The Effect of Location of a Unicortical Defect on the Mechanical Properties of Rabbit Tibiae: A Model of the Distal Jig Pin Hole in Tibial Plateau Levelling Osteotomy.

OBJECTIVE: The aim of this study was to determine the effect of a unicortical defect at either the mid-diaphysis (MD) or distal metaphysis (DM) on the torsional properties of tibiae in an in vitro rabbit model, and to further examine optimal distal jig pin position for the canine tibial plateau levelling osteotomy (TPLO) procedure. STUDY DESIGN: Thirty-eight tibiae from 19 skeletally mature female New Zealand White rabbits were assigned to one of three groups; Group 1: intact, Group 2: MD defect and Group 3: DM defect. Defects were created using a 1.6 mm Ellis pin. Pure torsion was applied to each sample and peak torque and angular displacement recorded. RESULTS: All tibiae fractured in a spiral configuration. Fracture lines involved the defect in 33% of the MD samples and 0% of the DM samples. No differences were detected for peak torque and stiffness between groups. However, energy (mean ± standard deviation) was significantly reduced (p = 0.028) in the MD group (0.18 ± 0.07) relative to the intact tibia group (0.31 ± 0.14). Angle was also significantly reduced (p = 0.040) in the MD group (0.17 ± 0.05) compared with the intact group (0.23 ± 0.07). Placement of a DM defect had no significant effect on mechanical properties of the rabbit tibiae. CONCLUSION: Defects placed in the MD significantly reduced energy and angle in comparison to intact samples. No significant difference in peak torque or stiffness was observed between groups. If canine tibiae were similarly affected, our findings suggest jig pin placement in the DM to have a lesser effect on the torsional properties of the tibiae.

Effect of ultraviolet-C light on the environmental bacterial bioburden in various veterinary facilities.

OBJECTIVE: To determine the effect of a mobile UV-C disinfection device on the environmental bacterial bioburden in veterinary facilities. SAMPLES: 40 swab samples of surfaces from the operating theaters of 3 veterinary hospitals and 1 necropsy laboratory. PROCEDURES: Various surfaces were swabbed, and collected material was eluted from the swabs in PBSS. Then, an aliquot of the sample fluid was processed with a bacteria-specific rapid metabolic assay to quantify bacterial bioburden. Each site was then treated with UV-C light with an automated disinfection device for approximately 45 minutes. The same surfaces were swabbed following UV-C treatment, and bioburden was quantified. The bioburden at additional time points, including after a second UV-C treatment, was determined for the small animal operating theater. RESULTS: All surfaces at all sites had a persistent viable bacterial population following manual cleaning. Disinfection with UV-C achieved a mean bioburden reduction of 94% (SD, 5.2%; range, 91% to 95%) for all surfaces, compared with manual disinfection alone. Repeated UV-C treatment of the small animal operating theater reduced mean bioburden by 99% (SD, 0.8%), including no detectable bacteria on 4 of 10 surfaces. CONCLUSIONS AND CLINICAL RELEVANCE: Disinfection with UV-C light may be a beneficial adjunct method for terminal disinfection of veterinary operating theaters to reduce environmental bioburden. (Am J Vet Res 2021;82:582-588).

Single level posterolateral lumbar fusion in a New Zealand White rabbit (Oryctolagus cuniculus) model: Surgical anatomy, operative technique, autograft fusion rates, and perioperative care.

