In vivo healthy knee kinematics during dynamic full flexion

Healthy knee kinematics during dynamic full �exion were evaluated using 3D-to-2D model registration techniques. Continuous knee motions were recorded during full �exion in a lunge from 85 ∘ to 150 ∘ . Medial and lateral tibiofemoral contacts and femoral internal-external and varus-valgus rotations were analy�ed as a function of knee �exion angle. e medial tibiofemoral contact translated anteroposteriorly, but remained on the center of the medial compartment. On the other hand, the lateral tibiofemoral contact translated posteriorly to the edge of the tibial surface at 150 ∘ �exion. e femur exhibited external and valgus rotation relative to the tibia over the entire activity and reached 30 ∘ external and 5 ∘ valgus rotations at 150 ∘ �exion. �inematics� data during dynamic full �exion may provide important insight as to the designing of high-�exion total knee prostheses

Interrelationship between myofiber type composition and intramuscular-fat content in muscles of Japanese Black cattle

黒毛和牛骨格筋における筋線維型構成と骨格筋内脂肪含量の関係について検討した．26－29カ月齢まで肥育された黒毛和牛より屠殺後，食肉生産上，重要な骨格筋である胸最長筋，大腿二頭筋，半膜様筋，半腱様筋，外側広筋，胸腹鋸筋および大腿直筋を摘出した．酵素組織化学的方法により筋線維をI型，IIA型およびIIB型筋線維に分類し（Brooke and Kaiser, 1970），筋線維型構成の算出を行った．またソックスレイ法によりそれぞれの骨格筋内の脂肪含量割合を測定した．黒毛和牛骨格筋の筋線維型構成に関して，骨格筋の種類により割合が異なった．すなわちI型筋線維を多く持つ胸腹鋸筋（61.7％），胸最長筋（45.8％），大腿二頭筋上部（52％），中程度持つ外側広筋（30.0％），大腿二頭筋下部（32.6％），およびI型筋線維がさらに少ない半腱様筋（24.6％），半膜様筋（26.4％），大腿直筋（23.3％）に分類された．一方，II型筋線維はI型筋線維と逆の傾向を示しその傾向はIIA型筋線維の変化というよりはIB型筋線維の変化として現れた．各骨格筋内の脂肪含量割合も骨格筋間で著しい差異が認められた．胸腹鋸筋は57.4％と最も大きく，以下胸最長筋27.9％，大腿二頭筋上部22.8％，大腿直筋15.7％，大腿二頭筋下部13.5％，外側広筋12.2％，半膜様筋10.6％，および半腱様筋10.4％の順で減少した．筋線維型構成割合と骨格筋内脂肪含量割合の相関関係を見ると，I型筋線維の割合とは正の，逆にIIA型およびIIB型筋線維の割合とは負の有意な相関関係が認められた．本研究より黒毛和牛去勢肥育牛において，骨格筋の種類により骨格筋内に蓄積される脂肪含量割合は著しく異なり，それは筋線維型構成と密接に関係していることが明らかになった．The interrelationship between myofiber type composition and intramuscular-fat content was investigated in muscles of Japanese Black cattle. The cattle were mainly fed with concentrate and slaughtered at 26-29 mo of age. After slaughter, M.longissimus thracis, M.biceps femoris, M.semimembranosus, M.semitendinosus, M. vastus lateralis, M.serratus ventralis and M.rectus femoris were removed from each carcass. Myofibers were enzyme-histochemically classified into type I, IIA and IIB myofibers according to the nomenclature of Brooke and Kaiser(1970). The percentage of intramuscular-fat content in each muscle was measured with Soxhlet method. In these muscles, the percentage of each type myofiber was related significantly to the percentage of intramuscular-fat content of each muscle at 26-29 mo of age. Correlation coefficient between the percentage of Type I myofiber and intramuscular-fat content was positive significant (p<0.005). Conversely, correlation coefficient between the percentages of type IIA, IIB myofiber and intramuscular-fat content was negative significant (p<0.05). These results indicated that the percentage of Type I myofiber was significantly related to the accumulation of intramuscular-fat in the muscles of Japanese Black cattle