Development and in situ application of an adjustable aiming device to guide extra- to intraarticular tibial tunnel drilling for the insertion of the cranial cruciate ligament in dogs.

OBJECTIVE: To develop and test an arthroscopic aiming device for extra- to intraarticular tibial tunnel drilling emerging at the center of the tibial insertion (CenterTib) of the cranial cruciate ligament (CCL) in medium to large breed dogs. STUDY DESIGN: Descriptive experimental study. SAMPLE POPULATION: Fifty-two cadaveric hind limbs of dogs >or=20 kg BW. METHODS: The mediolateral position and craniocaudal position (ccPos) of CenterTib in relation to the caudomedial meniscotibial ligament were measured on photographs of 46 dissected tibial plateaus. The proximal tibial depth (TibDepth) was determined on lateral radiographs and its correlation with ccPos was assessed using linear regression analysis. Extra- to intraarticular arthroscopic tibial tunnel drilling was performed in 6 independent cadaveric stifles. A C-guide with an adjustable craniocaudal offset was constructed and adjusted according to ccPos estimated based on TibDepth. The position of the resulting bone tunnels was compared with the position of the CenterTib. RESULTS: Pearson's correlation between TibDepth and ccPos was strong (R=0.86; P<.001). ccPos (y) as a function of TibDepth (x) can be expressed as y=-4.8+0.3x. Arthroscopic tunnel drilling resulted in a median deviation of the drill tunnels around the CenterTib of 1 mm. CONCLUSION: The regression equation and aiming device permit localization and targeting of CenterTib during extra- to intraarticular tibial bone tunnel drilling in vitro. CLINICAL RELEVANCE: The proposed technique may reduce tibial tunnel misplacement when performing intraarticular CCL repair using a tibial bone tunnel.

Effects of attachment sites and joint angle at the time of lateral suture fixation on tension in the suture for stabilization of the cranial cruciate ligament deficient stifle in dogs.

OBJECTIVE: To investigate the influence of different sites of lateral suture fixation for stabilization of the cranial cruciate ligament (CCL) deficient stifle and different joint angles at time of tightening on suture tension. STUDY DESIGN: Controlled laboratory study. SAMPLE POPULATION: Stifle joints (n=9) of dogs >or=20 kg. METHODS: After CCL transection, each stifle was stabilized using 12 combinations of 4 different methods of lateral suture stabilization (LSS) and 3 different joint angles at time of suture tightening. Load within the suture throughout a full range of passive motion (ROM) was measured for each combination using a custom made load cell. RESULTS: All 4 LSS methods had an increase in suture tension on stifle flexion. LSS with the suture looped around the lateral fabella and secured to the proximal aspect of the tibia through 2 parallel drill holes at the tibial crest had the least change in suture tension during ROM. Tightening the suture at 70 degrees joint angle resulted in a significant loss of suture tension on extension. CONCLUSIONS: None of the LSS resulted in constant suture tension, questioning current recommendations regarding "isometric" points for lateral suture fixation. Tightening the suture with the stifle held in flexion may result in joint instability on extension. CLINICAL RELEVANCE: LSS as commonly performed is associated with a significant increase in suture tension on flexion of the stifle, potentially over-constraining the joint. Tightening should be performed with the stifle in slight extension rather than in flexion.

Computer simulation of the distal aspect of the femur for assessment of donor core size and surface curvature for autologous osteochondral transplantation in the canine stifle joint.

OBJECTIVE: To report topographic matching of selected donor sites and donor core sizes for congruous reconstruction of the weight-bearing aspect of the femoral condyles in dogs for autologous osteochondral transplantation (AOT) using computer simulation. STUDY DESIGN: Computer simulation. SAMPLE POPULATION: Computed tomographic scans of the distal aspect of 1 femur from each of 6 mature dogs (>20 kg). METHODS: Three-dimensional surface models of the distal femora were constructed for virtual AOT. Different donor sites (n=15) within and outside the femoropatellar joint and 5 transplant sizes (diameters 3.5, 4.5, 6.0, 8.0, and 10.0 mm) were analyzed with respect to their topographic match with the articular surface of both femoral condyles. RESULTS: Transplants from the proximal abaxial aspect of the medial condyle and from the abaxial aspects of the medial and lateral trochlear ridges were the best topographic match. Mismatch increased linearly with increasing core diameter. Small core diameters (3.5 mm, 4.5 mm) from within the femoropatellar joint allowed restoration of surface contour at both femoral condyles similar to large core diameters (6 mm, 8 mm) from outside the femoropatellar joint. CONCLUSIONS: Based on this computer simulation, large core diameters should only be harvested from convex donor sites outside the femoropatellar joint, whereas transplants from the concave, axial aspects of the trochlear ridges may result in similar topographic match provided they are of small diameter. CLINICAL RELEVANCE: The abaxial aspect of the medial trochlear ridge and the proximal aspect of the medial femoral condyle appear to be the preferred AOT donor sites.

