Ortho Case of the Week – Shoulder and Hip Dislocation Answers

Case 1: A 45-year-old male BIBEMS after an MVC with left hip pain. His left leg is shortened, adducted, and internally rotated.

1. What is your interpretation of the x-ray above?

Left posterior hip dislocation.

2. What is the most common mechanism for this pathology?

Posterior hip dislocations most commonly occur with significant trauma, with a direct blow to a flexed knee. The most common scenario is in an MVC where the hip is flexed and the knee impacts the dashboard, pushing it back.

Often associated with fractures of the posterior acetabulum or labrum.

3. What nerve is most commonly injured with this pathology? How would you test it?

The sciatic nerve. Occurs in 8-20% of patients.

Test great toe extension and ankle dorsiflexion.

4. Delayed presentation (or identification) of this pathology is most commonly associated with what complication?

Avascular necrosis of the femoral head.

Occurs in 2-10% of hips reduced within 6 hours, and 50% reduced after more than 6 hours. Due to disruption in the femoral and circumflex vessels that supply the femoral head.

5. What is the textbook answer for the time frame within which this pathology must be reduced?

6 hours, though AVN rates are still 2-10% if reduced within 6 hours. Hip dislocations should be reduced as soon as possible.

Case 2: A 75-year-old female presents with right shoulder pain and deformity after a fall.

6. What is your interpretation of the x-ray above?

Right anterior shoulder dislocation.

Humeral head is seen inferior to coracoid process of scapula, with loss of glenohumeral articulation suggestive of anterior dislocation of the shoulder.

7. What nerve is most commonly injured with this type of dislocation? How would you test it?

The axillary nerve is most commonly injured, usually as a transient neuropraxia. Sensation can be tested over the lateral shoulder in the “military patch” distribution. Most commonly occurs with inferior shoulder dislocations, but can happen with any type.

8. If her shoulder had been dislocated for >3 weeks, how would your management change? What could happen if you tried to reduce it?

These patients require an orthopedics consult due to the risk of axillary artery rupture. These patients will likely require operative intervention.