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Objective: To evaluate the change in ex vivo biomechanical properties of the canine cervical spine, due to an intervertebral cage, both as a stand-alone device and in combination with plates., Study Design: Experimental ex vivo study., Animals: Cervical spinal segments (C5-C7) from eight canine cadavers., Methods: The range of motion (ROM) and elastic zone stiffness (EZS) of the spines were determined with a four-point bending device in flexion/extension, lateral bending, and axial rotation for four conditions: native, discectomy, cage (at C6-C7), and cage with plates (at C6-C7). The disc height index (DHI) for each condition was determined using radiography., Results: Discectomy resulted in overall increased ROM (p < .01) and EZS (p < .05) and decreased DHI (p < .005) when compared to the native condition. Placement of the cage increased DHI (p < .001) and restored total ROM during flexion/extension, lateral bending and axial rotation, and EZS during flexion/extension to the level of the native spine. Application of the plates further reduced the total ROM during flexion/extension (p < .001) and lateral bending (p < .001), but restored ROM in extension and EZS during lateral bending. No implant failure, subsidence, or significant cage migration occurred during loading., Conclusion: An anchorless intervertebral cage used as a stand-alone device was able to restore the disc height and spinal stability to the level of the native cervical spine, whereas the addition of plates further reduced the spinal unit mobility., Clinical Significance: This study implies that the intervertebral cage may be used as a stand-alone device in the spinal unit fixation in the canine cervical spine., (© 2021 The Authors. Veterinary Surgery published by Wiley Periodicals LLC on behalf of American College of Veterinary Surgeons.)

Objective: To describe reliable minimally invasive procedures for (1) removing cartilage by joint distraction and articular drilling for equine metacarpophalangeal (MCP)/metatarsophalangeal (MTP) arthrodesis; (2) applying a palmar/plantar tension band without MCP/MTP joint luxation., Study Design: Experimental study., Sample Population: Cadaveric equine limbs (n = 12)., Methods: All limbs were used to evaluate the drilling technique. First the MCP/MTP joint was distracted with a 5.5-mm cortical screw. Then, through four stab incisions, articular cartilage was removed with a 4.5-mm drill. Six randomly chosen limbs were then tested for minimally invasive tension band application with a specially designed cannula. Accurate positioning of the tension band was assessed radiographically. All MCP/MTP joints were disarticulated, and the areas of removed cartilage were visually assessed and measured by using planimetry., Results: The mean percentage of removed cartilage was 66.8% ± 7.6% for the metacarpus/metatarsus surface, 67.9% ± 8.6% for the proximal phalanx surface, and 59.5% ± 1% for the two sesamoid bones. The tension band could be accurately placed through four stab incisions with the cannula., Conclusion: This minimally invasive technique for cartilage removal was efficient and should be favorable for joint fusion in some clinical situations. The minimally invasive tension band application through stab incisions was feasible and repeatable., Clinical Significance: These procedures should allow total minimally invasive MCP/MTP arthrodesis and be used in selected clinical cases., (© 2020 The American College of Veterinary Surgeons.)

Objectives:  To develop the canine vertebral screw and rod fixation system (CVSRF) and to compare the biomechanical properties between CVSRF and the screw and polymethylmethacrylate (Screw-PMMA) technique for internal fixation of the vertebral column in dogs., Methods:  The CVSRF consisted of vertebral screws with monoaxial side-loaded head, rods and specific inner screws connecting rod to the screw head. The CVSRF prototype was made from titanium alloy and manufactured by the rapid prototype machine. Vertebrectomy models were simulated by ultra-high-molecular-weight polyethylene blocks and tested with the CVSRF system ( n  = 8) and the Screw-PMMA technique ( n  = 8). The models were developed according to the American Society for Testing and Materials (ASTM F-1717-04). The biomechanical parameters were the compressive bending yield load, the compressive bending stiffness, the compressive ultimate load and the load displacement curve., Results:  The mean values of the compressive bending yield load, compressive bending stiffness and compressive ultimate load of the CVSRF were significantly higher than those of the Screw-PMMA technique ( p  < 0.01). The load displacement curve of the CVSRF showed higher rigidity and durability than that of the Screw-PMMA technique., Clinical Significance:  This mechanical study indicated that the CVSRF system can be used for canine vertebral stabilization and the biomechanical properties were better than those for the Screw-PMMA device., Competing Interests: The authors declared that they have no conflicts of interest in regard to this manuscript., (Schattauer GmbH Stuttgart.)

Objective: To determine the biomechanical behavior of a novel distraction-stabilization system, consisting of an intervertebral distraction bolt, polyaxial screws, and connecting rods, in the canine lumbosacral spine., Study Design: Biomechanical study., Sample Population: Cadaveric canine lumbosacral spines (L4-Cd3) (N = 8)., Methods: Cadaveric lumbosacral spines were harvested, stripped of musculature, mounted on a 4-point bending jig, and tested in extension, flexion, and lateral bending using nondestructive compressive axial loads (0-150 N). Angular displacement was recorded from reflective optical trackers rigidly secured to L6, L7, and S1. Data for primary and coupled motion were collected from intact spines, after destabilization at L7-S1, and following surgical stabilization with the new implant system., Results: As compared with the intact spine, laminectomy resulted in a modest increase in angular displacement at L6-L7 and a marked increase at L7-S1. Instrumentation significantly reduced motion at the operated level (L7-S1) with a concomitant increase at the adjacent level (L6-L7)., Conclusion: The combination of a polyaxial pedicle screw-rod system and intervertebral spacer provides a versatile solution of surgical stabilization of the lumbosacral joint following surgical decompression in the canine lumbosacral spine. The increase in motion at L6-L7 may suggest the potential for adjacent level effects and clinical trials should be designed to address this question., Clinical Relevance: These results support the feasibility of using this new implant system for the management of degenerative lumbosacral disease in dogs. The increase in motion at L6-L7 may suggest the potential for adjacent level effects and clinical trials should be designed to address this question., (© 2017 The American College of Veterinary Surgeons.)

Objective: To determine the accuracy and safety of pin placement for lateral vertebral stabilization to the reference dorsal stabilization., Study Design: A randomized noninferiority trial., Sample Population: Twenty Greyhound cadaveric lumbar spines (L1-L6)., Methods: One hundred and fifty-nine lumbar vertebral pins placed in 80 vertebrae were assessed; these pins were distributed approximately equally between the dorsal and lateral approaches, and between 2 surgeons. Pin angle accuracy, bone purchase distance, and distances from pin to the spinal canal and the aorta were measured for each pin., Results: The lateral approach was superior for pin angle accuracy and bone purchase. The mean angle of deviation was 15.3° with the dorsal approach and 7.0° with the lateral approach. The mean bone purchase was 16.7 mm with the dorsal approach and 22.2 mm with the lateral approach. Pins were placed at a mean of 2.3 mm from the spinal canal with the dorsal approach and 1.7 mm with the lateral approach. Pins were placed at a mean of 3.8 mm from the aorta with the dorsal approach and 8.0 mm with the lateral approach. The percentage of pins breaching the spinal canal was 14% with the dorsal approach and 19% with the lateral approach. Fourteen percent of pins placed via the dorsal approach breached the aorta, whereas no pins placed via the lateral approach breached the aorta., Conclusion: Relative to the dorsal approach, the lateral approach improves angle accuracy, bone purchase, and distance between pins, and the aorta and is noninferior with regards to the distance between pins and the spinal canal., (© 2017 The American College of Veterinary Surgeons.)