Mapping subchondral bone density of selected donor and recipient sites for autologous osteochondral transplantation in the canine stifle joint using computed tomographic osteoabsorptiometry.

OBJECTIVE: To characterize donor and recipient sites for autologous osteochondral transplantation (AOT) in the canine stifle joint with respect to maximal subchondral bone density (mSBD). STUDY DESIGN: Descriptive laboratory study. SAMPLE POPULATION: Femora (n=15) of dogs (>20 kg). METHODS: mSBD at selected donor sites within and outside the femoropatellar joint and at potential recipient sites for both femoral condyles was assessed using nonvolumetric computed tomographic osteoabsorptiometry and normalized to values obtained at the central weight-bearing aspect of the lateral femoral condyle. RESULTS: Only transplants harvested at the axial aspects of the lateral and medial trochlear ridge had a normalized mSBD comparable with the lateral and medial femoral condyle. Grafts from outside the femoropatellar joint, at the most proximal aspect of the medial femoral condyle and at the most distal aspect of the trochlea (the notch area) had mSBD values 13.8-24.4% less than at the femoral condyles. CONCLUSIONS: Choosing between donor sites within or outside the femoropatellar joint may significantly affect subchondral bone quality of harvested transplants. CLINICAL RELEVANCE: Donor sites abaxial to the femoropatellar joint and at the most proximal aspect of the medial femoral condyle may provide transplants of suboptimal bone morphology, challenging their use as primary donor sites for AOT in dogs. However, this statement is based on nonvolumetric assessment of bone density, necessitating verification using volumetric density analysis to finally infer the biomechanical value of different grafts.

Value of low-field magnetic resonance imaging in diagnosing meniscal tears in the canine stifle: a prospective study evaluating sensitivity and specificity in naturally occurring cranial cruciate ligament deficiency with arthroscopy as the gold standard.

OBJECTIVE: To evaluate the sensitivity and specificity of low-field magnetic resonance imaging (lfMRI) for detection of meniscal tears in the canine stifle. STUDY DESIGN: Double-blinded prospective clinical study. ANIMALS: Forty-two consecutive stifles of dogs (>or=20 kg; n=34) with clinical and radiologic signs suspicious for cranial cruciate ligament (CCL) insufficiency. METHODS: Each stifle had 7 predefined lfMRI sequences using a 0.5 T magnet with a human knee coil. After lfMRI, diagnostic arthroscopy was performed by 1 surgeon unaware of the MRI findings. After completion of the study MRI images were read by 1 investigator, unaware of the intraoperative findings. RESULTS: At arthroscopy, 22 stifles had meniscal tears requiring subtotal meniscectomy. Of these only 14 were identified by lfMRI. Overall sensitivity and specificity of lfMRI for detection of meniscal tears were 0.64 (95% confidence interval [95% CI]=0.43, 0.80) and 0.90 (95% CI=0.70, 0.97), respectively. Positive and negative predictive values were 0.88 (95% CI=0.64, 0.97) and 0.69 (95% CI=0.50, 0.83), respectively. Neither the state of dislocation of vertical longitudinal tears nor the amount of CCL rupture had an influence on lfMRI accuracy (P=1.00). CONCLUSION: lfMRI was of low diagnostic accuracy in detecting meniscal tears, when compared with arthroscopy. Especially negative lfMRI findings should be interpreted with caution. CLINICAL RELEVANCE: When using lfMRI as a noninvasive preoperative screening tool for the diagnosis of meniscal tears, a high percentage of missed meniscal tears has to be expected.

Mapping of split-line pattern and cartilage thickness of selected donor and recipient sites for autologous osteochondral transplantation in the canine stifle joint.

OBJECTIVE: To characterize donor and recipient sites for autologous osteochondral transplantation in the canine stifle joint with respect to split-line pattern and cartilage thickness. STUDY DESIGN: In vitro study. Sample Population- Stifle joints (n=30) of dogs >20 kg. METHODS: Collagen network orientation of the hyaline cartilage coverage of the distal femur was assessed using split-line technique (n=10). Cartilage thickness was measured radiographically on osteochondral plugs harvested at the abaxial and axial surfaces of the femoropatellar joint (n=15), the most proximal abaxial aspect of the medial condyle (CO; n=5) and at both femoral condyles (n=15). RESULTS: Cartilage within the femoropatellar joint and both femoral condyles had mostly transversely orientated pattern of split-lines. Abaxial to the femoropatellar joint split-lines were absent. All donor sites had significantly thinner cartilage than the medial condyle (CM). Only the distal trochlea had cartilage thickness comparable to the lateral condyle (CL). The thinnest cartilage was found abaxial to the femoropatellar joint followed by CO, which was approximately 2-3 times thinner than the cartilage at both condyles. CONCLUSIONS: None of the investigated donor sites provided transplants of comparable cartilage thickness to CM. Transplants from within the femoropatellar joint should be harvested in priority as they reach cartilage morphology comparable to CL. CLINICAL RELEVANCE: Adjusting for cartilage thickness and split-line pattern may improve long-term outcome after autologous osteochondral transplantation. But surface curvature and donor-site morbidity have to be considered as well when choosing the most suitable donor site.

