Repair of femoral fractures in calves via external skeletal fixator with intramedullary pin tie-in.

OBJECTIVE: To describe the success rate and associated complications of external skeletal fixator/intramedullary pin tie-in for calf femoral fracture fixation. STUDY DESIGN: Clinical retrospective. ANIMALS: Ten calves, less than 30 days old, with diaphyseal/metaphyseal femoral fractures. METHODS: Medical records were reviewed from the University of Wisconsin from 2000 to 2020. Fractures were repaired using open reduction and fixation. An intramedullary Steinman pin was placed, exiting near the greater trochanter, and utilized for fracture reduction. Bicortical transfixation pins were placed distal and proximal to the fracture site. Poly(methyl methacrylate) (PMMA)-filled tubing connected the transfixation pins and proximal intramedullary pin, creating a Type 1a external skeletal fixator (ESF) tie-in. Follow up was obtained via medical records and phone interviews. RESULTS: Short-term survival rate was 7/10 (70%). Postanesthetic death occurred once. Postoperative complications occurred in all remaining cases. The most common findings were transfixation pin tract lucency and lameness (6/9 cases), implant dysfunction (5/9 cases), and infection (4/9 cases). Three of five cases with long-term follow up survived; all went on to productive careers. CONCLUSION: Although patients were prone to postoperative complications, short-term survival was comparable to previous reports. CLINICAL SIGNIFICANCE: The external skeletal fixator/intramedullary (ESF/IM) pin tie-in is less expensive and offers comparable success rates to other methods, providing a lower cost option for calf femoral fracture repair.

Management of Feline Femoral, Tibial and Humeral Fractures Using a 3.5 mm Titanium Interlocking Nail.

OBJECTIVE: Our objectives were to report complications associated with stabilization of long-bone fractures in cats using a 3.5-mm titanium interlocking nail and to examine the influences of signalment, fracture type and fixation evaluations on the occurrence of complications. STUDY DESIGN: Retrospective clinical study. MATERIAL AND METHODS: Medical and radiographic records of cats with long-bone fractures treated with an interlocking nail were reviewed. Data included age, sex, weight, cause of the fracture, fractured bone(s) and fracture type. Complications were classified as minor and major complications. Fisher's exact tests and logistic regression analysis were used to test whether certain variables of signalment and interlocking nail configuration had an effect on the occurrence of complications. RESULTS: Sixty-seven fractures of 67 cats were examined in this study. Forty-eight femora, sixteen tibiae and three humeri were included. Complications occurred in 11/67 fractures. Major complications occurred in 8/67 fractures and included screw breakage (n = 3), nail breakage (n = 2), nail bending (n = 1), screw loosening (n = 1), non-union (n = 1). Statistical analysis showed a significant difference between fracture types and the occurrence of major complications (p = 0.02). CONCLUSION: In conclusion, use of this commercially available standard 3.5-mm titanium interlocking nail for stabilization of comminuted and oblique humeral, femoral and tibial fractures in cats is feasible.

Limb Gait Score of Femur Fracture Fixated by Intramedullary Pinning in Dogs.

Animal posture, limb gait, and body weight-bearing in dogs can be evaluated by limb gait score. In this study, nine adult male dogs of local breed were used to induce a complete transverse femoral mid-shaft fracture fixed internally by intramedullary pining under general anesthesia with the aseptic technique and followed for 60 days postoperative. The data were analyzed, including five degrees that indicate the correlation among animals' posture, limbs, and body weight tolerance per day. The results demonstrated that in grade 5, the animals completely hold the affected limb during standing position 1st-3rd day postoperative. From the 4th-10th day postoperative, in grade 4, the animals supported the body weight on the affected limb in the standing position and hold it during waking. In grade 3, from 11th-21th day postoperative, the operated animals supported body weight on the affected limb in slow waking and hold it in speed waking and running. From the 22nd-28th day postoperative, in grade 2, the animals used the limb in speed walking, from the 29th-35th day postoperative. In grade1, the animals could use the limb in running from the 36th-2nd day postoperative. In grade 0, the animals used the limb normally in walking, running, and jumping until the end of experimental periods (60th day postoperative). The results indicated that limb gait scores in dogs can be used for the evaluation of the relationships among animals' posture, limb gait, and body-weight bearing per day during bone regeneration processing of femur fracture fixed by intramedullary pining.

