|Year : 2014 | Volume
| Issue : 2 | Page : 165-169
Anatomical study of diaphyseal nutrient foramina in human adult humerus
Vijayalakshmi S Bhojaraja1, Sneha Guruprasad Kalthur2, Antony S Dsouza2
1 Department of Anatomy, RAK College of Medical Science, RAK Medical and Health Science University, Ras Al Khaimah, United Arab Emirates
2 Department of Anatomy, Kasturba Medical College, Manipal University, Manipal, Karnataka, India
|Date of Web Publication||11-Nov-2014|
Sneha Guruprasad Kalthur
Department of Anatomy, Kasturba Medical College, Manipal University, Manipal, Karnataka
Source of Support: None, Conflict of Interest: None
Purpose: The objective of the following study is to determine the variation in diaphyseal nutrient foramen (NF) of humerus with respect to their number, location, direction and size. Materials and Methods: The present study was conducted on 100 humeri. The number and direction of diaphyseal NF were observed in all bones with the help of a hand lens. Position was described into horizontal and vertical zones; caliber was determined using hypodermic needles. Foraminal index was also calculated. Results: The mean length of humerus observed in the present study was 30.7 cm. The NF was situated at 17.8 cm from the proximal end, 12.4 cm from the distal end and ~2.9 cm below the mid length of humerus. The mean foramina index and circumference of NF was 57.7 and 6.2 cm respectively. Majority of the humeri (77%) had single NF while in 3% of humeri NF was absent. Middle one-third and on the antero-medial surface of the humerus was the most common location of the foramen. Majority of the dominant foramen was large in size and all were directing toward the distal end. Conclusion: The results of the present investigation indicate that there is variation in the number, location and size of NF in humeri among Indian population. An accurate knowledge of the location of the NF in long bones can be useful in certain surgical procedures such as bone grafting, microsurgical vascularized bone transplantation and in fractures.
Keywords: Diaphysis, humerus, nutrient artery, nutrient foramina
|How to cite this article:|
Bhojaraja VS, Kalthur SG, Dsouza AS. Anatomical study of diaphyseal nutrient foramina in human adult humerus
. Arch Med Health Sci 2014;2:165-9
| Introduction|| |
Bone is a highly vascular mineralized connective tissue which performs numerous vital functions in the human body. The blood supply to the bones varies according to the shape of the bone. In long bones, there are generally three sets of vessels: The diaphyseal, metaphyseal and epiphyseal arteries. The diaphyseal nutrient artery is the main source of blood to long bones, especially during its active growth period and the early stages of ossification. With their accompanying veins, these arteries usually penetrate the cortex obliquely through the nutrient foramen (NF) which leads into nutrient canals. 
Absence of NF and hence the nutrient artery can deplete the blood supply to the ossifying bones and can result in ischemia of metaphysic and growth plate. , Apart from this, injury to the nutrient artery at the time of fracture, or during subsequent manipulation and surgery may be a significant predisposing factor to faulty union of long bones.  Non-union of the humeral shaft remains a difficult clinical problem as the healing of fractures is dependent upon blood supply. ,
The number, position and direction of NF may vary. In the humerus, the NF is commonly present slightly below the midpoint of the antero-medial surface (AMS) close to the medial border (MB) and is directed downwards. ,
Knowledge of the location, number and direction of the NF in the humerus is not only important in understanding the physiology of development of bone but also are of significance in healing of fractured bones and orthopedic surgeries. Earlier studies have shown that the location and number of NF varies with geographic location. In the present investigation, we wanted to assess whether there is any variation among the Indian population with respect to the location, number and direction of the NF in humerus.
| Materials and Methods|| |
The study was conducted on 100 human humerus (49 right side, 51 left side) preserved in Department of Anatomy, Kasturba Medical College, Manipal, Manipal University. All the bones were from adults (>20 years) and were of unknown sex. Prior approval was obtained from the Institutional Ethics Committee to conduct the study.
- Number of NF: In bones having more than one foramen, the larger sized foramen was recorded as the dominant foramen and the other smaller as secondary foramen.
- Direction and obliquity was noted.
- Position of NF was described into horizontal and vertical zones. Horizontal zone was with respect to the surface and border. Any foramen lying within 1 mm from any border was taken to be lying on that border.  Vertical zone was with respect to length of the bone, which was divided into three zones that is upper one-third, middle one-third and lower one-third.
- Caliber: Three hypodermic needles with the caliber of 20G, 24G and 26G were used to determine the caliber of foramina. 
- Total length: The total length of the bone was measured using osteometric board.
- Foraminal index (FI): The FI was calculated by using the formula, FI = (DNF * TL)/100, where DNF is the distance from the proximal end of the bone to the NF and TL is the total bone length. 
- Circumference of the bone at the level of NF was noted with a help of a wire and measured using Vernier caliper.
Data was analyzed using SPSS software.
| Results|| |
The number of NF in humerus was recorded. The frequency of bone with single NF was highest (77%) while 18% of humeri had two NF. Only 2% of bones had four NF in them. NF was absent in 3% of humeri. When the right and left side humeri were analyzed separately, the frequency of variation in the number of NF was almost similar [Figure 1]. The directions of nutrient canal in humerus were directed toward the distal end. The location of NF was observed at different borders or surfaces of the humerus. In 49% of cases AMS had NF followed by MB, anterolateral surface (ALS) and posterior surface (PS). Only one bone had NF on the lateral border. In none of the humeri there was NF on the anterior border (AB). Bones which had more than 2 NF where classified as dominant having larger caliber and the other smaller as secondary. Out of total 122 NF 107 were dominant NF and 15 were secondary [Figure 2]. In vertical zone majority of NF were observed in middle 1/3 rd AMS. Very few diaphyseal NF were seen in lower 1/3 rd and none were present in upper 1/3 rd [Figure 3]. Different sizes of NF ranging from very small to very large were observed and only dominant foramina caliber was noted. Majority was of large caliber followed by a very small caliber and then medium caliber was very few in number [Figure 4]. Regarding metrical parameter the mean length of humerus observed in the present study was 30.7 cm. The NF was situated at 17.8 cm from the proximal end and 12.4 cm from the distal end. On an average ~2.9 cm below the mid length of humerus the NF were present. The mean FI and mean circumference of NF was 57.7 and 6.2 cm respectively [Table 1].
