Download Relationship Between the Superior Gluteal Vessels and

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Relationship Between the Superior Gluteal
Vessels and Nerve at the Greater Sciatic
Notch
Cory A. Collinge, MD; Navid M. Ziran, MD; David A. Coons, DO
abstract
Bleeding from the superior gluteal (SG) blood vessels at the greater sciatic notch is frequently encountered during acetabular fracture surgery. The purpose of this study is to
define the positional anatomy of the superior gluteal vessels and nerve (SGVAN) at the
greater sciatic notch. Twenty-three hemipelvi were dissected in whole human cadavers.
The greater sciatic notch and SGVAN were visualized via a posterior surgical approach,
identified deep in the greater sciatic notch, and traced superficially. Branches of the
SGVAN and their anatomical relationship to each other were recorded. In the notch,
SG arteries comprised a single vessel in 18 (78%) of 23 specimens, with all of these
dividing at varying distances (1-3.5 cm) along the lateral ilium after dividing into
superior and inferior branches. The SG artery branches were contiguous with periosteum of the bony notch in all specimens. More than 1 SG nerve branch was seen
in the greater sciatic notch of all specimens, including an inferior branch that exited
caudal or caudal-superficial to the SG vessels. The caudal-most SG nerve branch
was directly adjacent to the bony notch’s periosteum in 15 (65%) of 23 specimens.
The SGVAN are at risk in patients undergoing acetabular fracture surgery. Individuals
performing surgery along the acetabulum’s posterior column would expect to encounter a major SG nerve branch (deep inferior) before encountering the SG vessels
in all cases. Iatrogenic injuries to the SGVAN might be prevented by avoiding use of
cautery in this area if hemorrhage is encountered. [Orthopedics. 2015; 38(10):e929e933.]
The authors are from the Department of Orthopedic Surgery (CAC), Vanderbilt University, Nashville, Tennessee; the Hip & Pelvis Institute (NMZ), Saint John’s Health Center, Santa Monica, California; and MultiCare Orthopedics & Sports Medicine (DAC), Tacoma, Washington.
Drs Ziran and Coons have no relevant financial relationships to disclose. Dr Collinge is a paid consultant for Biomet, Stryker, and Smith & Nephew and receives royalties from Biomet, Smith & Nephew,
Advanced Orthopedic Solutions, and Synthes.
Correspondence should be addressed to: Cory A. Collinge, MD, Vanderbilt University Medical Center, MCE-South Tower, Ste 4200, Nashville, TN 37232 ([email protected]).
Received: September 11, 2014; Accepted: January 6, 2015.
doi: 10.3928/01477447-20151002-62
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T
he origin and the intra- and
extra-pelvic anatomy of the superior gluteal (SG) nerve and vessels have been well described.1-7 The SG
artery is the largest branch of the internal
iliac artery, exiting the pelvis through the
greater sciatic notch above the piriformis
and ultimately branching to provide blood
supply to the posterior abductors, including the gluteus medius and minimus, and
ultimately connecting with the femoral
system more anteriorly. The SG veins are
venae comitantes of the superior gluteal
artery; they receive tributaries from the
buttock closely corresponding with the
branches of the artery and frequently unite
before ending in the hypogastric vein.
The SG nerve originates from the sacral
plexus, arising from the fourth and fifth
lumbar and first sacral nerves, and follows
a similar course as the SG blood vessels.
The relationship of the SG artery and
vein to the nerve in the greater sciatic
notch, although recognized, has not been
fully investigated.4,8 These structures may
be injured either from an acetabular or pelvic fracture or during its surgical repair. Iatrogenic injury to the SG vessels and nerve
(SGVAN) can occur during the KocherLangenbeck approach or the posterior approaches to the sacrum, ilium, or sacroiliac
joint.1,8-15 Treatment recommendations for
SG vessel injury (ie, bleeding) from the
notch are based on the close anatomic relationship of these structures to each other.
