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ORIGINAL ARTICLE
Year : 2020  |  Volume : 23  |  Issue : 1  |  Page : 7-11

Clinical measurement of angular profile of the knee and correlation with intermalleolar distance in children in Enugu metropolis


1 Department of Accident and Emergency/Surgery, Enugu State University of Science and Technology, Teaching Hospital Enugu, Enugu, Nigeria
2 Chief Consultant Orthopaedic Surgeon, City Specialist Hospital Enugu, Enugu, Nigeria
3 Chief Consultant Orthopaedic Surgeon, National Orthopaedic Hospital Enugu, Enugu, Nigeria
4 Chief Consultant Orthopaedic/Spine Surgeon, National Orthopaedic Hospital Enugu, Enugu, Nigeria
5 Consultant Orthopaedic Surgeon/Senior Lecturer, University of Nigeria Teaching Hospital Enugu, Enugu, Nigeria
6 Consultant Orthopaedic Surgeon, National Orthopaedic Hospital, Enugu, Nigeria

Date of Submission27-Mar-2019
Date of Acceptance04-Sep-2019
Date of Web Publication10-Jan-2020

Correspondence Address:
Dr. H C Ekwedigwe
Department of Accident and Emergency, Enugu State University of Science and Technology, Teaching Hospital Parklane, Enugu
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njcp.njcp_175_19

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   Abstract 


Background: Angular deformities of the lower limbs are commonly encountered deformities in pediatric orthopedic clinics. The values of the tibiofemoral angle undergoes changes as the child grows and these changes are self-limiting. The aim of the study is to establish the normal variation of knee angles of children between 2 and 12 years of age in Enugu metropolis and to establish any correlation between the knee angles and the intermalleolar distances (IMDs). Subjects and Methods: This study was done on 630 school children in Enugu metropolis between the age groups of 2 and 12 years. Multistage sampling was used in the study. The tibiofemoral angles and intermalleolar/intercondylar distances were measured. Results: The maximum tibiofemoral angle from this study was 7.6° ± 2.4° and the age corresponding to this value was 4 years. Only 23 subjects (3.5%) had varus knee angle. The values of the mean tibiofemoral angle and IMDs plateaued from 8 to 12 years. There was a significant positive correlation between average knee angle and IMD (r = 0.785, P < 0.001). Conclusion: The physiological changes in the knee angle (tibiofemoral) follow a similar pattern as established in the literature and there was positive correlation between IMD and the tibiofemoral angle.

Keywords: Genu varus, genu valgus, intermalleolar/intercondylar distance, tibiofemoral angle


How to cite this article:
Ekwedigwe H C, Enweani U N, Madu K A, Nwadinigwe C U, Okwesili I C, Ekwunife R T. Clinical measurement of angular profile of the knee and correlation with intermalleolar distance in children in Enugu metropolis. Niger J Clin Pract 2020;23:7-11

How to cite this URL:
Ekwedigwe H C, Enweani U N, Madu K A, Nwadinigwe C U, Okwesili I C, Ekwunife R T. Clinical measurement of angular profile of the knee and correlation with intermalleolar distance in children in Enugu metropolis. Niger J Clin Pract [serial online] 2020 [cited 2020 Jul 3];23:7-11. Available from: http://www.njcponline.com/text.asp?2020/23/1/7/275613




   Introduction Top


Angular deformities around the knee are one of the common cause of presentation at pediatric orthopedic clinic. Although these conditions are commonly benign and self-limiting, they often cause great concern to parents and relatives. The knee angle is defined by the mechanical axis of the femur intersecting the mechanical axis of the tibia. Lateral bending of the knee is known as genu varus and medial bending of the knee is known as genu valgus. The values for the genu varus and genu valgus becomes abnormal when they are greater than two standard deviations from the normal for that particular age group.[1] Development of the knee angle from varus alignment in the infant to valgus alignment in early childhood as part of normal physiological development is well documented.[2],[3] Such normal ranges have been reported in studies from various regions some of which suggest that there are regional variations.[4]

