Peter Böttcher

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.

Partial Lateral Corpectomy of the Thoracolumbar Spine in 51 Dogs: Assessment of Slot Morphometry and Spinal Cord Decompression

Objective: To report slot morphometry, degree of spinal decompression, and factors influencing decompression after partial lateral corpectomy (PLC) of the thoracolumbar spine in dogs with intervertebral disc disease. Study Design: Case series. Animals: Dogs (n=51) with predominantly ventrally located spinal cord compression. Methods: PLC (n=60) were performed. Spinal cord compression was determined by computed tomographic (CT) myelography (n=46), myelography (n=2) or magnetic resonance imaging (n=3). Postsurgical CT images were used to evaluate slot dimensions and orientation, and spinal cord decompression. The influence of age, body weight, breed, breed type (chondrodystrophic, nonchondrodystrophic), disc location, lateralization and mineralization, presurgical compression, slot morphometry, and surgeon on degree of decompression were evaluated. Results: Mean slot depth was 64.1% of vertebral body width; mean height, 43.0% of vertebral body height; mean cranial extension, 29.5%; median caudal extension, 22.0% vertebral body length; mean angulation from horizontal, 6.3°. Decompression was satisfactory in 90% of sites after PLC (58% complete, 32% good). None of the analyzed factors significantly influenced decompression. All lumbar spine PLC resulted in complete or good decompression compared with 83% after thoracic PLC (P=.052). Deeper slots tended to allow more complete decompression (P=.058). Conclusions: Thoracolumbar PLC results in satisfactory decompression in most cases with a better outcome in the lumbar spine than the thoracic spine. Achieving a slot depth equal to 2/3 of vertebral body width might facilitate complete decompression.OBJECTIVE To report slot morphometry, degree of spinal decompression, and factors influencing decompression after partial lateral corpectomy (PLC) of the thoracolumbar spine in dogs with intervertebral disc disease. STUDY DESIGN Case series. ANIMALS Dogs (n=51) with predominantly ventrally located spinal cord compression. METHODS PLC (n=60) were performed. Spinal cord compression was determined by computed tomographic (CT) myelography (n=46), myelography (n=2) or magnetic resonance imaging (n=3). Postsurgical CT images were used to evaluate slot dimensions and orientation, and spinal cord decompression. The influence of age, body weight, breed, breed type (chondrodystrophic, nonchondrodystrophic), disc location, lateralization and mineralization, presurgical compression, slot morphometry, and surgeon on degree of decompression were evaluated. RESULTS Mean slot depth was 64.1% of vertebral body width; mean height, 43.0% of vertebral body height; mean cranial extension, 29.5%; median caudal extension, 22.0% vertebral body length; mean angulation from horizontal, 6.3°. Decompression was satisfactory in 90% of sites after PLC (58% complete, 32% good). None of the analyzed factors significantly influenced decompression. All lumbar spine PLC resulted in complete or good decompression compared with 83% after thoracic PLC (P=.052). Deeper slots tended to allow more complete decompression (P=.058). CONCLUSIONS Thoracolumbar PLC results in satisfactory decompression in most cases with a better outcome in the lumbar spine than the thoracic spine. Achieving a slot depth equal to 2/3 of vertebral body width might facilitate complete decompression.

A novel pin distraction device for arthroscopic assessment of the medial meniscus in dogs.

