|Year : 2016 | Volume
| Issue : 1 | Page : 17-20
Femoral neck shaft angles: A radiological anthropometry study
Thomas Oduntan Adekoya-Cole1, Olasode Israel Akinmokun2, Kofoworola O Soyebi3, Omachoko Emmanuel Oguche4
1 Department of Surgery, College of Medicine, University of Lagos; Department of Surgery, Lagos University Teaching Hospital, Idi-Araba, Lagos, Nigeria
2 Department of Accident and Emergency, Lagos University Teaching Hospital, Idi-Araba, Lagos, Nigeria
3 Department of Surgery, Lagos University Teaching Hospital, Idi-Araba; Department of Radiology, College of Medicine, University of Lagos, Lagos, Nigeria
4 Department of Surgery, Lagos University Teaching Hospital, Idi-Araba, Lagos, Nigeria
|Date of Web Publication||13-Apr-2016|
Thomas Oduntan Adekoya-Cole
Department of Surgery, College of Medicine, University of Lagos; Department of Surgery, Lagos University Teaching Hospital, Idi-Araba, Lagos
Source of Support: None, Conflict of Interest: None
Background: Most of the available orthopaedic implants were designed and manufactured based on data from Western population whose skeletal dimensions are different from those of Africans.
Objectives: This study was conducted to determine the value of the neck-shaft angle (NSA) of Nigerians living in Lagos for the purpose of adequate planning, preparation, and pre-operative selection of orthopaedic implants for surgeries involving the femoral neck and stocking of orthopaedic implants in hospitals located in resource poor countries like Nigeria.
Materials and Methods: This was a retrospective study which involved measuring the NSAs of anterior-posterior views of pelvic radiographs of adult patients reported "normal study" by the radiologist.
Results: A total of 264 femoral necks were analysed from 132 patients' radiographs comprising of 68 males and 64 females. The average NSA for an adult Nigerian living in Lagos is 130.77° ± 6.03° with mean NSA value of 131.28° ± 6.56° for the right and 130.22° ± 5.18° for the left. The mean value of NSA for an adult male is 131.57° ± 5.66° whereas the mean value for an adult female is 129.97° ± 6.33°.
Conclusion: The value of NSA obtained from this study should be considered during the surgical fixation of the neck of femur fractures or osteotomies around the neck of the femur of adult Nigerians. It should also be noted during designing and bioengineering construction of orthopaedic implants and hip prosthesis for Nigerians.
Keywords: Africans, collodiaphyseal angle, femoral neck, Lagos, neck shaft angle, Nigerians
|How to cite this article:|
Adekoya-Cole TO, Akinmokun OI, Soyebi KO, Oguche OE. Femoral neck shaft angles: A radiological anthropometry study. Niger Postgrad Med J 2016;23:17-20
|How to cite this URL:|
Adekoya-Cole TO, Akinmokun OI, Soyebi KO, Oguche OE. Femoral neck shaft angles: A radiological anthropometry study. Niger Postgrad Med J [serial online] 2016 [cited 2019 Aug 23];23:17-20. Available from: http://www.npmj.org/text.asp?2016/23/1/17/180130
| Introduction|| |
The femur, the longest and strongest bone in the human body, is made of various parts which include the femoral head which articulates with the acetabulum and the neck which joins the head with the long axis of the femoral shaft at an angle. This angle is known by many names, including neck-shaft angle (NSA), collodiaphyseal angle (CDA), diaphysio-femoral neck angle, angle of the neck of femur, angle of inclination, cervicodiaphyseal angle and collum diaphyseal angle.  This angle is necessary to enable the femoral shaft to swing clear of the pelvis during mobility.  The slope of the femoral neck is in line with the forward and upward propulsive thrust of normal progression.  The NSA is important in the control of lateral balance during mobility.  The angle of the NSA varies and it is noticed to be smaller in female.  (due to wider pelvis leading to greater inclination of the femoral shaft on the neck). The femoral NSA is generally set at 125°, but it can vary from 120° in females to 140° in males. ,,
This study was conducted to determine the value of the NSA of Nigerians living in Lagos, the largest city in Nigeria, located in the South-Western region of the country. We believe this study will help in the pre-operative selection of orthopaedic implants for surgeries involving the femoral neck and stocking of orthopaedic implants in hospitals located in resource poor countries like Nigeria. Knowledge of NSA is valuable in orthopaedic procedures such as fixation of femoral neck fractures. It is also helpful in designing and bioengineering construction of orthopaedic implants and hip prosthesis. Most of the available orthopaedic implants were designed and manufactured based on data from Western population whose skeletal dimensions are different from those of Africans.
