Acetabular Fractures: Symptoms, Types, Causes and Treatment

Acetabular fractures—breaks in the socket portion of the hip joint—are complex injuries that can have profound impacts on mobility and quality of life. While these fractures are relatively uncommon compared to other skeletal injuries, their incidence is slowly rising, particularly among the elderly population. An understanding of their symptoms, types, causes, and treatment options is essential for both patients and healthcare professionals, given the intricacies of pelvic anatomy and the potential for associated injuries. This article synthesizes current research to provide a comprehensive overview of acetabular fractures, guiding readers through their clinical presentation, classification, etiology, and management strategies.

Symptoms of Acetabular Fractures

The presentation of an acetabular fracture can range from subtle to dramatic, depending on the severity of the injury, patient age, and coexisting trauma. Common symptoms include:

• Severe Hip or Groin Pain: The most immediate and prominent symptom is acute pain localized to the hip or groin region, which worsens with movement or weight-bearing.
• Inability to Bear Weight: Many individuals are unable to stand or walk following the injury.
• Swelling and Bruising: Localized swelling, bruising, and sometimes visible deformity may appear around the hip and pelvic area.
• Restricted Range of Motion: Hip joint mobility is typically severely reduced. Attempts to move the leg often produce pain.
• Shortened and Externally Rotated Leg: In cases where the fracture is associated with hip dislocation, the affected leg may appear shorter and rotated outward.
• Associated Neurological Deficits: Some patients, particularly those with posterior wall fractures, may present with numbness, tingling, or weakness in the leg due to sciatic nerve involvement, though this is relatively uncommon 9.
• Signs of Shock or Internal Injury: High-energy trauma can cause significant internal bleeding, leading to pallor, low blood pressure, rapid pulse, and confusion. Associated injuries to abdominal organs, bladder, or blood vessels can further complicate the clinical picture 8.

Symptoms are often masked in elderly patients or those with multiple injuries, emphasizing the need for a high index of suspicion in trauma settings 5 7 10. The presence of additional injuries may distract from the diagnosis, and missed acetabular fractures can delay appropriate treatment.

Types of Acetabular Fractures

The classification of acetabular fractures is complex, reflecting the intricate anatomy of the pelvis. The most widely used system is the Judet and Letournel classification, which breaks down fractures into ten principal patterns: five elementary (simple) and five associated (complex) types 2 4.

Elementary (Simple) Fracture Types

1. Anterior Wall Fracture: Involves the front rim of the acetabulum.
2. Posterior Wall Fracture: Involves the back rim (most common, especially in high-energy trauma) 2 9.
3. Anterior Column Fracture: Involves the front column of the acetabulum.
4. Posterior Column Fracture: Involves the back column.
5. Transverse Fracture: Passes through the acetabulum horizontally, separating it into upper and lower parts.

Associated (Complex) Fracture Types

These involve combinations of the elementary patterns and include:

• Transverse with Posterior Wall
• T-shaped Fractures
• Both Column Fractures: The entire acetabular articular surface is separated from the pelvic bone—considered the most unique and severe 2.
• Anterior Column or Wall with Posterior Hemitransverse
• Posterior Column with Posterior Wall

Fracture patterns may also involve the quadrilateral plate—a thin bone forming part of the inner acetabular wall. Mapping studies reveal that different fracture types have characteristic fracture line patterns, which can help in surgical planning 4.

Influence of Anatomy and Biomechanics

Recent research shows that the anatomical orientation of the acetabulum (its version) influences fracture patterns. More anteverted acetabula are prone to anterior fracture types, while retroverted acetabula are associated with posterior fractures 3. In elderly patients, fractures more commonly involve the anterior column and quadrilateral plate, often with comminution (multiple bone fragments) and impaction 5.

Classification Challenges

Accurate classification is crucial for guiding treatment but can be challenging due to the pelvis's three-dimensional complexity and the rarity of some variants. Advanced imaging, such as 3D CT, and the use of fracture mapping or flowchart algorithms, can improve diagnostic accuracy and surgical planning 2 4 12.

Causes of Acetabular Fractures

The mechanisms leading to acetabular fractures differ significantly between younger and older populations, as well as between high- and low-energy trauma settings.

High-Energy Trauma

In younger adults, acetabular fractures are most often the consequence of high-energy impacts such as:

• Motor Vehicle Collisions: The leading cause in many series, particularly among young men 7 9.
• Falls from Height: Also a significant contributor, often resulting in more severe or complex fracture patterns 6 7.

In these scenarios, the force transmitted through the femur into the acetabulum during sudden deceleration or impact leads to fracture. The direction of the force vector (axial vs. lateral) influences the fracture pattern and the risk of associated injuries. For example, posterior wall and column fractures are typically caused by an axial load, such as when a flexed knee hits a dashboard, while lateral loads are linked to anterior column injuries 8. Notably, lateral load injuries are more likely to be accompanied by visceral injuries, including damage to the spleen, liver, bladder, or pelvic blood vessels 8.

