皆川 洋至

Hiroshi MINAGAWA

城東整形外科

Joto Orthopedic Clinic

キーワード : muscle, US elastography, compartment syndrome

筋は，運動器構成体の中で唯一能動的に硬さを変えながら機能し，日常生活やスポーツ活動に大きく関わる組織である．整形外科臨床においては，筋の廃用性萎縮によって生じる転倒，オーバーユースを基盤に生じる肉ばなれ，腱断裂，腱炎，腱鞘炎，さらに筋による関節の衝撃干渉作用低下が引き起こす疲労骨折など様々な疾患の病態に深く関わる．筋の硬さを客観的に定量評価する臨床的意義は大きく，これまで触診，関節可動域，筋硬度計によって評価が試みられてきた．しかし，触診は客観性に乏しく，関節可動域は必ずしも筋の硬さを反映せず，筋硬度計は皮膚表面から深部全体の硬さしか表現できない欠点があった．一方，超音波エラストグラフィでは筋の硬さを客観的に可視化して表現できるため，近年様々な基礎研究，臨床応用が始まった．筋が極端に硬くなるコンパートメント症候群は，筋内圧の著しい上昇が引き起こす疾患であり，ときに重篤な後遺障害を残す．一般に針を直接筋へ刺入し内圧を測定して診断するが，超音波エラストグラフィでは非侵襲的に筋の硬さを評価でき，鍼治療や筋膜切離による除圧効果の確認，術後の経時的評価にも威力を発揮する．超音波エラストグラフィは，疾患の診断や病態把握，治療効果判定ばかりでなく，傷害の予防にも役立てる試みがなされている．

Although palpation, joint range of motion, and measurement by hardness meter are used to represent muscle hardness, all of them have some weak points. Palpation is easy and cost-effective, but it is a subjective method. Joint range of motion may represent muscle hardness indirectly, but it is influenced by bony abnormalities, tight capsule, shortening of the ligament, and adhesion of the joint. Hardness meter is an objective method, but it measures the total hardness under skin tissue. US elastography produces a two-dimensional hardness map, so we can measure the hardness of each muscle. Compartment syndrome is characterized by severe pain and extremely hard muscles caused by high intra-muscular pressure. Delayed diagnosis and treatment are known causes of severe physical impediment. US elastography made it possible to visualize the affected muscles, allowing us to perform selected fasciotomy with small skin incision and intra-operative monitoring under US elastography. As muscle hardness changes with the status of activities of daily living and sports, knowing muscle hardness may be useful for improving performance and avoiding injuries associated with daily and sports activities.