arthroplasty
Painful Total Hip Arthroplasty
advanced
6 min
18 marks
6 questions
Clinical Scenario
A 65-year-old male presents with progressive left groin pain 3 years after cemented THA for osteoarthritis. He initially had an excellent outcome with pain-free walking for 2 years. Now pain limits walking to 200m and disturbs sleep. He reports low-grade fevers. On examination, he walks with an antalgic gait, has limited hip rotation, and pain on axial loading.
AP pelvis radiograph showing left cemented THA with progressive radiolucent line >2mm around acetabular component, cup migration, and cement mantle fracture. Femoral component appears well-fixed.
Source: AI-Generated: Cemented THA Acetabular Loosening Educational Radiograph • OrthoVellum AI • OrthoVellum Educational Use
Questions
Question 1 (3 marks)
What are the key differential diagnoses for painful THA?
Question 2 (3 marks)
Describe your investigation approach including specific tests and thresholds.
Question 3 (3 marks)
Aspiration shows WCC 3,500/μL with 85% PMN. CRP is 25 mg/L. Cultures grow Staphylococcus epidermidis. How do you interpret these results and what are your management options?
Question 4 (3 marks)
If infection is excluded and CT shows significant acetabular osteolysis with 30% posterior column involvement, what is your management plan?
Question 5 (3 marks)
What factors influence your choice of acetabular reconstruction? Discuss the Paprosky classification.
Question 6 (3 marks)
What is the role of advanced imaging modalities in painful THA?
Exam Day Cheat Sheet
Must Mention
- •MUST EXCLUDE PJI before any revision
- •Groin pain = acetabular pathology (start-up, activity-related)
- •Thigh pain = femoral pathology
- •MSIS criteria: WCC >3000, PMN >80%, CRP >10, alpha-defensin positive
- •Two-stage revision for chronic PJI (85-95% success)
- •DAIR only for acute (<4 weeks) - NOT chronic
- •Paprosky classification guides reconstruction
Common Pitfalls
- •Antibiotics before aspiration
- •DAIR for chronic PJI
- •Missing infection (revision will fail)
- •Not getting comparison X-rays
- •Forgetting spine as pain source
Exam Tips
- →PJI threshold: WCC >3000/μL, PMN >80%
- →CRP threshold: >10 mg/L (chronic THA PJI)
- →ESR threshold: >30 mm/h
- →Two-stage success: 85-95%
- →DAIR success: 60-80% (acute only)
- →Radiolucent line >2mm = loosening
- →Alpha-defensin: 98% specificity