What Is an Acetabular Fracture?

The hip bone is composed of three parts: the sacrum, the ischium, and the pubic bone. There is a large and deep socket on the outer side called the acetabulum. The acetabulum is an important part of the hip joint. Because the hip joint is heavy and mobile, it is easy to be injured. And acetabular fractures can be caused by pubic sciatic or metatarsal fractures when pelvic fractures, and can also be caused by central dislocation of the hip joint.

Basic Information

English name: fracture of acetabulum
Visiting department: orthopedics
Common locations: hip joint

Common causes: Indirect and squeeze violence
Common symptoms: Early stage is local pain and limited movement of the hip joint, lower limb deformity and elastic fixation, etc.

Causes of acetabular fractures

Mostly caused by indirect and squeeze violence. It is common for a large femoral trochanter on one side to hit the ground when the human body falls from a height. At this time, the impact of the femoral head on the acetabulum can cause a non-displacement fracture of the acetabulum or a fracture of the inner wall of the acetabulum into the pelvic cavity. Violence along the longitudinal axis of the femur when flexing the hips and knees can also cause fractures of the posterior edge of the acetabulum. If the lower limbs are in the adducted position, in addition to causing acetabular fractures, posterior dislocation of the hip joint is prone to occur, and when the lower limbs are abducted, it can cause comminuted fractures of the acetabular top. In addition, crush injuries can also cause acetabular fractures.

Clinical manifestations of acetabular fractures

Early acetabular fractures are mainly manifested as local pain and limited mobility of the hip joint. If the femoral head is dislocated, it is associated with corresponding lower limb deformity and elastic fixation. When the central dislocation of the hip joint occurs, the degree of pain and dysfunction are not as good as the anterior and posterior dislocation of the hip joint, and the signs are not obvious. The severe dislocation can be manifested as shortened affected limbs.

Fractures of the acetabulum may be accompanied by massive pelvic hemorrhage, urethral or nerve damage, rupture of the pelvic ring and fracture of the ipsilateral lower limb.

Acetabular fracture examination

CT scan and fracture classification:

Fracture of posterior wall

On CT scan, the top surface of the acetabulum can show the comminuted fracture of the posterior upper edge of the weight bearing area, and the middle level of the acetabulum can show the fracture of the posterior edge of the acetabulum with defects. Fractures of the posterior edge of the acetabulum with defects can be shown in the middle of the acetabulum. For posterior column fractures, the top surface of the CT acetabulum showed a fracture line in a coronal direction, and the square area and the ischial tuberosity showed fractures in the middle of the acetabulum and the ischial tuberosity, respectively. No fracture was found in other levels of CT.

2. Anterior wall fracture

Fractures of the anterior acetabulum can be seen at the middle acetabular level, with no fractures at other levels.

3. Anterior column fracture

CT-related levels can show fractures of the anterior superior iliac spine, square area, and pubic branch respectively. Compared with anterior wall fractures, the fracture line of the anterior column fracture has a higher starting point and a direction of travel closer to the center of the acetabulum.

4. Transverse fracture

On the CT scan level, fractures can be shown at the lower level of the acetabular roof. There are no fractures at the level of the superior iliac spine to the top of the acetabulum and below the acetabular fossa, but usually transverse fractures are often accompanied by the lower acetabular and femoral head inward Bit.

5. Double-column fracture

CT acetabular top surface shows coronary fractures, middle acetabular surface shows square fractures, and pubic branch, ischial tuberosity, and sacrum fractures are shown at the pubic, ischial, and sacral levels, respectively.

6. Horizontal with posterior wall fracture

The top surface of CT acetabulum shows that the fracture line is sagittal, and there is no fracture in the medial square area of the acetabulum. This is a characteristic transverse fracture. The sagittal fracture is caused by the forward and backward displacement of the distal and proximal fracture segments. CT findings of posterior wall fractures were still present in patients with posterior wall fractures.

7. T-shaped fracture

In addition to transverse fractures with sagittal fractures of the acetabular top face, CT also shows fractures in square areas and sciatic branches. Posterior column with posterior wall fracture: CT shows coronal fractures and posterolateral margin fractures in the acetabular parietal area. The latter indicates that the fracture involves the weight-bearing area. Fractures in the posterior margin and square area of the acetabulum can be seen at the middle of the acetabulum. Ischia can be seen at the level of the ischial tuberosity. Nodular fractures, no fractures at other levels.

Three-dimensional CT reconstruction technology has been widely used in the diagnosis and classification of pelvic fractures. It can intuitively observe many information that cannot be displayed by X-rays, such as fracture displacement and location. It has outstanding advantages and is of great significance in guiding treatment.

Diagnosis of acetabular fracture

X-ray films, CT and 3D CT reconstruction examination can clearly diagnose the displacement of the fracture.

Treatment of acetabular fractures

Non-surgical treatment

Mild displacement of acetabular fractures can be treated conservatively. Conservative treatment can also be considered in the following two cases:

(1) Most of the acetabulum is intact and still matches the femoral head.

(2) After the two-column fracture is slightly displaced, a secondary match is formed: after the two-column fracture, all cartilage parts and the distant fracture piece together with the sacrum detached from the fracture block around the femoral head remain the same shape.

The purpose of non-surgical treatment is to prevent further development of displacement. Tibial tubercle traction can be used but the traction force should not be too large to prevent the femoral head from coming out of the acetabulum.

2. Surgical treatment

Most displaced acetabular fractures require surgery to achieve satisfactory reduction and fixation, reduce the incidence of post-traumatic arthritis, and facilitate early functional exercise.

Surgery should be performed two to three days to 10 days after the fracture. At this time, local bleeding has stopped and the fracture line is still clearly visible. It will be very difficult to reduce the growth of the epiphysis after 3 weeks.