Mechanical assessment of two hybrid plate designs for pancarpal canine arthrodesis under cyclic loading.

Pancarpal canine arthrodesis (PCA) sets immobilization of all three carpal joints via dorsal plating to result in bony fusion. Whereas the first version of the plate uses a round hole (RH) for the radiocarpal (RC) screw region, its modification into an oval hole (OH) in a later version improves versatility in surgical application. The aim of this study was to mechanically investigate the fatigue life of the PCA plate types implementing these two features-PCA-RH and PCA-OH. Ten PCA-RH and 20 PCA-OH stainless steel (316LVM) plates were assigned to three study groups (n = 10). All plates were pre-bent at 20° and fixed to a canine forelimb model with simulated radius, RC bone and third metacarpal bone. The OH plates were fixed with an RC screw inserted either most proximal (OH-P) or most distal (OH-D). All specimens were cyclically tested at 8 Hz under 320 N loading until failure. Fatigue life outcome measures were cycles to failure and failure mode. Cycles to failure were higher for RH plate fixation (695,264 ± 344,023) versus both OH-P (447,900 ± 176,208) and OH-D (391,822 ± 165,116) plate configurations, being significantly different between RH and OH-D, p = 0.03. No significant difference was detected between OH-P and OH-D configurations, p = 0.09. Despite potential surgical advantages, the shorter fatigue life of the PCA-OH plate design may mitigate its benefits compared to the plate design with a round radiocarpal screw hole. Moreover, the failure risk of plates with an oval hole is increased regardless from the screw position in this hole. Based on these findings, the PCA plate with the current oval radiocarpal screw hole configuration cannot be recommended for clinical use.

Outcome of rest with or without bandaging for treatment of carpal flexural contracture deformities in puppies: 47 puppies and 75 joints (2000-2018).

OBJECTIVE: To review outcome of dogs with carpal flexural contracture deformities treated with rest alone or with rest and bandaging. ANIMALS: 47 dogs (75 joints). PROCEDURES: Medical records of dogs with unilateral or bilateral carpal flexural contracture deformities were reviewed, and dogs were grouped according to deformity severity grade (graded on a scale from 1 to 3) at the time of diagnosis. Two treatment groups were compared: rest only and rest with a modified Robert-Jones bandage. All dogs were reevaluated weekly until recovery (ie, resolution of the deformity and lameness). RESULTS: All dogs responded to conservative management, with all dogs regaining full extension of the antebrachiocarpal joint and ambulating normally at the time of the final visit. Mean ± SD time from initial diagnosis to recovery (ie, resolution of the deformity and lameness) was 2.9 ± 2.2 weeks (median, 2 weeks; range, 1 to 9 weeks). For dogs with grade 1 or 2 severity, mean time to recovery did not differ significantly between treatment groups. For dogs with grade 3 severity, however, mean time to recovery was significantly shorter for dogs treated with rest and bandaging than for dogs treated with rest alone. CLINICAL RELEVANCE: Results suggested that conservative management (rest alone or rest and bandaging) was a successful treatment option for puppies with carpal flexural contracture deformity and that bandaging resulted in a shorter time to recovery for dogs that were severely affected.

Mechanical Evaluation of Two Hybrid Locking Plate Designs for Canine Pancarpal Arthrodesis.

Hybrid locking pancarpal arthrodesis plates were designed with either a round (RH) or an oval (OH) radiocarpal hole, the latter allowing varied screw positioning. Due to concerns about potential decreased structural properties of the OH design, our aim was to compare the mechanical behavior of the contrasting plates using combined finite element analysis (FEA) and mechanical testing. Pancarpal arthrodesis plates with RH or OH design were assigned to three fixation techniques (n = 6), prebent at 20°, and fixed to canine forelimb models with simulated radius and radiocarpal and 3rd metacarpal bones. OH plates were instrumented with a radiocarpal screw inserted either most proximal (OH-P) or most distal (OH-D). Specimens were axially loaded to 300 N over 10 ramped cycles at 0.5 Hz. Plate strains were measured with strain gauges placed at areas of highest deformations as predicted by FEA under identical loading conditions. FEA predicted the highest strains (µm/m) adjacent to the radiocarpal hole (2,500 [RH], 2,900 [OH-P/OH-D]) and plate bending point (2,250 [RH], 1,900 [OH-P/OH-D]). Experimentally, peak radiocarpal hole strains were not influenced by the OH screw position (3,329 ± 443 [OH-P], 3,222 ± 467 [OH-D]; P = 0.550) but were significantly higher compared to the RH design (2,123 ± 154; P < 0.001). Peak strains at the bending point were significantly lower for OH-P (1,792 ± 174) and OH-D (1,806 ± 194) versus RH configurations (2,158 ± 114) (P ≤ 0.006). OH plates demonstrated highest peak strains next to the radiocarpal hole and were associated with more heterogenous plate strain distribution. Structural weakening associated with radiocarpal OH plate design could result in decreased fixation strength and increased risk of plate fatigue failure.

