Assessment of the geometry of the cubital (elbow) joint of dogs by use of magnetic resonance imaging

Radiographic determination of humeroradial, humeroulnar, and radioulnar subluxation indices to quantify elbow incongruence in dogs confirmed to have medial coronoid disease

Medial coronoid disease and elbow incongruence are common orthopedic problems causing forelimb lameness in large breed dogs. Therefore, the objective of this retrospective clinical study is to radiographically quantify the incongruity of humeroradial, humeroulnar, and radioulnar joints in dogs with confirmed medial coronoid disease compared to controls. Sixty-six (93 elbows) control and 73 (113 elbows) diseased Labrador and Golden Retrievers were enrolled. Our objective was achieved by measuring the central humeroradial, humeroulnar, and radioulnar distances and calculating the corresponding subluxation index of each joint on the extended mediolateral elbow radiograph. The traditional radioulnar step was also measured on the same mediolateral projection. Variables were compared between control and diseased groups, and the significance level was P < .05. The central humeroradial, humeroulnar, and radioulnar distances and corresponding subluxation indices increased significantly (P ≤ .007) in elbows with confirmed medial coronoid disease compared to controls. Radioulnar step increased significantly (P < .0001) in diseased elbows. Elbow incongruence, manifested by increased humeroradial, humeroulnar, and radioulnar subluxation indices, appeared to be consistent with medial coronoid disease in Labrador and Golden Retrievers. An elbow with a humeroradial, humeroulnar, or radioulnar subluxation index >0.15, 0.10, or 0.14, respectively, or radioulnar step >1.4 mm, is more likely to be incongruent and may have a concomitant coronoid disease. However, future validation of the reported measurements is still warranted.

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.

Erosion of the medial compartment of the canine elbow: occurrence, diagnosis and currently available treatment options

Erosion of the medial compartment of the elbow joint refers to full thickness cartilage loss with exposure of the subchondral bone (modified Outerbridge grades 4–5) of the medial part of the humeral condyle (MHC) and the corresponding ulnar contact area. This finding may appear in the absence of an osteochondral fragment or a cartilage flap, or in combination with fragmentation of the medial coronoid process (MCP) or osteochondritis dissecans (OCD) of the MHC. With regard to the prognosis, it is important to diagnose these severe erosions. Imaging of cartilage lesions by means of radiography, ultrasonography, computed tomography or magnetic resonance imaging is challenging in dogs. In contrast, direct arthroscopic inspection provides detailed information about the cartilage.

The treatment of these severe erosions is difficult because of the limited regenerative capacity of cartilage and presumed mechanical or physical triggering factors. Several conservative and surgical treatment methods have been proposed to treat elbows with severe cartilage defects. However, due to irreversible loss of cartilage, the prognosis in these cases remains guarded.

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.

Influence of chondrodystrophy and brachycephaly on geometry of the humerus in dogs

Objective: To assess the geometry of canine humeri as seen on radiographs in chondrodystrophic dogs (CD) and brachycephalic dogs (BD) compared to non-chondrodystrophic dogs (NCD).

Methods: Mediolateral (ML) and craniocaudal (CC) radiographs of skeletally mature humeri were used (CD [n = 5], BD [n = 9], NCD [n = 48]) to evaluate general dimensions (length, width, canal flare, cortical thickness), curvature (shaft, humeral head, and glenoid), and angulation (humeral head and condyle). Measurements from CD, BD, and NCD were compared.

Results: Mean humeral length was shorter in CD (108 mm) compared to BD (184 mm, p = 0.001) and NCD (183 mm, p <0.001). Craniocaudal cortical thickness at 70% of humeral length and ML cortical thickness at 30%, 50%, and 70% of humeral length were less in CD compared to BD and NCD. Humeral shaft curvature was greater in CD (9.9°) compared to BD (6.7°, p = 0.023). The ratio of glenoid radius of curvature / humeral length was greater for CD (11.1%) compared to NCD (9.7%, p = 0.013). The ratio of humeral width / humeral length was greater for BD (29.4%) compared to NCD (26.2%, p = 0.043). The ratio of glenoid length / humeral length was greater in CD (18.0%) than BD (16.4%, p = 0.048) and NCD (15.6%, p <0.001).