Reasons for Performing Study: Post operative imaging in subjects with orthopaedic implants is challenging across all modalities. Magnetic resonance imaging (MRI) is preferred to assess human post operative musculoskeletal complications, as soft tissue and bones are evaluated without using ionising radiation. However, with conventional MRI pulse sequences, metal creates susceptibility artefact that distorts anatomy. Assessment of the post operative equine patient is arguably more challenging due to the volume of metal present, and MRI is often not performed in horses with implants. Novel pulse sequences such as multiacquisition variable resonance image combination (MAVRIC) now provide improved visibility in the vicinity of surgical-grade implants and offer an option for imaging horses with metal implants., Objectives: To compare conspicuity of regional anatomy in an equine fracture-repair model using MAVRIC, narrow receiver bandwidth (NBW) fast spin echo (FSE), and wide receiver bandwidth (WBW) FSE sequences., Study Design: Nonrandomised in vitro experiment., Methods: MAVRIC, NBW FSE and WBW FSE were performed on 9 cadaveric distal limbs with fractures and stainless steel implants in the third metacarpal bone and proximal phalanx. Objective measures of artefact reduction were performed by calculating the total artefact area in each transverse image as a percentage of the total anatomic area. The number of transverse images in which fracture lines were visible was tabulated for each sequence. Regional soft tissue conspicuity was assessed subjectively., Results: Overall anatomic delineation was improved using MAVRIC compared with NBW FSE; delineation of structures closest to the metal implants was improved using MAVRIC compared with WBW FSE and NBW FSE. Total artefact area was the highest for NBW FSE and lowest for MAVRIC; the total number of transverse slices with a visible fracture line was highest in MAVRIC and lowest in NBW FSE., Conclusion: MAVRIC and WBW FSE are feasible additions to minimise artefact around implants., (© 2015 EVJ Ltd.)

Objectives: To evaluate the influence of titanium mesh on guided bone regeneration when used, either alone or in combination with autogenous bone block graft, in a canine ulnar model., Methods: Thirty-two, purpose bred, adult, castrated male Beagles were used, divided into four equal-size groups. A unilateral mid-diaphyseal ulnar critical-size defect was created in each dog. The ulnar segments were stabilized with a stainless-steel plate and screws. Each defect was managed by: no further treatment (Group A) or by placement of a bone block graft taken from the ipsilateral iliac crest (Group B), or titanium mesh wrapped around the ulna (Group C), or a bone block graft and titanium mesh (Group D). After six months, bone block biopsies were performed and the samples were scanned using micro-computed tomography. Qualitative histological evaluation was performed on two non-decalcified longitudinal sections from each block., Results: No significant differences in terms of mineralized bone volume were detected between the grafted sites (Groups B and D) or between the non-grafted ones (Groups A and C). The histological evaluation indicated good integration of the bone blocks irrespective of the use of titanium mesh., Clinical Significance: The use of titanium mesh does not influence the amount of bone formation. The canine ulnar critical-size defect model seems to be a reliable model to use in experimental studies.

A 4-year-old Shih-Tzu, referred for an enlarged left carpus, was diagnosed with a unicameral bone cyst. A customized titanium device was inserted into cystic lesion and fixed by titanium screws. Sufficient strength of the affected bone with the device inserted to maintain limb function was established after resection of contents of cystic lesion. There was no deterioration of the lesion of bone cyst, and acceptable function of the affected limb with no clinical signs of lameness was maintained during 36 months follow-up. The results of this study demonstrated that bone cyst curettage and use of a customized titanium device could provide an effective alternative treatment of huge lesion of unicameral bone cysts with the intent of preventing pathologic fractures.

Objective: To 1) assess the bending strength and stiffness of canine cadaver spines after fixation of a lumbar spinal fracture-luxation using a novel unilateral stabilization technique with pins and polymethyl methacrylate (PMMA) and 2) compare the results to a reference standard dorsal pin and PMMA technique., Study Design: A randomized non-inferiority trial., Sample Population: Cadaveric lumbar spines (L1-L6) from 20 Greyhounds., Methods: Specimens were paired to match bodyweight and vertebral size. A standardized fracture/luxation was performed between L3 and L4. One spine within each pair was randomly assigned the unilateral fixation technique and the other received the reference standard dorsal fixation technique. Four-point bending of each specimen in flexion was performed by applying load to pins placed transversely into vertebrae L1, L2, L5, and L6. During testing, angular bending strength and stiffness were measured as a function of flexion angle. Margins for non-inferiority were defined a priori. Strength and stiffness of the specimens for each technique were compared statistically., Results: Lower limits of 95% confidence intervals were above the defined margins for non-inferiority. Thus, based on these margins, for strength and stiffness, unilateral fixation was not inferior to dorsal fixation., Conclusions: This novel unilateral approach to lumbar spinal fixation yielded comparable strength and stiffness when tested for bending in flexion to that of reference standard dorsal approach. This approach is therefore a suitable alternative to the dorsal approach in appropriate lumbar spinal fracture configurations., (© Copyright 2014 by The American College of Veterinary Surgeons.)

Bovine fractures are common and each bovine patient is unique, presents innumerable challenges, and requires careful judgment. In cattle the fracture repair usually should be of acceptable quality to not cause a decrease in milk or meat production or interfere with natural breeding. The decision to treat a fracture in cattle is made by evaluating the cost and success rates of the treatment, the value of the animal, and the location and type of fracture., (Copyright © 2014 Elsevier Inc. All rights reserved.)

This report describes the treatment of traumatic carpal hyperextension in a giant breed dog by pancarpal arthrodesis using a custom-made Fixin locking plate, created with the aid of a three-dimensional plastic model of the bones of the antebrachium produced by rapid prototyping technology. A three-year-old 104 kg male Mastiff dog was admitted for treatment of carpal hyperextension injury. After diagnosis of carpal instability, surgery was recommended. Computed tomography images were used to create a life-size three-dimensional plastic model of the forelimb. The model was used as the basis for constructing a customized 12-hole Fixin locking plate. The plate was used to attain successful pancarpal arthrodesis in the animal. Radiographic examination after 74 and 140 days revealed signs of osseous union of the arthrodesis. Further clinical and radiographic follow-up examination three years later did not reveal any changes in implant position or complications.

Purpose: Our research was aimed at studying the radiographic and histological outcomes of using flexible intramedullary nailing (FIN) combined with Ilizarov external fixation (IEF) versus Ilizarov external fixation alone on a canine model of an open tibial shaft fracture., Materials and Methods: Transverse diaphyseal tibial fractures were modelled in twenty dogs. Fractures in the dogs of group 1 (n = 10) were stabilized with the Ilizarov apparatus while it was combined with FIN in group 2 (n = 10)., Results: On day 14, a bone tissue envelope started developing round the FIN wires. Histologically, we revealed only endosteal bone union in group 1 while in group 2 the radiographs revealed complete bone union on day 28. At the same time-point, the areas of cancellous and mature lamellar bone tissues were observed in the intermediary area in group 2. The periosteal layers were formed of the trabeculae net of lamellar structure and united the bone fragments. The frame was removed at 30 days after the fracture in group 2 and after 45 days in group 1 according to bone regeneration., Conclusion: The combination of the Ilizarov apparatus and FIN accelerates bone repair and augments stabilization of tibial shaft fractures as compared with the use of the Ilizarov fixation alone.

