Goniometer

There are 2 goniometer apps I have been played around with that I feel I might use from time to time in the clinic or out and about.

1) Goniometer Pro

This app utilizes the accelerometers in the phone to measure angles and acts essentially as an inclinometer.  The downside to this is that some phones are long and do not have a nice small base you can put against a patient.  I have seen somewhere, but currently cannot find it, some sort of phone case that has a base like a bubble inclinometer.  I am curious if just simply creating a makeshift base to attach to your phone case would be effective and should not matter when you zero out the application to measure.  The phone can either be used to measure on its side or on its back to help get better measurements for certain joints.  It's also great for leveling pictures or making sure a surface is precisely parallel to the ground.

This application gives you an arc of motion when measuring and may be difficult to get the correct measurement if you cannot start at the appropriate beginning point for measuring a motion such as hip flexion (i.e. the patient can be in slight hip flexion/extension and give you more/less than what is considered normal values).

This article by Tousignant-Laflamme et al. (2013) looks at the reliability and criteriorn validity of an accelerometer application and the use of the iPhone's magnetometer to measure cervical ROM in healthy patients and compared it to the use of a CROM.  The accelerometer app was used to measure cervical flexion, extension, and lateral flexion whereas the magnetometer was used to measure rotation.  All positions were seated.
Results

• Moderate intra-rater reliability for each movement (ICC = 0.65-0.85)
• Poor inter-rater reliability (ICC < 0.60)
• Criterion Validity moderate (ICC > 0.50) to good (ICC > 0.65) for movements of flexion, extension, lateral flexion and right rotation but poor (ICC < 0.50) for left rotation.

I am curious to why this study chose to use the magnetometer.  I imagine they would have had better results if the measured the subjects cervical rotation in supine using the accelerometer as currently phones do not measure rotation well when the phone's z axis is in line with gravity (hence why the magnetometer was used).  I would love to be apart of a team to standardize test positions for the use of phones to collect objective data.  Even though there is poor inter-rater reliability, the good intra-rater reliability should be acceptable as long as you keep your measurements consistent and are the only one who sees your patient.

Another article by Ockendon et al. (2012) looked at measuring slight knee flexion in healthy subjects with the use of an accelerometer compared to a telescoping goniometer.
Results

• Telescoping goniometer
• Intraobserver reliability ±9.6° (r=0.927)
• Interobserver reliability ±8.4° (r=0.952)
• iPhone
• Intraobserver reliability ±4.6° (r=0.982)
• Interobserver reliability ±2.7° (r=0.994)
• Both Instruments Correlation r=0.947 and have a mean difference of -0.4° (SD 3.86°)

This study shows using the iPhone's accelerometer as a goniometer can be reliable for measuring subtle knee flexion in patients with certain conditions such as an ACL repair.

2) DrGoniometer

This app you use your camera to snap a picture of your client and align the points to get a measurement (forgive me if my land marks are not spot on as I did this very quickly to get a screenshot of its use).  One thing I enjoy about this app is it shows the line of gravity while you are talking the photo to get your camera straight up and down.

This article by Ferriero et al. (2011) examines the reliability of this particular app in elbow ROM in healthy patients in comparison to a universal goniometer.
Results

• Intra-rater correlation (ICC = 0.998, 95% CI 0.998-0.999)
• Interrator correlation (ICC = 0.998, 95% CI 0.996-0.999)
• Width of 95% Limits of Agreement (LoA) between app and universal goniometer: 10.26° (LoA = +4.51°, -5.75°)

In this study they considered 10° to be an acceptable interval (width) within 95% difference between measurements expected to lie (LoA = ±5°).  I am very curious to how standardization of using photography to measure will play out in the future to decrease error as this is a very fast method of getting objective data without having to have that "third hand" to position the patient and place the goniometer.

Coach's Eye I discussed earlier has an angle tool you can utilize to measure dynamic motions.  Here is another video I took of examples on how to use it.

Older post videos have not had such high resolution sorry about that, I will be uploading videos to youtube and linking to them from now on to improve the quality of videos.