Variations of the Anatomy and Bony Landmarks of Deep Circumflex Iliac Artery in a Select Kenyan Population

Abstract

Background: The deep circumflex iliac artery (DCIA) is a large caliber artery which branches laterally from the external iliac artery (EIA), directly opposite the origin of the inferior epigastric artery (IEA). Population variations have been reported in its origin, length, and branching patterns. These may alter its relationship to palpable surgical landmarks such as the anterior superior iliac spine (ASIS) and the pubic tubercle (PT) which are used to locate the artery preoperatively, thus predisposing it iatrogenic injury. Despite this, there is paucity of data from the Kenyan setting. Study Design: Cross-sectional study design. Objective: To determine the variations of the anatomy and bony landmarks of the Deep circumflex iliac artery in a select Kenyan population. Methods: A total of 104 DCIA from 52 formalin fixed adult cadavers were dissected to expose the DCIA, following which its vessel of origin and distance from the ASIS and PT, relation to the inguinal ligament (IL), length and branching patterns were noted. The average of the measurements were calculated. All data were collected and analyzed using Microsoft Excel 2007 (Microsoft Corporation, Redmond, WA). Representative photos of the vessel and its variations were taken. Results: The DCIA was found to be present and bilaterally symmetrical in all cadavers. In all cases observed, it originated as a lateral branch from the EIA (100%), opposite the IEA and directly behind the IL in 98% of the cases. Its average distance from the ASIS along the IL was 7.28 + 0.99, while it was 5.91 + 1.03 from the pubic tubercle to its origin. Its length ranged from 3.7 cm to 9.5 cm, with an average length of 3.86 cm in the right limb and 3.67 cm in the left limb. As regards its branching patterns, in 78% of the cases, it bifurcated into the horizontal and ascending branches, in 6%, it trifurcated and in 4%, it divided into more than 3, exhibiting a fine tree-like branching (arborization). Conclusion: The DCIA in our setting exhibited variations from other settings and an increase in awareness of these variations will probably reduce future iatrogenic lesions of the DCIA and its major branches in Kenya.

Introduction

The deep circumflex iliac artery (DCIA) is a large caliber artery which branches laterally from the external iliac artery (EIA), directly opposite the origin of the inferior epigastric artery (IEA). It ascends obliquely and laterally toward the anterior superior iliac spine (ASIS) behind the inguinal ligament (IL).[1] In majority of instances, opposite the ASIS, it divides into an ascending and a horizontal branch. The ascending branch runs between the transversus abdominis and the internal oblique muscles, supplying them.[2] The horizontal branch runs along the iliacus muscle and is the main source of blood supply to the iliac crest bone. The DCIA can vary greatly in its branching patterns which may pose difficulty in identifying it during surgery, especially, if the variant anatomy is not understood well.

Population variations have been reported in 3 key parameters: Its origin (can be located superior, inferior, or posterior to the IL), length (5 cm and 12 cm), and, finally, the branching pattern of the vessel.[2,3,4,5,6] These alter its relationship to palpable surgical landmarks such as the ASIS and the pubic tubercle (PT) which are used to locate the position of the artery preoperatively, thus predisposing it iatrogenic injury. These variations may also influence the choice of flap during restoration in head and neck region[7,8,9] and may be essential to prevent unnecessary incisions, scarring in the donor site and further explorative maneuvers when trying to locate the artery. In our setting, the DCIA flap is highly used in head and neck reconstructions. Despite this, there is a dearth of local data on the anatomy and bony landmarks of the DCIA in a Kenyan population. This study hence aims to determine the same.

Materials and Methods

A total of 104 DCIA from 52 formalin fixed adult cadavers were dissected at the Department of Human Anatomy, University of Nairobi. Ethical approval was sought and provided by the Department of Human Anatomy, University of Nairobi as per the Kenyan constitution. All specimen with femoral catheters or other medical issues disturbing the groin region were excluded.

The ASIS, PT, and IL were identified by palpation after which 3 incision lines were drawn (Figure 1). The first incision extended from the ASIS to the PT along the IL, the second, from the midpoint of the first incision line coursing in a vertical plane upwards for 5 cm, and the third from the line extended from the same midpoint 10 cm vertically downwards (Figure 1). The DCIA was then fully exposed following carefully reflection of fascia until the EIA and the DCIA were exposed (Figure 2).

All observations and measurements were done bilaterally. The point of origin of the DCIA was noted in relation to the inguinal ligament. Its length was measured from its origin to its point of bifurcation. Measurements from the origin to the ASIS, PT and to the point of termination of the artery were measured using digital Vernier calipers (Mitutoyo 500-196-30). The branching pattern was divided into 3 categories: bifurcation, trifurcation, and cases with more than 3 terminal branches: arborization, following reflection of the skin flaps. The average of the measurements were calculated. All data were collected and analyzed using Microsoft Excel 2007 (Microsoft Corporation, Redmond, WA). Representative photos of the vessel and its variations were taken.

Results

Origin of DCIA and Its Surgical Landmarks

The DCIA was found to be present and bilaterally symmetrical in all cadavers. In all cases observed, it originated as a lateral branch from the EIA (100%), opposite the IEA and directly behind the IL in 98% of the cases (Figure 3), while in 1.9%, a duplicated DCIA with two origins (one above and one posterior to the IL) was found (Figure 4). There was no femoral origin of DCIA. The distance from its origin to the ASIS and PT has been summarized (

Table 1. Mean Values of the Distance of Point of Origin of DCIA from ASIS and PT.