Radiographic Recognition of Tarsal Malformation in 8- to 9-Week-Old Bernese Mountain Dogs.

INTRODUCTION: Tarsal malformation is a skeletal malformation of unknown aetiology associated with a variety of morphologic changes to the tarsal and metatarsal bones of the dog. OBJECTIVE: The aim of this study was to determine if early diagnosis and prevalence of tarsal malformation could be obtained at approximately 8 to 9 weeks of age in multiple litters of Bernese Mountain dogs. METHODS: A prospective study of 51 Bernese Mountain dog puppies were evaluated from 12 litters in northern Italy. Dorsoplantar radiographic views of the tarsus were obtained at 60 ± 5 days of age. Tarsal malformation was defined as an abnormal extension of the central tarsal bone on its medial side, or the presence of ectopic bone located medially to the central tarsal bone, talus and second metatarsal bones (proximomedial, distomedial and metatarsal ossification sites respectively). RESULTS: All puppies were found to be clinically normal. Thirty-nine of the 51 puppies showed ossification sites medial to the tarsus as defined. A metatarsal ossification was present in all dogs with either a proximo- or distomedial ossification site. No central tarsal bone extensions were observed. The remainder of the tarsometatarsal joints were normal. CLINICAL SIGNIFICANCE: Tarsal malformation can be identified in the 8- to 9-week-old Bernese Mountain dog. The clinical significance of tarsal malformation remains to be determined, either as an incidental finding or a precursor to the development of other clinically relevant and related issues in the tarsus.

Fractures of the Second Cervical Vertebra in 66 Dogs and 3 Cats: A Retrospective Study.

BACKGROUND: In human medicine, fractures of the second cervical vertebra have been studied elaborately and categorized in detail. This is not the case in veterinary medicine where clinical decisions are often based on old studies focusing on the cervical spine in general. OBJECTIVES: The aim of this study was to describe the clinical features, fracture types, therapeutic options and outcome of dogs and cats with a fractured axis. STUDY DESIGN: The present study was a multi-institutional retrospective case series. RESULTS: Crossbreeds and Labrador Retrievers were the most represented dog breeds. Median age was 2 years. Motor vehicle accident was the most common inciting cause, followed by frontal collision. The most common neurological deficits ranged from cervical pain with or without mild ataxia (22/68) to tetraparesis (28/68) and tetraplegia (11/68). Concerning treatment, 37 of 69 patients underwent surgical fracture stabilization, 27/69 received conservative therapy and 5/69 were immediately euthanatized. Of all treated cases, 52/58 showed ambulatory recovery (23/25 of the conservatively treated and 29/33 of the surgically treated cases), whereby in 40/52 cases full recovery without persisting signs was achieved. CONCLUSIONS: Fractures of the axis commonly occur in young dogs. In many cases, neurological deficits are relatively mild. Generally, animals with a fractured axis have a very good prognosis for functional recovery. The risk of perioperative mortality is considerably lower than previously reported.

Retrospective analysis of corrosion and ion release from retrieved cast stainless steel tibia plateau leveling osteotomy plates in dogs with and without peri-implant osteosarcoma.

