MRIでbone marrow edema（BME）パターンを呈した膝タナ障害の2例

Bone Marrow Edema Pattern of MRI Induced by Shelf Syndrome. Report of Two Cases

　MRIで骨髄浮腫（bone marrow edema：BME）パターンを呈したタナ障害の2例を経験したので報告する．両症例ともに打撲を疑わせる皮下斑状出血はなく，主症状は膝蓋大腿関節内側の圧痛であり，初診時MRIで膝蓋内側滑膜ヒダ（タナ）と内側顆非荷重面においてT2強調冠状断像でBMEパターンを呈していた．関節鏡で同部の陥凹や軟骨損傷を認めた．術後は症状が消失し，スポーツ復帰した．術後のMRIにおいてBMEパターンは消失していた．タナ障害の中でも高度に肥厚したものは，骨髄内に輝度変化を生じるほどの障害を与える可能性があることが示唆されるため，タナを切除する必要がある．

　We report two cases of shelf syndrome with a bone marrow edema (BME) pattern on the MRI scans. Patient 1 was a 17-year-old woman who complained of bilateral knee pain. Physical examination revealed tenderness of the medial aspect of both knees in the vicinity of the patella. MRI showed a medial shelf and BME pattern in the non-weight bearing medial femoral condyle of both knees. Arthroscopic examination revealed cartilage damage and fibrillation about the surface of impingement in flexion corresponding to the BME pattern area. The shelf was resected, and the patient's symptoms were completely relieved. Patient 2 was a 15-year-old man who complained of right knee pain. Physical examination revealed tenderness of the medial aspect of his right knee in the vicinity of the patella. The ROM of the right knee was 100 degrees in flexion. MRI and an arthroscopic examination revealed the same findings as in Patient 1. The shelf was resected, and the patient's symptoms completely resolved. He has acquired a full ROM in flexion.