Treatment of Y-T Humeral Fractures with Polyaxial Locking Plate System (PAX) in 14 Dogs.

The aim of this study is to report the results and to review the outcome of 14 cases of Y-T humeral fractures repair using paired polyaxial locking system (PAX) plates through a combined medial and lateral approach. Fourteen consecutive dogs, with traumatic humeral Y-T fractures, met the inclusion criteria. This study includes signalment, preoperative radiographs, type of implants, radiographic bone healing assessment, complications, range of motion (ROM) of the elbow and limb function evaluated at 120 days after surgery. Postoperative radiographs revealed adequate anatomic reconstruction, and in all cases, bone healing has been achieved. No implant failure was observed. Functional outcome was excellent in 7 dogs (no lameness and preserved ROM), good in 4 (slight lameness and moderate ROM reduction) and discrete in 2 (mild lameness and severe ROM reduction). Complications were encountered in 2/14 patients with implant-associated infection resolved after long-term antibiotic treatment and implant removal. The PAX system is shown to be a valid alternative for the treatment of Y-T humeral fractures, offering the benefit of polyaxial insertion of locking screws. The possibility of angle locking screws is helpful in the distal humeral bicondylar fractures, providing additional options for screw placement in juxtarticular fractures, avoiding fracture lines or other implants.

Long-term outcome following synthetical reconstruction of the medial collateral tarsal ligament in a dog.

Background: Tibiotarsal instabilities caused by partial or complete rupture of the medial collateral tarsal ligament (MCTL) are commonly treated by arthrodesis techniques with poor functional results and significant complication rates. Case Description: This study describes a new surgical technique for synthetic reconstruction of the MCTL in an overweight dog (estimated body condition score 8/9) with an avulsion of the long head of the MCTL. Three bone tunnels were drilled in the distal tibia, the talus, and the central tarsal bone, thus respecting the anatomical insertions of the physiological ligament. An Ultra-High Molecular Weight Polyethylene (UHMWPE) implant was fixed with interference screws to reconstruct the long and short heads of the MCTL. Premature weight-bearing was reported at 2 weeks postoperatively following early removal of the flexible restraint (bivalve resin boot), which had initially been prescribed for 6 weeks. At 11 weeks postoperatively, the tibiotarsal joint showed good valgus stability and the dog's gait was subnormal. At 12 and 16 months postoperatively, the dog regained full function of the operated limb although no weight loss was initiated as recommended. Conclusion: The use of a UHMWPE implant fixed with interference screws to reconstruct the MCTL allowed a return to full function of the tibiotarsal joint, without complications despite an early return to weight-bearing without external restraint. The success of this isolated surgical technique could lead to improvements in the surgical management of MCTL rupture if these initial results are confirmed by a prospective study with a larger number of patients.

Comparison between Areas of Bone Visualization Using Radiolucent Hybrid Fixator Frames and Graphically Simulated Metallic Frames: An Ex Vivo Study.

The objective of this study is to evaluate the difference between the amount of bone visible with the superimposition of a radiolucent hybrid external fixator and a graphically simulated metallic frame. Eighteen frames were applied to eighteen bone specimens. The fracture area (FA), the radiolucent area (RLA) and the radiopaque area (ROA) inside the FA were calculated for each construct on both postoperative views. The ratio between the RLA and FA and between the ROA and FA was used to evaluate the amount of bone visible in the FA with a radiolucent and a radiopaque fixator, respectively. Finally, the areas of RLA and ROA were compared using the Wilcoxon test and Friedman test to evaluate the effect of the radiolucent material on the amount of bone visible. Differences were considered significant if p < 0.5. In every specimen p was <0.5. The amount of bone visible was significantly higher with the radiolucent frame compared to the radiopaque frame. Based on the results of this study, the use of radiolucent materials can be a valuable option for external fixation, in order to decrease the radiographic interference of the frame, allowing better assessment of fracture reduction and bone healing on postoperative radiographs.