OBJECTIVE To evaluate and compare surface and cross-sectional structure as well as localized electrochemical corrosion and ion release for cast stainless steel (SS) tibia plateau leveling osteotomy (TPLO) plates retrieved from dogs with and without osteosarcoma (OSA) and to compare these findings with similar variables for forged SS TPLO plates retrieved from dogs. SAMPLE 47 TPLO plates explanted from 45 client-owned dogs (22 cast plates from dogs with OSA, 22 cast plates from dogs without OSA, and 3 forged plates from dogs without OSA). PROCEDURES Histologic evaluations of tissue samples collected from implant sites at the time of plate retrieval were performed to confirm implant site tumor status of each dog. Surfaces and metallographic cross sections of retrieved plates were examined, and the microcell technique was used to obtain local electrochemical corrosion and ion release measurements. RESULTS Findings indicated that all cast SS plates demonstrated high spatial variability of their electrochemical surface properties and inhomogeneous superficial and cross-sectional composition, compared with forged plates. Greater metal ion release was observed in cast plates than in forged plates and in cast plates from dogs with OSA than in cast or forged from dogs without OSA. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that accumulation of metal ions from implants could be a trigger for neoplastic transformation in neighboring cells. Metal ion release caused by corrosion of implants that do not comply with recommended standards of the American Society for Testing and Materials International or the International Organization for Standardization could potentially place patients at increased risk of tumor development.

Bilateral Radial Agenesis in a Cat Treated with Bilateral Ulnocarpal Arthrodesis.

OBJECTIVE: This article describes corrective antebrachiocarpal re-alignment and arthrodesis for bilateral radial hemimelia (radial agenesis) in an 8-month-old domestic short-haired cat. METHODS: Bilateral forelimb deformity of ulnocarpal varus with complete luxation and rotation of the antebrachiocarpal joint spaces, and joint contracture, was observed. Several carpal bones and metacarpal bones I and II and their associated phalanges were absent. Abnormal ambulation and weight bearing on the dorsolateral part of the manus were present. The deformities were treated by bilateral distal ulnar ostectomy and ulnocarpal arthrodesis using a 2.0-mm locking compression plate applied with hybrid fixation and allograft. RESULTS: Successful deformity correction was obtained with subsequent fusion of the antebrachiocarpal joints. No complications were observed. At long-term follow-up (4.75 years), there was good-to-excellent functional result, with approximately 15° internal rotation of the right forelimb manus and shortened stride with slight circumduction and lameness. All implants remained stable and continued bone remodelling was present. The cat was assessed to have good-to-excellent short- and long-term functional results with excellent owner satisfaction. CLINICAL SIGNIFICANCE: Treatment of radial agenesis in the cat has previously been limited to conservative management or limb amputation. While there are several reports of corrective limb-sparing procedures used to treat dogs, this is the first report of a cat with successful salvage corrective surgery.

Treatment of a Paediatric Distal Femoral Malunion Deformity.

OBJECTIVE: The aim of this article was to describe the surgical re-alignment technique and stabilization of a distal femoral deformity in a 6-week-old, male, Foxhound. METHODS: A healing metaphyseal fracture, resulting in a valgus deformity with internal rotation, was observed just proximal to the distal femoral physis. The deformity was treated by an opening wedge osteotomy with lateral translation and external rotation of the distal epiphysis using a guide-wire technique; a corticocancellous allograft bridged the defect, which was stabilized with a 2.0-mm locking Y-plate designed for human phalangeal fractures. RESULTS: Successful deformity correction was obtained with subsequent healing of the osteotomy and maintained longitudinal bone growth. Sciatic neurapraxia developed as a result of a migrating adjunct pin (9 days post-operatively), which was removed. At long-term follow-up (4 years), a 12% shortening of the femur did result in addition to an asymptomatic grade 2 medial patellar luxation (MPL). The cause of the MPL was not evident; the owners declined treatment and the dog continued to function as an active hunting dog. CLINICAL SIGNIFICANCE: Prior to ossification of the epiphyses in very young animals, which precludes effective radiographic pre-planning, the guide-wire technique can be utilized as the primary tool for performing angular deformity correction. Adequate fixation and stabilization can be obtained with small human specialty locking plates.

Influence of radiographic techniques on the measurement of femoral anteversion angles and a conformation score of pelvic limbs in Labrador retrievers.

