Acetabular Fracture Radiographic Evaluation

Acetabular fractures usually are evaluated with x-rays and CT scans. These x-rays are usually obtained out of traction. The iliopectineal line represents the anterior column line. The ilioischial line represents the posterior column line. The roof of the acetabulum can be seen in the AP view. The teardrop can be seen in the AP view. The anterior wall of the acetabulum can be seen in the AP view. The posterior wall of the acetabulum can also be seen in the AP view. Lets starts with the obturator view. In the obturator view, you can fully see the obturator foramen. The injured side will be up 45 degrees.  Oblique views usually show you a column and opposite wall. In the obturator view, you will see the anterior column and the posterior wall. You can also see the “spur sign.” The spur sign is pathognomonic for both associated BOTH column fractures. In the iliac view, the injured side is down 45 degrees and the good side is up. You will fully see the iliac wing. The posterior column and the anterior wall can be seen in the iliac view. It will tell us how to approach the injury and what type of fracture we have so that we can best approach the injury. CT scan will also show the joint congruity, the size of the fragment, if there is any trapped or impacted fragment. In general, the acetabular wall fracture is oblique and the column fracture is coronal. Transverse fracture of the acetabulum is sagittal or vertical. Transverse fracture of the acetabulum is NOT transverse. The rood arc is an angle between the vertical line through the femoral head and a line through the fracture site on all three views. The question is: did the fracture violate the weight-bearing dome of the acetabulum? You need to know whether you can treat the patient conservatively or surgically. If the fracture does violate the weight-bearing dome, then the patient will be treated surgically. Fracture of the acetabulum that does not violate the weight-bearing dome could be treated conservatively. The problem is that this measurement does not apply to the posterior wall or to the associated both column fractures. The fracture is stable if the fracture line exits outside the weight-bearing dome of the acetabulum and the fracture is usually greater than 45 degrees in the three views (AP, obturator oblique, and iliac oblique). 45 degrees is controversial! Dynamic stress fluoroscopy is used to evaluate the joint stability after an isolated small posterior wall fracture of the acetabulum. It is also used to test the stability of the fracture in a nondisplaced column fracture. If the fracture fragment is more than 50%, then the hip is definitely unstable. When there is a question about the stability of the hip, you should do examination of the hip under anesthesia, regardless of the size of the fracture fragment. The size of the fracture fragment is not a reliable indicator for hip stability. Even if the fracture fragment is less than 20%, you should still do the test. Get the C-arm, use AP and obturator views, flex the hip to 90 degrees and add axial force, and check the hip congruity and the subluxation of the hip. Check for opening of the medial clear space, which indicates instability of the posterior wall.

Acetabular Fracture Associated BOTH Columns

Associated BOTH column fracture is a fracture of both columns of the acetabulum. Both columns are separated from each other and from the axial skeleton, resulting in a floating acetabulum. This is the most complex type of acetabular fracture. The fracture type used to be called “central acetabular fracture.” This fracture pattern may be associated with central dislocation and no part of the articular surface remains attached to the axial skeleton. The acetabular fragments become free and rotate around each other. They may appear to maintain congruity to the femoral head. There is dissociation of the articular surface from the axial skeleton. Because of this secondary congruity, traction may be used in the treatment of associated both column fracture in the elderly. You will see the “spur sign” above the acetabulum on the obturator oblique view and this is diagnostic for associated BOTH column fracture. In the obturator view, you will find the anterior column (iliopectineal line) is disrupted and you will find the “spur sign.” The “spur sign” is the posterior inferior aspect t of the intact posterior ilium. Another feature of the associated BOTH column acetabular fracture is the Judet sign of the curved line. The Judet sign of the curved line occurs due to interruption by the fracture of the iliopectineal line. The curved line belongs to the greater sciatic notch and if after fixation anteriorly, the patient has a positive curved line sign, and then the posterior column is probably not reduced. The roof of the acetabulum is involved either totally or partially. When you see an x-ray and the roof of the acetabulum is in pieces, then this injury is probably an associated BOTH column fracture. You will see a coronal plane fracture through the iliac wing. In general see coronal for column fracture. If you have BOTH column fracture and there is an additional fracture going to the ilium then this is an associated BOTH column fracture. In CT scan, the fracture will be coronal. T-shaped fracture of the acetabulum is different from an associated BOTH column fracture of the acetabulum. In associated BOTH column fracture of the acetabulum, the fracture goes through the ilium. The acetabulum is floating and is disconnected from the axial skeleton. If you see extension of the transverse fracture of the acetabulum through the medial wall of the acetabulum and the fracture is going through the obturator ring, then this is a T-shaped fracture. The ilioinguinal approach is the main approach used to treat associated BOTH column fractures.

