Distraction osteogenesis at the site of neutral wedge ostectomy for angular limb deformity in the hind limb in 2 young dogs.

Our objective was to report the use of distraction osteogenesis at the site of angular limb deformity correction using external skeletal fixation for treatment of 1 femoral and 1 tibial angular limb deformity in 2 large-breed puppies. Medical records were reviewed from 2 dogs (a 7-month-old intact male golden retriever and a 4-month-old intact female German shepherd mixed breed) diagnosed with angular limb deformities and truncation of a pelvic limb. Surgical treatment consisted of neutral wedge ostectomy and distraction osteogenesis at the site of bone deformity with an external skeletal fixator (ESF). The surgical technique and postoperative period of distraction osteogenesis were reviewed along with postoperative complications and clinical outcomes after complete bone healing was evident radiographically. Both dogs had adequate bone formation during distraction osteogenesis and the ESFs remained intact and structurally stable. At ESF removal, femoral length had increased 2.6 cm for Dog 1 and tibial length increased 3.88 cm for Dog 2, distal femoral valgus improved 16.3 degrees for Dog 1, and tibial procurvatum improved 19.5 degrees and distal tibial valgus improved 6.2 degrees for Dog 2. At the last follow-up examinations, 5 mo (Dog 1) and 3 mo (Dog 2) postoperatively, both dogs were ambulating without any visible lameness. Key clinical message: Acute angular correction and subsequent distraction osteogenesis at the site of bone deformity and corrective ostectomy using an ESF enabled successful treatment of femoral (Dog 1) and tibial (Dog 2) truncation and angulation in 2 large-breed puppies. Optimal deformity correction and lengthening were achieved through distraction osteogenesis at the site of neutral wedge ostectomy, minimizing soft tissue dissection and risk for potential complications that can occur with bifocal deformity correction (i.e., correction of the deformity at 1 osteotomy/ostectomy and correction of bone length at another, remote osteotomy).

Ostéogenèse par distraction au site d'ostectomie en coin neutre pour déformation angulaire du membre postérieur chez 2 jeunes chiens. Notre objectif était de rapporter l'utilisation de l'ostéogenèse par distraction au niveau du site de correction de la déformation angulaire du membre par fixation squelettique externe pour le traitement d'une déformation angulaire fémorale et d'une déformation angulaire tibiale chez 2 chiots de grande race. Les dossiers médicaux ont été examinés concernant 2 chiens (un golden retriever mâle intact âgé de 7 mois et une femelle berger allemand intacte de race mixte âgée de 4 mois) diagnostiqués avec des déformations angulaires des membres et une troncature d'un membre pelvien. Le traitement chirurgical consistait en une ostéogenèse en coin neutre et une ostéogenèse par distraction au niveau du site de déformation osseuse avec un fixateur squelettique externe (FSE). La technique chirurgicale et la période postopératoire d'ostéogenèse par distraction ont été examinées ainsi que les complications postopératoires et les résultats cliniques après une guérison osseuse complète évidente radiographiquement.Les deux chiens présentaient une formation osseuse adéquate pendant l'ostéogenèse par distraction et les FSE restaient intacts et structurellement stables. Lors du retrait de le FSE, la longueur fémorale avait augmenté de 2,6 cm pour le chien 1 et la longueur tibiale de 3,88 cm pour le chien 2, le valgus fémoral distal s'était amélioré de 16,3 degrés pour le chien 1, le procurvatum tibial s'était amélioré de 19,5 degrés et le valgus tibial distal s'était amélioré de 6,2 degrés pour le chien 2. Lors des derniers examens de suivi, 5 mois (chien 1) et 3 mois (chien 2) postopératoires, les deux chiens marchaient sans aucune boiterie visible.Message clinique clé :La correction angulaire aiguë et l'ostéogenèse de distraction ultérieure au site de déformation osseuse et l'ostectomie corrective à l'aide d'un FSE ont permis un traitement réussi de la troncature et de l'angulation fémorale (chien 1) et tibiale (chien 2) chez 2 chiots de grande race. La correction et l'allongement optimaux de la déformation ont été obtenus grâce à l'ostéogenèse par distraction au site de l'ostectomie en coin neutre, minimisant la dissection des tissus mous et le risque de complications potentielles pouvant survenir avec la correction de la déformation bifocale (c'est-à-dire la correction de la déformation à 1 ostéotomie/ostectomie et la correction de la longueur de l'os à une autre ostéotomie distante).(Traduit par Dr Serge Messier).

