ORIGINAL ARTICLE

Modified Medial Stoppa Approach For Acetabular Fractures:
An Anatomic Study

Burkay Kutluhan Kacıra, MD, Mehmet Arazi, MD, Aynur Emine Cicekcibasi, MD, Mustafa Büyükmumcu, PhD,
and Serafettin Demirci, MD

Background: The modified medial Stoppa approach is an alternative and
new surgical approach to access to the internal pelvis and medial wall of the
acetabulum. There is little information about the clinical anatomic specifi-
cations of exposure in the literature. In this study, the pertinent surgical
anatomy that involved the modified medial Stoppa approach was further
defined and the anatomic positions and variations of the structures seen in the
surgical site were analyzed.
Methods: We dissected five formalized cadavers to present structures at risk
in a standard modified medial Stoppa approach. The internal iliac artery and
branches were colored with latex injection in formalized cadavers. Morpho-
metrical measurements of the neurovascular structures adjacent to quadrilat-
eral surface and their anatomic variations were noted.
Results: It was detected that the obturator vessels and nerve and the
iliolumbar vessels were primarily the structures at risk. Obturator vessels and
nerve were the most important structures to pay attention because of their
direct contact to quadrilateral surface. There was communication (corona
mortis) between obturator and inferior epigastric veins in 4 (40%) of 10
hemipelvises.
Conclusions: Before clinical applications, performing cadaver dissection is
important to minimize intraoperative complications. This study was the first
anatomic study in the literature that reveals the structures that are at risk
during surgical treatment of acetabular fractures, which was treated with the
modified medial Stoppa approach.
Key Words: Modified medial Stoppa approach, Cadaver, Anatomy.

(J Trauma. 2011;71: 1340–1344)

Displaced acetabular fractures are best treated by open
reduction and internal fixation like any other intra-

articular fractures. Many studies have indicated that late
traumatic osteoarthrosis is lowered by a successful operative
reduction.1–5 The main obstacle to reduction in a severely
displaced acetabular fracture is easy access to the fracture site

and good visualization of the surrounding structures. Both
extensile and nonextensile exposures can be used for surgical
approach, the Kocher-Langenbeck, ilioinguinal, and extended
iliofemoral being the most common. Although extensile ex-
posures provide clear visualization, they have resulted in
higher complication rates and more morbidity than nonexten-
sile exposures. When choosing a surgical approach, the least
invasive approach that allows effective reduction and fixation
of the acetabulum fractures should be preferred.

Originally used for hernia repair and surgery, the re-
cently modified medial Stoppa approach has also been used
for the treatment of pelvic and acetabular fractures as a
nonextensile exposure.6–9 This approach provides access to
the medial wall of the acetabulum, quadrilateral surface, and
sacroiliac joint and may be an alternative to the commonly
used approaches. The modified medial Stoppa approach was
first described by Hirvensalo et al.10 and later by Cole and
Bolhofner11 as a new technique in orthopedic surgery for
fractures of the anterior column or wall, transverse fractures,
T-type fractures, both column fractures and fractures of the
anterior wall, or the column associated with posterior hemi-
transverse fractures.6,7,10–12

The number of clinical studies investigating fractures
treated with this approach is limited, and also there is little
information about the long-term results. Moreover, there are
no relevant clinical anatomic studies in the literature. This
study aimed to investigate the anatomic structures in the
surgical field, the positions, and variations of these structures
and to further define the pertinent surgical anatomy involved
in the modified medial Stoppa approach. The hypotheses
questioned in this study were as follows:

1. Which anatomic structures frequently constrain the ap-
plication of this approach and what are their precise
locations?

2. Do neurovascular structures in the region have variations
that increase the difficulty of surgical dissection and
thereby surgical operation?