Salenius et al.[2] in their series on 1,279 Caucasian children between birth and 16 years of age found a mean varus alignment of 15° in newborns, this decreased to approximately 10° of varus alignment by 1 year of age, neutral alignment occurred between 18 and 20 months of age. The maximum valgus of approximately 12° was achieved by 3 to 4 years of age, the results were similar for boys and girls, and by the age of 7 years the children's valgus alignment had corrected to those of normal adults. Salenius et al.[2] and Sass et al.[1] in separate articles estimated that in approximately 95% of the children, physiologic genu varum or valgum alignments resolved spontaneously with growth. Cahuzac et al.[5] reported a similar pattern of variation of knee angle with growth as above, however they further demonstrated that boys tend to have decrease in valgus alignment towards skeletal maturity. Studies done in Chinese children revealed mean alignment of the knee at 2 years to be 5° valgus with intermalleolar distance (IMD) of 2.1 cm, these persist until 7 years of age.[4] Oginni et al.[6] in southwest Nigeria reported maximum uniform valgus of 7.1° ± 1.4° between 3 and 3.5 years, Odatuwa-Omagbemi[7] obtained maximum mean valgus tibiofemoral angle of 8.4° at 3 years, while Harcourt[8] documented maximum mean tibiofemoral angle of 7.58° in male and 7.04° in females at 4 years. The ages at peak valgus angulation reported by Oginni et al.,[6] Odatuwa-Omagbemi,[7] and Harcourt[8] all in Nigeria are similar to that reported by studies done abroad; viz Samia et al.[9] reported maximum valgus of 9.46° at 3–4 years in Saudi children, Salenius and Vankka[2] had their maximum peak valgus at 3–4 years in Caucasian children. However, Turkish, Saudi, and Caucasian children had higher peak valgus values of 9.6° to 9.8°, 9.46°, and 12°, respectively,[2],[9] These variations may be due to racial differences, techniques of measurement, and observer related factors.

Authors had suggested the use of intercondylar or IMDs only in the assessment of the progress of genu varus or valgus deformity.[4] This was supported by positive correlation between the knee angle and IMD which was reported by different authors.[4],[7],[8],[10]

The clinical method of assessing the knee angle is widely used as it is noninvasive, easy, reliable, and reproducible.[11] Another method that can be used to assess the tibiofemoral angle is the radiologic method, measurements are done on plane radiographs of the lower limbs.[2] It has disadvantage of exposure to irradiation. The photographic method has also been used by some authors.[3]

The available study in the south-east region of Nigeria on the tibiofemoral angle was done in children from 4 to 7 years, hence there is paucity of data for reference purposes in this region of the country. This present study was done in children aged 2 to 12 years.

The objectives of this study are to establish the normal variation of knee angles in children between 2 and 12 years in Enugu metropolis, to measure the intermalleolar/intercondylar distances, and to establish any correlation between the knee angles and the IMDs.


   Subjects and Methods Top


The study was done in three local government areas of Enugu metropolis of south-eastern Nigeria, viz: Enugu north, Enugu south and Enugu east. This was a cross-sectional descriptive study. The study population included children from 2 to 12 years of age. Ethical clearance was obtained from the Ethics Committee of National Orthopedic Hospital, Enugu. Approval for carrying out the study in each of the selected schools was obtained from Enugu state ministries of Education and Health. Written informed consent was also obtained from the Parent/Guardian of all the participants. Exclusion criteria were presence of overt musculoskeletal disorders affecting the lower limb such as Blount's disease, windswept deformities, unilateral genu varus or valgus deformity, and obvious deformities following fractures or malunion, children whose guardians decline and non-Nigerians. The sample size of 246 was calculated using the Cochrane formula,[12] n = Z2 pq/e2.

n = sample size.