Distraction Osteogenesis in Two Wild Raptors.

Distraction osteogenesis was used in 2 wild raptor patients for the repair of tibiotarsal fractures. The first case was a hatching year female peregrine falcon (Falco peregrinus) admitted with an open oblique right distal tibiotarsal fracture. The fracture was surgically managed with the external skeletal fixator intramedullary pin tie-in technique (ESF-IM pin tie-in). Appropriate healing of the fracture site occurred with the ESF-IM pin tie-in. However, there was significant pelvic limb shortening of the affected leg, and the bird consequently developed pododermatitis on the contralateral foot. The second case was an adult female great horned owl (Bubo virginianus) that was admitted with a closed, partially healed, overriding right tibiotarsal fracture. Because of the advanced stage of this fracture, which presented with a fibrous callus, and the already apparent pelvic limb shortening, the ESF-IM pin tie-in was not used. Both patients were fitted with a circular external skeletal fixator (CESF), and distraction osteogenesis was performed until the length of the pelvic limb was deemed anatomically adequate. It is critical that rehabilitated raptors be released without any physical conditions that may reduce their ability to survive and reproduce in the wild. Pelvic limb shortening can potentially predispose a raptor patient to pododermatitis, even with fatal consequences, in both captive and wild environments. The orthopedic technique used here proved useful to repair the limb shortening in both raptor cases, and each bird fully recovered and was released.

Distraction Osteogenesis Correction of Mandibular Ramis Fracture Malunion in a Juvenile Mute Swan ( Cygnus olor ).

A juvenile mute swan (Cygnus olor) was presented with right lateral deviation of the mandible. Radiographs demonstrated a healed fracture of the right mandibular ramis, which had compromised osteogenesis. A corrective osteotomy was performed and an osteogenic distractor was inserted over the lateral aspect of the right mandible. Dental acrylic implants were fixed to the rhinotheca to correct rotational alignment. A pharyngostomy tube was placed to facilitate administration of nutrition and medication. Postoperative images confirmed correct alignment of the mandible in relation to the maxilla. Implants were removed and postoperative complications were not reported. This is the first report of an osteogenic distractor used to correct mandibular deviation in an avian species. Distraction osteogenesis should be considered as a valid surgical option in juvenile or adult avian patients with pathologic bone shortening.

Contralateral bone widening and transfer for limb sparing in a cat.

OBJECTIVE: To report on a novel surgical procedure to treat a long segmental tibial defect in a five-year-old 5 kg spayed female Main Coon cat using transverse distraction osteogenesis in the contralateral tibia to create a free autograft. METHODS: A long free bone segment was created from the cranial half of the normal tibia. A circular external fixator was constructed to give the segment 7 mm of cranial distraction. After 42 days the widened section of tibial bone was removed and transferred to the defect in the contralateral tibia. Locking plates were used to stabilize the graft and to protect the donor tibial sites. RESULTS: By 27 months, both tibias were healed, all implants had been removed, function was excellent, and the overall limb length was 90% of the normal side. CLINICAL RELEVANCE: Compared with longitudinal distraction osteogenesis in long bone defects, transverse distraction of a normal bone requires a significantly shorter distraction distance to produce a similar amount of bone. Thus, distraction time is reduced, with less likelihood of significant soft tissue damage. New bone may be more reliably regenerated in a normal limb due to better tissue health, and native bone may be more readily incorporated than allografts in compromised sites. Disadvantages include the increased morbidity, as well as the risk and expense associated with involvement of a normal limb.