Correção de fratura Salter-Harris tipo I em porquinho-da-índia (Cavia porcellus) - relato de caso / [Correction of Salter-Harris type 1 fracture in guinea pig (Cavia porcellus) - case report]

Um filhote de porquinho-da-índia (Cavia porcellus) foi recebido para atendimento após histórico de ataque por cão. Na avaliação física, observou-se edema, dor e crepitação em membro pélvico direito, sugestivo de fratura. Na avaliação radiográfica, confirmou-se fratura Salter-Harris tipo I em epífise distal da tíbia. A resolução cirúrgica escolhida foi a associação de pino transarticular e coaptação externa com tala de Altman. O paciente teve acompanhamento radiográfico semanal e obteve alta médica no 35o dia de pós-cirúrgico, quando se observou consolidação com completo remodelamento ósseo.(AU)

A guinea pig (Cavia porcellus) cub presented edema, pain, and crepitus in the right pelvic limb after being attacked by a dog. Radiographic examination revealed Salter-Harris type 1 fracture on the distal region of the tibia. The surgery technique to correct the fracture involved an association of transarticular pinning and external coaptation with Altman splint. After surgery, radiographs of the patient were performed weekly and on the 35th post-surgery day, the bone was completely remodeled and healed, and the animal was dismissed.(AU)

Biomechanical comparison of a new expandable intramedullary nail and conventional intramedullary nails for femoral osteosynthesis in dogs.

Intramedullary nailing of diaphyseal femoral fractures is a commonly used treatment method in dogs because of its biological and biomechanical advantages compared to bone plating. To achieve adequate resistance of the intramedullary nail against torsional and axial compressive forces, additional application of transcortical screws is needed. As these interlocking screws represent a frequent cause of post-operative complications, a new expandable intramedullary nail (EXPN) was developed, which was designed to provide adequate fracture stabilisation without the need for transcortical fixation. The evaluation of the biomechanical properties of the new EXPN with regard to torsional, compressive and bending stability as well as direct comparison to the biomechanical properties of conventional Steinmann (STMN)- and interlocking (ILN) nails was carried out with different biomechanical test arrangements. No significant statistical differences regarding the torsional and bending resistance between the EXPN and ILN group were seen, which indicates that rotatory as well as bending stability of the innovative EXPN is similar to the conventional ILN. Nevertheless, the percentage deviation between the attempted and successfully reached physiological compressive forces was significantly higher (p = 0.045) in the EXPN group compared to the ILN group, which indicates that the compressive stability of the innovative EXPN might be weaker compared to the ILN. In summary, the new EXPN represents an interesting alternative to conventional intramedullary nails. However, in direct comparison to conventional interlocking nails, the EXPN has shown weaknesses in the neutralization of axial compressive forces, which indicates that at least biomechanically the interlocking nail seems advantageous. Further in-vitro and in-vivo investigations are required before clinical use can be recommended.

Advances in Exotic Animal Osteosynthesis.

Exotic animal orthopedics has not incorporated the most recent progress made in small animal surgery or human medicine. Although minimally invasive osteosynthesis has been incorporated as a routinely used alternative in small animals, its use in exotic animals is still in its infancy. This article compliments the reviews of orthopedics in small mammals, birds, and reptiles in the previous issue. It reviews relevant recent studies performed in laboratory animals about new orthopedic materials and techniques showing potential to become incorporated into the routine orthopedic treatment of exotic animals in the coming years.

