Download A Minimally Invasive Approach for Plate Fixation of the Proximal

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Bulletin • Hospital for Joint Diseases
Volume 62, Numbers 1 & 2
2004
A Minimally Invasive Approach for Plate Fixation
of the Proximal Humerus
Michael J. Gardner, M.D., Matthew H. Griffith, M.D., Joshua S. Dines, M.D., and
Dean G. Lorich, M.D.
Abstract
Plate fixation for unstable fractures of the proximal humerus has seen mixed results as evidenced by the trials
of new methods of fixation. The deltopectoral surgical
approach is most frequently used and requires significant
muscle retraction and soft tissue stripping to expose the
lateral humeral neck. This may contribute to avascular
necrosis and fixation failure. Lateral approaches have
been limited to 5 cm distal to the acromion because of
the course of the anterior branch of the axillary nerve.
A recent anatomic study has demonstrated the predictability of the position of the axillary nerve as it crosses
the anterior deltoid raphe, which allows it to be isolated
and protected, and dissection can be extended distally.
In addition, no accessory motor branches to the anterior
head of the deltoid cross the raphe, so extending an incision through the raphe after protecting the main motor
branch of the axillary does not place the innervation to
the anterior deltoid at risk. This surgical approach allows
exposure of the proximal humerus and indirect reduction
of the fracture, with subsequent locking plate fixation,
adhering to the principles of biological fixation.
W
ith the advent of locking plates for fixation
of proximal humerus fractures, modification
of previously described surgical approaches
is essential. The traditional deltopectoral approach for
the anterior and lateral shoulder region requires extensive soft tissue dissection and muscle retraction to gain
adequate exposure to the lateral aspect of the humerus
Michael J. Gardner, M.D., Matthew H. Griffith, M.D., Joshua S.
Dines, M.D., and Dean G. Lorich, M.D., are in the Department
of Orthopaedic Surgery, Hospital for Special Surgery, New York,
New York.
Correspondence: Michael J. Gardner, M.D., Hospital for Special
Surgery, 535 East 70th Street, New York, New York 10021.
for application of a plate. Poor results following plate
fixation of proximal humerus fractures may be related to
complete exposure of the fracture fragments and devascularization during dissection and plating, or disruption
of the critical blood supply to the humeral head. In light
of the recent trend toward “biological fixation,” which
focuses on fixed-angle screws, percutaneous bridge plating techniques, and avoidance of both fracture exposure
and anatomic reduction,1 new surgical techniques must
be developed for proper application of these devices.
For access to rotator cuff tears using a mini-open
approach, a small raphe-splitting incision from the
acromion several centimeters distally has been well described.2-5 However, distal extension through the raphe
of more than 3 or 4 centimeters has been discouraged
because of the risk of damaging the axillary nerve. Recently, an anatomic study was performed to characterize
the axillary nerve as it crosses the raphe between the
middle and anterior heads of the deltoid.6 The anterior
motor branch of the axillary nerve was found to cross the
surgical neck at a predictable location relative to both the
acromion and the greater tuberosity, and at the level of
the raphe no other motor branches crossed to innervate
the anterior head of the deltoid (Fig. 1). This data may
be useful in allowing a more direct surgical approach to
the proximal humerus for plate fixation of fractures.
Surgical Technique
A skin incision was made beginning at the anterolateral
tip of the acromion. It was extended approximately 5
cm distally through the subcutaneous tissue layer to the
level of the deltoid muscle (Fig. 2A). The avascular raphe
separating the anterior and middle heads of the deltoid
was then identified as a white band of connective tissue
between the two muscular heads. Immediately adjacent
to the raphe’s attachment to the acromion, it was incised
Bulletin • Hospital for Joint Diseases
Volume 62, Numbers 1 & 2
2004
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B
A
Figure 1 Examples of exposure of the axillary nerve and posterior humeral circumflex vessels as they traverse the anterior deltoid raphe
of a right cadaver shoulder. No other branches cross the raphe to innervate the anterior head of the deltoid.
sharply for 2 cm along its length distally, enough to allow the insertion of the surgeon’s finger. The surgeon’s
finger was then inserted into the rent in the raphe swept
posteriorly to palpate undersurface of the deltoid and
raphe. The axillary nerve was readily palpable as a
cord-like structure between the deltoid and humerus as it
exits the quadrangular space with the posterior humeral
circumflex vessels.