The study compares the efficiency of a new bone fixator combining periostal and intramedullary osteosynthesis to bone plating in treatment of tibial fractures in sheep. Experimental osteotomies were performed in the middle third of the left tibia. Animals were divided into two groups: in one group (four animals) combined osteosynthesis (rod-through-plate fixator, RTP fixator) was applied, and in the other group (three animals) bone plating was used. The experiments lasted for 10 weeks during which fracture union was followed by radiography, and the healing process was studied by blood serum markers reflecting bone turnover and by histological and immunohistochemical investigations. In the RTP fixator group, animals started to load body weight on the operated limbs the next day after the surgery, while in the bone plating group, this happened only on the seventh day. In the RTP fixator group, consolidation of fractures was also faster, as demonstrated by radiographical, histological, and immunohistochemical investigations and in part by blood serum markers for bone formation. It can be concluded that application of RTP fixation is more efficient than plate fixation in the treatment of experimental osteotomies of long bones in sheep., (© 2012 Blackwell Verlag GmbH.)

A case of bilateral calcaneal epiphysiolysis in a six-month-old female Dobermann Pinscher is described in this report. The absence of a traumatic event and the clinical, radiographic and histopathological abnormalities led us to the diagnosis of simultaneous bilateral epiphysiolysis of the calcaneus. A tension band and a type II transarticular external fixator were placed. The clinical signs were resolved only temporarily because of the gravity of the bone changes.

The clinical signs, radiographic findings, surgical treatment, and outcome of three horses with luxation of the distal tarsal joints are reported. Two patients showed luxations of the tarsometatarsal joint whereas luxation of the proximal intertarsal joint was found in one case. Open reduction, followed by internal fixation was performed in two horses and closed reduction with a transfixation pin cast was performed in the third. The treatment in all three cases resulted in a satisfactory clinical outcome.

The in vitro biomechanical properties of three methods for internal fixation of femoral neck fractures were evaluated. Fifty cadaveric femura from Beagle dogs were used. Ten intact femora served as controls. In 40 femura, an osteotomy of the femoral neck was performed to simulate a transverse fracture. With the remaining 30 femura, three repair methods (two medium Orthofix pins, a 2.7 mm cortical bone screw placed in lag fashion and an anti- rotational Kirschner wire, or three divergent 1.1 mm Kirschner wires) were used to stabilize the osteotomies, and 10 osteotomies were stabilised per repair method. These 30 femura where then subject to monotonic loading to failure. Construct stiffness and load to failure were measured. In the remaining 10 femura, pressure sensitive film was placed at the osteotomy site prior to stabilization with either two Orthofix pins (n = 5) or a screw placed in lag fashion (n = 5) to determine the compressive pressure (MPa), compressive force (KN) and area of compression (cm²). There was no significant difference in the stiffness or load to failure for the three repair methods evaluated. There was no significant difference in the compressive pressure, compressive force or area of compression in osteotomies stabilized with Orthofix pins and 2.7 mm bone screws.

Objectives: To describe the surgical treatment of pes varus in Dachshund dogs by medial opening wedge osteotomy of the distal tibia stabilized with a locking plate system and to retrospectively report the clinical and radiographic outcomes., Materials and Methods: Lameness in nine limbs of seven Dachshund dogs with pes varus deformity was treated with corrective osteotomy at or near the centre of rotation of angulation as defined by the intersection of the proximal and distal mechanical axes determined on caudo-cranial radiographs. Outcomes evaluated included comparison of pre- and postoperative radiographic measurements of frontal angulation and lameness assessment., Results: Lameness resolved in eight limbs and improved in one limb. All osteotomies healed and no implant complications were detected. Mean preoperative radiographic measurements were: mechanical medial proximal tibial angle (mMPTA) = 91.1° (range 87.6°-95°), mechanical medial distal tibial angle (mMDTA) = 62.1° (range 51.9°-69.6°). Mean postoperative measurements were: mMPTA 92.4° (range 78°-97.5°), mMDTA 81.8° (range 76°-87°). Measurable under- correction was common, though seldom visually or functionally evident., Clinical Significance: Pes varus deformity in Dachshunds can be treated by medial opening wedge osteotomy of the distal tibia stabilized with a locking plate system. Care to preserve the lateral cortex of the osteotomy may help avoid under-correction.

Objective: To evaluate the clinical outcome of minimally invasive plate osteosynthesis (MIPO) for nonarticular tibial fractures stabilized using bone plates with or without an intramedullary rod (IMR)., Study Design: Prospective study., Animals: Dogs (n=28) and 8 cats., Methods: After closed reduction, fracture fixation was achieved using an epiperiosteal plate inserted percutaneously through epiphyseal small incisions. In some fractures, an IMR was inserted via medial parapatellar arthrotomy. Radiographs were recommended every 3 weeks until clinical union. Postoperative tibial length and alignment were compared with contralateral measurements (P<.05). Time to clinical union and complications were recorded., Results: An IMR was used in 30.5% of the cases. Repaired tibiae were 1% shorter than contralateral tibiae (P<.05). Frontal and sagittal alignment were similar between repaired and contralateral tibiae (P>.05). Six dogs were lost for follow-up; owners indicated normal function. In 30 cases for which bone healing was documented, mean±SD healing time was 45±20.8 days; however, when considering the 23 cases, which completed preestablished scheduled follow-ups, healing time was 36±11.6 days. Minor complications occurred in 4 cases (11%). One major complication (3%) consisting of a plate fracture was successfully revised using MIPO with a larger plate., Conclusions: Consistent restoration of alignment was accomplished using MIPO techniques. Furthermore, MIPO appeared to yield faster healing times and lower complication rates than those reported with conventional plate osteosynthesis., (© Copyright 2011 by The American College of Veterinary Surgeons.)

Objective: To assess the reliability of computed tomography (CT) to identify the direction of implant insertion for cortical screws along the longitudinal axis of intact (nonfractured) distal sesamoid bones., Study Design: In vitro study., Sample Population: Cadaveric paired equine forelimbs (n=16)., Methods: Insertion of a cortical screw in lag fashion along the longitudinal axis of intact (nonfractured) distal sesamoid bones was evaluated in 2 groups (3.5 and 4.5 mm) of 8 paired limbs. In each group, the direction of the distal sesamoid bone was determined by CT (Equine XTC 3000 pQCT scanner). Screw placement was verified by specimen dissection. Implant direction was considered satisfactory if the entire screw length was within the distal sesamoid bone and not damaging the articular or flexural surfaces., Results: In our sample and according to our criteria, the proportion of satisfactory direction of screws was 0.63 (5/8) for 4.5 mm implants, and 0.87 (7/8) for 3.5 mm implants., Conclusions: CT is a useful imaging modality to identify anatomic landmarks for insertion of a 3.5 mm cortical screw in the distal sesamoid bone., (© Copyright 2010 by The American College of Veterinary Surgeons.)

