- Email: [email protected]
Intra-rater repeatability of the Oxford foot model in healthy children in different stages of the foot roll over process during gait
Gait & Posture 30 (2009) 118–121
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
Short communication
Intra-rater repeatability of the Oxford foot model in healthy children in different stages of the foot roll over process during gait D.J. Curtis a,b,*, J. Bencke a, J.A. Stebbins c, B. Stansfield d a
Gait Analysis Laboratory, Dept of Orthopedic Surgery, Hvidovre University Hospital, Kettegaard Alle´ 30, DK-2650 Hvidovre, Denmark Dept of Physiotherapy, Hvidovre University Hospital, Kettegaard Alle´ 30, DK-2650 Hvidovre, Denmark c Oxford Gait Laboratory, Nuffield Orthopaedic Centre, Windmill Road, Headington, Oxford OX3 7LD, UK d School of Health and Social Care, Glasgow Caledonian University, Glasgow, UK b
A R T I C L E I N F O
A B S T R A C T
Article history: Received 8 August 2008 Received in revised form 13 February 2009 Accepted 18 February 2009
Background: The repeatability of the Oxford foot model has been reported, but possible variations in the repeatability during the foot roll over process have not been examined. The aim of this study was to determine the relative and absolute repeatability of the model for each stage of the foot roll over process during gait and to compare foot kinematic data from this study with that from another centre as a preliminary examination of the model’s inter-centre repeatability and validity. Method: Eight healthy children were tested twice at the gait laboratory. Foot kinematics from this study were plotted against those from an earlier repeatability study and repeatability statistics calculated for the three rockers of stance phase and swing phase. Results: Foot kinematics from this study and an earlier repeatability study produced similar kinematic patterns and joint angle ranges, but there were offsets in the absolute joint angles in the frontal and transverse planes. Relative and absolute repeatability were best in the sagittal plane (flexion/extension) with the poorest repeatability in the transverse plane (rotation and abduction/adduction). There was little difference in repeatability between the three rockers. Typical error of measurement varied between planes and segments from 0.98 for maximum forefoot dorsiflexion in second rocker to 8.68 for maximum hindfoot internal rotation in first rocker. Discussion: Repeatability varied markedly between planes and segments but was consistent throughout the gait cycle. Further studies are needed to determine the inter-centre repeatability and validity of the model. ß 2009 Elsevier B.V. All rights reserved.
Keywords: Foot Kinematics Repeatability Instrumented gait analysis Oxford foot model
1. Introduction A number of models have been suggested to allow a more detailed analysis of foot kinematics [1–8]. The Oxford foot model appears from two published studies [5,9] to have a good repeatability in healthy subjects but there are no published studies examining the inter-centre repeatability or validity of the model. As this model is used clinically to determine the effect of an intervention on foot kinematics in a given phase of the gait cycle, it was felt that the repeatability of the model should be examined for each of these phases as it was possible that factors such as mechanical loading (e.g. heel pad deformation) and skin move-
* Corresponding author at: Gait Analysis Laboratory, Dept of Orthopedic Surgery, Hvidovre University Hospital, Kettegaard Alle´ 30, DK-2650 Hvidovre, Denmark. Tel.: +45 3632 6248. E-mail address: [email protected] (D.J. Curtis). 0966-6362/$ – see front matter ß 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.gaitpost.2009.02.013
ment artefact could mean that repeatability would vary under different phases of the gait cycle. The aim of this study was therefore to compare foot kinematic data from this study and another centre as a preliminary examination of the model’s inter-centre repeatability and validity and then determine the repeatability of the foot model during various phases of the gait cycle. 2. Subjects and method The foot kinematics during gait of eight healthy children selected at random (three boys mean S.D., 12 3 years, range, 9–18 years) were tested on two separate occasions. The test and retest were scheduled to be within 1 month (23 23 days, range 2–58 days). The Oxford foot model was implemented according to Stebbins et al. [5]. Three trials of data were recorded for each foot of each subject. For the purposes of statistical analysis, data from the left foot for each trial were divided into the three ankle rockers as described by Perry [10]. The study complied with the principles laid down in the Declaration of Helsinki and was approved by the relevant local ethical committee (case number KF 07 317863). The subjects and their guardians gave their informed consent to the work.
