



ORIGINAL ARTICLE 

Year : 2018  Volume
: 17
 Issue : 2  Page : 6471 

Morphometric analysis of calcaneal angles in Igbos of south east of Nigeria and its clinical implication: A plain xray study
Amechi Uchenna Katchy^{1}, Ngozi Rosemary Njeze^{2}, David Okoroafor^{3}
^{1} Department of Accident and Emergency, University of Nigeria Teaching Hospital Enugu, Enugu, Nigeria ^{2} Department of Radiation Medicine, University of Nigeria Teaching Hospital Enugu, Enugu, Nigeria ^{3} Department of Radiology, Federal Teaching Hospital Abakiliki, Abakaliki, Nigeria
Date of Web Publication  24Jan2019 
Correspondence Address: Dr. Ngozi Rosemary Njeze Department of Radiation Medicine, University of Nigeria, Nsukka Nigeria
Source of Support: None, Conflict of Interest: None
DOI: 10.4103/njot.njot_15_18
Introduction: The calcaneum is repeatedly subjected to static and dynamic stresses especially in the weightbearing positions during walking, working or running and this is reflected in the trabecular pattern within the calcaneus. There are six radiological angles associated with this bone notably the Böhler (tuber joint) angle (BA) and Gissane's angle (GA), and they vary in different ethnic population. Aim: This is to determine the calcaneal angles among the ethnic Igbos of South Eastern Nigeria, determine the relationships between these angles, determine any correlation with gender and age, compare the values of the BA and GA to that of other populations and discuss the clinical implications of the determined values. Methodology: A 5year review of all lateral views of Xrays of the foot and ankle done at Federal Teaching Hospitals, Abakaliki, Nigeria, from 1^{st} January 2012 to 31^{st} December 2016, was done. Drawing and mathematical sets were used to measure the six radiological angles on the lateral views of plain Xray films of the ankle and subjected them to descriptive and inferential statistics. Results: There were 120 patients, 65 males and 55 females. The calcaneal angles among the ethnic Igbos of South Eastern Nigeria showed the following: BA: 32.58 ± 4.98, GA: 121.22 ± 6.11, calcaneal compression angle: 30.00 ± 3.01, talocalcaneal angle (TCA): 22.58 ± 5.28, calcaneal pitch angle: 17.35 ± 3.79 and apical angle (AA): 67.24 ± 7.27. There was no relationship between these angles. The TCA and AA showed a correlation with gender and age and other angles did not. There was a statistically significant difference between BA values in this study and that of Ugandan and American populations (P < 0.05). There was a statistically significant difference between the GA values in this study and that of Turkish, New Zealand and Indian populations. Conclusion: These determined values would be a useful tool in the management of patients of Igbo extraction with of the foot pathology.
Keywords: Calcaneal angles, clinical implications, Igbos
How to cite this article: Katchy AU, Njeze NR, Okoroafor D. Morphometric analysis of calcaneal angles in Igbos of south east of Nigeria and its clinical implication: A plain xray study. Niger J Orthop Trauma 2018;17:6471 
How to cite this URL: Katchy AU, Njeze NR, Okoroafor D. Morphometric analysis of calcaneal angles in Igbos of south east of Nigeria and its clinical implication: A plain xray study. Niger J Orthop Trauma [serial online] 2018 [cited 2019 Jun 15];17:6471. Available from: http://www.njotonline.org/text.asp?2018/17/2/64/250735 
Introduction   
The calcaneum is the largest of all the tarsal bones and a major bone in the hind foot. It articulates with the talus proximally and the cuboid anteriorly and shares a joint space with the talonavicular joint, known as the talocalcaneonavicular joint. The calcaneum transfers most of the body weight from the lower limb to the ground.
The calcaneum is repeatedly subjected to static and dynamic stresses, and this is reflected in the trabecular pattern within the calcaneus.^{[1]} There are six radiological angles associated with this bone, namely, Böhler (tuber joint) angle (BA/TJA), Gissane's angle (GA), calcaneal compression angle (CCA), talocalcaneal angle (TCA), calcaneal pitch angle (CPA) and apical angle (AA) of pseudocyst triangle.
