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Physical Therapy in Sport 7 (2006) 191–194

www.elsevier.com/locate/yptsp

Original research

Assessing dynamic knee joint range of motion using siliconcoach

John Cronina,b,�, Michelle Nashb, Chris Whatmanb

aSchool of Exercise, Biomedical and Health Sciences, Edith Cowan University, 100 Joondalup Drive, Joondalup, Perth,

Western Australia 6027, AustraliabInstitute of Sport & Recreation Research New Zealand, Auckland University of Technology, Private Bag 92006, Auckland 1020, New Zealand

Received 4 April 2006; received in revised form 18 July 2006; accepted 19 July 2006

Abstract

Objective: Compared to measuring static range of motion (ROM) the assessment of dynamic ROM has received very little research

attention. The purpose of this study therefore was to determine the reliability of the siliconCOACH motion analysis system for

assessing dynamic ROM of the knee joint.

Design: Test–retest reliability.

Setting: Laboratory.

Participants: Ten male subjects unable to fully extend their knee at 901 of hip flexion.

Main Outcome Measures: Static and dynamic ROM over four separate occasions using a video camera and siliconCOACH

digitized footage.

Results: The variation between days for both static and dynamic measurements was minimal (CVo2.1%). With regards to test–

retest reliability, the ICC values, were high (ICCX0.89) for both assessment techniques and the static and dynamic ROM

measurements did not differ significantly (po0:05) on any given testing occasion.

Conclusions: The high ICC and low CVs indicate a high degree of stability between testing days for the procedures used in this study

to assess dynamic ROM. Software programmes such as siliconCOACH seem ideal for determining the end range of a movement for

both static and dynamic ROM and would seem to offer a functional and cost effective assessment strategy for those practitioners

and clinicians interested in the effects of various interventions on ROM.

r 2006 Elsevier Ltd. All rights reserved.

Keywords: Performance; Flexibility; Reliability; Coefficient of variation

1. Introduction

Possessing adequate range of motion (ROM) arounda joint is thought important for efficient movement anda reduced risk of injury in athletic and everyday activity(Bandy, Irion, & Briggler, 1998; Halbertsma, vanBolhuis, & Goeken, 1996). Measuring ROM thereforeis important to the clinician, conditioner, athlete and/orcoach for prognostic, diagnostic, training and monitor-

ee front matter r 2006 Elsevier Ltd. All rights reserved.

sp.2006.07.003

ing author. School of Exercise, Biomedical and Health

Cowan University, 100 Joondalup Drive, Joondalup,

Australia 6027, Australia. Tel.: +61 8 6304 5860;

5036.

ess: j.cronin@ecu.edu.au (J. Cronin).

ing purposes. With respect to ROM measurement thetechniques used can be broadly classified into static anddynamic techniques. Static ROM is a measure of theactual limits of motion around a joint or complex ofjoints, through a sustained end-range position. DynamicROM is an active movement of limbs to a point close toor beyond normal range.

The majority of research interested in ROM measuresuses static measurement techniques and tools such asflexometers, inclinometers and goniometers. The relia-bility of these techniques to measure knee joint ROMhas been estimated by a number of researchers (Bandyet al., 1998; DePino, WeBright, & Arnold, 2000; Feland,Myrer, & Merrill, 2001; Gajdosik, 1991; Knight,Rutledge, Cox, Acosta, & Hall, 2001; Power, Behm,

ARTICLE IN PRESSJ. Cronin et al. / Physical Therapy in Sport 7 (2006) 191–194192

Cahill, Carroll, & Young, 2004; Stewart & Sleivert,1998; Sullivan, Dejulia, & Worrell, 1992; Worrell,Smith, & Winegardner, 1994). Intraclass correlationco-efficients (ICC) ranging from 0.92 to 0.99and standard errors of measurement between 2.291and 2.911 have been typically reported by theseresearchers.

Compared to static ROM there appears to be apaucity of research that has investigated or useddynamic ROM assessment, and as such the reliabilityand validity of such assessment methods is unclear.Measurement of dynamic movement is often quantifiedas a static measure, where a goniometer has been used tomeasure the final ROM (Roberts & Wilson, 1999).Other methods have incorporated a five second hold atend range (Murphy, 1994). In terms of face validity,estimating a dynamic movement using a static measureseems problematic and may not accurately reflectfunctional ROM. Given this information and that agreat deal of research is concerned with changes indynamic ROM, it would seem prudent to developtechniques that can assess dynamic ROM. Hence thepurpose of this study was to determine the reliability ofsiliconCOACH sports analysis software for assessingdynamic ROM of the knee joint.

Fig. 1. Equipment, experimental set-u

2. Methods

2.1. Participants

Ten male subjects volunteered to participate in thestudy. Their mean (7SD) age, height, and mass were22.7 yr (73.6), 181.2 cm (76.51) and 84.9 kg (712.3),respectively. All subjects signed a consent form prior toall testing. The Auckland University of Technology’sEthics Committee approved the study. All subjectspassed exclusion criteria and were unable to fully extendtheir knee with 901 hip flexion.

2.2. Procedures

A video-camera (Sony DCR-TRV27E, Japan) andtripod were set at a standardised height and placementfrom a plinth. A wooden frame, which was designedspecifically for the experiment, was attached to theplinth. The wooden frame allowed the subjects right legto be strapped onto a crossbar, which enabled subjectsto extend their knee at 901 of hip flexion (see Fig. 1).This was to ensure accurate measurement of knee ROMduring the testing procedure and limit accessory move-ment. A seat belt was also used to fix the subjects left leg

p and siliconCOACH markings.

