A 62 yo male with a hx of bilateral hip replacements c/o, "I think I dislocated my hip again."   Patient rolled out of bed and was unable to walk.  An x-ray is shown below.  What's the diagnosis?  Scroll down for answer.

Answer: Anterior prosthetic hip dislocation

• This hip dislocation is managed with similar prompt reduction techniques as would be a native hip dislocation - click here for a review of hip reduction maneuvers.
• Native hip dislocations are usually due to a high energy mechanism, more comonly posteriorly displaced, and are orthopedic emergencies as avascular necrosis may ensue within 6 hours of dislocation.
• Prosthetic hip dislocations, like this one, are much more common (1-10% incidence).  They may be recurrent, and from minor incidents.  They are often easier to reduce. 
• Unlike those with native hip dislocations, patients with prosthetic hip dislocations may often be safely discharged home post-reduction in consultation with the orthopedic specialist.

Reference:  Tintinalli JE, et al.  (2016). Chapter 273 Hip and femur injuries. Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 8th Ed.  New York:  McGraw Hill Education.