic value of beef cattle.

Treatment of unilateral congenital flexural and torsional limb deformities with circular external skeletal fixation system in two calves

Two calves with unilateral congenital flexural and torsional limb deformities below the hock joint of the left hindlimb were presented to Veterinary Teaching Hospital of the Ondokuz Mayis University. According to clinical, goniometric and radiological examinations, flexural (130°-40°) and torsional (90°-180°) deformities were diagnosed. Except for the limb deformities, both animals were otherwise completely healthy. In case 1, hock joint arthrodesis was performed using a circular external skeletal fixation system with four full rings 160 mm in diameter. In case 2, the deformity was corrected by fixation after transverse osteotomy at the level of the proximal metatarsals with four full rings 150 mm in diameter, and arthrodesis of the fetlock joint with three full rings 100 mm in diameter. According to clinical examinations and follow-up telephone interviews performed 15 and 24 weeks after discharge, functional use with slight lameness in case 1 and full functional use in case 2 had been achieved. None of the previously reported cases of flexural deformity had radiographic signs similar to those of the calves in our report, and the deformities were not as severe as those reported here. To our knowledge, this is the first report of treatment of unilateral congenital flexural and torsional deformities in calves with a circular external skeletal fixation system.

Evaluation of delayed-image bone scintigraphy to assess bone formation after distraction osteogenesis in dogs

To quantitatively assess distraction-induced bone formation in a crural lengthening model in dogs by use of delayed-image bone scintigraphy. 12 mature Labrador Retrievers. Dogs were randomly allocated to 1 of 3 groups. A circular external skeletal fixation system was mounted on the right crus of each dog. Osteotomy of the distal portion of the tibia and fibula was performed in groups 1 and 2 and was followed by a lengthening procedure of 10 mm in the first group only. The third group served as sham-operated controls. Delayed-image bone scintigraphy with technetium-99m hydroxy methylene diphosphonate was performed 2, 4, and 6 weeks after surgery. Delayed-image-to-region-of-interest, delayed-image-to-crural, and delayed-image-to-femoral scintigraphic activity ratios were calculated. New bone formation was quantified by use of densitometric image analysis, and values for the scintigraphic ratios were compared. In the distraction and osteotomy groups, delayed-image-to-region-of-interest and delayed-image-to-crural ratios increased significantly. Although densitometric image analysis revealed increased bone formation after distraction, the region-of-interest ratios and crural ratios were similar in both groups. All dogs had increased delayed-image-to-femoral ratios. Delayed-image bone scintigraphy ratios were not effective at differentiating between the amounts of distraction-induced bone and osteotomy-induced bone. Metabolic bone activity in the adjacent femur was increased as a consequence of circular external skeletal fixator placement. Delayed-image bone scintigraphy was not adequately sensitive to quantitatively monitor bone formation but may be useful as an early predictor of bone healing.

Treatment of distal diaphyseal fractures using hybrid external skeletal fixation in three dogs

Stabilisation of distal diaphyseal/metaphyseal fractures or osteotomies of the tibia and the radius is challenging due to the small fragment size, with innovative implants and external skeletal fixation systems described for their management. Hybrid external skeletal fixation is a novel external fixation system for use in small animals. This case series describes the management of distal diaphyseal fractures with IMEX-SK hybrid external skeletal fixation in three canine patients. Fracture healing was achieved in all cases, with frame removal after 5 to 10 weeks. Minimal complications were encountered in two cases. IMEX-SK hybrid external skeletal fixation constructs provide the veterinary surgeon with another option in the management of distal diaphyseal/metaphyseal fractures.

Prognostic Factors in Treating Antebrachial Growth Deformities with a Lengthening Procedure Using a Circular External Skeletal Fixation System in Dogs

To evaluate treatment of antebrachial growth deformities (AGD) with a lengthening procedure using a circular external skeletal fixation (CESF) system and to determine prognostic factors. Prospective clinical study. Thirty-four dogs with unilateral AGD. Length deficits, angular and rotational deformities, elbow incongruity (EI), osteoarthritis (OA) of the elbow and carpal joint, function, and cosmesis were determined before and after a CESF lengthening procedure. On admission, EI (21 dogs; 62%), OA of the elbow joint (17 dogs; 50%), carpal OA (12 dogs; 35%), and concomitant elbow and carpal OA (5 dogs; 7%) were common findings. Treatment significantly improved function (normal, 20 dogs; 60%) and cosmesis (normal, 22 dogs; 65%). Angular and rotational deformities were almost completely corrected with small remaining length deficits. Elbow and carpal OA increased significantly during the follow-up period. Significant correlations were demonstrated between initial elbow OA and final function (R=0.42, P=.02), initial function and final function (R=0.41, P=.02), and initial ulnar and radial deficit and final cosmesis (R=0.58, P=.0001 and R=0.45, P=.008). Treatment of AGD by a CESF lengthening procedure was successful despite small remaining length deficits. Initial elbow OA, function, and ulnar and radial length deficits are prognostic factors in the treatment of AGD. Initial elbow OA and initial function are prognostic factors in predicting the functional outcome of treatment of AGD with a CESF lengthening procedure in the dog.