Objective: To report surgical planning, technique, and outcome of stabilization surgery in an adult dog with occipitoatlantoaxial malformation (OAAM)., Study Design: Clinical report., Animal: A 19-month-old, 25.5 kg, male castrated, Shiba Inu., Methods: Radiographic and magnetic resonance imaging were used to identify and characterize OAAM. Using a ventral approach to the cranial cervical region 2 cortical bone screws were inserted from the axis into the malformed atlas and occiput., Results: Ambulation was conserved postoperatively. Within 4 weeks, neurologic examination was mostly normal except for decreased proprioception in the right pelvic limb. At 9 months, the dog retained an extended neck posture, but had no neurologic abnormalities., Conclusion: OAAM should be considered as a differential diagnosis in an adult dog with cervical myelopathy. Surgical fixation with cortical bone screws using a ventral approach can be successful., (© Copyright 2010 by The American College of Veterinary Surgeons.)

Objective: To report use of an ulnar interlocking intramedullary nail for repair of an open highly comminuted fracture of the proximal third of the antebrachium in a dog, caused by gunshot., Study Design: Case report., Animals: 1.5-year old, 60 kg, neutered male Mastiff., Methods: An ulnar interlocking intramedullary nail was used to stabilize an open comminuted proximal antebrachial fracture and a cast applied for 4 weeks., Results: Union by secondary bone healing occurred in 8 weeks. At 16 weeks, there was advanced remodeling of the radial and ulnar bony callus and fracture lines were no longer evident. Limb use was normal with normal pain free range of motion of the right elbow., Conclusion: Ulnar interlocking nail is a viable alternative treatment for highly comminuted fracture of the proximal third of the antebrachium in dogs., (© Copyright 2010 by The American College of Veterinary Surgeons.)

Objectives: To (1) define mechanical properties in flexion, extension, and left lateral bending of cadaveric equine 4th and 5th cervical (C4-C5) articulations, (2) compare biomechanical properties of C4-C5 when stabilized with a kerf cut cylinder (KCC) compared with a ventrally placed 4.5 mm locking compression plate (LCP)., Study Design: In vitro biomechanical investigation., Sample Population: Cadaveric adult equine cervical vertebral columns (n=54)., Methods: Cervical vertebrae aged by horse dentition and size measured from radiographs were divided into 3 age groups then randomly allocated to 3 groups. The C4-C5 articulation was treated differently in each of the groups: KCC group; KCC-implanted LCP group; 8-hole 4.5 mm LCP implanted and intact group; no implant. Specimens were randomly subdivided into 1 of 3 loading conditions, before testing to failure under 4-point bending. Stiffness, yield bending moment, failure bending moment, and failure mode were recorded. General linear models were performed to analyze associations between biomechanical properties and test variables., Results: All specimens failed at the C4-C5 intervertebral articulation. The cervical vertebrae with the LCP construct had significantly higher stiffness, yield bending moment, and failure bending moment than the KCC-implanted cervical vertebrae. Failure modes differed between groups and varied with loading direction: KCC group, fractures of C5 associated with the KCC were common; LCP group, screw pull out or fractures (of C4 and C5 bodies, during extension and the caudal aspect of C4 during left lateral bending) were common; and intact group, subluxations were most common., Conclusions: In this model, LCP constructs had superior biomechanical properties compared with KCC constructs. Further research investigating the effect of repetitive loading is indicated., (© Copyright 2010 by The American College of Veterinary Surgeons.)

Objective: To evaluate the use of a locking compression plate (LCP) with monocortical screw purchase for stabilization of the canine cervical spine., Study Design: Experimental study., Animals: Cadaveric canine cervical spine specimens (n = 7)., Methods: Flexion and extension bending moments were applied to canine cadaveric specimens (C3-C6) in 4-point bending, before and after creation of a ventral slot at C4-C5, and after fixation with a 5 hole, 3.5 mm LCP with monocortical screw placement. Screw placement and penetration into the vertebral canal were determined by radiography. Range of motion, stiffness, and energy for passive physiologic loads were determined for the C3-C4, C4-C5, and C5-C6 vertebral motion units (VMU). Monotonic failure properties were determined for cervical extension. Effects of treatments on biomechanical variables were assessed using repeated measures analysis of variance and least square means (P ≤ .05)., Results: The ventral slot procedure increased range of motion at the treated VMU. Plate fixation decreased range of motion, increased stiffness, and decreased energy at the treated VMU. No changes were observed at adjacent VMUs. None of the screws penetrated the vertebral canal. Mean (± SD) yield bending moment of plate stabilized, slotted spines was 15.6 ± 4.6 N m., Conclusion: LCP fixation with monocortical screws stabilized the canine cervical spine., (© Copyright 2010 by The American College of Veterinary Surgeons.)

Objectives: To compare number of cycles to failure for palmarodorsal 4-point bending of a modified 5.5 mm broad locking compression plate (M5.5-LCP) fixation with a 5.5 mm broad LCP (5.5-LCP) fixation used to repair osteotomized equine third metacarpal (MC3) bones., Study Design: In vitro biomechanical testing., Animal Population: Adult equine cadaveric MC3 bones (n=6 pairs)., Methods: An 8-hole, M5.5-LCP, obtained by having a 1.0 mm thickness removed from the bone contact portion of the 5.5-LCP, was applied to the dorsal surface of 1 randomly selected MC3 from each pair, and an 8-hole, 5.5-LCP was applied dorsally to the contralateral bone from each pair using a combination of cortical and locking screws. Plates and screws were applied using standard ASIF techniques to MC3 bones with a mid-diaphyseal osteotomy. MC3 constructs had palmarodorsal 4-point bending cyclic fatigue testing. Mean cycles to failure for each method were compared using a paired t-test within each group. Significance was set at P<.05., Results: Mean±SD cycles to failure of the M5.5-LCP fixation (188,641±17,971) was significantly greater than that of the 5.5-LCP fixation (166,497±15,539)., Conclusion: M5.5-LCP fixation was superior to 5.5-LCP fixation of osteotomized equine MC3 bones in resisting cyclic fatigue under palmarodorsal 4-point bending., Clinical Relevance: This suggests that biological plate fixation is not the ideal choice for osteotomized equine MC3 bones., (© Copyright 2010 by The American College of Veterinary Surgeons.)

Objective: To report biomechanical properties of the Biologic Fixation System (BFX) acetabular cup impacted into a normal canine pelvis and to compare the effect of implant positioned to and beyond the medial acetabular wall., Study Design: In vitro cadaveric study., Animals: Hemipelves of mature, large-breed dogs (n=6)., Methods: For each dog, 1 hemipelvis was reamed to the depth of the acetabular wall (group A) and 1 was reamed an additional 6 mm after penetration of the medial cortex of the acetabulum (group B). The hemipelves were implanted with acetabular cups and loaded in compression through a matching femoral prosthetic component until failure. Specimen stiffness, and failure displacement, load, and energy were determined from load and displacement data and results between groups compared with a paired t-test., Results: Mean failure load was greater in group A (3812 ± 391 N) than group B (2924 ± 316 N; P<.014). No other differences (P>.05) were observed between groups. Bone fracture (n=5) and cup displacement (1) occurred in group A whereas in group B there were 3 fractures and 3 cup displacements., Conclusions: Although medial placement of the BFX cup affected compressive failure loads, failure loads for both groups exceeded normal physiologic loads., Clinical Relevance: Medial positioning of the acetabular cup does not appear to compromise acetabular implant-pelvic stability under normal physiologic loads. Because arthroplasty candidates often have abnormal acetabular architecture, mechanical properties of the cup placed in acetabula without a dorsal rim should be investigated., (© Copyright 2010 by The American College of Veterinary Surgeons.)

