Acetabulum Fractures: Diagnosis, Treatment, and Prognosis

TRAUMA 2023, Sep, 14 | 12:00 am

Acetabulum Fractures: Diagnosis, Treatment, and Prognosis

Acetabulum Fractures

Acetabulum fractures are pelvis fractures that involve the articular surface of the hip joint and may involve one or two columns, one or two walls, or the roof within the pelvis. Here's what you need to know about their diagnosis, treatment, and prognosis:

Summary

Diagnosis can be made radiographically with dedicated pelvis radiographs (including Judet views) but frequently require CT pelvis for surgical planning. Treatment can be nonoperative for non-displaced fractures but displaced injuries require anatomic open reduction and internal fixation to minimize development of post-traumatic osteoarthritis.

Epidemiology

Incidence: ~ 4 per 100,000 per year

Demographics: Fractures occur in a bimodal distribution, with high energy trauma in younger patients (e.g., motor vehicle accidents) and low energy trauma in elderly patients (e.g., fall from standing height).

Etiology

Pathoanatomy: The fracture pattern is predominately determined by the force vector, position of the femoral head at the time of injury, and bone quality (e.g., age).

Associated conditions: Orthopaedic manifestations include lower extremity injury (36%), nerve palsy (13%), spine injury (4%). Systemic injuries include head injury (19%), chest injury (18%), abdominal injury (8%), and genitourinary injury (6%).

Figure 1: Acetabulum Fracture (Source: Hutaif Orthopedic Center)

Anatomy

Osteology	Acetabular inclination & anteversion: Mean lateral inclination of 40 to 48 degrees Anteversion of 18 to 21 degrees Column theory: Acetabulum is supported by two columns of bone Columns form an "inverted Y" and are connected to the sacrum through the sciatic buttress: Posterior column Comprised of quadrilateral surface, posterior wall and dome, ischial tuberosity, greater/lesser sciatic notches Anterior column Comprised of anterior ilium (gluteus medius tubercle), anterior wall and dome, iliopectineal eminence, lateral superior pubic ramus
Vascular	Corona mortis: An anastomosis of external iliac (epigastric) and internal iliac (obturator) vessels that is at risk with lateral dissection over superior pubic ramus.

Osteology

Acetabular inclination & anteversion:

Mean lateral inclination of 40 to 48 degrees
Anteversion of 18 to 21 degrees

Column theory:

Acetabulum is supported by two columns of bone
Columns form an "inverted Y" and are connected to the sacrum through the sciatic buttress:

Posterior column

Comprised of quadrilateral surface, posterior wall and dome, ischial tuberosity, greater/lesser sciatic notches

Anterior column

Comprised of anterior ilium (gluteus medius tubercle), anterior wall and dome, iliopectineal eminence, lateral superior pubic ramus

Vascular

Corona mortis: An anastomosis of external iliac (epigastric) and internal iliac (obturator) vessels that is at risk with lateral dissection over superior pubic ramus.

Letournel Classification

The Judet and Letournel classification system is the most commonly referenced system and classifies fractures as 5 elementary and 5 associated fracture patterns. The most common fracture patterns are:

Youth

Posterior wall
Transverse fracture "family"
- Transverse
- T-type
- Transverse + posterior wall

Elderly

Anterior column (e.g., quadrilateral plate fractures)
Anterior column, posterior hemitransverse
Associated both column fractures

(View Classification Images)

Imaging

Radiographs: The recommended views include AP, Judet (including obturator and iliac oblique views), and optional views such as inlet/outlet if concerned for pelvic ring involvement and examination under anesthesia (EUA). Findings may include radiographic landmarks of the acetabulum, such as iliopectineal line (anterior column), ilioischial line (posterior column), anterior wall, posterior wall, teardrop, and weight bearing roof. Roof arc angle and gull sign may also be noted.

CT Scan: Indications include fracture pattern orientation, identifying fragment size and orientation, identifying marginal impaction, identifying loose bodies (e.g., post-reduction), and looking for articular gap or step-off. Roof-arc measurements can also be taken.

(View CT Classification Images)

Treatment

Nonoperative: Protected weight bearing for 6-8 weeks with activity as tolerated is indicated for patients with minimally displaced fracture (< 2 mm), < 20% posterior wall fractures, femoral head congruency with weight bearing roof (out of traction), and displaced fracture with roof arcs > 45° in AP and Judet views or >10 mm on axial CT cuts.

Operative treatment: Open reduction and internal fixation (ORIF) is indicated for patients with displacement of roof, unstable fracture pattern, marginal impaction, intra-articular loose bodies, and irreducible fracture-dislocation. Various approaches to ORIF are available with distinct techniques and outcomes.

Techniques

The following techniques are available:

Percutaneous fixation with column screws
ORIF with approaches that depend on the fracture pattern
Total hip arthroplasty (THA) is indicated for elderly patients with significant osteopenia and/or significant comminution, pre-existing arthritis, or post-traumatic arthritis in all ages

Complications

Complications may include post-traumatic DJD, heterotopic ossification, osteonecrosis, DVT and PE, infection, bleeding, neurovascular injury, intraarticular hardware placement, and abductor muscle weakness.

Prognosis

Poor outcomes are associated with multi-system trauma, increasing age, poor articular congruency, associated femoral head articular injury, and post-traumatic arthritis.