External Skeletal Fixation Research Articles

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.

Dorso-medial antebrachiocarpal luxation with radio-ulna luxation in a domestic shorthair

An 8-year-old domestic shorthair was admitted with non-weight bearing left forelimb lameness. Examination and radiographs revealed dorso-medial ante-brachiocarpal luxation with palmar luxation of the distal radio-ulnar joint. Primary repair was performed and stabilised using an arthrodesis wire and type Ia Kirschner-Ehmer (K-E) external skeletal fixator (ESF). The cat regained excellent pain-free limb function by 14 weeks with only minor reduction in range of movement. This is the first case report of a cat with distal radio-ulnar joint luxation associated with ante-brachiocarpal luxation. Primary repair of carpal luxation in the cat should be considered before arthrodesis.

Biomechanical Analysis of Unilateral External Skeletal Fixators Combined with IM‐Pin and Without IM‐Pin Using Finite‐Element Method

To determine if a unilateral external skeletal fixator (ESF) with a carbon fiber connecting rod (IMEX SK) without an intramedullary (IM)-pin is mechanically comparable with a unilateral ESF with a stainless-steel connecting rod (IMEX KE) with an IM-pin. Finite-element method (FEM)-computer simulation. FEM models were validated by comparison against data from mechanical testing. Three-dimensional FEM models of a femur with a mid-diaphyseal fracture with a 20 mm gap were developed with 4 unilateral external skeletal fixator devices (6-pin KE, 6-pin KE IM-pin, 6-pin SK, and 6-pin SK IM-pin). A 300 N load was applied to the femur at the proximal end in a direction of theta = 10 degrees distally and phi = 10 degrees laterally cranially. Relative displacements in x-, y- and z-directions at the gap were obtained and the overall stiffness was calculated as 300 N/total displacement. Load transfer at the pin-bone interface (PBI) was assessed by determining the von Mises stress maxima at the PBI-related nodes. The 6-pin SK had superior mechanical performance compared with the 6-pin KE by exhibiting smaller displacements in all directions and higher stiffness. Compared with the 6-pin KE IM-pin, the 6-pin SK (without IM-pin) was superior in craniocaudal and lateromedial displacements, but inferior in axial displacements, overall stiffness and von Mises stress maxima. The 6-pin SK IM-pin was superior to the 6-pin KE IM-pin based on smaller displacements and higher stiffness. Although the SK device had superior mechanical performance compared with a KE device in a unilateral configuration, the addition of an IM-pin continues to be a powerful method of enhancing mechanical performance of either IMEX SK or IMEX KE unilateral constructs in clinical cases. Based on the results of this FEM study we recommend the use of the "tied-in" IM-pin with the ESF clinically when striving for high rigidity. In less challenging situations, a unilateral SK ESF without IM-pin might provide sufficient rigidity for a successful fracture repair.

Clinical application of intraoperative skeletal traction in the dog

The purpose of this clinical study was to evaluate the technical feasibility of a method for pre-operative and intra-operative traction for reduction of fractures of the appendicular skeleton. Traction was used in 24 diaphyseal fractures in 21 dogs. For each dog, the data pertaining to signalment, limb circumference, fracture type, interval between fracture and surgery, and the traction modalities were recorded. In patients with a latency between trauma and surgery of less than three days, the duration of traction required to realign the bone segments was shorter than that required for older fractures (P = 0.02). Intraoperative malalignments were corrected by manoeuvres performed with the traction stand. Once realigned, fracture segments were kept stable for prolonged periods, without the need for a surgical assistant. Postoperative radiographs were evaluated for fracture reduction and axial alignment. Postoperative alignment was judged excellent in 21 fractures and good in three fractures. Fractures were stabilized using external skeletal fixation (n = 10), plates (n = 11) or locked nails (n = 3), depending on the fracture type. The use of the technique was straight-forward and easily applied in a surgical setting. However, its use requires careful application because of the potential for iatrogenic tissue damage.

Penetrating missile injuries in the Gulf war 1991

During the recent Gulf war 63 patients with penetrating missile injuries (including 29 Iraqi prisoners of war) underwent operation in a British Army Field Hospital. Their injuries and initial operative management are reported. Fifty-one casualties (81 per cent) suffered an average of nine wounds (range 1-45) due to fragmentation weapons, and 12 casualties sustained bullet wounds. All wounds were explored following the established principles of war surgery. The extremities were involved in 48 patients (76 per cent). Eight compound long bone fractures were managed with external skeletal fixators applied at the time of initial operation. Laparotomy was performed on seven patients, one of whom died. The average duration of operation was 77 min for shrapnel wounds and 85 min for bullet wounds.

