The inferior gluteal artery anatomy: a detailed analysis with implications for plastic and reconstructive surgery

Abstract

Background: The inferior gluteal artery (IGA) is a large terminal branch of the anterior division of the internal iliac artery (ADIIA). There is a significant lack of data regarding the variable anatomy of the IGA.

Materials and methods: A retrospective study was conducted to establish anatomical variations, their prevalence and morphometrical data on IGA and its branches. The results of 75 consecutive patients who underwent pelvic computed
tomography angiography were analysed.

Results: The origin variation of each IGA was deeply analysed. Four origin variations have been observed. The most common type O1 occurred in 86 of the studied cases (62.3%). The median IGA length was set to be 68.50 mm (lower quartile [LQ]: 54.29; higher quartile [HQ]: 86.06). The median distance from the origin of the ADIIA to the origin of the IGA was set to be 38.22 mm (LQ: 20.22; HQ: 55.97). The median origin diameter of the IGA was established at 4.69 mm
(LQ: 4.13; HQ: 5.45).

Conclusions: The present study thoroughly analysed the complete anatomy of the IGA and the branches of the ADIIA. A novel classification system for the origin of the IGA was created, where the most prevalent origin was from the ADIIA (type 1; 62.3%). Furthermore, the morphometric properties (such as the diameter and length) of the branches of the ADIIA were analysed. This data may be incredibly useful for physicians performing operations in the pelvis, such as interventional intraarterial procedures or various gynaecological surgeries.

INTRODUCTION

The inferior gluteal artery (IGA) (Fig. 1) is a large terminal branch of the anterior division of the internal iliac artery (ADIIA). It courses posteriorly between the sacral nerves (typically S2 and S3) and exits the pelvis through the inferior section of the greater sciatic foramen, below the piriformis muscle. The IGA supplies the skin and muscles of the buttocks (through muscular branches to the piriformis, obturator internus, and gluteus maximus muscles), as well as the posterior surface of the thigh. Furthermore, it gives off a companion branch to the sciatic nerve, as well as contributing branches to the trochanteric and cruciate anastomoses [15].

Figure 1. Inferior gluteal artery and its close anatomical area; 1 — inferior gluteal artery; 2 — inferior gluteal vein; 3 — inferior gluteal nerve; 4 — superior gluteal artery; 5 — sacrotuberous ligament; 6 — ischial tuberosity; 7 — gluteus maximus muscle; 8 — piriformis muscle; 9 — gluteus medius muscle.

There is a significant lack of data regarding the variable anatomy of the IGA. The arterial anatomy of the pelvis is known for being highly variable, making it a difficult area to operate in [12, 16, 26, 27]. The origin of the IGA has not been sufficiently studied in the past, even though its highly relevant in embolization procedures for pseudoaneurysms [13]. Therefore, in the present study, a novel classification system of the different origin types of the IGA was created.

The other branches of the ADIIA are also subjects for embolization procedures, especially the uterine artery. Uterine artery embolization can be performed to prevent or treat bleeding associated with various obstetric conditions, such as postpartum haemorrhage or ectopic pregnancy [9]. Furthermore, uterine fibroids, the most common pelvic tumours in women, acquire their blood supply almost exclusively from the uterine artery [17, 24, 25]. Embolization of uterine arteries reduces the blood supply to the uterus and, with that, reduces the size of fibroids, resulting in decreased pain and dysmenorrhea [14]. Therefore, the morphometric properties of the IGA and the branches of the ADIIA were also analysed.

It is hoped that the results of the present study may give new insights into the complex anatomy of the IGA and the ADIIA, which can ultimately lead to a greater understanding of the vascular anatomy of the pelvis.

MATERIALS AND METHODS

Bioethical Committee

The research protocol was submitted for evaluation and approved by the Bioethical Committee of Jagiellonian University, Krakow, Poland (1072.6120.254.2022). Further stages of the study were carried out in accordance with the approved guidelines.