Acetabular Fracture T Shaped Fracture

T-shape facture of the acetabular is like a transverse fracture in addition to a vertical component fracture that is going towards the obturator foramen and is best seen on the obturator oblique view. If you see extension of the fracture through the medial wall of the acetabulum and the fracture is going through the obturator ring, then this is a T-shaped fracture. In general, you will have a superior iliac segment which is superior to the transverse fracture. There will also be an inferior ischiopubic segment which is split, usually by a vertical stem of a “T”. There will be two separate segments: the anterior articular segment (pubic) and the posterior articular segment (ischial). Usually the femoral head will displace medially and two caudal segments will rotate around the femoral head. Two approaches may be needed to fix this fracture. Because part of the articular surface remains attached to the iliac wing, then this fracture is not an associated BOTH column fracture. X-ray will show that the iliopectineal line and the ilioischial line are interrupted in addition to involvement of the obturator foramen or the presence of an ischial ramus fracture. By definition, this is a T-type fracture of the acetabulum. The inferior stem of the T-shaped fracture can be going in different directions. The fracture can be directed posteriorly, vertically, or anteriorly. CT scan will show the vertical line fracture, which is sometimes called the sagittal fracture. This represents the transverse part of the T-shaped fracture. Where do you see the vertical stem of the T-shaped fracture? If you see extension of a transverse fracture of the acetabulum through the medial wall of the acetabulum and the fracture is going through the obturator ring, then this is a T-shaped fracture. The vertical component of the fracture is best seen in an obturator oblique view. There are different patterns of different acetabular fractures which can be confusing. The first one is the transverse fracture of the acetabular and one can see the vertical or sagittal line. The second one is the T-shaped fracture. In the T-shaped fracture, one can see the sagittal fracture of the acetabulum with vertical fracture of the inner wall of the acetabulum. The third example is the posterior column and posterior wall fracture. It involves the inner wall but lacks the sagittal component of the transverse acetabular fracture pattern.

Lumbar Spine Transverse Process Fracture

In the lumbar spine, the transverse processes are covered by thick muscles. Fracture of the transverse process is rare. It may occur as an avulsion fracture due to strong contracture of the muscles. Injury may also be due to sudden extreme twisting, side bending or by direct impact to the process itself. The injury will not cause instability of the spine or spinal cord injury. Transverse process fractures are usually treated with a corset or brace, but not by surgery. Associated injuries may occur to the abdominal viscera, retroperitoneum, and the pelvis. lumbar spineThis is a minor injury caused by a major force. There is a frequent association with intra-abdominal injuries. If you can see the fracture on the x-ray, look for other injuries. This fracture may be missed on a routine x-ray. A CT scan is better at defining the fracture. A patient with a benign looking transverse process fracture would have associated significant injury to the back.  An L5 transverse process fracture in the he presence of a pelvic fracture is a predictor of pelvic fracture instability. Its presence should alert the clinician to this possibility. For example, an L5 transverse process fracture may be a sign of an unstable pelvis. It occurs due to an avulsion of the iliolumbar ligament.