Intra-rater reliability and agreement of various methods of measurement to assess dorsiflexion in the Weight Bearing Dorsiflexion Lunge Test (WBLT) among female athletes

Highlights

• Trigonometric calculation of DF angle has 3.28° of measurement error.

• Inclinometer based measurements (tibia and Achilles) have >6° of measurement error.

• Trigonometric calculation of DF should be considered the method of choice.

Abstract

Objectives

To examine the intra-observer reliability and agreement between five methods of measurement for dorsiflexion during Weight Bearing Dorsiflexion Lunge Test and to assess the degree of agreement between three methods in female athletes.

Design

Repeated measurements study design.

Setting

Volleyball club.

Participants

Twenty-five volleyball players.

Main outcome measurements

Dorsiflexion was evaluated using five methods: heel-wall distance, first toe-wall distance, inclinometer at tibia, inclinometer at Achilles tendon and the dorsiflexion angle obtained by a simple trigonometric function. For the statistical analysis, agreement was studied using the Bland-Altman method, the Standard Error of Measurement and the Minimum Detectable Change. Reliability analysis was performed using the Intraclass Correlation Coefficient.

Results

Measurement methods using the inclinometer had more than 6° of measurement error. The angle calculated by trigonometric function had 3.28° error. The reliability of inclinometer based methods had ICC values < 0.90. Distance based methods and trigonometric angle measurement had an ICC values > 0.90. Concerning the agreement between methods, there was from 1.93° to 14.42° bias, and from 4.24° to 7.96° random error.

Conclusion

To assess DF angle in WBLT, the angle calculated by a trigonometric function is the most repeatable method. The methods of measurement cannot be used interchangeably.

Introduction

Adequate tibiopedal ankle dorsiflexion (DF) is necessary for everyday activities such as walking, squatting or stair-climbing (Protopapadaki, Drechsler, Cramp, Coutts, & Scott, 2007). DF starts when the talus rolls forward relative to the leg and at the same time slides posteriorly (talocrural dorsiflexion) (Neumann, 2013). In weight-bearing, the talus movement is accompanied by a slight movement of the tibia which is defined as tibiopedal dorsiflexion (Neumann, 2013), and depending on the foot position, all the joints in the foot may contribute to this movement (Neumann, 2013). Generally speaking, tibiopedal DF movement decreases the angle between the foot and leg so that the distance between the toes and tibia-fibula complex is reduced. This movement is also essential in physical activities and sports, for instance, jumping (Fong et al., 2011, Prilutsky and Zatsiorsky, 1994). Likewise, reduced DF seems to be associated with a higher risk of injury (Gabbe et al., 2004, Malliaras et al., 2006, Martin et al., 2013, Martin et al., 2014, de Noronha et al., 2006) and it has been observed that ankle DF is altered after an ankle injury (Vicenzino, Branjerdporn, Teys, & Jordan, 2006). Consequently, DF is usually evaluated or measured in different fields: medicine, sports science and physical therapy. Unfortunately, there is no consensus among researchers and practitioners regarding the most appropriate method to assess DF (Gatt and Chockalingam, 2011, Martin and McPoil, 2005). Therefore, each clinician and researcher uses a different method, making a comparison between studies extremely complex (Martin & McPoil, 2005).

Generally, DF is evaluated with the participant non-weight bearing (in supine or prone position), using a goniometer or inclinometer. The reliability of these measurements has been questioned (Elveru et al., 1988, Gatt and Chockalingam, 2011), and serious doubts have arisen as to the value of the research performed with this method (Gatt & Chockalingam, 2011). In addition, when evaluating the functionality of the ankle it seems impractical to measure non-weight-bearing DF since it does not reflect the movements required for dynamic activities (McPoil & Cornwall, 1996). Moreover it has been demonstrated that the non-weight-bearing DF is not related to weight-bearing DF measurements (Baggett and Young, 1993, Rabin and Kozol, 2012). On the other hand, the Weight-bearing Dorsiflexion Lunge Test (WBLT) has shown better reliability than non-weight-bearing DF tests (Denegar et al., 2002, Krause et al., 2011). Therefore, unless the participant has weight-bearing restrictions, it seems more appropriate to evaluate weight-bearing DF (Wilken, Rao, Estin, Saltzman, & Yack, 2011), preferably with the WBLT.

For the WBLT, the participant is required to align the heel and first toe in the center of a line drawn on the floor (Bennell et al., 1998, Dennis et al., 2008). Then they have to touch the line marked on the wall with their knee without lifting the heel of the tested foot off the ground (Fig. 1). The participant is allowed to make as many attempts as they deem appropriate to achieve the maximum distance from the wall to the foot.

The evaluation of the maximum DF in WBLT can be carried out using various measurement methods. The most common instrument used to assess DF is the inclinometer, although the location of this instrument varies across studies: Achilles tendon (Burns and Crosbie, 2005, Bennell et al., 2001), tibia (Barton et al., 2010, Bennell et al., 1998, Crossley et al., 2007, Nitz and Choy, 2004, Rabin and Kozol, 2010) or the lateral side of the tested leg (Krause et al., 2011). Alternatively, Bennell et al. (1998) proposed measuring the distance between the first toe of the tested leg and the wall. However, the comparison between participants is limited, because assuming that two participants had the same DF angle, the person with a longer foot would register a shorter distance (Bennell et al., 1998). An interesting method that allows comparison between participants could be the one proposed by Pope, Herbert, and Kirwan (1998). These authors measured the distance from the heel to the wall and the distance from the ground to the knee. From these two distances, the DF angle was calculated using a simple trigonometric function. However the reliability of this method was not studied in the original paper (Pope et al., 1998) and, to our knowledge, has not been studied so far.

There is currently a lack of agreement in the scientific community concerning how the DF should be evaluated in the WBLT. Moreover, the methods proposed by the previous literature are of questionable reliability, and are also complex, requiring specific equipment and trained personnel to carry them out. Therefore, it is necessary to establish the reliability and agreement (measurement error) of the measurement methods in the WBLT and determine which method is most appropriate. The primary objective of this study is to determine the intra-observer reliability and agreement of inclinometer based methods (Achilles and tibia); toe-wall, heel-wall and ground-knee distances and the measurement of the DF angle calculated by a trigonometric function in female athletes, and to establish which is the most reliable method. The secondary objective of the research is to determine the degree of agreement between inclinometer methods (Achilles and tibia) and trigonometric angle method and determine whether they can be used interchangeably.