Clinical, radiographical and pathological aspects of ununited medial coronoid process of the elbow joint in dogs

An ununited medial coronoid process was found in the region of the medial ulnar articular rim of seven elbow joints in four Persian stray dogs in a survey of joint disease in dogs. The clinical, radiographical and pathological aspects of this condition are described and discussed.     

On the weight-bearing function of the medial coronoid process in dogs

The shape of and proportions between the surface areas of the medial coronoid process (MCP) and the fovea of the radial head were determined in 88 juvenile dogs and 146 adult dogs grouped as giant, large, mid-sized, chondrodystrophic, or small dogs. Thereby, the longitudinal (length) and transverse (width) extension of the MCP and fovea of the radial head have been measured. Original values were used to describe changes of the parameters attributed to growth. Normalized values (i.e. values expected in case of a width of the fovea of the radial head of 20 mm) were used to determine potential differences between constitutional types. All original values increased during growth (P < 0.05) except for the width and length of the MCP in chondrodystrophic and small breeds. Normalized values revealed a proportional decrease in width and length of the MCP during growth (P < 0.05) compared with the radial head. In adults, the normalized MCP was widest in giant dogs followed by large, mid-sized, small, and chondrodystrophic breeds. The MCP was also longest in giant dogs but shortest in large and chondrodystrophic dogs with those of large dogs being significantly (P < 0.05) shorter than those in giant, mid-sized and small dogs. Present results suggest that a deficiency in length-growth of the MCP--which has been present especially in large dogs--results in smaller humeral contact areas and decreased weight-bearing capacity of the MCP. Because loading forces acting on the MCP increase with body weight, the condition noted in large dogs might increase the risk of fragmentation of the MCP in these.     

Evaluation of biomarkers for osteoarthritis caused by fragmented medial coronoid process in dogs

The aim of the present work was to evaluate whether concentrations of the carboxy-terminal cross-linked fragment of type II collagen (CTX-II), the activities of matrix metalloproteinase-2 and -9 (MMP-2/-9) and Myeloperoxidase (MPO) in canine synovial fluids (SF) can reflect structural alterations of articular cartilage in dogs with fragmented medial coronoid process (FMCP). Elbow joints with FMCP underwent radiographic and arthroscopic examination. Commercially available assays were used to analyze SF for CTX-II concentration and MMP-2/-9 activity. MPO activity was measured by o-dianisidine-assay. The MMPs were further evaluated by zymography. CTX-II concentration and MMP-2 activity showed age-dependent trends in controls. Increased enzyme activities of MPO and MMP-2/-9 were found in diseased dogs. MMP-9activity seems suitable to underline the subjective assessment of the degree of cartilage damage. These initial data of the study suggest that MPO and MMP-2/9 may be used as objective biomarkers in the diagnosis of canine osteoarthritis due to FMCP.     

Prevalence of fragmented medial coronoid process of the ulna in lame adult dogs

Over a period of three years, a diagnosis of fragmented medial coronoid process of the ulna was confirmed by arthroscopy in 263 dogs, in 69 of which both elbow joints were affected, giving a total of 332 affected joints; 39 of the joints were also affected by osteochondrosis dissecans of the trochlea of the humerus. More than half of the dogs (51.7 per cent) were over one year old when first examined. In 259 (78 per cent) of the joints there were radiographic changes of secondary osteoarthrosis of different severity, but the other 73 (22 per cent) had no signs of osteophytosis except for a mild sclerosis. Among these 73 there were 14 joints in 13 dogs between 19 and 36 months old and 11 joints in 10 dogs over three years old. A further 12 joints in 11 dogs over three years old showed only mild arthrosis. In five of the 11 joints of the dogs over three years old which had no radiological signs of arthrosis, the fragment was already dislocated. Among the dogs over 18 months old with no arthrosis and the dogs over three years old with mild arthrosis, the most commonly affected breeds were the Bernese mountain dog, rottweiler and boxer.     