Biocompatibility of polyamide 12 intramedullary rod after humeral consolidation in white Plymouth Rock birds / Biocompatibilidade de haste intramedular bloqueada de poliamida 12 após consolidação óssea umeral em aves Plymouth Rock branca

Technological and tissue engineering have enabled available, biologically inert, and low cost materials to be considered as viable alternatives in the surgical treatment of long bone fractures in birds. The aim of this study was to microscopically analyse osteotomized humerus of birds following the insertion of solid laser-sintered polyamide 12 rods in order to detect foreign body reaction and, thus, verify the bioinert property of the material in the bone fracture environment. Polyamide 12 intramedullary rods were inserted into the osteotomized humerus of 10 birds (white Plymouth Rock) and blocked using 2mm diameter cortical screws of varying lengths. The birds were operated at 60 days of age and monitored post-operatively for three months. Animals were euthanized at 150 days old and samples of the operated humerus collected for immunohistochemistry, light and scanning electron microscopy analysis. Results show bone consolidation without rejection of the implant and absence of inflammatory cells. Vascular Endothelial Growth Factor (VEGF) was expressed in the endothelial cells of the blood vessels at the site of the newly formed bone surrounding the implant, indicative of local angiogenesis. There was no bone growth on the surface of the rod; however, the implant did not interfere with the circumjacent bone repair. Thus, the findings of this study corroborate with the literature in characterizing polyamide as a bioinert material and, under the studied conditions, it can be concluded that polyamide 12 intramedullary rod is biocompatible and provides adequate bone consolidation in humeral fractures with no signs of rejection.(AU)

Com o desenvolvimento tecnológico e crescimento da engenharia de tecidos, o uso de materiais disponíveis, bioinertes e debaixo custo pode ser alternativa viável para o tratamento cirúrgico de fraturas em ossos longos nas aves. O objetivo do estudo foi realizar avaliação microscópica óssea após a implantação de haste maciça de poliamida, implantada em úmeros osteotomizados de galinhas para detectar reação do tipo corpo estranho, verificando a propriedade "bioinerte" do material no ambiente de fratura óssea. Foram utilizados 10 galos (Plymouth rock branca) e implantou-se a haste perfazendo o bloqueio das mesmas com parafusos corticais de 2 mm de diâmetro com comprimentos de acordo com a necessidade. As aves foram operadas aos 60 dias de vida e o acompanhamento pós-operatório ocorreu por três meses. Após a eutanásia, foram realizadas coletas do úmero operado (local de consolidação óssea) paraexame histopatológico, imuno-histoquímico e de microscopia eletrônica de varredura. Os resultados demonstraram consolidação óssea, sem presença de rejeição do material, com ausência de células inflamatórias. A neoformação óssea ao redor do implante expressou VEGF (fator de crescimento endotelial vascular) nas células endoteliais dos vasos sanguíneos caracterizando angiogênese no local. Na região de interface de tecido ósseo com a poliamida não foram observadas micro fraturas. Não houve crescimento ósseo na superfície da haste, porém a mesma não atrapalhou o reparo ósseo circunjacente. Assim, esse estudo corrobora com a literatura caracterizando a poliamida como um material bioinerte, e nas condições estudadas pode-se concluir que o uso da haste intramedular de poliamida 12 proporcionou consolidação óssea nesse modelo biológico nesse tipo de fratura, não havendo indícios de induzir rejeição.(AU)

Surgical Repair of Radial-Ulnar Fracture by Static Intramedullary Interlocking Nailing in a Crossbred Heifer.

OBJECTIVE: Study included surgical management of radius and ulna fracture in a 2-year-old, 220 kg crossbred heifer presented with a 2-day-old history of injury resulting in severe, non-weight bearing lameness of the left forelimb. METHODS: The condition was diagnosed clinically and confirmed radiographically as a middle third oblique comminuted fracture of the left radius and ulna. Static intramedullary interlocking nailing was performed for fracture fixation. An interlocking nail of 12-mm diameter and 26-cm length was introduced in a retrograde manner from the distal aspect of the radius. RESULTS: The animal was able to bear weight on the affected limb within 7 days post surgery. Good callus formation and complete weight bearing were observed by 35th day. Bending of the screws and osteophytic reaction were the major postoperative complications observed radiographically. CLINICAL SIGNIFICANCE: From this case study, it was established that static intramedullary interlocking nailing can be used as an alternative technique for fracture repair of the radius and ulna in cattle where stable fracture fixation by bone plating is questionable.