Study group

A retrospective study was conducted to establish anatomical variations, their prevalence and morphometrical data on IGA and its branches. The results of 75 consecutive patients who underwent pelvic computed tomography angiography (CTA) were analysed. The CTAs were performed in the Department of Radiology of the Jagiellonian University Medical College, Cracow, Poland, between 2017 and 2022. The results of each patient were analysed bilaterally at the Department of Anatomy of the Jagiellonian University Medical College, Krakow, Poland, in August 2022. A total of 150 IGAs were initially evaluated. Exclusion criteria were set as follows: (1) pelvic or abdominal trauma affecting the course of the IGA and/or its initial branches, (2) significant artifacts that prevented accurate and precise imaging and/or measurement of the IGA and/or its initial branches, (3) low quality and illegible images and (4) significant lack of filling the whole arterial system with contrast. Defects, which met the exclusion criteria but included only one side of the CTA, without interference with the contralateral side, did not disqualify the whole CTA but only the affected side. Therefore, of the initial 150, a total of 12 IGAs were excluded due to significant artifacts (n = 5) or a lack of contrast filling (n = 7) in order to minimise possible bias. Finally, 138 IGA of 69 patients met the required criteria.

Acquisition of results

All pelvic CTA were performed on a 128-slice scanner CT (Philips Ingenuity CT, Philips Healthcare). The main CTA imaging parameters were as follows: collimation/increment: 0.625/0.3 mm; tube current: 120 mAs; field of view: 210 mm; matrix size: 512 × 512. All of the patients received intravenous administration of contrast material at a dose of 1 mL/kg (standard dose). A non-ionic contrast medium (CM) containing 350 mg of iodine per mL was used (Jowersol 741 mg/mL, Optiray®, Guerbet, France). CT data acquisition was triggered using a real-time bolus-tracking technique (Philips Healthcare) with the region of interest placed in the ascending aorta. The CM was intravenously injected using a power injector at a flow rate of 5 mL/s. This was immediately followed by the injection of 40 mL of saline solution at the same flow rate. Following injection of CM and saline, image acquisition was automatically started with a 2 s delay when the attenuation trigger value reached a threshold of 120 Hounsfield units (HU). Scanning was performed in the caudocranial direction.

The CTAs were analysed on a dedicated workstation at the Anatomical Department of Jagiellonian University Medical College, Krakow, Poland. To ensure the highest possible quality of the visualizations and measurements and minimize potential bias, Materialise Mimics Medical version 21.0 software (Materialise NV, Leuven, Belgium) software was used. Three-dimensional (3D) reconstructions of each scan were developed, employing a set of settings, severally adjusted to each scan. A volume rendering opacity range oscillated from 25 to 80 HU for the lower limit and up to 3070 HU for a higher limit. The range was individually adjusted to each TT after a visual investigation.

Evaluation and measurements

At the beginning of each evaluation, the authors ensured that each IGA, its branches, and its close anatomical area were fully visualized. Subsequently, each branch of the IGA was identified by following its course. The origin of the IGA and a set of its branches was evaluated with their arrangement and were descriptively noted. Subsequently, a set of measurements was conducted on each IGA and its close anatomical area by two independent researchers, and a mean was established taking into account both results. All measurements were rounded to two decimal places. The following measurements were taken: (1) IGA length [mm]; (2) distance from the origin of the ADIIA to the origin of the IGA [mm]; (3) Distance from the origin of the IIA to the origin of the IGA [mm]; (4) Distance from the origin of the superior gluteal artery (SGA) to the origin of the IGA [mm]; (5) Distance from the origin of the posterior division of the internal iliac artery (PDIIA) to the origin of the IGA [mm]; (6) IGA origin diameter [mm]; (7) IGA origin area [mm2]; (8) IGA origin angle; (9) Obturator artery origin diameter [mm]; (10) Obturator artery origin area [mm2]; (11) Umbilical artery origin diameter [mm]; (12) Umbilical artery origin area [mm2]; (13) Uterine artery origin diameter [mm]; (14) Uterine artery origin area [mm2]; (15) Vaginal artery origin diameter [mm]; (16) Vaginal artery origin area [mm2]; (17) Middle anorectal artery origin diameter [mm]. (18) Middle anorectal artery origin area [mm2]; (19) Internal pudendal artery origin diameter [mm]; (20) Internal pudendal l artery origin area [mm2]; (21) Inferior vesical origin diameter [mm]; (22) Inferior vesical origin area [mm2]; (23) Distance between the origin of the obturator artery and the origin of the IGA [mm]; (24) Distance between the origin of the umbilical artery and the origin of the IGA [mm]; (25) Distance between the origin of the uterine artery and the origin of the IGA [mm]; (26) Distance between the origin of the vaginal artery and the origin of the IGA [mm]; (27) Distance between the origin of the middle anorectal artery and the origin of the IGA [mm]; (28) Distance between the origin of the internal pudendal artery and the origin of the IGA [mm]; (29) Distance between the origin of the inferior vesical artery and the origin of the IGA [mm]. In addition, a set of individual patient parameters such as age and sex were observed.

