How should a suspected hip subluxation in an elderly woman be evaluated and managed?

Hip Subluxation in an Elderly Woman: Evaluation and Management

If you suspect hip subluxation in an elderly woman, immediately obtain plain radiographs (AP pelvis and lateral hip) as your initial imaging, and if these are negative or equivocal despite high clinical suspicion, proceed directly to MRI or CT to rule out occult fracture. 1

Initial Evaluation

Immediate Clinical Assessment

Look for these specific findings that differentiate subluxation from fracture:

• Leg length discrepancy (suggests subluxation or fracture)
• Shortened and externally rotated lower extremity (classic for hip fracture) 2
• Minimal or no limitation of hip abduction (more consistent with subluxation than dislocation) 3
• Trendelenburg gait in ambulatory patients (suggests subluxation) 3
• Palpable dorsalis pedis pulse and intact sensation (rule out vascular/nerve injury) 2

Imaging Algorithm

Step 1: Plain Radiographs (Always First)

• AP pelvis and lateral hip views are mandatory initial imaging 1
• These are rapidly obtained, well-tolerated, and diagnostic in most cases
• If radiographs show clear fracture, proceed directly to surgical planning

Step 2: Special Positioning View for Subluxation If radiographs suggest subluxation rather than complete dislocation, obtain an abduction-internal rotation (AIR) view:

• Position: hips abducted ≥45° with internal rotation 3
• In true subluxation: femoral head relocates into acetabulum with perfect or near-perfect reconstitution of Shenton's line
• In true dislocation: femoral head fails to relocate 3
• This single view prevents overdiagnosis and avoids unnecessary invasive procedures

Step 3: Advanced Imaging if Radiographs Negative/Equivocal

• MRI without contrast is the gold standard for occult fractures 1
• CT is acceptable alternative if MRI contraindicated
• Do not delay—occult hip fractures have same mortality risk as visible fractures

Critical Pitfall: Don't Miss the Fracture

The most dangerous error is assuming "just subluxation" when an actual fracture exists. In elderly patients:

• 95% of hip fractures occur in patients >60 years 4
• 90% result from simple falls in osteoporotic bone 4
• Delays in diagnosis increase mortality, complications, and hospital stay 1

If any doubt exists after plain films, obtain MRI immediately—do not observe.

Management Pathway

If True Subluxation (No Fracture)

Based on the AIR view confirming reducible subluxation 3:

• Ilfeld abduction splint for immobilization
• No need for general anesthesia, arthrography, traction, or spica casting 3
• Protected weight-bearing for 2-6 weeks (most commonly prescribed) 5
• Physical therapy focusing on hip stabilizers

If Hip Fracture Confirmed

Follow AAOS 2022 guidelines 6, 2:

Timing: Surgery within 24-48 hours of hospital admission (moderate strength recommendation)

• Data from high-volume centers show improved outcomes within 24 hours
• 24-48 hour window accounts for variation in facility resources
• Goal: surgery as soon as safely possible 6

Interdisciplinary Care (strong recommendation):

• Immediate hospitalist/orthogeriatrics consultation in ED 2
• This decreases complications and improves outcomes 6

Surgical Approach for Displaced Femoral Neck Fracture:

• Arthroplasty (hemiarthroplasty or total hip) is recommended 2
• Cemented femoral stem (strong recommendation) 6, 7
• Approach: anterolateral or direct anterior preferred (lower dislocation risk than posterior) 2
• Anesthesia: either spinal or general is appropriate 2

For Intertrochanteric Fractures:

• Cephalomedullary device for unstable fractures 7

Tranexamic Acid: Use to reduce blood loss and transfusion requirements 7

Pre-operative Optimization

Check these specific parameters 4:

• Hemoglobin: If <9 g/dL, or <10 g/dL with ischemic heart disease, consider pre-operative transfusion
• Potassium: Correct hypokalaemia (risk of rapid AF)
• ECG: Required in all elderly hip fracture patients
• INR: Must be <2 for surgery, <1.5 for neuraxial anesthesia if on warfarin 4

Post-Fracture Secondary Prevention

After any hip fracture or confirmed subluxation, initiate fracture liaison service evaluation 8:

Immediate Non-Pharmacological:

• Calcium 1,200 mg/day (age >51 years) 9
• Vitamin D 800 IU/day 9, 8
• Smoking cessation and alcohol limitation 8
• Fall prevention strategies

Pharmacological Treatment (strong recommendation) 8:

• First-line: Alendronate or risedronate (oral bisphosphonates)
  • Well-tolerated, low cost, extensive experience
  • Reduce vertebral, non-vertebral, and hip fractures by ~50% over 3 years
• Alternatives if oral intolerance/dementia/non-compliance:
  • Zoledronic acid (IV annually)
  • Denosumab (subcutaneous every 6 months)
• For very severe osteoporosis: Teriparatide (anabolic agent)

Duration: 3-5 years, longer if high risk persists 8

Key Distinction: Post-Surgical Subluxation

If subluxation occurs after hip fracture surgery (rare complication):

• Most cases associated with sepsis 10
• Occurs 2-26 months post-operatively for subluxation 10
• 10 days to 9 weeks for frank dislocation 10
• Treatment options: implant removal, resection arthroplasty, or revision arthroplasty 11, 10

This is fundamentally different from acute traumatic subluxation and requires surgical consultation.