Sports Medicine Research: In the Lab & In the Field: Measuring Lower Extremity Kinematics? Yep, They Have an App For That (Sports Med Res)
Monday, November 10, 2014

Measuring Lower Extremity Kinematics? Yep, They Have an App For That

Reliability of Using a Handheld Tablet and Application to Measure Lower Extremity Alignment Angles

King D.L, Belyea B.C. J Sport Rehabil; 2014; ahead of print

Take Home Message: A tablet application is a promising, reliable tool to capture objective landing kinematics. Intra-rater reliability is good to excellent with an average of 6 trials. Inter-rater reliability is fair to excellent depending on the level of experience.

Evaluating an athlete’s risk for injury is necessary to tailor injury prevention plans for an athlete. To assess risk for injury, medical personnel most commonly employ visual observations of an exercise (e.g., drop vertical jump); however, errors in visual estimations of lower extremity joint angles have been reported. Utilizing a tablet with a movement analysis application is a more objective way of determine joint angles during functional movement. Though, the reliability of this new tool has not been established. Therefore, the authors measured the inter-rater and inter-trial reliability among multiple researchers who evaluated 23 healthy college students using an iPad2 and the KinesioCapture application. The athletes performed 6 two-footed drop vertical jumps, while 1 researcher with experience with 2-D videography captured all the trials. Then, 4 researchers (2 experienced & 2 novices) analyzed the previously captured video for the degrees of knee and hip flexion. The researchers measured 3 of the jumps in the sagittal plane followed by 3 jumps in the frontal plane. Inter-rater reliability ranged from low (0.39) to excellent (0.98). Experienced raters performed slightly better with moderate to good reliability (0.69-0.93) compared with the novice raters (0.39-0.98). Novice and experienced raters were more consistent at measuring joint angles at maximum knee flexion than at initial ground contact. Averaging the trials offered better reliability than assessing each trial separately.

This is an important study since properly operating new and affordable tools are imperative for better objective measures to determine an athlete’s risk of injury. The authors demonstrated that the handheld tablet is a reliable tool to measure knee and hip flexion during a drop vertical jump. The authors also found that experience as well as multiple trials are necessary for optimal reliability. An average of multiple trials may represent the true movement pattern, and reduces the influence of errors (e.g., a bad movement on one trial, error in one measurement). Future research needs to determine how much training medical personnel requires before becoming an experienced rater. Furthermore, all of the videos were captured by a trained individual so we may need to train clinicians to capture an optimal video for these analyses. Future research, will have to determine how much measurement error could be caused by changes in how the videos are acquired. Additionally, assessing how many trials are required for a reliable reading is necessary to apply this tool for functional use. It will also be interesting to see how these measurements compare to traditional motion analysis systems. While more research is needed this study shows that measuring lower extremity movement can be reliably assessed on a tablet if one experienced person records the video, average joint angles are calculated across three trials, and the person doing the measurement is adequately trained. This study is a good reminder that clinicians should check their reliability over time and among other clinicians in a clinic to ensure consistency.

Questions for Discussion: Do you have access to a tablet? If so, would you use the tablet to measure landing kinematics? Do you measure/observe landing kinematics to identify athletes at risk for knee injuries?

Written by: Jane McDevitt, PhD
Reviewed by: Jeffrey Driban

Related Posts:

King DL, & Belyea BC (2014). Reliability of Using a Handheld Tablet and Application to Measure Lower Extremity Alignment Angles. Journal of Sort Rehabilitation PMID: 25310432


Rachel Koldenhoven said...

Yes, I have access to a tablet although it is not an iPad. As someone who is interested in research, I think that I would definitely like to try using the tablet to do some 2D motion capture. I would also like to see the inter-rater reliability for values in the frontal plane, but realize that there are probably limitations with the traditional landmark placements.

I feel that the use of 2D videography for measuring joint angles will become more common with athletic trainers. It is a useful tool for us that is both functional and cheap. Using 3D motion capture is great, but it takes time, clinician experience, and the systems are costly. 2D motion analysis is a great tool for athletic trainers who are not fortunate enough to have access to 3D analysis.

Andrea Baellow said...

I would definitely use this in the clinic to measure landing kinematics if I knew specifically what degrees and angles were putting athletes at risk. Since landing in varus is rare, I would need to know what to look for when I find a valgus collapse. I think an interesting part that may be missing from this is comparison to 3D kinematics and the reliability between the two.

Kyle Murray said...

I think that utilizing technology in this way will provide clinicians with valuable tools and information that can improve the way we identify injury risk and movement patterns. I agree that it would require training for the clinicians but by increasing the number of trained professionals, it could increase the prevalence of use throughout the healthcare professions. I also think that 2D imaging and motion analysis is tricky and standardized procedures must be provided in order to determine the distance, height, angles, and frame rate of the cameras if being used for measure joint kinematics. I think if we were able to standardized these variables and train the necessary readers then this tool would prove to be very effective. In the smart phone and technological age we are in now, this would also stimulate a lot of interest among the younger healthcare professionals.

Jane McDevitt said...

Great points, I agree I think athletic trainers will be using this type of technology more and more as it becomes more readily available. I believe Kyle brings up a great point, that these protocols will need to be specific for each athlete (sex, height, weight, q-angle, so many variables to consider), so I think there is still more room to grow before this type of technology will be consistently used in the athletic training room.

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