Z = standard score. The level of confidence given (1.96 or 95%)

p = estimate of percent success; 0.8.

e = proportion of sample error = 0.05.

q = (1–P) = % failure, = 0.02

The sample size was increased to 630 to give greater precision to the study. A multistage sampling technique was used.[13] The list of all the government schools in all the three local government areas that comprise Enugu metropolis was obtained from Enugu state ministry of Education. A total of nine schools were selected for the study, a primary school, nursery school, and a community secondary school was selected from each of the three local government areas. The required number of subjects, 70 from each school was selected by systematic random sampling method. All the measurements were done by the researcher. Standard Goniometer was used to measure the tibiofemoral angles while nonstretchable measuring tape was used to measure the intermalleolar and intercondylar distances. Intraobserver variation was eliminated by measuring all the parameters three times in each child and taking the average. Subjects were required to undress, wearing only their pants. Screen was applied for privacy and a chaperone was around during the measurements especially for female subjects, a junior colleague helped to record the values.

Each child was positioned erect with the patellar pointing forward, the knees or ankles were positioned with the condyles or malleoli touching each other, this is shown in [Figure 1]. A standard goniometer was placed with its arms over the axes of the tibia and femur and its center on the center of the patella, the arms should be pointing to anterior superior iliac spine proximally and the second toe distally. The value of the tibiofemoral angle was then read off.[4],[11] The valgus angle was expressed as positive degrees and varus angle as negative degrees for ease of statistical analysis. These parameters were measured in both limbs. The intercondylar or IMDs were measured using a standard measuring tape. The horizontal distance between the medial malleoli was measured and recorded as IMD, where the IMD is zero the horizontal distance between the condyles of both femur was measured as the intercondylar distance. The values were recorded in cm.
Figure 1: The graph of knee angle against the age groups

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Data collated were analyzed using IBM SPSS-Statistics version 22. Means and standard deviations were obtained for continuous variables while categorical variables were summarized using frequency and percentages. Mean comparisons of continuous variables were done using one-way ANOVA and Duncan multiple comparison tests. Pearson's correlation was used to test relationship between continuous variables. P value less than 0.05 was regarded as significant. Results were presented in tables and charts.


   Results Top


The male to female ratio of subjects was 1:1. The number of subjects with valgus knee angle was 607, while only 23 subjects had a varus knee angle. None of the subjects had neutral knee angle. The maximum valgus orientation was obtained at 4 years of age with value of 7.6° ± 2.4°. There was significant difference in the average knee angles across the ages (F = 38.611, P < 0.001), however average knee angles obtained from 8 to 12 years were not significantly different from each other, this is shown in [Table 1]. The result also shows that the female subjects have significantly higher mean knee angles at ages 3, 4, 7, 8, 9, 10, and 12 years. [Figure 2] shows no remarkable difference between right and left knee angles. [Table 2] shows the distribution of IMD across the ages, the IMD has the highest value of 3.46±1.09 cm at 3 years, there was significant difference in the IMDs across the age ranges (F = 14.993). However the mean IMDs plateaued from 8 to 12 years of age. Around 23 subjects had varus knee angle and intercondylar distances greater than 0 cm, their average values were listed in [Table 3]. There is a significant positive correlation between average knee angle and IMD (r = 0.785, P < 0.001) as shown in [Table 4].
Table 1: Mean average knee angles (valgus, tibiofemoral) according to age

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Figure 2: The image shows the measurement of the knee angle

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Table 2: Mean Intermalleolar distances

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Table 3: Mean varus knee angles and their intercondylar distances

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Table 4: Correlation between average knee angle and intermalleolar distance

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   Discussion Top


The clinical method was used in this study because it is cost-effective, reliable, reproducible, and radiation-free, several authors had used the clinical method in their study on tibiofemoral angle.[4],[5],[10]

