Authors

Dr Keran Sundaraj MBBS MSc (Trauma) FRACS FAOA

Acetabular fractures involve a break in the socket of the hip joint. These fractures are uncommon and typically occur due to high-energy injuries, such as during a motor vehicle accident. Some of these fractures occur in lower-energy injuries, such as a fall. However, typically, this is seen in an older patient with weaker bones.

Anatomy

The hip is a ball and socket joint. The socket is formed by the acetabulum (part of the pelvis), and the ball is formed by the femoral head (upper end of the thigh bone).

The ball and socket are covered by a layer of articular cartilage, which provides a smooth surface for the bone ends to move against each other. However, this cartilage can be damaged due to the break in the underlying bone.

Ligaments connect bones, thus stabilising the hip joint in place. These may be damaged if the hip joint has fallen out of place.

Major nerves, blood vessels, and organs such as the bowel, bladder and reproductive system pass close to the pelvic bone. These are sometimes injured during an acetabular fracture.

Types of Fractures

Severity - this is based on several factors, including:

• The number and size of fragments.

• The amount of displacement (the gap) between fragments.

• The injury to the cartilage on both sides of the joint.

• The damage to the surrounding soft tissue, such as muscles, tendons, nerves and skin.

Pattern of injury

Fractures in the acetabulum can occur in:

• The anterior (front) part,

• The posterior (back) part,

• The wall (rim) of the socket, or

• A combination of these.

Imaging Tests

X-rays

• These are performed on arrival to the Emergency Department. They help to give a picture of the underlying bony structure.

• Specialised types of x-rays (Judet views) are sometimes used to view the complex architecture of the pelvis from different angles.

CT

• These provide a comprehensive three-dimensional view of the pelvis.

• They allow for a more detailed understanding of the bone, the displacement of the fragments and help decide on the appropriate treatment.

Treatment

Treatment is based on several factors:

• The specific fracture pattern.

• How much the bones are displaced.

• The patient's overall health.

Nonsurgical Treatment

This is recommended when:

• The fracture pattern is stable.

• The fracture is not significantly displaced.

• The patient is a high-risk candidate.

Treatment may include:

• Admission to hospital

• A period of modified weight bearing on the side that is affected.

• Walking aids to help with mobilising.

• Positioning aids such as splints to help the hip avoid certain positions.

• Pain killers.

• Blood thinners to prevent clots from forming in the veins of the legs.

Surgical Treatment

This is recommended when:

• The fracture pattern or the hip joint is unstable.

• The fracture is significantly displaced.

The goal of surgery is to alleviate pain and restore function in the long term. The timing of surgery may be delayed to improve a patient's overall condition and ensure the appropriate equipment and facilities are available. For unstable fracture patterns, traction, either via taping the leg or using a pin through a bone in the leg, may be used to help restore some temporary stability to the hip joint.

Open Reduction and Internal Fixation

This involves surgery to reposition the bone into normal alignment and stabilised it with plates and screws. These hold the fragments together while they heal. The incision for this may either be through the front, back or side of the hip. Occasionally, a combination of these approaches are used.

Total Hip Replacement

Sometimes the hip joint surface is so damaged that repair is unlikely to provide a good outcome in the long term. If this is the case, a new hip may be recommended to replace the damaged surfaces. Sometimes it may be necessary to allow the bone to heal (which may take months) and then perform a hip replacement.

Recovery

The majority of patients begin mobilising the day after surgery. Early mobilising is key to reducing medical complications after surgery, such as blood clots and pneumonia. A multidisciplinary (combined) team approach is taken between orthopaedic surgeons, medical doctors, physiotherapists, occupational therapists, and nursing staff.

Weight-bearing is often delayed for weeks. For some patients, this may mean up to 3 months on crutches. A walking aid, such as a walking stick, is sometimes required for a more extended period.

Even though weight-bearing may not be possible, movement is encouraged. This means getting out of bed and doing as much as is possible within the specific weight-bearing limitations. A physical therapist may help with directing patients. Over time, patients will learn exercises to build strength and endurance.

Patients may be transferred to a rehabilitation unit. Here the goal is to return patients back to their pre-injury condition.

Complications

Infections

Despite advances in surgical technique, this is a rare complication if surgery is performed. Treatment may vary depending on the extent of the infection. Short courses of antibiotics are used to treat superficial infections. Longer periods are used if the infection is deep such as next to the bone. These will usually require a surgical procedure to cleanse the wound.

Blood Clots

As mobility is limited after the injury, the normal flow of blood in the legs is impaired. This increases the risk of deep venous thrombosis (DVT). These sometimes break off and travel to the lungs, causing a pulmonary embolism (PE). This can be life-threatening. To try to prevent this complication, blood thinners are prescribed.

Posttraumatic Arthritis

Even when treated successfully, acetabular fractures damage the smooth articular surface of the hip joint. Over time, as this protective surface wears away, the joint becomes increasingly painful and stiff. In severe cases, a total hip replacement is required to relieve symptoms.

Sciatic Nerve Injury

The sciatic nerve is a large nerve that supports motions of the leg and foot. This may be damaged during the initial injury or the surgery. Injury often results in a 'foot drop' when the ankle or toes cannot be lifted from the floor. Nerves injuries can range in severity, and the recovery may take weeks or months. In some circumstances, there may be no recovery.

Heterotopic Ossification

This is a rare complication where bone may grow in the soft tissue around the hip joint. It is seen more commonly when surgery is performed. This may cause stiffness around the hip, rather than arthritis where the stiffness is within the hip joint. Sometimes surgical removal is required.

Avascular Necrosis

Blood supply to the hip joint may be disrupted due to the injury. Even if surgically repaired, there may be a lack of blood flow. This causes the joint end to lose its protective cartilage cap, and the joint surface becomes irregular. The surfaces are no longer smooth and free running, and this leads to stiffness and pain. Eventually, the joint wears away to such an extent that the bone upper end of the femur rubs on the acetabulum. This leads to arthritis. More information can be found here.

Outcomes

It may take 9 to 12 months for patients to recover from an acetabular fracture. In addition, as each patient's age, health, fracture pattern, and associated injuries are unique, treatment outcomes are highly variable.

What to Discuss with Dr Sundaraj

• How long can I expect off work?

• When can I start driving?

• Do I need to be screened for osteoporosis (weak bones)?

• When can I start physiotherapy?

• What is the likely outcome from this treatment?

• When do I need to come back?