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Table of Contents   
ORIGINAL RESEARCH  
Year : 2013  |  Volume : 24  |  Issue : 5  |  Page : 562-566
Risk of musculoskeletal disorders in upper limbs in dental students: Concordance of different methods for estimation of body angle


Department of Social Dentistry, Araraquara School of Dentistry, UNESP, SP, Brazil

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Date of Submission11-Sep-2012
Date of Decision05-Mar-2013
Date of Acceptance28-Mar-2013
Date of Web Publication21-Dec-2013
 

   Abstract 

Aims: The purpose of this paper was to evaluate the agreement among different methods used to estimate angular deviation of the body to determine the risk for development of upper limb musculoskeletal disorders in dentistry undergraduates.
Materials and Methods: Students (n = 79) enrolled in the final year undergraduate course of the Araraquara School of Dentistry-Sγo Paulo State University-UNESP were evaluated. Photographs were taken of students performing clinical procedures. The work postures adopted by each student were evaluated by means of rapid upper limb assessment (RULA). The basis used to obtain the individual's final risk score is the measurement of the angular deviations in the neutral positions of the regions evaluated. Two methods were used to estimate the angular deviation of the body: Visual exam and Image Tool software. A RULA final risk score was attributed to each procedure the student performed (n = 333). Study of the agreement between the methods about risk of musculoskeletal disorders was conducted by means of Kappa (κ) statistics. The level of significance adopted was 5%.
Results: Fair agreement (κ = 0.32) between the evaluated methods was verified.
Conclusion: The risk for development of upper limb musculoskeletal disorders by dentistry undergraduates evaluated by using RULA was not in agreement with the results obtained by use of visual exam and Image Tool.

Keywords: Dentistry, musculoskeletal disorders, occupational health

How to cite this article:
Garcia PS, Campos JB. Risk of musculoskeletal disorders in upper limbs in dental students: Concordance of different methods for estimation of body angle. Indian J Dent Res 2013;24:562-6

How to cite this URL:
Garcia PS, Campos JB. Risk of musculoskeletal disorders in upper limbs in dental students: Concordance of different methods for estimation of body angle. Indian J Dent Res [serial online] 2013 [cited 2020 Feb 25];24:562-6. Available from: http://www.ijdr.in/text.asp?2013/24/5/562/123367
Considering that body posture is one of the main risk factors for musculoskeletal disorders in dentistry, dentists' working postures should be evaluated. [1],[2]

Observational methods are frequently used as they allow an understanding of the effects of body posture on the articulations of the musculoskeletal system. [1],[3],[4],[5] The literature cites [6] some observational methods for the evaluation of body posture during the work, such as Video Technique for Analyzing Postures and Movements-VIRA, Method for the Identification of Musculoskeletal Stress Factors, which may have injurious effects-PLIBEL, Portable ergonomic observation-PEO, Postural and Repetitive Risk-Factors Index-PRRI, Ovako Working Posture Analyzing System-OWAS, Rapid Upper Limb Assessment-RULA, and the Occupational Repetitive Action Index-OCRA the latter 3 are recommended by International Standard Organization-ISO 11228, third part.

Some observational methods evaluate the angular deviation from the neutral position of segments of the body by means of visual perception, in order to estimate the risk of developing musculoskeletal disorders. Among these methods, RULA, [7] offers rapid analysis of postures of the neck, trunk and upper limbs, together with muscular function and external load received by the body, without interfering in the individual's work process. [7],[8],[9] RULA was the method chosen because it allows rapid observation of the upper limbs for the identification of the risk of developing occupational diseases and muscular efforts associated with working posture. In dentistry, the professional's work is sedentary, and generally, the postures are static, with ample use of the upper limbs, which may result in overload. For evaluation of the risk of development of musculoskeletal disorders in these professionals, RULA may be a feasible alternative since it was elaborated for the evaluation of sedentary activities. [10]

However, for the risk estimate obtained to be reliable and valid, measurement of the angular deviation must be adequately performed and hence that the result obtained will not be a distortion of reality. [11] This estimate may be made visually or with the aid of software that take measurements of angular deviations of the analyzed segments of the body. [12]

As there is scarcity in the literature of studies that compare the reproducibility of different methods for the analysis of angular deviation, particularly in dentistry, studies that propose to do this are necessary and pertinent.

Therefore, this study was conducted with the aim of evaluating agreement on the estimate of risk for developing musculoskeletal disorder of the upper limbs, in dentistry undergraduates, by means of RULA using the different methods for estimating angular deviation of the body.