These parameters are important in management of fractures of the calcaneum,^{[2],[3],[4]} and other hind foot disorders^{[5]} and they vary in different ethnic population.^{[6],[7],[8],[9],[10]} The Igbos are the largest ethnic group in Africa,^{[11],[12]} and the indigenous homeland of the Igbo people is the Southeastern part of Nigeria.^{[13],[14]} There is no published literature of these parameters of the Igbo ethnic group. Therefore, the aim of this study is to determine these calcaneal angles among the ethnic Igbos of the Southeastern Nigeria, to determine the relationships between these angles, to determine any correlation with gender and age, compare the values of the BA and GA to that of other populations and to discuss the clinical implications of the determined values.
Methodology   
A 5year review of all lateral views of Xrays of the ankle done at Federal University Teaching Hospital, Abakiliki Nigeria, from 1^{st} January 2012 to 31^{st} December 2016 was done. Xrays of adult patients, aged 18–64 years belonging to the Igbo ethnic group were included in the study. All patients with radiological proven calcaneal pathology (e.g. tumours, oldhealed or unhealed fractures, infections and osteoarthritis), patients whose epiphysis were still open, patients who had bone surgery on calcaneum and patients of nonIgbo origin as documented in the patient's profile were all excluded from the study.
Materials and Methods   
Drawing and mathematical sets were used to carry out the following measurements on standard lateral views of plain Xray films of the ankle/foot.
Angle measurements protocol
 BA/TJA [Figure 1]: A line was drawn from the highest point of the anterior process to the highest point of the posterior facet. A second line was drawn to run tangential to the superior edge of the tuberosity. The angle between the two lines was measured
 GA [Figure 2]:A line was drawn along the downward slope of the calcaneal superior surface. A second line was drawn along the upward slope of the calcaneal superior surface. The angle between these two lines was then measured
 CCA [Figure 3]: A line was drawn in the plane of the inferior surface of the calcaneus. A second line (identical to the first line of the BA) was drawn from the highest point of the anterior process to the highest point of the posterior facet. The angle between the two was then measured
 TCA [Figure 4]: A line was drawn along the long axis of the talus. A second line was drawn along that of the oscalcis. The angle between these two lines was then measured
 CPA [Figure 5]: A line originating at the lowest point on the calcaneum and joining the head of 5^{th} metatarsal bone was drawn. A second line originating from the same point to the lowest point of the calcaneocuboid joint was drawn. The angle in between these two lines was measured
 AA of pseudocyst triangle: The anterior and posterior compression trabeculae groups were identified [Figure 6]. The angle between them was measured.
Interobserver error
To reduce this, all measurements were taken twice by the same person measuring and using the same technique and equipment and the means recorded.
Statistical analysis
We used the statistical package Google sheets to analyse the data.
Descriptive statistics were calculated for all variables of interest. Continuous measures were summarised as means, standard deviations and medians. The P values for comparing means of continuous variables were determined after selecting a level of significance 0.05. We used a onesample ttest to compare the means of our values of BA and GA with that of some other published population. Pearson correlation was used to determine the relationship of the angles with one another. A 2way ANOVA was used to test the level of statistical significance of each angle with age group and sex.
Results   
[Table 1]a, [Table 1]b, [Table 1]c shows the descriptive statistics showing the value of the angles for male, female and both gender: there were 120 patients 65 (54.17%) males and 55 (45.83%) females. The mean for the calcaneal angles was as follows: BA: 32.58 ± 4.98, GA: 121.22 ± 6.11, CCA: 30.00 ± 3.01, TCA: 22.58 ± 5.28, CP: 17.35 ± 3.79, AA: 67.24 ± 7.27.  Table 1a: Descriptive statistics showing the calcaneal angles in males Table 1b: Descriptive statistics showing the calcaneal angles in females Table 1c: Descriptive statistics showing the calcaneal angles in both gender
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[Table 2]a shows the relationship between the BA and other angles: There was a negative correlation between the BA and GA.  Table 2a: Relationships between the angles Table 2b: Result of one sample test comparing our mean Bohler's angle with that of other populations Table 2c: Result of one sample test comparing our mean Gissane angle with that of other populations
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[Table 2]b shows the result of one sample test comparing mean BA with that of other populations: The P values for the compared populations means are as follows: American = 0.013, Nigerian = 0.889, Ugandan = 0.023, Sudi = 0.153, Turkish = 0.928.
