Accuracy of Computerized Tomographic Evaluation of Canine Radio-Ulnar Incongruence In Vitro

[Arthroscopic removal of the fragmented medial coronoid process in dogs - Evaluation of treatment results with special reference to postoperative computed tomography and residual particles]

OBJECTIVE

The aim of this study was to assess the treatment success of dogs with medial coronoid disease (here: Fragmented Coronoid Process [FCP]) following arthroscopically performed subtotal coronoidectomy by the use of subjective and objective gait analysis and the evaluation of osteoarthritis progression in addition to their correlation with the findings from postoperative computed tomography. In particular, the clinical relevance of residual particles remaining postoperatively was to be evaluated.

MATERIAL AND METHODS

Thirty elbows from 24 dogs of different breeds were examined clinically, orthopedically, using gait analysis as well as radiographically at least 6 months after unilateral or bilateral subtotal coronoidectomy. The results were compared with the preoperative findings of the corresponding examinations and postoperative computed tomography.

RESULTS

79.2% (19/24) of the patients improved by at least one degree of lameness in the orthopedic examination, 66.7% (16/24) were free of lameness. 60% (18/30 joints) showed an increase in the degree of arthrosis. Postoperative computed tomography revealed small residual bone particles (<1 mm) in the joint space or soft tissue in 56.7% (17/30) of the joints. No significant association was evident between residual lameness and residual particles remaining within the joint postoperatively. An association between persistent lameness and progression of arthrosis was also not be demonstrable.

CONCLUSION

No evidence was apparent supporting a link between residues of small bone particles after arthroscopic subtotal coronoidectomy and postoperative lameness. The progression of osteoarthritis could not be interrupted despite the surgical intervention.

CLINICAL RELEVANCE

When small residual particles (<1 mm) remain after subtotal coronoidectomy, these do not appear to have any influence on the clinical outcome.

Microcomputed tomographic analysis of the ulnar trochlear notch in medium- and large-breed canine cadavers with and without medial coronoid disease

Medial coronoid disease (MCD) is a common disease often associated with thoracic limb lameness in medium- and large-breed dogs. The term MCD includes subchondral changes of the medial coronoid process (MCP), as well as pathologies of both cartilaginous surfaces. As there are only a few comprehensive and detailed studies on the trabecular structure of the medial coronoid, the goal of this study was to compare the trabecular structure of the ulnar trochlear notch of canine cadavers with and without MCD using different micro-computed tomographic (micro-CT) parameters. Fifty-eight elbow joints from 29 canine cadavers of MCD-predisposed and non-predisposed breeds (control group) were examined radiographically, macroscopically and by microcomputed tomography. The study included elbow joints of eight Labrador Retrievers (21.6-37 kg), seven Golden Retrievers (26.3-42 kg), seven Bernese Mountain dogs (31-47 kg) and seven dogs of non-predisposed breeds (19.7-52 kg) (control group). The final diagnosis of MCD was based on necropsy and micro-computed tomographic examinations. Micro-CT examinations were performed using XtremeCT II (Scanco Medical, Zurich, Switzerland) and the following parameters were examined: bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular number (Tb.N), connectivity density (Conn.D) and degree of anisotropy (DA). Twenty-four elbows of 44 elbows of the predisposed breeds (Labrador Retrievers, Golden Retrievers Bernese Mountain dogs) showed subchondral changes and lesions of the cartilage surfaces. The result of this study is a higher density (BV/TV) of the trabecular bone of the ulnar trochlear notch in elbows affected by MCD compared to the control group. The increased density due to trabecular reconstruction in the ulnar trochlear notch is likely the result of selectively increased loading during life.

Comparative evaluation of radiographic and computed tomographic findings in dogs with bilateral medial coronoid disease (MCD) presenting with unilateral forelimb lameness

OBJECTIVES

The purpose of this study was to compare the radiographic and computed tomographic (CT) findings of dogs with diagnosed bilateral medial coronoid disease, which showed clinically only unilateral lameness of the forelimbs.

