eMedicine Specialties > Emergency Medicine > Trauma & Orthopedics
Dislocation, Hip: Differential Diagnoses & Workup
Updated: Dec 2, 2008
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Differential Diagnoses
Abdominal Trauma, Blunt
Fractures, Femur
Fractures, Hip
Fractures, Pelvic
Legg-Calve-Perthes Disease
Pediatrics, Limp
Workup
Laboratory Studies
No specific laboratory studies are indicated for hip dislocation. Laboratory studies should focus on the overall trauma workup and/or preoperative testing. Type and crossmatching of blood products is generally the most useful.
Imaging Studies
Radiography
A portable anteroposterior (AP) pelvis radiograph is often ordered as part of an initial trauma workup. The initial test should be a radiograph of the pelvis and hip. The presence of a hip dislocation can be subtle; however, a careful inspection of the AP pelvis radiograph should reveal most hip dislocations. Lateral views may further classify the type of dislocation.
- Findings on an AP pelvis radiograph
- The position of the femoral head relative to the acetabulum should be symmetrical. The joint space should be examined for bony fragments, widening, or evidence of an effusion.
- Both femoral heads should be roughly the same size. In a posterior dislocation, the femoral head may appear smaller than the contralateral side. This is because it is further away from the x-ray beam and is magnified less. The opposite is true of anterior dislocations.
- The positions of the trochanters in relation to the femoral shaft may reveal abnormal rotation.
- Shenton’s line is a smooth curved line defined by the obturator foramen and the femoral metaphysis. If this line is disrupted, a hip fracture, dislocation, or femoral neck fracture should be suspected.
- A thorough inspection of the film for associated fractures must be conducted.
- If the AP pelvis film is nondiagnostic and a high index of suspicion exists, a lateral hip film, dedicated hip films, Judet views, or CT scan may be indicated.
Computed tomography (CT) scan
A CT is an accurate test for diagnosing hip injuries except in patients with prosthetic hips where streak artifact obscures the image. A CT accurately delineates the type of dislocation as well as any accompanying fractures. CT scans of the pelvis are routinely obtained on major trauma patients. The information obtained by CT can be used in the emergency department and for long-term prognosis and management. If a CT scan is being performed to evaluate the abdomen and pelvis, the hip should be examined for pathology. However, a dedicated hip CT scan should not delay reduction. After the hip is reduced, a CT scan of the hip will provide valuable information to the orthopedist for further surgical or conservative management.
Magnetic resonance imaging (MRI)
MRI has a limited role in acute diagnosis and delineation of hip dislocations. Patients with multiple trauma are often unstable for MRI. It is time consuming and often unavailable. Once the patient is stabilized and the hip is reduced, MRI can provide valuable information about long-term management and prognosis.
Other Tests
- Radionucleotide scanning is a sensitive method that depicts early avascular necrosis (AVN).
- Radionuclide scanning is currently the criterion standard for diagnosis for AVN, though it is being replaced by MRI, which reveals greater anatomic detail and which appears to be equally sensitive.
Procedures
Reduction techniques are described as follows:
Allis method
The patient should be supine and under procedural sedation. The combined weight of the patient and physician may exceed the weight limit of the stretcher. It is generally unsafe for the physician to be standing on a stretcher. For these reasons, placing the patient on the floor rather than on the stretcher is often useful.
An assistant should stabilize the pelvis. The physician should initially be toward the patient’s feet, providing in-line traction. The physician should then gently flex the hip 60-90o while maintaining in-line traction. At this point, the physician is standing directly above the patient’s hip, providing traction in-line with the deformity.
Gently adducting the hip can force the head of the femur laterally and help it clear the acetabular rim. Alternately, gentle lateral traction can be applied to the proximal femur.
Reduction can be confirmed by a click that is felt and may be heard as well. The patient should assume normal anatomical position.
Stimson method
This method is mechanically the same as the Allis method, but the positioning is opposite. Although some physicians prefer this method because of its technical ease and high success rate, this method has some important disadvantages. It requires the patient to be in a prone position, which may not be possible for the patient with multiple trauma. Monitoring the patient during procedural sedation is also difficult.
The prone patient is placed so the pelvis on the affected side hangs either over the end or over the side of the stretcher. The hip and knee are flexed to 90o. Downward pressure is applied to the popliteal fossa, providing traction in-line with the deformity. An assistant stabilizes the pelvis and trunk preventing the patient from being pulled off the stretcher.
Whistler technique
The patient is placed supine with ipsilateral knee flexed to 120o. The physician stands on the affected side and places an arm under the ipsilateral knee with his or her hand resting on the contralateral knee. The pelvis and ankle are stabilized by an assistant or the physician’s free hand. The physician raises his or her arm, which applies an anterior force to the knee and subsequently to the affected hip.
Anterior dislocations
A modified Allis technique may be used. The patient is placed supine. The physician stands at the foot of the stretcher. Traction is applied to a neutral hip while an assistant stabilizes the pelvis. Gentle lateral traction applied to the proximal femur facilitates the femoral head clearing the acetabular rim.
Posterior dislocations
More on Dislocation, Hip |
| Overview: Dislocation, Hip |
 Differential Diagnoses & Workup: Dislocation, Hip |
| Treatment & Medication: Dislocation, Hip |
| Follow-up: Dislocation, Hip |
| Multimedia: Dislocation, Hip |
| References |
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References
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Further Reading
Keywords
hip dislocation, dislocation hip, traumatic hip dislocation, prosthetic hip dislocation, hip dysplasia, congenital hip dislocation, CDH, developmental dysplasia of the hip, DDH, hip fracture-dislocation