| Materials and Methods|| |
This was a retrospective study which involved measuring the NSAs from radiographs of adult patients who had presented to Lagos University Teaching Hospital (LUTH). The radiographs selected were the anterior-posterior (AP) view of the pelvis showing both hip joints and upper femora. The X-rays were taken using standard protocols for AP pelvic X-rays; 15-30° internal rotation of the hips in the supine position with a film-focus distance of 100 cm, with the beam centred on the symphysis pubis. The radiographs obtained were from archives of the Radiology Department of LUTH. The radiographs used were those whose studies were carried out between years 2009 and 2013. The radiographs selected were those with no visible pathology and were reported as normal by the radiologist. The radiologist was involved in the selection of the radiographs.
The measurements were done with the aid of viewing box and single handheld 360° goniometer. The measurements were done by two researchers at different times, blinded to each other's findings and the average value was recorded as the final value. Before the commencement of the measurement, the two researchers discussed and had ten pelvic radiographs to test run their measurements. The NSA measured is the angle made by the intersection of the longitudinal axis of the neck with that of the longitudinal axis of the femoral shaft. The longitudinal axis of the neck was obtained by joining two midpoints of the diameters of the neck and the head of the femur while the longitudinal axis of the shaft of the femur was drawn by joining the midpoints of two points on the proximal shaft of the femur below the lesser trochanter. The angle formed by the intersection of the two axes was read off as the femoral NSA with the handheld goniometer [Figure 1],[Figure 2] and [Figure 3]. The same goniometer was used for all the measurements. The mean value of the left and the right femoral NSAs were recorded.
|Figure 1: Measurement of the left femoral neck shaft angle in a female subject|
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|Figure 2: Measurement of the right femoral neck shaft angle in a male subject|
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|Figure 3: Measurement of the left femoral neck shaft angle in a male subject|
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Data were recorded and statistical analysis was performed with Statistical Package for Social Sciences (SPSS Inc., Chicago, Illinois, USA, version 15.0). Frequency distribution tables were generated. The mean, median, range, and standard deviation were calculated. All statistical tests were two-tailed carried out at 5% level of significance.
| Results|| |
A total of 264 femoral necks were analysed from 132 patients' radiographs comprising of 68 males and 64 females. The age range was from 22 to 67 years with the mean age of 37.9 ± 8.4 years. The NSA of males ranges from 116° to 145° with a mean of 131.57° ± 5.66°. On laterality, the mean values for the right and left sides (for male) were 131.91° ± 6.14° and 131.15° ± 5.07°, respectively [Table 1].
The values of NSA for females range from 120° to 148°. The mean value for female NSA was 129.97° ± 6.33°. The mean value on the right side was 130.66° ± 7.16° whereas the mean value on the left side was 129.40° ± 5.31° [Table 1].
Overall, the mean value for both sexes was 130.77° ± 6.03° from NSA values that ranged from 116° to 148° on the right side and 120-143° on the left side. The modal NSA value were 130° on the right side and 128° on the left side with mean NSA value of 131.28° ± 6.56° for the right and 130.22° ± 5.18° for the left (P = 0.0001) [Table 2].
