Reliability and criterion validity of the “Gyroscope” application of the iPod ™ for measuring lumbar range of motion

Abstract

BACKGROUND:

Recent technologies, such as the iPod, are often equipped with an accelerometer and magnetometer, which, through software applications, can perform various inclinometric functions. These applications have the potential to measure and quantify range of motion (ROM).

OBJECTIVE:

The purpose of this study was to estimate the iPod “Gyroscope” application intra- and inter-rater reliability as well as its criterion validity in healthy participants lumbar ROM assessment.

METHODS:

The sample consisted of 29 healthy participants. For the estimation of intra- and inter-reliability, two examiners measured the lumbar ROM of each participant twice using the iPod. To estimate the criterion validity, the measures were compared to those obtained with the Back Range of Motion Device (BROM; lateral flexion) and the double inclinometer (flexion and extension). Reliability and validity were then established using the intraclass correlation coefficient (ICC).

RESULTS:

We observed a moderate to high intra-rater reliability (ICCs $=$ 0.67–0.91) and a moderate to high inter-rater reliability for each movement (ICCs $=$ 0.72–0.89). For the criterion validity, the ICCs were all high (ICCs $=$ 0.65–0.89).

CONCLUSION:

Our results provide evidence that the iPod “Gyroscope” application can be used to assess lumbar ROM for all movements.

Keywords

Range of motion outcome measures reliability criterion validity iPod lumbar spine digital inclinometer

1. Introduction

Low back pain (LBP) is a major health problem in Western populations [1]. It is responsible for important societal costs such as medical consultation [2], work absenteeism and decreased productivity [3, 4]. With a lifetime prevalence of 84%, it is the most important musculoskeletal disorder which often affects workers who need to perform heavy lifting, including lumbar flexion or trunk rotation [5, 6].

Impairments and limitations related to LBP are multiple and include decreased joint range of motion (ROM) [7]. ROM measurement is an integral part of the physiotherapy assessment since it is used as an objective outcome measure to quantify deficits and their improvements over time, to establish a diagnosis of functional performance, to provide information for prognosis, and also to prepare an individualized intervention plan [8, 9, 10].

Several instruments and/or measurement techniques are used to assess lumbar ROM, such as: the Schoeber and modified Schoeber technique [11, 12], the finger-to-ground distance using a measuring tape [13], the Back Range of Motion Device (BROM) [14], the universal goniometer [15], or the inclinometer (simple, electronic, or double inclinometer). The BROM has a high reliability for the measurement of lumbar and lateral flexion (ICC $=$ 0.77–0.94) [16, 17, 18], but has lower reliability for extension and rotation movements (ICC $=$ 0.58–0.76) [19]. In comparison, the double inclinometry was shown to be reliable ( $r=$ 0.90) [20] and valid for lumbar flexion ( $r=$ 0.98) and extension ( $r=$ 0.75) [21]. Further studies concluded that the EDI-320, an electronic inclinometer, had moderate to high reliability and validity in the measurement of lumbar [17] and cervical ROM [22, 23]; it is however no longer available. According to the literature, the inclinometer [24], using the double inclinometry technique [25], and the BROM [16], seem to be the two most reliable and valid instruments to measure lumbar ROM among all those currently available for health professionals. Nonetheless, some of these instruments are expensive and less accessible or convenient in clinical settings.

Most recent electronic devices, such as the iPod, are equipped with an accelerometer and a magnetometer, along with applications that enable these devices to measure different angles using the inclinometry functions. The iPod is easy to use and is accessible to most clinicians; it can be used to obtain objective clinical data, such as ROM of the lumbar spine. Kolber et al. [26] concluded that the “iHandy” iPhone application had high reliability (ICC: 0.82–0.96) and high validity (ICC: 0.86–0.96) for lumbar, thoracolumbar, and thoracolumbar lateral flexion as well as thoracolumbar extension when compared to a gravity-based bubble inclinometer. The “goniometer software” application was also shown to be reliable (ICC: 0.81–0.92) and valid ( $r=$ 0.95) for lumbar flexion [27], neglecting however to isolate pure lumbar movements measurement such as extension and lateral flexion. In a study by Pourahmadi et al. [28], the authors demonstrated that the “TiltMeter – advanced level and inclinometer” application had high reliability (ICC $\geqslant$ 0.77) as well as high validity ( $r\geqslant$ 0.86) for isolated lumbar flexion and extension movements, when compared to a standard gravity-based inclinometer (model A-300; Vertex Co., Taiwan). However, no measurements were taken for lateral flexions of the lumbar spine [28].