   Materials and Methods Top


Casuistic

This was an observational study and this study was approved by the Research Ethics Committee of the School of Dentistry of Araraquara, Sγo Paulo State University-UNESP (40/08). The sample was composed of students (n = 75) of both genders, enrolled in the final year undergraduate course of the Araraquara School of Dentistry-UNESP, who agreed to participate. The students were evaluated with regard to working postures adopted during the performance of various clinical procedures (n = 333).

Record of working postures

Photographs were taken of students although performing diverse clinical procedures, using a digital camera. The photographs were taken in three defined points in order to allow analysis of angular deviation of the forearm, arm, wrist, neck, trunk, and legs.

Posture evaluation method

The working postures adopted by each student although acting as "operator" were evaluated by means of the RULA. [7]

The RULA method analyzes only one side of the body at a time; that is to say, it issues a final risk score of only one side of the body, generally, the side most used by the individual. Six regions of the body are evaluated (arm, forearm, wrist, neck, trunk and legs) and a risk score is attributed to each of these regions. In order to issue these scores, the evaluator bases his/her analysis on the angular deviation from the neutral posture of the body regions evaluated and hence those that show a lower angular deviation will have the lowest scores, representing less risk.

After obtaining the scores related to the posture of each part of the body, the manner of using the muscle group being evaluated and load/force placed on the muscles are also evaluated. For these 2 factors, the scores with lower values also represent lower risk.

At the end of the entire evaluation process, final risk scores are obtained, which may be classified as low risk; that is to say fair (scores one and two), medium risk with the need for future investigations with posture changes in the long-term (scores three and four), high-risk with the need for rapid investigation for changes in the short term (scores five and six) and extremely high-risk, with urgent investigations and changes in these postures to reduce excessive load on the musculoskeletal system (score seven).

Evaluation of procedures performed

During analysis of the photographs 2 methods of analysis for estimating the angular deviation of body regions by RULA were used, Image Tool software, [13] in which measurements were made of the angles of the regions of interest, and visual exam, whereby the researcher visually estimated the measurements of the angles.

The photographs were evaluated by a duly calibrated researcher (Image Tool κ = 0.910; visual exam κ = 0.885).

Statistical analysis

Descriptive statistics were performed. To evaluate agreement on the final score of estimated risk for musculoskeletal disorders as well as the estimated risk scores for each segment of the body evaluated by means of visual exam and Image Tool software Kappa (κ) statistics were used. Inter-method agreement was classified according to the proposal of Landis and Koch. [14] The level of significance adopted was 5%.


   Results Top


The major part of the clinical procedures was carried out by four hands (68.2%). Emphasis is laid on rehabilitative treatments (59.2%) and those performed in the maxillary arch (57.3%).

The distribution of the clinical procedures performed, according to the risk for developing musculoskeletal disorders in the upper limbs, using two different methods for estimating angular deviation of the body (visual exam and Image Tool software) may be seen in [Table 1].
Table 1: Distribution of the clinical procedures performed according to the classification of risk of musculoskeletal disorders, using visual exam and Image Tool program to estimate angular deviation. Araraquara/SP-Brazil, 2010


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Fair agreement (κ = 0.32) between the evaluated methods was verified, and for the visual exam a larger number of individuals with a risk score classified as medium and high were observed when compared with Image Tool.

The distribution of scores attributed to the upper limb postures (arm, forearm and wrist) according to the different methods for estimating angular deviation of the body (visual exam and Image Tool program) may be seen in [Table 2].
Table 2: Distribution of scores attributed to postures of body segments (arm, forearm and wrist) according to two different forms of estimating angular deviation of the body (visual exam and Image Tool program). Araraquara/ SP-Brazil, 2010


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For the upper limbs, adequate agreement between the evaluation methods was observed only in the forearm evaluation.

The distribution of scores attributed to the postures of the neck, trunk, and legs evaluated according to the two different forms of estimating angular deviation of the body (visual exam and Image Tool program) may be seen in [Table 3].
Table 3: Distribution of scores attributed to postures of body segments (neck, trunk and legs) according to the two different forms of estimating angular deviation of the body (visual exam and Image Tool program). Araraquara/SP-Brazil, 2010


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For the above-mentioned parts of the body that were evaluated, adequate agreement between the methods was observed only for the legs.


   Discussion Top


Evaluation of the quality of measurements that assess workers' exposure risk factors for the development of musculoskeletal disorders is extremely important in order to conduct studies with reliable results [12] because any error in the evaluation will influence the worker's final risk analysis, with direct consequences for his/her health, in the short, medium and long term, particularly when "false negative" results are obtained.