OBJECTIVE To describe an extra-articular joint distractor for meniscal examination and treatment during canine stifle arthroscopy. STUDY DESIGN Case series. ANIMALS Dogs >or=20 kg with suspected cranial cruciate ligament (CrCL) deficiency. METHODS A custom designed linear side bar was constructed to allow invasive pin distraction of the stifle joint. Its design efficacy for distraction of the medial joint compartment, observation and probing of the medial meniscus, and value during meniscal surgery was evaluated by clinical use. RESULTS Application of the stifle distractor medial to the stifle joint using 2 negative threaded pins was easily performed percutaneously without the need of power equipment; however, unintended intra-articular placement of 1 threaded pin occurred in 2 stifles, without appreciable consequence to joint function. Observation as well as thorough probing of the caudal horn of the medial meniscus, even in the presence of a prominent remnant of the CrCL or severe periarticular fibrosis, was possible. Partial meniscectomy was effectively performed as needed without apparent damage to the associated articular surfaces. CONCLUSIONS Distraction and translation of the medial compartment of the stifle joint using invasive pin distraction allowed observation and palpation of the caudal horn of the medial meniscus so that assessment and treatment were readily accomplished without apparent morbidity. CLINICAL RELEVANCE With careful attention to accurate pin placement, invasive pin distraction of the medial compartment of the canine stifle joint may improve arthroscopic evaluation and treatment of meniscal pathology.

Topographic and age-dependent distribution of subchondral bone density in the elbow joints of clinically normal dogs.

OBJECTIVE To investigate topographic and age-dependent adaptation of subchondral bone density in the elbow joints of healthy dogs by means of computed tomographic osteoabsorptiometry (CTOAM). Animals-42 elbow joints of 29 clinically normal dogs of various breeds and ages. PROCEDURES Subchondral bone densities of the humeral, radial, and ulnar joint surfaces of the elbow relative to a water-hydroxyapatite phantom were assessed by means of CTOAM. Distribution patterns in juvenile, adult, and geriatric dogs (age, < 1 year, 1 to 8 years, and > 8 years, respectively) were determined and compared within and among groups. RESULTS An area of increased subchondral bone density was detected in the humerus distomedially and cranially on the trochlea and in the olecranon fossa. The ulna had maximum bone densities on the anconeal and medial coronoid processes. Increased bone density was detected in the craniomedial region of the joint surface of the radius. A significant age-dependent increase in subchondral bone density was revealed in elbow joint surfaces of the radius, ulna, and humerus. Mean subchondral bone density of the radius was significantly less than that of the ulna in paired comparisons for all dogs combined and in adult and geriatric, but not juvenile, dog groups. CONCLUSIONS AND CLINICAL RELEVANCE An age-dependent increase in subchondral bone density at the elbow joint was revealed. Maximal relative subchondral bone densities were detected consistently at the medial coronoid process and central aspect of the humeral trochlea, regions that are commonly affected in dogs with elbow dysplasia.

Computer-assisted magnetic resonance imaging brain morphometry in American Staffordshire Terriers with cerebellar cortical degeneration.

BACKGROUND Cerebellar cortical degeneration exists in American Staffordshire Terriers. Magnetic resonance imaging (MRI) can be suggestive, but a definitive diagnosis requires histopathology. HYPOTHESIS Computer-assisted MRI morphometry can be used to distinguish between American Staffordshire Terriers with or without cerebellar cortical degeneration. ANIMALS Normal American Staffordshire Terriers (n = 17) and those with clinical signs of cerebellar cortical degeneration (n = 14). METHODS This was a partly retrospective and partly prospective study. Causes of cerebellar disease were ruled out with brain MRI, cerebrospinal fluid (CSF) analysis, CBC, blood biochemistry, and clinical follow-up. On T2-weighted midsagittal MR images, the following parameters were calculated: size of the cerebellum relative to the entire brain, size of the CSF space surrounding the cerebellum relative to the cerebellum, and 2 threshold-dependent cerebellar CSF indices (with and without surrounding CSF). RESULTS Statistical analyses indicated a significantly lower relative cerebellar size (P < .001) and a larger relative cerebellar CSF space (P < .001) in dogs with cerebellar cortical degeneration. The measurement of relative cerebellar size could distinguish between affected and nonaffected dogs with a sensitivity and a specificity of 93 and 94%, respectively, using a cut-off of 13.3%. Using a cut-off of 12.8%, the measurement of relative CSF space could distinguish between both groups with a sensitivity of 93% and a specificity of 100%. There was a significant difference in 1 of the 2 CSF indices between affected and normal dogs. CONCLUSIONS AND CLINICAL IMPORTANCE Relative cerebellar size and relative CSF space calculated from MRI are effective in American Staffordshire Terriers to differentiate between normal animals and those with cerebellar cortical degeneration.

