A study on the distribution of the footsole pressure with standing on one leg Masabumi Miyamoto Department of Orthopedics (Director : Prof. Yasumasa S

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1 A study on the distribution of the footsole pressure with standing on one leg Masabumi Miyamoto Department of Orthopedics (Director : Prof. Yasumasa Shirai), Nippon Medical School Much has been reported about the quantitative analysis of the footsole pressure in normal persons, but no definite conclusions have been obtained from these studies. This is also particularly true in the study of deformed feet. In order to analyse the extent and degree of deformities, distribution maps of footsole pressure were made to compare normal and deformed feet. One hundred feet in 50 normal persons and 172 feet in 96 patients with RA with flat foot, hallux valgus or spread foot deformity were tested. Footsole pressure maps were made from the high sensitive film "Prescale", made by Fuji film. Each person was asked to stand on one leg on the film for 5 seconds. Bony anatomical observations of the foot were done with two views of X-ray film. In this study, distribution maps and the X-ray film were analyzed only in the forefoot. Results : 1) In normal persons, the highest pressure was observed in the Ist metatarsal head, 1.74% per cm2 of the body weight, and the mean value of II, III, N and V metatarsal head decreased in order. 2) The medial longitudinal arch was higher in cases with a higher value in I metatarsal head than in the others. 3) Footsole pressure in RA showed an increasing weight bearing area on the V metatarsal head and V tarso-metatarsal joint. 4) In cases of flat feet, when C/OY, N/OY and L/OY had a lower value than 0.25, 0.22 and 0.17 respectively, the weight bearing area showed up on I TMT joint initially, and with progress of deformity, pressure increased on the area. 5) In hallux valgus, pressure was higher on the III MTH with an increasing degree of deformity. 6) There were no changes of the footsole pressure maps in spread foot deformity compared with a normal foot. Key words : prescale film, rheumatoid arthritis, footsole pressure, quantitative analysis, foot deformity Present address : Department of Orthopedics, Nippon Medical School, 1-1-5,,Sendagi, Bunkyo-ku, Tokyo, 113 Japan

2 (357)43 フィルムプレスケールを用いることにより,簡便で容易な操作により足底面圧の定量的解析を行い, さらにX線計測値から足部の骨格構造を評価し,その (2)方法各対象足は足底面圧計測のためのFoot Printを両者の結果を対比させることにより新たな観点から正ける足底面圧を計測した.また足部変形の評価は,X 常者の立位足底面圧分布について検討を加えた.また, 線像を下記の方法にて計測して行った. 正常足との比較検討において代表的な足部変形である扁平足,外反母趾,開張足等の足底面圧分布を計測し, 採取し,足部X線像と照合し,足底各部の単位面積にお 1)Foot Printの採取足底面圧を計測する手段として富士フイルム社製超それぞれの変形の過程が足底面圧に及ぼす影響につい低圧用感圧フィルムプレスケールて検討した, この感圧フィルムの測定域は5 25kg/cm2でを使用した. あり, 直接足底面圧を測定するのは困難であるので,増感度研究対象および方法 (1)対装置10)として高さ2.2mm,底象起4134個正常例として,足部の疼痛および変形のない健康人を選び,18 58歳の成人男女50名,100足を正常辺5mm径の円錐状突を片面にしきつめた合成ゴムマットを使用した.これにより測定域は0.1 10kg/cm2となり足底面圧の計測が可能となった. Foot Printの採取はゴムマットの突起面とアクリル足とした. 異常例として,日本医科大学付属病院整形外科および関連病院にて治療中の年齢29 89歳におよぶ96 板の間に感圧フィルムを置き,マットの上に片足をのせて5秒間片脚起立位を保持させる方法をとった.足をリウマチ足とした.リウ底面圧測定時に剪力を働かせないように可及的正確にマチ足は変形,異常を呈する確率が高いので,本研究垂直方向の力のみをかける必要があり,片脚起立時の名のリウマチ患者の172足では変形足の代表としてリウマチ足を選んだ.まその変形は種々あるが,そた, の中で今回は扁平足,外反母趾および開張足変形のみについての検討を行った. Fig. 1 New designed supporting ぐらつきを予防し足底面圧分布の再現性を確保する目的でFig.1に示す支持器を考案した.採取に先立ち被験者に十分説明し練習してから施行した. device to minimize the body shifts