D.J. Curtis et al. / Gait & Posture 30 (2009) 118–121
119
Fig. 1. Oxford foot model kinematic data from this study plotted against data from the published repeatability study by Stebbins et al. Continuous lines are plots from this study, broken lines are plots from the study by Stebbins et al. Bold lines are mean values, normal lines are 1S.D.
3. Results Foot kinematics for all subjects’ left foot obtained during the test visit were plotted against the data published in an earlier repeatability study of children at the Oxford Gait Laboratory [5] and are presented in Fig. 1. Mean gait velocities were (mean S.D.) 1.23 0.10 m/s in the test sessions for this study and 1.28 0.16 m/s for the Oxford study. Average walking speed for the healthy subjects was (mean S.D.) 1.23 0.10 m/s at the test visit and for the
retest visit 1.26 0.12 m/s. The difference was not significant (p = 0.06). Results for the selected parameters are presented in Table 1. Mean differences between the test–retest values in the selected parameters presented in Table 1 were small, varying from 0.38 to 1.98. None of the differences were significant. Relative reliability varied considerably with values for ICC3.1 as low as 0.09 for max. hindfoot eversion in first rocker and 0.96 for max. forefoot dorsiflexion in second rocker. Absolute reliability also varied considerably with TEM from 1.88 for max. forefoot dorsiflexion in
Table 1 Repeatability of foot kinematics in healthy subjects. Test
Mean S.D. Retest
Retest–test
t-Test
ICC3.1 (95% CI)
TEM (95% CI)
First rocker Max. hindfoot eversion Max. hindfoot plantarflexion
5.5 3.1 7.5 3.2
4.1 4.3 7.8 4.6
1.4 5.7 0.3 3.2
0.77 0.29
0.14 ( 0.74–0.58) 0.65 ( 0.28–0.92)
4.05 (3.00–6.26) 2.24 (1.65–3.46)
Second rocker Max. hindfoot dorsiflexion Max. forefoot dorsiflexion Max. hindfoot eversion Min. hindfoot eversion Mean forefoot supination Max. forefoot abduction
9.3 7.5 8.6 4.9 7.7 3.7 2.7 4.1 6.5 3.9 3.2 5.2
11.1 4.6 9.0 4.9 7.4 3.6 0.8 5.5 7.4 5.0 3.9 3.8
1.8 4.6 0.4 1.3 0.3 5.0 1.9 6.3 0.9 3.6 0.7 4.1
0.31 0.46 0.86 0.44 0.50 0.64
0.73 0.96 0.09 0.14 0.67 0.60
3.27 0.93 3.54 4.47 2.57 2.87
Third rocker Max. hindfoot plantarflexion
9.4 7.5
11.1 4.6
1.7 4.5
0.57
0.36 ( 0.40–0.83)
3.22 (2.38–4.98)
Swing phase Max. hindfoot dorsiflexion Max. forefoot dorsiflexion
4.3 5.0 3.7 4.6
5.4 3.6 2.4 5.6
1.1 4.8 1.3 4.1
0.53 0.40
0.39 ( 0.37–0.84) 0.69 (0.04–0.93)
3.41 (2.52–5.27) 2.88 (2.13–4.45)
(0.12–0.94) (0.83–0.99) ( 0.62–0.71) ( 0.58–0.74) (0.01–0.92) ( 0.11–0.91)
(2.42–5.07) (0.68–1.43) (2.61–5.47) (3.30–6.92) (1.90–3.97) (2.12–4.44)
Test/retest data are mean in degrees S.D. unless otherwise stated. S.D. = standard deviation, t-test = paired t-test, ICC3.1 = intraclass correlation coefficient, TEM = typical error of measurement ((S.D.(Retest–Test))/H2), 95% CI = 95% confidence interval (lower limit–upper limit). n = 8 (8 participants, 8 left feet).