INTRODUCTION: The posterolateral lumbar fusion (PLF) New Zealand White (NZW) (Oryctolagus cuniculus) rabbit model is a long-standing surgical technique for the preclinical evaluation of materials for spinal fusion. A detailed understanding of lumbar spine anatomy and perioperative care requirements of rabbits is imperative for correct execution of the model both scientifically and ethically. This study describes the preoperative procedures and surgical techniques used in single level PLF in a NZW rabbit model as it pertains to the animal husbandry, lumbar spine anatomy, anesthesia, surgical approach, and perioperative care of rabbits in a research setting. MATERIALS AND METHODS: We describe the surgical technique and perioperative patient care for single level PLF in a NZW rabbit model. Medical records from a single research facility were retrospectively reviewed for adult NZW rabbits that underwent single level PLF (L4-L5) between January 2016 and December 2019. The number of lumbar vertebrae per rabbit, fusion rates at 12 weeks using iliac crest autograft and complications are reported. Skeletal maturity was confirmed by preoperative fluoroscopic and radiographic documented closure of hindlimb physes. RESULTS: The PLF rabbit surgical model and perioperative patient care is described. PLF was performed in 868 adult female entire NZW rabbits. The majority of rabbits had seven lumbar vertebrae (620/868; 71.4%), followed by six (221/868; 25.5%), and eight (27/868; 3.1%). Fusion rates at 12 weeks for PLF using iliac crest autograft as assessed by manual palpation and radiographic assessment was 76.9% and 70.0%, respectively. Postoperative complications included occasional partial autograft site wound dehiscence due to self-trauma. CONCLUSIONS: For PLF rabbit models, a detailed understanding of the surgical technique, rabbit lumbar anatomy including number of lumbar vertebrae, and dietary and husbandry requirements of rabbits, is essential for execution of the model and animal welfare.

Kinematics of the Feline Antebrachiocarpal Joint from Supination to Pronation.

OBJECTIVE: Cats rely on their forelimb mobility for everyday activities including climbing and grooming. Supination and pronation of the forelimb in cats are considered to primarily involve the antebrachium, rather than the carpus. Therefore, our null hypothesis was that there would be no movement of the carpal bones (radial carpal bone, ulnar carpal bone and accessory carpal bone) relative to the ulna during supination and pronation. STUDY DESIGN: Eight feline cadaveric forelimbs were rotated from supination to pronation in a jig and computed tomography was performed in the neutral, supinated and pronated positions. The individual carpal bones were segmented from computed tomography images of the supinated and pronated scans in each of the eight specimens. A feline ulna coordinate system was established and used to quantify the translations and rotations between bones of the proximal carpal row and antebrachium. RESULTS: After the carpus was rotated from the initial supinated position into pronation, there was significant translation (x, y and z axes) and rotation (x and y axes) of the proximal row of carpal bones based on absolute magnitude values. Given the differences in translations and rotations of the proximal row of carpal bones, our null hypothesis was rejected. CONCLUSION: The proximal row of carpal bones translate and rotate independently from the ulna in the cat during pronation of the antebrachium. This may have future implications in the diagnosis and management of feline carpal injuries involving the antebrachiocarpal joint.

Successful tracheoscopy-assisted reconstruction of traumatic tracheal avulsion in a cat.

OBJECTIVE: To outline the clinical findings, surgical management, complications, and outcomes in a case of intrathoracic, traumatic, tracheal avulsion. CASE SUMMARY: A 2-year-old domestic shorthair cat presented with respiratory distress 18 days after a motor vehicle accident. A tracheal avulsion was diagnosed and treated by surgical anastomosis. The initial anastomosis failed. The subsequent tracheoscopic-assisted tracheal anastomosis was successful. The cat had no further episodes of respiratory distress following the second surgery in a 9-month follow-up period. UNIQUE INFORMATION PROVIDED: This communication describes a complication of intrathoracic, traumatic, tracheal avulsion repair that has not previously been described and the use of tracheoscopy during the subsequent surgical procedure to ensure accurate suture placement.

A Retrospective Study Using the String of Pearls Tibial Plateau Levelling Osteotomy Locking Plate for the Treatment of Cranial Cruciate Ligament Disease.

