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 Table of Contents  
Year : 2022  |  Volume : 11  |  Issue : 1  |  Page : 23-29

Assessment of gestational age by new-born joint angles

1 Department of Pediatrics, NB Medical College, Siliguri, West Bengal, India
2 Department of Community Medicine, Medical College, Kolkata, West Bengal, India
3 Department of Biotechnology, Delhi Technological University, Delhi, India
4 Department of Microbiology, WBSU, Barasat, West Bengal, India
5 Department of Pediatrics, Medical College, Kolkata, West Bengal, India
6 Ex-Expert Experimental Mechanics, Delhi Technological University Delhi, New Delhi, India
7 Department of Pharmacology, IPGMER and SSKM Hospital, Kolkata, West Bengal, India
8 Department of Pediatric Medicine, Medical College, Kolkata, West Bengal, India

Date of Submission20-Sep-2021
Date of Acceptance19-Nov-2021
Date of Web Publication03-Jan-2022

Correspondence Address:
Rakesh Mondal
Department of Pediatrics, Medical College, Kolkata, West Bengal
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcn.jcn_116_21

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Objective: We aimed to measure the joint angles of major joints in newborn babies to explore their association with gestational age (GA). Materials and Methods: This observational study was conducted to evaluate joint angles in healthy newborn infants, born between 28 and 41 completed weeks of gestation. Healthy and hemodynamically stable babies were selected by purposive sampling up to the 2nd day of life. Six major joints of upper and lower limbs (shoulder, elbow, wrist, hip, knee, and ankle) were assessed on either side. The joint angles and range of motion (ROM) achieved through predefined passive movements were measured by a single observer using a manual acrylic goniometer. The positioning of the joints during measurement was standardized. Results: A total of 433 newborn babies, belonging to different GA, were evaluated. The joint angles and ROM did not show any significant differences between right and left sides and between male and female babies. The ROM of flexion-extension and adduction-abduction movement at shoulder, angle of palmer-flexion at wrist, and angle of dorsiflexion at ankle, were observed to correlate strongly with GA (correlation coefficient r of –0.75, –0.74, –0.73, and –0.73, respectively). The relationships were inverse. A mathematical model based upon multiple regression analysis is proposed to predict GA from these four measurements. Conclusions: Structured clinical assessment of major joint angles in newborn babies has the potential to provide relatively precise estimation of GA, which may be used to add accuracy to modified New Ballard Score.

Keywords: Articular goniometry, gestational age, joint angles, prediction model

How to cite this article:
Nandy A, Mondal T, Ivan DM, Sengupta T, Das SK, Goldar D, Hazra A, Mondal R. Assessment of gestational age by new-born joint angles. J Clin Neonatol 2022;11:23-9

How to cite this URL:
Nandy A, Mondal T, Ivan DM, Sengupta T, Das SK, Goldar D, Hazra A, Mondal R. Assessment of gestational age by new-born joint angles. J Clin Neonatol [serial online] 2022 [cited 2022 Dec 4];11:23-9. Available from: https://www.jcnonweb.com/text.asp?2022/11/1/23/334731

  Introduction Top

Clinical assessment of different major joints angle in newborn babies has been conventionally utilized in the verification of gestational age (GA). Accordingly, several maneuvers and signs are mentioned in the literature which have laid down the foundation of the scheme of GA evaluation.[1],[2] These describe passive movements involving the major joints in the newborn. The joint angles which are formed by various passive movements can be greatly influenced by the gradual development of muscle tone. This is the physiologic basis for the corroboration of joint angles with newborn maturity which is reflected in the GA at birth. However, in this context, a lacuna can be noticed about the nonavailability of precise quantification of joint angles in Indian newborns as per GA in completed weeks.[3] We sought to address the lacuna by generating corresponding data and exploring the potential association between newborn joint angles and their GA.

  Materials and Methods Top

Ours was an institution-based single center analytical observational study conducted with healthy and hemodynamically stable newborn infants aged up to 2 days of life. The participants were stratified according to their period of gestation in completed weeks, ranging between 28 and 41 weeks. Consecutive subjects who were delivered at our center or attended the outpatient clinic and met the inclusion and exclusion criteria were included if parental written informed consent was available. Sick newborns and babies with obvious congenital anomaly were not included. Furthermore, small for GA and large for GA newborn infants were screened with the help of Fenton's preterm growth chart and excluded from the study. Due approval from the Institutional Ethics Committee was taken beforehand.