OBJECTIVE: To determine repeatability of and correlation between 2 radiographic measurements of femoral anteversion angles (FAA) and to determine their influence on a score derived from tibial plateau angle (TPA) and FAA to predict the risk of cranial cruciate ligament disease (CCLD). STUDY DESIGN: Prospective clinical study. ANIMALS: Forty-eight Labrador retrievers with or without CCLD. METHODS: FAA and CCLD scores were calculated for each limb from extended pelvic radiographs (t-FAA) or angled (a-FAA) projections of the femur by 3 investigators. One investigator repeated measurements twice. Data were analyzed for repeatability, correlation between t-FAA and a-FAA, and their influence on CCLD scores. RESULTS: FAA correlated most strongly with the distance between the femoral head and the femoral axis on mediolateral radiographs, a measurement with excellent repeatability. t-FAA and a-FAA correlated with each other (r > 0.79, P < .0001), although t-FAA were about 1° greater than a-FAA (P = .01). Intrainvestigator and interinvestigator repeatability of the CCLD score was fair when derived from t-FAA and good to excellent when derived from a-FAA. CCLD scores differed between radiographic techniques but led to different predictions in only 9 (10%) limbs, all with lower TPA and CCLD scores than the rest of the population. CONCLUSION: a-FAA correlated strongly with t-FAA and improved the repeatability of CCLD scores within and between investigators. CLINICAL SIGNIFICANCE: A craniocaudal angled beam projection of the femur is a suitable alternative to a ventrodorsal pelvic radiograph when measuring FAA and may improve the repeatability and positive predictive value of CCLD scores.

Factors contributing to the variability of a predictive score for cranial cruciate ligament deficiency in Labrador Retrievers.

BACKGROUND: We recently reported that a conformation score derived from the tibial plateau angle (TPA) and the femoral anteversion angle (FAA), best discriminates limbs predisposed to, or affected by cranial cruciate ligament disease (CCLD), from those that are at low risk for CCLD. The specificity and sensitivity of this score were high enough to support further investigations toward its use for large-scale screening of dogs by veterinarians. The next step, which is the objective of the current study, is to determine inter-observer variability of that CCLD score in a large population of Labrador Retrievers. A total of 167 Labradors were enrolled in this cross-sectional study. Limbs of normal dogs over 6 years of age with no history of CCLD were considered at low risk for CCLD. Limbs of dogs with CCLD were considered at high risk for CCLD. Tibial plateau and femoral anteversion angles were measured independently by two investigators to calculate a CCLD score for each limb. Kappa statistics were used to determine the extent of agreement between investigators. Pearson's correlation and intraclass coefficients were calculated to evaluate the correlation between investigators and the relative contribution of each measurement to the variability of the CCLD score. RESULTS: The correlation between CCLD scores calculated by investigators was good (correlation coefficient = 0.68 p < 0.0001). However, interobserver agreement with regards to the predicted status of limbs was fair (kappa value = 0.28), with 37% of limbs being assigned divergent classifications. Variations in CCLD scores correlated best with those of TPA, which was the least consistent parameter between investigators. Absolute interobserver differences were two times greater for FAAs (4.19° ± 3.15) than TPAs (2.23° ± 1.91). CONCLUSIONS: The reproducibility of the CCLD score between investigators is fair, justifying caution when interpreting individual scores. Future studies should focus on improving the reproducibility of TPA and FAA measurements, as strategies to improve the agreement between CCLD scores.

Distal femoral lateral closing wedge osteotomy as a component of comprehensive treatment of medial patellar luxation and distal femoral varus in dogs.

OBJECTIVE: To describe a cohort of dogs with medial patellar luxation managed with a distal femoral lateral closing wedge ostectomy (DFO) as a component of comprehensive treatment, and to report radiographic and long-term clinical outcome of this technique. METHODS: Medical records of dogs that had a lateral closing wedge DFO as part of management of medial patellar luxation at three veterinary teaching hospitals were reviewed. Surgical reports as well as the preoperative, postoperative, and follow-up radiographs were reviewed. The anatomical lateral distal femoral angle (aLDFA) was determined. Long-term clinical outcome was assessed by telephone interview with the owner. RESULTS: A lateral closing wedge DFO was performed on 66 limbs. The mean pre- and postoperative aLDFA was 107.6° ± 5.8° and 94.1° ± 4.2°, respectively. Cranial cruciate ligament disease was identified in 28/66 affected limbs. Tibial angular deformity, torsional deformity, or both was identified in nine of the 66 limbs. Ostectomy healing was confirmed radiographically in 51/66 limbs. The mean time to union was 73 ± 37 days. All patellae were in the normal position and stable. Complications included infection (2/51), fixation failure (1/51), delayed healing (2/51), and persistent lameness (1/51). CLINICAL SIGNIFICANCE: In this cohort of cases, DFO was a highly successful and repeatable component of surgical treatment for dogs with medial patellar luxation associated with femoral varus. This study also provides more evidence of the high rate of concurrent cranial cruciate ligament disease in cases of medial patellar luxation complicated by femoral varus, and supports an association between stifle instability and medial patellar luxation.