Statistical analysis

Statistical analysis was performed with SATISTICA v13.1 (StatSoft Inc., Tulsa, OK, USA). The frequencies and percentages presented qualitative features. The Shapiro-Wilk test was used to assess the normal distribution. Quantitative characteristics were presented by medians and higher and lower quartiles (HQ, LQ), as well as means and standard deviation (SD), depending on the verified normality of the data. Statistical significance was defined as p < 0.05. U Mann-Whitney and Wilcoxon signed-rank tests were used to establish potential differences between groups. Spearman’s rank correlation coefficient was used to determine possible correlations between the parameters.

RESULTS

Qualitative results

All subsequent results are presented in relation to the number of IGA instead of number of patients. A total of 138 IGA were analysed. Of these, 78 (56.5%) were from women and 60 (43.5%) were from men. The origin variation of each IGA was deeply analysed. Four origin variations have been observed. Therefore, in response to the literature lacks, a classification method of the IGA origin was set and consists of four main types. Those four main types were set as follows: (1) Type O1 — IGA branches off directly from the ADIIA; (2) Type O2 — IGA branches off directly from the IIA; (3) Type O3 — IGA branches off directly from the SGA; (4) Type O4 — IGA branches off directly from the PDIIA. The most common Type O1 occurred in 86 (62.3%) of the studied cases. All the statistics mentioned above, and more detailed ones can be found in Table 1. Origin types are illustrated on Figure 2.

Table 1. Qualitative results of the data analysis

Category	N	Percentage
Patients’ sex
Females	78	56.5%
Males	60	43.5%
Patients’ side
Left	71	51.4%
Right	67	48.6%
Origin type
Type O1 (ADIIA)	86	62.3%
Type O2 (IIA)	33	23.9%
Type O3 (SGA)	10	7.2%
Type O4 (PDIIA)	9	6.5%

IGA — inferior gluteal artery; ADIIA — anterior division of the internal iliac artery; IIA — internal iliac artery; SGA — superior gluteal artery; PDIIA — posterior division of the internal iliac artery. The four types of origin are established as follows: (1) Type O1 — IGA branches off directly from the ADIIA; (2) Type O2 — IGA branches off directly from the IIA; (3) Type O3 — IGA branches off directly from the SGA; (4) Type O4 — IGA branches off directly from the PDIIA

Figure 2. Origin types of the inferior gluteal artery (IGA); IIA — internal iliac artery; PDIIA — posterior division of the internal iliac artery; ADIIA — anterior division of the internal iliac artery; ILA — iliolumbar artery; SG — superior gluteal artery; LSA — lateral sacral arteries; UA — umbilical artery; OA — obturator artery; IVA — inferior vesicular artery; VA — vaginal artery; UTA — uterine artery; IPA — internal pudendal artery.

Measurements analysis

The median IGA length was set to be 68.50 mm (LQ: 54.29; HQ: 86.06). The median distance from the origin of the ADIIA to the origin of the IGA was set to be 38.22 mm (LQ: 20.22; HQ: 55.97). The median origin diameter of the IGA was established at 4.69 mm (LQ: 4.13; HQ: 5.45). The median origin area of the IGA was found to be 15.16 mm (LQ: 11.00; HQ: 18.84). The detailed results of each category can be found in Table 2.