3. What is the applicability of this approach in orthopedic
surgery?

MATERIALS AND METHODS
This study conformed to the Helsinki Declaration. Five

formalized cadavers (3 men and 2 women) were dissected to
analyze their anatomic structures in the intrapelvic area and
the localization and variations of these structures. The mod-

Submitted for publication August 5, 2010.
Accepted for publication November 29, 2010.
Copyright © 2011 by Lippincott Williams & Wilkins
From the Department of Orthopedics and Traumatology (BKK), Meram Medical

Faculty, Selcuk University, Konya; Department of Orthopedics and Trauma-
tology (MA), Farabi Klinik, Konya; Department of Anatomy (AEC, MB),
Meram Medical Faculty, Selcuk University, Konya; and Department of
Forensic Medicine (SD), Meram Medical Faculty, Selcuk University, Konya,
Turkey.

Presented as a poster at the 10th EACA Congress, September 2–5, 2009, Istanbul,
Turkey.

Address for reprints: Aynur Emine Cicekcibasi, MD, Department of Anatomy,
Meram Medical Faculty, Selcuk University, 42080 Meram, Konya, Turkey;
email: aynurcicekcibasi@yahoo.com.tr.

DOI: 10.1097/TA.0b013e3182092e8b

1340 The Journal of TRAUMA® Injury, Infection, and Critical Care • Volume 71, Number 5, November 2011



ified medial Stoppa approach defined by Cole and Bol-
hofner11 was applied. An incision over the external ring was
made horizontally from 2 cm proximal to the pubic symphy-
sis. The rectus abdominis muscles were separated vertically
and liberated by cutting from the pubic adhesions. In the
suprapubic region, the bladder was observed in the retro-
peritoneal area. Dissection continued from the retroperito-
neum sighting and retracting the external iliac artery and
below the femoral nerve. The iliopectineal fascia and
periosteum were released by sharp dissection to access the
internal part of the pelvis. By suspending the iliopsoas
muscle, the iliopectineal line was revealed. This approach
provided access to the internal part of the pelvis from the
pubic symphysis to the sacroiliac joint. The location of the
quadrilateral surface was determined by locating the sci-
atic notch and obturator foramen. The neurovascular struc-
tures related to the quadrilateral surface and iliopectineal
line were detected (Fig. 1).

First, to observe the common iliac artery and its
branches properly, a detailed dissection was performed,
and latex was injected into the vessels. The common iliac
artery was cut 1 cm to 2 cm distal from the bifurcation of
the aorta, liberating the end of the vessel into which a scalp
vein set was inserted and the needle fixed by suture
ligation over the vessel. Before the latex injection, the
vessel was washed with physiologic serum several times to
decrease intravascular congestion and coagulum. To in-
crease the fluidity of the latex, a viscous solution com-
monly used in cadaver studies, which was diluted with
25% distilled water, and a homogeneous colored solution
was prepared using red China ink. The prepared latex
solution was injected slowly into the vessel with the scalp
vein set, and when pressure occurred, the injection was
discontinued for some time to allow the distribution of
latex within the vessel. When the injection was completed,
the scalp vein set was removed slowly, and the common
iliac artery was ligated immediately. To allow fixation of

the latex, the material was kept at room temperature for 24
hours after which all the hemipelvises were dissected, and
morphometric measurements were performed. All cadav-
ers were placed in the supine position, and gross and
microdissection techniques were used. The neurovascular
structures related to the quadrilateral surface and ili-
opectineal line were observed. The dimensions in their
original anatomic structures were measured using an elec-
tronic caliper (Best 150 � 0.01 mm) and flexible ruler. In
addition, microdissection tools and the microsurgery mi-
croscope were used. To minimize the risk of error during
these steps, all steps were performed by the same investi-
gator (B.K.K.).

RESULTS
The course of the obturator vessels and nerve was

examined in detail because of their direct relationship with
the quadrilateral surface. It was observed that the obturator
artery originating from internal iliac artery, together with the
obturator vein to which it was superior, entered the canal
almost parallel to the iliopectineal line (Fig. 2).

In both hemipelvises of one cadaver, it was observed
that the obturator artery originating from the inferior epigas-
tric artery crossed the pubic ramus and then directly entered
the obturator canal (Fig. 3). In two hemipelvises, it was
observed that a second obturator vein originating from the
external iliac vein directly entered the obturator canal by
crossing the iliopectineal line (Fig. 4). Measurements con-
cerning the sources of the obturator artery and vein are
presented in Table 1 (Fig. 5).