In vivo axial dynamization of canine tibial fractures using the Securos external skeletal fixation system

Bilateral transverse mid-shaft tibial osteotomies, with a 4-mm gap, were performed in purpose-bred research dogs and stabilized using a Securos Type 2 external skeletal fixotor (ESF). Full (100%) axial dynamization of one randomly selected ESF in each dog was performed at 31 days postoperatively. Caudo-cranial radiographs were obtained at weekly intervals, which were qualitatively and quantitatively evaluated (densitometry and ImageJ analysis). The dogs were euthanatized 13 weeks postoperatively, at which time dual energy x-ray absorptiometry (DEXA), peripheral quantitative computed tomography (pQCT), mechanical testing in torsion, and qualitative histological analysis were performed. A two-tailed paired Student's t-test was performed for statistical analysis of all parameters of interest, with significance set at p < 0.05. Three of five dynamized bones bridged quicker, and four of five dynamized bones appeared to have greater callus formation, however, statistically significant differences could not be definitively determined. Statistically significant differences were not found with densitometry (any time frame), DEXA, pQCT, torsional stiffness or maximum torque. Despite the lack of statistically relevant data, trends were observed with larger callus size and density in the dynamized tibiae. The dynamized tibiae appeared to fracture more consistently outside of the area of the healing callus as compared to the control tibiae. Histological evaluation showed greater remodelling in four of five control limbs when compared to the dynamized limb. Dynamization at 31 days post-operatively may delay bone remodelling, despite a trend towards a larger callus size. The results of this study failed to show a definitive role for early full axial dynamization.

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.

Repair of a Tibiotarsal Varus Malunion in a Bald Eagle (Haliaeetus leucocephalus) With a Type lA Hybrid External Skeletal Fixator

Fracture malunion in a raptor can compromise muscle and tendon function and adversely affect normal activities that are essential for survival in the wild. Malunion can be acutely corrected by osteotomy techniques followed by bony fixation that provides sufficient stability to allow unimpeded healing with minimal soft-tissue injury. We describe an adult bald eagle (Haliaeetus leucocephalus) that was presented after being found in poor body condition and unable to fly. Radiographs revealed a healing middiaphyseal fracture and a recent distal fracture of the right ulna and a right distal tibiotarsal varus malunion. The ulnar fractures healed without medical intervention; however, surgical correction of the malunion was required. An open-wedge corrective osteotomy was performed and a Type lA hybrid external skeletal fixator was used to stabilize the osteotomy. The osteotomy healed and the eagle was returned successfully to the wild.

Combined external skeletal fixation instrumentation with locked intramedullary nailing for tibia lengthening

To shorten the time of external skeletal fixation on legs, and enhance quality of limb lengthening, avoid complications of shortening, bending, twisting and etc. Insert pin transcortical to attack external skeletal fixation simultaneously, put un-reaming locked intramedullary nail (do not insert distal locked screw) into endosteum of lengthening bone. After the legs achieved predetermined length, insert distal locked screw and then remove external skeletal fixation, locked intramedullary nail, then maintain consolidation of rehabilitation. The group lengthened legs for 412 cases. The range of lengthening was 3 to 18 cm. Mean length was 7.6 cm. The mean time for needed external skeletal fixation was 20 d/cm. The mean time of osteogenesis was 56 d/cm. For complications, there were 3 tibias ununion cases and 1 varus ankle. All cases were treated undergoing twice. The method reduces the time for needed external skeletal fixation visibly, enhances the quality of limb lengthening remarkably, prevents complications of shortening new bone, deformity, bending and re-fracture which do not effect the healing time. This is a new choice of limb lengthening.

Prevalence of pin site infection among patients with external skeletal fixation

Prevalence of pin site infection among patients with external skeletal fixation

Treating pedal shortening in a dog by metatarsal distraction osteogenesis

A five-month-old, male German shepherd dog was presented with a left hindlimb deformity. Wearing a cast for a prolonged period to treat left metatarsal fractures at eight weeks of age had resulted in physeal closure of the calcaneus, metatarsals and phalanges. Hyperextension of the phalanges and ulceration of the plantar skin proximal to the main tarsal pad were seen. The left foot was 40 mm shorter than the right. At seven months of age, a modified circular external skeletal fixator (CESF) was used to perform distraction osteogenesis of the metatarsal bones for 28 days. The CESF apparatus was removed after eight weeks when there was radiographic consolidation of regenerate bone. At follow-up evaluations four and 12 months after surgery, the phalangeal hyperextension and plantar skin ulceration had resolved. No lameness was detected.

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.

Accuracy of Computerized Tomographic Evaluation of Canine Radio‐Ulnar Incongruence In Vitro

To evaluate the accuracy of linear measurements obtained from computer tomography (CT) images of staged radio-ulnar incongruence in a canine cadaver forelimb model. CT evaluation of induced progressive radio-ulnar incongruence in canine cadaveric forelimbs. Eight cadaveric canine left forelimbs. A type 2 external skeletal fixator (ESF) with linear motors was attached to the radius in 8 cadaveric left canine forelimbs. Contiguous incremental and helical CT images of the proximal radio-ulnar articulation were acquired in the transverse, sagittal and dorsal planes. The radius was shortened by 1, 2, and 4 mm increments and scanning protocols were repeated at each increment. Digital caliper and CT image analysis measured the progressive change in distance between 2 marking spheres and the epiphyseal bone surfaces of the radio-ulnar articulation. Statistical analysis of measurements from incremental and helical CT acquisitions, and direct and reformatted images were compared with inter-sphere distance using Pearson product moment correlation coefficients. The reformatted incremental acquisition series at the mid-coronoid in the oblique plane had the highest correlation coefficient (r-value) at 0.908. The mid-coronoid in the dorsal plane had the second highest r-value (0.856). The coronoid incisure in the sagittal plane had an r-value of 0.826. The reformatted incremental acquisition series at the coronoid incisure in the oblique plane had the lowest r-value, 0.592. Measurement of radioulnar incongruence may be best performed using reformatted incremental acquisition CT in the mid-coronoid region in an oblique plane. Use of the technique reported in this study may enable determination of the association, if any, between radioulnar incongruence and developmental diseases of the canine elbow.

