What is Acetabular Fractures?
Acetabular fractures, or breaks in the hip socket, usually happen to young people involved in high-speed injuries. Since seatbelt use became mandatory, we’ve seen a significant decrease in these fractures — now only about 3 out of every 100,000 people experience them. However, there’s been an increase in these fractures caused by falls of less than 10 feet, probably due to the increase in bone-weakening conditions like osteopenia and osteoporosis.
Little has changed since a significant research paper in 1993 by Letournel and Judet that still serves as the “gold standard” for treatment today. One of the major improvements has been the introduction of a procedure called percutaneous fixation for certain types of fractures.
The anatomy of the area involves a bone composed of the pubis, ischium, and ilium at the triradiate cartilage. The top part of the hip socket’s surface, known as the weight-bearing dome, is critical. Blood supplies the external surface through the superior gluteal artery, inferior gluteal artery, obturator artery, and medial femoral circumflex. The internal surface receives blood supply from the fourth lumbar, iliolumbar, and obturator arteries.
The hip socket can be thought of as an upside-down Y shape with a thick section of bone connecting it to the sacroiliac (SI) joint, called the sciatic buttress. The hip socket is divided into an anterior and posterior column. The anterior column contains the front part of the iliac wing that is continuous with a pelvic brim, the superior pubic ramus, and the front part of the hip socket surface. The posterior column begins at the top of the greater sciatic notch, includes the greater and lesser sciatic notches, and also includes the ischial tuberosity.
What Causes Acetabular Fractures?
Fractures in the acetabulum, a part of your hip, often occur from high-impact incidents and can often be accompanied by injuries to other parts of the body. These fractures can cause significant health issues because they can damage the cartilage in your hip and can lead to a severe form of arthritis in the future.
In extensive studies, it has been found that half of the patients who suffered an acetabulum fracture also had associated injuries: about a third had injuries to another part of their body, most commonly to the lower body; one in five had a head injury; nearly one in five had a chest injury; 13% had nerve damage; 8% had an abdominal injury, 6% had genitourinary (related to the urinary and reproductive organs) issues, and 4% had a spinal injury.
Even fractures that only affect the acetabulum can often require a blood transfusion—up to 35% of cases in one study. Doctors also need to assess whether the sciatic nerve, a major nerve extending from the lower back to the back of each leg, has been injured upon patient arrival. When there’s an injury to this nerve, it often affects the peroneal division, a part of the nerve that helps control foot and toe movement. And an injury to this part of the nerve can lead to foot drop, a condition where it’s difficult to lift the front part of your foot.
Risk Factors and Frequency for Acetabular Fractures
These injuries typically result from high-speed car accidents, falls from high places, and extreme sports. The frequency of these injuries has stayed consistent over the past few years, with about 3 cases per 100,000 people each year. Regardless, the number of fractures due to car accidents has remained unchanged, while falls from less than 10 feet seem to be causing more of these injuries. Furthermore, the average age of patients with these fractures appears to be rising.
- Most of these injuries are caused by high-speed car crashes, falls from heights, and extreme sports.
- The rate has remained stable, with around 3 cases per 100,000 people each year.
- The number of such fractures from car accidents has not changed.
- There has been an increase in the number of fractures caused by falls from less than 10 feet.
- The average age of patients with these fractures is also increasing.
Signs and Symptoms of Acetabular Fractures
Your first step in a trauma situation should be the standard trauma evaluation and resuscitation procedures. It’s important to figure out how the injury happened as it can help decide the best treatment. A full body check should be done to look for other injury signs. You need to thoroughly check the musculoskeletal system, particularly the skin and peripheral nerves. Also, inspecting the soft tissue can help detect a possible Morel-Lavalle lesion.