The obturator nerve originating from the lumbar
plexus directs to the obturator canal by crossing the ili-
opectineal line close to sacroiliac joint. The mean distance
of the point where the obturator nerve crossed the ili-
opectineal line to the sacroiliac joint was 17.7 mm (11.1–
30.0 mm) on the right and 22.4 mm (10.1– 40.0 mm) on the
left. The mean distance from the point where the obturator

Figure 1. The relation of the obturator canal with the bone
structures. (A) The distance between linea terminalis (iliopectin-
eal line) and obturator canal. (B) The distance between pubic
symphysis and obturator canal. LT, linea terminalis; OC, obtu-
rator canal; and PS, pubic symphysis.

Figure 2. The normal course of the obturator artery, vein,
and nerve. LT, linea terminalis (iliopectineal line); ON, obtu-
rator nerve; OA, obturator artery; OV, obturator vein; and
OC, obturator canal.

The Journal of TRAUMA® Injury, Infection, and Critical Care • Volume 71, Number 5, November 2011 Stoppa Approach for Acetabular Fractures

© 2011 Lippincott Williams & Wilkins 1341



nerve entered the obturator canal to the iliopectineal line
was 18.8 mm (Table 2).

In 4 (40%) of 10 hemipelvises dissected, there was
communication (corona mortis) between the obturator and
inferior epigastric vessels. Half of these communications
were venous only, whereas there were both arterial and
venous communications in the other half (Fig. 6).

The iliolumbar artery originates from the posterior
division of the internal iliac artery. It ascends from the
posterior of the obturator nerve and then lies along the medial
surface of the psoas muscle and crosses the iliopectineal line
(Fig. 7). It is often separated into two branches, the lumbar

and the iliac, supplying the psoas muscle and the iliacus
muscle, respectively. There was no iliolumbar artery in one
(10%) and no iliolumbar veins in four (40%) of the hemipel-
vises dissected. Although five (50%) of the iliolumbar arter-
ies separated into two branches, it was observed that four
(40%) separated into three branches. Although no branching
of the iliolumbar vein was observed in four (40%) of the
pelvises, two (20%) separated into two branches. The dis-
tances of the points where the iliolumbar artery and vein

Figure 3. The variation of the obturator artery. IEA, inferior
epigastric artery; EIA, external iliac artery; EIV, external iliac
vein; OA, obturator artery; ON, obturator nerve; and OC,
obturator canal.

Figure 4. The accessory obturator vein. EIA, external iliac
artery; EIV, external iliac vein; OA, obturator artery; OV, ob-
turator vein; ON, obturator nerve; OC, obturator canal; and
AOV, accessory obturator vein.

TABLE 1. Measurements Regarding Obturator Artery and
Vein

Obturator
Artery

Obturator
Vein

Right Left Right Left

Mean length of vessels (mm) 52.9 58.1 49.3 49.3

The distance from the obturator
canal entrance to linea
terminalis (mm)

22.8 22.9 20.1 22.9

The distance from the root to
linea terminalis (mm)

14.6 25.9 24.7 34.0

The distance from the midpoint
to linea terminalis (mm)

16.0 21.3 20.9 29.2

The distance from the midpoint
to linea terminalis by
retraction (mm)

29.1 28.5 33.7 38.5

Figure 5. The measurements concerning obturator artery.
(A) In the place where the root reveals the distance to linea
terminalis (iliopectineal line). (B) The distance from the mid-
dle point to linea terminalis. (C) In the obturator canal en-
trance, the distance to linea terminalis. (D) Length of the
obturator artery. LT, linea terminalis; PS, pubic symphysis;
OA, obturator artery; OV, obturator vein; ON, obturator
nerve; and OC, obturator canal.

