上腕骨大結節骨折に対する8の字鋼線締結法後に，裂離型大結節骨折を生じた1例

Avulsion Fracture of the Facet of Insertion of the Supraspinatus Muscle, after the Operation of Tension Band Wiring to Fracture of the Greater Tuberosity of the Humerus. Case Report

　肩関節前方脱臼骨折に伴う上腕骨大結節骨折に対し，軟鋼線による8の字鋼線締結法を施行後に，裂離型大結節骨折を生じたため再手術に至った1例を経験したので報告する．本症例は，本来骨密度の低い大結節の骨折に，脱臼骨折に伴う血行障害と骨膜損傷を来したことで骨脆弱性が進行し，裂離型大結節骨折を生じたものと考えた．本骨折の術後に早期からの骨萎縮像を認めた場合には同部位の裂離骨折を生じる可能性が示唆された．

　We report a case (72-year-old female) of an avulsion fracture of the facet of insertion of the supraspinatus muscle that required a second operation.　The fracture occurred after the initial surgery to fix a displaced greater tuberosity to the humeral shaft with a soft wire during treatment of a fracture of the greater tuberosity associated with anterior dislocation of the shoulder.　The avulsion fracture of the facet is thought to have been attributable to preexisting low bone mineral density of the greater tuberosity and aggravation of the bone fragility by both the impaired blood flow and extensive periosteal tear caused by the fracture-dislocation.　The second operation was performed as the rupture of the supraspinatus muscle.　This case suggests that postoperative bone fragility may predispose to an avulsion fracture of the facet of insertion of the a rotator cuff muscle.