Evidence of the development of 'domain-restricted' expertise in the recognition of asymmetric motion characteristics of hindlimb lameness in the horse.

REASONS FOR PERFORMING STUDY: Visual assessment of horses' movements is subjective, affected by bias and dependent on the level of experience of the assessor. However, to date there are no data available on the ability of the human visual system to recognise (a)symmetry in moving objects. OBJECTIVES: To investigate, using visual lameness assessment, the limits of human perception and the ability of experienced and nonexperienced individuals to detect asymmetry in 2 moving objects simulating hindlimb lameness in the horse. METHODS: Twelve experienced individuals (equine and small animal clinicians), and 24 nonexperienced individuals (undergraduate veterinary students) were presented with computer simulations showing 2 'tuber coxae markers' created using data from both lame and nonperceptibly lame horses, as well as artificial data based on a sine wave. Individuals were asked to classify as symmetrical or asymmetrical, and then rank based on the grade of perceived asymmetry. Repeatability and learning effect were evaluated by repeating the tests on a subset of subjects. RESULTS: The threshold for detection of movement asymmetry was found to be approximately 25% difference in amplitude between the 2 moving objects for all individuals. There was no significant difference between experienced and nonexperienced individuals in the ability to detect asymmetry in the simulations based on artificial data. However, the percentage of correct answers was higher for experienced compared to nonexperienced individuals for simulations based on data from real lame horses. CONCLUSIONS: There was a significant difference between experienced and nonexperienced individuals in the ability to identify asymmetric movement based on the pattern seen in a lame horse, as opposed to an artificial pattern for which all individuals showed similar performance. POTENTIAL RELEVANCE: The study provides the basis for the development of computer simulations that could aid in training veterinarians in the diagnosis of lameness and, even, the objective assessment of expertise in this field.

Intra- and interobserver agreement in the interpretation of navicular bones on radiographs and computed tomography scans.

REASONS FOR PERFORMING STUDY: Criteria for the radiographic evaluation of navicular bones in horses have been published to standardise classification of radiographic signs. However, intra- and interobserver agreement have not been established. OBJECTIVE: To determine intra- and interobserver agreement in the evaluation of radiographic and computed tomographic (CT) navicular changes. It was hypothesised that: 1) intraobserver agreement would be better than interobserver agreement; 2) agreement would be better for CT than for radiography; and 3) pathological changes would be recognised with greater certainty with CT. METHODS: Radiographs and CT scans of 60 cadaver navicular bones were evaluated by 3 observers using published criteria. A subset of 30 studies was evaluated twice by one observer. Agreement was tested using the kappa statistic. Certainty about pathological changes was evaluated by giving the observers the option to choose 'not sure'. RESULTS: Agreement varied from poor to almost perfect for radiographic evaluation and from poor to substantial for CT evaluation. For radiographic evaluation mean interobserver agreement was fair, as it was for CT evaluation. For radiographic evaluation mean intraobserver agreement was moderate as it was for CT evaluation. Pathological changes were evaluated with greater certainty on CT scans compared to radiographs; however, this was not associated with improved agreement. CONCLUSIONS: Variations in classification of navicular lesions in radiographic and CT studies were considerable between and within observers and challenge the use of such studies for diagnostic and prognostic purposes. POTENTIAL RELEVANCE: The results of this study allowed the identification of evaluation criteria with sufficient precision to be useful for navicular bone evaluation.

Spectrum of computed tomographic findings in 58 canine elbows with fragmentation of the medial coronoid process.

OBJECTIVE: To describe in detail the computed tomographic findings in elbows of dogs with fragmentation of the medial coronoid process of the ulna. METHODS: Retrospective review of computed tomographic images of 58 elbows that had displaced medial coronoid process fragment(s), non-displaced medial coronoid process fragment or a stable fissure in the articular cartilage of the medial coronoid process at arthroscopy. RESULTS: Bone fragments were observed in 85 per cent elbows with a displaced fragment at arthroscopy, in 18 per cent elbows with a non-displaced fragment and in 29 per cent elbows with a stable fissure. Fissures in the subchondral bone were observed in computed tomographic images of 43 per cent elbows that had a stable fissure at arthroscopy. Abnormal shape, sclerosis and lucency affecting the medial coronoid process, subchondral sclerosis of the ulna and humerus, irregular radial incisure of the ulna and periarticular osteophytes were observed in a similar proportion in dogs regardless of the arthroscopic findings. Kissing lesions affecting the medial aspect of the humeral condyle were mainly associated with displaced fragments. Signs of joint incongruity were observed in dorsal and sagittal reconstructed computed tomographic images in 24 per cent elbows. CLINICAL SIGNIFICANCE: A wide range of abnormalities may be observed in computed tomographic images of dogs with fragmented medial coronoid process. Computed tomographic is moderately sensitive for detection of fragments.