TABLE 2. Measurements Regarding Obturator Nerve

Obturator Nerve

Right Left

The distance to linea terminalis at the
obturator canal entrance (mm)

19.0 18.7

The distance from the intersection point of
linea terminalis to sacroiliac joint (mm)

17.7 22.4

Maximum distance to linea terminalis by
retraction (at the intersection point)

13.5 12.7

Kacıra et al. The Journal of TRAUMA® Injury, Infection, and Critical Care • Volume 71, Number 5, November 2011

© 2011 Lippincott Williams & Wilkins1342



branches intersected the iliopectineal line to the sacroiliac
joint were also measured (Table 3).

DISCUSSION
Although intrapelvic approaches for the treatment of

acetabular fractures have the advantages of providing a
wide surgical field, easy postoperative rehabilitation, and a
low rate of heterotopic ossification, the learning curve is
quite sharp because of many critical anatomic structures in
the surgical field.2,11,13 The ilioinguinal approach, which is
commonly used within intrapelvic approaches, is per-

formed by surgeons having a certain level of experience
because it necessitates dissection of neurovascular struc-
tures and the regions surrounding these structures. To
facilitate this surgical technique and to provide easy access
to the medial wall of the acetabulum, the approach has
been modified by several researchers.1,14

Significant complications such as deep infection, limi-
tations of the movements of the hip joint, heterotopic ossifi-
cation, nonunion of the trochanter major osteotomies, and late
avascular necrosis are commonly addressed with extensile
exposures. The modified medial Stoppa approach provides
reduction and fixation opportunity in fractures with medial
displacement and has a low complication rate. Nevertheless,
the complex anatomy of the surgical field requires careful
study. Researchers who have used the modified medial
Stoppa approach report that in surgical treatment of acetab-
ular fractures related to the quadrilateral surface, adequate
reduction and fixation can be provided by the approach
together with infrapectineal plating, especially in cases with
medial displacement of the femoral head.6,7,10,11

In several studies investigating acetabular fractures,
the anatomic structures in the surgical region have been
described; however, there are very few detailed anatomic
studies concerning these structures. Most clinical anatomic
studies are mainly concerned with bone structure15,16; but
in this study, we aimed to further define the pertinent
surgical anatomy involved in the modified medial Stoppa
approach and to obtain a detailed anatomic measurement of
vascular and neural structures related to the bony surfaces.
Because the obturator vessels and nerve are in close proxim-
ity to the quadrilateral surface and are the anatomic structures
that must be considered in the modified medial Stoppa ap-
proach, these structures have been examined comprehen-
sively in this study. A clinically important variation of the
obturator artery was observed in two (20%) of the hemipel-
vises. In these particular cadavers, the obturator artery orig-
inating from the inferior epigastric artery crossed the pubic
ramus and then directly entered the obturator canal. Gilroy
et al.17 investigated 105 hemipelvises and reported that ob-
turator vessels had variations in 82%.

In 40% of the dissected hemipelvises in this study, com-
munication existed between the obturator and inferior epigastric
vessels. These communications were first defined by Haller in
1745.17 The variations or vascular anastomoses were named
“corona mortis.” Berberoglu et al.18 examined the findings of
both cadaver dissection and laparoscopy and reported venous
communication as 96%. Okcu et al.19 reported a 61% incidence
of corona mortis in 150 hemipelvises. Drewes et al.20 reported
this ratio as 66.7%. In the studies conducted, communications
were observed to be commonly venous. Darmanis et al.21 found
vascular anastomosis in 83% of cadaveric specimens. They
observed that 60% of these anastomotic vessels had a large
diameter (3 mm). However, they reported only five cases with
abnormal vascular communication in a total number of 492
cases in a clinical setting.21 The extension of plates used during
the treatment of acetabulum fractures with intrapelvic ap-
proaches to the pubic ramus allows the careful examination of

Figure 6. The venous communication between inferior epi-
gastric vein and obturator vein “corona mortis.” EIA, exter-
nal iliac artery; EIV, external iliac vein; OA, obturator artery;
OV, obturator vein; ON, obturator nerve; VC, venous com-
munication (red arrows); and IEV, inferior epigastric vein.