MATERIALS AND METHODS

Medical records, including radiographs and CT images of dogs with diagnosed bilateral MCD showing only a unilateral forelimb lameness clinically were reviewed retrospectively. Depending on the gait of each dog we established two groups to investigate their radiographs and CT data comparatively. Group I: affected non-lame limb. Group II: affected lame limb. Several evaluation systems were used to assess which factors are important for clinical decision making and a patient tailored therapeutic plan.

RESULTS

Data from 84 affected elbow joints (42 dogs) diagnosed with MCD by computed tomography were included. Both the radiological and the CT analysis showed that there are significant differences between Groups I and II. Group I had a lower modified International Elbow Working Group Score (IEWG), the values of the Trochlear notch sclerosis were only slightly deviated, and this group showed less often a dislocation of the fragment compared to group II. Furthermore, the size of the fragment (both the median and the mean value) of the forelimbs from group II was almost twice as big as the one from group I. The following sizes of the fragments were calculated (group I versus (vs.) group II)-median: 0.09 cm2 vs. 0.16 cm2, mean value: 0.112 cm2 vs. 0.202 cm2. It could be shown that a larger fragment is more likely to dislocate than a smaller one.

CLINICAL SIGNIFICANCE

This study provides some evidence towards a better understanding of which diagnostic parameters and findings might be important in clinical decision making. Nevertheless, a "decision tree" for the correct therapy of MCD could not be determined in this study.

Computed tomographic evaluation of elbow congruity during arthroscopy in a canine cadaveric model

Objective: To assess the effect of arthro-scope insertion, using a carbon-fibre rod model, on humero-radial, humero-ulnar and radio-ulnar congruity, as assessed by computed tomography (CT).

Methods: Cadaveric Greyhound elbow joints were assessed at a flexion angle of 135 ± 5° using CT. For condition 1, a 36 mm fulcrum induced cubital valgus, as used to aid arthro-scope insertion. For conditions 2 and 3, a single 1.8 or 2.5 mm diameter rod was inserted under arthroscopic guidance to simulate arthroscope position for assessment of the medial coronoid process. Repeat CT scans were obtained for all conditions and parasagittal sections were reconstructed to evaluate medial, axial and lateral positions within the elbow. Humero-radial, humeroulnar, and radio-ulnar congruity measurements were obtained. Differences between groups were assessed using repeated measures analysis of variance.

Results: Mean (±SD) change in radio-ulnar step between conditions 1 and 3 was 0.6 ± 0.3 mm (axial), 0.8 ± 0.6 mm (medial), and 0.5 ± 0.1 mm (lateral). Insertion of rods induced a significant decrease in radio-ulnar step in all planes. Significant differences were also identified between groups for humero-radial, humero-ulnar, and radio-ulnar congruity.

Clinical significance: Insertion of carbon-fibre rods as a model for elbow arthroscope insertion induces elbow incongruity. Changes in radio-ulnar congruity are small but the effect of arthroscope diameter should be considered when assessing elbow congruity.

Computerized measurements of radiographic anatomical parameters of the elbow joint in Bernese Mountain Dogs

Objective: Comparison of two methods for evaluation of anatomical parameters of elbow joints in Bernese Mountain Dogs.

Study design: Radiographic analysis.

Animals: Nine hundred and thirty-one radiographs of elbow joints from 305 Bernese Mountain Dogs.

Material and methods: The angles OL, PA, RA and UL were measured according to the Mues method and the Radius of the humeral condyle, Opening angle beta, Quotient Q and Ae, Area X, Step 1 and Step 2 according to the Viehmann method. The radiographs were divided according to their angle of flexion into five groups: 0–30°, 31–60°, 61–90°, 91–120° and >120°. The difference and the correlation between measured values and the elbow dysplasia (ED) score was calculated and compared.

Results: The average values of angle OL, PA and RA, Area X, Step 1 and Step 2 were significantly different within the different elbow flexion angle groups. The values of Opening angle beta, Quotients Q and Ae as well as Radius of the humeral condyle varied independently from the degree of the elbow flexion on the radiograph. The angles OL, PA and RA and the Radius of the humeral condyle, the Opening angle beta, the Quotients Q and Ae, Step 1 and Step 2 correlated with the ED score.