Practical guide to linear external skeletal fixation in small animals

EXTERNAL skeletal fixation is a very adaptable technique that can be used to stabilise a wide variety of fractures. A basic frame can be applied using relatively inexpensive equipment, and...

New concept in external fixation

A new concept in external skeletal fixation is presented. A 3D unilateral system developed by Mitkovic has widely been investigated biomechanically in AO institute in Davos (Switzerland). Consists of three components only providing extremely simple application and dynamic fixation of bones and different joints. This simple external fixator functions as an accurate reduction device at the same time, minimizing need for fluoroscopy. Clinically this system has been applied to mere then 13 thousand patients in 43 clinics. This paper presents the results of its application for treatment of open fractures, war wounds with fractures and for comminuted and intraarticular closed fractures in the series of 597 patients. Overall average time for union time was 3.2 months. Overall success of fracture healing was 96.8% including open and closed fractures. Our study suggests that the use of this 3D unilateral system is suitable for routine use.

Clinical Outcome of Surgical Treatment of Distal Radius Fracture Using External Skeletal Fixation

Clinical Outcome of Surgical Treatment of Distal Radius Fracture Using External Skeletal Fixation

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

To identify the most common sites of and possible predisposing factors for nonunions in cats with fractures of the appendicular skeleton. Retrospective study. 344 cats treated for fractures between 1998 and 2002, 18 of which developed nonunions. Information collected from the medical records included signalment; type of trauma; fracture location, orientation, and type; degrees of displacement and comminution; treatment; and outcome. 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. 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.

External skeletal fixation of the tibial shaft fractures

To present the possibility of a succesfful use of external skelatal fixation in treating the open and closed tibial shaft fractures with Mitković's external fixator. External fixation was used in 115 patients with 118 fresh tibial shaft fractures, 82 males (71.3%) and 33 females (28.7%), average age 43.92 years (16-84). Open tibial shaft fractures were present in 37 (31.36%). All the fractures were treated with Mitković's external fixator type M 20. The results of external fixation were excellent or good in 94.07% of the cases, and bad in 5.08%. Pin tract infection appeared in 7 (5.93%) patients. In only 3 cases an external fixator was removed and treatment continued with the functional braces. Nonunion occurred in 6 (5.08%) patients, of which 4 were with open fractures (2 Gustilo type IIIB, 1 Gustilo type IIIA, 1 Gustilo type II) and 2 with the segment fractures. Compartment syndrome was observed in 1 (0.85%) patient with closed fracture. Malunion was found in 2 (1.69%) patients. External fixation of tibial shaft fractures is a simple and effective method to enable the safe healing of fractures, early mobilization of the patients, early weight-bearing, as well as early rehabilitation. Fixation of tibial shaft fractures was unilateral with convergent pins orientation, and there was also a possibility of compression and distraction.

The feline humerus

The humeri of eleven feline cadavers were dissected and safe anatomical areas for placing external skeletal fixator pins were determined. Relevant measurements taken of the humeral condyle enabled a determination of a safe pin diameter range of 1.5 to 2.2 mm for transcondylar pins. Further anatomical measurements allowed recommendations to be made to angle pins in the distal humerus in a distolateral proximomedial direction so that the ESF pin penetrates the for cortex at least 20 mm proximal to the medial epicondyle in order to avoid pin penetration of the supracondylar foramen. Cross sections taken of the distal humerus revealed that passage of an IM pin into the medial aspect of the humeral condyle was possible in less than half the cases.

Imobilização de fraturas femorais em gatos usando pino intramedular conectado ou não ao fixador esquelético externo

O trabalho teve por objetivo comparar a consolidação óssea e a função do membro, em 18 gatos com fraturas transversas femorais tratadas com pino intramedular e fixador esquelético externo tipo Ia (grupo I, n=9) ou com pino intramedular associado ao fixador externo em uma configuração "tie-in" (grupo II, n=9). Independente da configuração utilizada, após a remoção dos implantes, todos os animais apresentaram função normal do membro operado. Não houve diferença entre os grupos em relação à densidade mineral óssea do calo externo mensurada pela densitometria óptica por imagens radiográficas. O tempo para consolidação foi significativamente maior para as fraturas tratadas com pino intramedular e fixador tipo Ia. As fraturas que receberam a configuração "tie-in" tiveram menos proliferação de calo ósseo.