Figure 7. Iliolumbar vessels and obturator nerve. Il.V, ilio-
lumbar vein; Il.A, iliolumbar artery; and ON, obturator nerve.

TABLE 3. The Distance From the Point Where Iliolumbar
Artery and Vein Intersected the Linea Terminalis to Sacroiliac
Joint

Iliolumbar Artery Iliolumbar Vein

First
Branch

Second
Branch

Third
Branch

First
Branch

Second
Branch

The distance from the
intersection point of
linea terminalis to
sacroiliac joint (mm)

0.1 6.4 21 11.4 15.3

The Journal of TRAUMA® Injury, Infection, and Critical Care • Volume 71, Number 5, November 2011 Stoppa Approach for Acetabular Fractures

© 2011 Lippincott Williams & Wilkins 1343



these common vascular structures with a high risk of bleeding in
if injured by orthopedists.

The obturator nerve is an important neural structure that
should be considered during intrapelvic approaches. Al-
though the incidence of the accessory obturator nerve is
reported between 8% and 29%, in this study we found no
variations concerning accessory obturator nerve and its
course. Because the obturator nerve directs to the obturator
canal by crossing the iliopectineal line, the risk of injury
increases during plate applications. In this study, this inter-
section was �20.0 mm distant from the sacroiliac joint. At
that point, the nerve was distracted only 13.1 mm from the
iliopectineal line by retraction. Locher et al.22 measured the
distance between the obturator nerve and the anterior border
of the superior ramus of the pubis on the sagittal plane. This
measurement provides information on the depth of the obtu-
rator nerve after the bone has been contacted by the needle
when performing an obturator nerve block. The distance was
2.0 cm (min 1.5 cm, max 2.8 cm). In this study, the distances
to the iliopectineal line at the obturator canal entrance for the
right and left obturator nerve were observed as 19.0 mm and
18.7 mm, respectively. In clinical situations, this distance
may be shorter because soft tissues are tighter in vitro and the
nerve may be injured by rough retraction. In the obturator
canal entrance, the obturator nerve was observed to be the
closest structure to the iliopectineal line (Fig. 2). Although
the obturator artery and vein could be distracted from the
iliopectineal line by retraction at their midpoints, the distance
to the canal entrance did not change. This necessitates careful
application of plates, at the level of the obturator canal.

Because of their close proximity to the iliopectineal line,
the iliolumbar artery and vein are clinically important anatomic
structures. Jasani and Jaffray23 emphasized that in lumbar spine
surgery the iliolumbar vein should be dissected carefully and
ligated in anterior approaches. There was no iliolumbar artery in
10% of the hemipelvises dissected in this study and there was no
vein in 40%. Because of the close proximity of the iliolumbar
vessels to the sacroiliac joint, there may be serious bleeding in
cases of extension of the plates to the sacroiliac joint unless they
are carefully dissected and ligated. The obturator nerve, iliolum-
bar artery, and vein cross each other and the iliopectineal line is
in close proximity to the sacroiliac joint (Fig. 7). Thus, they are
important anatomic structures to consider not only in fractures of
the acetabulum but also in separations of the sacroiliac joints.

This study confirmed the feasibility and applicability of
the exposure of the acetabulum regarding anatomic relation-
ships. The strength of the study was in performing the latex
injection into the arterial structures, which provided precise
evaluation of these structures. The main limitations of this
study were the small number of cadavers, the use of formal-
ized cadavers, and the measurements were done on intact
acetabula. However, to the best of the authors’ knowledge,
this is the first anatomic study of its kind and it will encourage
us to use this technique on patients.

This study showed that obturator vessels and nerve are
the most important structures requiring attention because of
their direct relation with quadrilateral surface. It was also
observed that complete distraction of these structures from

the surgical site by retraction is not entirely possible. Because
the modified medial Stoppa approach necessitates studying a
surgical field with important anatomic structures on the in-
ternal surface of pelvis, performing cadaver dissection before
clinical applications is most valuable to minimize intraoper-
ative complications.

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© 2011 Lippincott Williams & Wilkins1344