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Current Concepts
The Snapping Scapula: Diagnosis and Treatment
LT Michael Kuhne, M.D., M.C., U.S.N., Nicole Boniquit, B.A., Neil Ghodadra, M.D.,
Anthony A. Romeo, M.D., and CDR Matthew T. Provencher, M.D., M.C., U.S.N.
Abstract: As a largely under-recognized problem, snapping scapula stems from the disruption of normal
mechanics in scapulothoracic articulation. It is especially common in the young, active patient population,
and symptoms are frequently seen with overhead and throwing motions. Understanding the anatomy of
the scapula and surrounding neurovascular structures is crucial in making a differential diagnosis and
providing both nonoperative and surgical treatments. Common causes of snapping scapula include
bursitis, muscle abnormality, and bony or soft-tissue abnormalities. Anatomic variations, such as excessive forward curvature of the superomedial border of the scapula, may also be a cause for snapping.
Benign tumor conditions of the scapula can also predispose one to snapping scapula syndrome and should
be thoroughly investigated during the course of treatment. Patients with snapping scapula syndrome
typically present with a history of pain with overhead activities. Snapping scapula is associated with
audible and palpable crepitus near the superomedial border of the scapula. Various imaging studies may
be used to rule out soft-tissue and bony masses, which may cause impingement at the scapulothoracic
articulation. In most cases nonoperative treatment is curative and includes physical therapy for scapular
muscle strengthening and nonsteroidal anti-inflammatory medications. Corticosteroid injections may also
be used for therapeutic and diagnostic purposes. In most cases overuse injuries and repetitive strains
respond well to nonoperative treatments. When nonoperative measures fail, surgery is a proven modality,
especially if a soft-tissue or bony mass is implicated. Both open and arthroscopic techniques have been
described with predictable results. Key Words: Snapping scapula—Bony abnormality—Scapula—
Superomedial bursitis—Bursitis.
S
napping scapula is a largely under-recognized
problem. Patients present with palpable, audible,
and painful crepitus of the scapula causing diminished
From the Department of Orthopaedic Surgery, Naval Medical
Center San Diego (M.K., M.T.P.), San Diego, California, and
Department of Orthopaedic Surgery, Rush University Medical
Center (N.B., N.G., A.A.R.), Chicago, Illinois, U.S.A.
Dr. Romeo is supported by funding from Arthrex, Naples, FL.
The views expressed in this article are those of the authors and
do not reflect the official policy or position of the Department of the
Navy, Department of Defense, or US Government.
Address correspondence and reprint requests to CDR Matthew T.
Provencher, M.D., M.C., U.S.N., Department of Orthopaedic Surgery,
Naval Medical Center San Diego, 34800, Bob Wilson Dr, Suite 112 San
Diego, CA 92134-1112, U.S.A. E-mail: mattprovencher@earthlink.
net
© 2009 by the Arthroscopy Association of North America
0749-8063/09/2511-8639$36.00/0
doi:10.1016/j.arthro.2008.12.022
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quality of life. Snapping scapula is most often caused
by repetitive shoulder girdle stress and overhead arm
use, although the differential diagnosis is quite extensive.1 The patient population is, therefore, normally a
younger, active population. Although less common
than other disorders of the shoulder, this disorder is a
source of chronic pain and limited function for affected patients that oftentimes can be overlooked in
the evaluation of those with upper extremity complaints.2 Although most of the patients are treated
successfully with nonoperative measures, surgical intervention is a proven modality.
ANATOMY
An understanding of the anatomy and physiology of
the scapulothoracic articulation is required to understand the pathogenesis of scapulothoracic disorders.
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 25, No 11 (November), 2009: pp 1298-1311
SNAPPING SCAPULA
The scapula is a triangular-shaped bone articulating
with the posterior thorax. It is attached to the axial
skeleton by only the acromioclavicular joint, and
therefore its stability is dependent on surrounding
musculature.3
The periscapular musculature creates stability of the
scapulothoracic articulation. The levator scapulae and
rhomboids attach to the medial border of the scapula,
whereas the subscapularis is on its anterior surface.1,4
The serratus anterior originates on the ribs and inserts
on the medial scapular anterior surface. A cushion
between the scapula and the thoracic wall is created by
the serratus anterior and the subscapularis.5-8 Two
spaces, the subscapularis space and the serratus anterior space, are created by the musculature of the joint.
The serratus anterior space is located between the
chest wall, serratus anterior, and rhomboids. The subscapularis space is bounded by the serratus anterior,
subscapularis, and axilla.6,7,9,10 Three muscles of the
rotator cuff originate at the scapula: the supraspinatus
and the infraspinatus on the posterior surface of the
scapula and the subscapularis on the anterior surface
(Fig 1).
