What Is Your Diagnosis?

Michelle Nanfelt Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.

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 DVM, MS
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Lisa J. Zekas Department of Environmental and Radiological Health Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.

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Ross H. Palmer Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.

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 DVM, MS, DACVS

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History

A 3-year-old castrated male Husky was referred by a regional emergency clinic for treatment of pelvic fractures resulting from vehicular trauma. The dog was not willing to ambulate, and palpation of the right pelvic limb elicited signs of pain. Soft tissue swelling was detected around the right tarsal region. Crepitus and medial laxity were palpable when the right tarsal joint was simultaneously flexed and pronated, but were not detected while varus and valgus stresses were applied to the extended tarsal joint. Radiography of the pelvis revealed right sacroiliac luxation and fractures of the left pubis and ischium. Radiographs of the right tarsus were obtained during general anesthesia (Figure 1).

Figure 1—
Figure 1—

Mediolateral (A) and dorsoplantar (B) radiographic views of the right tarsal joint of a 3-year-old castrated male Husky evaluated because crepitus and instability were detected during simultaneous flexion and pronation of the joint.

Citation: Journal of the American Veterinary Medical Association 229, 3; 10.2460/javma.229.3.357

Radiographic Findings and Interpretation

An avulsion fracture of the lateral malleolus, widening of the talocalcaneal joint, and soft tissue swelling around the tarsus are evident on the dorsoplantar radiographic view (Figure 2). Cortical disruption compatible with a fracture of the talus and periarticular soft tissue swelling are evident on the mediolateral radiographic view. A small osseous fragment is apparent on the dorsal margin of the calcaneus.

Figure 2—
Figure 2—

Same radiographic views as in Figure 1. On the mediolateral (A) radiographic view, notice cortical disruption and stair-step deformity (black arrows) compatible with a fracture of the neck of the talus, a small osseous fragment on the dorsal margin of the calcaneus (white arrow), and periarticular swelling. On the dorsoplantar (B) radiographic view, notice widening of the talocalcaneal joint (black arrow), moderate soft tissue swelling, and an avulsion fracture of the distal extremity of the lateral malleolus (white arrow).

Citation: Journal of the American Veterinary Medical Association 229, 3; 10.2460/javma.229.3.357

Comments

Traditional varus and valgus stressed radiographic views with the tarsal joint held in extension were not helpful. Dorsoplantar flexed pronation and supination stressed radiographic views confirmed the presence of fractures of the talar neck and lateral malleolus and suggested that the medial collateral ligament (MCL) was intact (Figure 3). The radiographic diagnosis was oblique fracture of the talus with subluxation of the talocalcaneal joint and avulsion fracture of the lateral malleolus. Physical examination findings were the authors' rationale for obtaining dorsoplantar flexed pronation and supination stressed radiographic views.1 Pronation stress on the flexed tarsal joint applies tension to an isolated (tibiotalar short) component of the MCL. The MCL of the tarsal joint is a complex structure consisting of 3 distinct components.2 The tibiotalar short component, a stout ligament passing plantarodistally from the malleolus to the medial trochlea of the talus, is taut in flexion but somewhat lax in extension. In contrast to the tibiotalar short component, the long and tibiocentral components of the MCL span the talus and are taut in extension but lax in flexion.

Figure 3—
Figure 3—

Flexed pronated (A) and flexed supinated (B) radiographic views of the right tarsal joint confirming the presence of the talus fracture (small black arrows), indicating the lateral malleolus fracture, and suggesting the medial collateral ligament complex was intact. On the flexed supinated radiographic view, notice the talus fracture (black arrow), the lateral malleolus fracture, and a smaller fragment immediately distal to the lateral malleolus (white arrow) that was not readily appreciable on the mediolateral and dorsoplantar radiographic views.

Citation: Journal of the American Veterinary Medical Association 229, 3; 10.2460/javma.229.3.357

Detection of crepitus and instability only during pronation of a flexed tarsal joint suggests isolated disruption of the tibiotalar short component of the MCL.2 However, in the dog reported here, crepitus and instability were caused by the talar fracture. The authors suggest that flexion of the tarsal joint during palpation and radiography stabilized the trochlea of the talus by tensioning the intact tibiotalar short component of the MCL, whereas laxity within the long and tibiocentral MCL components spanning the talus permitted further displacement of the talar neck fracture.

Surgery was performed to repair the talar fracture and sacroiliac luxation. The integrity of the tibiotalar short component of the MCL was confirmed during surgical stabilization of the talar fracture. Eight weeks after surgery, healing of the pelvic and tarsal fractures, as determined by radiographs, was considered normal and the dog was ambulating with minimal lameness.

References

  • 1

    Miyabayashi T, Biller DS, Manley PA, et al. Use of a flexed dorsoplantar radiographic view of the talocrural joint to evaluate lameness in two dogs. J Am Vet Med Assoc 1991;199:598600.

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  • 2

    Aron DN, Purinton T. Collateral ligaments of the tarsocrural joint: an anatomic and functional study. Vet Surg 1985;14:173177.

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