Pelvic limb alignment measured by computed tomography in purebred English Bulldogs with medial patellar luxation.

OBJECTIVES: The aim of the study was to describe the differences in pelvic limb alignment between healthy purebred English Bulldogs and those with medial patellar luxation through the measurement of femoral and tibial angles on computed tomography images in multiplanar reconstruction modality (MPR-CT). METHODS: Twenty-one purebred English Bulldogs were included and divided into two groups: one including healthy dogs (15 limbs) and the other including those with medial patellar luxation (24 limbs). Three different observers used MPR-CT to measure the following angles: anatomical lateral proximal femoral angle (aLPFA), anatomical lateral distal femoral angle (aLDFA), mechanical lateral proximal femoral angle (mLPFA), mechanical lateral distal femoral angle (mLDFA), angle of inclination of the femoral neck (AI), angle of anteversion (AA), mechanical medial proximal tibial angle (mMPTA), mechanical medial distal tibial angle (mMDTA), mechanical caudal distal tibial angle (mCdDTA), mechanical caudal proximal tibial angle (mCdPTA), and the tibial torsion angle (TTA). A Mann-Whitney U test was used to compare each variable in both groups. RESULTS: The values for aLDFA and mLDFA in the medial patellar luxation population were significantly increased compared to healthy subjects (p <0.05). No significant differences were observed for the other variables. CLINICAL SIGNIFICANCE: In our population, an increased distal femoral varus was associated with medial patellar luxation. Our results could be useful to determine whether or not angular deformity of the femur is present and help determine the degree of correction necessary to restore alignment.

Single cycle to failure in bending of three titanium polyaxial locking plates.

OBJECTIVE: Evaluation of the bending properties in one direction of three titanium polyaxial locking plate systems. MATERIALS AND METHODS: The Polyaxial Advanced Locking System (PAX®) straight plate (PAX SP), the PAX® reconstruction plate (PAX RP), and the VetLOX reconstruction plates (VetLOX) were evaluated individually and as constructs applied to a bone model simulating a fracture gap and compared using a two-way analysis of variance and Tukey post-hoc analysis. RESULTS: The PAX SP had the highest values of bending stiffness, bending structural stiffness and bending strength. When tested as plates alone, the PAX RP and VetLOX showed no differences with regard to bending stiffness and bending structural stiffness, whilst the PAX RP had significantly higher strength. The PAX RP construct had significantly higher bending stiffness, bending structural stiffness and bending strength than the VetLOX construct. CLINICAL RELEVANCE: The PAX RP and VetLOX reconstruction plates are much more likely to fail when used as bridging implants, thus adjunct support is needed. The lower bending strength of the VetLOX reconstruction plates suggests it should not be used in fractures under high loads.

Bovine herpesvirus 4 based vector interaction with liver cells in vitro and in vivo.

Gene transfer into hepatocytes is highly desirable for the long-term goal of replacing deficient proteins and correcting metabolic disorders. Bovine herpesvirus 4 (BoHV-4) based vector capability to transduce rat liver cells in vitro and in vivo was assessed. For the in vitro study, a buffalo rat liver cell line was successfully transduced by BoHV-4 and although did not show toxicity, the immediate early two viral gene was transcribed and cells harboring the intact viral genome could be pharmacologically selected, but no viral replication took place. For the in vivo study, adult male rats were inoculated intraportally and intraparenchimally with a BoHV-4 expressing enhanced green fluorescent protein and liver sections were analyzed through fluorescent microscopy. Although the liver parenchyma could not be transduced, the endothelial layer of the liver vasculature showed a robust transgene expression without toxicity. Successful BoHV-4 based vector transduction of primary cultures of rat hepatocytes suggests that extrinsic factors, and not hepatocytes per se, are the cause of such lack of transducibility. The present study serves as a starting point for study of the use of BoHV-4 based vectors to target gene delivery to vascular endothelial cells.