Evaluation of a scoring system based on conformation factors to predict cranial cruciate ligament disease in Labrador Retrievers.

OBJECTIVE: To determine the association of a radiographic score derived from tibial plateau angle (TPA) and femoral anteversion (FAA) with an outcome of cranial cruciate ligament deficiency (CCLD) in large dogs. STUDY DESIGN: Cross-sectional study. ANIMALS: 167 Labrador Retrievers. METHODS: Hind limbs of sound Labrador Retrievers over 6 years of age were considered at low risk for CCLD. Limbs were considered high risk for CCLD if they were affected or predisposed (sound contralateral limb in dogs with unilateral CCLD). The radiographic CCLD score was calculated for each limb. The TPA, FAA, and CCLD scores were compared between limbs of the same dog and between risk categories. A contingency table was used to evaluate the association of the CCLD score with the CCLD status of limbs. RESULTS: TPA, FAA, and CCLD scores were greater in limbs categorized as high risk for CCLD than in normal limbs. The sensitivity and specificity of the CCLD score was 87% and 79%, respectively. The positive predictive value was 69% and the negative predictive value was 92%. Scores were similar between paired right and left limbs, but did not agree for predicted status in 14/106 dogs. DISCUSSION: Our study supports an association between TPA, FAA, and CCLD in Labrador Retrievers. The negative predictive value of the CCLD score supports its application for screening dogs considered at low risk for CCLD. Positive CCLD scores should be interpreted with caution and the status of a dog may be undetermined if scores obtained on each limb disagree.

Combined tibial plateau levelling osteotomy and tibial tuberosity transposition for treatment of cranial cruciate ligament insufficiency with concomitant medial patellar luxation.

OBJECTIVES: To describe the surgical technique and report short-term outcome for combined tibial plateau levelling osteotomy and tibial tuberosity transposition (TPLO-TTT) as an option in the treatment of cranial cruciate ligament insufficiency with concomitant medial patellar luxation. METHODS: Medical records were reviewed (2011-2013) of dogs that underwent a standard tibial plateau levelling osteotomy followed by a tibial tuberosity transposition in the frontal plane and stabilized with pin and tension-band wire fixation as a component of surgical treatment for combined cranial cruciate ligament insufficiency and medial patellar luxation. Signalment, fixation method together with any ancillary procedures, function at the in-hospital follow-up examinations, and any complications were recorded. Healing was assessed retrospectively based on the grading criteria of the International Society Of Limb Salvage. RESULTS: Fifteen stifle joints in 11 dogs were identified; 13 stifles were available for in-hospital follow-up. All 13 achieved union (3 with grade III/IV and 10 with grade IV/IV radiographic healing scores); mean time to healing was 10.6 (± 2.9) weeks. Patellar ligament thickening was also identified radiographically in seven of the 13 of stifle joints. All dogs were reported to have mild or no lameness at their last follow-up examination. No catastrophic or major postoperative complications occurred that required additional surgery. Patellar re-luxation did not occur in any of the 13 stifles available for in-hospital follow-up. CLINICAL SIGNIFICANCE: The TPLO-TTT was found to be a reliable and effective technique when used as a part of the treatment of combined cranial cruciate ligament insufficiency with concomitant medial patellar luxation in this series of dogs.

Novel TPLO Alignment Jig/Saw Guide Reproduces Freehand and Ideal Osteotomy Positions.