For example, authors recommend treating
SG artery or vein injury in the greater sciatic notch with packing, which may not be
successful at stopping a hemorrhage.8
In the setting of a hemorrhage, Letournel
and Judet8 stated that the isolation of the SG
nerve from its associated vessels is practically impossible. The rationale for packing
is to avoid inadvertent ligation, clipping, or
cauterization of the SG nerve, which would
be expected to cause permanent abductor
dysfunction, including limping.16 Sequelae
of injuries to these structures, such as hemorrhage, pain, abductor weakness, or gait
disturbances, may potentially be unrec-
e930
ognized iatrogenic injuries. Based on the
close proximity of the SGVAN in the notch
and the potential for iatrogenic injury, it is
helpful for the surgeon to understand the
SGVAN anatomical relationship and potential variations. However, little information is
available describing the actual anatomy and
spatial relationships between the SGVAN at
the greater sciatic notch. The purpose of this
study is to define the anatomical relationships of the SGVAN in the greater sciatic
notch in a human cadaver model.
Materials and Methods
This study was conducted in a bioskills
laboratory adjoining a medical school
gross anatomy laboratory. Twenty-three
hemipelvi were evaluated in 17 embalmed
whole human cadavers using an open posterior approach to the sciatic notch and
the SG neurovascular structures. A single
fellowship-trained orthopedic trauma
surgeon performed the approaches with
the assistance of an orthopedic resident
(C.A.C.). Cadavers were positioned prone
on the operating table. The gluteal musculature was elevated to expose the greater
sciatic notch and posterior ilium. The
SGVAN were identified in the greater sciatic notch and carefully traced deep into the
notch and superficially with elevation of the
gluteal muscles along the posterior ilium.
The piriformis was mobilized medially to
fully assess the structures and assess for
branching. Branching and positional information of the SGVAN were recorded in a
computer database.
Data collected included the gender, age,
and side of the specimens. The SG artery
was evaluated for its proximity to bone and
whether it had major branches present. The
SG vein was characterized by 2 or more
venae comitantes, closely and predictably
associated with the artery and its branches. The SG veins were capacious, thin
walled/brittle, and easily damaged, making quantification of their and the associated relational anatomy difficult to assess.
Thus, for purposes of this study, the veins
were sacrificed in the dissection and the SG
vessels were considered together. The SG
nerve was evaluated for branching, proximity to bone, and anatomical relationship
to the artery.
The demographic and morphologic
data are strictly descriptive not comparative; therefore, descriptive statistics were
used.
Results
Thirteen male and 4 female specimens
were included, with a mean age of 71.2
years (range, 44-94 years). Fourteen right
and 10 left sides were studied. All specimens had a superficial branch dividing off
the main artery (or its branches) upon exiting the notch that travelled peripherally toward the gluteus maximus muscle. At the
notch, the SG arteries comprised a single
vessel in 18 (78%) of 23 specimens, with
all of these dividing at varying distances
(1-3.5 cm) along the lateral ilium after exiting into superior and inferior branches
(Figure 1). In the other 5 (22%) specimens, branching of the artery occurred
deep to or in the notch, resulting in 2 similar sized vessels that exited following a
similar path as the others along the outer
ilium (Figure 2). The SG artery (or its 2
branches) was contiguous with periosteum
of the bony notch in all 23 cadavers.
More than 1 SG nerve branch was
observed at the greater sciatic notch in
all specimens (Figures 1-2). A superior
branch typically exited cranial to the SG
artery and an inferior branch exited caudal
to the artery. The relationship between the
inferior branch of the SG nerve and artery
in the notch was consistent in 21 (91%)
of 23 specimens, with the nerve branch
found in the caudal direction in all cases.
In these cases, the inferior branch of the
SG nerve was found adjacent and caudal
to the artery, lying directly on periosteum
in 14 (67%) specimens and caudal but superficial and nonadjacent to periosteum
in 7 (33%) specimens. In the remaining
2 (9%) specimens, there was more of a
“spray” pattern, where numerous branches of the nerve were present that notably
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n Feature Article
intermingled around the vessels, including lying on periosteum in the caudal to
the vessels. As such, individuals performing surgery along the posterior acetabular
column would expect to encounter the
deep inferior SG nerve branch before the
SG vessels in all cases.
