Can an unstable pelvis present with extremity shortening and rotation?

Unstable Pelvic Fractures and Extremity Shortening/Rotation

Yes, an unstable pelvic fracture can present with extremity shortening and rotation, which are important clinical signs that should prompt immediate evaluation for pelvic ring disruption. 1

Clinical Presentation of Unstable Pelvic Fractures

Unstable pelvic fractures typically present with the following signs:

• Limb shortening: Due to displacement of the hemipelvis, causing apparent shortening of the affected lower extremity 1
• External rotation: The affected limb often appears externally rotated due to the loss of normal pelvic architecture 1
• Pain: Localized to the pelvis, suprapubic area, or inner thigh, often exacerbated by movement 2
• Inability to bear weight: Patients typically cannot ambulate due to pain and mechanical instability 1

Types of Unstable Pelvic Fractures Associated with Limb Deformity

According to the World Journal of Emergency Surgery guidelines, the following pelvic fracture patterns are most commonly associated with limb shortening and rotation:

1. Rotationally unstable fractures:

   • Anteroposterior compression type II/III ("open book" injuries)
   • Lateral compression type II/III ("windswept pelvis") 1

2. Vertically unstable fractures:

   • Vertical shear injuries
   • Combined mechanism injuries 1, 3

Biomechanical Basis for Deformity

The deformity occurs because:

• The posterior sacroiliac complex contributes more to pelvic ring stability than anterior structures 3
• When this complex is disrupted, the hemipelvis can migrate superiorly and rotate externally 3
• The strong hip abductor and external rotator muscles pull the unstable hemipelvis in a cephalad and externally rotated position 1

Diagnostic Approach

When extremity shortening and rotation are present:

1. Physical examination: Look for a shortened, externally rotated lower extremity (as noted in case examples) 1
2. Radiographic evaluation:
   • AP pelvis radiograph to assess pelvic ring disruption
   • Lateral hip radiograph to evaluate for associated femoral fractures 1
3. CT scan: To fully assess posterior pelvic ring involvement and degree of displacement 1

Management Implications

The presence of extremity shortening and rotation indicates:

• Need for urgent stabilization: To prevent further hemorrhage and neurological or visceral injury 4
• Consideration for pelvic binder: As a temporary measure to reduce pelvic volume and provide initial stabilization 1
• Surgical fixation: Most unstable pelvic fractures with deformity require definitive internal fixation 1

Pitfalls and Caveats

• Don't confuse with hip fracture: Femoral neck fractures can also present with shortening and external rotation but require different management 1
• Assess for associated injuries: Unstable pelvic fractures with deformity are typically caused by high-energy trauma with potential for multiple injuries 5
• Consider hemodynamic status: Unstable pelvic fractures with deformity may be associated with significant hemorrhage requiring urgent intervention 1
• Elderly patients: Even minor trauma can cause significant pelvic fractures in the elderly due to bone fragility 1

Treatment Algorithm

1. Initial stabilization: Apply pelvic binder for temporary stabilization if unstable pelvic fracture is suspected 1
2. Hemodynamic assessment: Prioritize resuscitation for unstable patients 1
3. Definitive fixation: For unstable fractures with deformity, surgical fixation is typically required:
   • Anterior fixation (pubic symphysis plating) for "open book" injuries 1
   • Posterior fixation for vertically unstable fractures 1
   • Combined anterior and posterior fixation for complex unstable patterns 1

In summary, extremity shortening and external rotation are classic signs of unstable pelvic fractures that require prompt recognition and appropriate management to reduce morbidity and mortality.