There are several important neurovascular structures surrounding the scapula. The accessory nerve
goes through the levator scapulae muscle near the
superomedial angle of the scapula and runs along the
medial scapular border deep to the trapezius muscle.
The transverse cervical artery branches into the dorsal
scapular artery (deep branch) and a superficial branch
that travels with the accessory nerve. The dorsal scap-
FIGURE 1. Superior view of cross-sectional anatomy showing the
subscapularis and serratus anterior spaces, created by surrounding
subscapularis and serratus anterior musculature. Their relation to
the thoracic rib cage and overlying scapula should be noted. These
spaces are important to distinguish because they may be sources of
subscapular pain and “snapping.”
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FIGURE 2. Posterior view of scapular anatomy showing the relative location of key muscle attachments and nerve structures. The
deep scapular musculature is reflected to delineate the attachment
points of the muscles to the scapula. (n, nerve; a, artery.)
ular artery travels with the dorsal scapular nerve 1 cm
medial to the medial border of the scapula. They
pierce the scalenus medius and travel deep to the
rhomboid major and minor. The nerve innervates both
of these structures. The long thoracic nerve is located
on the surface of the serratus anterior. The suprascapular nerve and artery pass toward the suprascapular
notch on the superior scapular border medial to the
base of the coracoid (Fig 2).6,7,9,11
Several scapular bursae have been implicated in the
development of scapular bursitis, which can lead to
pain and snapping. Bursae are located in areas of
friction and are potential spaces lined by a synovial
membrane.1 Two major bursae are found consistently
in patients: the infraserratus bursa located between the
serratus anterior and the chest wall and the supraserratus bursa located between the subscapularis and
serratus anterior.3,4,6,12-15 These can be noted on both
dissection and arthroscopy (Fig 3).4
There are 4 minor bursa that are found inconsistently and are usually present as a response to abnormal scapulothoracic articulation mechanics. These minor bursae are located at the superomedial angle of the
scapula and can be either inferior or superior to the
serratus muscle. Another infraserratus bursa can be located at the inferior angle of the scapula, and the trapezoid bursa is located at the medial base of the spine under
the trapezius.3,4,7,12-15 The bursa at the superomedial angle is the most common source of symptoms, with the
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FIGURE 3. Location of scapular bursal spaces in posterior
(A) and superior (B) cross-sectional views.
inferior angle as the second most common site for scapular bursitis.4,12,15
Pearls
●
The dorsal scapular artery and nerve run along the
medial border of the scapula.
● The suprascapular nerve passes through the scapular notch, and the suprascapular artery passes
over the superior transverse scapular ligament.
● The 2 main bursa that become inflamed are the
infraserratus and supraserratus.
● The main neurovascular structures near the scapula are the transverse cervical artery, dorsal scapular artery, suprascapular artery, dorsal scapular
nerve, long thoracic nerve, suprascapular nerve,
and accessory nerve.
PATHOPHYSIOLOGY
Snapping scapula occurs when the normal smooth
gliding of the concave portion of the anterior scapula
over the convex thorax is disrupted.6,9,16,17 The motion
of the shoulder is a combined motion of both the
scapula and the humerus to maximize joint stability
and function by minimizing the load on the glenohumeral joint and the acromioclavicular joint.18-20
The scapula moves with motion of the arm to ensure
proper positioning of the glenohumeral joint. The purpose of this positioning is to stabilize, absorb, and
transfer forces that are generated by the articulating
humerus. The glenohumeral joint must remain stable
throughout its full range of motion for the rotator cuff
muscles to adequately maintain joint integrity. Snap-
ping scapula occurs predominantly with overhead and
throwing motions. During the cocking phase of throwing, the scapula externally rotates (retraction). Then,
in the acceleration phase, the scapula will internally
rotate (protraction) and move anteriorly around the
thoracic cage as the arm moves forward in followthrough. Superior elevation of the scapula also occurs
during the cocking and acceleration phases. Scapular
protraction, retraction, and superior elevation occur
through action of the serratus anterior, trapezius, and
rhomboid muscles to avoid impingement of the rotator
cuff.21,22
The etiology of snapping scapula is divided into 3
major categories: bursitis, muscle abnormality, and
bony or soft-tissue abnormality.5,6,12,17,23,24 Regardless of the etiology, the snapping occurs because of
