A 72-year-old woman with osteoporosis falls on her right hip while getting out of bed. She presents with severe hip pain, external rotation, and shortening of the right lower limb. X-ray confirms a neck of femur fracture. What is the most common type of neck of femur fracture based on anatomical location?

Explanation

## Anatomical Classification of Neck of Femur Fractures Neck of femur (intracapsular) fractures are classified into three types based on their location along the femoral neck: ### Classification by Location | Type | Location | Frequency | Blood Supply Risk | |------|----------|-----------|-------------------| | **Subcapital** | Just below the femoral head | **~65–70%** | **Highest risk of AVN** | | **Transcervical** | Mid-neck, at the narrowest point | ~20–25% | Intermediate risk | | **Basicervical** | At the base of the neck | ~10–15% | Lowest risk of AVN | **Key Point:** Subcapital fractures are the **most common** type of intracapsular neck of femur fracture, accounting for approximately 65–70% of cases. This is well established in standard orthopedic references including Campbell's Operative Orthopaedics and Apley's System of Orthopaedics and Fractures. ### Why Subcapital Is Most Common 1. **Anatomical vulnerability**: The subcapital region, immediately below the femoral head, is subject to the greatest bending moment during a fall, concentrating stress at the head-neck junction. 2. **Osteoporosis**: Age-related trabecular bone loss is most pronounced in the subcapital region, making it the weakest point in elderly patients. 3. **Fall mechanics**: A fall onto the greater trochanter in an elderly osteoporotic patient transmits force directly to the subcapital region. ### Clinical Significance **High-Yield:** Subcapital fractures carry the **highest risk of avascular necrosis (AVN)** of the femoral head because the retinacular vessels (branches of the medial femoral circumflex artery) that supply the femoral head run along the femoral neck and are most vulnerable to disruption at the subcapital level. **Clinical Pearl:** The Garden classification (I–IV) is used to assess displacement and stability in intracapsular fractures. Undisplaced fractures (Garden I–II) have better prognosis and lower AVN rates than displaced fractures (Garden III–IV). Subcapital fractures are graded using this system to guide management (internal fixation vs. hemiarthroplasty vs. total hip replacement). *Reference: Apley's System of Orthopaedics and Fractures, 9th ed.; Campbell's Operative Orthopaedics, 13th ed.*