D.J. Curtis et al. / Gait & Posture 30 (2009) 118–121
120
Table 2 Variation in absolute reliability of the Oxford foot model during stance and swing phase in healthy subjects. Segment
Typical error of measurement in degrees Stance phase rocker
Swing
First
Second
Third
Max. forefoot dorsiflexion Min. forefoot dorsiflexion Mean. forefoot dorsiflexion Max. forefoot adduction Min. forefoot adduction Mean forefoot adduction Max. forefoot supination Min. forefoot supination Mean forefoot supination Max. hindfoot dorsiflexion Min. hindfoot dorsiflexion Mean hindfoot dorsiflexion Max. hindfoot int. rotation Min. hindfoot int. rotation Mean hindfoot int. rotation Max. hindfoot inversion Min. hindfoot inversion Mean hindfoot inversion
2.01 1.72 1.89 3.05 2.65 2.85 2.29 2.24 2.22 3.50 3.18 3.29 8.56 8.33 8.42 3.88 4.05 3.95
0.93 2.39 1.79 2.78 2.87 2.84 2.64 2.58 2.57 3.27 3.76 3.42 6.54 7.02 6.53 4.47 3.54 3.74
1.37 2.47 1.39 3.47 3.22 3.45 2.17 2.45 2.23 3.22 4.18 3.43 6.12 7.00 6.55 3.50 3.77 3.62
2.88 – 1.74 – – – – – – 3.40 – 3.68 – – – – – –
Mean (range)
3.78 (1.72–8.56)
3.54 (0.93–7.02)
3.53 (1.37–7.00)
2.93 (1.74–3.68)
Comparison of foot kinematics from this study and the previously published repeatability study in children [5] suggests a good inter-centre repeatability in the sagittal plane but would indicate the need for further studies to determine the inter-centre repeatability and validity of this model especially for the heel segment in the frontal and transverse planes.
second rocker to 4.58 for minimum hindfoot eversion in second rocker. Absolute repeatability was best in the sagittal plane, followed by the frontal plane (inversion/eversion and supination/pronation). The poorest repeatability was in the transverse plane (rotation and abduction/adduction), especially for hindfoot rotation. Values for the typical errors of measurement are presented in Table 2. Analysis of both left and right feet produced very similar results for relative and absolute repeatability, but it was considered correct [11,12] to report results for just one foot for each child.
We would like to thank Thomas Bandholm PhD stud., MSc PT, for providing statistical advice.
4. Discussion
Conflict of interest statement
There was a considerable variation in relative and absolute repeatability between segments and planes. Repeatability was greatest in the sagittal plane, followed by the frontal plane and lastly the transverse plane. This is consistent with earlier published reliability studies of the model [5,9]. There appeared to be particularly poor results in the hindfoot rotation where the standard deviation of the difference between test–retest values was between 9.48 and 10.88. The plots in the sagittal plane for the forefoot and hindfoot reflect kinematic patterns from other studies [1,5,9,13,14]. The plots from this study are similar to the Stebbins et al. study in both form and range, but are vertically shifted for the hindfoot in the transverse plane and hindfoot and forefoot in the frontal plane. The difference of approximately 48 in the frontal plane for the forefoot appears to be due to a similar but opposite shift in the plot for the frontal plane of the hindfoot. Similar problems with defining hindfoot neutral is apparent in other studies [9,13–15] with differing peak values for hindfoot inversion/eversion in gait but a similar range of motion. The poor repeatability for the hindfoot in the frontal and transverse planes in this study indicates the same difficulty in defining and identifying the neutral position of the hindfoot. Repeatability for a given intersegmental angle appeared to be consistent throughout the gait cycle with no great differences between the three ankle rockers. It would therefore appear that the Oxford foot model’s repeatability is consistent throughout the gait cycle.
None of the authors have any financial and personal relationships with other people or organizations that could inappropriately influence (bias) their work.
