A 55-year-old man developed a pseudoaneurysm of the popliteal artery after tibial valgization osteotomy performed for degenerative genu varum. A tourniquet was used for the procedure. A wedge osteotomy was performed two centimeters under the joint line; the correction angle was ten degrees. Immediately after the end of the procedure, the distal pulses disappeared for ten minutes. Doppler exploration of the arterial network did not demonstrate any anomaly. Ten days postoperatively, the patient complained of sudden onset pain in the knee and tension in the popliteal fossa. Arteriography demonstrated a pseudo-aneurysm of the popliteal artery. The lesion caused an interruption of arterial flow and was successfully treated by emergency resection and suture.