To evaluate the effects of IV fentanyl administration on the end-tidal sevoflurane concentration (ET(SEVO)) in thoroughbred racehorses, the ET(SEVO) required for internal fixation of longitudinal fractures was compared between horses anesthetized with sevoflurane-fentanyl (Group SF; n=9) and those anesthetized with sevoflurane alone (Group S; n=9). The loading dose of fentanyl (5.0 µg/kg) was administered over 15 min followed by a maintenance dose of fentanyl (0.1 µg/kg/min) throughout the operation in Group SF. The mean ET(SEVO) during the operation in Group SF (2.6 ± 0.2%) was significantly lower than in Group S (3.0 ± 0.3%). The plasma fentanyl concentrations (6.12 ± 0.88 to 7.78 ± 1.12 ng/ml) in 7 out of 9 horses in Group SF were stable and did not change significantly throughout the operation. The mean dobutamine infusion rate required for maintaining a mean arterial blood pressure between 60 and 80 mmHg during the operation in Group SF (0.56 ± 0.30 µg/kg/min) was significantly lower than in Group S (0.90 ± 0.16 µg/kg/min). The qualities of the recoveries were clinically acceptable, and serious complications were not observed in either group. In conclusion, continuous IV fentanyl administration reduced the sevoflurane requirement by 13% in thoroughbred racehorses undergoing orthopedic surgery; however, fentanyl was considered to be less effective in horses compared with other species.

Objective: To (1) identify prognostic indicators for stability after stabilization of sacroiliac luxation with screws inserted in lag fashion and (2) report dorsoventral dimensions of the sacrum in cats., Study Design: Multicenter retrospective study., Sample Population: Cats (n=40) with sacroiliac luxation., Methods: Case records and radiographs of cats presented at the Queen's Veterinary School Hospital Cambridge and the Royal Veterinary College Hatfield for screw fixation of sacroiliac luxation were reviewed. Dorsoventral dimensions of 15 feline cadaveric sacral bodies were measured to identify the appropriate implant size for use in fixation with screws inserted in lag fashion., Results: Of 40 cats, 13 had left, 14 right, and 13 bilateral sacroiliac luxations. Of 48 screws analyzed, 42 (87.5%) were placed within the sacral body or exited ventrally and 6 (12.5%) were considered malpositioned. Screw purchase within the sacrum was statistically different between unstable and stable repairs (P=.001). Using confidence intervals for screw length within the sacrum and effect on stability, the lowest screw depth that contained 95% of the screws that did not loosen was approximately 60% of the sacral width. Mean dorsoventral sacral dimension at its narrowest point was 5.9+/-1.14 mm. There was no significant difference in the incidence of implant loosening between those luxations that were 100% reduced and those that were <100% reduced (P=.7837)., Conclusions: Screw purchase within the feline sacrum of at least 60% of the sacral width significantly reduces the risk of loosening., Clinical Relevance: Screw placement to a depth of 60% of the width of the feline sacrum is recommended.

This report describes the Fixin internal fixator system(a), a fracture fixation device characterised by a locking conical coupling between screw heads and titanium alloy inserts that are screwed into a stainless steel plate construct. The mechanical principles, implants, instruments and surgical technique are discussed.

Objective: To determine the applicability, complications, and long-term functional outcome of the Kishigami Atlantoaxial Tension Band (Kishigami AATB) for management of congenital and traumatic atlantoaxial (AA) instability in toy breed dogs. STUDY DESIGN; Case series., Animals: Toy breed dogs (n=8) with congenital or traumatic AA instability., Methods: The AA joint of each dog was surgically stabilized through a dorsal approach using the original or a modified version of the Kishigami AATB. Pre- and postoperative neurologic status, radiographs, and complications were reviewed. Follow-up examination was performed at 1 and 12 months., Results: Functional improvement occurred in 5 dogs; 1 dog did not improve or worsen and 2 dogs were euthanatized at owner request. Adequate reduction and stabilization was achieved in 7 dogs based on immediate postoperative radiographs; failure of reduction was evident in 1 dog. No relevant complications occurred., Conclusions: Kishigami AATB may be acceptable as an alternative method for dorsal stabilization of AA subluxation in toy breed dogs in which use of ventral screws or pins is challenging. Experience with this technique in a larger population is necessary to compare our results to those reported by ventral approach. CLINICAL RELEVANCE; The surgical technique described is effective, safe, and simple in the surgical treatment of AA subluxation in toy breed dogs.

Case History: A 5-year-old male Heading dog (working Collie) and a 2-year-old female Huntaway each presented with non-weight-bearing lameness of a hindlimb after jumping or falling with the leg trapped in a gate or motorbike carrier., Clinical Findings: Pain and swelling were localised to the stifle, and radiographs revealed a fracture of the medial condyle of the distal femur in each case., Diagnosis: Medial unicondylar, intra-articular fractures of the distal femur., Clinical Relevance: Open reduction and internal fixation provided an excellent outcome in each case. Open reduction was achieved after elevation of the insertion of the medial collateral ligament from the proximal tibia. Both cases had severe tears to the caudal pole of the medial meniscus, requiring partial meniscectomy. Internal fixation was applied using either divergent K-wires and a biodegradable pin, or a lag-screw technique. The medial collateral ligament was reattached using a 3.5-mm cancellous screw and spiked washer. The therapeutic outcome, i.e. clinical result and return to work, was determined by gait assessment, physical examination, radiography, and an owner's questionnaire. Both working dogs became sound and successfully returned to full work within 6 months of surgery. One dog was subject to euthanasia due to unrelated disease one year after surgery, but the other dog was working fully at 2 years post-operatively; radiography showed osteoarthrosis (OA) but manipulation revealed near-normal range of motion and no loss of muscling.

Locking plates are becoming increasingly popular in veterinary orthopaedics. The SOP is a novel locking plate system, which can be contoured with 6 degrees of freedom and which utilises standard bone screws. The purpose of this work was to investigate the mechanical consequences of contouring the 3.5 SOP plate to support the formulation of clinical guidelines. The implants were loaded in four point bending using an industry standard protocol. The uncontoured SOP was found to be significantly stiffer and stronger than the uncontoured 3.5 DCP. Bending, and to a lesser extent, twisting, diminished the SOP's stiffness and strength but the contoured SOP remained at least as stiff and strong as the untouched DCP.

Objective: To report the use of a human fixation device, the Mennen clamp-on plate (MCOP), for fracture repair in dogs as the sole method of fixation, or in combination with another fixation method such as an intramedullary pin., Methods: The study, which was performed to evaluate the use of the MCOP in fracture repair in dogs, included 36 cases that were selected between 2004 and 2008. The selected cases were all closed diaphyseal fractures, in which sufficient plate prongs could engage the bone on either side of the fracture., Results: Of the 36 cases, 32 had excellent outcomes, and four had complications; these were two cases of fixation failure, one case of osteomyelitis, and one with mild sciatic nerve deficits., Discussion: The MCOP is a promising method for fracture repair on its own for young puppies (six months or less), and in conjunction with other fixation methods in older dogs. It is quick to apply, as no screw holes are created and it achieved a successful outcome in 95% of the cases, provided the cases were appropriately selected for this method., Conclusions: Using the MCOP has produced promising preliminary results in this study and warrants further evaluation.

