this injury is commonly associated with multiple lesions such as acetabular fractures , nerve palsy and femoral head fractures , due to its high energy trauma mechanism .
bilateral hip dislocation is an extremely rare finding , with very few cases reported in literature [ 2 , 3 ] .
most are related to acetabular or proximal femoral fractures , consisting of complex lesions , and are rarely are pure ligamentous injuries . in the diagnosis of a dislocated hip , prompt reduction must follow to prevent future complications like avascular necrosis ( avn ) [ 1 , 3 ] .
the following case report consists in the presentation of a traumatic bilateral posterior hip dislocation without associated injuries .
the patient is a 23-year - old female , with no comorbidities , who sustained bilateral hip pain after an automobile accident . at the time of the accident patient was driving her vehicle and
the accident happened while the patient was driving and had her hips and knees in a flexed position , thus transmitting loads to the posterior aspect of the hips and forcing dislocation .
only mild head trauma and severe hip pain was reported by paramedics at the time she was primarily attended .
she was referred to the emergency room unable to move her legs and had slight hip flexion with internal rotation .
physical examination revealed 20 hip flexion with 30 internal rotation , sensitivity and muscular strength were intact , pain was intensified when passive or active limb motion was attempted .
antero - posterior radiographs were taken , diagnosing bilateral posterior hip dislocation with no evidence of associated fractures ( fig .
1 ) . computed tomography was realized to evaluate fractures and articular fragments and none were found ( fig .
an hour after initial evaluation , the patient was admitted to the operating room , under general anesthesia , and closed reduction of both hips was performed without incidents .
stability and range of motion was assessed , with normal findings ; control x - rays showed concentric hip reduction of both femoral heads ( fig .
physical therapy was initiated the first week with quadriceps and gluteal muscles isometric exercises and passive hip movements . at second week
after 6 weeks follow - up the patient achieved a complete hip range of motion and walked without assistance . 

figure1 : patient with hip flexion and internal rotation and x - ray with traumatic bilateral posterior hip dislocation.figure 2:ct - scan show bilateral posterior hip dislocation without evidence of fracture or articular fragments.figure 3:after closed reduction - hip abduction and external rotation . 1 : patient with hip flexion and internal rotation and x - ray with traumatic bilateral posterior hip dislocation .
ct - scan show bilateral posterior hip dislocation without evidence of fracture or articular fragments . after closed reduction - hip abduction and external rotation .
the classification of traumatic hip dislocation is based of dislocation and the degree of joint disruption including any associated joint fracture .
three commonly used classifications systems are : the epstein classification of anterior hip dislocation , pipkin sub - classification an the thompson - epstein classification of posterior dislocation   as in this case report .
simple injuries are dislocations without associated fractures , whereas complex injuries include either acetabular or proximal femoral fractures .
posterior dislocations represent the majority of these injuries , occurring due to an axial load of the femur , with the hip flexed and adducted .
usually , the axial load is transmitted through a flexed knee , as in dashboard injuries [ 3 , 5 , 6 ] .
anterior dislocations , in contrast , occur with the hip in abduction and external rotation , and the position of the femoral head can be either inferior or superior to the acetabulum .
motor vehicle accidents are the leading cause of hip dislocations , followed by falls from significant heights ; sports related injuries have also been reported in literature [ 6 , 7 ] .
bilateral simultaneous hip dislocations are an extremely rare injury , a reported 1.25% of all hip dislocations [ 3 , 68 ]
. these injuries are rarely present as isolated dislocations , and often associate fractures , usually of the acetabulum .
these acetabular fractures frequently relate to the type of dislocation , posterior dislocation with posterior wall and column fractures and anterior dislocation with anterior wall fractures [ 1 , 5 , 7 ] .
a patient with a dislocated hip usually presents acute pain and evident deformity , with an inability to tolerate active or passive range of motion . of all
, 95% of these patients have associated injuries , and for this reason an adequate trauma emergency evaluation must be realized in the moment of arrival , following the atls sequence of patient evaluation .
a ct scan is also important , presence of intra - articular fragments needs to be discarded ; this imaging also functions as means of postoperative follow up [ 3 , 7 , 8 ]
. soft tissue injuries such as avulsions of the labrum may be assessed by magnetic resonance imaging , but are not requested routinely .
heterotopic calcifications , avascular necrosis and osteoarthritis can also be evaluated with magnetic resonance imaging as part of the patient follow up .
treatment of hip dislocations can be either operative or nonoperative , but emergent reduction of the joint is of upmost importance .
delay in reduction of dislocated hip results in avascular necrosis in around 26% of patients .
early mobilization results in a prompt return to weight bearing , but the outcome and relationship with complications such as avascular necrosis is largely debated .
closed reduction of a posteriorly dislocated hip implies general anesthesia and an adequate positioning of the patient .
several techniques have been described , all of which include traction and counter - traction as part of the maneuver .
post reduction imaging studies must be performed to assess the quality of the reduction and presence of associated injuries that may have been neglected initially .
open reduction is performed in the case of an irreducible dislocation , a delayed presentation or articular fragments that make a concentric reduction impossible .
 abstractbilateral traumatic hip dislocations are extremely rare . 
 most of these are related to acetabular or proximal femoral fractures , consisting of complex lesions , and are rarely pure ligamentous injuries . 
 posterior dislocation is the most frequent . 
 some dislocations are accompanied by sciatic nerve palsy . 
 the present case is a posterior bilateral hip dislocation with no other associated lesions , there are very few reports published with this clinical setting . 
 the patient had good functional outcome . 