In metal-on-metal (MoM) total hip bearings, the characteristic adverse tissue reaction causing pseudotumor formation is known as:
- A Giant cell reaction to polyethylene particles
- B Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) ✓
- C Heterotopic ossification
- D Transient osteoporosis of the hip
Correct answer: B. Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL)
Explanation
ALVAL (Aseptic Lymphocyte-dominated Vasculitis-Associated Lesion) is the characteristic histological pattern seen in adverse reactions to metal debris from MoM hip implants. Cobalt and chromium ions trigger a type-IV hypersensitivity response leading to periprosthetic tissue necrosis, cystic pseudotumor formation, and osteolysis. MoM bearings were largely withdrawn from the market due to this complication. Polyethylene particle reaction causes a giant cell macrophage response, not ALVAL.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.