Asymmetric bilateral hip dislocation in young man: a case report.

Bilateral hip dislocation is a rare event, asymmetric dislocation is even rarer. Due to the intrinsic stability of the hip joint this lesions usually follow a high energy trauma. Because of the common associated lesions, the initial clinical assessment should be performed thoroughly. CT scan rather than x-rays offers a complete survey of these possible associated injuries such as thoracic or abdominal bleedings, neurologic lesions or fractures directly associated with the hips dislocations. The first goal should be reduction of the dislocation to prevent avascular necrosis (AVN) of the femoral head and arthritis. We report a case of a young man with right anterior hip dislocation and left posterior hip dislocation with associated fracture of the posterior wall.

Introduction

Usually hip dislocations occur after traumatic injury and 85-90% of these are posterior dislocations (1). Bilateral dislocations account for 1% of all hip dislocations (2). In the English-language literature only 29 documented cases of this dislocation pattern can be found (3-9).

Case report

A 23 year-old male had a car accident at approximately 70 km/h. He was brought at the emergency department (E.D.) within 2 hours after the accident. At the arrival he was hemodynamically stable but with a GCS=3. He reported several abrasions all over the body and had evident deformations of both lower extremities. The left hip was shortened, adducted and internally rotated, the other one was shortened, abducted, externally rotated and flexed at 30°. Both the extremities had limited range of motion (the former limited external rotation, the latter limited internal rotation). The lower limbs were warm and the peripheral pulses were strong and symmetrical.

Initial imaging included computer tomography (CT) of brain, thorax, abdomen and pelvis.

CTs were negative for hemorrhages but revealed a fracture of the left clavicle and an asymmetric bilateral hip dislocation.

The right hip was anteriorly dislocated with no associated fractures. The left hip was posteriorly dislocated with a fracture of the posterior wall (Fig. 1)

Figure 1.

Preoperative TC

The right hip was successfully reduced in the E.D. whereas the left one couldn’t be reduced with external maneuvers (Fig. 2). In the following days the patient was diagnosed with diffuse axonal injury with a series of encephalic CT scans.

Figure 2.

TC after reduction Right Hip

In consequence of the neurological condition the left hip was surgically reduced and the fracture of the left pelvis fixed fifteen days later together with the clavicle fracture. The posterior wall fracture was fixed with two plates using a posterior approach.

A new pelvis radiograph showed the good outcome of the operation (Fig. 3).

Figure 3.

Post-op x-rays

On a pelvis radiograph taken 6 months after the accident the right hip showed no pathological signs whereas the left one showed signs of necrosis of the femoral head (Fig. 4). Because of the neurological situation a clinical assessment could not be performed.

Figure 4.

Six months follow up x-rays

Discussion

Due to the intrinsic stability of the hip joint this type of lesions are usually caused by a high energy trauma such as a car or motorbike accident (10-14).

The hip joint bases his stability on different elements like the depth of the acetabulum increased by the labrum, a thick capsule and a strong group of muscles. There’s also an efficient ligamentous system represented by the capsular ligaments and the teres ligament.

Usually these types of lesions are caused by a dashboard injury (15). A crash with an abducted hip leads to an anterior dislocation whereas an impact with an adducted hip cause a posterior dislocation (16, 17-19).

Associated injuries are always to be looked for carefully. They include femoral fractures (shaft, neck, heads), pelvis and acetabular fractures, fractures of knee, ankle and foot (20-22).

Abdominal, chest and head injuries are also reported to be associated with hip dislocations (22-25), similar to our patient who reported a diffuse axonal injury and a fracture of the left clavicle.

Clinical examination is the most important element to diagnose a hip dislocation.

In a posterior dislocation the hip is internally rotated, flexed and adducted whereas in an anterior dislocation the hip is externally rotated and abducted. A plain radiography of the pelvis is enough to confirm the diagnosis but with a computed tomography associated fractures can be fully examined.

The reduction of the dislocation must be performed as soon as possible to prevent complications such as avascular necrosis (AVN) the incidence of which increases if the reduction is delayed (23).

A closed reduction should always be the first choice unless there are associated hip or pelvis fractures.

A surgical approach is chosen in cases of irreducible dislocation or non concentric reductions.

Usually in posterior dislocations a Kocher-Langenbach approach is used, anterior dislocations are addressed with an anterior or antero-lateral approach (26). In addition to provide a concentric a stable reduction is important to remove intra-articular bone or cartilage fragments that interpose between the articular surfaces. An arthroscopic approach can be used if the only aim is to remove little fragments without fixing them. After closed reduction weight bearing should be avoided for only 2 weeks starting mobilization as soon as the pain permits (27).

Hip mobilization should be started immediately and weight bearing allowed after 6-8 weeks.

Poorer outcomes are associated with posterior dislocations, associated injuries and a delayed time of reduction (>6 hours) (1, 28-30).

All these elements may have an effect in causing AVN and arthritis which are associated to poor clinical outcomes.

Conclusions

In the case reported the right hip was treated early with closed reduction and at 6 months x-rays shows no pathological signs, for the left one an open reduction and internal fixation were performed after fifteen days because of major neurological problems and at 6 months x-rays shows clear signs of AVN. The time of reduction and the associate lesions could explain the different outcome between the two hips.