What is the appropriate treatment for bilateral coxa profunda with acetabular protrusion and absent hip joint spaces?

Treatment of Bilateral Coxa Profunda and Acetabular Protrusion with Absent Hip Joint Spaces

Total hip arthroplasty (THA) should be performed for bilateral coxa profunda with acetabular protrusion and absent hip joint spaces, as the absence of joint space indicates end-stage osteoarthritis with radiographic evidence of structural damage requiring joint replacement. 1, 2

Rationale for Surgical Intervention

The absence of hip joint spaces represents complete cartilage loss and end-stage degenerative disease. According to EULAR guidelines, joint replacement must be considered in patients with radiographic evidence of hip OA who have refractory pain and disability 2. Similarly, ASAS/EULAR recommendations state that total hip arthroplasty should be considered in patients with refractory pain or disability and radiographic evidence of structural damage, independent of age 1.

The combination of coxa profunda, acetabular protrusion, and absent joint spaces creates a complex anatomical scenario that precludes conservative management or joint-preserving procedures.

Surgical Approach and Technical Considerations

Approach Selection

The direct anterior approach (DAA) has demonstrated excellent outcomes specifically for coxa profunda and protrusio acetabuli, with:

• Mean operative time under 60 minutes
• 97.70% survival rate for protrusio acetabuli
• 92.80% survival rate for coxa profunda
• Significant improvements in WOMAC scores (mean improvement of 34.89-40.38 points) and Harris Hip Score (mean improvement of 32.79-38.37 points) 3, 4

However, caution is warranted in obese patients, as each BMI unit adds approximately 0.9 minutes to operative time and may pose significant limitations 4.

Acetabular Component Management

For acetabular protrusion with absent joint space, the surgical technique must address:

1. Medial wall deficiency: Use impacted morsellised autograft with porous-coated cementless cups
2. Joint center restoration: Lateralize the acetabular component to restore anatomical hip mechanics
3. Bone grafting: Essential for achieving long-term fixation and preventing recurrence 5, 6

Uncemented cups with peripheral fixation (such as CLS expansion cups) combined with acetabular bottom grafting achieve superior outcomes compared to cemented components, with 90% achieving complete osteointegration by 6 months postoperatively 5, 6.

Critical Technical Goals

• Position the femoral component head inside the TAR triangle
• Lateralize the femoral head center to Köchler's line
• Achieve agreement between the approximate center of the femoral head and the center of the femoral component head
• In 159 of 188 cases, the medial border of the acetabular component should be transferred laterally to the ilioischial line to fully treat acetabular protrusion 4

Preoperative Optimization

Before proceeding with bilateral THA, address modifiable risk factors:

• Diabetes control: Optimize HbA1c to reduce adverse events 7
• BMI optimization: Elevated BMI increases adverse events and reduces patient-reported outcomes 7
• Smoking cessation: Required to minimize complications 7
• Narcotic weaning: Discontinue opioids preoperatively under physician guidance 7

Staging Considerations

For bilateral disease, stage procedures at 6-month intervals to allow adequate recovery and rehabilitation between surgeries 8. This approach has demonstrated favorable outcomes with reduced perioperative risk.

Common Pitfalls to Avoid

1. Attempting conservative management: With absent joint spaces, non-pharmacological treatments (exercise, weight reduction, assistive devices) and pharmacological interventions (NSAIDs, intra-articular injections) will not restore cartilage or modify disease progression 2

2. Using cemented cups without bone grafting: All failures in one series occurred in cemented acetabular cups implanted without bone grafting of the acetabular bottom 6

3. Inadequate lateralization: Failure to restore the hip center of rotation leads to biomechanical dysfunction and early failure

4. Underestimating complexity: Coxa profunda in women is associated with anterior acetabular dysplasia and thin acetabulum (mean thickness 3.9 ± 1.2 mm vs 7.5 ± 1.7 mm in controls), requiring careful preoperative planning 9

Expected Outcomes

With appropriate technique, expect:

• Leg length discrepancy >10mm in approximately 9-11% of cases 4
• Rare complications when performed by experienced surgeons familiar with the approach 4
• Mean follow-up Harris Hip Score of 85 with 90% achieving good or excellent results 5
• No radiological evidence of recurrence, osteolysis, or loosening at mid-term follow-up 5