Basicervical femoral neck fractures are classified by AO/OTA as 31B3.
The fracture starts at the neck-trochanter junction laterally.
These fractures are uncommon injuries.
These are extraarticular but may be intracapsular fractures.
The blood supply to the femoral head is threatened because the displacement may disrupt the blood vessels leading to the femoral head. The more vertical the fracture line is after reduction, the more unstable it becomes because of the shearing forces acting on the fracture.
The blood supply of the femoral head
The vascular anatomy varies, but in 60% of patients, the medial and lateral femoral circumflex arteries originate from the profunda femoris artery (1).
Most of the blood supply of the femoral head comes from the medial femoral circumflex artery (2), which gives rise to three or four branches, the retinacular vessels (3). These run posteriorly and superiorly along the femoral neck in a synovial reflection until they reach the cartilaginous border of the head. The obturator artery gives rise to the vessels within the ligamentum teres (4). The medial and lateral circumflex arteries may anastomose, but the principal blood supply of the head originates from the medial circumflex artery and its branches, especially the ascending ones.
In the AP view, there is a disruption of the medial and lateral cortical line and a vertical fracture line.
In this case, the lateral view shows loss of version and a gap in the anterior cortical line.
3-D CT imaging is highly recommended to understand the morphology of the fracture and comminution.