[Table 2]c shows the result of one sample test comparing our mean GA with that of other populations: The P values for other compared population are as follows: Saudi = 0.067, Turkish = 0.001, New Zealander = 0.001, Egyptian = 0.269, Indian = 0.000.
[Table 3]a shows the comparison of BA in gender and age: The regression analysis had a value of 0.20286337. The different age groups and/or sex do not have equal means.  Table 3a: Comparison of Bohler angles in gender and age Table 3b: Comparison of gissane angles in gender and age Table 3c: Comparison of calcaneal compression angles in gender and age Table 3d: Comparison of talocalcaneal angles in gender and age Table 3e: Comparison of calcaneal pitch angles in gender and age Table 3f: Comparison of apical angle of pseudocyst triangle in gender and age
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[Table 3]b shows the comparison of GA in gender and age: The regression analysis showed a value of 0. 094391235.
[Table 3]c shows a comparison of calcaneal compression angles in gender and age: The regression analysis showed a value of 0.016746357.
[Table 3]d shows the comparison of TCA angles in gender and age: The regression analysis showed a value of 0.0159.
[Table 3]e shows the comparison of CPA in gender and age: The regression analysis showed a value of 0.7906.
[Table 3]f shows the comparison of AA in gender and age: The regression analysis showed a value of 0.000647.
Discussion   
Calcaneal angles are important in determining the effective reduction in calcaneal fractures as well assessment of deformities. The measured these angles in the plain Xray films of the Igbo subjects. The BA was introduced in 1931 by Dr. Lorenz Bohler,^{[6]} who gave a range of 30°–35° in his article. The study found a value of 32.58 ± 4.98 with a wider range of 21–42 compared with that of other populations there was a statistical significant difference between our values and that of Ugandan^{[8]} and American^{[9]} populations (P < 0.05). There was no statistical significant difference between our values and that of Saudi^{[16]} and Turkish^{[17]} populations (P > 0.05). Didia and Dimkpa^{[7]} had carried out a study of the value on the mixed Nigerian population, and our study did not show any statistical significant difference between the mixed population and that of the Igbo ethnic group. This is at variance with the findings of Didia and Dimkpa^{[7]} and Igbigbi and Mutesasira,^{[8]} who in their black Africans studies showed an ethnic and geographic variation for the angles. Our values for the BA did not show any gender difference (P > 0.05). This is at variance with the findings of Igbigbi and Mutesasira^{[8]} whose study showed a higher mean BA for women. Similarly, there was no age difference in mean BA values hence we rejected the null hypothesis (P > 0.05). This is at variance with the findings of Shoukry et al.,^{[10]} who found a negative relation between age and BA in his study on Egyptian population.
The value for our GA was established to be 121.22° ± 6.11° with a range of 111°–134°. The comparison of our value with that of the other populations demonstrated a statistical significant difference between our values and that of Indian,^{[2]} Turkish^{[17]} and New Zealand^{[19]} populations while there was no statistical difference between this study and that of Saudi^{[10]} and Egyptian^{[16]} populations. A comparison of our GA values with gender and sex rejected the null hypothesis (P > 0.05) as the different age groups and/or sex did not have equal means. This is in consonance with findings of Shoukry et al.,^{[10]} whose crosssectional study enabled them to analyse between the different age groups, and they found no significant correlation between age and calcaneal angles except with BA. Our findings is at variance with the findings of Khoshhal et al.,^{[16]} whose study demonstrated that the age group of 21–30 years had the highest GA while the age group of 21–30 years had the highest GA, though they demonstrated no difference in gender which is in keeping with our findings. Rokaya et al.^{[18]} had demonstrated that there was no significant difference in GA for gender (P = 0.212) This is similar to our findings on gender relationship with GA (P = 0.297).
The value of CCA was determined to be 30° ± 3.01°. An analysis of the relationship of this value with gender and age showed a statistically significant difference for age groups (P < 0.05) but showed no statistically significant difference for gender (P > 0.05). This is at variance with findings of Shoukry et al.^{[10]} on the Egyptian population who demonstrated no relationship between the angle and age (P = 0.841) though they got a similar value of 30.67° ± 2.94°.