abnormal mechanics of the scapula grating on the
underlying ribcage during arm movement with sound
amplified by the thoracic cavity.1,4,5 Bursitis originates
from a soft-tissue disorder, whereas crepitus is commonly from an osseous abnormality with grating or
thumping of the scapula against the ribcage.4
The etiology of scapular bursitis is an overuse injury causing reactive bursa formation in a cycle of
inflammation, reactive bursitis, and scarring. Repetitive motion of the scapula over the thorax irritates soft
tissues and forms muscular microtears, causing
chronic bursitis and inflammation. Resolution of the
inflammation occurs in the form of scar tissue. Scarred
periscapular musculature or bursa leads to impingement, pain, and further inflammation. The result is
fibrosis of the bursa with secondary scarring, pain, and
snapping.1,4,12
SNAPPING SCAPULA
Another common cause of scapular snapping is
muscular abnormality.25 The scapular stabilizer muscles function in an endurance capacity to position the
glenohumeral fossa in the appropriate position for
overhead activities. Atrophied muscle, fibrotic muscle, or anomalous muscle insertions, most commonly
of the serratus anterior muscle, cause abnormal scapular movement, leading to snapping. Rhomboid and
levator scapulae weakness, muscle trauma, or complications from shoulder surgery may be other causal
factors.5,14,15,26 Arm elevation induces a posterior tilting of the scapula, thus compressing the space between the inferior pole and the ribcage.3 Tightness in
the pectoralis minor, which attaches to the coracoid
process, can pull forward on the scapula, causing an
anterior tilt, decreasing the space between the superior
scapula and the thoracic wall.21 Anatomically, there is
less muscle mass on the medial border of the scapula
where the subscapularis is thinnest, predisposing this
location to rub against the ribcage.5-7,9,17,26
Bony and soft-tissue lesions, including scapular anatomic variation, osteochondroma, chondrosarcoma,
or elastofibroma dorsi, comprise a less common group
of causal factors. Anatomic variations are the most
common subgroup and are caused by a hooked superomedial angle, Luschka’s tubercle, reactive spurs,
or malunited rib fractures.1,3-5,7,9,14-17,24,25,27 Luschka’s
tubercle is a prominence of bone or fibrocartilage at the
superomedial angle of the scapula. Bone spurs occur
from repetitive periscapular muscle avulsions.4,7,8,15 The
most frequent deformity of the superomedial border is a
bulbous top or anterior hook/angle rubbing across the
ribs.28 The superomedial border and the inferior pole of
the scapula have wide anatomic variability.27 When no
obvious deformity is found, it is hypothesized that an
excessive forward curvature of the superomedial corner
of the scapula is the cause of the disorder.7-9 A bony
projection at the inferior pole is present in 22% of the
population, making it the second most common site for
symptoms.27 Although the previously mentioned scapular anatomic variants increase the risk of snapping scapula, many persons with anatomic variations are asymptomatic. Conversely, other cases of snapping scapula
have no visible anatomic cause.29 Any abnormal bone
formation can cause a hot spot, leading to snapping, pain,
and reactive soft-tissue changes.3,4,15,23,26
Osteochondroma of a rib or the anterior surface of
the scapula is usually diagnosed in adolescence and
early adulthood. Although it is the most common bony
anomaly causing this disorder, it is a rare benign
tumor. When present on the anterior scapular surface,
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it will invade into the scapulothoracic space, disrupting smooth motion.5,7,8,15,17,24,29-31
Scapular chondrosarcomas are infrequently the
cause of snapping scapula. They are slightly more
predominant in male patients and occur most frequently between 40 and 70 years of age. Surgical
excision with wide margins is needed for curative
treatment but is difficult because of the extensive
neurovasculature around the scapula.32
Another infrequent cause of snapping scapula,
elastofibroma dorsi, is a slow-growing, benign softtissue tumor. Seen more commonly in elderly women,
it is located in the subscapular or infrascapular region
on the chest wall at the level of the rhomboid major
and latissimus dorsi muscles.33,34 It can also occur in
athletes and is believed to form in response to repetitive microtrauma.3 Although it is firmly adherent to
the costal wall, this connective tissue lesion elevates
the inferior scapula.13,35
Pearls
●
Bursitis is a reaction due to overuse or repetitive
trauma of the articulation.
● Muscle weakness or changes can disrupt the articulation, causing crepitus or bursitis.
● Bony abnormalities include an angulated superomedial scapular angle, rib fractures, osteochondroma, Luschka’s tubercle, or reactive spurs.
