INTRODUCTION
In general the hip joint is quite stable due to its bony structure and attached ligaments and significant force is required to cause hip dislocation. However, hip dislocations after trauma can be frequently encountered in the emergency department

Due to traumatic etiology, hip dislocations are often associated with major injuries such as fractures in over half these patients. The majority of all hip dislocations are due to automobile accidents

Posterior hip dislocations are the most common type, with anterior type occurring only about 10% of cases

These cases are considered as orthopedic emergencies and should be treated as such and majority will resolve by performing a closed reduction in the emergency department

ANTERIOR DISLOCATION –ETIOLOGY
• Occurs when hip is forcibly in abduction and external rotation
• Usually associated with femoral head impaction or chondral injury
• Occur following a fall or road traffic accident

EPIDEMIOLOGY OF HIP DISLOCATIONS
• Most commonly encountered in young, adult males
• Typically occur following automobile accidents.
• Recent study found the average age of these patients to be about 34 years with over 90% male. Other associated injuries common mostly fractures involving the hip
• Over 90% usually treated with emergency closed reduction, typically within 12 hours
• Delayed treatment associated with an increased risk of complications
• Anterior dislocations of the hip in children is rare

TYPES OF ANTERIOR DISLOCATION
• There are three types of anterior hip dislocations
• Obturator, is an inferior dislocation associated with simultaneous abduction; hip flexion; and external rotation
• Iliac and pubic dislocations are superior dislocations caused by simultaneous abduction, hip extension, and external rotation

EPSTEIN CLASSIFICATION OF ANTERIOR HIP DISLOCATION
Type 1: Superior dislocations
• 1A – Not accompanied by fracture
• 1B – Accompanied by fracture or impaction of the femoral head
• 1C – Associated fracture of the acetabulum

Type 2: Inferior dislocations
• 2A – Not accompanied by fracture
• 2B – Accompanied by fracture or impaction of the femoral head
• 2C – Associated fracture of the acetabulum

CLINICAL FEATURES OF ANTERIOR HIP DISLOCATION
• Severe pain in hip and inability to weight bear
• Superior anterior dislocations typically present with hip extended and externally rotated
• Inferior anterior dislocations usually present with the hip abducted and externally rotated
• Other associated injuries and hip fracture may be present
• Sensory loss over the anteromedial aspect of the thigh and medial side of the leg and foot should raise suspicion of anterior hip dislocation (due to injury to femoral nerve)
• Although sciatic nerve injuries are more common in posterior dislocations, they should be ruled out in any suspected hip dislocation or fracture
• Additionally full trauma evaluation for other injuries is recommended

DIAGNOSTIC IMAGING FOR HIP DISLOCATION
X-RAYS

• Hip dislocations usually are evident on standard AP (anteroposterior) images of the pelvis.
• However, a cross-table lateral image of the affected joint is done to differentiate between anterior and posterior dislocations as well as rule out femoral neck fracture prior to attempting closed reduction
• Judet views (45 degree internal and external oblique views) may help to detect bone fragments and occult acetabular and femoral head and neck fractures
• Findings include loss of congruence of femoral head with the acetabulum and disruption of Shenton’s line

• Femoral head on the side of dislocation appears larger than the opposite femoral head
• Femoral head on affected side is medial or inferior to acetabulum

CT SCAN
• Helps in finding the direction of dislocation, presence of loose bodies, and associated fractures
• Post reduction CT is advisable to look for occult femoral head and acetabular fractures and presence of loose bodies that may preclude proper joint articulation
• CT may be useful in preoperative planning of open reduction if closed reduction attempts are unsuccessful

MRI SCAN
Routine use is not advised
May be indicated if issues persist after initial treatment in order to evaluate labrum, cartilage and femoral head vascularity

ADDITIONAL TESTS
If moderate blood loss is suspected, hemoglobin and hematocrit should be requested as well as blood group and type plus crossmatching

TREATMENT OF ANTERIOR HIP DISLOCATION
Prompt reduction of any hip dislocation is critical. Immediate attempts should be made to perform a closed reduction within 6 hours as long-term outcome may be unfavorable by greater delays. Contraindications to open reduction include displaced or non-displaced femoral neck fracture on the side of dislocation

Pain relief is important as many of these patients are in considerable pain

CLOSED REDUCTION OF ANTERIOR HIP DISLOCATION
• Closed reduction must be done with the patient supine and traction applied in line with deformity whatever be the direction of dislocation
• Adequate sedation and muscle relaxation is essential before attempting closed reduction
• The various techniques described for closed reduction of anterior hip dislocation include Allis maneuver, Reverse Bigelow maneuver and Stimson maneuver
• Following the procedure, patients must be positioned with legs immobilized in slight abduction with a pillow or device between the knees. Ice packs should be applied, and painkillers must be given
• X-rays must be obtained post reduction to rule out occult fractures and loose fragments and patient may need to be admitted for continued care

OPEN REDUCTION
Various surgical approaches for reducing an anterior hip joint are possible; however, firstly irrigation of the joint is important to remove possible loose bodies and rule out soft tissue abnormalities that would prevent proper joint articulation. Postoperatively the hips should be held in traction for 6 to 8 weeks or until the pain has fully settled down

POTENTIAL COMPLICATIONS OF ANTERIOR DISLOCATION
• Concurrent femoral head trauma may be associated with less favorable functional outcomes
• Osteonecrosis of femoral head
• Thromboembolism due to limb immobilization
• Recurrent dislocation (2% incidence)
• Neurovascular injury (rare)

KEY POINTS
• Anterior dislocation of hip is less common than posterior dislocation
• Usually follows traumatic injury and patient may have associated fracture of hip
• Patients are in severe pain and unable to weight bear
• Evaluation is done by diagnostic clinical examination and diagnostic imaging
• Closed reduction must be done within 6-12 hours for best outcome; delay worsens outcome
• If closed reduction unsuccessful or contraindicated (associated femoral fractures) operative open reduction and internal fixation is recommended