A four-year-old male Dachshund was presented with pelvic limb paresis due to intervertebral disc extrusion. The spine was surgically explored and decompressed by a bilateral mini-hemilaminectomy and intervertebral disc fenestration at T12-13, and a bilateral pediculectomy of T13. Five days post-operatively, the dog deteriorated because of T13 dorsal laminar subluxation and secondary spinal cord compression. This was surgically investigated and stabilised using bilateral articular facet positional screws and a dorsal spinal plate; the dog subsequently recovered well. Clinically significant spinal instability associated with mini-hemilaminectomy and pediculectomy surgery has not been reported previously.

Fifty-two carpal panarthrodeses (CP) were carried out in 44 dogs (eight bilateral), in a multicentre study using a single (n = 47) or double (n = 5) stepped hybrid CP plate. Of these 44 cases, 39 were between 20-55 kg in bodyweight , 26 were males , and the carpometacarpal was the most common joint involved. Falling and other impact trauma were the most common aetiology. Pain of unknown origin, carpal luxation, chronic accessory carpal bone fracture, distal comminuted intra-articular radial fracture, bone tumour, degenerative joint disease, canine erosive idiopathic polyarthritis, avascular necrosis of the radial carpal bone and fractures of several metacarpal bones were some of the pathologies reported. Fracture of the third metacarpal bone during screw insertion was the only intrasurgical complication. Malpositioning of the plate or screws and over-tightened screws were technical errors observed in seven of the procedures. The radial carpal bone was not fixed with a screw in two cases due to bone deformity. Concurrent plate breakage and bending in the same patient operated on bilaterally was observed during the follow-up period, which represented a major complication rate of 3.8% for all procedures. Minor complications were: low grade infection, lick granuloma, digit hyperextension, screw loosening or failure, incomplete fusion of some joints and a fracture of the third metacarpal bone at the distal screw hole of the plate; which represented a rate of 44.2% on all procedures. Complete carpal healing was observed radiographically in 94.2% of all procedures. Limb function was excellent to good, and all of the owners, except for one, were satisfied with the procedure.

In the 1990s, the AO (Arbeitsgemeinschaft für Osteosynthesefragen) Hand Study Group developed several anatomically bent plates (standard and short) for wrist panarthrodesis in humans. However, only straight plates have been used for carpal panarthrodesis (CP) in animals to date. The primary purpose of this study was to determine if precontoured plates are more anatomical for CP in dogs. Measurement of several of the bones that are implicated in CP, as well as the relationship between their surfaces and the surface of a straight plate, were performed in a radiographic and computed tomographic cadaveric study. Axial and transverse measurements taken at different levels of the metacarpal bones 2, 3 and 4 were also included. The second objective of this study was to develop a more anatomical CP plate according to the results obtained. The measurements and images obtained in this study show that, as in human orthopaedics, bent or stepped plates are more anatomically correct than straight plates for CP in dogs.

Objective: To compare monotonic biomechanical properties and fatigue life of a broad locking compression plate (LCP) fixation with a broad limited contact dynamic compression plate (LC-DCP) fixation to repair osteotomized equine third metacarpal (MC3) bones., Study Design: In vitro biomechanical testing of paired cadaveric equine MC3 with a mid-diaphyseal osteotomy, stabilized by 1 of 2 methods for fracture fixation., Animal Population: Cadaveric adult equine MC3 bones (n=12 pairs)., Methods: MC3 were divided into 3 groups (4 pairs each) for: (1) 4-point bending single cycle to failure testing; (2) 4-point bending cyclic fatigue testing; and (3) torsional single cycle to failure testing. The 8-hole, 4.5 mm LCP was applied to the dorsal surface of 1 randomly selected bone from each pair. One 8-hole, 4.5 mm LC-DCP) was applied dorsally to the contralateral bone from each pair. All plates and screws were applied using standard ASIF techniques. All MC3 bones had mid-diaphyseal osteotomies. Mean test variable values for each method were compared using a paired t-test within each group. Significance was set at P<.05., Results: Mean yield load, yield bending moment, composite rigidity, failure load and failure bending moment, under 4-point bending, single cycle to failure, of the LCP fixation were significantly greater than those of the LC-DCP fixation. Mean cycles to failure for 4-point bending was significantly greater for the LCP fixation compared with LC-DCP fixation. Mean yield load, mean composite rigidity, and mean failure load under torsional testing, single cycle to failure was significantly greater for the broad LCP fixation compared with the LC-DCP fixation., Conclusion: The 4.5 mm LCP was superior to the 4.5 mm LC-DCP in resisting the static overload forces (palmarodorsal 4-point bending and torsional) and in resisting cyclic fatigue under palmarodorsal 4-point bending., Clinical Relevance: The results of this in vitro study may provide information to aid in the selection of a biological plate for the repair of equine long bone fractures.

Objectives: To compare monotonic biomechanical properties and fatigue life of a 5.5 mm broad limited-contact dynamic compression plate (5.5-LC-DCP) fixation with a 4.5 mm broad LC-DCP (4.5-LC-DCP) fixation to repair osteotomized equine third metacarpal (MC3) bones., Study Design: In vitro biomechanical testing of paired cadaveric equine MC3 with a mid-diaphyseal osteotomy, stabilized by 1 of 2 methods for fracture fixation., Sample Population: Adult equine cadaveric MC3 bones (n=18 pair)., Methods: MC3 were divided into 3 test groups (6 pairs each) for: (1) 4-point bending single cycle to failure testing; (2) 4-point bending cyclic fatigue testing; and (3) torsional single cycle to failure testing. The 8-hole, 5.5 mm broad LC-DCP (5.5-LC-DCP) was applied to the dorsal surface of 1 randomly selected bone from each pair. One 8-hole, 4.5 mm broad LC-DCP (4.5-LC-DCP) was applied dorsally to the contralateral bone from each pair. Plates and screws were applied using standard ASIF techniques. All MC3 bones had mid-diaphyseal osteotomies. Mean test variable values for each method were compared using a paired t-test within each group. Significance was set at P<.05., Results: Mean yield load, yield bending moment, composite rigidity, failure load and failure bending moment under 4-point bending, single cycle to failure, of the 5.5-LC-DCP fixation were significantly greater (P<.024) than those of the 4.5-LC-DCP fixation. Mean cycles to failure for 4-point bending was significantly (P<.05) greater for the 4.5-LC-DCP fixation compared with the 5.5-LC-DCP fixation. Mean yield load, mean composite rigidity, and mean failure load in torsion for the 5.5-LC-DCP fixation was not significantly different (P>.05) than those with the 4.5-LC-DCP fixation., Conclusion: 5.5-LC-DCP fixation was superior to 4.5-LC-DCP fixation in resisting the static overload forces under palmarodorsal 4-point bending. There was no significant difference between 5.5-LC-DCP fixation and 4.5-LC-DCP fixation in resisting static overload forces under torsion; however, the 5.5-LC-DCP offers significantly less stability (80% of that of the 4.5-LC-DCP) in cyclic fatigue testing., Clinical Relevance: The results of this in vitro study may provide information to aid in the selection of a biological plate for long bone fracture repair in horses.

Repair of a Salter-Harris type IV dicondylar humeral fracture was performed on a 15-week-old pitbull terrier. Interfragmentary compression of the intracondylar component of the fracture was achieved with a transilial rod and locking nuts (Trans-ilial Rod; IMEX Veterinary, Inc.). The transilial rod was articulated with a modified type I external fixator which functioned as adjunctive stabilisation for the supracondylar component of the fracture. Fracture healing was confirmed radiographically five weeks following surgery. The dog had no appreciable lameness when examined 12 months after fracture repair.

