AVN following Femoral Neck Fracture : Wheeless' Textbook of Orthopaedics

- See:
- Avascular Necrosis of Femoral Head:
- Blood Supply to Femoral Head & Neck:
- Non-Union following Femoral Neck Frx;

- Discussion:
- when femoral neck frx occurs, intraosseous cervical vessels are disrupted;
- incidence of AVN in undisplaced fractures is 11%;
- only 1/3 of patients with AVN will require additional surgery where as 3/4 patients with non union will require reoperation;
- risk of AVN generally corresponds to degree of displacement of the fracture of the femoral neck on the initial radiographs;
- minimally displaced femoral-neck frx:
- is at low risk (< 10%) for osteonecrosis if displacement of the fracture remains unchanged;
- displaced frx:
- incidence of AVN following hip frx is may be > 80% in displaced frx;
- most of retinacular vessels are disrupted;
- femoral head nutrition is then dependent on remaining retinacular vessels and those functioning vessels in the ligamentum teres;
- Prevention:
- positioned achieved at reduction is significant factor in development of AVN & subsequent late segmental collapse;
- valgus & rotatory malposition are known to affect foveal blood supply;
- nails in superior (or lateral) aspect of femoral head can inadvertently interrupt lateral epiphyseal vessels that supply most of blood to the femoral head;
- whether early hip joint capsulotomy might reduce the incidence of AVN remains controverisal;
- timing of surgical fixation:
- it remains controversial as to whether early fixation of femoral neck frx will decrease risk of AVN;
- references:
- Avoidance of avascular necrosis of the femoral head, following fractures of the femoral neck, by early reduction and internal fixation.
- Delayed internal fixation of fractures of the neck of the femur in young adults. A prospective, randimsed study comparing closed and open reduction.
- Delayed fixation of displaced femoral neck fractures in younger adults.