Visual estimation of radioulnar incongruence in dogs using three-dimensional image rendering: an in vitro study based on computed tomographic imaging.

OBJECTIVE: To determine the sensitivity and specificity of visual estimation of radioulnar incongruence (RUI) in the canine elbow by use of 3-dimensional (3D) image rendering. STUDY DESIGN: Experimentally induced negative and positive RUI. SAMPLE POPULATION: Canine (>20 kg) cadaveric right thoracic limbs (n=8). METHODS: Radial shortening and lengthening of 1 and 2 mm were performed extending an established surgical in vitro model of RUI. Based on transverse computed tomographic (CT) scans of each radioulnar conformation, the subchondral radioulnar joint surface was reconstructed and visualized. A total of 64 3D models of RUI were blindly evaluated in a random manner by 3 independent observers. RUI was estimated subjectively at 1 mm precisely (-2, -1, 0, +1, +2) by visual inspection of the 3D models. RESULTS: Median sensitivity for identifying an incongruent joint was 0.86. Median specificity for identification of a congruent joint was 0.77. Analyzing the data only in respect to a congruent joint versus one with a shortened radius (positive RUI) resulted in a median sensitivity of 0.82, and a median specificity of 1.00. Interobserver agreement was 0.87. Repeatability was 0.96. CONCLUSION: Estimation of positive and negative RUI based on 3D surface models of the radioulnar articulation mimics gross inspection in a noninvasive manner, the latter being the ultimate gold standard for definitive diagnosis of any radioulnar step. The proposed technique is precise, reliable, and repeatable in vitro. CLINICAL RELEVANCE: Preoperative estimation of the type and degree of RUI is the basis for deciding which type of corrective or modifying osteotomy might be best suited to restore normal joint loads in vivo.

Continuous lumbar hemilaminectomy for intervertebral disc disease in an Amur tiger (Panthera tigris altaica).

A 13-yr-old Amur tiger (Panthera tigris altaica) was presented for an acute onset of paraplegia. Spinal imaging that included plain radiographs, myelography, and computed tomography performed under general anesthesia revealed lateralized spinal cord compression at the intervertebral disc space L4-5 caused by intervertebral disc extrusion. This extrusion was accompanied by an extensive epidural hemorrhage from L3 to L6. Therefore, a continuous hemilaminectomy from L3 to L6 was performed, resulting in complete decompression of the spinal cord. The tiger was ambulatory again 10 days after the surgery. This case suggests that the potential benefit of complete spinal cord decompression may outweigh the risk of causing clinically significant spinal instability after extensive decompression.

Partial lateral corpectomy for ventral extradural thoracic spinal cord compression in a cat.

A 7-year-old, female spayed, domestic shorthair cat was presented for ambulatory paraparesis. No trauma history was reported. Myelography and subsequent computed tomography revealed multiple ventrally located extradural spinal cord compressive lesions possibly due to intervertebral disc disease. Compression at the level of Th3-Th4 intervertebral disc space was considered responsible for the paraparesis. The lesion was approached via a right-sided lateral partial corpectomy as described for dogs. Complete spinal decompression was achieved, as documented intraoperatively by visual inspection and palpation of the spinal canal. No surgery related complications were encountered and the cat improved gradually within 8 weeks after the procedure. At 1 year follow-up only a slight proprioceptive deficit in the right hind limb could be noted. This is the first report of partial lateral corpectomy in a cat and should encourage the use of this technique even in small patients.

In vitro comparison of tibial plateau leveling osteotomy with and without use of a tibial plateau leveling jig.