The efficacy of the bone markers osteocalcin and the carboxyterminal cross-linked telopeptide of type-I collagen in evaluating osteogenesis in a canine crural lengthening model

The aim of the present study was to determine the efficacy of the bone markers osteocalcin (OC) and carboxyterminal cross-linked telopeptide of type-I collagen (ICTP) in evaluating new bone formation in the dog, using commercially available immunoassay kits. Dogs were randomly divided into three groups and a circular external skeletal fixation system (CESF) was mounted on the tibia. In the first group a distraction osteogenesis procedure of the crus was performed. The second group received an osteotomy without crural lengthening, whereas the third group served as a sham-operated control. Bone formation was assessed using densitometric image analysis of crural radiographs. Despite significant differences in the amount of newly formed bone, this finding was not reflected in the plasma levels of OC and ICTP. In conclusion, OC and ICTP were not efficacious as markers of bone formation and resorption during osteogenesis in this canine model.

Utility of a modular external skeletal fixation system during panniculectomy.

A modular external skeletal fixation system was used as an adjunct during massive panniculectomy to control the soft tissue mass. This stable frame construct was found to readily transmit force vectors to the suspended soft tissue and aid in exposure during pannus resection. This system seemed to offer a mechanical advantage over penetrating pins alone.

Influence of the connecting rod on the biomechanical properties of five external skeletal fixation configurations

SummaryA recently developed external skeletal fixation system (SK™, IMEX Veterinary, Inc.) utilizes larger diameter connecting rods, therefore overcoming one of the weaknesses of the original Kirschner-Ehmer (KE) system. The purpose of the current study was to compare five typical external fixator constructs in axial compression, torsion, Cranial-Caudal (C-C) and Medial-Lateral (M-L) bending to determine the effect of the larger connecting rods on frame stiffness. The results demonstrate that the larger connecting rod has a significant effect on overall frame stiffness. The use of two or more full-pins, as in the type II and III techniques nullified the contribution of the connecting rod diameter and frame stiffness was more a factor of pin size, number and orientation.

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.

Validation of a finite element model of the Kirschner-Ehmer external skeletal fixation system

Abstract Objective To determine the validity of finite element analysis (FEA) as a means of examining biomechanical properties of the Kirschner-Ehmer external skeletal fixation system. Sample Population 10 paired tibiae harvested from skeletally mature dogs weighing between 30 and 38 kg immediately following euthanasia for reasons unrelated to musculoskeletal disease. Procedure A gap fracture was created in each bone; fragments were stabilized with 3 frame configurations (type I, type II, and type III), using enhanced-profile threaded pins. Each bone-frame construct was tested, using a materials testing machine in 3 modes of testing: axial compression (AC), mediolateral (ML) bending, and craniocaudal (CC) bending, for a total of 9 tests/bone. The elastic limit of the constructs was not exceeded during testing. Mean stiffness values were determined from load-displacement curves. A finite element model of each construct was created, using three-dimensional elastic beam elements, and stiffness values were calculated, using FEA. Correlations between experimental and FEA data then were determined. Results Significant differences in stiffness were seen among all 3 constructs in CC bending and AC, with stiffness increasing with construct complexity. No significant difference in ML bending stiffness was seen between type-II and type-III constructs; however, both were significantly stiffer than the type-I constructs. The experimental and FEA stiffness data were strongly correlated (AC, r = 0.994; ML bending, r = 0.998; CC bending, r = 0.985). Conclusions and Clinical Relevance Strong correlations among experimental and FEA data indicate that FEA is a valid method of comparing stiffness of Kirschner-Ehmer external skeletal fixation constructs. (Am J Vet Res 1999;60:615–620)

Initial Clinical Experience with the IMEX™ Circular External Skeletal Fixation System

