From the Research
To distinguish between posterior and anterior hip dislocations, assess the position of the affected limb and conduct appropriate imaging studies, as the most recent and highest quality study 1 emphasizes the importance of prompt diagnosis and treatment. When evaluating a patient with a suspected hip dislocation, it is crucial to consider the mechanism of injury, physical examination findings, and imaging results. Posterior dislocations, which account for approximately 90% of cases, typically result from high-energy trauma with force applied to a flexed knee while the hip is flexed, such as dashboard injuries in car accidents. In contrast, anterior dislocations occur when the leg is abducted, externally rotated, and extended during trauma.
Some key differences between posterior and anterior hip dislocations include:
- Position of the affected limb: posterior dislocations present with the leg shortened, internally rotated, and adducted, while anterior dislocations present with the leg externally rotated, abducted, and sometimes flexed
- Radiographic findings: in posterior dislocations, the femoral head appears posterior and superior to the acetabulum, while in anterior dislocations, it appears anterior and often inferior
- Associated injuries: posterior dislocations may have acetabular fractures or sciatic nerve injuries, while anterior dislocations can have femoral vessel or nerve damage
Prompt reduction is essential to prevent avascular necrosis of the femoral head, which becomes more likely after 6-12 hours of dislocation, as highlighted in the study 2. The study 3 also notes that sedation with propofol is significantly more effective than combination fentanyl/midazolam for closed reduction of native hip dislocations, which can help guide treatment decisions. Additionally, the study 4 emphasizes the importance of evaluating for intra-articular hip pathology, even if plain radiographs and CT scans show a concentric reduction, as this can contribute to long-term degenerative changes.
Overall, a thorough evaluation and prompt treatment are critical in managing hip dislocations, and the most recent and highest quality study 1 provides valuable guidance on the diagnosis and treatment of anterior hip dislocations.