PATIENT PRESENTATION
The patient will most commonly present to the physician with a history of pain during overhead activities,
repetitive overuse of the shoulder, or even a single traumatic injury.3,4,9,11,12,14,15,36,37 Patients describe an audible and palpable crepitus with active shoulder movements, including shrugging of shoulders.9,38,39 There
may be continuous grating of muscles, coarse thumping, a single snap, or intermittent clunks.25 Other
descriptive terminology includes clicking, crunching,
grating, or snapping sensations.1,11,40 These symptoms
may result from participation in sports activities, including swimming and throwing, or from other rapid
overhead arm movements.1,3,12,15,41 Pain may be severe enough to limit activities. Most often the location
of the pain is at the superomedial angle or inferior pole
of the scapula with variable amounts of cervical radiation.9,14,27 Symptoms will range from annoying to
painful to disabling.4
On examination, the physician can feel crepitus,
elicit tenderness to palpation, and hear the snapping in
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most patients. The patient most commonly will have
tenderness to palpation at the superomedial border or
inferior pole of the scapula.3,12 The patient can also
present with tenderness to palpation located over the
levator scapulae, trapezius, and/or rhomboid muscles.
The patient will almost always have palpable crepitus
with or without audible snapping.1,3,5,9 The crepitus is
easily reproduced during arm movement because pain
occurs most commonly with shoulder abduction. The
crepitus may be accentuated when the superior angle
of the scapula is being compressed against the chest
wall during arm abduction.42 Pain is normally not
reproducible with isometric movements.1,27,38,39 The
pain and snapping may be decreased when the patient
puts the hand of the affected shoulder on the opposite
shoulder, thus lifting the scapula from the ribcage.5
It is important to assess scapular symmetry. The
presence of winging or fullness may be the result of an
underlying mass or space-occupying lesion. A mass
does not always present with pseudo-winging of the
scapula.4,43 The patient’s posture should also be assessed to rule out kyphosis.3 Palpable crepitus may
have a familial tendency and can be bilateral in some
patients.4,39
Scapular bursitis presents with fullness over the
bursa.4 Pseudo-winging may be present as the patient
compensates for pain.12,14 Palpation of the scapula
during arm range of motion can pinpoint the location
of bursitis.4 If the scapulothoracic bursa is inflamed,
the pain will be deep to the levator scapulae and the
superomedial angle of the scapula. Pain at the trapezoid bursa is rarer and more superficial, with pain over
the junction of the spine and the medial border.14
Radiographic evaluation of the snapping scapula is
important to rule out osseous deformity, tumors, or
other bony causes of the patient’s pain. Plain radiographs should be the first study in the evaluation of the
patient with scapular snapping. A lateral scapular
view (also called the tangential or oblique view) in
TABLE 1.
Bony Pathology/Soft-Tissue Mass
Osteochondroma
Luschka’s tubercle
Reactive bone spur
Abnormal scapular superior angle curvature
Rib fracture
Elastofibroma
Chondrosarcoma
addition to anteroposterior and axillary views is obtained in the plane of the scapula.3-5,8,9,12,14,26,38 In
patients with normal radiographs but suspected osseous lesions or fractures, a computed tomography (CT)
or magnetic resonance imaging (MRI) scan should be
obtained.12 A low threshold is necessary for obtaining
MRI or CT scans because the anterior scapula is
difficult to visualize with conventional radiographs.
The usefulness of 3-dimensional CT scans versus
conventional CT scans has been evaluated. Threedimensional CT can show the exact location of the
snapping site and show superomedial scapular angulation, and it can be used to distinguish soft-tissue
from bony incongruity and note the size of a deformity. This information is useful for noting the exact
location for injection or surgical intervention. This
modality is best used when conservative treatment
fails and surgical intervention is a possibility.23,44 It is
more sensitive than plain radiographs and regular CT
scans.24,26 MRI is useful in the diagnosis of bursitis
and soft-tissue masses, such as elastofibroma dorsi.
Bursae on MRI show a well-demarcated cystic mass
with high T1 and T2 signal intensity and are normally
located between the serratus anterior and the lateral
chest wall.4,13,33,45 The differential diagnosis includes
several diagnoses that implicate the shoulder girdle
(Table 1).
Pearls
●
Scapular motion causes noise or palpable crepitus.
● Pain is most common at the superomedial or
inferior pole of scapula, especially with overhead
activities.
● Radiographs or CT scans are usually normal.
Three-dimensional CT reconstruction may show
the snapping site.