The value of TCA was determined to be 22.58° ± 5.28° with a range of 14°–38°. This is at variance with the previous work done by Dahiru et al.,^{[20]} who established a value of 38.85° with a range of 18°–56° for a mixed Nigerian population and a value of 41.81 ± 7.46 with a range of 18°–56° for a separate Igbo population living in the Northern part of Nigeria. The reason for this wide difference in variation may be attributed to environment as bone morphometry is affected by geographical habitat.^{[20]} There is a correlation between TCA and gender and age (P < 0.05). This is at variance with the findings of Dahiru et al.,^{[20]} who had no correlation with age and gender in their study (P = 0.06).
The determined value for the CPA is 22.58° ±5.28° with a range of 11°–26°. Dahiru et al.^{[20]} found a mean value of 15.08 ± 2.87 and a value of 15.83 ± 6.31 for the Igbos living in his catchment area. There was no correlation between the angle and gender and age (P > 0.05) in our study and this is at variance with their findings which showed that the CP shows a statistically significant decrease with increasing age. The study determined a value of 67.24 ± 7.27 for our AA with a range of 50–84. There was a correlation between this values and gender and age (P < 0.05).
Clinical implications of the determined angles
The clinical implications for these measured angles are as follows.
The Bohler's angle
On the dry bone, there are small anatomic variations of the three references which give definition of the BA. Consequently, for evolutive study of each patient, the angle is a good reference for ankle morphology.^{[21]} A reduction of up to 20° or 10°, total obliteration and negative angle may occur if there is an upward displacement of the tuberosity or downwards displacement of the articular surface. Therefore, a decrease in this angle is suggestive of collapse of the posterior facet which is the weightbearing surface of the Oscalcis. The weight of the body shifts anteriorly when this occurs. Bohler^{[15]} had proposed in 1931, that in posterior facet fractures of the calcaneus, measuring the radiological angle of the tuberosity could be useful for the assessment of initial damage as well as evaluation of the quality of reduction. This is at variance with the views of McLaughlin,^{[22]} who pointed out that the BA has no usefulness and therefore has no prognostic value as the reduction or reversal of this angle indicates only the degree of proximal displacement of the tuberosity.
The Gissane's angle
There is a relationship existing between the posterior, anterior and middle facets, and the GA gives useful information about this relationship. The GA will be distorted in any axial compression forces with the talus acting as a bursting wedge with disruption of the subtalar joint.
Calcaneal compression angle
The angle represents the height of the calcaneus. In collapse and comminution of the bone, the angle is reduced. When there is extensive depression and rotation of the superior aspect of the os calcis. It can be used for the assessment of intraarticular calcaneal fractures.
Talocalcaneal angle
The inclination of the talus over the os calcis is measured by this angle. It provides a useful tool for the measurement of the hindfoot alignment. The TCA is increased when there is valgus angulation of the hindfoot. In patients with talipes equinovarus, the angle diminishes, approaching parallelism. Flat foot, metatarsus varus causes an increase of TCA, and congenital vertical talus decreases it.
Calcaneal pitch angle
In orthopedics specialty, there is no consensus for the measurement of medial longitudinal arch MLA.^{[23]} Some authors^{[24] ,[25]} have several suggested techniques which included among other things anthropometric and radiologic measurements.
Therefore, this angle can be used in measuring the medial longitudinal arch and can be used effectively in diagnosis of pes planus.^{[26]}
Apical angle of pseudocyst triangle
In osteoporosis, the angle between anterior and posterior compression trabeculae groups increases and in comminuted fractures it is disrupted.
Conclusion   
The calcaneal angles among the ethnic Igbos of the South Eastern Nigeria showed the following values: 32.58 ± 4.98, 121.22 ± 6.11, 30 ± 3.01, 22.58 ± 5.28, 17.35 ± 3.79, 67.24 ± 7.22 for BA, GA, CCA, TCA, CPA and AA, respectively. There were no relationships between these angles. The TCA and AA showed a correlation with gender and age and other angles did not. There was a statistical significant difference between BA values and that of Ugandan^{[15]} and American^{[16]} populations (P < 0.05). GA values showed a statistical significant difference between values and that of Turkish,^{[19]} New Zealand^{[20]} and Indian^{[22]} populations. These determined values would be a useful tool in the management of patients with ankle pathology who are of Igbo extraction.
Acknowledgment
The authors also are grateful to Osahon Osabuohien of Schlumberger Nigeria for the statistical analysis. We are grateful to the Xray Departments of Federal Teaching Hospital Abakaliki, Ebonyi State, for providing us with materials for our study.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3]