Table 2. Results of the measurements

Category	Median	LQ	HQ	Minimum	Maximum	Mean	SD
IGA length [mm]	68.50	54.29	86.06	4.26	149.31	71.53	27.43
Distance from the origin of the ADIIA to the origin of the IGA [mm]	38.22	20.22	55.97	6.91	92.48	39.77	23.06
Distance from the origin of the IIA to the origin of the IGA [mm]	63.67	46.74	74.20	13.19	90.10	59.37	18.76
Distance from the origin of the SGA to the origin of the IGA [mm]	37.94	36.17	41.99	14.65	53.30	38.04	10.48
Distance from the origin of the PDIIA to the origin of the IGA [mm]	37.49	19.17	44.55	14.78	53.79	33.87	14.56
IGA origin diameter [mm]	4.69	4.13	5.45	1.83	11.41	4.80	1.08
IGA origin area [mm2]	15.16	11.00	18.84	2.41	36.17	15.59	5.77
IGA origin angle	123.29	86.12	142.27	14.46	178.01	112.78	39.66
Obturator artery origin diameter [mm]	3.13	2.65	3.76	1.42	5.89	3.23	0.87
Obturator artery origin area [mm2]	7.00	4.66	8.64	1.18	15.44	7.00	3.16
Umbilical artery origin diameter [mm]	2.84	2.49	3.52	1.40	5.30	2.94	0.78
Umbilical artery origin area [mm2]	5.66	3.85	9.08	1.21	15.02	6.23	3.10
Uterine artery origin diameter [mm]	3.18	2.45	3.89	1.87	4.70	3.19	0.88
Uterine artery origin area [mm2]	6.30	4.07	8.37	2.10	16.87	6.84	3.57
Vaginal artery origin diameter [mm]	2.67	2.63	3.33	1.90	3.64	2.79	0.56
Vaginal artery origin area [mm2]	4.95	4.66	6.83	2.59	9.85	5.66	2.32
Middle anorectal artery origin diameter [mm]	3.05	2.63	3.43	1.76	4.60	3.05	0.69
Middle anorectal artery origin area [mm2]	5.93	4.69	7.95	1.51	15.32	6.73	3.18
Internal pudendal artery origin diameter [mm]	3.20	2.70	3.85	1.60	6.35	3.28	0.86
Internal pudendal l artery origin area [mm2]	6.74	4.67	9.13	1.30	30.95	7.15	3.64
Inferior vesical origin diameter [mm]	1.84	1.75	2.31	1.14	3.37	2.08	0.83
Inferior vesical origin area [mm2]	2.92	1.86	6.18	1.67	8.56	4.02	3.17
Distance between the origin of the obturator artery and the origin of the IGA [mm]	21.34	9.25	41.88	0.00	77.00	26.53	20.19
Distance between the origin of the umbilical artery and the origin of the IGA [mm]	24.42	11.36	39.85	0.00	74.54	28.18	19.99
Distance between the origin of the uterine artery and the origin of the IGA [mm]	28.09	21.34	31.38	8.29	49.52	26.79	10.85
Distance between the origin of the vaginal artery and the origin of the IGA [mm]	38.21	29.89	40.67	3.06	56.52	33.67	19.64
Distance between the origin of the middle anorectal artery and the origin of the IGA [mm]	59.96	32.25	73.90	0.00	103.62	51.35	27.05
Distance between the origin of the internal pudendal artery and the origin of the IGA [mm]	0.00	0.00	12.99	0.00	44.69	7.80	12.91
Distance between the origin of the inferior vesical artery and the origin of the IGA [mm]	54.16	54.01	54.30	54.01	54.30	54.16	0.21

LQ — lower quartile; HQ — higher quartile; SD — standard deviation; IGA — inferior gluteal artery; ADIIA — anterior division of the internal iliac artery; IIA — internal iliac artery; SGA — superior gluteal artery; PDIIA — posterior division of the internal iliac artery

Sexual dimorphism

Separate statistical analysis has been performed, with respect to the sex of the patient. The results statistically significantly (p < 0.05) differed between sexes in four categories. Those results are gathered in Table 3.