Once a general idea of the nerve’s location was obtained,
the incision in the raphe was carefully extended distally by
sharp dissection. Deep to the raphe, approximately 6.5 cm
distal to the inferior edge of the acromion and 3.5 cm from
the lateral prominence of the greater tuberosity, the axillary nerve and posterior humeral circumflex vessels were
identified, isolated, and protected with a vessel loop (Fig.
A
2B). With the neurovascular bundle protected, the incision
may be extended distally to the deltoid tuberosity. The
fracture may be indirectly reduced using ligamentotaxis
and Kirschner wires in the head and shaft as joysticks. A
fixed-angle plate can then be inserted along the lateral neck
and shaft from proximal to distal underneath the nerve and
vessels without excessive tension (Fig. 3).
Discussion
Operative fixation of proximal humeral fractures is indicated in approximately 20% of cases, the majority of
which are three- and four-part fractures according to the
Neer classification. 7 Treatment options vary from closed
reduction with percutaneous pinning to hemiarthroplasty
and the appropriate method depends on the fracture pat-
B
Figure 2 Illustration of the extended anterior acromial approach. The incision begins from the anterolateral corner of the acromion
and extends distally. Deep to the subcutaneous layer, the anterior deltoid raphe, separating the anterior and middle heads of the deltoid,
is identified (A). After palpating the undersurface of the deltoid to palpate the neurovascular bundle, the raphe is split and the nerve is
isolated and protected (B).
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Bulletin • Hospital for Joint Diseases
Volume 62, Numbers 1 & 2
Figure 3 Demonstration in a cadaver shoulder of isolating the
axillary nerve and posterior humeral circumflex vessels, followed
by advancing a plate from proximal to distal deep to the neurovascular bundle.
tern, surgeon’s experience, and specific patient factors
such as age and bone quality. Key principles for obtaining
a satisfactory result include stable fixation to allow early
mobilization and minimization of soft tissue disruption
to prevent further vascular compromise. Complications
such as rotator cuff dysfunction, stiffness, avascular necrosis, malunion, and nonunion are relatively common
with proximal humerus fractures and can be a significant
source of morbidity.
The anterior and middle heads of the deltoid are separated by an avascular fibrous raphe.8,9 The course of the
axillary nerve after it exits the quadrilateral space has
been well described,10-16 but its position in relation to
the raphe has only recently been reported.6 The anterior
motor branch of the axillary nerve crosses the humerus
transversely at variable distances as a single nerve and
penetrates the fascia of the deltoid before or after dividing
into several smaller branches.8,12 Duparc and colleagues11
found that in 12 of 32 shoulders (38%), the anterior
trunk branched into smaller motor branches after entry
into the anterior head of the deltoid, and in the remaining specimens the division occurred at variable distance
prior to muscle entry. These investigators did not focus
on the raphe specifically.
Innervation of the deltoid is from the axillary nerve,
which arises from the posterior cord of the brachial plexus and passes through the quadrilateral space dividing
into anterior and posterior branches. The posterior branch
sends several smaller branches to the teres minor, the
deltoid, and the superior lateral brachial cutaneous nerve.
The anterior motor branch courses around the neck of the
humerus and passes medially on the anterior surface of
the surgical neck to supply the middle and anterior deltoid
heads. The locations of the intramuscular branches are
variable and when the deltoid is split intramuscularly
2004
for more than several centimeters distally, denervation
of the anterior head of the deltoid from disruption of
these fibers invariably occurs. Division of the raphe
distally may avoid these problems. It has been shown
that several branches to the middle head from the main
branch occur approximately 9.8 mm before crossing the
raphe, the main anterior motor branch crosses the raphe
as a single nerve, and the first branches from the main
trunk to the anterior head arise approximately 8.5 mm
after crossing the raphe.6 Thus, as the raphe is divided,
as long as the main anterior motor trunk is protected, no
other branches are at risk.