Discussion
The SG artery, vein, and nerve exit the
pelvis through the upper part of the greater
sciatic notch proximal to the piriformis
muscle. The artery divides into several
branches shortly thereafter that travel anteriorly to supply the gluteal musculature or
anastomose with the deep circumflex iliac
and lateral femoral circumflex arteries.4,7
The nerve also branches, coursing along
with the SG blood vessels, innervating the
gluteus medius and minimus, and terminating in the tensor fascia lata.2,3,5
Several prior studies have examined the
SG artery and nerve anatomy on the posterior ilium exiting the greater sciatic notch.
Ebraheim et al4 performed a quantitative
study of the superior gluteal artery in 20
cadavers and noted the following: (1) the
artery exits through the upper part of the
greater sciatic foramen above the piriformis and divides into a superficial branch
(gluteus maximus) and a deep branch
(medius/minimus); (2) the deep superior
branch of the SG artery inserted into the
medius at an average of 29 mm from the
anterior superior iliac spine and provided
4 to 7 perforators to the medius and 0 to 2
perforators to the minimus; and (3) the average distance of the deep inferior branch
of the SG artery from the superior acetabulum was 25 mm and provided 3 to 8 perforators to the medius and 1 to 3 perforators to the minimus. It is this deep inferior
branch of the SG artery that is most at risk
of being injured (ie, excessive retraction,
laceration) during exposure of the posterior column during acetabular surgery (eg,
Kocher-Langenbeck approach).
The authors also noted that, in the majority of cases, the SG nerve was located
just anterior to the SG artery against the
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Figure 1: In the majority of specimens (78%), the superior gluteal (SG) neurovascular anatomy consisted
of a single SG artery lying on the periosteum of the greater sciatic notch with large solitary inferior and
superior SG nerve branch, caudal and cranial to the artery, respectively. Both nerve branches appear at
a high risk for injury during aggressive dissection at or near the notch or during attempts at cauterizing,
ligating, or clipping the SG vessels (A). Alternatively, the artery branched in or deep to the notch (22% of
specimens), sending out 2 arterial branches of the SG artery with a similar branching pattern of the nerve.
A similar SG nerve relationship was seen in these cases as in the single artery specimens (B). In 9% of
specimens, there was a spray pattern of nerve branching where smaller SG nerve branches were present
in the notch, which enveloped the vessels including cranially and caudally, ultimately passing in the directions of the larger nerve branches already described (C).
bony notch. Akita et al2 described the
anatomy of the superior gluteal nerve and
relationship of the SG nerve to the SG
artery external to the notch to their muscular terminations in 10 hemipelvi. Those
authors reported the following: (1) in all
specimens, the SG nerve was divided into
a thick cranial part and a thin caudal part
by the deep branch of the SG artery; (2)
the caudal, or inferior, branch of the SG
nerve ran on the lateral surface of the deep
and upper branches of the SG artery and
supplied the posterior part of the medius;
and (3) branches of the cranial, or superior, branch of the SG nerve formed a bundle that ran along the medial surface of the
deep and lower branches of the SG artery
and supplied the anterior/middle parts of
the medius, the minimus, and the tensor
fascia lata.2
Jacobs and Buxton5 mapped the
course of the SG nerve on the lateral
ilium and found that in 18 of 20 specimens, the SG nerve divided within 1 or
2 cm from the superior border of the piriformis. These SG branches then “fanned”
out along the intramuscular plane between the gluteus medius and minimus
muscles.