Acknowledgements
References [1] Kidder SM, Abuzzahab Jr FS, Harris GF, Johnson JE. A system for the analysis of foot and ankle kinematics during gait. IEEE Trans Rehabil Eng 1996;4: 25–32. [2] Leardini A, Benedetti MG, Catani F, Simoncini L, Giannini S. An anatomically based protocol for the description of foot segment kinematics during gait. Clin Biomech (Bristol Avon) 1999;14:528–36. [3] Liu W, Siegler S, Hillstrom H, Whitney K. Three-dimensional, six-degrees-offreedom kinematics of the human hindfoot during the stance phase of level walking. Hum Mov Sci 1997;16:283–98. [4] Simon J, Doederlein L, McIntosh AS, Metaxio D, Bock HG, Wolf SI. The Heidelberg foot measurement method: development, description and assessment. Gait Posture 2006;23:411–24. [5] Stebbins J, Harrington M, Thompson N, Zavatsky A, Theologis T. Repeatability of a model for measuring multi-segment foot kinematics in children. Gait Posture 2006;23:401–10. [6] Leardini A, Benedetti MG, Berti L, Bettinelli D, Nativo R, Giannini S. Rear-foot, mid-foot and fore-foot motion during the stance phase of gait. Gait Posture 2007;25:453–62. [7] Cornwall MW, McPoil TG. Three-dimensional movement of the foot during the stance phase of walking. J Am Podiatr Med Assoc 1999;89:56–66. [8] MacWilliams BA, Cowley M, Nicholson DE. Foot kinematics and kinetics during adolescent gait. Gait Posture 2003;17:214–24. [9] Carson MC, Harrington ME, Thompson N, O’Connor JJ, Theologis TN. Kinematic analysis of a multi-segment foot model for research and clinical applications: a repeatability analysis. J Biomech 2001;34:1299–307. [10] Perry J. Gait analysis: normal and pathological function. Thorofare, NJ: SLACK Incorporated; 1992.
D.J. Curtis et al. / Gait & Posture 30 (2009) 118–121 [11] Menz HB. Analysis of paired data in physical therapy research: time to stop double-dipping? J Orthop Sports Phys Ther 2005;35:477–8. [12] Menz HB. Two feet, or one person? Problems associated with statistical analysis of paired data in foot and ankle medicine. The Foot 2004;14: 2–5. [13] Rattanaprasert U, Smith R, Sullivan M, Gilleard W. Three-dimensional kinematics of the forefoot, rearfoot, and leg without the function of tibialis
121
posterior in comparison with normals during stance phase of walking. Clin Biomech (Bristol Avon) 1999;14:14–23. [14] Hunt AE, Smith RM, Torode M, Keenan AM. Inter-segment foot motion and ground reaction forces over the stance phase of walking. Clin Biomech (Bristol Avon) 2001;16:592–600. [15] Torburn L, Perry J, Gronley JK. Assessment of rearfoot motion: passive positioning, one-legged standing, gait. Foot Ankle Int 1998;19:688–93.
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
Short communication
Intra-rater repeatability of the Oxford foot model in healthy children in different stages of the foot roll over process during gait D.J. Curtis a,b,*, J. Bencke a, J.A. Stebbins c, B. Stansfield d a
Gait Analysis Laboratory, Dept of Orthopedic Surgery, Hvidovre University Hospital, Kettegaard Alle´ 30, DK-2650 Hvidovre, Denmark Dept of Physiotherapy, Hvidovre University Hospital, Kettegaard Alle´ 30, DK-2650 Hvidovre, Denmark c Oxford Gait Laboratory, Nuffield Orthopaedic Centre, Windmill Road, Headington, Oxford OX3 7LD, UK d School of Health and Social Care, Glasgow Caledonian University, Glasgow, UK b
A R T I C L E I N F O
A B S T R A C T
Article history: Received 8 August 2008 Received in revised form 13 February 2009 Accepted 18 February 2009
Background: The repeatability of the Oxford foot model has been reported, but possible variations in the repeatability during the foot roll over process have not been examined. The aim of this study was to determine the relative and absolute repeatability of the model for each stage of the foot roll over process during gait and to compare foot kinematic data from this study with that from another centre as a preliminary examination of the model’s inter-centre repeatability and validity. Method: Eight healthy children were tested twice at the gait laboratory. Foot kinematics from this study were plotted against those from an earlier repeatability study and repeatability statistics calculated for the three rockers of stance phase and swing phase. Results: Foot kinematics from this study and an earlier repeatability study produced similar kinematic patterns and joint angle ranges, but there were offsets in the absolute joint angles in the frontal and transverse planes. Relative and absolute repeatability were best in the sagittal plane (flexion/extension) with the poorest repeatability in the transverse plane (rotation and abduction/adduction). There was little difference in repeatability between the three rockers. Typical error of measurement varied between planes and segments from 0.98 for maximum forefoot dorsiflexion in second rocker to 8.68 for maximum hindfoot internal rotation in first rocker. Discussion: Repeatability varied markedly between planes and segments but was consistent throughout the gait cycle. Further studies are needed to determine the inter-centre repeatability and validity of the model. ß 2009 Elsevier B.V. All rights reserved.
