扁平足因為足弓的避震效果較差，耐力不足，想要從事長時間的站立、行走、長跑、登山等運動，有其潛在的困難和危險。有鑑於因此，內政部於2007年將「扁平足」的規定修訂為站立照（X光攝影）足之正側位（true lateral view）足弓角度大於168度。然而，X光是較費時耗資的判定方法，是否有更便利的方法可以判定扁平足？本研究以1,290名役齡男子為研究對象，量測方法分別採用X光攝影、踩足印及足底掃描（Ming Scan），經放射科醫師、骨科醫師專業判定及研究人員進行軟體分析計算，將所得資料以SPSS17.0軟體計算足弓角度（arch angle,AA）、足印的足弓指標（arch index, AI）與足底掃描所得的足弓指標三者的相關性，顯著水準α = .05。結果顯示，在1,290名役齡男子中，任一足足弓角度大於168度者有9位，比率為0.7%。X光足弓角度與足印的AI的相關係數為0.556，達顯著正相關，且足印之足弓指標一定要大於0.33才有可能大於168度； X光足弓角度與足底掃描測量的AI的相關係數為0.412，達顯著正相關；足印的AI和Ming Scan量測的AI相關性最高達0.794，顯見足印和Ming Scan量測的數值結果相當接近。根據以上結果，若要用其它指標代替足弓角度，足印的足弓指標是較好的選擇，本研究結果亦可供日後判定扁平足時參考。

Because of the lower anti-vibration effect, it is difficult and dangerous for those people with flatfeet to standing, walking, running, climbing for long period. Thus, the Ministry of the Interior Taiwan R.O.C. gives a clear definition of flatfoot: the lateral view arch angle with X-ray is more than 168o. However, to determinate flatfoot by taking X-ray picture is an expensive method. And it will take more time to make sure if it is flatfoot or not as well. Is there any more effective and inexpensive method? We recruit 1,290 draftees and take their footprint by X-ray, printed, plantar capture to compare arch angle (AA), arch index (AI) by taking footprint and AI by plantar capture. The results indicated that: (1) there were 9 persons whose arch angle was more than 168o and the prevalence was about 0.7% in those 1,290 draftees. (2) The correlation was 0.556 between AA and AI by taking footprint. Only the value of AI was more than 0.33 then the AA will be larger than 168o. (3) The correlation was 0.412 between AA and AI by Ming Scan. The correlation was 0.794 between AI by taking footprint and AI by Ming Scan. According to the results that mentioned above we considered that AI by taking footprint was similar to AI by Ming Scan. According to the results, if we want to substitute for AA, AI by taking footprint was better choice. They also provided references for determining flatfoot.