Durations of bone consolidation and external fixation after distraction osteogenesis in dogs.

OBJECTIVE: To evaluate the influence of epidemiologic, surgical, and mechanical factors on the durations of bone consolidation and external fixation after distraction osteogenesis in dogs. STUDY DESIGN: Retrospective cohort study. SAMPLE POPULATION: Dogs (n = 115) that had corrective osteotomy with circular external fixation (CEF; n = 152) METHODS: Medical and radiographic records (1992-2012) of dogs that had corrective osteotomies were reviewed. Putative variables included age, weight, gender, and breed. Surgery date, delay before distraction, rate and duration of distraction, mechanical complications, and frame removal date were recorded. Radiographic data included bone operated, bone length, osteotomy site, bone and limb size at osteotomy site, distraction distance, and CEF frame size and stiffness. RESULTS: Mean ± SD bone consolidation period was 56 ± 33 days. Mean duration of external fixation was 77 ± 35 days. Twelve fixation failures occurred. Radii healed faster than tibiae (P < .001). Failure of fixation (P = .002) and stiff frames (P = .033) increased duration of bone consolidation. For the tibia, durations of bone consolidation and external fixation decreased with larger bone size relative to limb size (P = .004). For the radius, bone consolidation duration decreased as distraction amount increased (P = .03). CONCLUSION: Radii healed faster than tibiae. Wearing frames with low or moderate stiffness, the absence of mechanical complications, a larger distraction distance, and a larger bone size accelerated bone consolidation. Optimizing these factors should accelerate bone consolidation and reduce the duration of external fixation.

Correction of biapical radial deformities by use of bi-level hinged circular external fixation and distraction osteogenesis in 13 dogs.

OBJECTIVES: To describe clinical, radiographic, and computed tomographic (CT) assessment of biapical deformities of the radius in dogs and evaluate the effectiveness of their management by use of bilevel hinged circular external fixation frames. STUDY DESIGN: Prospective, non-randomized cohort study. ANIMALS: Dogs (N = 26: 13 with 14 limbs operated, 13 controls). METHODS: CT scans of the forelimbs were performed and CT-based polymer replicas prepared. Rotation within the elbow joint, varus of the proximal portion of the radius, radial torsion, valgus of the distal portion of the radius, procurvatum, and rotation within the carpal joint were measured on radiographs, on polymer replicas, and on CT scans. Bilevel hinged circular external fixation frames were assembled on polymer replicas and identical frames were placed on dogs. Torsion was corrected acutely and angulation was corrected progressively. Functional outcome was assessed subjectively. RESULTS: Buckling was present preoperatively in operated limbs. Mean (± SD) varus of the proximal portion of the radius was 36 ± 8°, valgus of the distal portion of the radius was 32 ± 5°, external radial torsion was 35 ± 6°, procurvatum was 41 ± 10°, and medial translation was 44 ± 11 mm. Treatment duration was 80 ± 24 days. Buckling was not observed after surgery. Lameness scores improved in all dogs (P < .001). CONCLUSIONS: The forelimbs of dogs with severe biapical radial deformities buckle and have increased radial head rotation and radial torsion. Biapical radial deformities can be managed with proximal and distal radial osteotomies and bilevel hinged circular external fixation.

Distraction-stabilisation of two adjacent intervertebral spaces in a Dalmatian dog with caudal cervical spondylomyelopathy.

A 4-year-old, 40-kg, male, entire Dalmatian was presented for evaluation of chronic neck pain and pelvic limb ataxia. Myelography revealed ventrodorsal (hourglass) extradural compression over the intervertebral space between the 5th and 6th cervical vertebra and ventral extradural compression between the 6th and 7th cervical vertebra. Cranial compression disappeared and caudal compression markedly diminished after performing cervical traction. MRI scan confirmed protrusion of intervertebral discs and spinal cord compression in previously mentioned intervertebral spaces. Surgical distraction-stabilization of both intervertebral spaces was performed using threaded pins and polymethylmethacrylate. The convalescence from surgery was uneventful and the dog was walking without any signs of paresis until 5 months after surgery when radiography revealed implants loosening. The dog recovered fully of the implant removal and remained asymptomatic for more than 30 months.