The deltopectoral approach for exposure of the anterior and lateral shoulder region has been most commonly
used for plating of the proximal humerus. However, accessing the lateral aspect of the proximal humerus using
this approach requires extensive soft tissue dissection
and retraction, as it is an indirect approach to the plating zone. This is less than ideal for internal fixation of
proximal humerus fractures and it further jeopardizes the
compromised blood supply to the head of the humerus
and fracture fragments. It has been advised that any dissection lateral to the deltoid-pectoral interval in the distal
direction be limited to three to five centimeters from the
acromion to avoid injury to the axillary nerve.8,9,12,17,18
Recent data has shown that the anterior motor branch
of the axillary nerve crosses the raphe at a predictable
location relative to the acromion and greater tuberosity,6
which allows more direct access to the proximal humerus
after protecting the axillary nerve.
The incidence of avascular necrosis after closed reduction ranges from 3% to 14% in three-part fractures
and up to 34% in four-part fractures.19 Surgical insult of
the soft tissue envelope and direct manipulation of the
fracture fragments with disruption of the consolidating
callous further increase this risk and avascular necrosis
may be as high as 37% following open reduction and
internal fixation.20 The head of the humerus is perfused
by branches of the anterior humeral circumflex, posterior
humeral circumflex, suprascapular, thoracoacromial, and
subscapular arteries. The anterior and posterior humeral
circumflex vessels have branches that directly penetrate
bone; other arteries contribute through anastamosis systems with the circumflex vessels. Gerber and associates21
reported that the anterior humeral circumflex artery was
the only artery that could alone supply the entire humeral
head and that the posterior humeral circumflex artery
mainly supplied the greater tuberosity and a small area of
the humeral head through interosseous anastamoses with
branches of the anterior circumflex artery. The anterior
circumflex humeral artery arises from the axillary artery
about one centimeter distal to the inferior border of the
pectoralis major and courses laterally along the inferior
border of the subscapularis tendon. Its course places it
at risk when a standard deltopectoral approach is used,
Bulletin • Hospital for Joint Diseases
A
C
Volume 62, Numbers 1 & 2
2004
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B
D
Figure 4 A 64-year-old female with osteoporosis fell on her left side and sustained a comminuted proximal humeral fracture (A and
B). An extended anterior acromial approach was used; the axillary nerve and vessels were isolated and length, alignment and rotation of
the fracture were obtained. A locking plate was then applied (C), to which the tuberosities were sutured anatomically. A postoperative
radiograph shows anatomic reduction (D).
particularly with distorted anatomy in the setting of a
fracture. The posterior humeral circumflex artery passes
through the quadrilateral space with the axillary nerve.
Both of these structures are readily visualized and protected using the anterolateral raphe-splitting approach,
and there is no dissection medially near the course of the
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Bulletin • Hospital for Joint Diseases
Volume 62, Numbers 1 & 2
critical anterior humeral circumflex artery.
The recent rise in popularity of using fixed-angle
plate-screw constructs to provide biologic fixation has
altered many surgeons’ approach to fracture management.1,22 These plating systems act as internal fixators and
have the advantage of not requiring periosteal stripping
or direct apposition of the plate onto bone. The focus is
shifted from absolute mechanical rigidity to biological
preservation.23,24 The plate can be inserted through a small
incision remote to the fracture site, preserving the soft
tissues and precluding the need for direct exposure of the
fracture fragments. Because there is only point contact
with bone and no friction is required between the plate
and bone, these devices act as pure splints. No longer is
a tight interface between the plate and bone required for
stability, rather load is distributed evenly among all the
bone-screw interfaces.25 Reduction of temporary cortical
porosis by vascular preservation and improved mechanical stability without fragment compression are two of the
key benefits of locked plating. This concept of flexible
fixation has been shown to promote callus formation,1,26,27
and animal studies have revealed stronger bone after
hardware removal as well as decreased complications,
such as infection and stress shielding.27
As internal fixation concepts and techniques continue
to evolve, the development of novel minimally-invasive
surgical approaches is critical. The degree of soft tissue
dissection inherent in the deltopectoral approach is counterproductive when attempting to adhere to the principles
of biological fixation. This extended anterior acromial
approach allows a limited surgical approach to be used,
preserving the periosteum, and when coupled with locked
plating, provides stable fixation to initiate indirect bone
healing.28 These techniques may be particularly useful
in osteoporotic proximal humerus fractures, where screw
purchase may be suboptimal, and in unstable surgical
neck fractures, which are inherently unstable (Fig. 4).
Though further clinical study is warranted, use of this
approach may decrease complications and improve outcomes in the operative treatment of proximal humerus
fractures.
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