Table 3. Results of the measurements concerning the sex

Category	Sex	Median	LQ	HQ	Minimum	Maximum	Mean	SD	P
IGA length [mm]	Female	73.13	57.10	88.88	14.35	149.31	73.12	28.29	0.38
	Male	67.67	51.42	81.27	4.26	145.60	69.49	26.38
Distance from the origin of the ADIIA to the origin of the IGA [mm]	Female	41.37	25.42	55.97	6.91	92.48	42.74	22.18	0.12
	Male	24.29	15.31	59.48	8.51	85.70	35.31	23.96
Distance from the origin of the IIA to the origin of the IGA [mm]	Female	56.29	44.37	68.99	13.19	87.94	56.69	19.53	0.46
	Male	64.83	47.65	76.53	21.06	90.10	62.05	18.19
Distance from the origin of the SGA to the origin of the IGA [mm]	Female	37.40	31.17	41.63	14.65	49.28	35.25	11.75	0.34
	Male	39.62	36.81	47.65	36.36	53.30	42.23	7.79
Distance from the origin of the PDIIA to the origin of the IGA [mm]	Female	23.34	14.78	37.48	14.78	37.48	25.20	11.46	0.14
	Male	44.01	37.50	45.08	14.99	53.79	39.07	14.66
IGA origin diameter [mm]	Female	4.48	3.92	5.26	1.83	6.73	4.61	0.93	0.01
	Male	4.94	4.37	5.59	3.20	11.41	5.07	1.22
IGA origin area [mm2]	Female	14.57	10.60	18.04	2.41	30.50	15.18	5.83	0.25
	Male	15.32	11.95	18.99	6.46	36.17	16.15	5.68
IGA origin angle	Female	106.74	68.48	134.06	14.46	178.01	105.15	41.98	0.03
	Male	132.26	119.63	146.18	40.40	166.62	127.64	30.48
Obturator artery origin diameter [mm]	Female	3.01	2.56	3.50	1.42	5.89	3.07	0.87	0.00
	Male	3.58	3.11	4.17	1.50	5.18	3.50	0.80
Obturator artery origin area [mm2]	Female	6.32	4.50	7.74	1.18	15.44	6.44	3.06	0.01
	Male	8.28	5.85	9.23	1.50	15.37	7.98	3.14
Umbilical artery origin diameter [mm]	Female	2.85	2.49	3.60	1.40	5.30	3.00	0.82	0.52
	Male	2.82	2.25	3.00	1.61	3.95	2.75	0.64
Umbilical artery origin area [mm2]	Female	5.85	3.96	9.48	1.21	15.02	6.53	3.31	0.46
	Male	5.47	3.74	6.57	1.38	9.87	5.33	2.23
Uterine artery origin diameter [mm]	Female	3.18	2.45	3.89	1.87	4.70	3.19	0.88	–
	Male	–	–	–	–	–	–	–
Uterine artery origin area [mm2]	Female	6.30	4.07	8.37	2.10	16.87	6.84	3.57	–
	Male	–	–	–	–	–	–	–
Vaginal artery origin diameter [mm]	Female	2.67	2.63	3.33	1.90	3.64	2.79	0.56	–
	Male	–	–	–	–	–	–	–
Vaginal artery origin area [mm2]	Female	4.95	4.66	6.83	2.59	9.85	5.66	2.32	–
	Male	–	–	–	–	–	–	–
Middle anorectal artery origin diameter [mm]	Female	3.05	2.63	3.46	1.76	4.60	3.06	0.76	0.93
	Male	3.06	2.61	3.32	2.44	3.69	3.01	0.44
Middle anorectal artery origin area [mm2]	Female	5.93	4.69	8.27	1.51	15.32	6.78	3.45	0.92
	Male	6.47	5.05	7.94	3.05	10.45	6.55	2.29
Internal pudendal artery origin diameter [mm]	Female	3.02	2.48	3.80	1.60	5.42	3.21	0.95	0.15
	Male	3.36	2.95	3.85	2.02	6.35	3.38	0.73
Internal pudendal l artery origin area [mm2]	Female	6.30	4.18	9.04	1.30	14.34	6.72	3.29	0.11
	Male	7.11	5.70	9.13	2.83	30.95	7.78	4.05
Inferior vesical origin diameter [mm]	Female	–	–	–	–	–	–	–	–
	Male	2.08	1.80	2.84	1.75	3.37	2.32	0.74
Inferior vesical origin area [mm2]	Female	–	–	–	–	–	–	–	–
	Male	2.92	1.86	6.18	1.67	8.56	4.02	3.17
Distance between the origin of the obturator artery and the origin of the IGA [mm]	Female	24.07	9.25	42.32	0.00	77.00	27.83	20.65	0.57
	Male	16.87	9.22	41.88	0.00	58.89	23.87	19.37
Distance between the origin of the umbilical artery and the origin of the IGA [mm]	Female	26.00	11.51	39.85	5.44	74.54	28.79	19.06	0.59
	Male	19.71	8.17	43.91	0.00	71.94	26.44	23.23
Distance between the origin of the uterine artery and the origin of the IGA [mm]	Female	28.09	21.34	31.38	8.29	49.52	26.79	10.85	–
	Male	–	–	–	–	–	–	–
Distance between the origin of the vaginal artery and the origin of the IGA [mm]	Female	38.21	29.89	40.67	3.06	56.52	33.67	19.64	–
	Male	–	–	–	–	–	–	–
Distance between the origin of the middle Anorectal artery and the origin of the IGA [mm]	Female	60.54	35.91	73.90	6.78	90.28	52.99	23.47	0.64
	Male	46.11	14.11	74.62	0.00	103.62	46.66	37.02
Distance between the origin of the internal pudendal artery and the origin of the IGA [mm]	Female	0.00	0.00	6.89	0.00	44.69	6.15	11.79	0.19
	Male	0.00	0.00	20.54	0.00	43.29	10.63	14.42
Distance between the origin of the inferior vesical artery and the origin of the IGA [mm]	Female	–	–	–	–	–	–	–	–
	Male	54.16	54.01	54.30	54.01	54.30	54.16	0.21

