人工膝関節置換術後の大腿骨顆上骨折に対する逆行性髄内釘の使用経験

Use of a Retrograde Intramedullary Nail to Treat Femoral Supracondylar Fractures after Total Knee Replacement

　人工膝関節置換術後の大腿骨顆上骨折は時に見受けられる．今回われわれは逆行性髄内釘を用いて治療を行ったので報告する．1999年11月から2005年6月までに発生した人工膝関節置換術後の大腿骨顆上骨折5例を対象とした．全例女性で全例関節リウマチ膝であった．人工膝関節は全例Nexgen，MG Ⅱ，CRが施行されており，3例に対しSmith and Nephew社製Supracondylar nail，2例に対しSynthes社製Distal femoral nailを使用した．全例骨癒合が得られ，術後平均ガンマ角は＋0.6°であった．骨折部の伸展変形を防ぐには術前に大腿骨インプラントの顆間窩の幅と髄内釘の直径を検討する必要がある．

　Femoral supracondylar fractures are relatively common after total knee replacementing (TKR), and we heve been treating them by fixation with a retrograde intramedullary nail. The cases in this report were treated for femoral supracondylar fractures between November 1999 and June 2005. All of the patients were female and had been diagnosed with rheumatoid arthritis. The initial treatment in every case was posterior-cruciate-retaining TKA (Nexgen, MG Ⅱ, CR；Zimmer). A supracondylar nail (Smith and Nephew) was used to treat 3 cases of supracondylar fracture, and a distal femoral nail (Synthes) was used in 2 cases. Bone fusion was achieved in every case. The average angle between the distal shaft of the femur and a line drawn perpendicular to the distal surface of the femoral component (gamma angle) was ＋0.6°. It was concluded that it is important consider the interbicondylar width of the femoral implant and the central diameter of the nail when performing this procedure.