Review Question - QID 219178

The patient has a complex posterior wall acetabulum fracture-dislocation, with multiple risk factors for early onset post-traumatic arthritis, indicating the patient for open reduction and internal fixation (ORIF) of the posterior wall fragment with coinciding acute total hip arthroplasty (THA) (Answer choice 3).

In this patient population, there is a heightened risk of early onset post-traumatic osteoarthritis arising from various factors, such as advanced age, involvement of the posterior wall, dislocation, displacement exceeding 1 cm, comminution, femoral head damage, and marginal impaction. Additionally, the patient's physiologic youth makes fixation and simultaneous total hip arthroplasty the most favorable approach as this exposes the patient to a single surgical event, one hospital admission with equivalent rates of postoperative complications compared to a staged procedure. Notably, this strategy also yields superior functional outcomes compared to alternatives like isolated ORIF with delayed THA.

Nicol et al. compared outcomes of THA for elderly acetabular fractures, specifically evaluating delayed THA after initial ORIF versus acute ORIF and THA. The ORIF and acute THA group showed similar operative time, length of stay, fewer complications, and superior functional outcomes on the Oxford Hip Score measure compared to the ORIF and delayed THA group. The findings suggest that, for elderly patients at risk of failure requiring delayed THA, considering ORIF and acute THA may be advantageous.

Tannast et al. completed a 26-year analysis of 816 acetabular fractures treated with ORIF, which revealed a cumulative 20-year survivorship of 79%. Significant predictors for total hip arthroplasty after acetabular ORIF included: non-anatomical fracture reduction, age over 40, postoperative incongruence of the acetabular roof, posterior acetabular wall involvement, acetabular impaction, femoral head cartilage lesion, initial displacement of the articular surface over 20 mm, and use of the extended iliofemoral approach.

Firoozabadi and colleagues analyzed data from 156 patients over 65 years old with acetabular fractures. It was found that falls and motor vehicle accidents were the primary mechanisms of injury. In their cohort, surgical intervention demonstrated lower mortality rates, with the most common fracture patterns being associated both-column (ABC) or anterior column/posterior hemitransverse (AC/PHT). The findings highlight the rarity of geriatric acetabular fractures, emphasize the importance of surgical intervention for improved outcomes, and suggest routine fixation techniques for managing these challenging injuries.

Figure A is an AP radiograph of a left posterior hip dislocation with associated posterior wall acetabulum fracture. Figure B is a coronal CT scan demonstrating marginal impaction. Figure C is a 3D CT reconstruction with femoral head subtraction demonstrating the comminuted nature of the posterior wall fragment.

Incorrect Answers:
Answer 1: This patient has a complex posterior wall acetabulum fracture-dislocation, without posterior column involvement. Furthermore, the presence of a concomitant femoral head injury would be an indication to pursue acute THA.
Answer 2: The roof arc angle is an angle between a vertical line through the femoral head and a line through the acetabulum fracture, however, this angle does not apply to posterior wall patterns as there is no intact portion of the acetabulum to measure. Also, changes in the roof arc angle are not associated with early-onset post-traumatic arthritis in the elderly population.
Answer 4: Marginal impaction correlates with early post-traumatic arthritis, potentially eliminating the need for THA when absent. Also, over 20% posterior wall involvement could warrant ORIF but does not necessitate acute THA.
Answer 5: The patient has fractured the posterior wall of the acetabulum, not the anterior wall.