- Start with standard trauma evaluation and resuscitation protocols
- Determine the cause of the injury to guide treatment
- Perform a full body check for other signs of injury
- Do a thorough review of the musculoskeletal system, especially peripheral nerves and skin
- Check the soft tissue for a possible Morel-Lavalle lesion
Testing for Acetabular Fractures
To diagnose a broken acetabulum, i.e., the socket of the hip joint, one can typically start with an X-ray. However, a CT scan is often required if the patient has other injuries, as it provides a more detailed image than a standard X-ray. In the case of fractures, CT scans can better assess the fracture’s size, location, orientation, the presence of fragments within the joint, and other relevant details.
The initial X-ray usually includes both a front view of the pelvis and what are called Judet views: “obturator oblique” and “iliac oblique.” These different shooting angles help identify six important landmarks on the pelvic image, which further help in classifying the fracture pattern. These landmarks include the iliopectineal and ilioischial lines, the teardrop, and the anterior, posterior and the roof of the acetabulum. While the “teardrop” is just a radiographic finding, not an actual anatomic structure, it helps visualize certain aspects of a fracture.
The iliopectineal and ilioischial lines represent the anterior and posterior columns of the pelvis, respectively. CT scans have made the identification and classification of acetabulum fractures easier. In some cases, dynamic stress X-rays can also be used to evaluate hip stability, especially when there’s a fracture-dislocation involving the back wall of the acetabulum.
The most commonly used classification for acetabulum fractures, known as the Letournel system, groups fractures into five basic patterns and five associated patterns. The basic patterns include posterior wall, posterior column, anterior wall, anterior column, and transverse fractures.
Associated patterns include combinations of different fracture types. These involve fractures of the posterior column and wall, transverse and posterior wall fractures, anterior and posterior fractures, T-type fractures, and “both columns” fractures where the acetabulum has completely disconnected from the skeleton. These classifications help doctors to understand the nature and severity of the fracture and, consequently, to decide the best approach to treatment.
Treatment Options for Acetabular Fractures
Most fractures affecting the acetabulum, or hip socket, require a surgical procedure called open reduction and internal fixation. However, there are a few instances where non-surgical treatment may be suitable. Non-operative treatments might be considered for certain stable fractures that do not affect the key weight-bearing part of the hip socket, and fractures where the intact part of the socket can still maintain stability. These include some specific types of lower-positioned fractures and some where a measurement called a ‘roof arc’ is higher than 45 degrees. A CT scan can help identify which fractures might not need surgery by examining the top part of the socket. If no fracture lines are identified in this area, and the displacement is less than 2 mm, non-surgical management may be feasible.
Those managed non-surgically typically require bed rest initially, followed by foot-flat partial weight bearing as soon as they’re comfortable. Regular x-rays are taken over the first few weeks to monitor healing progress, leading to full weight-bearing by 6 to 12 weeks once the fracture has healed sufficiently. If the fracture indicates surgery is necessary but the patient can’t have the operation, they may need traction for an extended period.
Surgical treatment may be needed for fractures that cause hip joint instability, have bone or soft tissue trapped within the joint, or when non-operative treatment does not provide a satisfactory outcome. In such cases, possible options include surgery to replace the hip or percutaneous fixation, a minimally invasive procedure that is becoming increasingly popular.
Percutaneous fixation is a procedure performed using x-ray guidance and is particularly useful in situations when patients are unable to tolerate more invasive surgery. The patient might be lying on the back or side, and the surgeon uses a guidewire to fix the fracture, adjusting the position according to x-ray images. Depending on the fracture’s location, the wire might be placed either posteriorly or anteriorly.
Surgery is usually performed 3 to 5 days after injury, with longer delays potentially resulting in poorer outcomes. There are a few situations in which emergency surgery might be needed, including persistent or irreducible hip dislocation, worsening nerve damage, blood vessel injury, open fractures, and fractures of the femoral neck on the same side.
Surgical approach is chosen based on fracture type, time since injury, and where the fracture is most displaced. Common approaches include Kocher-Lagenbeck (for posterior fractures), ilioinguinal and iliofemoral (for anterior fractures). In some cases, the surgeon might use an extended iliofemoral technique which can access all areas of the hip socket, and is often used for delayed treatment.