Radiographic diagnosis and surgical management of fragmented medial coronoid process in dogs

The diagnosis of fragmented (ununited) medial coronoid process was made in 21 dogs, with 10 dogs having bilateral lesions. Ten of these dogs were presented to surgery. The diagnosis of fragmented medial coronoid process was made in young and middle-aged large- and giant-breed dogs with a history of intermittent or persistent lameness. Diagnosis was based on history as well as results of clinical examination and radiographic study of both elbows. Concomitant elbow lesions seen with fragmented medial coronoid processes were ununited anconeal process and osteochondritis dissecans of the medial humeral condyle. Avulsion of the medial epicondyle and posteromedial supracondylar ridge of the humerus were thought not to have occurred in these cases. Instead, dystrophic ossification of the synovial membrane and periosteal proliferation on the medial epicondyle and posteromedial supracondylar ridge had taken place. It was concluded that, with a questionable radiographic diagnosis of fragmented medial coronoid process, exploratory arthrotomy may be necessary to confirm the diagnosis. Without surgery, the eventual outcome of fragmented coronoid process is degenerative joint disease. Even with degenerative joint disease, however, clinical improvement was seen following removal of the fragment of the medial coronoid process.     

Evaluation of elbow incongruency using reconstructed CT in dogs suffering fragmented coronoid process

OBJECTIVES: A retrospective study was undertaken to evaluate elbow joint congruency in dogs suffering fragmented coronoid process (FCP). METHODS: Based on clinical, radiographic and computed tomographic (CT) examinations, elbows were divided into control and FCP groups. Standardised CT reconstructions were formatted in the frontal and sagittal planes. Humeroradial and humeroulnar joint space measurements were obtained from the Images and incongruencies were calculated by comparing the two measurements. RESULTS: Forty-two FCP and 29 control elbows were identified. No incongruencies were noted at the coronoid base. At the level of the coronoid apex, FCP elbows exhibited a significant radioulnar incongruency compared with controls (P < 0.0001), though incongruency was not identified in all cases. Comparing FCP and control elbows at the level of the apex, the humeroradial joint space was increased in FCP elbows (P = 0.0006) whereas no difference was noted in the humeroulnar space. CLINICAL SIGNIFICANCE: This study supports the hypothesis that joint incongruency is associated with FCP in dogs, though is not present in every case at the time of diagnosis. The precise mechanism of development of this incongruency cannot be determined from these data.     

Histomorphometry of fragmented medial coronoid process in dogs: a comparison of affected and normal coronoid processes

OBJECTIVE: To determine if fatigue microdamage is associated with fragmented medial coronoid process (FMCP). STUDY DESIGN: Prospective study. ANIMALS: Thirty-eight dogs were admitted for subtotal coronoid ostectomy as treatment for FMCP. Surgical specimens of medial coronoid process (MCP) were retrieved from treated dogs. Normal MCP were collected from 5 age- and breed-matched dogs and 2 age-matched research beagles that were euthanatized for reasons other than elbow disease. METHODS: MCP specimens from affected elbows were classified into 4 groups based on disease severity. Specimens were bulk-stained for microdamage using 1% basic fuchsin, embedded in polymethylmethacrylate and sectioned at 130 microm. Specimens were evaluated using epifluorescent microscopy (425-440 excitation, 475 nm barrier filter) for diffuse damage (D.DX), osteocyte loss, and porosity. Cartilage thickness was evaluated using bright field microscopy. Qualitative observations were also made. RESULTS: MCP specimens from affected elbows had increased D.Dx, increased osteocyte loss, and greater porosity than normal groups. Specimens classified as severe FMCP (Classes 3, 4) had the most fatigue microdamage. Some Class 1 specimens, defined as having no visible fissuring of the articular cartilage (AC), had large microcracks in trabecular bone. CONCLUSIONS: Accumulation of subchondral fatigue microdamage, is associated with MCP fragmentation. Fissuring occurs in the subchondral bone before gross fibrillation of articular cartilage develops. CLINICAL RELEVANCE: Accumulation of fatigue microdamage in the MCP is important in the pathogenesis of FMCP. The underlying cause of this microdamage accumulation must be identified before treatment plans that will prevent further osteoarthritis of the elbow joint can be designed.     