Despite numerous studies regarding
the SGVAN anatomy deep and periph-
Figure 2: Clinical photograph from a cadaver
dissection showing the relationship of the superior gluteal (SG) artery and its branches exiting
the greater sciatic notch, with associated inferior
branch of superior gluteal (IBr SG) nerve exiting
the notch caudally.
eral to the greater sciatic notch, to the
authors’ knowledge, this study is the first
that has evaluated the positional anatomy
of the SGVAN at the notch, which might
be valuable information for an acetabular
or hip surgeon who encounters intraoperative bleeding from the greater sciatic
notch. Furthermore, despite seemingly
concise descriptions in some of these previous studies, the current authors encountered some variation of the SG anatomy
in this area. The following anatomy was
observed:
1. The SG artery lay on the periosteum
of the posterior ilium at the notch, exit-
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ing as 1 vessel (78%; Figure 1A) or divided in the notch into 2 similarly sized
branches (22%; Figures 1B-C). Either
way, upon exiting the notch, a superficial
branch split off toward the medial gluteus maximus. Then, the deep SG artery
coursed superiorly and anteriorly along
the ilium between the gluteus medius and
gluteus minimus. If the deep branch was 1
vessel exiting the notch, it quickly bifurcated into superior and inferior divisions
that separated coursing anteriorly along
the outer ilium.
2. Anatomy of the SG veins included
more than 1 branch, intimately associated with the artery as is typical for venae
comitantes. The positional relationships
of the nerve and nerve branches to the
vein were similar to that for the artery
and nerve.
3. The SG nerve may exit the notch
in 2 (superior and inferior) or more
branches (Figure 1). These branches
of the SG nerve then course along the
outer ilium with the superior and inferior
branches of the SG artery. The deep inferior branch(es) of the SG nerve appear to
be at greatest risk during exposure of the
posterior column or in attempts to stop
bleeding from an injured artery.
Conclusion
Several scenarios exist in which specific knowledge of the SGVAN anatomy
would be particularly important to a pelvis and acetabular surgeon.8 Posterior
column fractures often exist in this area,
creating sharp edges that may injure or
predispose the SG anatomy to iatrogenic
injury. The Kocher-Langenbeck approach
to the posterior column itself risks injury
to the superior gluteal vessels and nerves
that are tethered through the greater sciatic notch. The SGVAN lie on the deep,
or medial, surface of the gluteal muscles.
During elevation of the glutei near the
notch in acetabular surgery (or during retractor placement in the notch in posterior
approach to sacrum), the vessels may be
torn or stretched, typically where they lie
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against the ilium at the top of the notch.
If transected, they may retract into the
pelvis with subsequent intrapelvic hemorrhage, or more simply may be partially
lacerated and continue to bleed because
direct visualization is usually difficult in
this area.
If injury occurs, placing a laparotomy sponge or a procoagulant substance
in the notch is advised—as opposed to
cauterization or application of a ligature
or vascular clip, which would place the
SG nerve or its major branches at risk.
In infrequent cases, angiography or the
use of an anterior surgical approach have
been necessary to control hemodynamic/
physiologic instability despite these recommendations.
Although not in the scope of this article, some acetabular surgeons will perform a trochanteric slide osteotomy to facilitate mobilization of the abductors and
prevent the aforementioned iatrogenic injury to the SGVAN.17
The SGVAN supply vascularity and
innervation to the gluteus medius, gluteus
minimus, and tensor fascia lata and are at
risk in patients with a pelvic or acetabular
fracture and those undergoing pelvic or
acetabular surgery. During the KocherLangenbeck approach, the deep inferior
branches of the SGVAN are at risk. The
nerve is encountered first because the
SG nerve is always caudal to the vessels.
Although the anatomy of the individual
structures (ie, nerve or artery) has been
individually described and injuries to
these neurovascular structures are documented, prior to the current study little
attention had been paid to defining their
anatomical relationships to dictate surgical treatment if the surgeon experiences
uncontrolled bleeding from the greater
sciatic notch. Iatrogenic injuries such as
these should be averted if the surgeon is
cognizant of the anatomic relationship of
these structures to each other and uses appropriate practice (ie, packing or a procoagulant) if unforeseen hemorrhage is
encountered.
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