Reliability of a New Application for Smartphones (DrGoniometer) for Elbow Angle Measurement

Abstract

Joint goniometry is a common mode of clinical assessment used in many disciplines, in particular rehabilitation [1][2][3]. One way to perform joint goniometry is through the use of computer-aided joint measurements from digital photographs [4][5][6][7][8]. This method entails a complex procedure to obtain the range of motion (ROM) value, which consists of the picture being manipulated upon by dedicated software once it has been downloaded from the camera to a computer.Recently, a new iPhone (Apple Inc, Cupertino, CA)-based application (app) functioning as a virtual goniometer, DrGoniometer (DrG; C.D.M. srl, Milano, Italy), has been developed to provide a simpler, faster measurement of limb joint mobility ( Figure 1). Measurements with the DrG app are obtained by positioning a virtual goniometer, visible on the smartphone screen, on a picture previously taken by the mobile camera. The software creates an easily retrievable patient database. After selecting the patient, the clinician chooses the desired joint from a list and the respective motion to measure (eg, flexion, extension), then simply takes a photo of the limb, saves it, measures the joint angle, and observes the value. For research purposes, it is possible to blind the rater to the angular value. Notes can be added to each picture. The measurements and pictures are stored in the smartphone database for further analysis, if required. All data can be easily downloaded to a computer to obtain direct written reports.We assessed the reliability (intra-and interrater correlation and agreements analysis) of DrG in comparison with a small plastic universal goniometer (UG) [1] for elbow ROM measurement [9]. Twenty-eight pictures of elbows of healthy subjects, measured by UG at different angles, were assessed with DrG by 7 raters, selected as expert clinicians and working in 2 different facilities. Measurements were repeated after 1 week. Each picture was judged adequate, that is, without evident perspective error. Raters were blinded to all joint angles values. The 392 measurements were used to assess: the intraclass correlation coefficient (ICC) for intrarater and interrater reliability [9]; and the agreement between the DrG and UG, considering 10°as the acceptable interval (width) within which 95% of differences between measurements by the DrG and UG are expected to lie (limits of agreement, LoA ϭ -5°, ϩ5°) [10,11].The results showed high intra-and interrater correlation (ICC ϭ 0.998, 95% confidence interval 0.998-0.999, and ICC ϭ 0.998, 95% confidence interval 0.996-0.999, respectively). The width of 95% LoA between DrG and UG was equal to 10.26°( LoA ϭ ϩ4.51°, Ϫ5.75°).In a 1985 report, Fish and Wingate [2] assessed the accuracy of elbow goniometry by comparing a manual goniometer with (conventional) photographic measurements. They found that the accuracy of elbow angle measurement via photography was greater than via the standard goniometer. The authors explained the difference by stating that the precision of the photographic method was dependent on the use ...

Goniometer-apps in hand surgery and their applicability in daily clinical practice

“…al were investigating the iOS photogoniometer "DrGoniometer" in 2011 and 2013. In the former, the app was compared to a standard mechanical goniometer and judged reliable [11]. In the latter, the authors assessed in the same methodical setting angles in a knee joint, drawing the same conclusions [12].…”

Intra- and inter-examiner reliability in angular measurements of the knee with a smartphone application

“…Good to excellent reliability has also been found for the measurement of the range of motion of other joints with the use of smartphone applications [10][11][12][13][14][15][16]. While studies have demonstrated that smartphone applications are reliable for use in research and clinical practice [3,6,[9][10][11][12][13][14][15][16], there is a wide diversity of goniometric applications to be tested. According to Milani et al [1], further studies are needed for the validation of these applications for different joints and conditions.…”

The uses of smartphones and tablet devices in surgery: A systematic review of the literature

“…31,32 Ten orthopedic studies evaluated smartphone apps designed to measure joint angles and range of movement, either in real-time on live patients or from photographs or radiographic images of joints; these studies compared these novel methods with other well-established ''gold-standard'' techniques (see Table I). [20][21][22][23][24][25][26][27][28][29] Spinal, 24-26 shoulder, 27 elbow, 28 knee, [20][21][22][23] and metatarsophalangeal 29 joint angles were measured by apps using either the in-built smartphone accelerometer or a virtual in-app goniometer.…”