Bifocal femoral deformity correction and lengthening using a circular fixator construct in a dog.

A 7 mo old male rottweiler was evaluated for a right hind limb lameness caused by malunion of a Salter-Harris type II fracture. Radiographs and computed tomography (CT) revealed that the right distal femur had valgus, procurvatum, external rotation, and was 35% (70 mm) shorter than the contralateral femur. Distal femoral wedge ostectomies were performed to acutely correct the angular and rotational deformities. Lengthening of the femur was accomplished by distraction osteogenesis performed over 53 days at a second, proximal diaphyseal osteotomy using a circular fixator construct. This bifocal approach yielded approximately 30 mm of femoral lengthening and a confluent column of regenerate bone that bridged the distraction gap. When evaluated 14 mo after surgery, the dog held the right hip, stifle, and hock in a slightly extended posture when standing and had a subtle asymmetric hind limb gait. The stride of the right hind limb was slightly shortened with compensatory circumduction of the left hind limb during the swing phase of the stride.

External fixators and minimally invasive osteosynthesis in small animal veterinary medicine.

Modern external skeletal fixation (ESF) is a very versatile system that is well suited to the ideals of minimally invasive osteosynthesis (MIO). It offers variable-angle, locked fixation that can be applied with minimal to no disruption of the fracture zone. Technological advances in ESF have fostered the ability to use more simple frame applications than in previous generations. Even when rigid bilateral or multiplanar frames are required, timely staged-disassembly is easy to perform and allows for a gradual shift of loading from the frame to the healing bony column. Hybrid ESF is ideally suited for the MIO treatment of many juxta-articular fractures and osteotomies. Adherence to the principles of ESF and postoperative care is essential to overcome the various disadvantages that are inherent to ESF.

Use of hinged circular fixator constructs for the correction of crural deformities in three dogs.

BACKGROUND: Hinged circular external skeletal fixator constructs are used to perform sequential correction of angular limb deformities, often with resultant limb segment lengthening, via distraction osteogenesis. Although there are several reports describing the use of these constructs for correction of antebrachial deformities in dogs, there is little information regarding their use on other limb segments. This report describes the use of hinged circular fixator constructs for the correction of acquired crural deformities in three skeletally immature dogs. CASE REPORTS: Two dogs had purely frontal plane deformities (one valgus, one varus) and the third dog had frontal (valgus) and sagittal (recurvatum) components to its deformity. At the time of long-term evaluation, frontal plane angulation relative to the contralateral limb improved from 40° to 22° of valgus, 30° to 5° of valgus, and 20° to 1° of varus in the three individual dogs. Tibial length discrepancies of 12% and 22% that were initially present in two dogs were improved to 6% and 10%, respectively, of the contralateral tibial length at the time of final evaluation; both dogs had compensatory growth of the ipsilateral femur and all dogs had an excellent functional outcome. CONCLUSION: These cases illustrate the value of using hinged circular fixator constructs for correction of crural angular deformities, particularly when length discrepancies of the tibia are present.

Femoral angular correction and lengthening in a large-breed puppy using a dynamic unilateral external fixator.