Keywords: Foot Kinematics Repeatability Instrumented gait analysis Oxford foot model
1. Introduction A number of models have been suggested to allow a more detailed analysis of foot kinematics [1–8]. The Oxford foot model appears from two published studies [5,9] to have a good repeatability in healthy subjects but there are no published studies examining the inter-centre repeatability or validity of the model. As this model is used clinically to determine the effect of an intervention on foot kinematics in a given phase of the gait cycle, it was felt that the repeatability of the model should be examined for each of these phases as it was possible that factors such as mechanical loading (e.g. heel pad deformation) and skin move-
* Corresponding author at: Gait Analysis Laboratory, Dept of Orthopedic Surgery, Hvidovre University Hospital, Kettegaard Alle´ 30, DK-2650 Hvidovre, Denmark. Tel.: +45 3632 6248. E-mail address: [email protected] (D.J. Curtis). 0966-6362/$ – see front matter ß 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.gaitpost.2009.02.013
ment artefact could mean that repeatability would vary under different phases of the gait cycle. The aim of this study was therefore to compare foot kinematic data from this study and another centre as a preliminary examination of the model’s inter-centre repeatability and validity and then determine the repeatability of the foot model during various phases of the gait cycle. 2. Subjects and method The foot kinematics during gait of eight healthy children selected at random (three boys mean S.D., 12 3 years, range, 9–18 years) were tested on two separate occasions. The test and retest were scheduled to be within 1 month (23 23 days, range 2–58 days). The Oxford foot model was implemented according to Stebbins et al. [5]. Three trials of data were recorded for each foot of each subject. For the purposes of statistical analysis, data from the left foot for each trial were divided into the three ankle rockers as described by Perry [10]. The study complied with the principles laid down in the Declaration of Helsinki and was approved by the relevant local ethical committee (case number KF 07 317863). The subjects and their guardians gave their informed consent to the work.
D.J. Curtis et al. / Gait & Posture 30 (2009) 118–121
119
Fig. 1. Oxford foot model kinematic data from this study plotted against data from the published repeatability study by Stebbins et al. Continuous lines are plots from this study, broken lines are plots from the study by Stebbins et al. Bold lines are mean values, normal lines are 1S.D.
3. Results Foot kinematics for all subjects’ left foot obtained during the test visit were plotted against the data published in an earlier repeatability study of children at the Oxford Gait Laboratory [5] and are presented in Fig. 1. Mean gait velocities were (mean S.D.) 1.23 0.10 m/s in the test sessions for this study and 1.28 0.16 m/s for the Oxford study. Average walking speed for the healthy subjects was (mean S.D.) 1.23 0.10 m/s at the test visit and for the
retest visit 1.26 0.12 m/s. The difference was not significant (p = 0.06). Results for the selected parameters are presented in Table 1. Mean differences between the test–retest values in the selected parameters presented in Table 1 were small, varying from 0.38 to 1.98. None of the differences were significant. Relative reliability varied considerably with values for ICC3.1 as low as 0.09 for max. hindfoot eversion in first rocker and 0.96 for max. forefoot dorsiflexion in second rocker. Absolute reliability also varied considerably with TEM from 1.88 for max. forefoot dorsiflexion in