Considering the current state of the literature and the availability of electronic devices [29], we aimed to provide evidence of intra-rater and inter-rater reliability as well as criterion validity of the measurement of lumbar ROM (flexion, extension, and lateral flexion) using the iPod “Gyroscope” application on healthy participants.

2. Methodology

2.1 Study design

A correlational design (analytical observational study) was used to determine the iPod’s reliability through intra- and inter-rater consistency. Regarding the instrument criterion validation, we used the BROM (for lateral flexion) and the double inclinometer (for flexion and extension movements) as gold standards.

2.2 Selection and description of participants

The sample included 29 healthy volunteers (11 men and 18 women) aged between 19 and 34 years old (mean: 21.6 $\pm$ 1.6). The inclusion criterion was to be over 18 years of age. Exclusion criteria included neurological diseases (multiple sclerosis, radiculopathy, etc.), neurocognitive conditions (dementia, amnesia, delirium, etc.), neuromusculoskeletal or systemic conditions that could influence the outcomes. Individuals with a history of lumbar pain or other symptoms in the last month were also excluded.

Convenience sampling was used, in which participants were recruited from volunteers within the authors’ network and received no financial compensation. The study was approved by the Université de Sherbrooke Hospital Ethics Review board (project #10-199). All subjects read the protocol and provided written consent prior to participation.

Table 1
Validity estimates of the instruments used as gold standards

Instruments	Lumbar flexion	Lumbar extension	Lateral flexion
BROM	–	–	ICC $=$ 0.85–0.91
Double inclinometer	$r=$ 0.62–0.95	$r=$ 0.75–0.82	–

2.3 Instrument

2.3.1 iPod application

The iPod 5th generation was used for this study. Its dimensions are 123.4 mm (height) $\times$ 58.6 mm (width) $\times$ 6.1 mm (depth) and it weighs 88 g.

The angle measurement application “Gyroscope” by Acrossair (http://appgravity.com/ios-apps/entertainme nt/ios:381953722?pub=acrossair) was downloaded to the iPod from the Canadian Apple Application store, allowing us to measure angles in 3 planes: frontal, sagittal, and horizontal. This application is free and can be used with the iPhone 4, iPod touch 4th generation, and all newer models. It uses an accelerometer (hardware – LIS302DL accelerometer) with three axes of motion that can detect the position and orientation of the device in space thanks to the direction of the gravity force. The application also uses a magnetometer (hardware – AKM AK8975 magnetometer) built into the iPod that uses the magnetic north to create three axes of motion related to the Earth’s magnetic field. In this study, we used “pitch” as the reference axis for our data.

2.3.2 Back Range of Motion Device (BROM)

The BROM was used as a gold standard for the measurement of lateral flexion movements. This instrument has a gravitational inclinometer at its center and measures movements in the frontal plane. This tool was chosen as a gold standard considering its high validity (Table 1) documented for lateral flexion movements [16, 17].

2.3.3 Double inclinometer

The double inclinometry technique was used as the gold standard to measure movements in the sagittal plane (lumbar flexion and extension). This device has a gravitational inclinometer that allows measuring the angles from the horizontal axis (model DC-360; Acumar ${}^{\text{TM}}$ ). This technique combines two digital inclinometers positioned on S1 and T12 respectively, which isolate pure lumbar movements. The double inclinometer was used as a gold standard considering its higher validity (Table 1) over the BROM for these two lumbar movements [21, 30, 31].

2.4 Procedures

2.4.1 Selection of examiners for the reliability study

Five physiotherapy students received three hours of training to properly use and manipulate the iPod, the BROM, and the double inclinometer. Preliminary tests were conducted on four healthy volunteers in order to select the two evaluators (among the five students) with the highest intra-rater reliability (ICCs $>$ 0.80). The selected evaluators then practiced their techniques for one more hour on four participants to standardize the procedure. In total, they received four hours of training prior to actual testing in order to reduce a potential information bias. The same two evaluators with the same two iPods evaluated all participants.

2.4.2 Selection of examiners for the validity study

Of the two chosen examiners, the one with the best intra-rater reliability was selected to take measurements with the gold standard tool. This was done to decrease the risk of information (evaluation) bias.