LQ — lower quartile; HQ — higher quartile; SD — standard deviation; IGA — inferior gluteal artery; ADIIA — anterior division of the internal iliac artery; IIA — internal iliac artery; SGA — superior gluteal artery; PDIIA — posterior division of the internal iliac artery

Correlations

Potential associations between each category and patient’s age was demonstrated. Three categories statistically significantly correlate with patient’s age. The R values obtained in the correlation analysis between the groups can be found in Table 4. Highlighted in red are those in which the p-value was less than 0.05.

Table 4. Correlations between the measured parameters of the inferior gluteal artery (IGA) and patient’s age

Category	Age	IGA length [mm]
IGA length [mm]	–0.08	1.00
Distance from the origin of the ADIIA to the origin of the IGA [mm]	0.32	–0.37
Distance from the origin of the IIA to the origin of the IGA [mm]	0.09	–0.01
Distance from the origin of the SGA to the origin of the IGA [mm]	0.46	–0.30
Distance from the origin of the PDIIA to the origin of the IGA [mm]	0.34	–0.33
IGA origin diameter [mm]	0.02	–0.04
IGA origin area [mm2]	0.04	0.07
IGA origin angle	–0.06	–0.27
Obturator artery origin diameter [mm]	–0.08	–0.36
Obturator artery origin area [mm2]	–0.07	–0.31
Umbilical artery origin diameter [mm]	0.02	–0.19
Umbilical artery origin area [mm2]	0.02	–0.15
Uterine artery origin diameter [mm]	–0.32	0.08
Uterine artery origin area [mm2]	–0.29	0.16
Vaginal artery origin diameter [mm]	–0.32	0.00
Vaginal artery origin area [mm2]	–0.29	–0.05
Middle anorectal artery origin diameter [mm]	–0.22	–0.05
Middle anorectal artery origin area [mm2]	–0.09	0.03
Internal pudendal artery origin diameter [mm]	–0.08	–0.15
Internal pudendal l artery origin area [mm2]	–0.05	–0.06
Inferior vesical origin diameter [mm]	0.67	0.70
Inferior vesical origin area [mm2]	0.95	0.80
Distance between the origin of the obturator artery and the origin of the IGA [mm]	0.28	–0.33
Distance between the origin of the umbilical artery and the origin of the IGA [mm]	0.21	–0.45
Distance between the origin of the uterine artery and the origin of the IGA [mm]	0.25	0.44
Distance between the origin of the vaginal artery and the origin of the IGA [mm]	0.97	–0.10
Distance between the origin of the middle anorectal artery and the origin of the IGA [mm]	0.13	0.70
Distance between the origin of the internal pudendal artery and the origin of the IGA [mm]	–0.01	0.04

Highlighted in red are those in which the p-value was less than 0.05. IGA — inferior gluteal artery; ADIIA — anterior division of the internal iliac artery; IIA — internal iliac artery; SGA — superior gluteal artery; PDIIA — posterior division of the internal iliac artery. R — Spearman’s rank correlation coefficient

Side differences

Subsequently, potential differences in the measured parameters, occurrence of origin types and cooccurrence of types with respect to the patient’s side have been analysed. The detailed results can be found in Table 5.

