History

A 6-month-old Duroc gilt intended for show purposes and weighing 136 kg (299 lb) was referred for a 1-month history of progressive left hind limb lameness and tarsocrural joint effusion. Intra-articular administration of corticosteroids had been performed 3 weeks previously by the referring veterinarian, which had reportedly aided in reducing joint effusion but had had no effect on the progressive lameness.

Physical examination findings were normal aside from marked effusion in the left tarsocrural joint and mild effusion in the right tarsocrural joint. Lameness examination revealed that consistent left hind limb lameness was present at the walk. Radiographs of the left (Figure 1) and right (not shown) tarsi were obtained.

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Plantarodorsal (A) and dorsolateral-plantaromedial oblique (B) radiographic views of the left tarsus of a 6-month-old Duroc gilt evaluated because of a 1-month history of progressive left hind limb lameness and tarsocrural joint effusion (lateromedial and dorsomedialplantarolateral views were also obtained but are not shown).

Citation: Journal of the American Veterinary Medical Association 238, 1; 10.2460/javma.238.1.39

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Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →

Radiographic Findings and Interpretation

Multiple views of the tarsi were obtained; however, the plantarodorsal and dorsolateral-plantaromedial oblique views allowed for the most optimal visualization of the lesions (Figure 2). A large oval osteochondral fragment and multiple small osteochondral fragments in the medial aspect of the left tarsocrural joint are evident in the left tarsus; there is also a large lucency in the subchondral bone of the articular surface of the medial trochlear ridge. On the dorsolateral-plantaromedial oblique projection, taken in an attempt to highlight the medial trochlear ridge of the talus, the lesion involves the entire proximal third of the medial trochlear ridge of the left talus.

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Same radiographic images as in Figure 1. A—One large oval and multiple small osteochondral fragments are present in the medial aspect of the tarsocrural joint along with a large subchondral lucency in the articular surface of the proximal aspect of the medial trochlear ridge of the talus (arrows). B—Notice that the lesion affects approximately the entire proximal third of the medial trochlear ridge of the talus (arrows).

Citation: Journal of the American Veterinary Medical Association 238, 1; 10.2460/javma.238.1.39

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A similar yet smaller and less defined lesion was radiographically identified on the medial trochlear ridge of the talus of the right tarsus (not shown). Radiographic findings of both tarsocrural joints were indicative of osteochondrosis dissecans (OCD), with lesions of the left tarsus being more advanced.

Comments

Arthroscopic exploration of the left tarsocrural joint was performed. Because of the anatomy of the porcine tarsocrural joint and the size of the largest osteochondral fragment, an arthrotomy was performed to facilitate removal of the fragment. By use of fluoroscopy, 18-gauge, 1-inch hypodermic needles were placed as a guide to determine the boundaries of the lesion as well as the surgical approach to best access the osteochondral fragment. A 5-cm-long incision was made over the plantaromedial aspect of the left tarsus, caudal to the medial collateral ligament and medial malleolus. Arthrotomy was followed by curettage and removal of multiple small osteochondral fragments over the articular surface of the medial trochlear ridge of the talus. Closure of the arthrotomy was achieved with 0 polyglactin 910 by placing a simple continuous pattern in the joint capsule and subcutaneous tissue, and a continuous intradermal pattern was used to draw the edges of the incision together.

A similar but smaller and less defined OCD lesion had been identified radiographically in the right tarsus; however, because of the absence of a history or current signs of lameness in the right hind limb, arthroscopic debridement of the right tarsocrural joint was not performed. A sterile pressure bandage was placed over the left tarsus immediately after surgery and changed 2 and 4 days later. Postoperative care consisted of morphine, ceftiofur sodium, and carprofen administration. The left hind limb lameness began to improve within days after surgery. Twelve weeks after surgery, the gilt was reported to be walking without any noticeable lameness or tarsocrural joint effusion.

Differential diagnoses for lameness and effusion in swine should include OCD, osteoarthritis, soft tissue trauma, fracture, and septic arthritis. Osteochondrosis dissecans is a common cause of lameness, an important clinical syndrome in swine that has detrimental effects on economic production and animal welfare.¹ Diagnosis of OCD is typically based on clinical signs and radiographic findings.² Radiographic changes associated with OCD include lucency of affected subchondral bone and osteochondral fragmentation. It has been well described that OCD is a result of a focal disturbance of endochondral ossification of the epiphyseal growth cartilage, but the etiology could be multifactorial.³ It has been shown that inherited factors have considerable effects on the prevalence, severity, and location of osteochondrosis lesions, and multiple traits could be involved; this should be taken into consideration if this gilt is eventually intended for breeding purposes.^1,3