Magnetic resonance arthrography of the cubital joint in dogs affected with fragmented medial coronoid processes

OBJECTIVE: To evaluate efficacy of intra-articular injection of gadolinium tetra- azacyclododecane tetraacetic acid (gadolinium-DOTA) for delineating fragmented medial coronoid processes (FMCP) and lesions on the medial aspect of the humeral condyle (MAHC). SAMPLE POPULATION: 14 cubital joints in 9 dogs. PROCEDURE: Magnetic resonance imaging (MRI) was performed with and without intra-articular injection of a solution of 2 mmol of gadolinium-DOTA/L. Arthrographic images obtained after injection of contrast medium were compared with those obtained without contrast medium. Evidence of contrast medium around or in the medial coronoid process and infiltration of contrast medium in subchondral bone lesions was recorded. Twenty-four hours after imaging, arthroscopy was performed, and lesions detected were correlated with results of MRI. RESULTS: An abnormal coronoid process was diagnosed in 13 of 14 joints. A fragmented process (free) was seen in 7 of 14 joints; nondisplaced mineralized medial (in situ) coronoid processes were evident in 4 joints; and nondisplaced unmineralized medial coronoid processes were evident in 2 joints. Lesions on the MAHC were diagnosed in 4 of 12 joints. In 5 joints, a hyperintense signal resulted from contrast medium that infiltrated between the fragmented process and ulna. In 2 joints, contrast medium did not infiltrate completely around the process and was stopped by an isointense structure (ie, abnormal cartilage). Subchondral bone lesions were enhanced by use of contrast medium. CONCLUSION AND CLINICAL RELEVANCE: Use of arthrography enabled us to identify FMCP easily, but did not provide important additional information about changes on the medial coronoid process, compared with MRI performed without contrast medium.     

The prevalence of medial coronoid process disease is high in lame large breed dogs and quantitative radiographic assessments contribute to the diagnosis

Medial coronoid process disease is a common leading cause of thoracic limb lameness in dogs. Computed tomography and arthroscopy are superior to radiography to diagnose medial coronoid process disease, however, radiography remains the most available diagnostic imaging modality in veterinary practice. Objectives of this retrospective observational study were to describe the prevalence of medial coronoid process disease in lame large breed dogs and apply a novel method for quantifying the radiographic changes associated with medial coronoid process and subtrochlear‐ulnar region in Labrador and Golden Retrievers with confirmed medial coronoid process disease. Purebred Labrador and Golden Retrievers (n = 143, 206 elbows) without and with confirmed medial coronoid process disease were included. The prevalence of medial coronoid process disease in lame large breed dogs was calculated. Mediolateral and craniocaudal radiographs of elbows were analyzed to assess the medial coronoid process length and morphology, and subtrochlear‐ulnar width. Mean grayscale value was calculated for radial and subtrochlear‐ulnar zones. The prevalence of medial coronoid process disease was 20.8%. Labrador and Golden Retrievers were the most affected purebred dogs (29.6%). Elbows with confirmed medial coronoid process disease had short (P < 0.0001) and deformed (～95%) medial coronoid process, with associated medial coronoid process osteophytosis (7.5%). Subtrochlear‐ulnar sclerosis was evidenced in ～96% of diseased elbows, with a significant increase (P < 0.0001) in subtrochlear‐ulnar width and standardized grayscale value. Radial grayscale value did not differ between groups. Periarticular osteophytosis was identified in 51.4% of elbows with medial coronoid process disease. Medial coronoid process length and morphology, and subtrochlear‐ulnar width and standardized grayscale value varied significantly in dogs with confirmed medial coronoid process disease compared to controls. Findings indicated that medial coronoid process disease has a high prevalence in lame large breed dogs and that quantitative radiographic assessments can contribute to the diagnosis.     

The surgical treatment of osteochondritis dissecans and ununited coronoid process in the canine elbow joint

The case details of ten dogs with osteochondritis dissecans of the medial condyle of the humerus and seven dogs with ununited coronoid process are presented. Seventeen dogs were treated surgically and the medial approach to the elbow is described.     