Differential Diagnosis
Soft-Tissue Pathology
Postural Causes
Shoulder Girdle
Bursitis
Muscular weakness, atrophy, anatomic
variation
Scoliosis
Kyphosis
Glenohumeral pathology
Periscapular muscle strain
Winged scapula
Neurogenic disorder
SNAPPING SCAPULA
INDICATIONS FOR NONOPERATIVE
VERSUS OPERATIVE TREATMENT
Despite the underlying cause of the diagnosis, a trial
of nonoperative treatment is warranted. Given the
high success rate of nonoperative interventions, they
should be trialed for at least 6 months to 1 year before
surgical intervention is considered.3
Snapping scapula responds to nonoperative treatment when caused by overuse and repetitive strain.12
However, if it is caused by an anatomic lesion that it
is unlikely to benefit from nonoperative measures, a
trial of nonoperative care is still warranted.4,12 When
there is evidence of an anatomic or bony abnormality,
excision has a high success of achieving permanent
cure.4,5,15,17,23-25,33,40
Scapular crepitus can occur in approximately 30%
of normal asymptomatic persons.3,4,15,17 Painless crepitus is more common than painful crepitus and does
not usually need to be treated.36 However, a painful,
clinically significant snapping may occur without
sound or crepitus, and treatment is indicated, starting
with nonoperative measures.14
Indications for surgery include failure of nonoperative measures. Surgery has an increased success
rate if the patient responds to corticosteroid injections.4 Removal of the superomedial corner of the
scapula even in patients in whom no bony abnormality
is noted has been shown to be effective.9,16 The surgical candidate should be motivated, compliant, and
have pain that significantly interferes with his or her
quality of life.14 Contraindications to surgery include
neck problems, other shoulder problems, neurologic
deficits in the arms, or wasting of periscapular musculature.10
Both open and arthroscopic techniques have been
described in the literature. The open surgical technique has an excellent track record, but concerns regarding the morbidity of the approach and cosmesis
are important to discuss with the patient. The arthroscopic technique is more technically demanding, and
the lack of bony landmarks can increase the risk of
damage to neurovascular structures.36
Pearls
●
A trial of nonoperative treatment is the mainstay
of treatment.
● Bony anomalies or radiographic abnormalities
respond well to surgical intervention with removal of the lesion.
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NONOPERATIVE TREATMENT
Nonoperative management must focus on the scapular muscles and possible postural causes of abnormal
scapulothoracic articulation.3,46 Because the major etiologic factors are overuse or improper joint mechanics, the patient must first modify activities and rest the
joint to calm the cycle of bursitis and scarring. A
course of nonsteroidal anti-inflammatory medications
helps decrease inflammation.4,12 A trial of physiotherapy can be initiated to realign joint mechanics. If the
patient is unable to undergo physical therapy and is
continuing to have pain, then an injection of anesthetics and steroids is warranted.4,12,36,40
Ice, heat, and ultrasound treatments have been described with variable success.1,4 Muscular training and
postural training are the most beneficial treatments.
Postural training to minimize kyphosis, promote upright posture, and strengthen upper thoracic musculature is indicated for cases in which posture is the
proposed causal factor. A figure-of-8 harness may
assist in postural training.4,12,14,15,26,47 Because the
scapula is responsible for static stability of the
shoulder girdle, endurance training is the key for
scapular stability. This type of training necessitates
low-intensity, high-repetition exercises. Strengthening of the subscapularis and serratus anterior
helps achieve successful results because a weak
serratus anterior muscle may allow the scapula to tilt
forward, causing crepitus.3,12,14,48,49 Scapular adduction and postural shoulder shrug exercises are of the
utmost importance because they strengthen the scapular stabilizers, including the serratus anterior, rhomboids, and levator scapulae (Fig 4).7,16,17 Abduction
and elevation of the scapula cause increased pressure
and strain on the underlying musculature and should
be avoided.3
If nonsteroidal anti-inflammatory drugs and physical therapy are unable to control the pain, scapular
injection is a useful tool.15,17 The injection is given
with a 1.5-inch 22- to 25-gauge needle. The patient
lies prone with the arm in a chicken-wing position
with the hand behind the back. This places the shoulder in a position of extension, internal rotation, and
adduction. After a sterile environment is obtained, the
needle is inserted parallel to the anterior border of the
scapula, with care taken not to penetrate too deeply
causing a pneumothorax. For pain at the inferior angle
of the scapula, the needle is inserted on the inferiormedial border of the scapula aimed laterally. For the
superomedial bursa, the needle should be angled 45°
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FIGURE 4. (A-C) Various scapular on and scapular protraction
exercises.