OBJECTIVE: To evaluate the influence of a tibial plateau leveling jig on osteotomy orientation, fragment reduction, and postoperative tibial plateau angle (TPA) during tibial plateau leveling osteotomy (TPLO). STUDY DESIGN: In vitro experimental study. ANIMALS: Large-breed canine cadavers (n=20). METHODS: TPLO was performed on 40 hindlimbs using 4 methods. Group 1: Jig; dogs in dorsal recumbency with the osteotomy parallel to the distal jig pin. Groups 2-4: No jig; dogs in lateral recumbency with the osteotomy in a vertical orientation (group 2: tibia parallel to the table top; group 3: controlled superimposition of the femoral condyles; group 4: internal rotation of the tibia). Postoperative TPA, fragment reduction, and osteotomy orientation relative to the tibial plateau were compared. Positive or negative values denoted deviation from parallel relative to the tibial plateau. RESULTS: Postoperative TPA, fragment reduction, and proximodistal osteotomy orientation were not significantly different between groups. Craniocaudal osteotomy orientation was significantly different (P<.005) from the tibial plateau. Median deviations were -4.0 degrees (group 1), 11.8 degrees (group 2), 11.2 degrees (group 3), and 0.2 degrees (group 4). Group 1 was not significantly different from group 4. CONCLUSIONS: A jig is not essential for osteotomy orientation, tibial plateau rotation, or fragment reduction. Comparable results were achieved performing a vertical osteotomy with the tibia slightly internally rotated (10 degrees -15 degrees) and parallel to the table surface. CLINICAL RELEVANCE: TPLO without use of a jig reduces surgical trauma, is less time consuming, and reduces cost.

Magnetic resonance imaging and pathologic findings associated with necrotizing encephalitis in two Yorkshire terriers.

Two young adult Yorkshire terriers had neurologic signs consistent with forebrain and brainstem involvement or forebrain involvement alone. On magnetic resonance imaging studies there were asymmetric bilateral lesions mainly in the cerebral cortex, and in the diencephalon. These areas were hyperintense on T2-weighted and FLAIR images, but hypointense or isointense on T1-weighted images. Lesions had a varying degree of contrast enhancement. Areas which were isointense on T1-weighted images had no contrast enhancement or only foci of contrast enhancement. Lesions with hypointensity in T1-weighted images had no enhancement or more frequently ring-like enhancement around the lesion. Necrotizing encephalitis was confirmed pathohistologically in both dogs. The degree of contrast enhancement appeared to be related to the degree of lymphohistiocytic inflammation on histologic examination.

Síndrome da cauda flácida em cão da raca labrador retriever: primeiro relato no Brasil / Limber syndrome in a labrador retriever dog: first report in Brazil

A síndrome da cauda flácida é uma enfermidade que acomete cães de caca, principalmente Labradores Retriever e do grupo Pointer. Embora sua etiologia não esteja totalmente definida, sabe-se que sua ocorrência é precedida de esforco físico extenuante, exposicão ao frio ou água fria e confinamento em caixas de transporte. O presente trabalho descreve o caso de um cão da raca Labrador Retriever, macho não castrado, de quatro anos de idade que apresentou súbita dor e flacidez da cauda após banho frio. Fratura vertebral, síndrome da cauda eqüina, outras enfermidades da medula espinhal ou de glândulas adanais e afeccões prostáticas foram descartadas após exames auxiliares. A divulgacão deste relato é relevante uma vez que esta síndrome ainda não foi descrita no Brasil.

Use of arthroscopy in the treatment of fragmented medial coronoid process of the ulna: case report in a dog

O termo displasia de cotovelo (DC) descreve um estado anormal da articulação úmero-rádio-ulnar, causada por desenvolvimento inadequado da mesma. As lesões mais comumente encontradas são fragmentação do processo coronóide medial (FPCM) da ulna, osteocondrite dissecante (OCD) da porção medial do côndilo umeral, não união do processo ancôneo (NUPA) e incongruência articular (IA). O tratamento para FPCM pode ser conservativo ou cirúrgico. As técnicas cirúrgicas empregadas são variadas, mas em geral se baseiam na remoção de flaps cartilaginosos ou ósseos da articulação. Este trabalho relata o êxito do tratamento da FPCM da ulna utilizando-se a técnica de artroscopia.

Hemilaminectomia no tratamento de osteocondromatose vertebral em gato / Hemilaminectomy in the treatment of vertebral osteochondromatosis in a cat

O termo osteocondromatose refere-se a anormalidades proliferativas benignas de tecido cartilaginoso que acomete ossos de origem endocondral. Esta condição pode ser solitária ou múltipla e, neste último caso, é referida como exostose múltipla cartilaginosa (EMC). Em felinos, é caracterizada pelo surgimento em animais adultos e por apresentar desenvolvimento progressivo. A osteocondromatose pode ser silenciosa e o paciente poderá apresentar sinais clínicos quando o desenvolvimento das exostoses resultar em compressão de estruturas vitais, como a medula espinhal. Em felinos, a enfermidade não possui tratamento conhecido devido ao seu caráter recidivante. Este trabalho relata o êxito da aplicação de hemilaminectomia no tratamento de osteocondromatose vertebral em gato.