Haste intramedular bloqueada em comparação com placa de compressão dinâmica na estabilização de osteotomia intertrocantérica varizante em cães: estudo ex vivo / Interlocking nail system in comparison with dynamic compression plate in the stabilization of intertrochanteric varus osteotomy in dogs: study in cadavers

Tendo em vista as vantagens das hastes intramedulares bloqueadas (HIB) em relação às placas ósseas na estabilização femoral, o presente estudo objetivou avaliar a exequibilidade e eficácia da aplicação da HIB pós osteotomia intertrocantérica varizante (OIV). Submeteu-se 10 cadáveres caninos à OIV. Nos antímeros esquerdos obteve-se a estabilização por meio de HIB (grupo HIB) e, nos direitos, com placas de compressão dinâmica (grupo placa). Foram comparados os ângulos de Norberg e de inclinação da cabeça e colo femoral (ICF) antes (T0) e após (T1) a OIV. O tempo dispendido para a colocação dos implantes e resultados de resistência biomecânica à compressão e torção também foram confrontados entre os grupos. Houve aumento do ângulo de Norberg entre T0 (106,84®5,55o) e T1 (111,22o®3,89), apenas no grupo HIB (p<0,05). No entanto, redução do ângulo de ICF após OIV (T1) foi observada tanto no grupo placa (T0=127,6®4,70o e T1=110,06®10,61o, p<0,05) quanto no grupo HIB (T0=126,43®5,87o e T1=116,87®8,62o, p<0,05). Os tempos de colocação dos implantes não diferiram estatisticamente e apenas o teste biomecânico de compressão revelou diferença entre os grupos, com maior resistência (P=0,033) do grupo placa (863,3®74,46N/mm) em relação ao grupo HIB (586,7®44,10N/mm). Deste modo, a estabilização por meio de HIB foi factível e eficaz. Embora o resultado biomecânico de compressão tenha demonstrado maior fragilidade da HIB em relação à placa de compressão, seus valores estão acima das forças atuantes, reportadas na literatura, na deambulação normal de cão.(AU)

Considering the advantages of the interlocking intramedullary nail (IN) in relation to bone plates in the femoral stabilization, this study aimed to evaluate the feasibility and effectiveness of IN application post intertrochanteric varus osteotomy (IVO). For this purpose, 10 canines cadavers were used. On the left femurs, the fixation was obtained with IN (IN group) and rights fixed with dynamic compression plates and screws (plate group). Was compared the angles of Norberg and inclination of the head and femoral neck (IHF) before (T0) and after (T1) IVO. The results of time spent for placement of implants and biomechanical resistance to compression and torsion were also confronted between groups. There was an increase of the Norberg angle between T0 (106.84®5.55o) and T1 (111.22o®3.89), only in IN group (p<0.05). However, reduction of IHF angle after IVO (T1) was observed in both, the plate group (T0=127.6®4.70o e T1=110.06®10.61o, p<0.05) and IN group (T0=126.43®5.87o e T1=116.87® 8.62 o, p<0.05). The placement times of the implants did not differ statistically and only the compression biomechanical test revealed differences between groups, with greater resistance (P=0.033) of the plate group (863.3®74.46N/mm) compared to IN group (586.7®44.10N/mm). Thus, stabilization through IN was feasible and effective. Although the compression biomechanical results has demonstrated a higher fragility of IN in relation to the compression plate, their values are above the forces, reported in literature, acting in normal dog gait.(AU)

Applicability of polyamide 12 intramedullary locked rods in the stabilization of induced humeral fracture in cockerels (white plymouth rock) - in vivo study / Aplicabilidade da haste intramedular bloqueada de poliamida 12 na estabilização de fratura umeral induzida em galos (Plymouth Rock Branca) - estudo in vivo