laterally in a cephalad to caudad direction, entering
just off the superior-medial tip of the scapula (Fig
5).3,7 The maximum frequency of corticosteroid injec-
tions is usually 3 to 4 times per year.4 By combining
a local anesthetic agent with the steroid, injection is
both diagnostic and therapeutic. If there is pain relief,
SNAPPING SCAPULA
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OPERATIVE TREATMENT
Relevant Anatomy
Anatomic structures are at risk of injury during
operative intervention of snapping scapula and include
the long thoracic nerve, dorsal scapular artery, suprascapular nerve, axillary contents, and thoracic cavity.4
Knowledge of their location and avoidance of these
structures decreases surgical complications. Before
the incision is made, a skin marker may be used to
identify the inferior and superomedial corners of the
scapula, the medial border, the scapular spine, and the
acromion.16,36
Surgical incision, bony resection, and placement of
arthroscopic portals must be precise to avoid neurovascular structures. In the arthroscopic technique, 2
portals are placed on the medial border of the scapula
approximately 3 to 4 cm medial to the vertebral border
of the scapula and below the level of the scapular
spine to avoid injury to the dorsal scapular nerve and
artery and the accessory nerve.6,10-12,16,40,43,50 Placement of a third, superior portal must be methodical
because of the presence of multiple neurovascular
structures, including the accessory nerve, the suprascapular nerve, the dorsal scapular nerve, and the
transverse cervical artery, coursing nearby.11,12
Both open and arthroscopic procedures must avoid
the accessory and long thoracic nerves medially.36
Instrument orientation or bony resection either superiorly or laterally toward the coracoid process must
avoid the suprascapular nerve and artery located in the
suprascapular notch.4,27
FIGURE 5. The 2 common locations of scapular bursal injections
are at the superomedial border and at the inferior tip.
there is a high likelihood that scapular bursitis or
crepitus is the cause of the patient’s pain.1
Pearls
●
Initial activity modification, nonsteroidal anti-inflammatory drugs, and physical therapy are the
main components of a successful treatment approach.
● Physical therapy should focus on strengthening the
subscapularis and serratus anterior.
● Corticosteroid and anesthetic injection is a good
predictor of successful outcomes with either nonoperative or surgical intervention.
Open Surgical Approach and Technique
Partial scapulectomy is an option for treating symptomatic snapping scapula resistant to nonoperative
treatment.4,15 Not all cases require excision of the
superomedial section of the scapula. In studies in
which bursectomy alone was performed, excellent results were obtained.2,51 However, resection of the superomedial border more consistently produces successful results and is the more commonly used
method.36,52
Open bursectomy can be performed either at the
superomedial angle or at the inferior pole, the 2 most
common locations for scapulothoracic bursitis.12 Localization of the snapping or pain determines the site
for resection.25 Surgery on the inferior bursa is approached through an oblique incision distal to the
inferior angle of the scapula. The surgeon will split the
trapezius and latissimus dorsi in line with the muscle
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fibers to expose the bursa. Excision of the bursa with
removal of any osteophytes on the scapula is performed. The wound is then closed over a drain.4 For
superomedial bursitis, a vertical incision medial to the
medial border of the scapula is made. The trapezius is
dissected free and retracted cranially from the scapular
spine, followed by dissection of the levator scapulae,
subscapularis, and supraspinatus, which are retracted
proximally through subperiosteal dissection.4,9 The
bursa can then be resected and any osteophytes removed.4 The procedure ends with reapproximation of
the periscapular muscles.
Bony resection can improve surgical results.36
When no obvious bony lesion is noted, removal of the
medial 2 cm of the scapula allows a more natural
articulation of the scapulothoracic joint when the muscles are reattached.29 The medial scapular border contains the origin of the subscapularis, supraspinatus,
infraspinatus, serratus anterior, rhomboid, and levator
scapulae muscles. Their disruption with resection of
the entire medial border of the scapula can lead to
significant postoperative disability.26,28 More recently,
snapping scapula has been treated successfully with
excision of just the superomedial border of the scapula, avoiding the negative outcomes.9,12,15
To perform the superomedial scapular resection, the
patient is placed in the prone position, and an incision
over the medial scapular spine is made with dissection
through the soft tissue to expose the scapular spine.4,15
The periosteum is incised with subperiosteal elevation
of the medial periscapular muscles, including the supraspinatus, subscapularis, rhomboid, and levator
scapulae, which are retracted proximally.4,9,12,48 The
trapezius is retracted cranially.9,15 The superomedial
angle of the scapula is resected with an oscillating saw
in the shape of an equilateral triangle extending to the
medial base of the scapular spine.4,15,48 Elevated muscles are reapproximated to the spine of the scapula by
suturing them to the bone by use of drill holes.4,12,53
The affected arm is mobilized during surgery to confirm relief of the snapping. The wound is closed over
a drain (Fig 6).9
Pearls
