In a total knee arthroplasty, failure due to polyethylene insert wear leading to progressive osteolysis is caused by which mechanism primarily?

• A Adhesive and abrasive wear generating sub-micron polyethylene particles that activate macrophage-mediated osteoclastogenesis via RANKL upregulation ✓
• B Corrosion of the metallic tibial baseplate causing ionic toxicity and direct osteocyte death
• C Bacterial biofilm formation on polyethylene promoting an inflammatory cascade and bone resorption
• D Mechanical fatigue of polyethylene causing gross delamination that mechanically strips the cement mantle

Explanation

Polyethylene wear debris (submicron particles generated by adhesive, abrasive, and fatigue wear) is phagocytosed by macrophages. This activates NF-κB pathways and cytokine release (TNF-α, IL-1β, IL-6), which upregulate RANKL expression on osteoblasts and stromal cells. RANKL-RANK interaction drives osteoclast differentiation and activation, producing progressive periprosthetic osteolysis — the so-called 'particle disease' or 'biological loosening.' This ultimately leads to component loosening without infection. This is distinct from septic loosening (bacterial biofilm, option C) and mechanical fatigue delamination (option D), which is a different wear mode but not the primary osteolysis mechanism.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.