Conclusion: In contrast to the method of Mues, the majority of the measured parameters of the method of Viehmann were not influenced by the degree of flexion of the elbow joint and correlated with the ED score. Clinical relevance: The method of Viehmann warrants consideration for the evaluation of radiographs of elbow joints in the Bernese Mountain Dog for ED.

This article is based on a study first reported in S. Stein's doctoral thesis, which was presented on 08.05.2007 and published thereafter in full by Mensch & Buch Verlag. This abridged and translated version is now being published with the kind permission of Mensch & Buch Verlag.

Avaliação morfológica e morfométrica da articulação umerorradioulnar em cães através de exames radiográficos e por tomografia computadorizada

RESUMO: Este estudo teve como objetivo apresentar de forma detalhada dados morfológicos e morfométricos da articulação umerorradioulnar de cães de raça definida avaliados por meio de exames físicos, radiográficos e tomográficos. A amostra dessa pesquisa constituiu-se de 44 cotovelos de cães com idades variadas. Para análise de informações obtidas, o coeficiente kappa e de correlação interclasse e associação foram realizados. Constatou-se que o desempenho individual de cada projeção radiográfica teve pobre concordância com o exame tomográfico; não houve concordância entre os observadores para as mensurações do ângulo da incisura ulnar ao exame radiográfico e tomográfico. Porém houve boa/moderada concordância para mensuração da incongruência radioulnar no plano sagital entre os observadores. Concluiu-se que nenhuma das cinco incidências radiográficas foi superior para análise radiográfica, uma vez que cada projeção apresentou melhor identificação de um compartimento do cotovelo. Medidas ao exame tomográfico para incongruência radioulnar não apresentaram reprodutibilidade no plano de reconstrução frontal, entretanto no corte sagital apresentaram boa e moderada concordância entre os observadores e que a mensuração do ângulo da incisura ulnar não apresentou repetibilidade ao exame radiográfico e nem reprodutibilidade ao exame tomográfico. Esses resultados contribuem para melhor utilização de cada exame de acordo com a região a ser avaliada bem como ressaltam a necessidade da somatória de múltiplos exames de imagem para a correta avaliação desta afecção.

COMPUTED TOMOGRAPHIC FINDINGS IN CANINE ELBOWS ARTHROSCOPICALLY DIAGNOSED WITH EROSION OF THE MEDIAL COMPARTMENT: AN ANALYTICAL METHOD COMPARISON STUDY

Medial compartment erosion is an advanced stage of medial coronoid disease, an important cause of elbow lameness in dogs, with treatment and the expected prognosis depending on the extent of the cartilage lesions. The identification of specific computed tomographic (CT) findings might facilitate the nonsurgical diagnosis and add to treatment decision making. Aims of this retrospective, analytical, method comparison study were to describe CT findings in elbows of dogs arthroscopically diagnosed with medial compartment erosion and to compare CT vs. arthroscopic findings. A total of 56 elbows met inclusion criteria. Elbows with focal (n = 13), diffuse (n = 11), and complete (n = 32) erosion were compared. Prevalence findings for CT lesions were as follows: periarticular osteophytosis (100%), abnormal shape of the medial coronoid process of the ulna (96.4%), and subchondral bone defect of the medial part of the humeral condyle (MHC; 96.4%). The three groups significantly differed for presence of medial coronoid process fragmentation, radial head subchondral bone sclerosis, and widening of the humeroulnar joint space. No significant agreement was found between CT and arthroscopy for presence of a subchondral bone defect of the MHC. A significant agreement was found between CT and arthroscopy for presence of fragmentation of the medial coronoid process. However, some of the calcified body/fragment(s) visualized on CT in the region of the medial coronoid process could not be identified via arthroscopy. Findings indicated that an accurate estimation of the extent of the elbow cartilage lesions still requires arthroscopic joint inspection.