In view of this, proposal in this study was to verify the agreement on the risk of developing musculoskeletal disorders of the upper limbs of undergraduate dentistry students, using the visual exam and Image Tool program as methods for estimating the angular deviation, considering that there is scarcity of studies of this nature, particularly in dentistry.

Fair agreement (κ = 0.32) was observed [Table 1] between the methods evaluated. Comparison between the results of this study and those of others in the literature is limited as the aims and methodologies used are not similar. Nevertheless, it would be interesting to emphasize some of the findings. Genaidy et al. [1] found that the 20 engineering students who had analysis of the angular deviation of predefined postural angles of the shoulder performed by means of visual exam, presented errors of estimation in these analyses. Baluyut et al. [15] noted that the individuals who participated in the process of visual estimation of static non neutral postures of various regions of the body found greater difficulty in evaluating the upper limbs, particularly the elbow and wrist. Morrison et al. [16] also found low agreement in the estimation of angular measurements when the visual exam was used.

The limitation in agreement between the estimation methods tested may perhaps be explained because, when using Image Tool program, the evaluator selects the points he/she wishes to measure makes the exact measurement of the selected angles, whereas in the visual exam, by means of his/her visual perception, the evaluator makes an estimate of the angle formed.

In the present study, it was also possible to observe a larger number of individuals with a risk score classified as medium and high in the visual exam, and a larger number classified as extremely high in Image Tool [Table 1]. These results suggest that in the visual exam, there was a tendency for the researcher to underestimate the angular deviations of the body regions evaluated as was also observed by Genaidy et al. [1],[3]

In an attempt to observe in which analyzed region of the body the disagreements occurred a study was conducted for each segment of the body separately. It was verified that in the segment composed of the arm, forearm and wrist, there was adequate agreement between the methods of evaluation for the forearm only [Table 2]. A possible explanation for this result may be related to the criterion for issues forearm scores: Score one is attributed when the forearm flexion is from 60° to 100°; Score two when there is flexion of 100° or more; and if the forearm crosses the individual's midline, or if it is laterally outside of 45°, one more point must be added to the score. [7] In dentistry, as a result of the dental chair thickness and observation of the distance of 30-40 cm from the patient's mouth to the operator's eyes, [17] the operative field ends up being well above elbow level, which obliges the individual to perform great forearm flexion to reach it, being greater than 100°. Another aspect to point out is that when students sitting in the 9 and 11 o'clock positions, [18] they invariable end up crossing their midline and in this case, RULA asks for another point to be added to the forearm score. Even when adopting the position of 7 o'clock, [18] if the operator's forearm is situated laterally, another point is also added to his/her score. Therefore, this situation is easily observed visually as the angle formed by the forearm is very large, which makes it easy to estimate by visual exam, to the point of this analysis also corresponding to that performed by Image Tool. Genaidy et al. [1] and Morrison et al. [16] also verified that the larger angles are easier to examine adequately by visual exam.

When observing agreement on the arm and wrist, it was verified that it was acceptable for the arm and weak for the wrist, with a larger number of procedures with lower scores for the visual exam, confirming the supposition that the smaller angles had been underestimated.

For the segment composed of the neck, trunk, and legs [Table 3], it was verified that only the legs presented adequate agreement between the methods. In RULA, the score for the legs is the easiest to evaluate because there are only two scores, and there is a great distinction between them: Score one is attributed when the individual is seated, with legs and feet well supported, with body weight equally distributed; and score two, when there is no adequate support of the legs and feet, or the body weight is badly distributed. [7] Attributing these scores in the visual exam clearly leaves no doubts, and for Image Tool, in spite of measurement being made of the angle formed between the thigh and a leg to verify whether it is around 90°, judgment with the aid of visual exam is also necessary. Possibly this characteristic of attributing scores to legs has led to adequate agreement between the methods in this region of the body.

Whereas, it was found [Table 3] that both for the neck (κ = 0.33) and trunk (κ = 0.39) agreement between the methods was fair acceptable. For the neck, almost all the procedures (n = 332) were attributed high-risk scores in Image Tool. In the visual exam, in addition to this number being lower (n = 302), it was verified that some procedures were categorized in the lower risk scores; that is to say, one and two (n = 31). For the trunk, from the analysis by Image Tool it could be noted that scores two or three (n = 237) were attributed to the larger portion of procedures, whereas, in the visual exam the most frequently recorded scores were one and two (n = 243). These results confirm the trend toward minimizing risk scores by the visual exam.

Another interesting aspect to relate is that irrespective of the method used for estimating the angular deviation, it was verified that there was high-risk for the development of musculoskeletal disorders among dental students. In addition, it was noted that in spite of the visual exam being easier and simpler to perform, it appears to underestimate postures of risk, and therefore, further researches must be conducted with the purpose of drawing up strategies to make it feasible to use the visual exam in this type of population.

