Acetabulum Fracture

Original Editor - Lise Delagrange

Top Contributors - Scott Buxton, 127.0.0.1, Lise Delagrange, Lauren Lopez, Lucinda hampton, Angeliki Chorti, Tony Lowe, Kim Jackson, Candace Goh, Admin, Didzis Rozenbergs, Sweta Christian and WikiSysop  

Introduction

The acetabulum is the large cup-shaped cavity on the anterolateral aspect of the pelvis that articulates with the head of the femur to form the hip joint. Acetabular fractures (a type of pelvic fracture), possibly involving the ilium, ischium or pubis depending on fracture configuration.

Epidemiology

Acetabular fractures are uncommon. The reported incidence is approximately 3 per 100,000 per year.

Pathology

Mechanism

1. High-energy trauma: axial loading of the femur: fall from height; Motor vehicle collision; crush injury
2. Low-energy trauma with abnormal bone: insufficiency fracture eg Osteoporosis makes the bone vulnerable and can cause an acetabulum fracture from a simple low fall .

Diagnostic Procedures

There are various numbers of fracture patterns in the acetabulum. For the classification of these fractures, the Judet-Letournel classification is most accepted system. The five most common fractures, representative for 90% of all, are:

1. 'Both' column: This is a fracture that involves the anterior and posterior column and extends through the obturator ring. The characteristic for this fracture is the spur sign. It is a sign that represents the displacement of the fracture involving sciatic buttress. When this is present, the acetabulum can no longer carry the weight of the upper body.
2. Transverse: This fracture involves both anterior and posterior column. This means that the iliopectineal and ilioischial lines of the pelvis are discontinue.
3. T-shaped: Similar to the transverse fractures, the difference is that the T-shaped also extends inferiorly into the obturator ring. What differentiates it from the both column fracture is that the fracture doesn’t involve the extension to the iliac wing. 
4. 'Transverse' with posterior wall: This is a transverse fracture only there is also a comminution of the posterior wall.
5. 'Isolated 'posterior 'wall: One of the most common acetabulum fractures with a preponderance of 27 %. The posterior wall in this fracture is comminuted. The iliopectineal line is not disrupted but the ilioischial line may be . 
    

Examination

CT has revolutionised the diagnosis, enabling precise delineation of the fracture configuration and assessment of any articular surface disruption.
The radiograph gives a clear view of all the essential fundamental landmarks of the acetabulum.
On a CT-scan you can see  full 3D- reconstruction of the acetabulum, which facilitates the visualization of the fracture, the degree  of the fracture and the associated fractures.
 

Medical Management 

Treatment depends on several factors including both patient factors and fracture characteristics. Treatment, whether operative or non-operative will usually be followed by a period of non-weight bearing on the affected side (or both). Close radiographic follow-up is required.

If the displacement of the fragment is greater than 3mm, operation is primarily  suggested. Non-operative management may be indicated in the setting of minimally displaced fracture. It is more common in developing countries.
These fractures often require an open reduction internal fixation (ORIF) to restore joint congruency and stabilization. For the operation they use screws and plates to fix the bone to prevent further displacementWith elderly patients, ORIF may not always be the best option because of possible osteoporosis. ORIF can be the solution to the fracture if the femoral head is still weight bearing and when the patient factors are no immediate cause to any complication. Patient factors include degree of underlying osteoporosis, comorbid medical conditions, preexisting degenerative joint disease (DJD), premorbid activity level, and baseline mental function.
In general total hip replacement will provide the best functional outcome in elderly patients with severe acetabulum fracture and osteoporosis. 

Physical Management

Usually this nonoperative treatment is recommended for patients with no displacements or minimal displacement like low anterior column or low transverse fractures, so the superior part of the acetabulum must be intact.

Early mobilization is necessary because prolonged recumbency can be life- threatening.  Conservative  treatment includes pain control, functional physical therapy and radiographic follow-up. Physical therapy include gait training, stabilization exercises and mobility training.

Patients who underwent an operation have to start with passive ROM exercises followed by active non weight bearing such as a series of flexion/extension . Partial weight-bearing with stepwise progression usually starts 6 weeks postoperatively and full weight bearing is eventually allowed at 10 weeks.