OBJECTIVE: The aim of this study was to describe the use of String of Pearls (SOP) tibial plateau levelling osteotomy (TPLO) locking plates for the treatment of cranial cruciate ligament disease and retrospectively assess osteotomy healing, tibial plateau angle (TPA) change (c) and overall complication rates. METHODS: Medical records and radiographic studies of 170 SOP TPLO surgical procedures were analysed. Radiographic measurement of TPAc and osteotomy union was determined 6 to 8 weeks postoperatively. Intra- and postoperative major and minor complications were identified. Factors influencing TPAc, osteotomy union and complications were assessed. RESULTS: Mean (standard deviation) TPAc was 1.3° (1.61) and median osteotomy union was graded as 2 (26-50%) union. Improved osteotomy union was associated with retention of the antirotational pin (odds ratio [OR]: 2.3; 95% confidence interval [CI]: 1.3-4; p = 0.005) and reduced TPAc (OR: 0.8; 95%CI: 0.66-0.97; p = 0.02). Complications occurred in 42 (24.7%) procedures with 11 (6.5%) considered major and 31 (18.2%) minor. CLINICAL SIGNIFICANCE: The use of the SOP TPLO plating system resulted in a median grade 2 (26-50%) radiographic osteotomy union score at 6 to 8 weeks' follow-up, less than previous TPLO locking plate studies. Osteotomy union was associated with retention of the antirotational pin and reduced TPAc. Major and minor complication rates were marginally greater than recent locking plate studies with fibular fracture and screw loosening common complications. The use of SOP TPLO plates is cautioned and further study is warranted.

Three-dimensional kinematics of the canine carpal bones imaged with computed tomography after ex vivo axial limb loading and palmar ligament transection.

OBJECTIVE: To describe normal antebrachiocarpal joint kinematic motion during axial loading and to describe the effect of palmar radiocarpal ligament (PRL) and palmar ulnocarpal ligament (PUL) transection on this motion. SAMPLE POPULATION: Ten forelimbs from 5 adult greyhound cadavers. METHODS: Limbs were placed in a custom jig and computed tomography images of limbs were obtained in neutral and extended positions. The translation and rotation of the intermedioradiocarpal bone (RCB), ulnar carpal bone, and accessory carpal bone were described relative to the radius through rigid body motion analysis. Kinematic and load analysis was repeated after sequential transection of the PRL and the PUL. RESULTS: Sagittal plane extension with a lesser component of valgus motion was found in all evaluated carpal bones. RCB supination was also detected during extension. Compared with the normal intact limb, transection of either or both the PRL and the PUL did not influence mean translation or rotation data or limb load. However, the transection of the PRL and the PUL increased the variance in rotation data compared with intact limb. CONCLUSION: This study describes normal antebrachiocarpal kinematics as a foundation for determining carpal functional units. During axial loading, the PRL and the PUL may function to guide consistent motion in extension and flexion as well as pronation and supination. CLINICAL SIGNIFICANCE: Three-dimensional carpal kinematic analyses may improve our understanding of carpal injury and facilitate the development of novel treatments techniques.

Accuracy of tibial osteotomy placement using 2 different tibial plateau leveling osteotomy jigs.

OBJECTIVE: To report the accuracy of osteotomy position in dogs undergoing tibial plateau leveling osteotomy (TPLO) and to evaluate the effect of 2 different TPLO jig and saw systems on tibial osteotomy position. STUDY DESIGN: Retrospective case series. ANIMALS: Dogs (n = 124; 134 TPLO). METHODS: Medical records (2004-2005; 2008-2011) and stifle radiographs of 2 groups of dogs that had TPLO to treat cranial cruciate ligament disease were reviewed. One group had a TPLO performed using an alignment jig system alone (Slocum group), whilst in the other group, an alignment jig system combined with a saw guide (Synthes group) was used. Postoperative radiographs were examined and the distance and direction of the centroid of the osteotomy was compared to the intended osteotomy position. RESULTS: The absolute distance of eccentricity (DOE) in the Slocum group (5.6 ± 2.5 mm) was significantly greater than that of the Synthes group (3.4 ± 1.8 mm; P < .01). DOE was caudal and distal in 79% of cases. CONCLUSIONS: Most tibial osteotomies were centered at a point distal and caudal to the intended osteotomy position. Use of a TPLO system with a saw guide was associated with more accurate placement of the osteotomy and more accurate leveling of the tibial plateau.