Hydrated Nucleus Pulposus Extrusion in Dogs: Thoracolumbar Compared to Cervical Cases

Objective The aim of this study was to review and describe cases of thoracolumbar (TL) hydrated nucleus pulposus extrusion (HNPE) diagnosed with magnetic resonance imaging and surgery, and compare them to cases of cervical (C) HNPE. Study Design Retrospective, single-center study. Results Thirty-six dogs met the inclusion criteria. Fifteen cases were C and 21 TL. Thirteen dogs were chondrodystrophic breeds, mean body weight was 13 kg, median age was 7.5 years, and 30/36 were male. Fewer dogs were chondrodystrophic in the C group compared with the TL group (p = 0.022). More than 90% had an acute onset, and strong activity was more often reported in the TL group. TL HNPE was more often painful, and extruded disc material more often lateralized (p = 0.017). Median Modified Frankel Score at presentation was 3 and 72.2% were non-ambulatory. More TL HNPE (11/21) were treated surgically compared with C HNPE (4/15). Treatment choice was correlated with spinal cord compression (p = 0.0075). Median Modified Frankel Score improved during hospitalization (p = 0.002) and there was no difference in outcome between C and TL HNPE or conservative and surgical treatment. Mean follow-up time was 33 days. All patients were ambulatory at follow-up. Conclusion This study suggests that the HNPE is not limited to the C vertebral column of dogs and can occur in the TL vertebral column as well. Dogs with TL HNPE show spinal hyperesthesia more often and extruded nucleus material is more often lateralized. Outcome is similar to what has previously been described for C HNPE.

Visibility of Transcondylar Screw Fractures in Standard and Extended Scale Computed Tomography Images

Objective Application of extended computed tomography scale (ECTS) reconstruction to diagnose metal implant failure has been described in a single case report. The purpose of this study was to compare the features and visibility of humeral transcondylar screw fractures in standard CT scale (SCTS) and ECTS images. Study Design Case series: CT images of dogs with fractured transcondylar screws were retrospectively reviewed and described in both SCTS and ECTS images. Results Five dogs with a total of six transcondylar screw failures (five right and one bilateral) were reviewed. All cases had an ongoing humeral intercondylar fissure with varying degrees of stress remodelling. The fracture was seen in all screws on ECTS images, however only in three implants on SCTS images. The measured fracture gap was larger in ECTS images in all cases (range: + 0.14 mm to + 0.28mm). The three smallest fracture gaps were not seen on SCTS images. A subtle hypoattenuating streak (artefact) was visible adjacent to the screw fracture in 5/6 of cases using SCTS images. All screw fractures occurred parallel and often slightly medial to the humeral intercondylar fissure. Conclusion Implant failure is only seen with larger fracture gaps in SCTS images, with 3/6 screw fractures not visible in SCTS compared with ECTS. A hypoattenuating streak extending perpendicular to the implant in SCTS images is suggestive of screw fracture even if this is not directly visible.

Evaluation of Hindlimb Deformity and Posture in Dogs with Grade 2 Medial Patellar Luxation during Awake Computed Tomography Imaging while Standing

Objective The aim of this study was to determine the degree of bone deformities and hindlimb postural abnormalities in a standing position in awake Toy poodles with and without grade 2 medial patellar luxation (MPL) using high speed 320-row computed tomography (CT). Methods The limbs with grade 2 MPL (MPL-G2 group) and without any orthopaedic disorders (control group) were imaged in a standing position, without sedation or anaesthesia, using CT. In MPL-G2 group, images were obtained when the patella was luxated (G2-L group) and reduced (non-luxation, G2-NL group). Bone morphologies of the femur and tibia were quantified three-dimensionally. Hindlimb standing posture was evaluated by measuring femoral rotation and abduction angles, tibial rotation angle, metatarsal rotation angle, foot rotation angle, angle between the femoral anatomical axis and the mechanical axis of hindlimb and stifle joint line convergence angle. Results There were no significant differences in bone morphologic parameters between the MPL-G2 group (5 limbs) and the control group (6 limbs). In the G2-NL group, there were no significant hindlimb postural abnormalities. In contrast, in the G2-L group, significant hindlimb postural abnormalities including external rotation of femur, internal rotation of tibia and foot, external rotation of tarsal joint, large stifle joint convergence angle, genu varum and toe-in standing were observed. Conclusion Dogs with grade 2 MPL have no bone deformities but show abnormal standing posture when the patella is luxated.

Outcomes and Complications Associated with Acute Gunshot Fractures in Cats and Dogs

Objective The aim of this study was to summarize outcomes and complications of gunshot fracture management in small animals. Study Design Review of cats and dogs with radiographically confirmed acute gunshot fractures, presenting data on signalment, fracture location, fracture management (surgical vs. non-surgical, type of surgical repair), fracture comminution, extent of soft tissue trauma, postoperative complication and overall outcome. A poor outcome was defined as patient death, major postoperative complication or limb amputation (both as primary treatment or secondary to postoperative complications). Results Ninety-seven animals with 137 acute gunshot-induced fractures were identified. There were 21 (15.3%) maxillofacial, 16 (11.7%) vertebral column, 8 (5.8%) rib, 56 (40.9%) distal long bone (below stifle/cubital joint) and 36 (26.3%) proximal long bone (at or above stifle/cubital joint) fractures. Overall, 20/37 cases with sufficient follow-up details incurred a poor fracture outcome. Extensive soft tissue trauma at the fracture site was associated with an increased likelihood of poor outcome. The most common poor outcomes were primary limb amputations (7 cases) and postoperative complications (3 osteomyelitis/surgical site infections, 4 delayed/non-unions). Conclusions Gunshot fractures overall have high likelihood of poor outcome. Severe soft tissue injury is associated with complications. Mitigating poor outcome likely requires early aggressive wound management.