SummaryThe IMEX™ Circular External Skeletal Fixation (CESF) System was used to treat 10 antebrachial deformities in nine dogs. The mandible of one dog with prognathism was also lengthened. Dogs ranged in age from four to 18 months (mean ± SD: 9 ± four months; median: eight months) and body weight from 2.6 to 46.0 kg (mean ± SD: 23.9 ± 11.2 kg; median: 24.2 kg). Linear distractions were performed with linear motors or threaded rods with paired nylon nuts securing the connecting rods to rings placed between ring blocks. Hinges and angular motors were used to correct angular deformities. A latency period of two to six days and a distraction rate of 1 mm/day, with a twice daily rhythm, were used. Distraction periods ranged from 12 to 32 days (mean ± SD: 21 ± 8 days; median: 25 days). Lengthening achieved ranged from 11 to 40 mm (mean ± SD: 20 ± 9 mm; median: 18 mm) or 6 to 30% (mean ± SD: 15 ± 8%; median: 13%) of the distracted bone’s initial length. All dogs had substantial improvement of their deformity and effective regenerate bone formation. Flexure contracture and wire and pin track inflammation were common complications during the convalescent period. Functional and cosmetic results (direct examination: mean ± SD: 130 ± 65 days; median: 123 days; telephone communication: mean ± SD: 351 ± 133 days; median: 324 days) were assessed as excellent in six, good in three and fair in two dogs and excellent in five, good in four and fair in one dog, respectively. The IMEX™ CESF system allowed precise deformity correction with minimal morbidity which was attributable to the system’s zero tolerance, zero motion properties.The IMEX™ Circular External Skeletal Fixator System was used to treat antebrachial deformities in nine dogs and to lengthen the mandible of one dog with prognathism. Functional results were assessed as excellent in six dogs, good in three dogs and fair in two dogs. Cosmetic results were assessed as excellent in five dogs, good in four dogs and fair in one dog.Presented at the 23rd Annual Conference of the Veterinary Orthopaedics Society, Telluride, CO, USA, March 5, 1996. University of Florida Journal Series #547.

Initial Clinical Experience with the IMEX™ Circular External Skeletal Fixation System

SummaryThe IMEX™ Circular External Skeletal Fixation (CESF) System was used to stabilize fractures (12 radius and ulna and five tibia and fibula) in 15 dogs and two cats and arthrodeses (two pancarpal, one talocrural and one pantarsal) in four dogs. The ages of the animals with fractures ranged from six months to nine years (mean ± SD: 2.7 ± 2.5 years; median: 2.0 years) and the body weights of dogs with fractures ranged from 5.4 kg to 48.6 kg (mean ± SD: 21.3 ± 12.6 kg; median: 22.7 kg). The ages of the dogs having arthrodeses ranged from eight months to two years (mean ± SD: 18±10 months; median: 18 months) and body weights of dogs with arthrodeses ranged from 19.0 kg to 29.1 kg (mean ± SD: 22.7 ± 4.7 kg; median: 21.4 kg). Ten fractures were open and four had been previously managed with another form of stabilization. Ten fractures were comminuted and all of the fractures involved the diaphysis; two extended to the distal metaphysis. An extensive open reduction was used on three, a limited open reduction on seven and a closed reduction on seven fractures. Arthrodeses were performed via a limited open approach, for debridement of the articular cartilage and implantation of a cancellous bone graft. Most animals placed substantial weight on the affected limb within a few days following the operations. Wire and pin track inflammation was the most common complication during the convalescent period and was often associated with a decrease in weight-bearing. Sixteen fractures achieved radiographic union (mean ± SD: 46 ± 13 days; median: 43 days) long-term function (direct examination: mean ± SD: 76 ± 38 days; median: 43 days; telephone communication: mean ± SD: 366 ± 247 days; median: 381 days) was assessed as excellent in 10 animals and good in seven. All of the arthrodeses achieved radiographic union (mean ± SD: 74 ± 31 days; median: 71 days). Longterm function (direct examination: mean ± SD: 185 ± 182 days; median: 102 days; telephone communication: mean ± SD: 485 ± 22 days; median: 590 days) was assessed as good in two dogs and fair in two dogs. Our results establish the utility of the IMEX™ CESF System for stabilizing fractures and performing arthrodeses in dogs and cats.The IMEX™ Circular External Fixator System was used to stabilize radius and ulna or tibia and fibula-fractures in 15 dogs and two cats and perform arthrodeses ir four dogs. Sixteen fractures and all four arthrodeses achieved radiographic union. Limb function was assessed as excellent in ten animals, good in nine animals and fair in two dogs.Presented at the 23rd Annual Conference of the Veterinary Orthopaedics Society, Telluride, CO, USA March 5, 1996 University of Florida Journal Series #547.