Dimension (cm)	Right limb	Left limb	Combined
ASIS to origin	7.27 + 1.01	7.29 + 0.97	7.28 + 0.99
PT to origin	5.98 + 0.99	5.83 + 1.06	5.91 + 1.03

ASIS, anterior superior iliac spine; PT, pubic tubercle.

).

Length of DCIA

The length of the DCIA ranged from 3.7 cm to 9.5 cm, with an average length of 3.86 cm + 1.80 cm in the right limb and 3.67 cm + 1.72 cm in the left limb. There was no statistically significant difference in the lengths of the DCIA between the two limbs (P ¼ .61).

Branching Pattern and Related Surface Landmarks

In 98% of cadavers dissected, the branching pattern of the DCIA was symmetrical bilaterally, whereas in 1 case, the left DCIA trifurcated while the right bifurcated. In 78% of the cases, it bifurcated into the horizontal and ascending branches (Figure 5), in 6%, it trifurcated and in 4% (Figure 6), it divided into more than 3, exhibiting a fine tree-like branching (arborization) (Figure 7). In the remaining 12% of the cases, the DCIA originated as 2 branches (the horizontal and ascending branches). The point of branching of the DCIA, from the ASIS was found to be 4.4 cm + 1.07 on the right side and 4.6 cm + 1.18 on the left side of the body. From the PT, the point of branching had a mean value of 8.2 cm bilaterally (+1.30 cm, 1.50 cm on the right and left sides, respectively). The distance of the horizontal branch of the DCIA from the ASIS along an ASIS to ASIS plane was measured and found to be at a distance of 2.77 + 0.58 cm and 3.22 + 1.53 cm on the right side of males and females, respectively. On the left side, in males and females, it lay at a distance of 2.80 + 0.53 and 2.83+ 0.54 cm, respectively.

Discussion

The DCIA has exhibited population variations on its origin, length, and branching pattern. The DCIA was present bilaterally in all cadavers dissected.

Origin and Surface Landmarks

Our findings showed that in all the cases observed, the DCIA originated from the EIA directly behind the IL. This is consistent with the findings of Vasanthkumar et al[5] and Kim et al.[2] Being found consistently behind the IL, the DCIA is predisposed to iatrogenic injury especially during incisions of the IL and as such care should be taken.

From our findings, the DCIA mostly originated from the EIA. This differed from studies by Vasanthkumar et al[5] and Kim et al[2] who showed that in 5%-36% of the cases, the DCIA can take origin from the femoral artery which was not the case in the current study. Duplication of DCIA found in this study is in keeping with previous observations, although the proportion is much higher in other populations.

The point of origin of the DCIA from the EIA was 6.0 cm on the right and 5.8 cm on the left from the PT. It was also noted that the DCIA was at an average of 7.28 cm from the ASIS along the inguinal ligament bilaterally. This distance was found to be greater than that found in German[3] and Korean[2] populations and as such care should be taken during its harvesting.

Ghassemi et al[3] and Adachi[10] reported instances where the DCIA originated from the IEA above the inguinal ligament. No such variants were encountered in this study. The variations noted in origin observed could possibly be related to racial differences observed among populations and they may influence the type of approach used in harvesting the artery and minimizing explorative procedures that may cause injury to structures in the pelvis. The IEA can also be used as a suitable landmark for the DCIA since it appears to have a consistent relationship with the origin of the DCIA.

Length

The DCIA had an average length of 3.77 cm. In comparison to the German,[3] Korean,[2] and Iranian[4] populations, the DCIA in the current population exhibited the longest length. Being longer, the DCIA may be more calibrous in our setting and this may allow the surgeon to repair defects that are relatively larger. A shorter DCIA will tend to cause stretch on the artery and therefore make the micro-anastomosis with the recipient vessel difficult which may lead to failure.[11] It is recommended that during the planning of facial reconstructive surgery, knowledge of the average DCIA pedicle length be utilized in selection of flaps to be used in repair of defects.[7]

As pertains the symmetry of the length of the vessels bilaterally, this was found in 95% of the samples we had, which was different from the findings by Penteado,[6] who found 66% symmetry.

Branching

The point of branching of the DCIA was noted to lie at an average of 4.50 cm from the ASIS and 8.26 cm from the PT bilaterally.

On the pattern of branching, the findings of a study done by Kim et al[2] on the Korean population on the patterns of branching in comparison to the current study have been summarized. In cases where the DCIA has no trunk, the terminal branches that originate directly from the EIA may not be calibrous enough for a successful anastomosis between it and the vessel at the recipient site. Knowledge about the trifurcation or aborization pattern of branching is important since it gives the surgeon leeway to harvest alternative branches if the horizontal and ascending branches are damaged or are absent in any case. However, the additional branches may result in unnecessary bleeding if cut which may also compromise the survival of the flap due to the reduced blood supply. The reason for the more diverse pattern of branching can be attributed to genetic differences in the populations.

Conclusion

The origin of the DCIA showed that it arose as a lateralward branch from the EIA, opposite and slightly inferior to the IEA. It did not have a common origin with the IEA in any of the cases. The origin was consistently found behind the IL in the Kenyan population at a distance of 7.3 cm bilaterally from the ASIS. Therefore, this can be used as a landmark to locate the DCIA origin. The findings of the length of the DCIA trunk revealed that it had a mean length of 3.77 cm before it divided into its terminal branches, and that this was longer than that found in other populations. It was also found that the branching pattern of the DCIA had variants such as trifurcations and an arborization pattern which are all of clinical importance. Increase in awareness of these variations will probably reduce future iatrogenic lesions of the DCIA and its major branches in Kenya.

Limitations

We could not get information on the cadavers’ exact age as well as BMI since the cadavers had been volunteered.