A review of posterior hip dislocations.

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Posterior hip dislocations account for roughly 85% of hip dislocations, and the most common cause is a high-energy dashboard injury from a MVA.

The use of seatbelts significantly decreases the risk of dashboard injuries.

The Thompson and Epstein Classification system is used for posterior hip dislocations:

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Patients with posterior hip dislocation will present with severe hip pain and the hip flexed, adducted, and IR.

Due to the high energy MOI, a full trauma survey and neurovascular exam are essential in initial management.

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It is important to assess the sciatic nerve for injury. The injury most commonly affects the peroneal distribution, with the tibial distribution is typically unaffected.

Ipsilateral knee injuries such as patella fx, femur fx, PCL tear, and/or meniscal tears may occur.

When reviewing radiographs r/o concomitant acetabulum, femoral head, and neck fractures.

Shenton's line will be disrupted in dislocations and the femoral head will appear smaller in posterior dislocations as opposed to anterior dislocations when it will appear larger.

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Urgent closed reduction should be performed to minimize the risk of femoral head AVN, supplied by the Medial Femoral Circumflex a. Prognosis is worsened if the reduction is delayed > 12 hrs.

Do not attempt reduction if there is a femoral neck, it should be stabilized first

Four methods for reduction are the Allis Method, The Stimson Gravity technique, Bigelow Maneuver, and the Reverse Bigelow Maneuver.

The two most commonly used are the Stimson Gravity and Allis Technique:

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Following closed reduction, hip stability should be assessed.

Once this is complete all patients with traumatic hip dislocation should undergo a CT scan of the hip to rule out femoral head fx, acetabular fx, or loose bodies.

Complications include:
Femoral head AVN: 5-40%, repeated reduction attempts may increase risk and AVN may become clinically apparent several years after injury.

Post Traumatic Arthritis: up to 20%, more common in complex dislocations

Recurrent dislocation: < 2%

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Ortho Reviews - Posterior Hip Dislocations