Clinical significance: Bone proportions and curvature in CD differ from BD and NCD. Differences are minor and unlikely to have clinical significance.

Radiographic assessment of humeroulnar congruity in a medium and a large breed of dog

Elbow joint incongruity is recognized as an important factor in the development, treatment, and prognosis of canine elbow dysplasia. Elbow incongruity has been measured based on radiographic joint space widths, however these values can be affected by the degree of elbow joint flexion. Recent studies have reported radiographic curvature radii as more precise measures of humeroulnar congruity in dogs. The aim of this prospective observational study was to describe radiographic curvature radii measured from flexed and extended elbow radiographs for a sample of dogs representing a medium breed (Portuguese Pointing Dog) and a large breed (Estrela Mountain Dog). The curvature radii from the ulnar trochlear notch and humeral trochlea were measured in 114 mediolateral elbow extended radiographic views (30 Portuguese Pointing Dog and 27 Estrela Mountain Dog), and 84 mediolateral flexed views (22 Portuguese Pointing Dog and 20 Estrela Mountain Dog). The sampled animals' ages ranged from 12 to 84 months (34.6 ± 17.8 months). Good agreement was observed between curvature radii measurements for flexed vs. extended views in both breed groups. Ulnar trochlear notch curvature radii measurements were greater than humeral trochlea curvature radii measurements in both breed groups. Both curvature radii were greater in the large-breed dog group vs. the medium-breed dog group. Both breed groups had ulnar and humeral curves with similar typology. However, the large breed group had greater intermediate differences between the humeroulnar surface curvature radii. Results from this study supported the use of curvature radii as measures of humeroulnar congruity in mediolateral flexed elbow radiographs of medium and large breed dogs.

Direct magnetic resonance arthrography of the canine elbow

This study compares the effects of four dilutions of the gadolinium-containing contrast media (1:100; 1:400; 1:800; 1:1,200) administered to the elbow on the quality of magnetic resonance images. All the examined dilutions had a positive effect on image quality, and 1:800 was regarded as the optimal dilution of gadolinium for viewing the elbow because it imparted good contrast to the joint cavity without obliterating the contours of articular surfaces. Transverse, sagittal, and dorsal low-field magnetic resonance images were obtained in 24 canine cadaver front limbs. The musculus biceps brachii, m. triceps brachii, m. extensor carpi radialis, m. flexor carpi ulnaris, the articular surfaces, the medial coronoid process and the anconeal process of the ulna were well visualized by High Resolution Gradient Echo, XBONE T2 and Spin Echo T1 sequences in the sagittal plane. The biceps brachii, pronator teres, flexor carpi radialis, extensor digitorum communis, extensor carpi radialis, deltoid muscle and the articular surface of the medial condyle of the humerus were very well visualized by 3D SST1 and XBONE T2 sequences in the transverse plane. The triceps brachii muscle, extensor digitorum lateralis muscle, superficial digital flexor, deep digital flexor and the medial condyle of the humerus were very well visualized by the Spin Echo T1 sequence in the dorsal plane. This article describes for the first time the use of the gadolinium contrast agent administered to the canine elbow joint during magnetic resonance modality. Magnetic resonance arthrography can be a helpful visualization technique in treating canine soft tissue elbow injury.

Computed tomography and radiographic assessment of congruity between the ulnar trochlear notch and humeral trochlea in large breed dogs

OBJECTIVE

Assess the fit between the ulnar trochlear notch (UTN) and humeral trochlea (HT) in elbow radiographs and computed tomography (CT) images by measuring the curvature radii in normal joints.

METHODS

Mediolateral extended view (MLE) and CT were performed on 16 elbows from cadaveric dogs weighing over 20 kg. Curves were traced at the subchondral level from the UTN central ridge and the HT sagittal groove related to the UTN on ~132° joint extension. Curvature radii were achieved using appropriate computer software.

