An 81-year-old woman falls onto the operated leg 6 years after total knee replacement. Radiographs show a displaced fracture of the tibial shaft beginning just distal to the tip of a well-fixed cementless tibial stem. According to the Felix classification, this periprosthetic tibial fracture is:
- A Type I, involving the tibial plateau
- B Type II, involving the metaphysis adjacent to the implant
- C Type III, in the shaft distal to the implant ✓
- D Type IV, involving the tibial tubercle
Correct answer: C. Type III, in the shaft distal to the implant
Explanation
The Felix classification divides periprosthetic fractures about the tibial component into four types: type I involves the tibial plateau, type II the metaphyseal region adjacent to the stem, type III the diaphysis distal to the implant, and type IV the tibial tubercle. A fracture starting at the stem tip and extending into the shaft is therefore type III. Each type is further subdivided into A, B, and C depending on implant fixation and timing.
Reference: Miller's Review of Orthopaedics, 8th ed.
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Written and medically reviewed by the StethoPrep medical team.