●
Surgical treatment is reserved for patients with
painful, audible, and palpable crepitus not responding to nonoperative treatment.36
● Severe winging is a contraindication to surgical
resection of the superomedial scapula.36
Arthroscopic Approach and Technique
Arthroscopic treatment of snapping scapula is an
alternative that decreases the morbidity of the open
technique caused by muscle takedown. Cosmesis and
earlier rehabilitation with earlier return to full function
are other benefits.10,12,43,54 It is an effective and safe
procedure for bursectomy and resection of the superomedial corner of bone.50
Arthroscopic procedures were first described
using 2 portals placed 3 cm medial to the scapula,
but because of visibility limitations, the procedure
evolved to the more common recent practice of using
a third, superior portal. Some surgeons prefer to first
perform a shoulder arthroscopy to exclude other
causes of shoulder pain. Once this has been done, the
surgeon focuses on the scapulothoracic articulation. A
sterile stockinet is placed around the arm. The patient
is placed in the prone position with the arm in a
chicken-wing position by use of internal rotation. This
allows for easier access to the articulation because this
causes scapular winging.10,11,14,16,36,55 A spinal needle
may be placed at the superomedial corner of the
scapula to assist in orientation.14,36 One of the medial
portals is a viewing portal at the level of the spine, and
the other is a working portal inferior to the spine of the
scapula.10-12,16,40,50 The introducer is passed through
the skin, subcutaneous tissue, and trapezius; then between the rhomboid minor and rhomboid major at the
level of the spine of the scapula; and finally, into the
serratus anterior space. Entry to the subscapularis
space can be made by penetration of the serratus
anterior muscle. The potential pitfalls include overpenetration through the chest wall, causing pneumothorax, or penetration through the serratus anterior
into the axillary space.6,10,12,56
A third, superiorly located portal allows easier access for resection of the superomedial angle of the
scapula.36 To create this portal, instrumentation is passed
between the scapula and the thoracic cage and directed
caudal and medially. The portal is located one third of
the distance from the medial scapular border between the
superior medial angle of the scapula and the lateral
border of the acromion to avoid neurovascular
structures.11,16,36 When instrumentation is passed to
locate the third portal, care must be taken to remain
close to the ventral surface of the scapula to avoid
penetration of the thoracic cavity (Fig 7).11,16,36
Once portal placement is complete, the portal 3 cm
medial to the scapular spine is used as the viewing
portal with a 4.5-mm 30° arthroscope.10,12,36 Fluid
SNAPPING SCAPULA
1307
FIGURE 6. Open surgical approach for treatment of snapping scapula. (A) The patient is positioned prone, and the incision is made on the
medial border of the scapula, ensuring that the dorsal scapular nerve is protected. The trapezius and deltoid are identified along the scapular
spine (B) and retracted to see the periscapular muscles (C). (D) The levator scapulae and rhomboid are tagged and subperiosteally elevated
off the superomedial scapula border.
1308
M. KUHNE ET AL.
FIGURE 6. (Continued). (E) Approximately 1.5 cm of superomedial scapula bone is resected with a small oscillating saw and the bursa just
deep to the bone debrided. (F) Bone tunnels are drilled (1.5 mm) into the scapula to securely repair the levator scapulae and rhomboid with
No. 2 nonabsorbable suture. (G) Final repair.
pressure is introduced into the scapulothoracic space
to 50 mm Hg.40 The intercostal muscles and ribs
should be visualized inferiorly, the subscapularis laterally, and the rhomboids medially.14 A bipolar radiofrequency device is used to minimize bleeding.12 Resection of thin areolar tissue and fibrous bands with
the shaver creates a view of the subscapular bursa.
The thoracic surface of the superomedial scapula can
be identified by use of direct palpation and scapular
movement.10,40 Any fibrous adhesions that are encountered in the bursa between the subscapularis and
serratus anterior and in the bursa between the serratus
anterior and the chest wall should be debrided.4,55
Soft-tissue and bursal tissue from the deep surface of
the superomedial corner of the scapula is removed
with the shaver.16,36,57 Radiofrequency ablation is useful to skeletonize the bone.14
Once bursectomy is complete, the superomedial
corner of the scapula is resected. Meniscal and notchplasty burs are used to excise a triangular section of
the superomedial part of the scapula.10,16,36 To avoid
the suprascapular nerve, the surgeon should mark a
point on the medial border of the scapula halfway
between the scapular spine and the inferior pole. The
shaver is passed through the superior portal and
directed no more lateral than toward that point and
no more distal than the scapular spine, creating a
2.5-cm buffer to protect this nerve.36 Before removing the arthroscope, the surgeon should ensure that
there is full clearance of the scapula without impingement.10,40
Pearls
●
A 3-portal approach with care and preplanning
avoids neurovascular structures.
● Arthroscopic technique affords better cosmesis,
decreased morbidity, and a more rapid return to
full function than the open procedure.
● Two of the portals should be placed 3 cm medial
to the medial scapular border and caudal to the
spine of the scapula to avoid injury to the dorsal
scapular nerve and artery.
