The Exeter polished collarless tapered femoral stem achieves long-term cemented fixation primarily through which mechanism?
- A Mechanical interlock of its matte surface texture with the cement mantle
- B Controlled subsidence within the cement mantle, converting axial load into uniform radial compression at the cement-stem interface ✓
- C Biological osseointegration across the cement mantle through stress-shielded zones
- D Collar-mediated transmission of compressive load directly onto the calcar femorale
Correct answer: B. Controlled subsidence within the cement mantle, converting axial load into uniform radial compression at the cement-stem interface
Explanation
The Exeter stem is deliberately polished, collarless and double-tapered. It is designed to subside a small distance within the PMMA mantle, and the taper geometry converts this axial movement into hoop and radial compressive stresses that lock stem to cement, a force-closed system. This contrasts with the Charnley concept of shape-closed fixation using a matte surface and a collar, making options A and D descriptions of the wrong philosophy.
Reference: Miller's Review of Orthopaedics, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.