It was concluded that there was no agreement on the estimation of risk of developing musculoskeletal disorders of the upper limbs in dentistry undergraduates when the visual exam and Image Tool were used as methods for measuring the angular deviation of the body.

 
   References Top

1.Genaidy AM, Simmons RJ, Guo L, Hidalgo JA. Can visual perception be used to estimate body part angles? Ergonomics 1993;36:323-9.  Back to cited text no. 1
    
2.James CP, Harburn KL, Kramer JF. Cumulative trauma disorders in the upper extremities: Reliability of the postural and repetitive risk-factors index. Arch Phys Med Rehabil 1997;78:860-6.  Back to cited text no. 2
    
3.Genaidy AM, Al-Shedi AA, Karwowski W. Postural stress analysis in industry. Appl Ergon 1994;25:77-87.  Back to cited text no. 3
    
4.Juul-Kristensen B, Fallentin N, Ekdahl C. Criteria for classification of posture in repetitive work by observation methods: A review. Int J Ind Ergon 1997;19:397-411.  Back to cited text no. 4
    
5.Kjellberg K, Johnsson C, Proper K, Olsson E, Hagberg M. An observation instrument for assessment of work technique in patient transfer tasks. Appl Ergon 2000;31:139-50.  Back to cited text no. 5
    
6.Hayes M, Cockrell D, Smith DR. A systematic review of musculoskeletal disorders among dental professionals. Int J Dent Hyg 2009;7:159-65.  Back to cited text no. 6
    
7.McAtamney L, Corlett NE. RULA: A survey method for the investigation of work-related upper limb disorders. Appl Ergon 1993;24:91-9.  Back to cited text no. 7
    
8.Gandavadi A, Ramsay JR, Burke FJ. Assessment of dental student posture in two seating conditions using RULA methodology-a pilot study. Br Dent J 2007;203:601-5.  Back to cited text no. 8
    
9.Massaccesi M, Pagnotta A, Soccetti A, Masali M, Masiero C, Greco F. Investigation of work-related disorders in truck drivers using RULA method. Appl Ergon 2003;34:303-7.  Back to cited text no. 9
    
10.Garcia PP, Pinelli C, Derceli JR, Campos JA. Musculoskeletal disorders in upper limbs in dental students : e0 xposure level to risk factors. Braz J Oral Sci 2012;11:148-53.  Back to cited text no. 10
    
11.Fransson-Hall C, Gloria R, Kilbom A, Winkel J, Karlqvist L, Wiktorin C, et al. A portable ergonomic observation method (PEO) for computerized on-line recording of postures and manual handling. Appl Ergon 1995;26:93-100.  Back to cited text no. 11
    
12.David GC. Ergonomic methods for assessing exposure to risk factors for work-related musculoskeletal disorders. Occup Med (Lond) 2005;55:190-9.  Back to cited text no. 12
    
13.Wilcox DC, Dove SB, McDavid WD, Greer DB. UTHSCSA Image Tool-Version 3.0. 2008. Available from http://www.ddsdxuthscsaedu/dig/itdeschtml. [Last accessed on 2008 Oct 22].  Back to cited text no. 13
    
14.Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977;33:159-74.  Back to cited text no. 14
    
15.Baluyut R, Genaidy AM, Davis LS, Shell RL, Simmons RL. Use of visual perception in estimating static postural stresses: Magnitudes and sources of errors. Ergonomics 1995;38:1841-50.  Back to cited text no. 15
    
16.Morrison CS, Knudson D, Clayburn C, Haywood P. Accuracy of visual estimates of joint angle and angular velocity using criterion movements. Percept Mot Skills 2005;100:599-606.  Back to cited text no. 16
    
17.Valachi B, Valachi K. Preventing musculoskeletal disorders in clinical dentistry: Strategies to address the mechanisms leading to musculoskeletal disorders. J Am Dent Assoc 2003;134:1604-12.  Back to cited text no. 17
    
18.Valachi B. Ergonomic positioning: A few degrees add years to your career. Dent Today 2010;29:124-6.  Back to cited text no. 18
    

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Correspondence Address:
Patrícia Petromilli Nordi Sasso Garcia
Department of Social Dentistry, Araraquara School of Dentistry, UNESP, SP
Brazil
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Source of Support: The State of São Paulo Research Foundation–FAPESP (Research Aid Process number 2009/01896-2),, Conflict of Interest: None


DOI: 10.4103/0970-9290.123367

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    Tables

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