The aim of this study was to evaluate the use of polyamide 12 intramedullary rods in osteotomized humerus in cockerels (White Plymouth Rock) and analyze, by radiography and histopathology, bone consolidation and the formation of bone callus. Ten cockerels were subjected to transverse osteotomy of the right humeral diaphysis followed by the insertion of polyamide 12 locked rods, with two nails in each bone fragment. Radiographies obtained at the immediate pre and post-operative period, and every 7 days for 3 months revealed no perioperatory complications. Radiography revealed a radiopaque bone callus between the 4th and 5th week post-surgery. Histopathology detected an amphophylic material (polyamide 12 rod) in the intramedullary region and the proliferation of highly vascularized connective tissue between the rod and the cortical bone. This connective tissue was highly cellular with differentiation into osteoblasts. The collagen fibers varied from loose to dense and a differentiated bone matrix, containing osteocytes in gaps and the development of bone marrow, was also observed; indicating the formation of a bone callus without signs of implant rejection. The polyamide 12 intramedullary rod was effective in the stabilization of the fractures used in this experimental model, with no rejection reaction for at least 90 days.(AU)

O presente estudo teve como objetivo avaliar a implantação de hastes intramedulares de poliamida 12, em úmeros osteotomizados de galos (Plymouth Rock Branca), bem como avaliar a consolidação óssea, por meio da verificação da formação de calo ósseo, analisando exames radiográficos e histopatológicos. Os galos foram submetidos à osteotomia transversa da diáfise do úmero direito, sendo implantadas posteriormente as hastes de poliamida 12 bloqueada com dois parafusos em cada fragmento ósseo. Após o procedimento cirúrgico, foram realizadas radiografias nos momentos pré e pós-operatório imediato e, posteriormente, a cada sete dias, durante três meses, até a realização da eutanásia. Não houve complicações perioperatórias. Ao exame radiográfico, os animais apresentaram formação de calo ósseo radiopaco entre a quarta e quinta semanas de pós-operatório. Ao exame histopatológico, foi possível notar, em todos os animais, presença de material anfofílico (haste de poliamida 12) ocupando a região intramedular óssea, e entre a haste e as corticais ósseas, proliferação de tecido conjuntivo altamente vascularizado. Tal tecido apresentou-se altamente celular com diferenciação em osteoblastos. Notaram-se também fibras colágenas, variando de aspecto frouxo a denso, e observou-se formação de matriz óssea diferenciada com osteócitos em lacunas e formações de medula óssea, denotando formação de calo ósseo sem sinais de rejeição do implante. A haste intramedular de poliamida 12 foi eficaz para estabilização das fraturas utilizando-se esse modelo experimental, sem reação de rejeição pelo período de 90 dias.(AU)

Closed reduction and fluoroscopic-assisted percutaneous pinning of 42 physeal fractures in 37 dogs and 4 cats.

OBJECTIVE: To report complications and clinical outcome of dogs and cats that underwent fluoroscopic-assisted percutaneous pinning (FAPP) of physeal fractures. STUDY DESIGN: Retrospective study. ANIMALS: Client-owned dogs (n = 37) and cats (n = 4). MATERIALS AND METHODS: Records (August 2007-August 2014) of physeal fractures treated with FAPP in 3 hospitals were evaluated. Data collected included signalment, fracture characteristics (etiology, location, duration, Salter-Harris classification, preoperative and postoperative displacement), surgical information (implant size, surgical duration), and outcome assessment information (functional outcome, radiographic outcome, and complications). RESULTS: The majority of animals (92%) were classified as full functional outcome. No significant predictors of functional outcome were identified. The overall complication rate was 15% (n = 6). Elective pin removal rate was 41% (n = 17). Goniometry and limb circumference measurements of the affected and contralateral limbs were not significantly different in dogs for which measurements were obtained. Seventeen of 18 animals (16 dogs, 2 cats) measured had bone length changes on follow-up radiographs. CONCLUSION: FAPP is associated with an excellent functional outcome in a narrow selection of fracture configurations, specifically those with minimal displacement and for which anatomical alignment can be achieved with closed reduction.