OBJECTIVES: To evaluate the ability of an alignment jig/saw guide to reproduce appropriate osteotomy positions in the tibial plateau leveling osteotomy (TPLO) in the dog. METHODS: Lateral radiographs of 65 clinical TPLO procedures using an alignment jig and freehand osteotomy performed by experienced TPLO surgeons using a 24 mm radial saw blade between Dec 2005-Dec 2007 and Nov 2013-Nov 2015 were reviewed. The freehand osteotomy position was compared to potential osteotomy positions using the alignment jig/saw guide. The proximal and distal jig pin holes on postoperative radiographs were used to align the jig to the bone; saw guide position was selected to most closely match the osteotomy performed. The guide-to-osteotomy fit was categorized by the distance between the actual osteotomy and proposed saw guide osteotomy at its greatest offset (≤1 mm = excellent; ≤2 mm = good; ≤3 mm = satisfactory; >3 mm = poor). RESULTS: Sixty-four of 65 TPLO osteotomies could be matched satisfactorily by the saw guide. Proximal jig pin placement 3-4 mm from the joint surface and pin location in a craniocaudal plane on the proximal tibia were significantly associated with the guide-to-osteotomy fit (P = 0.021 and P = 0.047, respectively). CLINICAL SIGNIFICANCE: The alignment jig/saw guide can be used to reproduce appropriate freehand osteotomy position for TPLO. Furthermore, an ideal osteotomy position centered on the tibial intercondylar tubercles also is possible. Accurate placement of the proximal jig pin is a crucial step for correct positioning of the saw guide in either instance.

Complex angular and torsional deformities (distal femoral malunions). Preoperative planning using stereolithography and surgical correction with locking plate fixation in four dogs.

OBJECTIVE: To describe the surgical technique of complex distal femoral deformity correction with the aid of stereolithography apparatus (SLA) biomodels, stabilized with locking plate fixation. METHODS: Full-size replica epoxy bone biomodels of the affected femurs (4 dogs/ 5 limbs) were used as templates for surgical planning. A rehearsal procedure was performed on the biomodels aided by a guide wire technique and stabilized with locking plate fixation. Surgery performed in all dogs was guided by the rehearsal procedure. All pre-contoured implants were subsequently used in the definitive surgical procedure with minimal modification. RESULTS: All dogs had markedly improved, with near normal functional outcomes; all but one had a mild persistent lameness at the final in-hospital follow-up examination (mean: 54.4 weeks; range: 24-113 weeks after surgery). All femurs healed without complications (mean: 34 weeks, median: 12 weeks; range: 8-12 weeks for closing osteotomies, and 26-113 weeks for opening wedge osteotomies). Long-term follow-up examination (mean: 28.6 months; range: 5-42 months) revealed all but one owner to be highly satisfied with the outcome. Complications were observed in two dogs: prolonged tibiotarsal joint decreased flexion that resolved with physical therapy. In one of these dogs, iatrogenic transection of the long digital extensor tendon was repaired, and the other had a peroneal nerve neurapraxia. CLINICAL SIGNIFICANCE: Stereolithography apparatus biomodels and rehearsal surgery simplified the definitive surgical corrections of complex femoral malunions and resulted in good functional outcomes.

Severe Polyethylene Wear Requiring Revision Total Hip Arthroplasty in Three Dogs.

OBJECTIVE: To describe the occurrence of severe polyethylene wear of the acetabular component in 3 dogs that ultimately led to implant failure, and to report the outcome of revision of total hip arthroplasty (THA) in these cases. STUDY DESIGN: Case report ANIMALS: Dogs (n=3). RESULTS: Three dogs with hip dysplasia underwent routine THA before 2 years of age. All dogs became acutely lame 4-5 years after THA. Radiographs revealed acetabular cup wear in all cases, shell fragmentation in 2 cases, and additional stem failure in 1 case. All dogs underwent successful revision surgery, during which severe polyethylene wear and metallosis was observed. Revision surgery provided an excellent clinical outcome in all dogs from 10 months to 4 years post revision. CONCLUSION: Polyethylene wear and implant failure may be a significant long-term complication of THA not previously recognized, which may be especially true when placed at an early age in a large breed, active dog, or in a dog with significant morbidity associated with other limbs. A successful revision was achieved in all 3 dogs. Additional investigation is warranted to document the risk factors associated with severe polyethylene wear in canine THA.

