A four year old female is brought to the emergency 
department with a complaint of right hip and knee pain. 
About two hours prior to presentation, the child had 
been running when she slipped and refused to bear 
weight or move her right lower extremity.  There is no 
other history of significant medical or surgical problems.
     Exam:  VS:  T 36.7, P120, RR 24, BP 120/77.  She 
is awake and alert in no acute distress.  Her right lower 
extremity is held in flexion at the hip and knee, 
adducted and internally rotated.  A bony prominence at 
her right gluteal region is appreciated.  She resists 
attempts at passive range of motion about the hip 
because of  pain.  Pulses are full.  Motor and sensory 
functions are all intact.  The rest of her physical 
examination is normal.  Radiographs of the pelvis and 
hips are obtained.

View Pelvis and Hip Radiographs.
AP view.


Oblique view.


     The AP view shows a dislocation of the right hip.  
The oblique view is difficult to interpret.  Clinically, this 
is a posterior dislocation.  There is no evidence of 
fracture. The patient was sedated in the emergency 
department.  Closed reduction of the right hip was done 
by applying traction in line with the deformity and gently 
flexing the hip to 90 degrees.  Concentric reduction was 
obtained.  Repeat radiographs showed complete 
reduction with no evidence of fracture or epiphyseal 
injury.

View Post-Reduction Pelvis and Hips.
AP view.


Frog view.


     The child was hospitalized and underwent 48 hours 
of skin traction. Upon discharge, she had continued full 
range of motion, no pain and no evidence of 
redislocation.  She was followed-up by the orthopedic 
service for several months.

Teaching Points: 
     1. Traumatic hip dislocation (THD) is an uncommon 
injury in children and adolescents.  Falls are the single 
most common cause followed by high velocity injuries 
such as motor vehicle accidents and sports-related 
incidents.  Boys are more frequently affected than girls.  
It may also be seen in relatively minor trauma in young 
children less than 5 years of age due perhaps to joint 
laxity and a shallow acetabular fossa.
     2. Posterior dislocations are more common than 
anterior dislocations.  These injuries often occur after a 
blow to the knee with the hip and knee in flexion, as in 
a motor vehicle crash with an unrestrained child striking 
one knee against the dashboard.  The leg would be 
adducted, flexed and internally rotated at the hip, as in 
this case.  There is a relative shortening of the 
extremity and protrusion of the greater trochanter into 
the gluteal region.  Anterior dislocations, on the other 
hand, are usually caused by an excessive external 
rotation or a direct blow to the greater trochanter with 
the hip externally rotated.  The leg would typically be 
held in abduction, extension and external rotation.
     3. The occurrence of an obvious traumatic episode 
followed by limb dysfunction and local evidence of injury 
of the affected body part narrows the differential 
considerably.  A plain radiograph may confirm a 
fracture, avulsion, dislocation or soft-tissue injury.  In 
cases of THD, other views of the hip joint (e.g. oblique 
and lateral views) may be difficult to obtain because of 
the limited range of motion in some patients.  Additional 
radiographs of the ipsilateral extremity may be indicated 
to rule out other fractures or injuries.  Approximately 
25% of hip dislocations are associated with knee 
injuries. 
     4. Early recognition is essential in the management 
of THD.  Immediate closed reduction (within 6 hours 
after the injury) under general anesthesia or 
intravenous sedation has been shown to have a better 
prognosis.  A hip dislocation is reduced by flexing the 
hip and knee to 90 degrees and applying axial traction 
of the thigh.  Repeat pelvic radiographs which show a 
widened medial joint space indicate an incomplete 
reduction.  Late diagnosis and failure to achieve a 
concentric reduction invariably requires an open 
reduction.  After a successful reduction, immobilization 
either with traction or spica cast, may be done to 
maintain stability.  There is no consensus in the 
orthopedic literature about the type of post-reduction 
care or the duration of non-weight bearing significantly 
affecting the prognosis of THD.
     5. Computed tomography (CT) has been used after 
reduction attempts to identify fractures or intraarticular 
loose bodies not apparent on standard radiographs.  
Magnetic resonance imaging (MRI) has also been 
found to improve the diagnostic accuracy of hip 
dislocation.  Studies to compare the two modalities 
have yet to be done. 
     6. The major complications of THD are frequent and 
include avascular necrosis, recurrent dislocation, sciatic 
nerve injury or traction injuries and traumatic arthritis.  
The severity of the trauma and the period until 
reduction are considered to be important prognostic 
factors.

References
     1. Attia MW, Gould JH.  Traumatic hip dislocation in 
a young child:  A case report and discussion. Pediatric 
Emergency Care.  1995;11(5):291-293.
     2. Bachman D, Santora S.  Orthopedic Trauma.  In:  
Fleisher GR, Ludwig S (eds).  Textbook of Pediatric 
Emergency Medicine, 3rd edition.  Baltimore, MD, 
Williams & Wilkins, 1993, pp. 1267-1268.
     3.  Huo MH, Root L, Buly RL, Mauri TM.  Traumatic 
Fracture-Dislocation of the Hip in a 2-Year-Old Child. 
Orthopedics. 1992:15:1430-1433.
     4.  Moseley CF.  Fractures and Dislocations of the 
Hip.  Instructional Course Lectures. 1992;41:397-401.
     5.  Poggi JJ, Callaghan JJ, Spritzer CE, et al. 
Changes on Magnetic Resonance Images After 
Traumatic Hip Dislocation.  Clinical Orthopaedics and 
Related Research.  1995;319:249-259.
     6.  Simon RR, Koenigsknecht SJ.  The Hip, Pelvis 
and Thighs.  In:  Emergency Orthopedics, 3rd edition. 
Norwalk, CT, Appleton & Lange, 1995, pp. 430-435.