Please interpret the radiograph and tell me what you are concerned about in this patient?

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An AP pelvic radiograph is presented in a 47-year-old female. There is evidence of left native hip dislocation. There limb appears to be significantly shortened and in external rotation. There is no obvious associated fracture of the femoral head or acetabulum. I would want further orthogonal views with a lateral radiograph of the hip to assess the direction of dislocation.

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Key Concerns

1. High energy injury - ATLS Principles

2. Dislocation requiring urgent reduction

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How would you manage this patient?

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ATLS

“This patient has a likely high energy injury mechanism; I would therefore ensure that the patient was managed via ATLS principles. With a trauma call, introduction of team members and assignment of roles followed by a primary and secondary survey to identify and treat any life / limb threatening injuries.”

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History

• A               Allergies

• M              Medication

• P               Past medical history

• L               Last ate

• E               Events

  • ?Previous dislocations

  • Paraesthesia / numbness

  • Other injuries / Pain anywhere else

 

Examination

• Position of limb

  • Shortened externally rotated - anterior dislocation

  • Adducted, flexed, internally rotated - posterior dislocation

• NV status

  • Examine for sciatic nerve function

 

Investigation

• XR:

  • AP + Lateral Hip

  • AP Pelvis

 

Management

 

• Surgical emergency

• Initial attempt at Closed reduction in ED with sedation

• Closed / Open reduction in theatre if unable to perform in ED

• Escalate to senior

 

“This patient has a native hip dislocation + paraesthesia. This will need emergency closed reduction in ED under sedation. If unable to reduce, then I would escalate to consultant and book patient into theatre for emergency closed / open reduction.”

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You are unable to reduce the hip and your consultant asked you to take patient to theatre overnight for reduction. How would you reduce the hip? 

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Preparation

• Explain procedure + gain consent

• Resus with monitoring

• Adequate sedation + muscle relaxation by appropriately trained individual

 

1. Bigelow Manoeuvre

   • Axial traction

   • Internal rotation + adduction

2. Allis Manoeuvre

   • Knee flexed to 90 degrees

   • Hip flexed to 90 degrees (relaxes hamstrings)

   • Longitudinal traction in direction of long axis of femur

   • Adduction + internally rotation if required

 

KEY TO REDUCTION = counter-traction from assistant who places down firmly on both ASIS

 

Note: MUSCLE relaxation may be key to reduction in these patients. Need to ensure discussed with anaesthetist at brief. 

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Following reduction how would you examine the patient and what imaging would you request?

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Post-reduction

• Check N+V status

• Check XR

  • AP + Lateral

• CT Pelvis​

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Why would you request a CT pelvis following native hip reduction?

 

High energy mechanism, order CT to exclude other injuries:

• Femoral head # (Pipkin fracture)

• Acetabular #

• NOF #

• Loose bodies in hip joint

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What are the complications of a native hip dislocation?

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Complications

• A significant amount of force is required to dislocate a native hip - therefore these are high energy injuries

• Associated injuries of the acetabulum and femoral head are common and should be assessed for following reduction with a CT pelvis + hip.

• Associated injuries / complications include:

  • Acetabular fracture

  • Femoral head / NOF#

  • Neurological Injury

  • Recurrent dislocation

  • AVN

    • Due to traction + disruption of retinacular vessels during process of dislocation / reductio

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On examination of the patient how would you differentiate an anterior from a posterior hip dislocation?

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Anterior Hip Dislocation

• Accounts for 10% of dislocations

• Limb will appear shortened and externally rotated

• Femoral nerve at risk

 

Posterior Hip Dislocation

• Accounts for 90% of dislocations

• Limb will appear shortened, adducted and internally rotated

• Sciatic nerve at risk

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What neurovascular structures are at risk with an anterior versus posterior hip dislocation?

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Anterior = Femoral nerve

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Posterior = Sciatic nerve

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What injuries must be evaluated for with dashboard type injuries? 

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• Posterior hip dislocation

• Patella #

• Femoral shaft #

• Femoral head (pipkin)

• Posterior wall acetabular fracture

• Sciatic nerve injury

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Following successful reduction of a native hip dislocation - would you follow this patient up in clinic? Why? 

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Patients with a native hip dislocation should be followed up in clinic for at least 2 years as they have high risk of Avascular Necrosis

• Due to traction + disruption of retinacular vessels during dislocation

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What would be signs that AVN was developing on the follow up radiographs?

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Evidence of:

• Femoral head sclerosis

• Fragmentation of femoral head 

• Crescent sign

• Femoral head collapse

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These findings are suggestive of avascular necrosis of the femoral head and may warrant further management such as core decompression or total hip replacement

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Note: See image below for AVN femoral head example