OBJECTIVE: To report treatment of a large-breed puppy with combined distal femoral valgus and length deficit caused by partial distal physeal closure. STUDY DESIGN: Clinical report. ANIMALS: Bernese Mountain Dog (4.5-month-old male). METHODS: The puppy was admitted for evaluation of a progressive severe left pelvic limb lameness (grade 3/4) of 6-week duration. Distal femoral valgus and severe length deficit deformity were treated by acute angular correction using a closing wedge ostectomy and progressive rapid-rate callus distraction using a dynamic, telescoping unilateral External Skeletal Fixator (ESF) designed for people. After acute angular correction and a 3-day latency period, a mean linear distraction rate of 3 mm/day was maintained for 3 weeks. The dynamic ESF (dESF) was removed at 4 weeks, after a 1-week consolidation phase. RESULTS: The dESF was stable and functional during distraction and bone healing. Distal femoral valgus conformation improved 50° (from 41° to 91°) and femoral length increased 42 mm at dESF removal (from 158 mm to 200 mm; 27%). After cessation of bone growth, no valgus and minimal (6%) length deficit were detected. At 4, 5, 6, 12, and 24 months after surgery, the dog was walking, trotting, and galloping normally. CONCLUSION: Acute angular correction and progressive rapid-rate callus distraction using a unilateral dESF allowed satisfactory treatment of combined distal femoral valgus and length deficit in a large-breed puppy.

Cervical spine locking plate fixation for treatment of cervical spondylotic myelopathy in large breed dogs.

OBJECTIVE: To describe indirect decompression by means of cervical spine locking plate (CSLP) fixation with vertebral distraction, discectomy, and cancellous block bone grafting in large breed dogs with single caudal cervical dynamic spondylotic lesions diagnosed by myelography with linear traction to the cervical spine, and contrast-enhanced computed tomography. STUDY DESIGN: Prospective clinical study. ANIMALS: Dogs (n=12) with caudal cervical spondylotic myelopathy because of a single dynamic, traction-responsive lesion. METHODS: Single, traction-responsive, caudal cervical spondylotic lesions were treated by vertebral distraction, discectomy, cancellous block bone grafting, and CSLP fixation. Follow-up was obtained by sequential recheck examination by the author or referring veterinarian or by telephone inquiries. RESULTS: Ten dogs had neurologic improvement after surgery. Indirect decompression by maintained distraction with cancellous block grafting and CSLP fixation was readily accomplished with less risk of blood loss or iatrogenic spinal cord injury than that associated with direct (ventral) decompression. There were no complications of graft intrusion, extrusion or subsidence, implant loosening, foraminal impingement, or end-plate failure. Two dogs that had satisfactory short-term recoveries developed clinical signs associated with adjacent segment disease and were euthanatized. At long-term follow-up, 8 dogs had satisfactory function, either a normal gait or one with slight to moderate proprioceptive deficits. CONCLUSIONS: CSLP fixation with cancellous block interbody grafting is an effective and perhaps safer method of treating single-level, traction-responsive cervical spondylosis in large breed dogs. CLINICAL RELEVANCE: CSLP fixation with interbody bone grafting is a viable alternative to other techniques for treatment of single-level, traction-responsive cervical spondylosis.

Experimental study of bone lengthening in dogs by means of backscattered scanning electron microscopy.

OBJECTIVE: To describe the morphology of calcified tissues involved in distraction osteogenesis (DO) by means of backscattered scanning electron microscopy (BS-SEM). STUDY DESIGN: Experimental study. ANIMALS: Adult female Beagle dogs (n=12). METHODS: Non-simultaneous and bilateral transverse mid-diaphyseal osteotomies performed in tibiae were stabilized and distracted by a Type Ia external skeletal fixation device. After a latency period of 5 days, distraction was applied at a rate of 0.5 mm every 12 hours for 10 days. Then, the external fixator was maintained in a static mode during the consolidation period until bone healing or euthanasia at 1, 2, 3, 4, 6, 8, 10, 12, 14, and 18 weeks after operations, whichever came first. Distracted regions were isolated and their structure was examined by BS-SEM. RESULTS: Calcified chondroid tissue was prominent during distraction and calcified cartilaginous tissue during consolidation; both tissues were successively replaced by woven, lamellar, and osteonal bone. CONCLUSIONS: In osteotomized tibia, chondroid tissue is the main component of the mineralization front during distraction, calcified cartilaginous tissue during consolidation, and then both tissues are replaced by woven, lamellar, and osteonal bone. The ossification mechanism of distraction callus is transchondroidal. CLINICAL RELEVANCE: BS-SEM is an effective technique for studying progression of bone healing during DO. The presence of chondroid tissue during DO explains why callus mineralization occurs more rapidly during distraction than during static stabilization.