Table 5. Comparison between patient’s side

Occurrence of IGA origin type with respect to the patient’s side
Category	Left side					Right side
Type O1 (ADIIA)	42 (59.2%)					44 (65.7%)
Type O2 (IIA)	22 (31.0%)					11 (16.4%)
Type O3 (SGA)	3 (4.2%)					7 (10.4%)
Type O4 (PDIIA)	4 (5.6%)					5 (7.5%)
Cooccurrence of SGA origin types
Cooccurrence	Origin type on the right side
			Type O1 (ADIIA)		Type O2 (IIA)		Type O3 (SGA)		Type O4 (PDIIA)
Origin type on the left side	Type O1 (ADIIA)		31 (46.3%)		2 (3.0%)		5 (7.5%)		3 (4.5%)
	Type O2 (IIA)		11 (16.4%)		9 (13.4%)		0 (0.0%)		1 (1.5%)
	Type O3 (SGA)		1 (1.5%)		0 (0.0%)		2 (3.0%)		0 (0.0%)
	Type O4 (PDIIA)		1 (1.5%)		0 (0.00%)		0 (0.0%)		1 (1.5%)
Comparison of selected parameters with respect to the patient’s side
Category		Side	Median	LQ	HQ	Minimum	Maximum	Mean	SD	P
IGA length [mm]		Left	71.53	57.10	81.66	14.35	149.31	72.47	26.08	0.75
		Right	66.52	52.37	88.57	4.26	145.60	70.55	28.94
Distance from the origin of the ADIIA to the origin of the IGA [mm]		Left	30.57	18.63	55.66	6.91	92.48	38.07	23.35	0.50
		Right	39.69	22.41	60.38	8.44	85.70	41.35	22.94
Distance from the origin of the IIA to the origin of the IGA [mm]		Left	65.74	49.35	73.18	21.06	90.10	61.54	17.39	0.48
		Right	59.10	39.58	77.84	13.19	81.81	55.22	21.39
Distance from the origin of the SGA to the origin of the IGA [mm]		Left	39.08	36.17	41.99	36.17	41.99	39.08	4.12	0.90
		Right	37.94	33.77	45.46	14.65	53.30	37.78	11.77
Distance from the origin of the PDIIA to the origin of the IGA [mm]		Left	44.55	29.40	49.44	14.78	53.79	39.42	17.00	0.31
		Right	30.41	19.17	37.49	14.99	37.50	28.33	11.12

LQ — lower quartile; HQ — higher quartile; SD — standard deviation; IGA — inferior gluteal artery; PDIIA — posterior division of the internal iliac artery; ADIIA — anterior division of the internal iliac artery; IIA — internal iliac artery; SGA — superior gluteal artery

DISCUSSION

The present study is the first to thoroughly analyse the anatomy of the IGA using CTA. With the data gathered from the acquired imaging studies, a novel classification system of the origin of the said artery was created. Our classification system consists of four different types: type 1 represents the most frequent origin pattern, namely, the IGA originating directly from the ADIIA (O1: 62.3%). Next, type 2 presents the IGA originating directly from the IIA before it bifurcates into its anterior and posterior trunks (O2: 23.9%). Type 3 represents the IGA arising from the superior gluteal artery (O3: 7.2%). Lastly, type 4 describes the IGA as originating from the PDIIA (O4: 6.5%). This is the most in-depth analysis performed concerning the origin of the IGA in the available literature. Our data shows that the IGA originates most frequently from the ADIIA, fitting the description provided by the major anatomical textbooks [15]. However, our results show also that the IGA is subject to a relatively high degree of variability.

Although rare, aneurysms of IGA may occur. Kuzuya et al. [13] presented a case report about a 78-year-old patient presenting with painful swelling in the right buttock. There was no history of trauma or infection, and the patient was undergoing antiplatelet therapy. Arteriography demonstrated a pseudoaneurysm arising from the right IGA. The treatment consisted of a transluminal coil embolization by ultrasound-guided direct puncture of the IGA. The catheter was successfully advanced to the proximal side of the pseudoaneurysm and occluded with two coils. This proves the importance of having adequate knowledge about the anatomy of the IGA.

The IGA perforator flap has been used in both reconstructions of the gluteal region, but also breast reconstructive procedures [1, 11]. Because of the clinical significance of this vessel, its anatomy has been extensively researched in the past. Georgantopoulou et al. [4] analysed the microvascular anatomy of the SGA and IGA perforator flaps. In the study, it was stated that the location of the IGA perforators was less definite and varied considerably. Interestingly, Vigato et al. [23] stated that the gluteal region was vascularized by perforators of multiple source arteries, not only from the IGA and SGA. Furthermore, in another anatomical and radiological study conducted by Song et al. [20] on the anatomy of the IGA and SGA, the IGA was found to be absent in 13.5% of cases. We did not note this happening in our analysis.

Surgeons should always be aware of detailed anatomical knowledge about the IGA and its close area should when performing augmentation gluteoplasty with a dermal fat flap [8, 21]. The key to performing gluteal augmentation safely and minimising risk and complications is to truly know the anatomy of the gluteal area [8].