Plate failure by bending following tibial fracture stabilisation in 10 cats.

OBJECTIVE: To describe the clinical findings and management of tibial fractures in cats in which osteosynthesis failed due to plate bending. METHODS: Case records and radiographs of cat tibial fracture repairs from five referral centres were reviewed for signalment and to assess incidence of plate failure by bending. Cats that sustained plate bending following plate or plate-rod fixation were reviewed for fracture configuration, repair method, initial postoperative and postfailure tibial alignment, revision treatment and outcome. RESULTS: The incidence of plate bending in cat fractures managed with plate and plate-rod fixation in the four referral centres where the overall number could be established was 13% (8/60). In the 10 cats in which plates bent, initial fractures were generally oblique or spiral with mild comminution and located in the middle or distal third of the tibia. Mean time to implant failure was 24 days (range 2 to 56 days). Mean tibial valgus angle increased from 12·9° to 30·9° following bending of the plate. Short-term outcome following revision surgery using orthogonal plating or stacked medial plates was favourable with improvement in tibial valgus in all five fractures with follow-up data. CLINICAL SIGNIFICANCE: Plate bending following tibial fracture stabilisation in these 10 cats resulted in tibial valgus deformation. Consideration of plate and/or intramedullary rod selection and application should be given to avoid a plate strain environment that exceeds the yield point of the plate.

Early Clinical Experience with a Newly Designed Interlocking Nail System-Targon(®) Vet.

OBJECTIVE: To describe early clinical experience with a newly designed interlocking nail system (Targon(®) Vet) in diaphyseal fractures in cats and small dogs. STUDY DESIGN: Retrospective case series. ANIMALS: Client-owned cats (n=49) and dogs (n=8). METHODS: Fifty-seven consecutive cases (49 cats, 8 dogs) with 60 long bone fractures were included in the study. Follow-up radiographs were scheduled at 4 and 8 weeks and again 6 months postoperatively. The end point for each case was determined radiographically by a healed fracture. Complications were defined as minor or major. Clinical outcome was subjectively assessed by a full orthopedic examination and follow-up radiographs. Descriptive data are reported. RESULTS: Median age of cats was 18 months (range, 3-220 months) and of dogs was 28 months (range, 7-115 months). Median body weight was 3.7 kg (range, 1.67-8.41 kg) for cats and 8.15 kg (range, 2.68-13.6 kg) for dogs. Median radiographic follow-up was 16 weeks. All fractures with follow-up radiographs available (n=46) were healed with no infections reported. A total of 12 postoperative complications occurred: 3 minor (slippage of the locking screws) and 9 major (5 femoral-irritation of the sciatic nerve, stress protection, fracture because of a missed fissure, femoral neck fracture, intra-operative revision with a rod and plate; 4 tibial-3 with protrusion of the distal locking screw through the skin and 1 with in-growth of the intramedullary nail). CONCLUSION: Implantation of the Targon(®) Vet System was feasible in all cases. It provides an alternative system for diaphyseal fracture repair in cats and small dogs.

Pin Size Selection for Normograde Intramedullary Pinning of Distal Humeral Fractures in the Dog.

