Orthopaedics
Lower Limb Fractures
Lower limb fractures for MBBS and NEET-PG: neck of femur, intertrochanteric, femoral shaft, tibia and Weber ankle fractures with avascular necrosis and compartment risk, mapped to NMC OR2.10 to OR2.14.
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Lower Limb Fractures
Lower limb fractures for MBBS and NEET-PG: neck of femur, intertrochanteric, femoral shaft, tibia and Weber ankle fractures with avascular necrosis and compartment risk, mapped to NMC OR2.10 to OR2.14.
This chapter covers fractures of the hip, femur, tibia and ankle. It emphasises the anatomy that drives outcome, especially the fragile blood supply of the femoral head and the vulnerable soft tissue envelope of the tibia, and the treatment principles that separate the fractures that heal well from those that do not.
High-yield: Lower Limb Fractures
- The blood supply to the femoral head runs mostly retrograde up the neck, so a displaced intracapsular neck of femur fracture risks avascular necrosis.
- A displaced intracapsular neck of femur fracture in the elderly is usually treated with hemiarthroplasty or total hip replacement rather than fixation.
- An intertrochanteric fracture is extracapsular, unites well and is typically fixed with a dynamic hip screw.
- The Garden classification grades intracapsular neck of femur fractures and helps predict avascular necrosis.
- A femoral shaft fracture can lose a litre or more of blood into the thigh and is a recognised cause of fat embolism.
- Femoral shaft fractures in adults are usually treated with closed intramedullary nailing.
- A tibial shaft fracture is the commonest long bone fracture and, being subcutaneous, is a common site for open fractures.
- The tibia is a high risk site for compartment syndrome, so pain on passive stretch of the toes must be actively sought.
- Delayed union and non-union are more common in the tibia because of its relatively poor soft tissue cover and blood supply.
- Ankle fractures are commonly classified by the Weber system based on the level of the fibular fracture relative to the syndesmosis.
- A bimalleolar or trimalleolar ankle fracture is unstable and usually needs open reduction and internal fixation.
- A patellar fracture with an extensor lag or a palpable gap needs surgical fixation to restore knee extension.
- A distal femur or tibial plateau fracture is intra-articular and demands accurate reduction to prevent later osteoarthritis.
- In children, a fall causing a limp with a normal x-ray may hide a toddler fracture of the tibia or a growth plate injury.
Proximal femur fractures
- **Intracapsular neck:** Risks avascular necrosis. Displaced fractures in the elderly usually get arthroplasty.
- **Intertrochanteric:** Extracapsular, good blood supply, unites well, fixed with a dynamic hip screw.
- **Femoral shaft:** Significant blood loss and fat embolism risk. Intramedullary nailing in adults.
- **Tibia:** Commonest long bone fracture, frequent open injury, high compartment syndrome and non-union risk.
NMC competencies in this chapter
- **OR2.10:** Fractures of the proximal femur and their management
- **OR2.11:** Fractures around the knee including the patella and tibial plateau
- **OR2.12:** Fracture of the shaft of the femur and fat embolism
- **OR2.13:** Fractures of the tibia and fibula
- **OR2.14:** Ankle fractures and their classification
Frequently Asked Questions
Why does a neck of femur fracture risk avascular necrosis?
The femoral head is supplied by vessels that run up along the neck. A displaced intracapsular fracture tears these vessels, so the head can lose its blood supply and die.
How is an intracapsular fracture treated differently from an intertrochanteric one?
A displaced intracapsular fracture in an older patient is usually replaced with a hemiarthroplasty or total hip replacement, while an intertrochanteric fracture is extracapsular and heals well after fixation with a dynamic hip screw.
Why is the tibia a high risk site for compartment syndrome?
The leg has tight fascial compartments with limited room to swell, so bleeding and oedema after a tibial fracture can quickly raise pressure and cut off circulation.
What does the Weber classification describe?
It grades ankle fractures by the level of the fibular fracture relative to the syndesmosis, which helps predict stability and the need for surgery.
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