VERTEBRAL METRICS: APPLICATION OF A INSTRUMENT

TO EVALUATE THE SPINAL COLUMN IN PREGNANT

WOMEN

Cláudia Quaresma

1,2

, Miguel Fonseca

, Mário Forjaz Secca

1,4

, J. Goyri O’Neill

1,5

and J. Branco

5,6

CEFITEC, Dep. de Fisica, Faculdade de Ciências e Tecnologia, UNL, Quinta da Torre, P-2829-516, Caparica, Portugal

Departamento de Saúde, Instituto Politécnico de Beja, P-7800-111, Beja, Portugal

CMA, Departamento de Matemática Faculdade de Ciências e Tecnologia, UNL,

Quinta da Torre, P-2829-516, Caparica, Portugal

Ressonância Magnética de Caselas, Lisboa, Portugal

Faculdade de Ciências Médicas, UNL, Quinta da Torre, P-2829-516, Lisboa, Portugal

Maternidade Dr. Alfredo da Costa, Lisboa, Portugal

Keywords: Biomechanics, Spinal Column, Non-invasive instrument, Evaluation, Standing position, Pregnant women.

Abstract: The published literature about the biomechanical alterations of the spinal column during pregnancy is scarce

and disperses, being more qualitative and limited to partial analysis of the spinal column. The main

justification for a global approach to be neglected could be related to the inexistence of a non-invasive

instrument that evaluates the spinal column in an objective and complete way. Thus, in order to fill this gap,

we built Vertebral Metrics – a device that allows the identification of the 3D position of the vertex of each

of the spinal processes, from the first cervical vertebra to the first sacral vertebra and calculate the amplitude

of the angles of curvature of the spinal column in the standing position. The present work has the objective

of presenting the first application of this equipment to 49 pregnant women at four different moments of

pregnancy (12, 20, 32 e 37 weeks of gestation). Analysing the results we can conclude that Vertebral

Metrics – is an innovative instrument in the global evaluation of the spinal column in a standing position,

allowing a quantitative analysis of its shape and temporal variations.

1 INTRODUCTION

In modern society, back pain is a problem relevant

for the population in general and for pregnant

women on particular, being a common symptom and

frequently referred to in pregnancies without any

pathology associated Studies indicate that 35 to 76%

of pregnant women experience back pain during

gestation. Although many women feel back pain

during pregnancy, this has not been considered an

important public health problem, not with standing

the social and economic impact that this situation

causes in the labour market if we take into account

the levels of absenteeism resulting from that (Noren

et al., 1994).

The majority of researchers attributes the

etiology of back pain to the biomechanical

alterations of the spinal columns during the

pregnancy period, however, an in depth study of this

analysis has been blocked by the fact that the

encompassing analytical processes are of an invasive

nature and, as such, cannot be applied to pregnant

women. On the other hand, the non-invasive means

of diagnostic only allow partial analyses of the

spinal column, not presenting a global vision.

The published literature on this matter is scarce

and disperse, being more qualitative and limited to

partial analyses of the spinal column. The main

justification for a global approach to be neglected

could be related to the inexistence of a non-invasive

instrument that evaluates the spinal column in an

objective and complete way. Thus, and to achieve

the main objective of the present study, we built

Vertebral Metrics – device that allows the

identification of the 3D positions of the vertex of

each of the spinous processes, from the first cervical

vertebra to first sacral vertebra, in the standing

position (Quaresma et al., 2009 a, b).

We stress that the quantitative characterization

of the biomechanical alterations of the spinal column

is fundamental to delineate prevention and

376

Quaresma C., Fonseca M., Forjaz Secca M., Goyri O’Neill J. and Branco J..

VERTEBRAL METRICS: APPLICATION OF A INSTRUMENT TO EVALUATE THE SPINAL COLUMN IN PREGNANT WOMEN.

DOI: 10.5220/0003798303760379

In Proceedings of the International Conference on Biomedical Electronics and Devices (BIODEVICES-2012), pages 376-379

ISBN: 978-989-8425-91-1

 2012 SCITEPRESS (Science and Technology Publications, Lda.)

intervention strategies in this domain.

Vertebral Metrics (Figure 1) is composed of two

parts: one we call Body and another we call Support

(Quaresma et al., 2009 a, b).

Figure 1: Vertebral Metrics.

The Support is composed of a central piece that

serves as the support for the vertical piece of the

Body of the instrument, having as an aid to stability

two lateral vertical pieces, two lateral oblique pieces

and one base where the person to evaluated stands

(Quaresma et al., 2009 a, b).