The values of the NSA in males were higher than the female values bilaterally [Table 3].
|Table 3: The statistical analysis of the values of neck shaft angles of both males and females|
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There are no correlations between sex and NSA bilaterally (P > 0.05) whereas right and left NSA were strongly correlated (P = 0.0001).
| Discussion|| |
A total of 264 femoral NSAs of 132 people's radiographs were used in this study. The number of radiographs used in this study was small. The small sample size was due the fact that there are other centres in Lagos that handle musculoskeletal conditions and careful selection of radiographs used for the study.
The mean NSA for adults living in Lagos, a city in South-Western Nigeria is 130.77° ± 6.03° with a mean value of 131.57° ± 5.66° for male and 129.97° ± 6.33° for female. The mean value obtained in this study is similar to the value documented by Gilligan et al.  in their study involving multiple areas in the world. Although the average value of NSA of modern human was given as 126.4° ± 5.57° in the study by Gilligan et al., the value documented for Nigeria was 129.5° (though only two dry bones were analysed in the study). Gilligan et al.  also documented NSA values for other tropical countries around Nigeria and these include NSA value of 132.3° for Chad, 130.8° for Mali, 132.5° for Senegal and 130.5° for Sudan. Gilligan et al.  further documented that most higher NSA were found in the tropics and warmer regions. Igbigbi,  in a study documented values of NSA as 133.3° ± 5.3° for males and 123.4° ± 5.8° for females in Uganda, whereas Otsianyi et al.  in a study of the Kenyan population, documented 128.21° ± 3.79° for males and 126.11° ± 3.22° for female. However, the values of 131.57° ± 5.66° for males obtained from this study is lower than the value documented by Tahir et al.  who studied NSA of Nigerians in the North-Eastern Nigeria. They documented values of 136.70° ± 3.905° and 126.65° ± 3.397° for males and females, respectively. Otsianyi et al.,  in their study among the Kenyans, also reported interethnic differences in the value of femoral CDA. They noticed that the nomadic and groups that usually walked long distances had values that are higher than the highland farmers. They proposed that the varying activities may be responsible for the variations. This may explain the differences in the values of NSA obtained from the study by Tahir et al. and our study. The Northerners are comprised different ethnic groups, of which some are nomads while the activities of the populace in Lagos are variable due to its cosmopolitan composition. However, a nationwide research to document the NSAs of all ethnic groups represented in Nigeria is recommended.
This study also revealed higher mean NSAs for males than for females, although statistically insignificant. This is as found by other workers. ,,, The smaller angles in women have been attributed to a number of reasons including the wider pelvis, greater bicondylar angle (obliquity of the shaft of the femur) and shorter femur.  Akbar and Kalimullah  in Pakistan, however, reported values of female NSA larger than that of the male, in both limbs. Radha et al.  also noted higher NSA in females than in males in Indian subjects. Of note is the fact that the highest value of NSA obtained in this study (148°) was from a radiograph of a female patient (as also seen in the study by Radha et al.  ) while the least value obtained (116°) was from the radiograph of a male patient!
The lateral difference was noted in this study. The mean NSA was statistically significantly higher on the right than the left. This was also reported by Nwoha  and Gilligan et al.  Gilligan et al.  postulated that the small lateral difference could be due to right leg dominance. Akbar and Kalimullah,  however, noted a larger left NSA in their study while other researchers , did not show neither gender variability nor lateral differences of statistical significance.
| Conclusion|| |
This study revealed that the NSA of an average adult in Lagos, Nigeria is 130.77° ± 6.03° with a mean value of 131.57° ± 5.66° for male and 129.97° ± 6.33° for female. The lateral difference was noted, with the value of the NSA higher on the right than the left. The value of NSA obtained from this study should be considered during the surgical fixation of the neck of femur fractures or osteotomies around the neck of the femur. It should also be noted during designing and bioengineering construction of orthopaedic implants and hip prosthesis for Nigerians.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]