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Table 1

Reliability of static and dynamic ROM measures over four testing sessions

Test 1 (1) Mean (SD) Test 2 (1) Mean (SD) Test 3 (1) Mean (SD) Test 4 (1) Mean (SD) CV (%) ICC

Static 150.63 (5.77) 150.67 (6.75) 149.33 (6.57) 151.42 (5.68) 1.93 (0.92) 0.91

Dynamic 151.40 (5.40) 149.61 (7.26) 148.35 (6.06) 150.07 (5.94) 2.08 (1.09) 0.89

J. Cronin et al. / Physical Therapy in Sport 7 (2006) 191–194 193

to the plinth to help stabilise the pelvis and avoidlumbar flexion during testing. The video footageof the testing procedure was digitised using thesiliconCOACH (Version 6.5.1.0, siliconCOACH Ltd,Dunedin) computer programme. This enabled knee jointangles to be calculated between given markers as shownin Fig. 1.

Prior to testing, the subjects had their right legmarked with a permanent marker at the lateralepicondyle of the knee, and lateral malleolus of theankle. The alignment of the greater trochanter of the hipwas marked with white tape, attached to the plinth in avertical line to the greater trochanter. Identification oflandmarks was performed by a physiotherapist for everytesting occasion. These markers allowed for measure-ment of knee ROM from video-footage, using silicon-COACH software. Prior to ROM assessment, a 5minwarm-up was performed. This consisted of jogging at apace equivalent to 40% of the subjects perceivedmaximal speed. Knee ROM was measured immediatelyafter the warm-up. During dynamic ROM measure-ment, the subjects were required to maximallyextend and flex their right leg at a 1 s interval, asverbally cued by the investigator, for 10 repetitions. Thiswas immediately followed by static ROM measures,where the subjects sustained a three second hold ofmaximal knee extension, three times, with 5 s restperiods. This ROM assessment procedure was repeatedon four separate occasions over a 2-week period.Following the ROM measurements, all the maximaldynamic and static knee extension measures ofeach subject were calculated from the siliconCOACHsoftware.

2.3. Statistical analysis

A sample size of at least nine subjects was calculatedas sufficient to determine clinical or practical signifi-cance given Type I and Type II maximum rates ofstatistical error of 5% and 20% respectively andsmallest negative effects of 21 (Hopkins, 2006). Meansand standard deviations of all dynamic and staticmaximal knee extension angles were subsequently usedas measures of centrality and spread. The test–retestreliability of the ROM measures were estimated usingcoefficients of variation (CV ¼ SD/mean*100), andintra-class correlation coefficients (ICC 2,1—Shrout &Fleiss, 1979).

3. Results

The mean and standard deviations for the four testingoccasions ranged from 148.35 (76.06) to 151.42(75.68) (see Table 1). The variation between days forboth static and dynamic measurements was minimal(CVo2.1%). With regards to test–retest reliability, theICC values, were high (ICCX0.89) for both assessmenttechniques.

4. Discussion

To determine the measurement error associated withthe dynamic ROM assessment, a number of reliabilitymeasurements were used. A CV was calculated todetermine the ‘absolute consistency’ of scores acrossdays. The CV associated with the dynamic ROMtechnique was small and similar in magnitude to thestatic ROM variability. These are better values thanCVs calculated from other research assessing kneeextension ROM, which ranged from 2.0% to 3.96%(Roberts & Wilson, 1999), 6.79% to 7.95% (Rakos,Shaw, Fedor, LaManna, Yocum, & Lawrence, 2001)and 8.93% to 17.34% (Gajdosik, 1991). It would seemthat this protocol using siliconCOACH is just as, if notmore reliable than traditional methods for assessingROM including goniometry. Furthermore, as the CVfor the dynamic ROM assessment was small(CV ¼ 2.08%), it would seem that the number of trialscould be reduced and reliability would not be affected toany large extent.

The ICC was used as a measure of ‘relative reliability’or the degree to which individuals maintain theirposition in a sample with repeated measures. Nouniversally accepted standards have been adopted forqualitatively expressing the magnitude of the ICC values(Madson, Youdas, & Suman, 1999), however, oneproposed scheme has defined the ICC’s having thefollowing descriptors: 0.99–0.90 high reliability; 0.89–0.80 good reliability; 0.79–0.70 fair reliability and 0.69and below poor reliability (Meyers & Blesh, 1962). TheICC values estimated for the static and dynamic ROMassessments in this study were �0.90, suggestive of highreliability between testing occasions for both measures.These ICC values were similar (0.92–0.99) to thoseidentified in other studies (DePino et al., 2000; Sullivanet al., 1992; Worrell et al., 1994).

ARTICLE IN PRESSJ. Cronin et al. / Physical Therapy in Sport 7 (2006) 191–194194

5. Conclusions

The high ICC and low CVs indicate a high degree ofstability between testing days for the procedures used inthis study to assess dynamic ROM. Furthermore,compared to the reliability of the static ROM assessmentsof this study and other comparative studies, there wouldseem little difference in the precision of estimate of bothstatic and dynamic assessments. Software programmessuch as siliconCOACH seem ideal for determining theend range of a movement for both static and dynamicROM assessment. The tester needs to make sure suitablecare is taken during the assessment to ensure precisemarker placement during testing and consistency ofsubject positioning and motivational instruction, toensure reliable ROM measurement. It would seem thatthe dynamic ROM assessment technique used in thisstudy, offers a reliable and functional (face validity)assessment strategy for those practitioners and cliniciansinterested in the effects of various interventions ondynamic ROM. However, it should be realised that thedynamic ROM measure used in this study was assessedfrom a static standardised position and further research isneeded to determine the reliability associated with lesscontrolled and more dynamic movement.

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