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.

Estimation of joint incongruence in dysplastic canine elbows before and after dynamic proximal ulnar osteotomy.

OBJECTIVE To characterize joint incongruence in dysplastic canine elbows before and after dynamic proximal ulnar osteotomy (DPUO). STUDY DESIGN Clinical, prospective study. ANIMALS Dogs (n = 10; 12 elbows) with ≥ 2 mm radioulnar incongruence (RUI), FCP, and/or OCD. METHODS Computed tomography in a nonload bearing position was used to generate in silico 3D models of the elbow joint before DPUO, and this was repeated after DPUO union (median 3 months postoperatively). On these models, RUI, humeroradial and humeroulnar subchondral joint space width (SJSW) as well as alignment of the proximal ulnar segment were investigated. RESULTS RUI at the medial coronoid process (MCP) decreased (P = .001), while it increased at the lateral coronoid process (P = .0005), and remained unchanged at the level of the trochlear ridge (P = .25). SJSW at the MCP increased (P = .001), changing from focal joint space collapse preoperatively to a more homogeneous pattern of moderate SJSW at follow-up. The proximal ulnar segment rotated in all 3 planes with caudal tipping at the level of the osteotomy and varus deformity, while no axial translation could be noted. CONCLUSIONS DPUO results in reduction of RUI and amelioration of focal contact area at the MCP. This effect is the result of a complex three-dimensional rotation of the proximal ulnar segment, rather than axial shift.

Neurologic outcome after thoracolumbar partial lateral corpectomy for intervertebral disc disease in 72 dogs.

OBJECTIVE To determine neurologic outcome and factors influencing outcome after thoracolumbar partial lateral corpectomy (PLC) in dogs with intervertebral disc disease (IVDD) causing ventral spinal cord compression. STUDY DESIGN Retrospective case series. ANIMALS Dogs with IVDD (n = 72; 87 PLC). METHODS Dogs with IVDD between T9 and L5 were included if treated by at least 1 PLC. Exclusion criteria were: previous spinal surgery, combination of PLC with another surgical procedure. Neurologic outcome was assessed by: (1) modified Frankel score (MFS) based on neurologic examinations at 4 time points (before surgery, immediately after PLC, at discharge and 4 weeks after PLC); and (2) owner questionnaire. The association of the following factors with neurologic outcome was analyzed: age, body weight, duration of current neurologic dysfunction (acute, chronic), IVDD localization, breed (chondrodystrophic, nonchondrodystrophic), number of PLCs, degree of presurgical spinal cord compression and postsurgical decompression, slot depth, presurgical MFS. Presurgical spinal cord compression was determined by CT myelography (71 dogs) or MRI (1 dog), whereas postsurgical decompression and slot depth were determined on CT myelography (69 dogs). RESULTS MFS was improved in 18.7%, 31.7%, and 64.2% of dogs at the 3 postsurgical assessments, whereas it was unchanged in 62.6%, 52.8%, and 32.0% at corresponding time points. Based on owner questionnaire, 91.4% of dogs were ambulatory 6 months postsurgically with 74.5% having a normal gait. Most improvement in neurologic function developed within 6 months after surgery. Presurgical MFS was the only variable significantly associated with several neurologic outcome measurements (P < .01). CONCLUSIONS PLC is an option for decompression in ventrally compressing thoracolumbar IVDD. Prognosis is associated with presurgical neurologic condition.Objective To determine neurologic outcome and factors influencing outcome after thoracolumbar partial lateral corpectomy (PLC) in dogs with intervertebral disc disease (IVDD) causing ventral spinal cord compression. Study Design Retrospective case series. Animals Dogs with IVDD (n = 72; 87 PLC). Methods Dogs with IVDD between T9 and L5 were included if treated by at least 1 PLC. Exclusion criteria were: previous spinal surgery, combination of PLC with another surgical procedure. Neurologic outcome was assessed by: (1) modified Frankel score (MFS) based on neurologic examinations at 4 time points (before surgery, immediately after PLC, at discharge and 4 weeks after PLC); and (2) owner questionnaire. The association of the following factors with neurologic outcome was analyzed: age, body weight, duration of current neurologic dysfunction (acute, chronic), IVDD localization, breed (chondrodystrophic, nonchondrodystrophic), number of PLCs, degree of presurgical spinal cord compression and postsurgical decompression, slot depth, presurgical MFS. Presurgical spinal cord compression was determined by CT myelography (71 dogs) or MRI (1 dog), whereas postsurgical decompression and slot depth were determined on CT myelography (69 dogs). Results MFS was improved in 18.7%, 31.7%, and 64.2% of dogs at the 3 postsurgical assessments, whereas it was unchanged in 62.6%, 52.8%, and 32.0% at corresponding time points. Based on owner questionnaire, 91.4% of dogs were ambulatory 6 months postsurgically with 74.5% having a normal gait. Most improvement in neurologic function developed within 6 months after surgery. Presurgical MFS was the only variable significantly associated with several neurologic outcome measurements (P < .01). Conclusions PLC is an option for decompression in ventrally compressing thoracolumbar IVDD. Prognosis is associated with presurgical neurologic condition.

