Review Question - QID 219131

Malreduction of acetabular fractures after open reduction and internal fixation (ORIF) represents the highest risk for requiring revision to total hip arthroplasty (THA).

Acetabular fractures can occur in younger patients after high-energy trauma or in older patients after ground-level falls. Classification of fracture patterns is important in understanding approach and fixation strategies. ORIF represents the most common strategy for stabilizing acetabular fractures due to the ability to re-establish the acetabular anatomy. However, around 20% of fractures treated with ORIF go on to require transition to THA, most commonly due to the development of post-traumatic arthritis. The most important predictive factor for ultimately requiring THA is the malreduction of the acetabulum articular surface at the time of fixation. This relationship is linear and as the degree of malreduction increases, so does the risk for developing post-traumatic arthritis.

Firoozabadi et al. sought to identify risk factors for early conversion to THA after fixation of acetabular fractures involving the posterior wall. They noted that rates of conversion to THA were 5%, 14%, and 17% at 2, 5, and 9 years, respectively. They concluded that acetabular fractures with posterior wall involvement had a much higher rate of conversion to THA if the reduction was not anatomic.

Tannast et al. looked at 816 acetabular fractures treated with ORIF over a 26-year period in order to evaluate survivorship. They noted that at 20 years the cumulative survivorship was 79%. Risk factors for conversion to THA included non-anatomic fracture reduction, age >40, anterior hip dislocation, postoperative roof incongruence, posterior wall involvement, articular impaction, femoral head cartilage lesions, articular surface displacement >20 mm, and utilization of an extended iliofemoral approach.

Ding et al. attempted to identify risk factors for early reoperation after acetabular ORIF in 791 patients. There were 45 conversions to THA with risk factors including hip dislocation, articular comminution, and concomitant femoral head/neck injury. With regards to the 56 infections in the cohort, risk factors included prolonged ICU stays, prolonged OR times, patients who underwent embolization, or those who experienced a delay in time to fixation.

Incorrect Answers:
Answer 1: While ranges vary, the need for THA after acetabular ORIF is estimated at around 20% at 20 years.
Answer 2: Risk for infection increases as operative time increases.
Answer 4: A delay in operative fixation of acetabular fractures has demonstrated an increased risk for fracture malreduction.
Answer 5: Acetabular fractures involving the posterior wall have been shown to have a higher risk of developing arthritis and needing eventual THA.