2009 Radiology Exam - Musculoskeletal Case 1

• 7 year old, female spayed, Lab.
• HBC. Ambulates but painful on right pelvic limb manipulation.

The musculoskeletal section of the 2009 certifying examination was presented to the candidates as a PowerPoint presentation using jpeg images optimized to display the lesions of interest.

See images below. Click to enlarge.

Radiographic Findings:

• There is mild soft tissue swelling ventral to the sacrum and caudal lumbar region.
• There is a minimally displaced fracture of the right ilial body with multiple fissure lines. One fissure line extends to the mid dorsal portion of the right acetabulum.
• It was notable that the urinary bladder is well defined and abdominal serosal detail is normal in this patient with a history of HBC trauma.
• The patient has an incidental transitional vertebral segment at the lumbosacral junction. The segment is incompletely fused to the sacrum and the left transverse process articulates with the ilium at the SI joint.

Radiographic Diagnosis (Synthesis):

• Acute right ilial and acetabular fracture.
• Sublumbar soft tissue swelling consistent with hemorrhage from the fracture, or much less likely soft tissue swelling of other origin such as sublumbar lymphadenopathy.
• Incidental transitional lumbosacral vertebral segment.

Recommendations/Management:

• The articular nature of the right pelvic fractures is significant for the patient as the associated joint damage will lead to premature right coxofemoral degenerative joint disease.
• It was expected that the candidate would recommend additional imaging to further characterize the articular fracture. An additional “open leg” lateral oblique of the pelvis was provided to the candidate if they requested this view. This view confirms a single fracture line with a 1mm gap extends through the acetabulum. A CT exam of the pelvis, was also considered an acceptable recommendation.
• A recommendation of an abdominal ultrasound exam to confirm the nature of the sublumbar soft tissue swelling was also considered acceptable.

Candidate performance:

Most candidates had little difficulty in identifying the fracture and its significance. Several candidates failed to recognize or comment on the sublumbar soft tissue swelling or transitional segment. Some candidates were marked down for recommending inappropriate tests such as a positive contrast cystogram to rule out a ruptured urinary bladder, despite the normal appearance of the bladder and normal serosal detail.