Bi-Oblique Dynamic Proximal Ulnar Osteotomy: Surgical Technique and Clinical Outcome in 86 Dogs

OBJECTIVE

To describe the technique of bi-oblique dynamic proximal ulnar osteotomy (BODPUO) and report the clinical outcome in a series of dog with medial compartment disease and other developmental elbow diseases.

STUDY DESIGN

Retrospective case series.

ANIMALS

Dogs (n=86; 120 elbows) treated for elbow disease with BODPUO.

METHODS

Medical records and diagnostic images were reviewed. Type and frequency of complications and treatment required were recorded. Force plate data were reported in dogs for which data had been recorded preoperatively and at follow-up.

RESULTS

Mean (standard deviation) final follow-up was 23.4 (35.6) weeks. There were minor complications in 15 elbows (12%, 14 dogs). There were no major complications. The caudo-cranial and latero-medial mean osteotomy angles were 55° (7°) and 48° (10°), respectively. The most caudo-proximal point of the osteotomy was located at a mean of 39% (5%) of the total ulnar length from the olecranon. Sixty of 68 elbows (88%) were considered healed by 4 months postoperative based on radiographs. Subjective lameness scores were significantly decreased by final follow-up for all dogs. For dogs treated with BODPUO alone for medial compartment disease, peak vertical force was significantly higher at 6 months postoperative.

CONCLUSION

Dogs with medial compartment disease undergoing BODPUO showed clinical improvement in the 6 month follow-up. No complications required surgical intervention.

Medical Infrared Imaging of Normal and Dysplastic Elbows in Dogs

OBJECTIVE

To investigate the ability of medical infrared imaging to differentiate between normal canine elbows and those with abnormal elbows (elbow dysplasia).

STUDY DESIGN

Prospective cohort study.

ANIMALS

Dogs with normal (n = 15) and abnormal (n = 14) elbows.

METHODS

Infrared imaging was performed on all dogs and data analyzed via descriptive statistics and image pattern analysis software. Animals with elbow dysplasia had arthroscopic procedures to confirm the presence of elbow disease.

RESULTS

Computer recognition pattern analysis was up to 100% correct in identifying abnormal elbows and normal elbows, with the medial images most consistent. The caudal, lateral, and cranial images correctly identified 83-100% abnormal elbows. The caudal and lateral images correctly identified 83% normal elbows. A significant difference in temperature was found between normal and abnormal elbows for the cranial full region of interest, lateral images, and each quadrant.

CONCLUSION

Medical infrared imaging was able to correctly identify known abnormal and known normal elbows in dogs.

Arthroscopic-guided ulnar distraction for the correction of elbow incongruency in four dogs

Four skeletally immature, small breed dogs (five elbows) with elbow incongruency were evaluated for forelimb lameness. Findings on clinical examination included pain, effusion and decreased range of motion of the affected elbow. Radiography, computed tomography and arthroscopy demonstrated elbow incongruency in all dogs. Fragmented medial coronoid process was diagnosed arthroscopically in three dogs (four elbows). Arthroscopic subtotal coronoidectomy was performed in all cases of fragmented medial coronoid process. Incongruency was corrected with acute ulnar lengthening under arthroscopic visualisation. The ulna was stabilised with a plate following correction. In two elbows an ostectomy of the anconeal process was performed to prevent impingement against the olecranon fossa. All dogs demonstrated improvement in lameness scores and client-scored visual analogue scale scores. Postoperative computed tomography showed significant improvement in elbow incongruency in all dogs. Arthroscopic-guided ulnar lengthening may be considered as a valid treatment in severe cases of elbow incongruency.