GA of the participants was recorded from the antenatal ultrasound reports. It was compared with the GA documented from the last menstrual period of mother. In instances, where the two did not corroborate, New-Ballard Score (NBS) recorded for the participants was taken into consideration to obviate the risk of classification bias.

An 8-inch 360° plastic manual International Standards of Measurement goniometer (Baseline Evaluation Instruments, Model No. 12–100) made up of transparent acrylic material was used in the study to measure different joint angles. Minimum interval of recording for this instrument was 1°. All readings were taken by a single observer with the assistance of nursing staff. Standard aseptic precautions were followed in handling the babies.

Six major joints of upper and lower limbs (shoulder, elbow, wrist, hip, knee, and ankle) were evaluated on each side. The joint angles achieved through specific passive movements at the respective joints were measured. Shoulder and hip joint were evaluated for both flexion-extension and adduction-abduction movements, elbow and knee joint for flexion-extension movement, wrist joint for palmer flexion-dorsiflexion movement, and ankle joint for plantarflexion-dorsiflexion movement. Gentle pressure in contrast to the normal handling of newborn babies was applied while performing the predefined passive and rolling movements. For recording the joint angle, two lever arms of the joint served as the reference lines of the two limbs of the goniometer, whereas the joint itself acted as fulcrum. The meeting point of the lateral or anterior bisecting lines of the lever arms was taken as the reference point to measure different joint angles as applicable to the study procedure. The visual goniometric assessments of joint angles were expressed in degrees. Assessments of all the joint angles were done in lateral posture except the passive adduction-abduction movement of hip joint which was performed in the supine position.

The flexion-extension range of motion (ROM) at the shoulder joint was recorded with goniometer at the height of complete passive flexion and extension movement in a vertical plane which was placed at 30° internally rotated from the sagittal plane. ROM of adduction-abduction movement was recorded as complete passive adduction and abduction movement in a vertical plane which was placed at 30° internally rotated from the frontal plane, around the longitudinal axis of the articular interface. Owing to the natural angle of torsion of humeral upper end and scapular anteversion, the antero-posterior axis in the transverse plane of the articular interface of the shoulder joint was placed in such a manner which was approximately rotated 30° internally from the sagittal plane.[4],[5]

In the hip joint, the ranges of motion were recorded at the height of complete passive flexion and extension movement in the sagittal plane, and full adduction and abduction passive movement in the frontal plane, respectively, around the medio-lateral and antero-posterior axis of the articular interface. It is noteworthy that normal acetabular anteversion and angular torsion of femoral neck in the transverse plane had apparently nullified each other to place the antero-posterior axis of the articular interface of hip joint in the sagittal plane.[6],[7]

The joint angles formed in the sagittal plane at the elbow and knee joints were recorded after exercising complete passive flexion and extension movement. Similarly, the joint angles formed by complete passive palmer flexion and dorsiflexion movements at the wrist, and complete passive plantarflexion and dorsiflexion movements ankle joint were recorded successively in the sagittal plane. On certain instances where complete passive movement could not be performed, the angle of limitation for the movement was documented.

Statistical considerations

We did not go in for a formal sample size calculation for this descriptive study. Instead, based upon case load and logistical considerations, we aimed to recruit at least 30 participants for each completed week of gestation between 28 and 41 weeks or 420 subjects overall, irrespective of gender, through purposive sampling. Joint angle data were found to be normally distributed by Kolmogorov − Smirnov goodness-of-fit test. Descriptive statistics have been generated as mean and standard deviation and 95% confidence interval ranges, stratified by GA in completed weeks. Subgroup comparisons (left versus right; male versus female) were done by Student's paired samples or independent samples t-test, as appropriate, with cutoff for statistical significance at P < 0.05. Strength of association between angle or ROM of specific passive movements for individual joints (in degrees) and GA (in weeks) was quantified by calculating Pearson's product moment correlation coefficient (r), after verifying the linearity assumption through scatterplots. Statistica version 6 (Tulsa, Oklahoma: StatSoft Inc.; 2001) and MedCalc version 11.6 (Mariakerke, Belgium: MedCalc Software bvba; 2011) software were used for the statistical analysis.

  Results Top

Overall, 487 newborn babies were screened as probable participants of the study. For some (n = 16) parents did not give consent for study. On occasions (n = 35) all the predefined joint angles could not be assessed, whereas for few subjects (n = 3), inadmissible fallacy were noticed at the time of documenting the GA. Thus, data of 433 newborns were analyzed, which included 205 male (47.3%) and 228 female (52.7%) babies. Participants were stratified according to GA in completed weeks.