OBJECTIVE: To determine the optimal intramedullary (IM) pin size for open and percutaneous normograde pinning of the distal humerus. STUDY DESIGN: Ex vivo anatomic study. SAMPLE POPULATION: Sixteen canine cadavers. METHODS: Sixteen pairs of forelimbs were harvested from canine cadavers weighing 25-35 kg. The craniocaudal diameter of the humeral medullary canal, at the distal 80th percentile of its length, was measured on a lateral radiograph. Forelimbs within each pair were allocated to percutaneous or open pinning techniques. Cadavers were divided into three groups based on IM pin diameter relative to the medullary canal diameter: Group 25-35%, Group 36-45%, and Group 46-55%. Pins were inserted normograde into the medial epicondyle and advanced until they exited the proximal humerus. Pin tracts were dissected and damage to soft tissue, bony structures, and location of entry and exit points were documented. The humeri were also cut at the thinnest point of the medial epicondyle and damage to the bone was evaluated. RESULTS: There was no difference in any of the outcomes between the open and percutaneous techniques. Cortical damage was more frequent in Group 46-55% and included blanching and or fracture of the cortex of the medial epicondyle, with fracture occurring in 6/10 limbs in this group. Pins in Group 46-55% exited the farthest and most distal from the optimal exit point and were difficult to place in all limbs. CONCLUSION: This study supports a recommendation for open and percutaneous pinning of the humerus with IM pins 36-45% of the medullary canal diameter measured at the distal 80th percentile of humeral length.

Transfixation pinning and casting of a comminuted metacarpal fracture in a 870 kg bull.

OBJECTIVE: To report metacarpal fracture repair in a bull. STUDY DESIGN: Clinical report. ANIMALS: Simmental bull (n = 1; 870 kg). METHODS: A comminuted right metacarpal fracture was repaired using 2 transfixation pins (6 mm diameter) through the distal metaphysis and diaphysis of the radius and a full limb synthetic resin cast. RESULTS: Slight bending of both pins occurred 1 day after surgery. Both pins were loose and removed at 31 days and a full-limb cast reapplied. The cast was changed at approximately -4 week intervals. On day 50, the right carpus had moderate overextension and a valgus deformity. An exercise program was started on day 62, and on day 110, the cast was replaced with a Robert-Jones-bandage. At 130 days there was circumferential callus formation and the bull was discharged. At 6.5 months, overextension of the right carpus had resolved and carpal valgus had improved. The bull returned to at 7.5 months after surgery, and was successfully used for 4 years. CONCLUSION: For highly valuable cattle like this breeding bull, a surgical treatment of such a fracture should be attempted despite a primarily poor prognosis.

Plates, pins, and interlocking nails.

Evidence-based criteria that promise the best treatment outcome for bovine fracture patients have not been established. Internal fixation with plates and screws allows successful management of many long bone fractures in calves as well as in heavier cattle. Intramedullary pins may be better or equally suited for repair of humerus or femoral fractures in calves, respectively. In richly comminuted fractures in heavy cattle, methods of external fixation are still indicated. With newly introduced locking plates, treatment options for repair of long bone fractures in cattle have further improved, but high costs and a guarded prognosis limit their application.

Femoral fracture repair and sciatic and femoral nerve blocks in a guinea pig.

A four-month-old, entire male guinea pig was presented for surgical repair of a closed oblique femoral fracture. Analgesia was provided with 30 µg/kg buprenorphine intramuscularly (im) four times a day and 0 · 3 mg/kg meloxicam subcutaneously once a day. The following day, anaesthesia was induced and maintained with 100 µg/kg medetomidine im, 20 mg/kg ketamine im, 30 µg/kg buprenorphine im and isoflurane in oxygen. Femoral and sciatic nerve blocks were performed with bupivacaine. The fracture was reduced and aligned using an intramedullary 1 · 4 mm K-wire and a 3 metric polydioxanone cerclage. Three weeks postoperatively remodelling and callus formation was documented, with no evidence of complications. Complete union was present 14 weeks postoperatively.

In vitro biomechanical comparison of the effects of cerclage wires, an intramedullary pin and the combination thereof on an oblique osteotomy of the canine tibia.

