Elsevier

Manual Therapy

Volume 17, Issue 5, October 2012, Pages 422-426
Manual Therapy

Original article
Assessment of spinal mobility in ankylosing spondylitis using a video-based motion capture system

https://doi.org/10.1016/j.math.2012.03.011Get rights and content

Abstract

This paper describes the use of a video-based motion capture system to assess spinal mobility in patients with ankylosing spondylitis (AS). The aim of the study is to assess reliability of the system comparing it with conventional metrology in order to define and analyze new measurements that reflect better spinal mobility. A motion capture system (UCOTrack) was used to measure spinal mobility in forty AS patients and twenty healthy subjects with a marker set defining 33 3D measurements, some already being used in conventional metrology. Radiographic studies were scored using the modified Stoke Ankylosing Spondylitis Spine Score index (mSASSS). Test–retest reliability studies were performed on the same day and over a two-week period. Motion capture shows very high reliability with Intraclass Correlation Coefficient values ranging from 0.89 to 0.99, low Standard Error of the Measurement (0.37–1.33 cm and 1.58°–6.54°), correlating very well with the Bath Ankylosing Spondylitis Metrology Index (BASMI) (p < 0.001) and, in some individual measures (cervical flexion, cervical lateral flexion, back inclination, shoulder–hip angle and spinal rotation), with mSASSS (p < 0.01). mSASSS also added significantly to the variance in multivariate linear regression analysis to certain measures (back inclination, cervical flexion and cervical lateral flexion). Quantitative results obtained with motion capture system using the protocol defined show to be highly reliable in patients with AS. This technique could be a useful tool for assessing the outcome of the disease and for monitoring the evolution of spinal mobility in AS patients.

Introduction

Ankylosing Spondylitis (AS) is a chronic rheumatic disease that mainly affects the spine and in which the inflammatory process induces structural damage characterized by the fusion of joints as well as intervertebral space (Wanders et al., 2005). Loss of spinal mobility is a major feature of the disease and it is one of the criteria that the patient must fulfill to be diagnosed with AS, according to the New York modified diagnostic criteria (van der Linden et al., 1984). Metrologic assessment of spinal mobility has been widely used in the diagnosis, follow-up, as well as responsiveness to treatment in patients with AS (Viitanen et al., 2000).

ASAS (Assessment in AS working group) recommends the use of the Bath Ankylosing Spondylitis Metrology Index (BASMI) (Jenkinson et al., 1994), which includes five measurements: the modified Schober test, spinal lateral flexion, intermalleolar distance, tragus to wall distance and cervical rotation. BASMI is calculated based on certain measurements obtained using elementary instrumentation such as tape measures or goniometer. Structural damage in AS may be measured with different scoring methods on radiographs of the spine such as: the Bath Ankylosing Spondylitis Radiology Index (BASRI) (MacKay et al., 1998), the Stoke Ankylosing Spondylitis Spine Score (SASSS) (Averns et al., 1996), and a modification of the SASSS (mSASSS) (Creemers et al., 2005). The latter index scores cervical and lumbar spine according to erosions, syndesmophytes and bone bridges. mSASSS was demonstrated in clinical trials to be the most appropriate method to score radiographic progression in AS patients (Wanders et al., 2004).

Usually BASMI is used for the assessment of mobility and mSASSS for structural damage. In assessing disease-modifying potential of newly introduced highly cost biological therapies in the treatment of AS, it is essential to demonstrate the improvement of spinal mobility. So, more precise and reliable measurement tools are needed to correctly assess therapeutic results (Fleurence and Spackman, 2006).

Automated motion capture is a recently-developed technology that allows human movement to be measured in an objective and quantitative manner with high levels of precision. This technology has been used successfully in sports, clinical medicine, industry, ergonomics, animation and virtual reality, among others (Castro et al., 2006).