2.4.3 Data collection procedures

Data was collected between October 1 ${}^{\text{st}}$ , 2014 and December 15 ${}^{\text{th}}$ , 2014 at the Université de Sherbrooke School of Rehabilitation. During each session, participants were first informed about the procedure; then, the spinous processes of S1 and T12 were identified in the prone position by manual palpation and marked with a pen by the same evaluator. The S1 spinous process was localized as one spinous process above the two posterior superior iliac spines midpoint. From that point, the T12 spinous process was localized by manual palpation. The localization of these spinous processes was verified by a second evaluator and the marks were used to guide the placement of the measuring instruments. To reduce the risk of a potential systematic error due to the gain of ROM over the course of the evaluation, a warm-up session including two sets of six repetitions of each evaluated movement was performed [32]. One repetition consisted of an anterior lumbar flexion, a right lateral flexion, left lateral flexion and a lumbar extension. These movements were clearly explained to the participants before entering the measurement room.

Figure 1.

Measurement of the range of motion of the lumbar spine in the sagittal plane: (1) starting position, (2) flexion end position, (3) extension end position.

Figure 2.

Measurement of the range of motion of the lumbar spine in the frontal plane: (1) starting position, (2) left lateral flexion end position, (3) right lateral flexion end position.

Each session lasted approximately one hour and involved two to four participants, each participant was evaluated one at a time. An observer noted the measures (angles) verbally given by each evaluator. The participants had to perform full active movements of lumbar flexion, extension, and lateral flexion and were instructed to go as far as possible for each movement. The measurements of lumbar flexion and extension were taken by positioning the base of the iPod on the T12 spinous process, then on the S1 spinous process (Fig. 1). Measurements of right and left lateral flexion were taken by positioning the side edge of the iPod directly below the horizontal line drawn at the T12 spinous process (Fig. 2). The iPod was held tightly in place by the evaluator during the movement. Each movement was observed by the evaluator and corrected if any substitution occurred. The examiner made sure the device was positioned correctly through the movements and during the session. The order in which each movement was evaluated was randomly chosen by the observer in order to minimize a potential recall bias from the examiner. For the movements in the sagittal plane, ROM measurement was obtained by subtracting the T12-S1 angle measurements between the initial and final positions. The movements in the frontal plane were also obtained by calculating the angle difference between the initial and final positions of T12-S1. These calculations were based on the dual inclinometer and BROM protocols.

2.4.4 Reliability study procedure

Each experimental session involved 3–4 patients at a time, where both examiners and observers entered two different rooms; each assessing all lumbar movements with the iPod. The examiners and observers then changed rooms clockwise until they had taken two measures of each movement for every participant. This allowed us to gather estimates of both intra- and inter-rater reliability.

2.4.5 Validity study procedure

The selected evaluator performed a third round of movements assessment with each participant, this time using the BROM (lateral flexion) and double inclinometer (flexion/extension). Measures of validity were always taken last in order to minimize a potential information bias.

2.5 Sample size

In order to observe a minimal correlation of 0.65 and with a Cronbach alpha below 0.05, a minimum of 24 subjects were required.

Table 2
Reference values for the interpretation of the ICCs

		Low	Moderate	High
ICC	Reliability	$\leqslant$ 0.4	0.40–0.75	$\geqslant$ 0.75
	Validity	$<$ 0.50	0.50–0.65	$>$ 0.65

Table 3

Intra-rater reliability in measurement of lumbar range of motion with iPod

Movement	ICC	95% CI	$p$	ICC	95% CI	$p$
	Rater 1			Rater 2
Flexion	0.859	0.721–0.931	$<$ 0.001	0.689	0.436–0.841	$<$ 0.001
Extension	0.762	0.555–0.881	$<$ 0.001	0.672	0.410–0.831	$<$ 0.001
Right lateral flexion	0.887	0.773–0.945	$<$ 0.001	0.905	0.809–0.955	$<$ 0.001
Left lateral flexion	0.755	0.542–0.877	$<$ 0.001	0.850	0.705–0.927	$<$ 0.001

2.6 Data analysis

To determine the intra- and inter-rater reliability of the instruments, the averages of intra-class correlation coefficients (ICC) were used for each movement more specifically, using a model 3 ICC (“two-way mixed model with measures of consistency”). The ICC is a statistical measure designed to quantify the importance and direction of association between the two variables. The values can vary between $-$ 1 (perfectly negative association) and $+$ 1 (perfectly positive association). An ICC less than 0.4 may be considered as poor reproducibility; a value between 0.4 and 0.75 indicates average reproducibility and an ICC greater than 0.75 indicates high reproducibility (Table 2) [33].