3 44(358) 2)X線撮影 angle)を正面像は西野式下肢像消去法に準じて撮影した. この方法は足関節底屈位と背屈位を同一フィルムに重 4)足それぞれ求めた(Fig.2). 底面圧の計測 Foot printと正面X線像を照合し,第1 5中複撮影することにより,下腿像を消去し足の全骨格の骨骨頭部(1MTH 5MTH),第1足背底像を写し出すことができる部(1TMTJ),第5足側面像は足長軸に直交し焦点を舟状骨にあわせてフロアーと平行な角度より撮影した. 3)X線 (i)正 Markを像の計測 Pkgを面X線像の値を除し,足底1cm2に第1足指基節骨,第1,第2および第5中足骨にそれぞれ中線を引き骨軸となし,第1足 %値根中足骨関節根中足骨関節部(5TMTJ)および踵骨隆起部(Heel)の7カ Calibration 足所についてFoot 用いて1cm2に計測した(Fig.3).さ Load おける荷重らに体重Wkgでそ及ぼす体重の割合P/Wをとして計算した. 指基節骨骨軸と 5)足部変形の評価足骨骨軸と第2 X線計測値より扁平足,外反母趾,開張足の変形の中足骨骨軸のなす角度および第1中足骨骨軸と第5中有無を検討した.判定基準は扁平足については横倉法足骨骨軸とのなす角度をそれぞれ求めた. に準じてC/OYが0.30以第1中足骨骨軸とのなす角度,第1中 (ii)側面X線像横倉法下のものとした.外反母趾は第1足指基節骨骨軸と第に準じて,踵骨隆起の最下点をo点,第 1中足骨種子骨最下点をy点,距点をc点,第1楔骨舟状骨関節の中央状骨舟状骨関節の中央点をn点, 第1中足骨楔状骨関節の中央点を1点からc,n,1点下かっN/OYが0.26以度が30 より大きいものとした. とした.直線oy までの距離をC,N,Lとし,直線oy の長さOYで除した値C/OY,N/OY,L/OYの求めた.o点より踵骨底面の接線をひき,それとoy とのなす角度(calcanealpitch)と,o点 1中足骨骨軸のなす角度が20 より大きいものとし, 開張足は第1中足骨骨軸と第5中足骨骨軸のなす角値をよりひいた踵骨底面の接線と第1中足骨骨軸とのなす角度(hibbus Fig. 2 Anatomical bony landmarks Fig. 3 Superimposing foot print over a X-ray film

4 Table 1 Mean value and its standard deviation of P/W in each region of footsole in normal feet (359)45 (n=100) Table 2 Mean value and its standard in Type 1 and 2 deviation of P/W in each region of footsole (Type 1 n=38, Type 2 n=24) Fig. 4 The footsole pressure in normal person In Type 1, load pressure shifted toward the 1st metatarsal head in the fore foot, and Type 2, the 2nd and 3rd metatarsal heads. Table 3 C/OY, N/OY, M.I.P.I. angles and Int. m. 1-5 angles of normal persons (n=100)

5 46(360) Table 4 Mean value and its standard deviation of P/W in each region of footsole in 172 deformed feet in rheumatoid arthritis (n=172) Fig. 5 Classification of deformed arthritis feet in rheumatoid Table 5 Obtained values in the flat foot, hallux valgus, and spread foot group

6 Fig. 6 P/W value in rheumatoid foot and normal foot There were significant difference statisticaly between P/W in the 1st TMT joint, the 5th metatarsal head and the 5th TMT joint. Fig. 7 P/W value in flat foot and normal foot There were significant difference statistically between P/W value in the 1st TMT joint and the 5th TMT joint. Fig. 8 The correlation between P/W values of the 1st TMT joint and C/OY

7 48(362) Fig. 9 The correlation between P/W values of the 1st TMT joint and N/OY Fig. 11 P/W value in the hallux valgus and normal foot There were significant difference statistically between P/W value in the 3rd metatarsal head, the 5th metatarsal head and the 5th TMT joint. Fig. 10 The correlation between P/W values of the 1st TMT joint and L/OY Fig. 12 The correlation between P/W values in the 3rd metatarsal head and metatarsal 1-phalangeal 1 angle

8 (363)49 Fig. 13 P/W value in the spread foot group and normal foot There were significant difference between P/W value in the 3rd metatarsal head, the 5th metatarsal head, the 5th MTM joint and calcaneal tuberosity.

10 11) Nishino, H.: Structural studies of the foot bones by dorsoplantar roentgenograms and frontal tomography. J. Jap. Orth. Surg. Society, 32, 1117 `1135, ) Elftman, H.O. : A cinematic study of the distribution of pressure in the human foot. Anat. Rec.,59, 481 `490, ) Morton, D.J.: Foot biomechanics, functional disorders and deformities. "Medical physics" (Glasser, O. ed.), p. 457 `466, Year Book Publishers, Chicago, ) Jones, F.W. : Structure and function as seen in the foot. Bailliire, Tindall & Cox, London, ) Burger, E.S.: The measurement of the static forces at the weight bearing points of the feet with reference to critical heel heights and 'split heel' factors. Chiropody Record, 35, 1 `17, ) Aritomi, H. : Measurement of the footsole pressure distribution of normal subjects by pressure sensitive films. J. Jap. Orth. Surg. Society, 57, 341 ` 349, ) Collis, W.J.M.F. and Jayson, MIN. : Measurement of pedal pressure. Ann. Rheum. Dis., 31, 215 `217, ) Dickson, F.D. and Divelly, R.L.: Functional Disorders of the Foot. 3rd ed., Lippin cott, Philadelphia, 1953.

420 pressure under the metatarsal head was calculated and compared to that of the normal subject. In rheumatoid arthritic patients, the peak of the pr

420 pressure under the metatarsal head was calculated and compared to that of the normal subject. In rheumatoid arthritic patients, the peak of the pr Pressure Distribution Measurement under the Foot on Walking in Rheumatoid Arthritis Junichi MONJ I et al. Department of Orthopedic Sargery, School of Medicine, Hokkaido University Abstract Foot pressure