Figure 1.

The knee indicated for medial unicompartmental knee arthroplasty (UKA). A 73‐year‐old woman complained of severe pain close to the medial knee joint line during walking for 2 years. The pain could not be relieved by tramadol, and so total knee arthroplasty (TKA) was carried out. (A) The antero‐posterior (AP) weight bearing X‐ray film showed K/L grade 4 in medial compartment, but only grade 1 in lateral compartment. (B) On lateral X‐ray film, the patellofemoral joint showed K/L grade 1 degeneration. Tibia plateau was classified as modified Keyes grade 1. This knee could be treated with medial UKA as an alternative to TKA.