POSTOPERATIVE REHABILITATION
The course for postoperative physical therapy depends on whether the surgical technique was open or
arthroscopic. Arthroscopic surgery, with less muscle
disruption, allows a more rapid course of physical
rehabilitation with earlier return to full activities.
After open bursectomy on the inferior scapular
bursa, physical therapy is begun at 1 week. Because of
the increased dissection for superomedial bursectomy,
a longer postoperative course is needed. Passive motion and pendulum exercises can begin immediately
with a sling for comfort. Physical therapy continues
with active motion between 3 and 8 weeks and
strength training at 12 weeks.4,15
The open superomedial scapular resection postoperative course is of longer duration. A splint is placed
for 3 weeks.9 Rehabilitation is started with early passive motion and then active motion at 4 weeks, fol-
SNAPPING SCAPULA
1309
FIGURE 7. (A) For arthroscopic resection, the patient is
placed prone and the medial
border of the scapula is elevated off the thorax by internally rotating the arm up the
back. (B) The arthroscopic portals are approximately 3 cm
medial to the most medial edge
of the scapula to avoid injuring
the dorsal scapular and spinal
accessory nerves. (C) An additional portal may be made superiorly in the medial one third
of the scapula coming from superior to inferior to assist with
access to the superomedial
scapular border. (n, nerve.)
lowed by strengthening at 8 to 12 weeks.12 Resistance
exercises can then be started at 12 weeks.4
After arthroscopy, the patient uses a sling for 24
to 48 hours and then begins both passive and active
physiotherapy focused on thoracic posture, scapular
control, and rhomboid strengthening.10,36,40 Full active motion with the arthroscopic technique is expected by 1 week.16,36 In one study all patients
reported a reduction in pain and snapping at 6
weeks postoperatively.40 Full recovery can be expected by 2 to 4 weeks postoperatively.36 Even if a
full recovery has occurred, the return to sports and
overhead activities should not occur until 2 or 3
months postoperatively.10,16,36
Pearls
●
After arthroscopy, a full recovery is expected by
2 to 4 weeks with return to sports by 2 to 3
months.
● After an open procedure, longer physical therapy
and rehabilitation regimens are necessary because of the extent of surgical dissection.
● Physical therapy begins with passive motion, fol-
1310
M. KUHNE ET AL.
lowed by active motion and then strengthening
exercises.
OUTCOMES
The literature supports nonoperative treatment as
the initial treatment for patients with snapping scapula. Approximately 50% of patients, with the rate
being as high as 80% in some studies, had relief of
symptoms with nonoperative treatment.5,9,55 When
this fails, surgical interventions have a high success
rate. In one study 50% of the patients who underwent
open surgical resection had relief of symptoms at 1
year.5 Other studies showed a higher success rate. One
study showed that 12 of 14 patients had relief of pain
and snapping at a mean of 42 months after surgery,48
and another had an 88% success rate.4 In these studies
no gross anatomic abnormalities of the resected portion of the scapula were noted. Another study described 5 patients who underwent surgery, all of
whom returned to normal activities, although 1 reported incomplete resolution of symptoms.9 Three patients with osteochondroma underwent surgical excision, all with good results.
In a study using the arthroscopic approach with 2
portals, the authors reported that 95% of patients
would undergo the procedure again and 22 of 23
patients had good or excellent results.51 Among the
23 patients, there were no surgical complications. All
patients were able to return to their previous activities.
In studies involving the arthroscopic approach with
the third portal, the procedure was found to be safe
and successful. No intraoperative or postoperative
complications were found with this surgical approach.
Although the studied patient population remains
small, the results are promising. Among 26 patients,
all with normal radiographs before surgery, only 1 had
symptoms that were not improved after surgery. However, all patients reported that the procedure was
worthwhile. Although their pain was resolved, 25% of
the patients continued to have mild crepitus with occasional clicking.16,36,58 In one study of 10 patients,
only 1 patient remained unable to return to work
duties and 7 returned to their sporting activities.16
CONCLUSIONS
Snapping scapula is caused by a disruption in the
normal mechanics of the scapulothoracic articulation.
Once neurogenic disorders and disorders of the acromioclavicular and glenohumeral joints are excluded, the
etiology of the crepitus must be determined through
history, physical examination, and radiologic studies. If
there is an obvious anatomic cause for the snapping,
nonoperative treatment should be trialed with likely progression to surgical excision of the abnormality. If no
anatomic lesions are noted, conservative treatments
should be trialed first, but if unsuccessful, both open and
arthroscopic procedures for excision of the superomedial
scapular border have been proven to provide relief of
these patients’ symptoms.
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