Using a smartphone as a tool to measure compensatory and anomalous head positions

ABSTRACT Purpose: To describe a new method for measuring anomalous head positions by using a cell phone. Methods: The photo rotation feature of the iPhone® PHOTOS application was used. With the patient seated on a chair, a horizontal stripe was fixed on the wall in the background and a sagittal stripe was fixed on the seat. Photographs were obtained in the following views: front view (photographs A and B; with the head tilted over one shoulder) and upper axial view (photographs C and D; viewing the forehead and nose) (A and C are without camera rotation, and B and D are with camera rotation). A blank sheet of paper with two straight lines making a 32-degree angle was also photographed. Thirty examiners were instructed to measure the rotation required to align the reference points with the orthogonal axes. In order to set benchmarks to be compared with the measurements obtained by the examiners, blue lines were digitally added to the front and upper view photographs. Results: In the photograph of the sheet of paper (p=0.380 and a=5%), the observed values did not differ statistically from the known value of 32 degrees. Mean measurements were as follows: front view photograph A, 22.8 ± 2.77; front view B, 21.4 ± 1.61; upper view C, 19.6 ± 2.36; and upper view D, 20.1 ± 2.33 degrees. The mean difference in measurements for the front view photograph A was -1.88 (95% CI -2.88 to -0.88), front view B was -0.37 (95% CI -0.97 to 0.17), upper view C was 1.43 (95% CI 0.55 to 2.24), and upper view D was 1.87 (95% CI 1.02 to 2.77). Conclusion: The method used in this study for measuring anomalous head position is reproducible, with maximum variations for AHPs of 2.88 degrees around the X-axis and 2.77 degrees around the Y-axis.摘要： 研究目的：描述一种利用手机测量异常头位（anomalous head position）的全新方法。 研究方法：本研究借助iPhone®的照片（PHOTOS）应用的图片旋转功能开展实验。患者端坐于座椅上，于背景墙面固定一条水平标线，于座椅上固定一条矢状位标线。按以下视角拍摄照片：正面视图（照片A、B，头部向单侧肩部倾斜）及轴位上方视图（照片C、D，拍摄额头与鼻部），其中A、C未发生相机旋转，B、D存在相机旋转。同时拍摄一张印有两条夹角为32°直线的白纸照片。招募30名检查者，要求其调整旋转角度，使参考标线与正交坐标轴对齐后完成角度测量。为设置用于与检查者测量结果对比的基准值，研究人员通过数字手段在正面视图与轴位上方视图的照片中添加蓝色标线。 研究结果：在白纸照片的测量中（p=0.380，检验水准α=5%），实测值与已知的32°夹角无统计学差异。各组平均测量结果如下：正面视图A为22.8±2.77，正面视图B为21.4±1.61，轴位上方视图C为19.6±2.36，轴位上方视图D为20.1±2.33（单位：度）。正面视图A的测量平均偏差为-1.88（95%置信区间95% CI：-2.88~-0.88），正面视图B为-0.37（95% CI：-0.97~0.17），轴位上方视图C为1.43（95% CI：0.55~2.24），轴位上方视图D为1.87（95% CI：1.02~2.77）（单位：度）。 研究结论：本研究所采用的异常头位测量方法具备良好的可重复性，X轴方向异常头位的最大偏差为2.88°，Y轴方向为2.77°。