[Table 1] summarizes all the joint angles assessed in the 433 newborns with comparison between left and right sides. This summary is presented without stratification. Left-right comparisons by Student's paired samples t-test did not indicate any statistically significant differences. The comparisons between male and female babies (data not shown) by independent samples t-test also did not reveal any significant differences. This table also presents the strength of association between angles or ranges of individual movements (in degrees) and GA (in completed weeks) as Pearson's correlation coefficient (r) values. Evidently, strong inverse correlations (r > 0.65) are observed for all movements at shoulder joint, flexion at elbow, palmar flexion at wrist, palmar flexion-dorsiflexion at wrist, and plantar flexion and dorsiflexion at ankle. Most movements at hip and knee show good but not strong correlation (0.5 < r < 0.65).
Table 1: Goniometric joint angle measurements at 6 major synovial joints in newborn babies studied

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[Table 2] presents the joint angle measurements stratified by GA for the four movements that show the strongest correlations, namely passive flexion-extension ROM (r = –0.75) and passive adduction-abduction ROM (r = –0.74) at shoulder, passive palmer-flexion at wrist (r = –0.73), and passive dorsiflexion (r = –0.73) at ankle. [Figure 1], [Figure 2], [Figure 3], [Figure 4] present the scatter plots corresponding to these associations. Notably, all these associations are linear but inverse indicating the decline of joint flexibility with increasing GA.
Table 2: Selected goniometric joint angle measurements in newborns stratified by gestational age

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Figure 1: Scatter diagram showing the linear relationship of angle of passive flexion-extension range of motion at shoulder joint with newborn gestational age in completed weeks

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Figure 2: Scatter diagram showing the linear relationship of angle of passive adduction-abduction range of motion at shoulder joint with newborn gestational age in completed weeks

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Figure 3: Scatter diagram showing the linear relationship between angle of passive palmer-flexion at wrist and newborn gestational age in completed weeks

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Figure 4: Scatter diagram showing the linear relationship between angle of passive dorsiflexion at ankle and newborn gestational age in completed weeks

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Multiple linear regression analysis was performed to explore whether any consistent mathematical relationship can be deduced between these four strongly correlated joint angles and GA in completed weeks. The resultant regression equation was: GA (in completed weeks)= 51.054 – (0.033*A) – (0.035*B) – (0.031*C) – (0.037*D), where A represents angle of passive flexion-extension ROM at shoulder; B passiveadduction-abduction ROM at shoulder, C angle of passive palmer-flexion at wrist, and D angle of passive dorsiflexion at ankle, with all four variables being significant predictors. The overall model quality was very good with coefficient of determination R2 = 0.946, indicating that most of the variability in the outcome (GA) can be explained by the four predictors in the model.

  Discussion Top

Assessment of GA is a salient feature of clinical evaluation of newborn babies. The modified NBS helps considerably in this purpose. The method makes use of a composite scoring system to estimate newborn GA in a wide range of completed weeks. For neuromuscular maturity assessment, it has described approximate estimation of different joints angle in broad range of degrees with certain interval under the bare eye examination.[8] However, joint angle being a quantitative parameter, it is possible to get more precise value of the measurement. Evidently, these measurements in numbers have the potential to indicate newborn GA not only in completed weeks but possibly also in days if we are able to measure accurately and follow the principles of mathematics.

Different clinical methods have been postulated and assessed over the time to determine newborn infant maturity accurately.[9] The proposals from Amiel-Tison, Dubowitz et al., and Ballard et al. have left their trail on the subsequent works that are conducted in this field.[2],[10],[11] It was Claudine Amiel-Tison who first described from her observations on developmental physiology that muscle tone could have a direct association with the range of movements performed at the different joints in newborn infants.[2] The acquisition of muscle tone and motor functions is documented to follow caudo-cephalic pattern of progression during the 28–40 weeks of gestation where the development of flexor tone usually precedes extensor tone.[12],[13] Thus, measurements of the joints angle being achieved by passive movements can be used for evaluation of newborn maturity. However, the conundrum persists regarding estimation of the joints angle which are graded by scores to provide an impression on the status of newborn maturity. Instead, if the joint angles are measured precisely and comprehensively in newborns, the definite values of these measurements can reciprocate into explicit determination of the GA.

In our study, predefined passive movements at the major joints were evaluated in newborn babies of different GA using goniometric assessments in a standardized manner for the various joints. This has yielded precise data. Single observer assessment reduced the possibility of interobserver bias. As expected, laterality or gender did not introduce and differences. Correlation analysis indicated that passive flexion-extension ROM and passive adduction-abduction ROM at shoulder, angle of passive palmer flexion at wrist and angle of passive dorsiflexion at ankle had the strongest associations with newborn GA. The regression model obtained from the study indicates that goniometric assessment of joint angles could be utilized as a clinical tool to find GA of the newborn babies conforming to completed weeks.

