In Paget's disease of bone involving the proximal femur, the pathological stress fracture on the lateral (convex) cortex of the anterolaterally bowed femur (sabre tibia equivalent) is called a:

• A Banana fracture / lateral cortex stress fracture (incomplete fissure fracture) requiring prophylactic intramedullary nailing ✓
• B Looser zone
• C Pathological fracture through malignant degeneration
• D Insufficiency fracture at the medial cortex

Explanation

In Paget's disease, the weakened pagetic bone undergoes characteristic anterior bowing (particularly the femur and tibia — 'sabre tibia'). The lateral cortex of the bowed femur experiences maximum tensile stress; repeated micro-fractures form transverse cortical fissures on the lateral (convex) aspect — called 'banana fractures' (also 'fissure fractures' or 'lateral cortex stress fractures'). These incomplete fractures are at high risk of progressing to complete transverse fractures with minimal trauma. The management is prophylactic intramedullary nailing when fissure fractures are identified, combined with bisphosphonate therapy to suppress Paget's activity. Looser zones are the characteristic incomplete fractures of osteomalacia, not Paget's disease.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.