Table 1 Repeatability of foot kinematics in healthy subjects. Test
Mean S.D. Retest
Retest–test
t-Test
ICC3.1 (95% CI)
TEM (95% CI)
First rocker Max. hindfoot eversion Max. hindfoot plantarflexion
5.5 3.1 7.5 3.2
4.1 4.3 7.8 4.6
1.4 5.7 0.3 3.2
0.77 0.29
0.14 ( 0.74–0.58) 0.65 ( 0.28–0.92)
4.05 (3.00–6.26) 2.24 (1.65–3.46)
Second rocker Max. hindfoot dorsiflexion Max. forefoot dorsiflexion Max. hindfoot eversion Min. hindfoot eversion Mean forefoot supination Max. forefoot abduction
9.3 7.5 8.6 4.9 7.7 3.7 2.7 4.1 6.5 3.9 3.2 5.2
11.1 4.6 9.0 4.9 7.4 3.6 0.8 5.5 7.4 5.0 3.9 3.8
1.8 4.6 0.4 1.3 0.3 5.0 1.9 6.3 0.9 3.6 0.7 4.1
0.31 0.46 0.86 0.44 0.50 0.64
0.73 0.96 0.09 0.14 0.67 0.60
3.27 0.93 3.54 4.47 2.57 2.87
Third rocker Max. hindfoot plantarflexion
9.4 7.5
11.1 4.6
1.7 4.5
0.57
0.36 ( 0.40–0.83)
3.22 (2.38–4.98)
Swing phase Max. hindfoot dorsiflexion Max. forefoot dorsiflexion
4.3 5.0 3.7 4.6
5.4 3.6 2.4 5.6
1.1 4.8 1.3 4.1
0.53 0.40
0.39 ( 0.37–0.84) 0.69 (0.04–0.93)
3.41 (2.52–5.27) 2.88 (2.13–4.45)
(0.12–0.94) (0.83–0.99) ( 0.62–0.71) ( 0.58–0.74) (0.01–0.92) ( 0.11–0.91)
(2.42–5.07) (0.68–1.43) (2.61–5.47) (3.30–6.92) (1.90–3.97) (2.12–4.44)
Test/retest data are mean in degrees S.D. unless otherwise stated. S.D. = standard deviation, t-test = paired t-test, ICC3.1 = intraclass correlation coefficient, TEM = typical error of measurement ((S.D.(Retest–Test))/H2), 95% CI = 95% confidence interval (lower limit–upper limit). n = 8 (8 participants, 8 left feet).
D.J. Curtis et al. / Gait & Posture 30 (2009) 118–121
120
Table 2 Variation in absolute reliability of the Oxford foot model during stance and swing phase in healthy subjects. Segment
Typical error of measurement in degrees Stance phase rocker
Swing
First
Second
Third
Max. forefoot dorsiflexion Min. forefoot dorsiflexion Mean. forefoot dorsiflexion Max. forefoot adduction Min. forefoot adduction Mean forefoot adduction Max. forefoot supination Min. forefoot supination Mean forefoot supination Max. hindfoot dorsiflexion Min. hindfoot dorsiflexion Mean hindfoot dorsiflexion Max. hindfoot int. rotation Min. hindfoot int. rotation Mean hindfoot int. rotation Max. hindfoot inversion Min. hindfoot inversion Mean hindfoot inversion
2.01 1.72 1.89 3.05 2.65 2.85 2.29 2.24 2.22 3.50 3.18 3.29 8.56 8.33 8.42 3.88 4.05 3.95
0.93 2.39 1.79 2.78 2.87 2.84 2.64 2.58 2.57 3.27 3.76 3.42 6.54 7.02 6.53 4.47 3.54 3.74
1.37 2.47 1.39 3.47 3.22 3.45 2.17 2.45 2.23 3.22 4.18 3.43 6.12 7.00 6.55 3.50 3.77 3.62
2.88 – 1.74 – – – – – – 3.40 – 3.68 – – – – – –
Mean (range)
3.78 (1.72–8.56)
3.54 (0.93–7.02)
3.53 (1.37–7.00)
2.93 (1.74–3.68)
Comparison of foot kinematics from this study and the previously published repeatability study in children [5] suggests a good inter-centre repeatability in the sagittal plane but would indicate the need for further studies to determine the inter-centre repeatability and validity of this model especially for the heel segment in the frontal and transverse planes.
second rocker to 4.58 for minimum hindfoot eversion in second rocker. Absolute repeatability was best in the sagittal plane, followed by the frontal plane (inversion/eversion and supination/pronation). The poorest repeatability was in the transverse plane (rotation and abduction/adduction), especially for hindfoot rotation. Values for the typical errors of measurement are presented in Table 2. Analysis of both left and right feet produced very similar results for relative and absolute repeatability, but it was considered correct [11,12] to report results for just one foot for each child.
We would like to thank Thomas Bandholm PhD stud., MSc PT, for providing statistical advice.