Locking compression plate osteosynthesis of complicated mandibular fractures in six horses.

Complicated mandibular fractures were recognised in one foal, one pony and four horses. The foal was two months old while the adult animals ranged in age from 12 to 24 years. Three horses had a unilateral horizontal ramus fracture. Two fractures were open and one was closed. Comminution was present in one of these patients while the other two horses had marked displacement of the fragments. Two suffered from comminuted fractures of the horizontal and vertical ramus of the mandible. One of these patients had open and infected fractures. One foal had a bilateral horizontal ramus fracture with marked periosteal 'new bone' formation and malalignement which required corrective osteotomy. Each horse underwent locking compression plate (LCP) osteosynthesis consisting of open fracture reduction and application of one to three 4.5/5.0 mm LCP at the ventral, lateral or caudal aspect of the mandible under fluoroscopic control. Two 3.5 mm LCP were used in the foal. Plate fixation was supported by application of a cerclage wire construct between the incisor and premolar teeth in most patients. Complete fracture healing, with an excellent functional and cosmetic outcome, was achieved in all of the patients. Complications encountered included seroma formation, screw and wire breakage, as well as implant and apical tooth root infections. The LCP was removed after fracture healing had occurred in four patients.

Limb lengthening in three dogs using distraction rates without a latency period. Radius/ulna, tibia, femur.

OBJECTIVE: To report three clinical cases suffering from limb shortening secondary to monostotic physeal closure, in which distraction osteogenesis had been performed without a latency period and with high distraction rates. METHODS: Three dogs had limb lengthening performed, using an Ilizarov ring fixator in two dogs and a linear dynamic fixator in the other dog. Bone lengthening achieved for a radius/ulna was 27 mm at 2 mm per day , a tibia was 78 mm at 3 mm per day, and a femur of 45 mm was 3 mm per day . RESULTS: Complications related to pin loosening occurred in each case, thus requiring surgical corrective procedures, but these did not affect the final outcome. Lateral bowing of the bar and bone and some musculo-cutendinous contracture occurred in the femur. Fixation frames were on for 12 weeks in Case 1, eight weeks in Case 2 and nine weeks in Case 3. All three of the cases had a good functional outcome. DISCUSSION: The faster rates of lengthening were not associated with any long-term deleterious soft tissue complications, but they were associated with pin loosening and bending of the bar. In each case there was excellent osteogenesis. CONCLUSIONS: From the results achieved in these three cases it can be concluded that a latency period prior to distraction osteogenesis may not be necessary. Also, distraction rates up to 3 mm per day can be used to shorten the time needed to achieve lengthening; however further studies are needed to investigate the high level of complications.

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.

Bone transport osteogenesis for reconstruction of a bone defect in the tibiotarsus of a yellow-naped Amazon parrot (Amazona ochrocephala auropalliata).

A yellow-naped Amazon parrot (Amazona ochrocephala auropalliata) was presented 5 months after a traumatic fracture of its left tibiotarsus. Fixation of the simple, closed, mid-diaphyseal fracture was originally with an intramedullary pin and external coaptation with a modified Robert-Jones bandage. During the subsequent 5 months, the bone became osteopenic, and the middle third of the tibiotarsus exhibited probable avascular necrosis. After various fixation attempts failed, the parrot was fitted with a ring fixator device, and bone transport osteogenesis was attempted. Within 7 weeks, the left tibiotarsus had regrown to full length, but the docking site at the proximal fracture line had not healed. After 2 more surgeries to debride bone ends to stimulate healing, the leg in this parrot became functional. This is the first reported clinical use of bone transport osteogenesis in a pet bird. Materials and techniques were applied successfully to this parrot, which suggests that bone transport osteogenesis deserves further study for the repair of large bone defects in birds.

Mandibular osteodistraction for correction of deep bite class II malocclusion in a horse.

