| Popis: |
In the paper by McLellan et al. (2009), the authors bring several key issues to the attention of the reader. They remind the reader that articular cartilage lesions can be difficult to diagnose without combining multiple imaging modalities with the ultimate articular exploratory tool of arthroscopy. A broader concept highlighted by this paper is the difficulty in diagnosing subtle conditions associated with the equine stifle in general. In this particular case report, the clinicians were suspicious that the observed lameness originated from the stifle joint. There was some mild effusion and the lameness was worse with upper limb flexion. However, the next step in an examination usually involves the desensitisation of nerves and/or the joint. In this case, the results of regional anaesthesia were inconclusive. Desensitisation of the nerves proximal to the tarsus did not improve the lameness, nor did intra-articular injection of anaesthetic agent. So where did that leave the clinicians? They had a lame racehorse and no diagnosis. They then turned to imaging. A routine radiographic study of the stifle was negative, while nuclear scintigraphy showed a focal and relatively intense region of increased radiopharmaceutical uptake (IRU) along the caudal aspect of the patella. Ultrasound of the area highlighted by the IRU led to suspicions regarding the health of the articular cartilage and arthroscopic surgery confirmed the presence of a lesion. This paper touches on the challenges facing clinicians attempting to diagnose the cause of lameness originating from the stifle joint. Effusion is one of the hallmark signs of stifle disease (Fig 1). In young horses, effusion often indicates the presence of an osteochondral defect of some sort. Most are present on the lateral trochlear ridge or as a subchondral cyst in the medial femoral condyle. In the mature horse, however, significant effusion in the stifle is less common. In fact, in most cases of stifle lameness affecting the mature athlete in our practice, there are no palpable abnormalities noted on the physical examination. Regional anaesthesia can also generate a variable response, as demonstrated in the case reported here. As a result, many clinicians turn to diagnostic imaging. |
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