Arthroscopic treatment of fragmented coronoid process with severe elbow incongruity. Long-term follow-up in eight Bernese Mountain Dogs

The purpose of this study was to investigate the long-term treatment results of fragmented coronoid process (FCP) in joints with a radio-ulnar step greater than 3 mm. Treatment of these patients only consisted of fragment removal, without correction of the incongruity. The eight Bernese Mountain Dogs (11 joints) included in this study showed obvious clinical signs of elbow disease and were diagnosed with severe elbow incongruity and concomitant FCP in the time period from 1999-2003. At that time, elbow radiography, computed tomography, and arthroscopy were performed. The mean follow-up period was 5.6 years. The follow-up consisted of a telephone questionnaire combined with a clinical and radiographic re-evaluation at our clinic. The questionnaire revealed that all dogs were either free of lameness or only lame following heavy exercise. One dog sporadically required medication after heavy exercise. The owner satisfaction rate was 100%. The clinical re-evaluation did not reveal any signs of pain or lameness in all cases. Range-of- motion was decreased in nine of the 11 elbows. Radiographs revealed an increase in severity of osteoarthritis in every case.In this case series, arthroscopic fragment removal without treatment of incongruity was demonstrated to be a valuable treatment option and may provide a satisfactory long-term outcome.

Computed tomography of ununited anconeal process in the dog

OBJECTIVE

The purpose of this study was to describe computed tomography (CT) features of the ununited anconeal process and relate them with the following elbow dysplasia signs: medial coronoid disease, medial humeral condyle changes, osteoarthritis (OA), and radioulnar incongruence.

METHODS

Computed tomographic images of dogs older than six months with an ununited anconeal process were evaluated (n = 13). Ununited anconeal process features were described as being complete or incomplete, and the degree of displacement, volume, and presence of cysts and sclerosis were also evaluated. Medial coronoid disease was defined as an irregular medial coronoid process shape, presence of sclerosis and fragmentation. Medial humeral condyle changes were defined as subchondral bone flattening, lucencies, and sclerosis. Osteoarthritis was graded depending on the osteophytes size. Radioulnar incongruence was measured on a sagittal view at the base of the medial coronoid process.

RESULTS

Eleven elbows had a complete and two had an incomplete ununited anconeal process. All ununited anconeal processes had cystic and sclerotic lesions. Seven ununited anconeal processes were displaced and six were non-displaced. Mean ununited anconeal process volume was 1.35 cm3 (0.61 cm³ - 2.08 cm³). Twelve elbows had signs of medial coronoid disease (4 of them with a fragmented medial coronoid process), and one elbow did not show any evidence of medial coronoid disease. Ten elbows had medial humeral condyle changes. One elbow had grade 1 OA, seven elbows had grade 2, and five elbows grade 3. All elbows had radioulnar incongruence: three elbows had a negative and 10 elbows had a positive radioulnar incongruence. Mean radioulnar incongruence was 1.49 mm (0.63 mm - 2.61 mm). Computed tomographic findings were similar in the majority of the elbows studied: complete ununited anconeal processes with signs of medial coronoid disease, positive radioulnar incongruence, high grade of OA, sclerotic medial humeral condyle changes, and large ununited anconeal process volumes.

CLINICAL SIGNIFICANCE

Incomplete small ununited anconeal process volumes could be associated with a lower incidence of medial coronoid disease or medial humeral condyle changes. We recommend performing preoperative CT of elbows with an ununited anconeal process to evaluate concurrent lesions.

Quantification of humeroulnar incongruity in labrador retrievers with and without medial coronoid disease

OBJECTIVE

To quantify humeroulnar incongruity on elbow radiographs in Labrador Retrievers with or without medial coronoid disease (MCD).

STUDY DESIGN

Retrospective study of 92 elbows.

SAMPLE POPULATION

Radiographic projections of elbow joints from Labrador Retrievers with MCD (n = 42 elbows; 26 dogs) and without MCD (n = 50 elbows; 25 dogs).

PROCEDURE

The congruity of the humeroulnar joint was measured using an index of subluxation (SI) for each elbow. SI was defined as the distance between the centers of 2 circles drawn along the margins of the incisura trochlearis and the trochlea of humerus on mediolateral digital radiographic projections, normalized by the radius of the circle circumscribing the humeral trochlea. SI was compared between right and left elbows with and without pathology using a Wilcoxon test for paired data, and between normal and abnormal groups with a Wilcoxon test for unpaired data. Mismatch between ulnar curvature and curvature of humeral trochlea and radioulnar incongruency were also noted (Wilcoxon test). The intraobserver repeatability, correlation between SI and radioulnar incongruency, and between SI and mismatch elbow curvature were estimated with a Pearson's correlation coefficient.

