What are the criteria for deciding between hemiarthroplasty and total arthroplasty for hip joint replacement?

Criteria for Deciding Between Hemiarthroplasty and Total Hip Arthroplasty

For patients with unstable (displaced) femoral neck fractures, total hip arthroplasty (THA) may provide better functional outcomes compared to hemiarthroplasty, but comes with a higher risk of complications. 1

Patient Factors to Consider

Age

• Age 50-64 years: Strong indication for THA 2
• Age >80 years: Strong indication for hemiarthroplasty 2
• Ages 65-80: Decision requires consideration of additional factors below

Functional Status and Activity Level

• Independent functional status: Favors THA
• Dependent functional status: Favors hemiarthroplasty 2
• Higher activity level with greater demands on the hip joint: Favors THA

Comorbidities

• Significant comorbidities (ASA class 3-4, DNR status): Higher risk of complications with hemiarthroplasty 2
• Specific conditions favoring hemiarthroplasty:
  • Hemiplegia
  • Dialysis dependence
  • Underweight status 2
• Conditions with higher THA complication risk:
  • Disseminated cancer
  • Diabetes 2

Fracture Characteristics

Fracture Type

• Unstable (displaced) femoral neck fractures: Both THA and hemiarthroplasty are appropriate, with specific selection criteria 1
• Intracapsular fractures:
  • Undisplaced: Internal fixation with screws or sliding hip screw 1
  • Displaced: Hemiarthroplasty or THA based on patient factors 1
• Extracapsular fractures: Typically managed with sliding hip screw or intramedullary nail, not arthroplasty 1

Long-term Considerations

Risk of Acetabular Erosion

• Concern for acetabular erosion: Favors THA
• Low conversion rate: Only 2.3% of hemiarthroplasties require conversion to THA within 5 years 3
• Timing of conversions: 63% of conversions occur within the first year 3
• Most common reason for conversion: Degenerative changes (67.6%) 3

Quality of Life Impact

• THA may provide better functional outcomes but with increased risk of complications 1
• Younger patients (<75 years) have 1.64 times higher odds of requiring conversion from hemiarthroplasty to THA 3

Decision Algorithm

1. First, assess patient age:

   • <65 years: Consider THA as first option

   • 80 years: Consider hemiarthroplasty as first option

   • 65-80 years: Proceed to next steps

2. Evaluate functional status and activity level:

   • Independent, active: Favor THA
   • Dependent, limited mobility: Favor hemiarthroplasty

3. Assess comorbidities:

   • Multiple comorbidities or high surgical risk: Consider hemiarthroplasty
   • Few comorbidities with good surgical candidacy: Consider THA

4. Consider fracture pattern:

   • Ensure fracture type is appropriate for arthroplasty (typically displaced femoral neck fractures)
   • Extracapsular fractures generally require fixation, not arthroplasty

Important Considerations

• Cemented femoral stems are recommended for both THA and hemiarthroplasty in hip fracture patients 1, 4
• Surgical approach should be based on surgeon experience and patient anatomy, though direct anterior approach may offer advantages for early mobilization 5
• Preoperative planning is essential, including appropriate radiographic evaluation 4

Common Pitfalls to Avoid

1. Overusing THA in very elderly, low-demand patients with limited life expectancy
2. Choosing hemiarthroplasty for younger, active patients who may experience acetabular erosion
3. Failing to consider patient's pre-fracture functional status in decision-making
4. Not discussing the risks and benefits of each approach with patients and families
5. Overlooking the importance of cemented stems in elderly patients with osteoporotic bone

Remember that while THA may provide better functional outcomes, the low conversion rate from hemiarthroplasty to THA (2.3% over 5 years) suggests that hemiarthroplasty remains a durable solution for appropriately selected patients 3.