Use of a radiographic scoring technique for the assessment of dogs with elbow osteochondrosis

A retrospective study was made of 335 dogs with elbow osteochondrosis that had been seen at the Royal Veterinary College in 1977 to 1987. The most commonly affected breeds were the labrador, retriever and rottweiler. Males were affected more often than females. The condition was bilateral in 50 per cent of cases and the peak age for the onset of lameness was four to six months. In rottweilers, the lesions found at exploratory arthrotomy were predominantly abnormalities of the coronoid process, while in retrievers and labradors lesions most commonly affected the medial humeral condyle or the coronoid process. A scoring system for grading the standard projection (lateral and postero-anterior) radiographs was devised and the score was correlated with the lesion found at surgery. Some cases were reviewed radiographically and any alteration in the degree of periarticular arthrosis, seen as an increase in radiographic score, was noted. The exact extent of the lesion found at surgery was recorded diagrammatically in 65 cases. It did not prove possible to predict from the radiographic score the nature and extent of the lesion and no correlation could be found between the radiographic score [and clinical degree of lameness. The scoring system did have some merit for reviewing cases because an increase in score indicated the extent to which joint changes had advanced.     

Use of a flexed dorsoplantar radiographic view of the talocrural joint to evaluate lameness in two dogs.

A flexed dorsoplantar radiographic view of the talocrural joint was a useful additional view to diagnose abnormalities of the lateral trochlear ridge of the talus of 2 dogs. This view outlined the subchondral bone of both trochlear ridges of the talus and the apposing cochlea tibiae of the distal portion of the tibia. The tarsus was flexed at the level of the talocrural joint, and an x-ray beam was centered on the joint. With this additional view, fractures of the lateral trochlear ridge were readily diagnosed. This view would help to demonstrate osteochondral lesions of the lateral trochlear ridge.     

A specific oblique radiography, and treatment, of a medial coronoid process fracture.

Acute traumatic fracture of the medial coronoid process is rarely reported and has previously only been described in three dogs to date. A three-year-old Schapendoes was presented for an acute non weight-bearing lameness. The definitive diagnosis of a medial coronoid process fracture was delicate and based on the disto-medial proximo-lateral oblique radiographic view (Di35M-PrLO). The surgical removal of the fragment was performed using a medial arthroscopic approach. The outcome was rapidly favourable. Lameness disappeared and the follow-up radiographs three months later revealed minimal reactions of osteoarthrosis.     

Use of radiographic measurements in the evaluation of dogs with medial patellar luxation

This prospective study used radiographic techniques to evaluate the inclination, Norberg, quadriceps and femoral varus angles, and the patellar position in dogs with developmental medial patellar luxation. The study also compared these measurements pre- and post-operatively to determine how they were affected by surgical procedures. Eighteen dogs with unilateral or bilateral luxation were used, and 4 groups were established according to luxation grade. Except for the quadriceps angle, there was no difference among the groups preoperatively. Significant differences for the quadriceps angle were observed between Grades 1 and 3, and between Grades 2 and 3. The Norberg and femoral varus angles and the patellar position showed no changes between pre- and postoperative groups. However, measurements of the preoperative quadriceps angle and postoperative inclination angle may be useful for evaluating dogs with grade-3 luxation. Further studies using other imaging techniques are required in dogs with severe grade-4 luxation due to the difficulty in obtaining a good radiographic position.     

Joint angle, moment and power compensations in dogs with fragmented medial coronoid process

Fragmented medial coronoid process (FMCP) is the most common cause of forelimb lameness in juvenile medium and large breed dogs; however methods of assessing the disruption to their gait remain subjective. The purpose of this study was to objectively quantify the mechanical disruptions to gait in dogs with arthroscopically confirmed unilateral FMCP. Seven dogs underwent full inverse dynamic analysis at the time of diagnosis. Kinematic and force data were collected from both forelimbs at trot. Stance phase joint angles, net joint moments and net joint powers were calculated using custom software. There were gross differences in kinetic and kinematic patterns between FMCP affected and compensating forelimbs. Stance time was 0.24 sec on the lame side and 0.26 sec on the compensating side. The shoulder and the elbow were more flexed at ground contact, and elbow, carpal and MCP joints had smaller ranges of motion on the lame side. Net joint moments were significantly reduced (P < 0.05) in the elbow, carpal and MCP joints of the FMCP affected limb. Net joint powers were likewise significantly smaller (P < 0.05). However, the overall moment and power patterns persisted. Total limb support moment was significantly smaller on the affected side (P < 0.05). Total limb power was significantly reduced on the affected side (P < 0.05) being most affected in its propulsive phase in the second half of stance. Inverse dynamic analysis of this clinical condition is an objective means by which to assess the mechanical disruption to gait.