Following successful reduction, the fracture fragments are secured, and the entire structure is reinforced using buttress plates. This may be done with screws alone in certain young, healthy individuals; however, osteopenic bone and wall fractures typically require use of buttress plating as well.
What else can Acetabular Fractures be?
Generally, with the use of modern CT scans, you shouldn’t mix up acetabulum (hip socket) fractures with other types of fractures. Other fractures that may look similar include fractures to the pelvic ring and the upper part of the thigh bone. In older patients who have fallen with less force and suffered fractures, doctors need to be careful about excluding a fracture due to disease.
What to expect with Acetabular Fractures
The outlook for those suffering from fractures of the acetabulum, or the hip socket, has generally been negative due to the high level of energy associated with the injury and the presence of accompanying injuries. However, surgical methods such as open reduction, where the bone is physically realigned, and internal fixation, where the bone is secured using internal devices, have improved the outlook.
The prognosis largely depends on several factors such as the fracture pattern, with T-shaped fractures having the worst outlook, and the condition of the hip at the time of injury. Other factors include damage to the femoral head (the ‘ball’ that fits into the hip socket), how well the hip is reduced (returned to its normal position), and the stability of the joint after treatment.
After treatment, the most reliable indicators of long-term outcome are the clinical and x-ray results at the one year mark. It’s important to note that most hip sockets do not continue to improve after this point.
Possible Complications When Diagnosed with Acetabular Fractures
Acetabular fractures can lead to several complications. Here are a few of them:
- Post-traumatic arthritis and bone death (osteonecrosis); the risk of developing arthritis later on greatly depends on the quality of the fracture reduction, and the goal should be a reduction within 1 mm
- Infection (about 5% of cases)
- Nerve injury caused by the medical treatment or surgery
- Deep vein thrombosis (DVT) – occurs in about 4% of cases with symptoms, 1% leading to pulmonary embolism
- Problematic surgical devices within the joint
- Abnormal bone growth in non-skeletal tissues (heterotopic ossification), more likely with extended and KL procedures compared to ilioinguinal procedures
Recovery from Acetabular Fractures
Before undergoing the medical procedure, patients who have been in skeletal traction may have alterations in their skin bacteria, as they are unable to clean their perineum properly. To prevent infection, they are typically given preventive antibiotics, such as a first-generation cephalosporin, often combined with additional coverage for certain types of bacteria.
After the procedure, draining tubes may be used for about 48 hours or until there is no more fluid coming out.
Since these patients are at a high risk of developing Deep Vein Thrombosis (DVT), or blood clots in the deep veins of the legs, they are fitted with special compression devices for both legs from the time they’re admitted until they’re discharged. They are also given medication to prevent blood clots until they are able to move around on their own, which is usually after 6 to 12 weeks.
Additional preventive measures are recommended for those who had specific types of surgical approaches, to prevent the formation of bone tissue in the wrong locations (a condition known as heterotopic ossification). These measures may include a single dose of radiation within three days after surgery or taking a specific medication called indomethacin three times a day for 6 weeks, starting within one day after surgery. However, this medicine should not be used in patients with certain bone fractures due to the risk of delayed healing.
Generally, patients are advised to limit their weight-bearing on the affected limb to just the toes or flat of the foot for around 2 to 3 months after surgery. Afterwards, they can start bearing weight as per their comfort levels. Physical therapy usually starts the day after surgery to help with recovery.
Preventing Acetabular Fractures
Preventing hip socket fractures is mostly beyond one’s control, but individuals can take certain precautions when driving vehicles, such as always wearing a seatbelt. Furthermore, older folks should get checked for weak or brittle bones; this includes undergoing DEXA scans, taking Vitamin D or bone-strengthening medicines, and taking steps to prevent trips and falls. These measures can help prevent fractures that may occur due to our bones becoming more fragile as we age.