Computed Tomographic Evaluation of the Accuracy of Minimally Invasive Sacroiliac Screw Fixation in Cats

Objectives The aim of this study was to report the use of computed tomography (CT) for postoperative evaluation of the accuracy of sacroiliac reduction and minimally invasive screw fixation in a series of five cats. Materials and Methods Medical records between January 2016 and March 2017 of cats presenting to the author's institution were reviewed. Included were cats that had undergone minimally invasive sacroiliac screw fixation with a complete medical record and pre- and postoperative radiographs. Screw size was obtained from the medical records. CT images were acquired prospectively and evaluated to assess joint reduction, relative screw size and screw positioning. Results Six sacroiliac luxations and 6 screws were available. Fixation was achieved with either a 2.4 (n = 1) or 2.7 mm (n = 5), 316L stainless steel, cortical bone screw. Mean screw size as a proportion of sacral diameter was 47.7%. Sacroiliac reduction >90% in the craniocaudal plane and sacral screw purchase >60% of the sacral width were achieved in 3/5 cases. Mean dorsoventral screw angulation was 1.6 degrees (range: −9.7 to 11.7 degrees) and craniocaudal angulation was −4.5 degrees (range: −16.6 to 6.6 degrees). Complications included screw loosening in the one case of bilateral repair and penetration of the neural canal in one case which was not detected with postoperative radiographic evaluation. Clinical Significance CT evaluation provides a useful method for the assessment of sacroiliac reduction and the accuracy of screw placement.

Hemiepiphysiodesis for the Correction of Distal Femoral Valgus in Growing Dogs

Objectives The aim of this study was to describe hemiepiphysiodesis for the treatment of distal femoral valgus in immature dogs and to evaluate its effect on the anatomical lateral distal femoral angle (aLDFA). Methods Skeletally immature dogs with distal femoral valgus deformities that had undergone hemiepiphysiodesis between November 2012 and March 2020 at two private veterinary practices were included. Criteria for inclusion in the study were a preoperative aLDFA below the previously published reference range (94 ± 3.3 degrees) and radiographs of the femur taken preoperatively and at growth plate closure. Results A total of 11 dogs fulfilled the inclusion criteria, and a total of 17 limbs were treated. The mean aLDFA was 82.1 ± 3.2 degrees (range: 76–87 degrees) preoperatively and 93.1 ± 5 degrees (range: 76–99 degrees) at the final re-evaluation. The mean difference between the preoperative and final aLDFA was +11 degrees, which was significant. Undercorrection occurred in 2/17 cases, whereas overcorrection was not recorded. The implants were removed in 12/17 cases, and rebound growth occurred in 3 of these. Clinical Significance Hemiepiphysiodesis for the treatment of distal femoral valgus is a technique that allows for increase in aLDFA and should be considered as an early treatment in affected immature dogs. Monitoring for possible overcorrection using serial radiography is important. Implant removal when the desired aLDFA has been achieved is recommended because the incidence of rebound growth is uncommon in dogs.

Evaluation of Meniscal Load and Load Distribution in the Canine Stifle after Tibial Plateau Levelling Osteotomy with Postoperative Tibia Plateau Angles of 6 and 1 Degrees

Objectives The aim of the study was to investigate the kinetic and kinematic changes in the stifle after a tibial plateau levelling osteotomy (TPLO) with a postoperative tibia plateau angle (TPA) of either 6 or 1 degrees. Study Design Biomechanical ex vivo study using seven unpaired canine cadaver hindlimbs from adult Retrievers.Hinge plates were applied and a sham TPLO surgery was performed. Motion sensors were fixed to the tibia and the femur for kinematic data acquisition. Pressure mapping sensors were placed between femur and both menisci. Thirty per cent bodyweight was applied to the limbs with the stifle in 135 degrees of extension. Each knee was tested with intact cranial cruciate ligament (CCL), deficient CCL, 6 degrees TPLO and 1degree TPLO. Results Transection of the CCL altered kinematics and kinetics. However, comparing the intact with both TPLO set-ups, no changes in kinematics were detected. After 1 degree TPLO, a significant reduction in the force acting on both menisci was detected (p = 0.006). Conclusions Tibial plateau levelling osteotomy restores stifle kinematics and meniscal kinetics after transection of the CCL ex vivo. The contact force on both menisci is reduced significantly after TPLO with a TPA of 1 degree. Increased stifle flexion might lead to caudal tibial motion.

Compensatory Changes in Ground Reaction Forces in Small and Large Breed Dogs with Unilateral Hindlimb Lameness in Comparison to Healthy Dogs

Objective The aim of this study was to investigate whether small- to medium-sized dogs with a naturally occurring unilateral hindlimb lameness show the same compensatory changes in ground reaction forces as large-breed dogs and how the changes are displayed compared with healthy small- to medium-sized dogs. Study Design Small- to medium-sized dogs (n = 15) and large-breed dogs (n = 16) with unilateral rupture of the cranial cruciate ligament were examined. The kinetic parameters peak vertical force and vertical impulse of the two groups were compared with each other and compared with healthy Beagles (n = 15) and with healthy Labrador Retrievers (n = 17), respectively. Results The healthy Beagle group showed a significantly higher weight loading on the forelimbs compared with the healthy Labrador group. The affected groups in comparison with the corresponding healthy groups showed a higher load on the non-affected body half and a significant lower weight bearing on the affected limb. Comparing the two affected groups, no significant difference could be found. Conclusion Despite a substantially different initial situation regarding weight distribution of the examined small- to medium-sized dogs and large dogs, a unilateral hindlimb lameness leads to the same compensatory changes (cranial and lateral shift of the body mass centre).