An extensible internal device (EID) was developed to preserve growth plate during the treatment of fracture complications or segmental bone loss from tumour resection in children. Since this type of extensible, transphyseal, internal fixation device has only been used in a few paediatric cases; the aim of this study was to evaluate an in vivo canine study, a surgical application of this device, and its interference with longitudinal growth of the non-fractured distal femur. Ten clinically healthy two- to three-month-old poodles weighing 1.5-2.3 kg were used. Following a medial approach to the right distal femur, one extremity of the EID, similar to a T-plate, was fixed in the femoral condyle with two cortical screws placed below the growth plate. The other extremity, consisting of an adaptable brim with two screw holes and a plate guide, was fixed in the third distal of the femoral diaphysis with two cortical screws. The EID was removed 180 days after application. All of the dogs demonstrated full weight-bearing after surgery. The values of thigh and stifle circumferences, and stifle joint motion range did not show any difference between operated and control hindlimbs. The plate slid in the device according to longitudinal bone growth, in all but one dog. In this dog, a 10.5% shortening of the femoral shaft was observed due to a lack of EID sliding. The other dogs had the same longitudinal lengths in both femurs. The EID permits longitudinal bone growth without blocking the distal femur growth plate if appropriately placed.

The purpose of this study was to determine the biomechanical properties of feline long bone by testing cadaver bone from mature cats in compression, three-point bending, notch sensitivity and screw pull-out strength. The determination of these properties is of clinical relevance with regard to the forces resulting in long bone fractures in cats as well as the behaviour and failure mode of surgical implants utilized for fracture stabilization and repair in the cat. Cadaveric cat femurs were tested in compression, three-point bending and in three-point bending after the addition of a 2.0 mm screw hole. Cortical screws, 2.7 mm in diameter, were inserted in cadaveric cat femur samples for screw pull-out testing. The mean maximum load to failure of mid diaphyseal feline femurs tested in compression was 4201+/-1218 N. Statistical analysis of the parameter of maximum load tested in compression revealed a statistical difference between sides (p=0.02), but not location (p=0.07), or location by side (p=0.12). The maximum strength of mid diaphyseal feline femurs tested in compression was 110.6+/-26.6 MPa. The modulus of elasticity of mid-diaphyseal cat femurs tested in compression was determined to be 5.004+/-0.970 GPa. The mean maximum load to failure of feline femurs tested in three-point bending was 443+/-98 N. The mean maximum load to failure of feline femurs tested in three-point bending after a 2.0 mm diameter hole was drilled in the mid-diaphyseal region of each sample through both cortices was 471+/-52 N. The mean maximum load required for screw pull-out of 2.7 mm cortical screws placed in feline femurs tested in tension was 886+/-221 N. This data should be suitable for investigating fracture biomechanics and the testing of orthopaedic constructs commonly used for fracture stabilization in the feline patient.

Case Description: A 1-year-old 7.4-kg (16.3-lb) castrated male mixed-breed dog was evaluated because of intermittent lameness and an antebrachial angular limb deformity., Clinical Findings: The left forelimb had gross antebrachial external rotation (approx 90 degrees ) and marked procurvatum. Radiography revealed a severe partially compensated biapical antebrachial angular limb deformity. Measurements of medial proximal radial angle (MPRA) and lateral distal radial angle (LDRA) were obtained from orthogonal radiographs of the proximal and distal segments of the radius, respectively. Elbow joint-to-carpus translation was quantified. Deformities were localized and quantified by the center of rotation of angulation (CORA) method. Computed tomographic 3-dimensional image reconstructions of the antebrachium and carpus were completed to create 3 life-size stereolithographic models., Treatment and Outcome: 2 closing wedge radial osteotomies were performed at the level of the CORAs and stabilized with bone plates and screws., Results: Frontal and sagittal plane alignments were corrected to 8 degrees and 15 degrees , respectively (reference limits, 0 degrees to 8 degrees and 8 degrees to 35 degrees , respectively). The MPRA was corrected from 55 degrees to 68 degrees , and LDRA was corrected from 32 degrees to 76 degrees (values considered normal are approx 85 degrees and 87 degrees , respectively). Elbow joint-to-carpus translation was improved by 42.5%. After 8 weeks, radiography revealed bone union. Owners considered the outcome acceptable, on the basis of limb appearance and lack of lameness at 1 year after surgery., Conclusions and Clinical Relevance: A segmental radiographic planning technique combined with the CORA method, computed tomography, and stereolithography may be useful in the characterization of and planning corrective surgery for forelimb deformities in dogs.

Locking plate technologies are being developed in order to provide the surgeon with advantages over previous bone plate systems (both locking and non-locking). Locking plate systems possess inherent biological advantages in fracture fixation by preserving the periosteal blood supply, serving as internal fixators. It is important to consider the strength of each orthopaedic implant as an important selection criterion while utilizing the reported advantages of locking plate systems to prevent catastrophic fracture failure. Mechanical testing of orthopaedic implants is a common method used to provide a surgeon with insight on mechanical capabilities, as well as to form a standardized method of plate comparison. The purpose of this study was to demonstrate and to quantify observed differences in the bending strength between the LCP (Limited Contact Plate), LC-DCP, 3.5 mm Broad LC-DCP (Limited Contact Dynamic Compression Plate), and SOP (String of Pearls) orthopaedic bone plates. The study design followed the ASTM standard test method for static bending properties of metallic bone plates, which is designed to measure mechanical properties of bone plates subjected to bending, the most common loading encountered in vivo. Single cycle four point bending was performed on each orthopaedic implant. The area moment of inertia, bending stiffness, bending strength, and bending structural stiffness were calculated for each implant. The results of this study demonstrated significant differences (p<0.001) in bending strength and stiffness between the four orthopaedic implants (3.5 Broad LC-DCP>SOP>LCP=LC-DCP). The 3.5 mm LCP should be expected to provide in vivo strength and stiffness similar to a comparable LC-DCP. The SOP should provide strength and stiffness that is greater than a comparable LC-DCP but less than a 3.5 mm Broad LC-DCP.

The biomechanical testing of tubes made of third generation short glass fibre-reinforced (SGFR) material approximating cat femurs was performed in order to determine their suitability as cat femur surrogates for the biomechanical testing of orthopaedic implants. The tubes were tested in compression, three-point bending, notch testing, and screw pullout. Thin walled (B1-tubes) had a 13% lower maximum load to failure, a 19% higher maximum strength and a 13% lower elastic modulus compared to cat femurs tested in compression. B1-tubes maximum load to failure in three-point bending and screw pullout strength were considerably lower compared to cat femurs (29% and 63%, respectively). Notch testing was not performed on B1-tubes due to low bending strength. Thicker walled (B2-tubes) had a 23% higher maximum load to failure, a 10% higher maximum strength and a 21% lower elastic modulus compared to cat femurs tested in compression. The comparison of B2-tubes and cat femurs in three-point bending revealed a 7% increase in maximum load to failure for the B2-tubes. Drilled B2-tubes (notch testing) were weaker with a 30% lower load to failure compared to cat femurs. A screw pullout comparison of B2-tubes and cat femurs revealed a 2% increase in maximum load to failure for the B2-tubes. These tubes were intended to provide a model as a suitable surrogate for cat femurs for testing the bending strength of various orthopaedic constructs involving plates and screws. Testing revealed that third generation SGFR tubes were not suitable for these purposes and emphasizes the need to carefully evaluate the suitability of any model.