The tibiofemoral angle undergoes changes as the child grows from infant to early adolescent. These had been widely documented by researchers.[2],[4],[5],[7],[9],[10] The results obtained in this study shows that the subjects already had valgus orientation at 2 years of age, this is similar to findings documented by Salenius et al.[2] that neutral alignment occurred between 18 and 20 months of age and thereafter it changes to valgus alignment. Maximum valgus orientation was obtained at 4 years of age in this study, however, peak valgus at 3 years is not significantly different from the value obtained at 4 years. A similar age for peak valgus angle was reported in previous studies.[2],[6],[7],[8],[9] The value of maximum valgus angle obtained from this study is similar to what was obtained from previous studies done in the west African subregion, viz. the maximum knee angle obtained in a study done at southwest Nigeria was 8.4°,[11] Harcourt[8] in his work in south-east Nigeria had a maximum mean valgus angle of 7.58° ± 2.05° in males and 7.04° ± 1.86° in females, Oginni et al.[6] obtained maximum valgus of 7.1° ± 1.4° between 3 and 3.5 years, and Anirejuoritse et al.[12] obtained a maximum valgus of 7.87°. Physicians should be aware of this trend in the normal development of the knee angle to avoid making an unnecessary diagnosis of pathologic genu valgus deformity. Studies that were done on Turkish, Saudi, and Caucasian children showed they have higher peak valgus angles.[2],[9],[14] This might be due to racial differences and the use of different techniques to measure the knee angle could also be the reason for the variation.

Furthermore, this study shows that the tibiofemoral angle plateaued from 8 to 12 years, stabilized between 3.8° and 4.5° valgus. This is similar to what was reported by Oginni et al.[6]. Salenius et al.[2], and Yoo et al.[15] noted that the tibiofemoral angle plateaued after 8 years to adult value but at a higher value of 6° to 8°. Turkish children reached a final adult value of 6.6° and 7.5° in boys and girls, respectively. Moreover, it is important to note that the valgus angle continued to decrease after 8 years in Indian and Turkish children until skeletal maturity.[10],[14] The differences observed above might be due to racial differences.

Also results from this study show that there was no significant difference between the right and left knee angles. Similar studies did not report significant differences between the right and left knee angles.[10]

The mean peak valgus knee angle was significantly more in females when compared to that of males at 3, 4, 7, 8, 9, 10, and 12 years. Previous studies had varied results as regards any significant difference between the male and female knee angles. Salenius and Vankka,[2] Samia et al.,[9] Anirejuoritse,[12] and Harcourt[8] reported no significant difference between male and female knee angles in their respective studies. Yoo et al.,[15] and Matthew et al.[10] reported significantly higher female knee angles especially as the age increased. Even though there is a difference between male and female values, these appear insufficient for gender to be considered as a major factor in the evolution of the tibiofemoral angle.

The value and trend of the IMD obtained from this work are comparable with that reported from previous works. Omagbemi[7] reported mean peak valgus IMD of 2.5 cm at 3 years of age which decreased to 0.7 cm at 8 years of age. Matthew et al.[10] reported a maximum IMD of 3.3 cm. Cheng et al.[4] reported maximum IMD of 2.8 cm at 3 years which decreased to 0 ± 3 cm at 8 years of age.

This work shows that there is a significant positive correlation between average knee angle and IMD (r = 0.785, P < 0.001). Findings from other studies also showed this strong correlation. Omagbemi[7] in his work reported correlation coefficient of r = 0.765 between IMD and the tibiofemoral angle. Cheng et al.[4] reported correlation coefficient of r = 0.71 for boys and 0.74 for girls in Chinese children. Harcourt[8] reported a correlation coefficient of r = 0.77. Matthew et al.[10] obtained a correlation coefficient of r = 0.7147 in both boys and girls. A lower degree of correlation was recorded by Arazi et al.[14] in Turkish children (r = 0.40 for boys and r = 0.43 for girls). Authors had suggested the use of intermalleolar/intercondylar distances only in the assessment of progress of genu varum/valgum deformity.[4] However, some other authors feel tibiofemoral angle is a more reliable measurement tool.[5],[10],[14] Generally, it is believed that using the tibiofemoral angle is more reliable and affords better accuracy.

