Acetabular Fractures

Acetabular fractures are usually caused by a force applied to the femur which is
translated to the acetabulum.
In young adults, acetabular fractures are due to high energy injuries, primarily
motor vehicle accidents, fall from a height, motorcycle accidents, and pedestrians
hit by cars. The majority of patients are evaluated for and have associated injuries
that require initial evaluation of the multiple-trauma patient using ATLS protocols.
There are also a minority of patients, which are elderly, and suffer relatively minor
trauma causing acetabular fractures. If hip pathology is noted, 45° Oblique X-ray
views and CT scan of the pelvis should be taken.

Anatomy of the Acetabulum:

The acetabulum is made up of the fusion of the ileum superiorly, the pubis
inferiorly, and the ischium, posteroinferiorly. The acetabulum faces lateral,
inferior, and anterior in anatomical position. The articular surface of the
acetabulum is covered by hyaline cartilage and is an inferiorly incomplete cup.
This acetabular notch leads into the acetabular fossa and is covered by the
transverse acetabular ligament forming a tunnel that the foveolar artery
transverses. This artery supplies the head of the femur. The blood supply to the
acetabulum is via the acetabular artery, which is a branch of the anterior branch
of the obturator artery. The external surface of the acetabulum is covered with a
fibrocartilage lip called the acetabular labrum. The hip joint, which is made up of
the articulation femoral head and the acetabular labrum, is surrounded by several
ligaments. Anteriorly, the iliofemoral ligament (Y ligament of Bigelow) and the
pubofemoral ligaments stabilize the joint and prevent hyperextension and
excessive abduction. Between these two ligaments exists the iliopectineal bursa.
Posteriorly, the iliofemoral ligament and the ischiofemoral ligament prevent
hyperextension. Posterolateraly, there is a protrusion of the synovial sac, which is
of little clinical significance. The capsule of the joint surrounds the articular
surfaces and extends to within 1 cm of the distal end of the femoral neck.
















Diagnosis of Acetabular Fractures:

The diagnosis is made radiographically.

AP View


Landmarks to visualize

1) Iliopectineal line

2) Ilioischial line

3) Radiographic "U" 4) Acetabular dome (roof)

5) Anterior acetabular lip

6) Posterior acetabular lip

7) Iliac wing 8) Obturator foramen



Obturator Oblique View

This view profiles the anterior column of the acetabulum and the posterior rim.
The obturator foramen is seen in its largest dimension.





















Iliac Oblique View

The greater and lesser sciatic notches are seen and show any involvement of the
posterior columns of the acetabulum. The anterior rim is profiled and the iliac wing
is seen in its largest dimension.






















CT Scan

The CT scan is useful for fractures of the sacrum, quadrilateral surface, and
intraarticular free fragments. Also, the orientation of the fracture can be seen.
However, fractures may appear more comminuted than they actually are

Types of Acetabular Fractures:

The classification of acetabular fractures has been described by Letournel and
Judet in 1981. This classification aids in deciding which surgical approach to
undertake. The classification is shown in the following figure.






































After imaging and classification an operative approach must be decided upon.
The Kocher-Langenbeck approach is used for posterior wall, posterior column,
anterior column, transverse, T-shaped, associated posterior column and posterior
wall, and associated transverse and posterior hemitransverse fractures. The
Ilioinguinal approach is used for anterior wall, anterior column, and associated
anterior and posterior hemitransverse fractures. Both column fractures is
approached using the ilioinguinal or extended iliofemoral approach. The anatomy,
radiographic findings and operative approach are summarized in the table below.

Goals of Treatment:

Restore motion to the hip, mobilize the patient, and avoid post traumatic arthritis.

Treatment options:

Non-operative treatment considered with non-displaced acetabular fractures,
transverse fractures, and minimally displaced two-column fractures. Percutaneous
Treatment may be chosen for appropriate fracthres.

Urgent Surgical Treatment:

Urgent surgical treatment is indicated for patients with acetabular fractures and
anterior or posterior hip dislocation that cannot be reduced by closed methods.
Otherwise, a 2-5 day delay is acceptable +/- traction on affected leg.

Complications Associated With Surgical Repair of Acetabular Fractures:

1) Sciatic Nerve Palsy
Sciatic nerve palsy is caused by either initial trauma or retraction of the nerve
during a posterior surgical approach to the acetabulum.

2) Heterotropic Bone Formation

Myositis ossificans (heterotropic bone formation) usually occurs after the
extended iliofemoral approach. This can be minimized by the use of Indomethacin
or low-dose irradiation therapy post-operatively. If heterotropic bone forms and it
inhibits motion of the hip, removal of the ectopic bone may be attempted 12-18
months after initial surgery when there is a decreased likelihood of recurrent bone
formation.

3) Infection

The incidence of wound infection can be minimized by careful manipulation of soft
tissues, use of profuse  irrigation, perioperative use of antibiotics and hemostasis.

4) Thrombophlebitis

To minimize the risk of thrombophlebitis, a patient may be fitted with compression
stockings and sequential compression devices. Also, pharmacalogical therapy
may be used for anticoagulation.

5) Avascular Necrosis of the Femoral Head

The Foveolar artery and circumflex arteries may be transected during trauma
causing Avascular Necrosis

6) Post Traumatic Arthritis

Post Traumatic Arthritis is caused by altered anatomy, biomachanics and initial
trauma to the cartilage of the hip joint.

Summary and Conclusion:

The patient that enters the emergency room with acetabular fracture need
general resuscitation. If minimal displacement occurs, reduction is congruous, or
the patient is inoperable, he/she can be treated in a closed fashion. If the patient
has significant displacement or dislocation, closed reduction under anesthesia
should be tried. If this does not succeed, open reduction and internal rotation
should be initiated. Following a concise and well thought out algorithm should, in
most cases, achieve a good result.

References

Brown, D.E., Neuman, R.D., "Orthopedic Secrets." Philadelphia: Hanly & Belfus;
St. Louis: Mosby, c1995.

Hoppenfeld, S., DeBoer, P., "Surgical Exposures in Orthopaedics. The Anatomic
Approach." Philadelphia: Lippincot, c1994.

Hughes, S.P.F., D'aBenson, M.K., and Colton, C.L., "Orthopaedics: the Principles
and Practice of Musculoskeletal Surgery and Fractures." Edinburgh; New York:
Churchil Livingston, 1987.

Letournel E., "Acetabular Fractures: Classification and Management." Clinical
Orthopaedics and Related Research. 151:81, 1980.

Mallon, W.J., McNamara, M.J., Urbaniak, J.R., "Orthopedics for the House Officer."
Baltimore: William & Wilkins, c1990.

Moore, K.L, "Clinically Oriented Anatomy." Baltimore: Williams & Wilkins, c1992.

Turek, Samuel L., "Turek's Orthopaedics, Principles and Their Application. -- 5th
ed." Philadelphia: Lippincot, c1994.