There are two main objectives in this study: (1) to evaluate the use of a video-based motion capture system to assess spinal mobility in patients with AS by using conventional metrological measurements obtained with our motion system and (2) to propose new 3D measurements that could better reflect spinal mobility. Finally construct validity studies were performed for both objectives; mobility results were correlated with conventional metrology (BASMI) and radiographic score (mSASSS) and multivariate linear regression analyzing structural damage were also undertaken.

Section snippets

Patients

Forty AS patients according to New York modified criteria (van der Linden et al., 1984) (36 males and 4 females) and twenty healthy subjects (10 males and 10 females) as control group who were willing to participate in the study, were consecutively included. AS patients had at least five years of disease duration with varying degrees of limited spinal mobility as measured with BASMI. To analyze the data of BASMI we divided the patients into 3 groups of affectation: low, medium and high degree

Descriptive data

The group of patients with AS had the following characteristics: age at diagnosis 25.8 ± 7.9, evolution of disease 14.5 ± 10.84 years, BASMI 3.37 ± 2.46 and mSASSS 31.4 ± 24.1. Thirty three (82%) of these patients were human leukocyte antigen (HLA) B27 positive. The descriptive statistics of the ROM measurements are shown in Table 1. For each measurement mean and standard deviation (SD) values are shown in four columns: one for control group and the other three for the different groups of

Discussion

The assessment of spinal mobility in AS patients is very important as it indicates the structural damage. For this reason, mobility evaluation is included in all the recommendations of disease assessment and follow-up. In this paper we propose a video-based motion capture system to solve the accuracy and reliability problems of conventional metrology involved in assessing mobility in AS patients. The precision and accuracy of the system have already been demonstrated in previous studies (Castro

Conclusion

In this study, results obtained show that the use of the motion capture technologies produce precise and reliable quantitative results for the measurements that are traditionally included in the assessment of AS. In addition, we have defined new measurements that appear to show better the level of affectation in AS patients. Thus, the use of the motion capture systems to obtain these measurements can be of great aid in assessing and monitoring AS.

Acknowledgments

This study has been financed by Ministerio de Ciencia e Innovacion of Spain (PI10/01524) and by Consejeria de Salud de la Junta de Andalucia (PI0243/2009).

The authors thank to AS Patients’ Association of Cordoba (ACEADE) for their collaboration.

References (18)

  • J.L. Castro et al.

    Design and evaluation of a new three-dimensional motion capture system based on video

    Gait and Posture

    (2006)
  • R. Almodóvar et al.

    Relationship between spinal mobility and disease activity, function, quality of life and radiology. A cross-sectional Spanish registry of spondyloarthropathies (REGISPONSER)

    Clinical and Experimental Rheumatology

    (2009)
  • G. Atkinson et al.

    Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine

    Sports Medicine (Auckland, NZ)

    (1998)
  • H.L. Averns et al.

    Radiological outcome in ankylosing spondylitis: use of the stoke ankylosing spondylitis spine score (SASSS)

    British Journal of Rheumatology

    (1996)
  • J. Chen et al.

    Meta-analysis of normative cervical motion

    Spine

    (1999)
  • E. Collantes et al.

    Three-dimensional measurement of spinal mobility in ankylosing spondylitis using a motion capture system: reliability and validation. Preliminary results

    Annals of the Rheumatic Diseases

    (2008)
  • M.C. Creemers et al.

    Assessment of outcome in ankylosing spondylitis: an extended radiographic scoring system

    Annals of the Rheumatic Diseases

    (2005)
  • R. Fleurence et al.

    Cost-effectiveness of biologic agents for treatment of autoimmune disorders: structured review of the literature

    The Journal of Rheumatology

    (2006)
  • K.L. Haywood et al.

    Spinal mobility in ankylosing spondylitis: reliability, validity and responsiveness

    Rheumatology (Oxford)

    (2004)
There are more references available in the full text version of this article.

Cited by (0)

View full text