RESULTS

Intraobserver repeatability of SI measurement was high (r = 0.97). Mean ± SD humeroulnar incongruity (SI) was greater in elbows with MCD (18.5 ± 6.6) than in the normal elbows (1.7 ± 2.0, P < 0.001). The difference between the diameters of the curvatures of the ulnar and humeral trochlea was greater in elbows with MCD (12.5 ± 4.4) than in the normal group (10.7 ± 4.1, P < 0.05). A moderate correlation was found between the degree of humeroulnar incongruity and a radioulnar step (r = 0.63); however, no correlation was identified between SI and the difference between the diameters of the curvatures of the ulnar and humeral trochleae (r = 0.14).

CONCLUSION

We propose a radiographic index to measure humeroulnar incongruity on mediolateral digital radiographic projections. This index (SI) supports the presence of humeroulnar incongruity in Labrador Retrievers with MCD. Further evaluation of its reproducibility and clinical importance are warranted. Although there is a moderate correlation between humeroulnar incongruity and radioulnar incongruency, causation has not been established.

Radiographic evaluation of osteotomized ulnar segments following arthroscopic treatment for canine medial coronoid disease

OBJECTIVE

To assess movement of ulnar segments radiographically, following proximal and midshaft ulnar osteotomy or ostectomy after arthroscopic treatment for dogs diagnosed with medial coronoid disease.

METHODS

Fragmentation and cartilage wear were treated arthroscopically and the presence of incongruity confirmed. Osteotomies were performed at the mid-point or proximal third of the length of the ulna. The distance of separation between the ulnar segments and the adjacent radius were measured and followed by serial radiographs postoperatively until healing had occurred.

RESULTS

Proximal oblique osteotomies located at one-third the length of the ulna were associated with the most movement of the ulnar segments, most notably of the proximal segment. Osteotomies or ostectomies performed in the middle demonstrated less segmental movement and on average, slightly longer time to heal. Movement of the ulnar segments in both groups occurred immediately, and then peaked at two to four weeks postoperatively, tending to plateau thereafter.

CLINICAL SIGNIFICANCE

Radioulnar incongruity is considered a facet of the aetiopathogenesis of canine medial coronoid disease. This creates abnormal loads and focal wear along the medial coronoid process. Performing an oblique osteotomy at a location measured at the proximal third of the length of the ulna allows increased movement of the proximal segment, which may result in unloading of the medial compartment. Performing an osteotomy or ostectomy distally dampens segmental movement due to constraint of the interosseous ligament. These findings suggest that a proximal oblique osteotomy at this location creates immediate favourable movement with low morbidity.

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.

Relationship between Radioulnar Incongruity of Elbow Joints and the Type of Fragmented Processus Coronoideus Medialis

The aim of the study was to find the difference between actual and anticipated frequencies of individual types of FCP (fragmented coronoid process) in relation to the extent of radioulnar incongruity. We evaluated the radiographs of elbow joints (n = 135) of dogs (n = 77) with arthroscopically (n = 109) or arthrotomically (n = 26) proven fragmented coronoideus medialis ulnae. Radioulnar incongruity was classified as a congruent joint (0-0.5 mm), moderate incongruity (0.6-2 mm) and marked incongruity (> 2.1 mm). In elbow joints without radiologically identifiable radioulnar incongruity (0-0.5 mm) significantly higher occurrence of fissured PCM (processus coronoideus medialis) was found (p < 0.01). In elbow joints with pronounced radioulnar incongruity (> 2.1 mm) we found significantly higher occurrence of FCP with a dislocated fragment (p < 0.001). The results of this study suggest the possibility of using the assessment of radioulnar incongruity from radiographs of elbow joints in mediolateral projection for specifying the X-ray diagnosis of FCP with regard to the type of FCP lesion.

