A 32-year-old man sustains a comminuted fracture of the femur in a motor vehicle accident. Regarding the early and late complications of long bone fractures, all of the following are recognized complications EXCEPT:

## Complications of Fractures: Timing and Pathophysiology ### Early vs. Late Complications **Key Point:** Fracture complications are classified by timing — early (within days to weeks) and late (weeks to months/years). Understanding this temporal relationship is crucial for recognition and management. ### Analysis of Each Option | Complication | Timing | Pathophysiology | Correct? | |---|---|---|---| | **Fat embolism syndrome (FES)** | Early (24–72 hrs) | Mechanical release of marrow fat + biochemical injury from free fatty acids; classically occurs with long bone fractures | ✓ Yes | | **Volkmann's contracture** | Late (weeks–months) | Sequela of compartment syndrome → muscle ischemia → fibrosis and contracture of forearm flexors | ✓ Yes | | **Avascular necrosis (AVN)** | Late (months–years) | Disruption of blood supply to bone; develops over time as necrotic bone is resorbed and replaced | ✗ **NOT immediately** | | **Pulmonary embolism (PE)** | Early–intermediate (days–weeks) | Thromboembolism from immobilized limb; risk peaks in first 2 weeks post-fracture | ✓ Yes | **High-Yield:** Avascular necrosis is a **late complication** that develops over **months to years** after fracture, not immediately. It requires time for the necrotic bone to undergo creeping substitution and structural collapse. ### Why AVN Is Not Immediate 1. **Necrotic bone is initially structurally intact** — radiographs may appear normal in the first weeks. 2. **Revascularization and resorption take time** — creeping substitution occurs over months. 3. **Collapse and symptoms emerge later** — typically 6–12 months or longer post-injury. **Clinical Pearl:** AVN is most common after femoral neck fractures (disruption of lateral femoral circumflex artery) and scaphoid fractures (retrograde blood supply). Early recognition of risk factors (displaced fractures, delayed treatment) allows preventive intervention. **Mnemonic — Early Fracture Complications (FVPE):** - **F**at embolism - **V**olkmann's contracture (from compartment syndrome) - **P**ulmonary embolism / **P**ressure sores - **E**arly infection (open fractures) **Warning:** Do not confuse the *timing of injury* (fracture occurs now) with the *timing of complication onset* (AVN develops later). The question asks which is a recognized complication — AVN is recognized, but it is NOT immediate.