OBJECTIVE: To compare the in vitro biomechanical effects of single loop cerclage wires, an intramedullary pin and the combination thereof as applied to an oblique mid-diaphyseal osteotomy of canine tibiae. METHODS: Three groups of nine bones with long oblique osteotomies were repaired with the following methods: 1) Three single loop cerclage wires and a transcortical skewer pin, 2) intramedullary pinning with a smooth Steinmann pin, and 3) a combination of both methods. The repaired constructs were tested in a single cycle four-point-bending test to failure. Load displacement curves were drawn and the following parameters were calculated or extrapolated: Stiffness, load at yield, and force resisted at 2 mm actuator displacement. The latter was determined to demonstrate the difference in the amount of energy absorbed between the different groups. RESULTS: The stiffness and force resisted at 2 mm displacement of the groups with cerclage wires were significantly higher than the group with an intramedullary pin alone (p ≤0.05). The differences in stiffness (p = 0.15) and force required at 2 mm displacement (p = 0.56) between cerclage wires and the combination of cerclage wires and intramedullary pins were not significant. CLINICAL RELEVANCE: Cerclage wire repair results in higher stiffness than repair with an intramedullary pin. When cerclage wires are combined with an intramedullary pin, the intramedullary pin does not provide protection to the cerclage wire repair and the wires or the bone under the wires has to fail before the pin resists significant load.

A finite element model to simulate femoral fractures in calves: testing different polymers for intramedullary interlocking nails.

OBJECTIVE: To verify if the finite element method can correctly estimate the performance of polyacetal and polyamide 6 intramedullary nails in stabilizing a femoral fracture in calves and to estimate the performance of a polypropylene nail in same conditions. STUDY DESIGN: Computational and experimental study. SAMPLE POPULATION: Finite element models (FEMs). METHODS: Based on a 3-dimensional finite element method (FEM) of the femoral diaphysis, 3 models were constructed to simulate an oblique simple fracture stabilized by an intramedullary nail composed of 1 of 3 distinct polymers. Models were tested under 6 loading conditions that simulated a static calf or a calf in different walking phases. Maximum bone and implant stresses were compared to yield and rupture stresses of specific materials. RESULTS: Under static conditions, all polymers were resistant to critical deformation and rupture because maximum von Mises stresses were lower than the respective yield and rupture stresses. However, during walking, maximum stresses exceeded the yield and rupture limits of the polymers, in agreement with a previous in vivo study, which used polyacetal and polyamide nails. CONCLUSIONS: FEM correctly estimated that polyacetal and polyamide 6 nails would fail to immobilize an oblique femoral diaphyseal fracture in calves that were allowed to walk freely during the early postoperative period. FEM can be useful in the development of new bovine orthopedic devices.

Combined intramedullary and external skeletal fixation of metatarsal and metacarpal fractures in 12 dogs and 19 cats.

OBJECTIVE: To report surgical technique, clinical experiences, and long-term outcomes of combined intramedullary/external skeletal fixation of metatarsal (MT) and metacarpal (MC) fractures in dogs and cats. STUDY DESIGN: Case series. ANIMALS: Dogs (n = 12); 19 cats. METHODS: Clinical and radiographic records of animals managed by combined intramedullary/external fixation of MT/MC fractures were reviewed. Signalment, fracture configuration, complications, and subjective clinical findings were recorded. Surgical technique involved retrograde intramedullary pin placement into fractured MT/MC bones, and transverse pin placement in the base of the MT/MCs or tarsal/carpal bones. Contoured pin ends were enshrouded dorsally in epoxy resin and implants maintained until fracture union. Postoperative clinical and radiographic reassessment was performed where possible. RESULTS: Small breed dogs (n = 12) and 19 cats were operated. Fixator removal occurred in < 10 weeks in all cases. Complications included synostosis (n = 2), pin tract discharge (7), excessive postoperative swelling (8), skin abrasions from the frame (2), and paw distortion associated with frame impingement (2). Long-term radiography documented degenerative changes associated with MT-phalangeal or MC-phalangeal joints in 2 dogs; 7 cats, but changes were typically graded mild or moderate and affected only 1 or 2 joints. CONCLUSIONS: Combined intramedullary/external fixation of MT/MC fractures is viable, particularly juxta-articular fractures. Pin penetration of MT-phalangeal or MC-phalangeal joints may cause morbidity and requires further study.