ICCs were also used to calculate the validity. ICCs are in this case more accurate than Pearson’s correlation coefficient because they take into consideration certain bias such as systematic errors. For instance, if one examiner always measures 5 ${}^{\circ}$ more than another examiner, Pearson’s would still show a high correlation coefficient while the ICC would show a lower value since it verifies if the measurements are the same and not only associated. An ICC below 0.5 indicates poor validity, between 0.5 and 0.65 a moderate to high validity, and above 0.65 a high validity (Table 2).

The level of significance was $p<$ 0.05. Data were analyzed with SPSS Statistics 23 (IBM Corp., Chicago, IL, USA).

3. Results

3.1 Intra-rater reliability

The results of the intra-rater reliability are presented in Table 3. Rater 1 obtained the highest ICCs ranging from 0.76 to 0.89 ( $p<$ 0.001); rater 2 showed lower ICCs, ranging from 0.67 to 0.91 ( $p<$ 0.001). Only flexion and extension movements for rater 2 had ICC $<$ 0.75 ( $p<$ 0.001). In general, lateral flexion demonstrated the best ICCs while the lowest ICCs were observed for the extension movement.

3.2 Inter-rater reliability

The results of inter-rater reliability are presented in Table 4. They were obtained by comparing the average of the range values for all movements between the two evaluators. The inter-rater reliability ICCs ranged from 0.72–0.89 ( $p<$ 0.001). Lateral flexion (ICCs: 0.879–0.890; $p<$ 0.001) and extension (ICC: 0.840; $p<$ 0.001) had the best inter-rater reliability.

Table 4
Inter-rater reliability in measurement of lumbar range of motion with iPod

Movement	ICC	95% CI	$p$
Flexion	0.718	0.465–0.860	$<$ 0.001
Extension	0.840	0.689–0.921	$<$ 0.001
Right lateral flexion	0.879	0.760–0.941	$<$ 0.001
Left lateral flexion	0.890	0.730–0.952	$<$ 0.001

Table 5

Criterion validity of the iPod when compared to dual inclinometer and BROM

Movement	ICC	95% CI	$P$
Flexion	0.703	0.418–0.858	$<$ 0.001
Extension	0.654	0.331–0.833	$<$ 0.001
Right lateral flexion	0.854	0.704–0.932	$<$ 0.001
Left lateral flexion	0.892	0.776–0.950	$<$ 0.001

3.3 Criterion validity

The validity results are shown in Table 5. By comparing the values obtained by the iPod and the values obtained with the gold standards (BROM and double inclinometer), we observed that the validity was high for all movements, with ICCs ranging from 0.65 to 0.89 ( $p<$ 0.001).

4. Discussion

The objective of this study was to determine estimates of intra and inter-rater reliability as well as criterion validity of the iPod “Gyroscope” application for the measurement of lumbar ROM in healthy participants. The validity was determined by comparing the iPod’s measurements with the ones obtained by a dual inclinometer (flexion/extension) and the BROM device (lateral flexions).

4.1 Reliability findings

We found moderate to high intra-rater reliability for all movements. Similar results were observed by Kolber et al. [26] using the iPhone’s iHandy application, for flexion (ICC: 0.88) and lateral flexions (ICC: 0.82–0.84). They observed higher intra-rater reliability for extension (ICC: 0.80). However, they measured the thoracolumbar extension and lateral flexions, which is difficult to compare with our findings, as we measured isolated lumbar movements. Another study by Pourahmadi et al. [28] reported ICC scores slightly higher than ours using the “TiltMeter” application for the movement of flexion (ICC: 0.92) and extension (ICC: 0.91–0.92). These results could be explained by the fact that the evaluators in the later study were experienced clinicians whereas in our study, they were two novice physical therapy students. However, as all estimates of intra-rater reliability remain high (ICC $\geqslant$ 0.75), these differences in intra-rater reliability between studies are not likely to be clinically significant.

Inter-rater reliability estimates were found to be moderate for flexion and high for extension and lateral flexions. In comparison, Kolber et al. [26] (ICC: 0.88) and Pourahmadi et al. [28] (ICC: 0.89) observed higher inter-rater reliability for flexion and similar ICCs for the other movements. The difference between their results and ours could be explained by the fact that inter-rater reliability is affected by intra-rater reliability. Considering that evaluator #2 intra-rater reliability scores were in the “moderate” range, this may have had a direct impact on inter-rater reliability.

