Reliability of a smartphone-based goniometer for knee joint goniometry

Abstract

The aim of this study was to assess the reliability of a smartphone-based application developed for photographic-based goniometry, DrGoniometer (DrG), by comparing its measurement of the knee joint angle with that made by a universal goniometer (UG). Joint goniometry is a common mode of clinical assessment used in many disciplines, in particular in rehabilitation. One validated method is photographic-based goniometry, but the procedure is usually complex: the image has to be downloaded from the camera to a computer and then edited using dedicated software. This disadvantage may be overcome by the new generation of mobile phones (smartphones) that have computer-like functionality and an integrated digital camera. This validation study was carried out under two different controlled conditions: (i) with the participant to measure in a fixed position and (ii) with a battery of pictures to assess. In the first part, four raters performed repeated measurements with DrG and UG at different knee joint angles. Then, 10 other raters measured the knee at different flexion angles ranging 20-145° on a battery of 35 pictures taken in a clinical setting. The results showed that inter-rater and intra-rater correlations were always more than 0.958. Agreement with the UG showed a width of 18.2° [95% limits of agreement (LoA)=-7.5/+10.7°] and 14.1° (LoA=-6.6/+7.5°). In conclusion, DrG seems to be a reliable method for measuring knee joint angle. This mHealth application can be an alternative/additional method of goniometry, easier to use than other photographic-based goniometric assessments. Further studies are required to assess its reliability for the measurement of other joints.

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

“…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]. Both studies assessed intra-rater and inter-rater variability.…”

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.…”

Inclinométrie du genou : comparaison de la reproductibilité d’un outil mécanique et d’une application sur smartphone

“…Ainsi, lors de la flexion du genou, pour l'inclinomètre manuel, la reproductibilité intraévaluateur est proche de 0,88 alors que la reproductibilité inter-évaluateurs oscille entre 0,74 et 0,81 [17], ce qui est nettement inférieur aux valeurs d'ICC calculée pour le rachis [11]. Une étude récente utilisant une application téléphonique basée sur une goniométrie à partir d'une photo pour la mesure des amplitudes du genou obtient des valeurs de reproductibilité supérieures à 0,90 [18]. Cependant, cette méthode reste complexe (multiplication des étapes) et est directement dépendante de l'accord du patient pour la prise de vue.…”