Reference data of different newborn joint angles according to the completed weeks of newborn GA are scarce in the literature.[14],[15],[16] Some of the studies are conducted with similar objectives but their results cannot be compared as the subjects are recruited in cluster of weeks instead of specific groups of GA in completed weeks.[17],[18],[19],[20]

The primary limitation of this study is the fact that newborn babies lack bony landmarks which poses considerable difficulty in joint angle measurements. Although the possibility of interobserver bias was reduced in this by a single observer conducting the measurements, in actual clinical practice this difficulty can introduce subjective variability in measurements. Influence of other factors which can possibly affect the measurement of joints angle like volume of soft tissues and maternal antenatal medications have not been taken into the consideration.

  Conclusion Top

Despite these limitations, it is reasonable to conclude that standardized manual goniometric measurement of just four joint angles can help in precise estimation of newborn GA in completed weeks, which even may be used to add accuracy to modified NBS.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Usher R, McLean F, Scott KE. Judgment of fetal age. II. Clinical significance of gestational age and an objective method for its assessment. Pediatr Clin North Am 1966;13:835-62 contd.  Back to cited text no. 1
Amiel-Tison C. Neurological evaluation of the maturity of newborn infants. Arch Dis Child 1968;43:89-93.  Back to cited text no. 2
Nandy A, Guha A, Datta D, Mondal R. Evolution of clinical method for new-born infant maturity assessment. J Matern Fetal Neonatal Med 2020;33:2852-9.  Back to cited text no. 3
Norkin CC, White DJ. Measurement of Joint Motion: A Guide to Goniometry. 3rd ed. New Delhi: Jaypee Brothers Medical Publishers Private Limited; 2004. p. 3-12.  Back to cited text no. 4
Ludewig PM, Borstad JD. The shoulder complex. In: Levangie PK, Norkia CC, editors. Joint Structure and Function: A Comprehensive Analysis. 5th ed. New Delhi: Jaypee Brothers Medical Publishers Private Limited; 2012. p. 244-8.  Back to cited text no. 5
Wientroub S, Tardiman R, Green I, Salama R, Weissman SL. The development of the normal infantile hip as expressed by radiological measurements. Int Orthop 1981;4:239-41.  Back to cited text no. 6
McKibbin B. Anatomical factors in the stability of the hip joint in the newborn. J Bone Joint Surg Br 1970;52:148-59.  Back to cited text no. 7
Ballard JL, Khoury JC, Wedig K, Wang L, Eilers-Walsman BL, Lipp R. New Ballard score, expanded to include extremely premature infants. J Pediatr 1991;119:417-23.  Back to cited text no. 8
Wariyar U, Tin W, Hey E. Gestational assessment assessed. Arch Dis Child Fetal Neonatal Ed 1997;77:F216-20.  Back to cited text no. 9
Dubowitz LM, Dubowitz V, Goldberg C. Clinical assessment of gestational age in the newborn infant. J Pediatr 1970;77:1-10.  Back to cited text no. 10
Ballard JL, Novak KK, Driver M. A simplified score for assessment of fetal maturation of newly born infants. J Pediatr 1979;95:769-74.  Back to cited text no. 11
Illingworth RS. Normal Development. In: Nair MK, Russell PS, editors. Illingworth's The Development of the Infant and Young Child: Normal and Abnormal. 10th ed. New Delhi: Reed Elsevier India Private Limited; 2012. p. 92-3.  Back to cited text no. 12
Robinson RJ. Assessment of gestational age by neurological examination. Arch Dis Child 1966;41:437-47.  Back to cited text no. 13
Jayakrishnan TT, Sharma S, Gulati S, Pandey RM, Wadhwa S, Paul VK. Agreement between visual and goniometric assessments of adductor and popliteal angles in infants. J Pediatr Neurosci 2013;8:93-6.  Back to cited text no. 14
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Waugh KG, Minkel JL, Parker R, Coon VA. Measurement of selected hip, knee, and ankle joint motions in newborns. Phys Ther 1983;63:1616-21.  Back to cited text no. 16
Forero N, Okamura LA, Larson MA. Normal ranges of hip motion in neonates. J Pediatr Orthop 1989;9:391-5.  Back to cited text no. 17
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  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

  [Table 1], [Table 2]


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