A trochanteric fracture is a bone break affecting the upper region of the femur or thigh bone, where two bony prominences known as the greater trochanter and lesser trochanter are found. Several types of trochanteric fracture may occur, some of them concurrently. Intertrochanteric fractures are bone breaks between the two trochanters, while subtrochanteric fractures occur just below the trochanters, where the shaft of the femur begins. Trochanteric avulsion fractures are those in which a fragment of bone belonging to one of the trochanters breaks away from the femur.
The top portion of the femur bone joins with the pelvic bones to form the hip joint. Shaped like a ball, the head of the femur is the part that aligns with the acetabulum, a socket formed by the intersection of the ilium, ischium, and pubis bones of the pelvis. Angling downward and outward from the hip joint is the neck of the femur. The greater and lesser trochanters are found at the base of the femoral neck.
On the outside border of the bone, the greater trochanter forms a large prominence, while the lesser trochanter forms a small bump on the femur’s inside border a short distance below. These bony landmarks are significant because they are where the bone changes direction, with the shaft angling downward and inward from the base of the neck, and because they are sites of attachment for several muscles of the hip and thigh. In anatomy drawings of the upper femur, an imaginary line known as the intertrochanteric line is often included, bisecting the femoral head and neck and forming the mid-point between the greater and lesser trochanters.
A type of trochanteric fracture called an intertrochanteric fracture is one in which the bone break occurs perpendicular to the intertrochanteric line. It appears as a fissure between the two trochanters and may be partial or complete. Surgery is typically required to treat an intertrochanteric fracture.
Often accompanying this type of trochanteric fracture is an avulsion fracture of the greater or lesser trochanter. It tends to occur as a consequence of a vigorous contraction of an attaching muscle, such as the gluteus maximus or iliopsoas, that yanks a fragment of the trochanter away from the bone. An avulsion fracture may be treated with bed rest and may be accompanied by an injury to the attaching muscle tendon.
An additional type of trochanteric fracture is the subtrochanteric fracture. This fracture type tends to occur in the same direction as the intertrochanteric fracture but inferior to or below the trochanters. It can be a similarly severe femur fracture that requires surgical repair.