Original researchThe TiltMeter app is a novel and accurate measurement tool for the weight bearing lunge test
Introduction
The measurement of ankle joint dorsiflexion is routinely performed by clinicians treating lower limb pathologies to specifically evaluate the cause and effect that reduced ankle motion can have on normal gait1 and injury.1, 2 The accurate measurement for available ankle range of motion has been demonstrated to be critical due to the decision-making and subsequent therapy implemented by health practitioners who manage lower limb musculoskeletal pathology.3
In order to accomplish accurate quantification of joint motion and stiffness, a variety of measurement techniques have been reported in the literature. These techniques have had variable results due to both equipment, clinician technique and the challenges of soft tissue variability.4 Past research has established baseline measurements in a non-weight bearing5 or weight bearing position,6 with the measured leg bent at the knee6 or the leg straight,3, 7 with or without instrumentation.8 Recent investigations has found that weight bearing ankle joint range of motion measurements show higher intra and inter reliability than non-weight bearing measures9 and a valid measure of gastrocnemius and soleus length.10
The weight bearing lunge with the leg bent at the knee has demonstrated excellent inter-rater and intra-rater reliability (ICC 0.97–0.98)6 and the same test performed together with the leg straight has been used with similar reliability results.7, 11 These measures have been reported in range of motion studies with either a standard angle finder (inclinometer)7 which has small gravity fed instrumentation or a digital inclinometer placed either at the anterior of the tibia or at posterior flat surface of the Achilles tendon.3, 6, 11 The introduction of the digital inclinometer was aimed to increase the size of the displayed measurement to allow ease and accuracy in reading the result by the clinician. However this instrumentation is often costly, with a single measurement tool in excess of $150(AU).
With the advent of smart phone technology, apps are being introduced into every day practice in the clinical setting. One recent study found the majority of health care providers own a smartphone, with over half of those surveyed, regularly use an app within clinical practice with patients.12 Smartphone apps offer a cheap and widely accessible means for measurement in a range of areas. More recently the use of smart phones have been tested for reliability of measure in spinal motion13 and knee measures.14, 15 It is important to establish the reliability and validity of these apps at each joint if this measurement approach is to be compared with other criterion standard approaches to ensure the usage is appropriate.
This study aims to compare the intra-rater and inter-rater reliability and, concurrent validity of the Tiltmeter app on a smartphone compared to a digital inclinometer. Thus determining if this technology is appropriate to use when measuring ankle range of motion.
Section snippets
Methods
The study design was implemented to test the following:
- 1.
Intra-rater and inter-rater reliability of the weight bearing lunge test with leg straight and knee bent using the digital inclinometer
- 2.
Intra-rater and inter-rater reliability of the weight bearing lunge test with leg straight and knee bent using the Tiltmeter app on the iPhone
- 3.
Concurrent validity between the digital inclinometer and the TiltMeter app on the iPhone
Allied health clinicians were recruited within the workplace setting to
Results
A total of 20 people were recruited to the study. There was a majority of females (16 female), with a mean (SD) age of 40 (±12) years with a mean (SD) body mass index (kg/m2) of 25.4 kg/m2 ± 5.0 kg/m2. All participants gave written consent and disclosed no history of recent foot or ankle injuries or surgery at the right foot. No participants had a history of a neuromuscular condition.
The ICC between the instrumentation on static hard surfaces was 0.9973 and the 95% limits of agreement −4.064 to
Discussion
The aim of this study was to explore if the use of a low cost and easily accessed app on a smartphone, was appropriate to be used within the clinical setting. The results determined all scores excepting one to be above 0.8, well beyond the acceptable level of correlation.19 Previous studies have determined that the use of the weight bearing lunge, with varied measurement instrumentation and position of instrumentation have high reliability (0.85–0.96).6, 11, 20 This study has also determined
Conclusion
The use of the TiltMeter app on the iPhone is a reliable measure of ankle range of motion in healthy adults. Clinicians should use clinical judgement and caution in when using this technology on different smart phone technology to that mentioned within this study.
Practical implications
- 1.
Clinicians can confidently utilise smartphone technology within clinical practice for monitoring ankle joint range of movements
- 2.
Researchers can incorporate the use of a low cost measurement tool/technology into study designs
- 3.
Further investigations into the reliability of different smartphone technology can be conducted to improve clinical outcomes
Acknowledgements
No financial support was obtained for this study.
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