During revision total knee arthroplasty, the orthopedic surgeon finds significant bone loss of the proximal tibia. According to the Anderson Orthopaedic Research Institute (AORI) classification, bone loss that is contained within the metaphysis without cortical compromise is classified as:

• A Type I
• B Type IIb
• C Type III
• D Type IIa ✓

Explanation

In the AORI classification for bone defects at revision arthroplasty, Type I represents minor bone defects with an intact metaphysis, Type IIa involves defects in one condyle/compartment within the metaphysis, Type IIb involves both condyles/compartments, and Type III denotes deficient metaphyseal bone with possible ligamentous instability. Defects contained within the metaphysis without cortical breach affecting one compartment are Type IIa. This guides implant selection from augments to structural allografts.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.