|Figure 1: Number of nutrient foramen in right and left humeri of adult South Indian population (n = 100). Statistical evaluation: aP < 0.0001 compared to humeri with 0, 2 and 3 foramen on right and left side, bP < 0.0001 compared with 0 and 3 foramen on right and left side|
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|Figure 2: Location of nutrient foramen on right and left humeri of adult South Indian population (n = 100) AB: Anterior border, MB: Medial border, LB: Lateral border, IB: Intermediate border, PB:|
Posterior border, AS: Anterior surface, AMS: Antero-medial surface, ALS: Anterolateral surface, LS: Lateral surface, MS: Medial surface, PS: Posterior surface. Statistical evaluation: aP < 0.001 compared to the number of bones in the rest of the locations, bP < 0.001 compared with no. of nutrient foramen in the rest of the locations
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|Figure 3: Schematic diagram showing location of nutrient foramen in humeri of adult human bones in vertical zone and horizontal zones|
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|Figure 4: Various sizes of nutrient foramina observed in humeri (right and left together) in South Indian population (n = 100). Statistical evaluation: aP < 0.001 compared with the rest of the size of nutrient foramen|
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| Discussion|| |
In our study, humeri with single NF were most common (77%) followed by two (18%) and three NF (2%) which is similar to earlier reports. , In contrast, a study by Mysorekar  reported only 50% of humeri with single foramen. None of the humeri in our study had more than three foramina [Table 2] while Mysorekar  and Kizilkanat et al.  have observed humeri with even up to 4 NF. In our study 3% of humeri did not have NF. Even though long bones are supplied by epiphyseal arteries apart from nutrient arteries, it is not clear whether the epiphyseal arteries can nourish them during growth. Or it may be possible that nutrient vessels have altered course in bones with absent NF.
|Table 2: Comparative analysis of number and size of nutrient foramen in humeri of adult human bones reported from the previous study with the present study|
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Comparative analysis of size of NF in humeri of adult human bones was done with the previous study [Table 2]. The size of the NF was noted using 20G, 24G and 26G hypodermic needle and classified as large, medium and small NF. In the present study about 85.2% of the NF was of large caliber which was not in agreement with earlier reports on Indian,  Turkish  and Spanish population.  In the present study, it was also observed about 1.6% of NF were of very small size caliber through which 26G hypodermic needle could not pass through which was not observed by previous authors. ,,,, The results clearly indicate that the size of the NF varies among Indian population and other population at different geographic location.
In the present study highest percentages of NF were located within the middle one-third of the bone followed by lower one-third which agrees with previous reports. ,, None of the humeri in the present study had NF in upper one-third of the bone unlike in earlier reports. ,, In addition, when the location of the NF on the horizontal zone was analyzed, the most common position was AMS which agrees with earlier reports ,,,, followed by the MB, ALS and PS. We did not observe any NF on the AB or on spiral groove as reported by earlier studies ,,,, [Table 3].
|Table 3: Comparative analysis of location of nutrient foramen in humeri of adult human bones reported from the previous study with the present study|
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The mean length of the humerus observed in the present study was 30.7 2.17 cm. This agrees with some of the earlier reports by Carroll  Kizilkanat et al.,  Nagel  and Gualdi and Galletti  Even though these studies are done on different population there was no significant difference in the mean length of humerus.
The FI of humerus in the present study which was similar to that of Spanish population.  On the contrary, Mysorekar  in his study have reported that FI ranges from as low as 26.51% to 74.46% respectively [Table 4]. The study subjects in this study were 180 which are almost 2 times higher than the sample size used in the present study which could explain the differences observed in these two studies. A recent study conducted by Kizilkanat et al.  on Turkish population indicated that FI of humerus can range from 15% to 69.4% in overall length of humerus. While study conducted by Pereira et al.  on Brazilian population it ranged from 32.1% to 68.8% respectively. In conclusion the foramina were located on the diaphysis 41.11-66.86% of the overall length of the humerus. Therefore, surgeons should take into consideration of this range of FI for some orthopedic applications such as total hip arthroplasty.
|Table 4: Comparative analysis of foraminal index and mean length of humeri of adult human bones reported from the previous study with the present study|
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Overall, the comparative analysis of the results of the present study with previous reports on Indian and other population clearly suggests that variation in NF with respect to their number; location, caliber etc. are common. Nagel  has described the risks for intra-operative injury to the nutrient artery during its exposure while placing internal fixation. This knowledge about these foramina is useful in the surgical procedures to preserve the circulation of the long bones. If surgeons could avoid a limited area of the cortex of humerus containing NF, particularly during open reduction, an improvement in management of non-union might be attained.
| Conclusion|| |
The NF with respect to the location in the humeri, majority were on the middle third AMS of the bone directing toward the distal end and of large size caliber. An accurate knowledge of the location of the NF in long bones can be useful in certain surgical procedures: In bone grafting, in microsurgical vascularized bone transplantation and in many fractures. It helps to prevent intra-operative injuries in orthopedic, as well as in plastic and reconstructive surgery. Delayed or non-union following trauma may be directly related to the absence of nutrient arteries entering the bones.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4]