4. Discussion
Conflict of interest statement
There was a considerable variation in relative and absolute repeatability between segments and planes. Repeatability was greatest in the sagittal plane, followed by the frontal plane and lastly the transverse plane. This is consistent with earlier published reliability studies of the model [5,9]. There appeared to be particularly poor results in the hindfoot rotation where the standard deviation of the difference between test–retest values was between 9.48 and 10.88. The plots in the sagittal plane for the forefoot and hindfoot reflect kinematic patterns from other studies [1,5,9,13,14]. The plots from this study are similar to the Stebbins et al. study in both form and range, but are vertically shifted for the hindfoot in the transverse plane and hindfoot and forefoot in the frontal plane. The difference of approximately 48 in the frontal plane for the forefoot appears to be due to a similar but opposite shift in the plot for the frontal plane of the hindfoot. Similar problems with defining hindfoot neutral is apparent in other studies [9,13–15] with differing peak values for hindfoot inversion/eversion in gait but a similar range of motion. The poor repeatability for the hindfoot in the frontal and transverse planes in this study indicates the same difficulty in defining and identifying the neutral position of the hindfoot. Repeatability for a given intersegmental angle appeared to be consistent throughout the gait cycle with no great differences between the three ankle rockers. It would therefore appear that the Oxford foot model’s repeatability is consistent throughout the gait cycle.
None of the authors have any financial and personal relationships with other people or organizations that could inappropriately influence (bias) their work.
Acknowledgements
References [1] Kidder SM, Abuzzahab Jr FS, Harris GF, Johnson JE. A system for the analysis of foot and ankle kinematics during gait. IEEE Trans Rehabil Eng 1996;4: 25–32. [2] Leardini A, Benedetti MG, Catani F, Simoncini L, Giannini S. An anatomically based protocol for the description of foot segment kinematics during gait. Clin Biomech (Bristol Avon) 1999;14:528–36. [3] Liu W, Siegler S, Hillstrom H, Whitney K. Three-dimensional, six-degrees-offreedom kinematics of the human hindfoot during the stance phase of level walking. Hum Mov Sci 1997;16:283–98. [4] Simon J, Doederlein L, McIntosh AS, Metaxio D, Bock HG, Wolf SI. The Heidelberg foot measurement method: development, description and assessment. Gait Posture 2006;23:411–24. [5] Stebbins J, Harrington M, Thompson N, Zavatsky A, Theologis T. Repeatability of a model for measuring multi-segment foot kinematics in children. Gait Posture 2006;23:401–10. [6] Leardini A, Benedetti MG, Berti L, Bettinelli D, Nativo R, Giannini S. Rear-foot, mid-foot and fore-foot motion during the stance phase of gait. Gait Posture 2007;25:453–62. [7] Cornwall MW, McPoil TG. Three-dimensional movement of the foot during the stance phase of walking. J Am Podiatr Med Assoc 1999;89:56–66. [8] MacWilliams BA, Cowley M, Nicholson DE. Foot kinematics and kinetics during adolescent gait. Gait Posture 2003;17:214–24. [9] Carson MC, Harrington ME, Thompson N, O’Connor JJ, Theologis TN. Kinematic analysis of a multi-segment foot model for research and clinical applications: a repeatability analysis. J Biomech 2001;34:1299–307. [10] Perry J. Gait analysis: normal and pathological function. Thorofare, NJ: SLACK Incorporated; 1992.
D.J. Curtis et al. / Gait & Posture 30 (2009) 118–121 [11] Menz HB. Analysis of paired data in physical therapy research: time to stop double-dipping? J Orthop Sports Phys Ther 2005;35:477–8. [12] Menz HB. Two feet, or one person? Problems associated with statistical analysis of paired data in foot and ankle medicine. The Foot 2004;14: 2–5. [13] Rattanaprasert U, Smith R, Sullivan M, Gilleard W. Three-dimensional kinematics of the forefoot, rearfoot, and leg without the function of tibialis
121
posterior in comparison with normals during stance phase of walking. Clin Biomech (Bristol Avon) 1999;14:14–23. [14] Hunt AE, Smith RM, Torode M, Keenan AM. Inter-segment foot motion and ground reaction forces over the stance phase of walking. Clin Biomech (Bristol Avon) 2001;16:592–600. [15] Torburn L, Perry J, Gronley JK. Assessment of rearfoot motion: passive positioning, one-legged standing, gait. Foot Ankle Int 1998;19:688–93.