4.2 Validity findings

Lumbar ROM measurements with the iPod “Gyroscope” application were comparable (high validity) to those obtained with the gold standards for lateral flexion (ICCs $=$ 0.85–0.89). We observed however lower validity estimates (moderate) for flexion (ICC $=$ 0.70, 95% CI: 0.42–0.86) and extension (ICC $=$ 0.65, 95% CI: 0.33–0.83). Other studies also reported similar validity findings [26]. The lower validity observed for the sagittal plane could be explained by the different shapes of the two instruments (iPod vs double inclinometer) and the slight difficulty to keep a constant contact with the skin while using the iPod (i.e. positioning error). In addition, we noted that in short-statured participants showing high amplitude in lumbar extension, the two parts of the double inclinometer came into contact when measuring extension. Thus, this double-inclinometer source of error may affect validity estimates as this tool may not exhibit 100% validity.

4.3 Strengths and limitations

4.3.1 Strengths

First, regarding the evaluators, the selection was based on their ability to use the device; those two who showed the highest intra-rater reliability scores during the preliminary tests were selected for reliability analysis. The same principle was used for validity analysis, where only one evaluator (highest intra-rater reliability score) took all measurements. This aspect made it possible to reduce sources of error occurring from the evaluator (a potential information bias). In addition, the iPod measurements were taken in a random order to minimize the examiners’ recall bias. In addition, the gold standard measurements with the dual inclinometer and the BROM, were taken following the two turns with the iPods – again to reduce the evaluators’ potential information bias (evaluators did not know the “real” ROM while taking measurements with the iPod). Finally, the evaluators were instructed to collect data in a random order and to obtain the raw angles for each measurement, as the final ROM value had to be calculated a posteriori to control for potential recall bias.

Second, regarding the participants, bias and errors were minimized as all participants received the same instructions before each measurement. In addition, the observers ensured the quality of the movements by alerting the examiner for any compensations. Also, participants performed a short “warm-up” session before measurements were taken – this allowed them to practice what was expected of them and prevented a gain in joint ROM after several repetitions. Clearly, efforts were made to isolate sources of error coming from the instrument tested.

4.3.2 Limitations

First, the collection was done only on healthy and young participants, which decreases the external validity of the study. Furthermore, the use of the dual inclinometer was cumbersome in high lumbar extension amplitude as well as in short-statured participants since both inclinometers came into contact at end-range.

Second, although many similar devices are equipped with a gyroscope, we wonder if our findings could apply to other types/brands of smartphones? Recently, Wellmon et al. [34] reported that Apple iPhones, LG Android phones, and Samsung SIII Android phones, all with different types of gyroscope, had very good concurrent validity (a mean difference of $-$ 0.4 to 1.2) between them. Therefore, future studies should examine different kinds of apps (software) using the same gyroscope (hardware) on different types of smartphones.

4.4 Implications for practice

The use of mobile devices by healthcare professionals to enhance communication and information gathering (i.e. diagnosis, measurements) is clearly documented. Mobile applications can allow healthcare professionals to better obtain, manage, and use the clinical data they acquire [35]. Although our findings support that the iPod has sufficient reliability and validity to lead towards its clinical use, it would be important, prior to adoption, to improve instrument positioning and further examine instrument properties to use it with participants who experience low back pain.

5. Conclusion

This study supports the use of the “Gyroscope” application for the measurement of lumbar ROM for flexion, extension, and lateral flexion in healthy people. The iPod is an accessible device, easy to use, reliable, and valid. It presents a good potential for clinical use to objectify ROM deficits. Yet, as we provided evidence of validity via healthy subjects, it would be relevant to obtain estimation of reliability, validity, trueness, and minimal detection changes on participants experiencing low back pain.

Footnotes

Conflict of interest

None to report.

References

Hoy

March

Brooks

Blyth

Woolf

Bain

, et al. The global burden of low back pain: estimates from the Global Burden of Disease 2010 study. Ann Rheum Dis 2014; 73: 968–74. doi: 10.1136/annrheumdis-2013-204428.

