2011 Radiology Exam - Musculoskeletal Case 1

Signalment: 8 year old male Labrador retriever
History: Acutely lame after jumping off porch

See images below. Click to enlarge.

Observation I – Lateral and DP views centered at the carpus
Major findings
• Intracapsular soft tissue swelling of the middle carpal and carpometacarpal joints
• Extracapsular soft tissue swelling of the metacarpus especially severe on the palmar aspect
• Multiple small mineral opacities dorsal to the middle carpal and carpometacarpal joints
• Mild hyperextension of the middle carpal joint
Minor findings
• Small mineral opacity immediately distal to the ulnar carpal bone
• Mild widening of the medial aspect of the middle carpal joint

Synthesis I
• Hyperextension injury of the carpus with resulting chip fractures of the dorsal aspect of the cuboidal bones of the carpus at the level of the middle carpal joint and carpometacarpal joint
• Severe soft tissue swelling of the palmar carpus and metacarpus with likely injury to the supporting soft tissue structures of the palmar carpus and metacarpus
• Suspect avulsion fracture of the palmarodistal aspect of the ulnar carpal bone and suspect loss of integrity of the collateral ligaments of the carpus

Management
• Stress radiographs to evaluate integrity of the collateral ligaments of the carpus and supporting soft tissue structures of the palmar carpus and metacarpus

Observation II – Stress radiographs
• Widening of the medial aspect of the middle carpal joint
• Severe hyperextension of the carpus at the level of the middle carpal joint with overriding of the dorsal aspect of the proximal and distal rows of cuboidal bones of the carpus in the area of fractures and widening of the palmar aspect of the middle carpal joint

Synthesis II
• Loss of integrity of the medial collateral ligaments of the middle carpal joint
• Loss of integrity of the stabilizing ligaments of the palmar aspect of the middle carpal joint

Management
• Surgical stabilization/arthrodesis

All candidates recognized the initial radiographic abnormalities of swelling and dorsal chip fractures. Successful candidates recognized the need for stress imaging to evaluate for soft tissue integrity of the carpus. Candidates were expected to request specific stess views which were provided on request and candidates received only views specifically requested. Candidates that failed the case did not recognize the need for additional imaging.