Vera Grevel

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.

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.

Sensitivity and specificity of arthroscopic estimation of positive and negative radio-ulnar incongruence in dogs. An in vitro study.

OBJECTIVES To determine the sensitivity and specificity of arthroscopic estimation of positive and negative radio-ulnar incongruence (RUI) in the canine elbow joint. METHODS Experimental radial shortening and lengthening by 1 and 2 mm increments were performed in nine right elbow joints, extending an established surgical in vitro model of RUI. Arthroscopic estimation of each artificially produced radio-ulnar joint conformation (RUJC) was done using a graduated hook probe. A total of 72 RUJC were blindly evaluated in a random manner by an independent investigator and estimated in 1 mm increments (-2, -1, 0, +1, +2). RESULTS The sensitivity for identification of an incongruent joint was 0.98 (95% CI: 0.90 to 0.99). The specificity for identification of a congruent joint was 0.89 (95% CI: 0.65 to 0.98). Analysing the data only in respect to a congruent joint versus one with a shortened radius (positive RUI) resulted in a sensitivity of 0.96 (95% CI: 0.80 to 0.99) and a specificity of 1.00 (95% CI: 0.92 to 1.00). CLINICAL SIGNIFICANCE Accurate estimation of RUI in dogs affected by elbow dysplasia might improve functional outcome and prevent osteoarthritis when corrective or modifying osteotomies are being considered as part of the treatment plan. Arthroscopy has been shown to be highly accurate and precise in detecting both positive and negative RUI in vitro. However, its diagnostic strength under clinical conditions still has to be proven.

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 Pearsons 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.

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.

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.

Cartilage thickness and split-line pattern at the canine humeral trochlea

OBJECTIVE To characterise the humeral trochlea in middle to large breed dogs in respect to split-line pattern and cartilage thickness. METHODS In 15 paired cadaveric elbow joints of mature dogs (>20 kg body weight) collagen network orientation of the hyaline cartilage of the humeral trochlea was visualised using a traditional split-line technique in which a dissecting needle dipped in India ink was inserted into the cartilage (n = 10). Cartilage thickness was measured radiographically on osteochondral plugs harvested at four representative locations within the joint surface of the humeral trochlea (n = 15). RESULTS The joint surface of the humeral trochlea showed a distinct pattern of centripetally oriented split-lines with less pronounced or even absent split-lines caudo- proximally towards the olecranon fossa. Median cartilage thickness at the canine humeral trochlea was 0.51 mm (interquartile range: 0.42 - 0.61 mm). Centrally, at the region where osteochondrosis lesions commonly occur in middle to large breed dogs, the median cartilage thickness was 0.55 mm (interquartile range: 0.48 - 0.62 mm). CLINICAL SIGNIFICANCE When focusing on anatomical joint resurfacing while performing osteochondral transplantation at the canine humeral trochlea, transplants should be implanted such that their split-lines are oriented centripetally. Hyaline cartilage thickness of transferred grafts should be in the range of half a millimetre to optimally match the situation at the canine humeral trochlea.

Continuous Lumbar Hemilaminectomy for Intervertebral Disc Disease in an Amur Tiger (Panthera tigris altaica)

Abstract 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.

High‐dose‐rate brachytherapy for intranasal tumours in dogs: results of a pilot study

This prospective study describes the feasibility and toxicity of (192)Iridium high-dose-rate (HDR) brachytherapy as an alternative strategy for the treatment of canine intranasal tumours. Fifteen dogs with malignant intranasal tumours were treated twice weekly using a hypofractionated protocol with eight fractions, 5 Gy per fraction, resulting in a total dose of 40 Gy. Acute and chronic adverse side-effects appeared to be rare. Only 7% of the acute side-effects and 5% of the chronic were classified as severe (grade 3). Eight dogs showed clinical complete remission, and five dogs had partial remission, with a resolution of tumour-related symptoms. Magnetic resonance imaging showed a reduced tumour mass in 12 cases. Median survival time was 17 months (range 4-48 months), with four dogs (three without disease) still alive. Median time to recurrence of these dogs was 14 months. In nine dogs, progression or recurrence of the tumour was the cause of death. This study suggests that HDR brachytherapy is feasible and well tolerated.