Mantyselka

Kumpusalo

Ahonen

Kumpusalo

Kauhanen

Viinamaki

, et al. Pain as a reason to visit the doctor: a study in Finnish primary health care. Pain 2001; 89: 175–80.

Dagenais

Caro

Haldeman

. A systematic review of low back pain cost of illness studies in the United States and internationally. Spine J 2008; 8: 8–20. doi: 10.1016/j.spinee.2007.10.005.

Stewart

Ricci

Chee

Morganstein

Lipton

. Lost productive time and cost due to common pain conditions in the US workforce. J Am Med Assoc 2003; 290: 2443–54. doi: 10.1001/jama.290.18.2443.

Picavet

Schouten

. Musculoskeletal pain in the Netherlands: prevalences, consequences and risk groups, the DMC (3)-study. Pain 2003; 102: 167–78.

Waddell

Burton

. Occupational health guidelines for the management of low back pain at work: evidence review. Occup Med (Lond) 2001; 51: 124–35.

Burton

Tillotson

Troup

. Variation in lumbar sagittal mobility with low-back trouble. Spine (Phila Pa 1976) 1989; 14: 584–90. doi: 10.1097/00007632-198906000-00007.

Greenwood

. Low-back impairment-rating practices of orthopaedic surgeons and neurosurgeons in West Virginia. Spine (Phila Pa 1976) 1985; 10: 773–6.

Reese

Bandy

. Joint Range of motion and muscle lenght testing. 2002.

10.

Delitto

George

Van Dillen

Whitman

Sowa

Shekelle

, et al. Low back pain. J Orthop Sports Phys Ther 2012; 42: A1–57. doi: 10.2519/jospt.2012.42.4.A1.

11.

Miller

Mayer

Cox

Gatchel

. Reliability problems associated with the modified Schöber technique for true lumbar flexion measurement. Spine (Phila Pa 1976) 1992; 17: 345–8. doi: 10.1097/00007632-199203000-00017.

12.

Reynolds

PMG

. Measurement of spinal mobility: acomparison of three methods. Rheumatology 1975; 14: 180–5. doi: 10.1093/rheumatology/14.3.180.

13.

Gauvin

Riddle

Rothstein

. Reliability of clinical measurements of forward bending using the modified fingertip-to-floor method. Phys Ther 1990; 70: 443–7. doi: 10.1093/ptj/70.7.443.

14.

Portek

Pearcy

Reader

Mowat

. Correlation between radiographic and clinical measurement of lumbar spine movement. Rheumatology 1983; 22: 197–205. doi: 10.1093/rheumatology/22.4.197.

15.

Burdett

Brown

Fall

. Reliability and validity of four instruments for measuring lumbar spine and pelvic positions. Phys Ther 1986; 66: 677–84. doi: 10.1093/ptj/66.5.677.

16.

Breum

Wiberg

Bolton

. Reliability and concurrent validity of the BROM II for measuring lumbar mobility. J Manipulative Physiol Ther 1995; 18: 497–502.

17.

Tousignant

Morissette

Murphy

. Criterion validity study of lumbar goniometers BROM II and EDI-320 for range of motion of lumbar flexion of low back pain patients. J Back Musculoskelet Rehabil 2002; 16: 159–67.

18.

Rondinelli

Murphy

Esler

Marciano

Cholmakjian

. Estimation of normal lumbar flexion with surface inclinometry. A comparison of three methods. Am J Phys Med Rehabil 1992; 71: 219–24.

19.

Kachingwe

Phillips

. Inter- and intrarater reliability of a back range of motion instrument. Arch Phys Med Rehabil 2005; 86: 2347–53. doi: 10.1016/j.apmr.2005.07.304.

20.

Keeley

Mayer

Cox

Gatchel

Smith

Mooney

. Quantification of lumbar function. Part 5: Reliability of range-of-motion measures in the sagittal plane and an in vivo torso rotation measurement technique. Spine (Phila Pa 1976) 1986; 11: 31–5. doi: 10.1097/00007632-198601000-00009.

21.

Saur

PMM

Ensink

FBM

Frese

Seeger

Hildebrandt

. Lumbar range of motion: reliability and validity of the inclinometer technique in the clinical measurement of trunk flexibility. Spine (Phila Pa 1976) 1996; 21: 1332–8. doi: 10.1097/00007632-199606010-00011.

22.

Lee

Nicholson

Adams

. Cervical range of motion associations with subclinical neck pain. Spine (Phila Pa 1976) 2004; 29: 33–40. doi: 10.1097/01.BRS.0000103944.10408.BA.