Sensitivity and specificity of 3D models of the radioulnar joint cup in combination with a sphere fitted to the ulnar trochlear notch for estimation of radioulnar incongruence in vitro.

OBJECTIVE To determine the sensitivity and specificity of estimation of radioulnar incongruence (RUI) by use of 3-dimensional (3D) image renderings in combination with a sphere fitted to the ulnar trochlear notch. STUDY DESIGN In vitro study. SAMPLE POPULATION Right forelimbs (n = 8) of canine cadavers weighing >20 kg. METHODS CT-based 3D models (n = 63) of the radioulnar joint cup with different states of RUI were used. A sphere was fitted to the trochlear notch of each of the models and 2 independent observers estimated RUI based on the relation of the sphere and the radial joint surface blinded to the true state of RUI at 1 mm precisely (-2 mm to +2 mm). RESULTS Mean sensitivity and specificity for detecting any form of incongruent joint was 0.94 and 0.89, respectively. Evaluating a positive step (short radius) versus a congruent joint resulted in a mean sensitivity and specificity of 0.89 and 0.96, respectively. A negative RUI (short ulna) was diagnosed with a mean sensitivity and specificity of 1.00 and 0.92, respectively. Intra-class-correlation coefficient for inter-observer agreement was 0.99. CONCLUSIONS Fitting a sphere to the ulnar trochlea notch significantly improves diagnostic accuracy of 3D models of the radioulnar joint cup when diagnosing RUI.Objective To determine the sensitivity and specificity of estimation of radioulnar incongruence (RUI) by use of 3-dimensional (3D) image renderings in combination with a sphere fitted to the ulnar trochlear notch. Study Design In vitro study. Sample Population Right forelimbs (n = 8) of canine cadavers weighing >20 kg. Methods CT-based 3D models (n = 63) of the radioulnar joint cup with different states of RUI were used. A sphere was fitted to the trochlear notch of each of the models and 2 independent observers estimated RUI based on the relation of the sphere and the radial joint surface blinded to the true state of RUI at 1 mm precisely (−2 mm to +2 mm). Results Mean sensitivity and specificity for detecting any form of incongruent joint was 0.94 and 0.89, respectively. Evaluating a positive step (short radius) versus a congruent joint resulted in a mean sensitivity and specificity of 0.89 and 0.96, respectively. A negative RUI (short ulna) was diagnosed with a mean sensitivity and specificity of 1.00 and 0.92, respectively. Intra-class-correlation coefficient for inter-observer agreement was 0.99. Conclusions Fitting a sphere to the ulnar trochlea notch significantly improves diagnostic accuracy of 3D models of the radioulnar joint cup when diagnosing RUI.