Posterior Prosthetic Hip Dislocations

HPI:
55 y/o male with history of etoh abuse and bilateral THA presents with left hip pain and inability to walk. He has been drinking etoh and playing with his grandchildren when he noticed his left hip dislocated. This occurs monthly.

EXAM:
Left leg is slightly shorter than right. Leg and hip in flexion, adduction, and internal rotation. Able to palpate the femoral head. No deficits of foot function noted.

IMAGES:
Obtain AP and Lateral Hip

MANAGEMENT:
#Non-operative
- First line when no associated fractures are present
- Frequently requires sedation but not paralyzation (unlike traumatic which requires both)
- Flex the hip and knee to 90 degrees, place axial traction, internally rotate the hip with a second person placing counter traction on the hip
- Second person can help guide the femoral head into proper positioning
- Place in knee immobilizer post reduction to prevent recurrence

#Operative
- Indications include inability to reduce non-operatively, associated fractures, multiple dislocations
- Revision of THA can occur as an outpatient and does not require admission

DISCUSSION:
- Posterior dislocation occurs in 75-90% of cases
- Risk factors: prior hips surgery, etoh abuse, age >70, malpositioning of components, etoh abuse, neuromuscular disease
- Mechanism: hip flexion, adduction with internal rotation. (ie: shoe tying, sitting on toilet)
- Easier to reduce than traumatic dislocations, should not require paralytics
- Fracture of the femur is a complication of the procedure, especially with predisposing diseases (etoh abuse, chronic steroids)
- AT CMC, protocol is to reduce in PACU under sedation
- Can d/c home following reduction with ortho follow up
- Anterior dislocations can be reduced with axial traction and internal rotation without flexion of the hip.

KEY POINTS:
- 90% posterior dislocations (hip in flexion, adduction, internal rotation)
- Hip x-rays to assess for dislocation type and for fractures
- Frequently only requires sedation without paralytics
- Reduction by hip/knee flexion to 90 degrees, axial traction and internal rotation
- Frequently requires a lot of force to reduce
- Place in knee immobilizer post reduction to prevent recurrence
- Don’t break the femur

by Dr. Mohamed El-Kara


References:
http://medapparatus.com/Ortho/Images/JointArthroplasty/DislocatedLeftHipArthroplasty.jpg
http://www.orthobullets.com/recon/5012/tha-dislocation