Diagnostic imaging of canine elbow dysplasia: a review

Canine elbow dysplasia (CED) is a common developmental disorder of the cubital joint of dogs. CED is comprised of fragmented medial coronoid process (FMCP), ununited anconeal process (UAP), osteochondrosis (OC), and elbow incongruity. Multiple imaging modalities have been used to assess this complex of disorders and the severity of the pathologic changes. Radiography has been used as a surveying tool for assessment of CED for many years. Recently, alternate techniques and modalities have expanded our knowledge of CED and our clinical approach to this disorder. Nuclear medicine has been used to aid in localizing lameness to the elbow joint. Ultrasonography has proven helpful for imaging the soft tissue structures adjacent to the joint as well as superficial bone abnormalities, including visualization of FMCP. Computed tomography and magnetic resonance imaging are advanced imaging modalities that allow visualization of the elbow in multiple planes and into three-dimensional reconstructions, thus allowing lesions to be more accurately and comprehensively visualized. Assessment of elbow incongruity in particular has been benefitted by these advanced imaging techniques because of the importance of sagittal and dorsal plane imaging and reconstructions for accurately determining the relationships between radial and ulnar articular surfaces. Comparative studies using multiple techniques and imaging modalities with correlation to reference standards and patient outcomes will be vital to continued progress in this area.

Radiographic, Computed Tomographic, and Arthroscopic Evaluation of Experimental Radio-Ulnar Incongruence in the Dog

OBJECTIVE

To compare the diagnostic value of arthroscopy, computed tomography (CT), and radiography for evaluation of radio-ulnar incongruence (RUI).

STUDY DESIGN

Experimental evaluation of induced progressive RUI.

SAMPLE POPULATION

Cadaveric Labrador forelimbs (n=11).

METHODS

The radius was shortened by 1, 2, and 3 mm with a surgical model of RUI. RUI was scored on radiographs, CT (2 radiologists), and arthroscopy (2 surgeons) before and after each modification. The sensitivity and specificity of each modality were compared. The effects of arthroscope and elbow position on arthroscopy observations were evaluated. Agreement between surgeons, radiologists, and each imaging technique and the known status of the elbow was calculated.

RESULTS

Complete arthroscopic sessions had an averaged sensitivity of 94% and specificity of 81.9%. The ability to detect mild incongruity (1 mm step) was greater at the incisure than other locations (P<.001). The average sensitivity and specificity of radiography were 99.3% and 42.4%, and for CT were 85.05% and 45.8%, respectively. The average agreement between imaging techniques and the known status of the elbows was greater with complete arthroscopic sessions (89.75%) than radiography (70.1%) and CT (76.85%). Inter-investigator agreement was greater between surgeons scoring arthroscopic examinations (88.6%) than radiologists scoring CT studies (43.9%).

CONCLUSIONS

Evaluation of arthroscopic images allows sensitive and reproducible detection of experimental RUI, especially at the incisure. Arthroscopic evaluation of experimental RUI reached a higher diagnostic value than radiographs and CT images, because of its specificity and reproducibility.

CLINICAL RELEVANCE

The diagnostic value and reproducibility of arthroscopy may compare favorably with those of CT when evaluating RUI in dogs with elbow disease.

Effect of computed tomography display window and image plane on diagnostic certainty for characteristics of dysplastic elbow joints in dogs

OBJECTIVE

To test the effects of computed tomography (CT) image plane and window settings on diagnostic certainty for CT characteristics associated with dysplastic elbow joints (elbow joint dysplasia) in dogs and to provide optimal display guidelines for these CT characteristics.

SAMPLE POPULATION

CT images of 50 dysplastic elbow joints from 49 lame dogs and 10 elbow joints from 5 sound dogs.

PROCEDURES

CT image data were obtained in transverse, sagittal, and dorsal planes. Each plane was examined by use of 3 Hounsfield unit (HU) window settings. Two veterinary radiologists independently evaluated sets of CT images for evidence of 7 CT characteristics. Effect of elbow joint status, image plane, and window settings on diagnostic certainty for these CT characteristics was tested by use of a visual analogue scale.