In conclusion, the physiological changes in the knee angle (tibiofemoral) as a child grows follows similar pattern as established in the literature except for some variations observed in Saudi, Turkish, and Caucasian children. Also there is a positive correlation between IMD and the tibiofemoral angle, it is recommended that IMD may be used as a screening tool in large populations like schools to estimate presence or absence of pathologic genu varus or valgus deformity.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Sass P, Hassan G. Lower extremity abnormalities in Children. Am Fam Physician 2003;68:461-8.  Back to cited text no. 1
    
2.
Salenius P, Vankka E. The development of the Tibio-femoral angle in children. J. Bone and Joint Surgery Am 1975;57:259-61.  Back to cited text no. 2
    
3.
Heath CH, Staheli LT. Normal limits of knee angle in white children – Genu varum and valgum. J Paediatr Orthop 1993;13:259-62.  Back to cited text no. 3
    
4.
Cheng JCY, Chan PS, Chiang SC, Hui PW. Angular and rotational profile of the lower limb in 2630 Chinese children. J Paediatr Orthop 1991;11:154-61.  Back to cited text no. 4
    
5.
Cahuzac JPH, Vardon D, De Gauzy JS. Developement of clinical tibiofemoral angle in normal adolescents. J Bone Joint Surg 1995;77-B: 729-32.  Back to cited text no. 5
    
6.
Oginni LM, Badru OS, Sharp CA, Davie MW, Worsfold M. Knee angles and Rickets in Nigerian children. J Pediatr Orthop 2004;24:403-7.  Back to cited text no. 6
    
7.
Odatuwa-Omagbemi DO. Clinical Assessment of Angular and Rotational Profile of the Lower limbs of Nigerian Children in Lagos: Part II Dissertation (FMCOrth) to the National Post-graduate Medical College of Nigeria. May 2009. p. 1-27. Available from: https://www.dissertation.npmcn.edu.ng/index.php/FMCS/article/download/1394/88. [Last cited on 2019 Mar 20].  Back to cited text no. 7
    
8.
dsHarcourt SL. Clinical Assessment of Tibiofemoral Angle in Children 4 – 7 years of age in Enugu. Part II Dissertation (FMCOrth) to the National Post-graduate Medical College of Nigeria. 2004. p. 1-46. Available from: https://www.dissertation.npmcn.edu.ng. [Last cited on 2019 Mar 20].  Back to cited text no. 8
    
9.
Samia A, Rahman SA, Wafa A, Badahdah WA. Normal development of Tibiofemoral angle in Saudi children from 2–12 years of age. World Appl Sci J 2011;12:1353-61.  Back to cited text no. 9
    
10.
Mathew SE, Madhuri V. Clinical Tibiofemoral angle in South Indian children. Bone Joint Res 2013;2:155-61.  Back to cited text no. 10
    
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Parrot A, Tousignant M, St-Cyr Y. normative Reference Values for Musculoskeletal Conditions and Functional Motor Abilities in the Paediatric Population. 2010. p. 228-65. Available from: https://www.irdpq.qc.ca.communication/publications/documents_disponibles.html. [Last cited on 2019 Mar 20].  Back to cited text no. 11
    
12.
Anirejuoritse B, Omota B, Ogbemudia A. Correlation between clinical tibiofemoral angle and body mass index in normal Nigerian children. Int Orthop 2012;36:1247-53.  Back to cited text no. 12
    
13.
Araoye MO. Research Methodology with Statistics for Health and Social Sciences. 1st ed. Ilorin, Nigeria: Nathadex Publishers; 2004. p. 123-6.  Back to cited text no. 13
    
14.
Arazi M, Ogun TC, Memik R. Normal developement of the tibiofemoral angle in Children: A clinical study of 590 normal subjects from 3 to 17 years of age. J Pediatr Orthop 2001;21:264-7.  Back to cited text no. 14
    
15.
Yoo JH, Choi IH, Choi TJ, Yoo WJ. Developement of tibiofemoral angle in Korean children. J Korean Med Sci 2008;23:714-7.  Back to cited text no. 15
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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