## Vascular Anatomy and Pathophysiology of Intracapsular NOF Fractures ### Why Option 0 (Index) is INCORRECT **Key Point:** The PRIMARY blood supply to the femoral head is from the **MEDIAL femoral circumflex artery (MFCA)**, NOT the lateral femoral circumflex artery. - **Medial FCCA (primary):** Supplies 80% of the femoral head via lateral epiphyseal vessels that ascend along the femoral neck within the joint capsule. - **Lateral FCCA (secondary):** Supplies only 20% of the femoral head; its contribution is minimal. - **Intracapsular fractures** disrupt the lateral epiphyseal branches of the MFCA, leading to ischaemia and AVN. **High-Yield:** Confusion between medial and lateral FCCA is a classic NEET PG trap. Remember: **Medial = Major**. ### Why the Other Options are CORRECT | Statement | Evidence | |-----------|----------| | **Non-union Risk** | Intracapsular fractures are bathed in synovial fluid, which inhibits callus formation. Poor blood supply + synovial immersion = 10–15% non-union rate. | | **Garden Classification** | Grades I–IV; Grades III–IV are displaced and have worse prognosis. | | **AVN Risk by Displacement** | Undisplaced: AVN ~10%; Displaced: AVN ~30%. Displacement disrupts the remaining blood supply. | **Clinical Pearl:** A fracture that disrupts the lateral epiphyseal branches of the MEDIAL FCCA is the reason intracapsular NOF fractures are so prone to AVN. This is why young patients with displaced intracapsular fractures may still develop AVN even after successful internal fixation. **Mnemonic:** **MFCA = Main For femoral head** (Medial Femoral Circumflex Artery). [cite:Rockwood & Green's Fractures in Adults Ch 53]
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