In turn, the Body is composed of a vertical piece

and 18 horizontal pieces that we call 2D Positioners.

The vertical piece of the Body, fits in the Support,

and is composed of a fixed rack and a square base

profile, four cylindrical solid bars, a graduated ruler

and two support plates in the extremities of all these

structures (Quaresma et al., 2009 a, b).

Each 2D Positioner is adjustable in a way to

identify the x, y and z position of each vertex of the

spinous processes, from the first cervical vertebra to

first sacral vertebra (Quaresma et al., 2010 a, b).

In the scope of the present work we also

developed a mathematical model of the spinal

column that aims to estimate the amplitude of the

angles of curvature the data collected by Vertebral

Metrics (x, y and z position of the spinous

processes).

The model is composed of an Hermitian cubic

spline (Sulij e Mayers, 2003).

2 METHODOLOGY

Vertebral Metrics was applied to pregnant women,

without pathology associated, in four different

moments of pregnancy without associated, in four

moments of pregnancy (12, 20, 32 and 37 weeks of

gestation).

Faced with the existence of certain variables

whose identification or control was not always

guaranteed, there was the need of establishing some

rules with the purpose of diminishing the effects of

the influence or bias of the results obtained. Thus we

defined the following principles:

• data collection should be performed always by

the same observer;

• random sampling method;

• evaluation to be performed on the same period of

the day for each of the pregnant women;

• identification of the position of Vertebral Metrics

through the use of markers on the floor;

• position of the feet always the same in all the

moments of the evaluation, when applying

Vertebral Metrics.

3 CHARACTERIZATION OF THE

SAMPLE

The sample is composed of 49 women aged between

19 and 42 years, where the mean is 30 years. The

prevalent nationality of the sample is Portuguese

(73,5%) being almost all women Caucasian (91,8%).

The majority of the women were married or lived

maritally (79,6%) and has a family aggregate of two

people (65,3%). Relative the education, the majority

was educated to a level higher than the 3

cycle of

basic education (40,8% secondary education e

40,8% higher education). Regarding the exercise of

the profession being standing or seated, about half

worked mainly standing (51%) and 30,6% mainly

seated.

4 RESULTS

The analysis of angles of the lumbar lordosis, dorsal

kyphosis and cervical lordosis revealed that the

average of the angles, as well as the respective

dispersion, varies throughout pregnancy (Figure 2).

Observation of data indicates, as well, that the

behaviour pattern of the amplitude of the angle of

each of the curvatures is distinct.

Figure 2: Averages and 95% confidence intervals for the

angles of the Cervical Lordosis, Dorsal Kyphosis e

Lumbar Lordosis at the 12

, 20

, 32

and 37

week of

gestation.

VERTEBRAL METRICS: APPLICATION OF A INSTRUMENT TO EVALUATE THE SPINAL COLUMN IN

PREGNANT WOMEN

377

We observed that cervical lordosis decreases, on

average, only 0,6° between the 12th and the 20

week of gestation, while from the 20

to the 32

week it increases, on average, 2,2° and on the 37

week it decreases again, on average, 1,6°.

In relation to dorsal kyphosis, we observed that

the angle at the 20

week of gestation begins

increasing, on average, 1,3°, at the 32

week it

decreased, on average, 3,5° and at the 37

week

continues to decrease with a smaller amplitude, on

average, only 0,1°.

Relative to lumbar lordosis, we observed that the

angle decreases at the 20

week, on average 4,6°, at

the 32

week increases, on average, 4,3°, and at the

week we found that it continues to increase

(2,1°).

We concluded that, between the 12

and the 37

week of gestation, the angle of lumbar lordosis and

dorsal kyphosis, on average, increases 1,8° and 2,4°,

respectively. On the other hand, the angle of the

cervical lordosis, on average, decreases only 0,1°.

Applying the linear regression correlation

significance test from one moment of evaluation to

the next, we noted that there are no significant

differences in the angle of curvature throughout

pregnancy, except for lumbar lordosis between the

and the 20

week of gestation (p<0,05).

During data collection, and only through clinical

observation, we assumed that the difference of the

angles between two successive moments could be

different throughout pregnancy. Due to the absence

of studies in this domain we decided to compare the

difference of the angles between two consecutive

moments of evaluation, with the homologous

difference between the two moments of evaluation

immediatly after. We oberved that there is a negative

correlation (p<0,001).

We conclude that when the angle of curvature

increases between the 12

and 20

weeks of

gestation, it diminishes between the 20

and 32

weeks and increases again between the 32

and 37

weeks of gestation.

