A 72-year-old woman with severe bilateral osteoarthritis of the hip undergoes total hip replacement. Six months postoperatively she has a painful, warm, erythematous hip with raised CRP and elevated ESR. Aspiration reveals 50,000 WBC/mm³ with 90% neutrophils. The most likely diagnosis is:
- A Heterotopic ossification causing impingement
- B Aseptic loosening of the prosthesis
- C Periprosthetic joint infection ✓
- D Trochanteric bursitis from surgical approach
Correct answer: C. Periprosthetic joint infection
Explanation
Periprosthetic joint infection (PJI) is the most serious complication of joint replacement surgery and must be excluded in any painful replaced joint. A synovial WBC count above 3,000 cells/mm³ (in hip) with greater than 80% polymorphonuclear leucocytes is highly specific for infection per MSIS criteria. Treatment typically requires two-stage revision surgery — removal of all implants, a cement spacer with antibiotics, and reimplantation after infection clearance — or one-stage revision in selected cases.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.