A patient with both-column acetabular fracture shows the 'spur sign' on CT reconstruction. This sign indicates:
- A Femoral head impression fracture
- B Posterior wall comminution
- C No intact acetabular articular surface attached to the axial skeleton — pathognomonic of both-column fracture ✓
- D Marginal impaction of the acetabular dome
Correct answer: C. No intact acetabular articular surface attached to the axial skeleton — pathognomonic of both-column fracture
Explanation
The spur sign (or secondary congruence sign) is pathognomonic of a both-column acetabular fracture. It represents the intact superior portion of the posterior column (iliac wing fragment) projecting medially, visible on the iliac oblique view as a spur of bone. The key feature of both-column fractures is that no articular fragment remains attached to the axial skeleton (complete dissociation); all acetabular cartilage is on the free fragments. This means secondary congruence (femoral head remodeling the fragments) can sometimes be accepted without surgical fixation.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.