Low-Energy Trauma and the Elderly

In older adults, especially those with osteoporosis or other comorbidities, acetabular fractures can result from low-energy mechanisms:

• Simple Falls (on the same level): The most frequent cause in the elderly, accounting for nearly half of all acetabular fractures in several population studies 7 10.
• Minor Trauma: Even trivial incidents, such as falling from standing height, can cause significant fractures due to bone fragility 5 10.

Research has found that the incidence of acetabular fractures is increasing in the elderly population, a trend attributed to both a rising proportion of older individuals and greater prevalence of osteoporosis 7 10. Women are disproportionately affected in this group, and fractures tend to involve the anterior column more often, often with complex patterns and comminution 5.

Epidemiological Trends

While overall incidence rates of acetabular fractures have remained relatively stable or only slightly increased in some countries, the age distribution is shifting, with a notable rise among older adults 6 7 10. In contrast, the incidence among younger individuals is steady or declining, possibly due to improved motor vehicle safety and prevention strategies 6 7.

Treatment of Acetabular Fractures

Management of acetabular fractures is highly individualized, taking into account patient age, fracture pattern, bone quality, comorbidities, and the presence of associated injuries. Treatment approaches range from conservative (nonoperative) management to complex surgical interventions.

Nonoperative (Conservative) Management

Nonoperative treatment is generally reserved for:

• Minimally Displaced Fractures: Where the articular surface remains congruent and joint stability is preserved.
• Patients with Significant Comorbidities: When surgical risk outweighs potential benefits, as in frail elderly patients 10.
• Stable Fractures: That do not involve the weight-bearing dome or are not associated with hip dislocation.

Conservative care includes bed rest, limited weight-bearing, pain management, and physical therapy. While this approach avoids surgical risks, it may be associated with poorer functional outcomes if displacement is underestimated.

Surgical Treatment

Surgical intervention is indicated for:

• Displaced Fractures: Where joint incongruity or instability threatens long-term hip function 13.
• Fractures Involving the Weight-Bearing Dome: To restore the architecture and prevent arthritis.
• Associated Injuries: Such as hip dislocation or neurovascular compromise.

Surgical Approaches

• Open Reduction and Internal Fixation (ORIF): The mainstay for most displaced fractures, aiming to restore joint anatomy and stabilize the pelvic ring 13 15. Surgical approaches are tailored to the fracture type; for example, the combined anterior and posterior approach is recommended for complex fractures, providing superior visualization and stabilization 1. The modified Stoppa approach has emerged as an alternative to the traditional ilioinguinal approach, especially for anterior column and quadrilateral plate injuries, with good clinical and radiographic outcomes 14.
• Acute Total Hip Arthroplasty (THA): Especially in the elderly with severe comminution or pre-existing hip disease, primary replacement or combined fixation and arthroplasty may offer better pain relief, function, and lower mortality compared to ORIF alone 10 15.

Advances in Preoperative Planning

Modern imaging technologies, including 3D CT and even 3D printing, allow for highly individualized preoperative planning. Virtual surgical simulation and patient-specific models can aid in understanding complex fracture anatomy, optimizing implant selection and placement, and reducing operative time while improving outcomes 2 12.

Outcomes and Prognosis

• Functional Results: The restoration of the joint surface is crucial for pain-free mobility and prevention of post-traumatic arthritis 13. Satisfactory outcomes are reported in the majority of surgically managed patients, with nearly 70% of older adults achieving functional levels comparable to uninjured peers 11.
• Complications: Risks include infection, nerve injury, avascular necrosis, heterotopic ossification, and post-traumatic arthritis. The rate of secondary total hip arthroplasty (THA) for post-traumatic arthritis is approximately 30% in older patients 11 15.
• Mortality and Quality of Life: In the elderly, acetabular fractures carry a significant one-year mortality risk (14–25%), regardless of treatment modality. Acute THA may be associated with lower mortality and reoperation rates compared to ORIF 10 15.
• Rehabilitation: Early mobilization is encouraged postoperatively to reduce complications, though full weight-bearing may be delayed depending on fracture stability and fixation quality.

Special Considerations in the Elderly

Elderly patients pose unique challenges due to poor bone quality, comorbidities, and increased fragility. Individualized decision-making is essential, balancing the risks and benefits of surgery versus conservative management. The trend toward acute THA, sometimes in combination with internal fixation, reflects an evolving approach aimed at optimizing function and minimizing complications in this vulnerable population 10 15.

Conclusion

Acetabular fractures are challenging injuries that demand precise diagnosis, classification, and individualized management. While high-energy trauma remains the main cause among younger adults, the growing elderly population is experiencing a rise in low-energy, fragility-related acetabular fractures. Advances in imaging and surgical technique, including the use of 3D planning and patient-specific approaches, have improved outcomes, but the risk of complications and need for secondary surgery remain significant—especially in older adults. A multidisciplinary approach, considering the patient’s overall health, fracture pattern, and personal goals, is essential for achieving the best possible results. As the demographic landscape continues to shift, ongoing research and innovation will be vital in addressing the evolving clinical challenges of acetabular fractures.