How does one classify femoral neck fractures on the basis of their anatomy? How does this influence management?

These can be divided into intra-capsular or extra-capsular fractures with respect to their relationship to the capsule of the hip joint. Intra-capsular fractures have a high risk of avascular necrosis (AVN) of the femoral head and these fractures are treated with a femoral head replacement in most cases. Extracapsular fractures are internally fixed with devices such as the dynamic hip screw (DHS) or trochanteric nails.

What is the anatomical reason for AVN in intra-capsular fractures?

The greater part of the blood supply to the femoral head is via the retinacular vessels which in turn arise from the anastomosis of the medial and lateral circumflex femoral arteries. These retinacular vessels are closely related to the capsule and may be interrupted in cases of intra-capsular fractures, rendering the femoral head ischaemic.

What are the options in treating intra-capsular femoral neck fractures?

• Trial of conservative management with early mobilisation under supervision.

• Hemiarthroplasty (e.g. cemented, uncemented, bipolar)

• Internal fixation (e.g. DHS, cannulated screws)

• Total hip arthroplasty

In what circumstances would an intra-capsular fracture be treated with an internal fixation device?

In these fractures there is a high risk of AVN of the femoral head and femoral head replacement (hemiarthroplasty or THR) is a preferred mode of treatment. However in young patients (<65 years old) and/or those with undisplaced fractures (and therefore with little disruption of retinacular vessels) internal fixation may be contemplated.