OBJECTIVE: To describe a technique for, and outcome after, mandibular osteodistraction in the horse. STUDY DESIGN: Clinical report. ANIMALS: Warmblood horse. METHODS: A half ring external fixator was applied on both sides of an osteotomy site performed on the mandible of a colt. A bite plate was placed on the upper incisors creating occlusion between lower and upper jaw. After a 5-day latency period, distraction was applied (1 mm/day) until the overjet was judged normal. RESULTS: Mandibular elongation and correction of brachygnathia was obtained without major complications. Six months after the procedure the overjet reduction was considered stable. CONCLUSIONS: Mandibular osteodistraction can be considered for treatment of severe brachygnathia in yearlings. CLINICAL RELEVANCE: Distraction osteogenesis has the advantage of progressive elongation of the mandible, allowing concurrent bone remodeling and soft tissue adaptation. Severe mandibular incisor malocclusion in horses outside the maximal growth phase can be corrected using this technique.

Transverse ulnar bone transport osteogenesis: a new technique for limb salvage for the treatment of distal radial osteosarcoma in dogs.

OBJECTIVE: To develop instrumentation and a technique for transverse ulnar bone transport osteogenesis in dogs. STUDY DESIGN: Cadaveric study and in vivo validation (1 dog). SAMPLE POPULATION: Paired cadaveric antebrachii (n=10 dogs) and 1 live dog. METHODS: Circular fixator constructs were applied and fitted with reeling or linear motors designed to transport an ulnar segment transversely into a defect created by excising the distal 50% of the ipsilateral radius. A longitudinal osteotomy of the adjacent ulna was created and the segment was transported across the radial defect. Pre- and post-distraction CT scans were used to compare the efficacy of each construct. The procedure was performed unilaterally in a live dog using the reeling motor (RM) construct. RESULTS: Both constructs effectively transported the ulnar segment into the defect. Subjectively, the RMs were easier to apply and operate. No significant differences were observed in the objective measures of efficacy between the 2 construct types. The live dog produced viable regenerate bone after transverse ulnar bone transport. CONCLUSIONS: Transverse ulnar bone transport should be considered a potential method for limb salvage in dogs with osteosarcoma (OSA) of the distal radius. The RMs were effective and clinically applicable. CLINICAL RELEVANCE: Transverse ulnar bone transport osteogenesis affords the benefits of longitudinal radial bone transport osteogenesis, allowing resolution of large longitudinal radial defects in a substantially less time as a result of shortening the transport distance. This would be beneficial when treating conditions such as OSA where minimizing convalescence and maximizing quality of life is a priority.

Intramedullary pinning of metacarpal and metatarsal fractures in cats using a simple distraction technique.

OBJECTIVE: To describe a simple technique of intramedullary (IM) pinning for open reduction and internal fixation of metacarpal and metatarsal fractures in cats and evaluate outcome. STUDY DESIGN: Retrospective study. ANIMALS: Cats (n=17). METHODS: Medical records of cats with metacarpal and metatarsal fractures treated by a specific IM pinning method with Kirschner wires were reviewed. Types of fractures and number of pins used were recorded. Pre- and postoperative radiographs were evaluated. Outcome was assessed based on clinical examination, evaluation of radiographs, and owner questionnaire. RESULTS: Seventeen questionnaires were evaluated. Thirteen cats had a final recheck and radiographic assessment. Eight cats were lost to follow-up. Sixteen owners (94%) reported no obvious change in their cat's gait after treatment. One owner reported excellent function in her cat despite a slightly abnormal gait because of bent implants. CONCLUSIONS: IM pinning after distraction of bone fragments is a reliable technique for treatment of metacarpal and metatarsal fractures in cats. Complications associated with fracture healing may or may not be associated with lameness. CLINICAL RELEVANCE: IM pinning used in conjunction with appropriate bandaging for 4 weeks yields excellent functional outcome for treatment of metacarpal and metatarsal fractures in cats. Metacarpo- and metatarsophalangeal joint damage is prevented using this technique.