RESULTS

Diagnostic certainty for abnormalities of the medial coronoid process (MCP) and radial incisure was highest in the transverse plane, subchondral defects or sclerosis of the trochlea humeri was highest in the dorsal plane, and joint incongruity was highest in the sagittal plane. Certainty for hypoattenuating subchondral defects or fissures was highest at 2,500 or 3,500 HUs, whereas certainty for subchondral sclerosis was highest at 1,500 HUs and lowest at 3,500 HUs.

CONCLUSIONS AND CLINICAL RELEVANCE

Diagnostic certainty for CT characteristics of elbow joint dysplasia in dogs was affected by image display variables. Diagnostic certainty for altered subchondral bone density was primarily influenced by window settings, whereas structural MCP abnormalities and joint incongruity were influenced most by image plane.

Fragmented coronoid process in the dog: is there a role for incongruency?

Fragmented coronoid process in the dog is a common yet frustrating and poorly understood condition. Elbow joint incongruency, which refers to malalignment of the joint surfaces of the elbow, has been proposed as a key factor in the pathogenesis of fragmented coronoid process, and various surgical procedures have been devised to treat the proposed incongruency. However, precise characterisation of incongruency present in cases of fragmented coronoid process has not been reported consistently. In this article, the literature relating to the pathogenesis of fragmented coronoid process, the role of incongruency and its implications are reviewed.

Computed tomography in small animals – Basic principles and state of the art applications

Since its clinical introduction, computed tomography (CT) has revolutionized veterinary medicine and is considered to be one of the most valuable tools for the imaging work-up of neurological, oncological and orthopaedic canine and feline patients. In small animals with acute trauma, particularly those involving complex anatomic areas such as the head, spine or pelvis, CT has been established as a standard imaging method. With the increasing availability of radiation therapy in veterinary medicine, CT has also become the principal tool to stage a tumour, assess response, and guide radiation therapy. The increasing availability of helical CT in veterinary medicine has allowed novel techniques such as spiral CT angiography and high-resolution CT. This review provides a brief overview of the historical and technical development of CT and literature reviews of the major clinical CT applications in small animals such as intracranial and extracranial lesions, the spine, the appendicular skeleton, and abdominal and thoracic diseases.

Computed Tomographic Evaluation of Canine Radioulnar Incongruence In Vivo

OBJECTIVE

To compare radioulnar incongruence (RUI) of normal canine elbows and elbows with arthroscopically confirmed medial compartment disease in vivo using systematic computed tomography (CT) measurements.

STUDY DESIGN

Prospective comparison of RUI measurements in normal and dysplastic canine elbows.

SAMPLE POPULATION

Right elbows of 25 medium-large breed, adult dogs with medial compartment disease and 9 medium-large breed, adult dogs with no elbow disease.

METHODS

Transverse CT images of proximal radioulnar articulation were reformatted to dorsal and sagittal planes. RUI in 3 locations of the forelimb's medial coronoid was measured. Arthroscopy confirmed diagnosis of medial compartment disease in the diseased group. RUI measurements of the diseased and normal elbows were compared.

RESULTS

Cumulative statistical analysis of RUI in all planes revealed no significant difference between the normal and abnormal elbows (P = .61). The abnormal elbows had negative mean RUI at the mid (P = .56) and cranial (P = .24) coronoid regions that were not significantly different from normal elbows and mean positive RUI at the base coronoid that was significantly greater than in normal elbows (P = .00082).

CONCLUSION

Canine elbows with established medial compartment disease do not have significant RUI at the medial coronoid region at the time of diagnosis when compared with normal elbows.

CLINICAL RELEVANCE

If RUI is a significant factor in the pathophysiology of medial compartment elbow disease in the dog, it does not appear to be present at the time of diagnosis of disease. Ulnar or radial osteotomies do not appear to be indicated for restoration of normal radioulnar articular surface alignment.