入院高齢者の転倒予防因子に関する研究—下肢筋力および骨量の追跡調査を通して

Preventive Factors of Falls in the Institutionalized Elderly: Muscle Strength in the Lower Extremities and Ultrasound Bone Densitometry

　入院高齢者の転倒・骨折要因である下肢筋力，骨量，転倒の実態および2年間の推移を性別，年齢別，移動・移乗能力別に明らかにした．対象は65歳以上の入院・入所高齢者であり，初年度は118名，次年度は138名であった．測定方法は，下肢筋力は徒手保持型マスキュレーターを使用し，骨量は骨梁面積率を算出する超音波測定装置Steosgraph Mark-6000を用いた．その結果，転倒は30％の発生率であり，筋力では年代が上がるごとに，また移動能力が低下するごとに下肢筋力が低下した．骨量では，どの分類に限らず骨粗鬆症の危険域である25％以下であった．追跡できた対象の移動能力下降群の筋力は6.4kgから4.7kgへと低下し，うち53％が転倒者であった．以上のことから，入院高齢者の下肢筋力，骨量は低下しており，また，高齢者の下肢筋力と移動能力および転倒発生に何らかの関係があると示唆された．

　Objective : To identify muscle strength in the lower extremities and ultrasound bone densitometry in institutionalized elderly individuals by analyzing their history of falls as well as their sex, age, and transfer ability.

　Methods : Isometric maximal knee-extension strength was measured by a hand-held dynamometer and ultrasound bone densitometry by Steosgraph Mark-6000. T-test and chi-square test were performed and analyzed.

　Subjects : One hundred and eighteen elderly individuals in 1997 and 138 in 1998 were examined, and 64 elderly individuals(mean age 83.1 ± 6.8)were followed up for two years in two geriatric institutions.

　Results : About 30% experienced more than one fall per year. As age increased and transfer and gait ability decreased, the muscle strength and ultrasound bone densitometry significantly decreased (p＜0.05, p＜0.01, p＜0.001). Regardless of sex, age, and transfer ability, the results of all ultrasound bone densitometry tests were under 25%, indicating osteoporosis. The muscle strength of twenty percent of elderly persons with decreased transfer ability tended to decrease from 6.4 kg to 4.7 kg, and 53 % of these experienced falls.

　Conclusion : The institutionalized elderly showed a remarkable decline in muscle strength and ultrasound bone densitometry because of multiple diseases and limited physical activities resulting from aging, limited moving place, and so on. Also, the results obtained suggested the relationship between proclivity to falling and declined muscle strength and transfer ability.