The relation and course of the IGA to the sciatic nerve and the sacrospinous ligament have also been extensively discussed in the literature. Gabrielli et al. [3] stated that the IGA was found medial to the sciatic nerve in the majority of the cases (77.5%), and in the rest of the cases (22.5%), the main trunk of the artery or one of its branches perforated the said nerve. The anatomy of the pelvic arteries adjacent to the sacrospinous ligament was discussed in a study conducted by Thompson et al. [22]. In the study, the IGA was found behind the sciatic nerve and the sacrospinous ligament when originating from either the ADIIA or PDIIA. When it was leaving the pelvis, the artery passed posterior to the upper edge of the said ligament and followed the inferior portion of the sciatic nerve out of the greater sciatic foramen. Knowledge about this region is particularly important when putting sutures through the sacrospinous ligament during various obstetric and gynaecological surgeries in the pelvis.

The IGA contributes to the blood supply of the hip through the anastomosis with the medial femoral circumflex artery. This phenomenon has been extensively described by Grose et al. [5] in a cadaveric study consisting of eight fresh-frozen cadaver pelvis specimens. They concluded that the medial circumflex artery receives a direct blood supply from the IGA immediately before passing beneath the hip capsule. A precise understanding of the vascular anatomy of this region may help to clarify the development of avascular necrosis after hip trauma.

Having extensive knowledge regarding the arterial anatomy of the pelvis may be of immense importance during numerous pelvic operations, especially interventional intraarterial procedures [10]. Embolization of the uterine artery can be performed to prevent or treat haemorrhage associated with numerous obstetric conditions, such as postpartum bleeding or ectopic pregnancy [9]. Postpartum haemorrhage accounts for up to 25% of maternal deaths worldwide [19], and the main treatment option is said to be embolization of the uterine artery. However, embolization of the said vessel may be challenging due to its variable anatomy. Therefore, Ostrowski et al. [16] analysed the complete anatomy of this artery in a meta-analysis consisting of over 2000 subjects. In the study, it was stated that the knowledge about the morphometric values of the uterine artery (UTA) specifically its diameter is of great importance when choosing an appropriately-sized catheter for embolization procedures. The meta-analysis showed that the mean diameter of the uterine artery was 2.74 mm. Our study presents a slightly higher median diameter of 3.18 mm. Another branch of the ADIIA, the middle anorectal artery, is also highly variable. The said artery is also important to interventional radiologists who might embolize this vessel as a treatment for rectal bleeding [6]. Pichon et al. [18] presented two successful cases of this technique, where the aetiology of the bleeding was trauma to the rectum. We found the external diameter of the middle anorectal artery to be 3.05 mm, which is considerably higher than what was reported in other studies in the literature [2, 7].

Limitations of the study

The present study undoubtedly has some limitations. Although the size of the study group used in the current paper is the largest among imaging studies regarding IGA, larger population-based research is still warranted to discern the true prevalence of its variants. Furthermore, radiological imaging only allows one to evaluate haemodynamically efficient arteries. Therefore, this can be a relatively large source of bias when assessing anatomical variations of the IGA and other arterial entities. The particular branches of the IGA and their anastomosis with surrounding vascular structures should be further investigated in the future due to their potential clinical significance in endovascular and orthopaedic procedures.

CONCLUSIONS

The present study thoroughly analysed the complete anatomy of the IGA and the branches of the ADIIA. A novel classification system for the origin of the IGA was created, where the most prevalent origin was from the ADIIA (type 1; 62.3%). Furthermore, the morphometric properties (such as the diameter and length) of the branches of the ADIIA were analysed. This data may be incredibly useful for physicians performing operations in the pelvis, such as interventional intraarterial procedures or various gynaecological surgeries.

Figure 3. Anterior view of the analysed computer tomography angiography. Some of the arteries were shortened and/or excluded in order to provide clearest possible view; CIA — common iliac artery; IIA — internal iliac artery; EIA — external iliac artery; OA — obturator artery; UA — umbilical artery; IGA — inferior gluteal artery; MRA — middle rectal artery; IVA — inferior vesical artery.

Figure 4. Posterior view of the analysed computer tomography angiography. Some of the arteries were shortened and/or excluded in order to provide clearest possible view; IGA — inferior gluteal artery; SGA — superior gluteal artery; OA — obturator artery; IVA — inferior vesical artery.