SURGICAL CORRECTION OF A CERVICAL SPINAL FRACTURE IN A BENNETT'S WALLABY (MACROPUS RUFOGRISEUS).

Macropods are susceptible to trauma, and fractures of the cervical vertebrae due to collisions are relatively common. A 4-yr-old, intact male Bennett's wallaby (Macropus rufogriseus) was presented acutely nonambulatory and tetraparetic but with motor function present in all limbs. Cervical radiographs revealed a C4 vertebral fracture. Surgical stabilization was obtained through a ventral midline approach whereby the vertebral bodies were distracted and then secured with screws and polymethylmethacrylate (PMMA). Postoperative radiographs revealed restoration of the spinal canal and appropriate implant placement. The patient was discharged 4 days postoperatively and gradually recovered full neurologic function per the owner over the ensuing 10 wk. Subsequent radiographs obtained 10.5 mo postoperatively revealed a healed fracture with stable implants. The ventral spinal distraction and stabilization technique using screws and PMMA, as are used in the domestic dog, was successful in this wallaby despite its smaller vertebral size and comparable lack of soft-tissue support.

A comparative study of the dorsolateral and ventrolateral approaches for repair of canine sacroiliac luxation.

OBJECTIVES: Retrospective comparison of dorsolateral (DLA) and ventrolateral (VLA) surgical approaches for treatment of canine sacroiliac luxation using three different radiographic analyses. METHODS: Surgical cases with immediate and ≥4 week postoperative radiographs were reviewed (Jan. 2000 to Jan. 2015). Exactness of reduction, screw position, and sacral body screw purchase were assessed with three separate methods: single plane assessment and orthogonal assessment with or without rotational limits. RESULTS: The reduction index (RI) for DLA and VLA was not significantly different with single plane assessment (p = 0.0789), but it was significantly greater for DLA than VLA with orthogonal assessment, with or without rotational limits (p = 0.0039, p = 0.0146). No differences were observed with screw placement into the intended location (single plane, and orthogonal assessment with or without rotational limits; p = 0.2941, p = 0.4151, p = 0.3550, respectively). No differences were observed between mean screw purchase index (SPI) and the 60% goal for the DLA (p = 0.1303, p = 0.9594, p = 0.7120) or 50% goal for the VLA (p = 0.2224, p = 0.1401, p = 0.2224; single plane, and orthogonal assessment with or without rotational limits). Implant loosening was present in four DLA cases and one VLA case. No differences were observed in the number of cases or number of screws that loosened (p = 0.3483 and p = 0.6873, respectively). CLINICAL SIGNIFICANCE: The key factor demonstrated in maintaining screw and fixation stability was correct screw placement within the sacral body, regardless of the surgical approach.

Biomechanical comparison of pin and tension-band wire fixation with a prototype locking plate fixation in a transverse canine patellar fracture model.

OBJECTIVE: To compare a locking plate (LP) with pin and tension-band wire (pin/TBW) for fixation of mid-patellar transverse fractures. MATERIALS AND METHODS: Cadaveric canine stifle joints from 10 adult mixed breed dogs (23-36 kg) were used. Mid-patellar transverse osteotomies were randomly stabilized (in pairs) with either pin/TBW or a prototype LP. Cyclic loads (1 Hz, 500 cycles) at 100% body weight (90°-135° stifle joint extension), were applied. Survival or failure of constructs was defined as <2 mm fracture gap distraction at 500 cycles, or ≥2 mm fracture gap distraction at the number of cycles sustained, respectively. Number of cycles at failure and distraction gap were compared with a paired Student's t-test, and a survival analysis performed with a Mantel-Cox test. All constructs that survived cyclic testing were tested in single cycle load to failure (1.0 mm/sec; 110° stifle joint extension); yield strength was compared with a Wilcoxon rank sum test. Significance was set at p <0.05. RESULTS: All 10/10 LP and three out of 10 pin/TBW fixations survived cyclic testing. Survival analysis, number of cycles at failure, and distraction gap all were significantly different between the two groups (p = 0.0011, p = 0.0013, and p <0.0001, respectively). Construct yield strength was not significantly different (p = 0.1273). CONCLUSIONS: The failure mode with pin/TBW was consistently similar to failures observed clinically. The LP demonstrated consistent, reliable and stable fixation.