Several techniques have been described for canine pancarpal arthrodesis (PCA) with dorsal plating becoming the most accepted method for ease of placement despite the proposed biomechanical disadvantages. The aim of this study was to compare the biomechanical effects of the addition of crossed K-wires to a standard 2.7/3.5 mm hybrid PCA plate. A 2.7/3.5 mm hybrid PCA plate, alone and combined with crossed K-wires were tested. Six pairs of cadaver forelimbs were collected from medium-sized dogs with an average weight of 24 kg by elbow disarticulation. The limbs were potted and fixed in an Instron load cell (Instron, High Wycombe, UK) and axially loaded to failure. Load displacement data and mode of failure were recorded and stiffness, yield load and ultimate load at failure were calculated. The yield load (kN) of the plate and K-wire construct (1.278+/-0.11) was significantly higher than for the plate construct alone (1.002+/-0.07) (p=0.00056). However, the differences between the two constructs in stiffness and failure loads were not significant.

Objective: To compare the stiffness and strength of AO bone plates (DCP, LC-DCP, VCP, RCP, and LP) and the Clamp-Rod Internal Fixation System (CRIF)., Study Design: In vitro., Sample Size: 12 individual implants of 18 plate dimensions and four sizes of CRIF, each corresponding to 2.0, 2.4/2.7, 3.5, or 4.5 mm screw sizes., Methods: Implant-constructs of each plate and CRIF were created using Canevasit rods as a bone substitute in an unstable gap fracture model. Six implant-constructs of each type were tested under single cycle four-point bending loading, and six were tested under single cycle torsional loading until permanent plastic deformation occurred., Results: Torsional stiffness and yield load of the DCP were always significantly greater than the CRIF within the same group. Bending properties of the 2.0 DCP were not significantly different to the 2.0 CRIF. The 2.7 DCP had significantly higher bending values than the 2.7 CRIF. The bending stiffness of the 3.5 DCP and 4.5 DCP was significantly less than their CRIF counterparts. While the bending yield load of the 3.5 DCP was significantly greater than the 3.5 CRIF, the bending yield load of the 4.5 DCP was significantly less than the 4.5 CRIF., Conclusion: A weakness was found in the torsional resistance of the CRIF constructs compared to the DCP constructs., Clinical Significance: Bone holding power and applied screw torque should be considered when using the CRIF system in clinical application.

Objective: To determine outcome, report complications, and risk factors for complications associated with the surgical treatment of fractures of the lateral aspect of the humeral condyle (FLHC) in dogs., Study Design: Fifty dogs with FLHC that had been repaired surgically were included in this retrospective case series., Methods: The medical records and radiographs from 50 dogs with FLHC from 1990--2006 were analyzed., Results: The complication rate was 30%. For every 30-minute increase in surgical time the odds of a complication increased by 2.00 (95% CI: 1.06, 3.77). For every 10 degrees increase in the angle between the transcondylar screw and a line between the epicondyles viewed on a craniocaudal radiograph there was a 4.82 (95% CI: 1.23, 18.86) greater odds of an intracondylar fracture gap appearing on postoperative radiographs. When an intracondylar fracture gap was present after surgery there was a 25% long-term radiographic outcome failure rate, whereas there was a 0% radiographic failure rate in the dogs in which an intracondylar fracture gap was not present. In conclusion, transcondylar screw placement parallel to the epicondylar line should be attempted for the repair of FLHC. An increase in surgical time leads to an increase in postoperative complication rate. The presence of an intracondylar fracture gap may be associated with fracture failure., Clinical Significance: Screw angulation predisposed to postoperative intracondylar fracture gap which in turn may be associated with higher fracture fixation failure rate. The dogs that had prolonged surgical times had an increased complication rate.

Objective: To compare failure mode and bending moment of a canine pancarpal arthrodesis construct using either a 2.7 mm/3.5 mm hybrid dynamic compression plate (HDCP) or a 3.5 mm dynamic compression plate (DCP)., Study Design: Paired in vitro biomechanical testing of canine pancarpal arthrodesis constructs stabilized with either a 2.7/3.5 HDCP or 3.5 DCP., Sample Population: Paired cadaveric canine antebrachii (n=5)., Methods: Pancarpal arthrodesis constructs were loaded to failure (point of maximum load) in 4-point bending using a materials-testing machine. Using this point of failure, bending moments were calculated from system variables for each construct and the 2 plating systems compared using a paired t-test. To examine the relationship between metacarpal diameter and screw diameter failure loads, linear regression was used and Pearson' correlation coefficient was calculated. Significance was set at P<.05., Results: HDCP failed at higher loads than DCP for 9 of 10 constructs. The absolute difference in failure rates between the 2 plates was 0.552+/-0.182 N m, P=.0144 (95% confidence interval: -0.58 to 1.68). This is an 8.1% mean difference in bending strength. There was a significant linear correlation r=0.74 (P-slope=.014) and 0.8 (P-slope=.006) between metacarpal diameter and failure loads for the HDCP and 3.5 DCP, respectively., Conclusion: There was a small but significant difference between bending moment at failure between 2.7/3.5 HDCP and 3.5 DCP constructs; however, the difference may not be clinically evident in all patients., Clinical Relevance: The 2.7/3.5 HDCP has physical and mechanical properties making it a more desirable plate for pancarpal arthrodesis.

Objective: To compare the biomechanical properties of cervical arthroplasty to a ventral slot procedure and pin-polymethylmethacrylate (pin-PMMA) fixation., Sample Population: Fresh cadaveric cervical (C2-T1) spines from 6 large dogs., Methods: Four spinal conditions were studied in each spinal specimen: intact, disk arthroplasty, ventral slot, and fixation with smooth pin-PMMA at C5-C6 intervertebral space. Axial compression, torsion, flexion-extension, and lateral bending moments were sequentially tested on each specimen for the 4 spinal conditions. Data from the C3-C4, C4-C5, C5-C6, and C6-C7 vertebral motion units (VMUs) were compared among treatments., Results: In axial compression and torsion, the ventral slot procedure allowed significantly less motion than intact, pin-PMMA, and arthroplasty groups at C5-C6. In lateral bending and flexion-extension, pin-PMMA had the least motion of C5-C6, followed by the arthroplasty group, intact spine, and ventral slot, all of which were significantly different from each other. Overall, the artificial disk was better able to mimic the behavior of the intact specimens compared with the ventral slot and pin-PMMA, producing similar displacements in axial compression and rotation in torsion, but more limited motion than intact in flexion-extension and in lateral bending., Conclusion: Cervical spine specimens with an implanted prosthesis have biomechanical behaviors more similar to an intact spine compared with spinal specimens with ventral slot and pin-PMMA procedures. Cervical arthroplasty may then preserve some of the motion in the affected area after neural decompression while providing distraction., Clinical Relevance: Cervical arthroplasty should be further investigated in vivo to determine if it is a viable alternative to the ventral slot or pin-PMMA procedures for surgical treatment of cervical diseases in dogs and in particular for treatment of disk-associated caudal cervical spondylomyelopathy.