During revision total hip arthroplasty, the femoral component is found to be well-fixed with extensive bone loss around the proximal femur. According to the Paprosky classification, a Type IIIB femoral defect is characterized by:
- A Calcar loss only with intact metaphysis and isthmus
- B Metaphyseal destruction with less than 4 cm of intact diaphyseal bone available ✓
- C Metaphyseal destruction with 4–7 cm of intact isthmus available
- D Complete femoral discontinuity requiring allograft reconstruction
Explanation
The Paprosky femoral defect classification guides revision implant selection: Type I has minimal bone loss; Type II has metaphyseal damage with intact isthmus; Type IIIA has metaphyseal destruction but ≥4 cm of intact diaphysis for scratch-fit fixation; Type IIIB has <4 cm of intact diaphysis, often necessitating distal femoral fixation with a modular or reconstruction femoral implant, or proximal femoral replacement. Type IV represents a complete defect. Distinguishing IIIA from IIIB is critical because IIIB typically requires longer stems with distal purchase or proximal femoral allograft-prosthesis composites.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.