On the other hand, analysis of the data raised

doubt relative to the amplitude of the angles

throughout pregnancy.

To test this hypothesis, and taking into account

the angles registered in two consecutive moments,

using as reference the 12

week, two groups of

pregnant women were formed: one where the angle

increases between two consecutive moments;

another where the angle decreases between those

two moments.

We compared the angle of each of the curvatures

in the four moments of evaluation and we observed

that there are significant differences in the two

groups in the various moments, relative to all the

angles. We observed, for example, that the average

of the angle of lumbar lordosis at the 12

week is

the following:

• 36,9° (IC95% 27,0–46,8) – group of women

where the angle increases from the 12

to the

week

• 50,6° (IC95% 41,4–59,8) - group of women

where the angle decreases from the 12

to the

week

We conclude that, although there are no

significant differences in the angles of curvature

throughout pregnancy, we saw that those same

angles oscillate in a significant way throughout the

gestation period. That is, when they increase from

the 12

to the 32

week, they decrease from the 20

to the 32

and increase again from the 32

to the

week of gestation.

We also noted that the referred alteration in the

angle form the 12

to the 20

week behaves in the

opposite way taking into account the angle that each

pregnant woman presents on the 12

week. Thus, for

example, if the average value of the amplitude

identified in the first moment of evaluation is 50,8°,

we observe that that angle will decrease in the

following period, increasing again in the following

one.

5 CONCLUSIONS

With the building of Vertebral Metrics – innovative

instrument for a global evaluation of the spinal

column, we produced for the first time a systematic

and global study of the spinal column that

contemplates the characterization of the amplitude

of its angles of curvature.

In reality, the inexistence of studies that evaluate

simultaneously the angle of the three curvatures of

the spinal column at the same temporal period, limits

in a certain way the comparability with other

analyses, however it transforms this work in a

reference in the Health area. As far as we know this

is the first investigation that approaches in an

integrated way the spinal column in its totality. Lack

of consensus will probably be related to three crucial

variables:

• the small number of quantitative studies;

• the methodology applied in the data collection;

• the not very expressive number of pregnant

women involved in the majority of quantitative

studies.

BIODEVICES 2012 - International Conference on Biomedical Electronics and Devices

378

We highlight the fact that Vertebral Metrics

represents an innovation in the field of prevention

since it can be applied several consecutive times

without harming the person. On top of that it is not

expensive, easily transported and has few logistic

demands. All this makes it possible to be used in

different contexts like for instance the ambulatory:

public, private (health centres / clinics) and

hospitals.

ACKNOWLEDGEMENTS

C. Quaresma would like to acknowledge Fundação

CIência e Tecnologia (FCT) for the grant (SFRH /

BD / 44042 / 2008).

REFERENCES

Noren L, Ostgaard S, Nielsen T T, Ostgaard H C.

Reduction of sick leaves for lumbar back and posterior

pelvic pain in pregnancy. Spine 1994; 19 (8): 894-900.

Quaresma, C.; Forjaz Secca, M.; O’Neill, J.; Branco, J.,

2009a. Development a mechanical instrument to

evaluate biomechanically the spinal columnin

pregnant women. Proc. Internacional Conference

Biodevice, 310-113.

Quaresma, C.; João, F. Fonseca, M. Forjaz Secca, M.

Veloso, A.; O’Neill, J.; Branco, J., 2009b. Validations

of Vertebral Metrics: a mechanical instrument to

evaluate posture osf the spinal column.. O. Dössel and

W.C. Schlegel (Eds.): WC IFMBE Proceedings 25/VII,

711–713

Quaresma C, Forjaz Secca M, Goyri O’Neill J, Branco J.

Vertebral metrics: Application of a Mechanical

Instrument to Evaluate the Spinal Column in Pregnant

Women. Proc. Internacional Conference Biodevice

2010a; 143 – 146.

Quaresma C, João F, Fonseca M, Forjaz Secca M, Veloso

A, Goyri O’Neill J, Branco J. Comparative evaluation

of the tridimensional spine position measured with a

new instrument (Vertebral Metrics) and an

Optoelectronic System of Stereophotogrammetry.

Medical, Biological Engineering and Computing

2010b; 48(11): 1161-1164.

Sulij E, Mayers D. An Introduction to Numerical

Analysis. Cambridge. 2003.

VERTEBRAL METRICS: APPLICATION OF A INSTRUMENT TO EVALUATE THE SPINAL COLUMN IN

PREGNANT WOMEN

379