RESULTS

Intraclass correlation coefficient between MLE/CT measurements were statistically significant, with lower limits of a 95% confidence interval (CI) >0.75. The mean differences between MLE/CT measurements were -0.71 mm (95% CI: -0.97 to -0.45) for UTN and -1.04 mm (95% CI: -1.21 to -0.87) for HT. The UTN and HT curvature radii typology were similar, with maximum radius values at the starting point and two intermediate peaks. The UTN curvature radii were bigger than the HT radii, with the largest differences in the most proximal aspect of the joint and in the second intermediate peak.

CLINICAL SIGNIFICANCE

To the authors' knowledge, this is the first report on humeroulnar congruity through curvature radii evaluation. The software and methodology proposed enabled an adequate UTN and HT radii curvature assessment in MLE and CT images. Comparative studies in normal and dysplastic dogs of various breeds could better clarify the role of UTN and HT curvature radii in elbow incongruity and dysplasia.

Correlation between histopathologic, arthroscopic, and magnetic resonance imaging findings in dogs with medial coronoid disease

OBJECTIVE

To describe the magnetic resonance imaging (MRI), arthroscopic, and histopathologic changes in dogs with medial coronoid disease and to identify potential relationships between these findings.

STUDY DESIGN

Retrospective case series.

SAMPLE POPULATION

Twenty-five diseased medial coronoid processes (MCP) were collected from 19 dogs with a confirmed diagnosis of medial coronoid disease that were surgically treated by subtotal coronoid ostectomy. A reference group of normal MCP was collected from 9 dogs euthanatized for reasons unrelated to elbow disease.

METHODS

MCP specimens were evaluated by MRI using a novel grading scheme (all dogs), arthroscopy using a modified Outerbridge scheme (affected dogs only) and histopathology (all dogs).

RESULTS

The common histopathologic findings were subchondral microfractures, subchondral microfractures continuous with cartilaginous fissures, moderate to severe hypercellularity of the marrow space, trabecular bone necrosis, and articular cartilage degeneration. The severity of cartilage disease in the MCP was moderate to severe in most specimens, even in cases with minimal arthroscopic pathology. Three distinct patterns of bone marrow lesion (BML) were identified adjacent to the MCP, but there was no correlation between BML pattern and either histopathologic or arthroscopic findings. There was moderate correlation between modified Outerbridge scores and MRI scores. No correlation was identified between the histopathologic changes and either MRI or arthroscopic scores.

CONCLUSION

There was no significant correlation between the clinical scores and histopathologic changes. Ongoing improvements in the resolution of noninvasive imaging techniques will likely improve description and understanding of the MCP disease in dogs.

Magnetic resonance imaging of primary and concomitant flexor enthesopathy in the canine elbow

Flexor enthesopathy is a recently recognized elbow disorder in dogs and considered to be an important differential diagnosis for elbow lameness. Primary and concomitant forms of the disease have been previously described and treatments differ for the two forms. The goal of this prospective study was to compare magnetic resonance imaging (MRI) findings for dogs with primary flexor enthesopathy (n = 17), concomitant flexor enthesopathy (n = 23), elbow dysplasia alone (n = 13), and normal elbows (n = 7). Each elbow joint underwent MRI using the same low-field scanner. Sequences included transverse and sagittal T1-weighted (before and after IV contrast), transverse and sagittal T2-weighted, and dorsal STIR. For each elbow, MRI lesions were recorded based on a consensus of two observers unaware of group status. Magnetic resonance imaging lesions involving flexor tendons were found in 100% of clinically affected joints with primary flexor enthesopathy and 96% of clinically affected joints with concomitant flexor enthesopathy. Thickened flexor muscles were the most common lesions, followed by hyperintense tendon signal and contrast enhancement. Irregular, thickened medial humeral epicondyle, edema, and calcified body lesions were less frequently observed. Magnetic resonance imaging characteristics of flexor enthesopathy were not found in normal joints or those affected by elbow dysplasia alone. No significant differences in frequencies and details of individual MRI characteristics were found between primary and concomitant flexor enthesopathy groups. Findings indicated that MRI is a sensitive technique for detection of flexor enthesopathy lesions in dogs, however, MRI characteristics do not allow differentiation of primary versus concomitant forms of the disease.

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.

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.

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.