## Analysis of Neck of Femur Fracture Complications and Management ### Classification and Vascular Anatomy Neck of femur fractures are classified as intracapsular (within the joint capsule) or extracapsular. The femoral head receives blood supply primarily from the medial and lateral femoral circumflex arteries, which enter through the retinacular vessels. Intracapsular fractures disrupt this delicate blood supply. ### Complication Risk: Displaced vs. Undisplaced **Key Point:** Displaced intracapsular fractures carry a significantly higher risk of avascular necrosis (AVN) compared to undisplaced fractures—up to 10–30% in displaced vs. 5–10% in undisplaced cases. **Clinical Pearl:** The degree of displacement and the patient's age are the two most important predictors of AVN risk. Younger patients have better collateral circulation but are more likely to suffer displaced fractures from high-energy trauma. ### Treatment Principles by Age and Displacement | Fracture Type | Age Group | Treatment | Rationale | |---|---|---|---| | Undisplaced intracapsular | Young (< 50 yrs) | Cannulated screws (in situ fixation) | Preserves femoral head; low AVN risk | | Displaced intracapsular | Young (< 50 yrs) | Cannulated screws or open reduction + internal fixation | Attempt to preserve femoral head; acceptable AVN risk | | Displaced intracapsular | Elderly (> 65 yrs) | Hemiarthroplasty or total hip arthroplasty | Avoids prolonged immobility; acceptable functional outcome | ### Why Option 2 (Hemiarthroplasty Contraindicated in All Elderly) is WRONG **High-Yield:** Hemiarthroplasty is **NOT** contraindicated in elderly patients with displaced intracapsular fractures—it is actually the **preferred treatment** in this group. The statement "contraindicated in all elderly patients" is false and overgeneralized. **Tip:** The choice between hemiarthroplasty and total hip arthroplasty in elderly patients depends on: - Functional status (THA preferred if high-demand, independent) - Cognitive status (THA may be better tolerated if compliant) - Comorbidities (hemiarthroplasty if high surgical risk) - Acetabular cartilage quality (THA if osteoarthritis present) Hemiarthroplasty remains a valid and commonly used option, especially in frail, low-demand elderly patients. ### Why the Other Options Are Correct **Option 0 (AVN more common in displaced):** TRUE. Displacement disrupts the already tenuous blood supply to the femoral head, increasing AVN risk substantially. **Option 1 (Cannulated screws for undisplaced young patients):** TRUE. In situ fixation with cannulated screws is the gold standard for undisplaced intracapsular fractures in young patients, preserving the femoral head. **Option 3 (Non-union due to precarious blood supply):** TRUE. Non-union is a recognized complication, particularly in intracapsular fractures, because the femoral head has a tenuous blood supply and is entirely intra-articular, limiting periosteal healing. ### Mnemonic: AVN Risk Factors in NOF Fractures **DISP** = **D**isplacement, **I**ntracapsular location, **S**evere (high-energy), **P**atient age (younger = higher AVN risk paradoxically due to mechanism, but better collateral in elderly). **Warning:** Do not confuse "hemiarthroplasty is preferred in elderly" with "hemiarthroplasty is the only option." Total hip arthroplasty is also acceptable in select elderly patients with good functional status.
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