23.

Tousignant

Smeesters

Breton

A-M

Breton

Corriveau

. Criterion validity study of the cervical range of motion (CROM) device for rotational range of motion on healthy adults. J Orthop Sports Phys Ther 2006; 36: 242–8.

24.

Mayer

Tencer

Kristoferson

Mooney

. Use of noninvasive techniques for quantification of spinal range-of-motion in normal subjects and chronic low-back dysfunction patients. Spine (Phila Pa 1976) 1984; 9: 588–95. doi: 10.1097/00007632-198409000-00009.

25.

Nitschke

Nattrass

Disler

Chou

Ooi

. Reliability of the american medical association guides’ model for measuring spinal range of motion its implication for whole-person impairment rating. Spine (Phila Pa 1976) 1999; 24: 262–8. doi: 10.1097/00007632-199902010-00013.

26.

Kolber

Pizzini

Robinson

Yanez

Hanney

. The reliability and concurrent validity of measurements used to quantify lumbar spine mobility: an analysis of an iphone® application and gravity based inclinometry. Int J Sports Phys Ther 2013; 8: 129–37.

27.

Bedekar

Suryawanshi

Rairikar

Sancheti

Shyam

. Inter and intra-rater reliability of mobile device goniometer in measuring lumbar flexion range of motion. J Back Musculoskelet Rehabil 2014; 27: 161–6. doi: 10.3233/BMR-130431.

28.

Pourahmadi

Taghipour

Jannati

Mohseni-Bandpei

Ebrahimi Takamjani

Rajabzadeh

. Reliability and validity of an iPhone (®) application for the measurement of lumbar spine flexion and extension range of motion. PeerJ 2016; 4: e2355. doi: 10.7717/peerj.2355.

29.

Gill

Kamath

Gill

. Distraction: an assessment of smartphone usage in health care work settings. Risk Manag Healthc Policy 2012; 5: 105–14. doi: 10.2147/RMHP.S34813.

30.

Shirley

O’Connor

Robinson

MacMillan

. Comparison of lumbar range of motion using three measurement devices in patients with chronic low back pain. Spine (Phila Pa 1976) 1994; 19: 779–83.

31.

Adams

Dolan

Marx

Hutton

. An electronic inclinometer technique for measuring lumbar curvature. Clin Biomech (Bristol, Avon) 1986; 1: 130–4. doi: 10.1016/0268-0033(86)90002-1.

32.

Lieber

Bodine-Fowler

. Skeletal muscle mechanics: implications for rehabilitation. Phys Ther 1993; 73: 844–56.

33.

Fleiss

. Design and analysis of clinical experiments. New York, NY, U.S.A.: Wiley Classic Library; 1999.

34.

Wellmon

Gulick

Paterson

Gulick

. Validity and Reliability of Two Goniometric Mobile Apps: Device, Application and Examiner Factors. J Sport Rehabil 2015. doi: 10.1123/jsr.2015-0041.

35.

Ventola

. Mobile devices and apps for health care professionals: uses and benefits. P T 2014; 39: 356–64.

Reliability and criterion validity of the “Gyroscope” application of the iPod ™ for measuring lumbar range of motion

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSION:

Keywords

1. Introduction

2. Methodology

2.1 Study design

2.2 Selection and description of participants

Table 1 Validity estimates of the instruments used as gold standards

2.3.1 iPod application

2.3.2 Back Range of Motion Device (BROM)

2.3.3 Double inclinometer

2.4 Procedures

2.4.1 Selection of examiners for the reliability study

2.4.2 Selection of examiners for the validity study

2.4.3 Data collection procedures

2.4.5 Validity study procedure

2.5 Sample size

Table 2 Reference values for the interpretation of the ICCs

3. Results

3.1 Intra-rater reliability

3.2 Inter-rater reliability

Table 4 Inter-rater reliability in measurement of lumbar range of motion with iPod

4. Discussion

4.1 Reliability findings

4.2 Validity findings

4.3 Strengths and limitations

4.3.1 Strengths

4.3.2 Limitations

4.4 Implications for practice

5. Conclusion

Footnotes

Conflict of interest

References

Table 1
Validity estimates of the instruments used as gold standards

Table 2
Reference values for the interpretation of the ICCs

Table 4
Inter-rater reliability in measurement of lumbar range of motion with iPod