What are the management options for a patient with suspected femoroacetabular impingement (FAI) given a low alpha angle and other potential knee or hip pathologies?

Management of Suspected Femoroacetabular Impingement with Low Alpha Angle

For patients with suspected femoroacetabular impingement (FAI) with a low alpha angle, MRI without contrast is the preferred initial diagnostic approach, followed by a comprehensive conservative management program for at least 3 months before considering surgical intervention. 1

Diagnostic Approach

Imaging

• MRI without IV contrast is the first-line imaging study for detailed evaluation of labral tears and chondral damage 1
• For more detailed labral assessment in subacute or chronic cases, MR arthrography may be preferred (90-95% sensitivity for labral pathology) 1
• High-resolution 3T MRI can improve visualization without requiring contrast 1
• Initial radiographs should include:
  • Orthogonal hip and pelvis X-ray views to assess bony morphology
  • Measurement of alpha angle (low in this case, suggesting non-cam type pathology)
  • Lateral center edge angle to evaluate for pincer-type morphology 2

Clinical Evaluation

• Assess for common FAI symptoms: groin pain, clicking, catching, buckling, stiffness, limited range of motion 3
• Perform specific clinical tests:
  • FADIR test (flexion, adduction, internal rotation) - positive impingement sign 2
  • Flexion abduction external rotation test 3

Conservative Management Protocol

First-Line Treatment (0-3 months)

1. Structured rehabilitation program:

   • Minimum 6-12 weeks
   • At least 3 sessions per week, 30+ minutes per session
   • Components: core strengthening, hip girdle muscle strengthening, aerobic activity, range of motion/stretching exercises 1
   • Individualized exercise progression every 1-2 weeks based on tolerance 1

2. Activity modification:

   • Implement pacing strategies ("small amounts often")
   • Avoid activities that exacerbate symptoms
   • Use appropriate and comfortable footwear 1

3. Pain management:

   • Paracetamol (up to 4g/day) as first-line analgesic for mild-moderate pain
   • NSAIDs for short-term pain relief if paracetamol is insufficient
   • Opioid analgesics only when other options are contraindicated, ineffective, or poorly tolerated 1

4. Patient education:

   • Information about FAI pathology
   • Activity modification and pacing
   • Addressing adverse mechanical factors
   • Setting realistic short-term and long-term goals 1

Assessment of Conservative Treatment Response

• Evaluate treatment response after 3 months of optimal conservative management
• Assessment should include:
  • Pain levels
  • Functional improvement
  • FAI-related quality of life 1
• Conservative treatment success rate: ~53-78% return to play in athletes who complete rehabilitation 1

When to Consider Advanced Imaging and Surgical Consultation

If symptoms persist despite 3 months of appropriate conservative management:

1. Consider advanced imaging (MR arthrography) to better visualize labral pathology 1
2. Refer for surgical consultation

Surgical Options (if conservative management fails)

Arthroscopic Intervention

• Labral repair is superior to debridement for long-term outcomes
  • Involves labral refixation with suture anchors into the acetabular rim
  • Often combined with correction of underlying pathology 1

Cartilage Procedures (based on lesion characteristics)

• Microfracture: For focal, contained lesions <4 cm² 1
• Mosaicplasty: For focal, full-thickness lesions <3 cm² in patients <45 years without osteoarthritis 1
• Osteochondral Allograft Transplantation (OAT): For larger defects (>2.5 cm²) or substantial loss of subchondral bone in patients ≤50 years 1

Important Considerations and Pitfalls

• Low alpha angle suggests this is not a typical cam-type FAI, requiring careful evaluation for alternative diagnoses 2, 4
• Consider other causes of hip pain with similar presentation:
  • Ischiofemoral impingement
  • Anterior inferior iliac spine/subspine impingement
  • Iliopsoas impingement 5
• Incidental labral tears are common in asymptomatic individuals and should be managed with appropriate clinical sensitivity 1
• Diagnosis should never be made on imaging alone but combined with clinical symptoms and examination findings 1
• Premature surgical intervention should be avoided, ensuring completion of a full 3-month conservative management program before considering surgery 1

Follow-up Protocol

• Regular follow-up (at least annually) to monitor:
  • Progression of symptoms
  • Development of early osteoarthritis
  • Functional status 1
• Adjust treatment plan based on patient response and functional goals 1