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Snapping Scapula Syndrome
Meredith A. Lazar, Young W. Kwon and Andrew S. Rokito
J Bone Joint Surg Am. 2009;91:2251-2262. doi:10.2106/JBJS.H.01347
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The Journal of Bone and Joint Surgery
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C OPYRIGHT 2009
BY
T HE J OURNAL
OF
B ONE
AND J OINT
S URGERY, I NCORPORATED
Current Concepts Review
Snapping Scapula Syndrome
By Meredith A. Lazar, MD, Young W. Kwon, MD, PhD, and Andrew S. Rokito, MD
ä
Snapping scapula syndrome arises from either a soft-tissue or a skeletal anomaly within the scapulothoracic
space that creates a cracking sound during scapulothoracic motion that patients associate with pain.
ä
Nonoperative measures consisting of supervised physical therapy, anti-inflammatory medications, and therapeutic injections are the mainstay of treatment.
ä
Open, arthroscopic, and combined operative approaches have been described for the treatment of refractory
cases, with good overall outcomes in many relatively small case series. However, the optimal operative approach
has yet to be determined.
Snapping scapula syndrome, also known as scapulothoracic crepitus or bursitis, was first described in 1867 by Boinet1. The severity
of the sounds associated with this syndrome were stratified by
Mauclaire in 1904 as froissement (rustling), frottement (rubbing), or craquement (cracking), the latter of which was used to
denote a sound so loud it must be pathological2. The sound is
produced by a tactile-acoustic phenomenon occurring as a consequence of an anomalous tissue between the thoracic wall and
the scapula. While most patients deem these sounds as a peculiar
irregularity that does not produce symptoms, some report a clear
correlation between the sounds and pain3. With an increasing
knowledge base and advancing surgical technology, the available
treatment modalities for such patients are continuing to evolve.
This review will discuss the current approach to the diagnosis
and treatment of patients with snapping scapula syndrome.
Anatomy and Function of the Scapulothoracic Joint
The scapula is a large, flat, triangular bone that lies along the
posterior surface of the thoracic cage between the second and
seventh ribs. It has two surfaces (ventral and dorsal), three borders (superior, axillary, and vertebral), and three angles (superomedial, inferomedial, and lateral)4. The scapula, in its static
resting position, lies approximately 5 cm lateral to the spine on
the posterior aspect of the thorax, is angled 30 to 40 in relation
to the coronal plane, and is tipped anteriorly 10 to 20 with
respect to the sagittal plane5. The scapula is part of the superior
shoulder suspensory complex, which provides attachments to
the axial skeleton. Its only skeletal connections are the acromi-
oclavicular and coracoclavicular ligaments. Consequently, the
scapula relies primarily on the surrounding muscles for support
and stability. The contour of the scapula may vary, and, in one
anatomic study, abnormalities were consistently found at the
superomedial and inferior poles of the scapula6.
The articulation between the scapula and the thoracic
cage is one of the most incongruent in the human body. The
scapulothoracic pseudojoint has three layers: superficial, intermediate, and deep7. Each layer consists of muscles and
bursae. The superficial layer comprises the trapezius and latissimus dorsi muscles (Fig. 1). This layer can be associated
with a well-circumscribed inferior angle bursa, measuring 1.9 ·
2.4 cm on the average, located between the inferomedial angle
of the scapula and the superficial fibers of the latissimus dorsi
muscle7. The intermediate layer consists of the rhomboid
major, rhomboid minor, and levator scapulae muscles. The
trapezial bursa lies between the trapezius muscle and the base
of the scapular spine and averages 4.3 · 2.7 cm in size. This
bursa is particularly important as it provides a smooth surface
over which the scapula rotates.
In the intermediate layer, along with the trapezial bursa,
is the spinal accessory nerve, which crosses the superior border
of the scapula approximately 2.7 cm lateral to its superomedial
angle as it enters the interval between the superomedial angle
and the trapezius muscle just lateral to the levator scapulae
muscle7. The dorsal scapular nerve is also in this vicinity as it
enters the scapulothoracic region and travels deep to or
through the levator scapulae parallel to the medial border of
Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a
member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial
entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice,
or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.
J Bone Joint Surg Am. 2009;91:2251-62
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Fig. 1
Posterior view of the superficial layer of the scapulothoracic joint. The borders and angles
of the scapula are identified, as are the spinal accessory nerve, the dorsal scapular
nerve, and the suprascapular nerve.
the scapula before innervating the rhomboid muscles8. The
transverse cervical artery is divided by the levator scapulae
muscle into the dorsal scapular artery and a branch that runs
with the spinal accessory nerve9. The suprascapular nerve is
also in proximity as it travels obliquely across the superomedial
angle and superior border of the scapula and courses toward
the suprascapular notch10. These structures are all at risk during operative treatment of scapulothoracic bursitis and must
be carefully avoided during dissection9.
The deep layer consists of the serratus anterior and subscapularis muscles and contains two discrete major bursae
(Figs. 2-A and 2-B). The scapulothoracic, or supraserratus,
bursa is located between the serratus anterior muscle and the
thoracic cage and averages 9 · 7.4 cm in size. The subscapularis, or infraserratus, bursa is located between the serratus
anterior and subscapularis muscles, is inconsistently present,
and averages 5.3 · 5.3 cm7.
The scapula plays a crucial role in the function of the upper
extremity by providing a stable base for glenohumeral motion. In
addition, the scapula glides against the thoracic wall to augment
shoulder motion. Scapular motion is required to maintain optimal muscle length-tension relationships and alignment of the
glenohumeral joint during elevation of the upper extremity11.
Biomechanical analyses of normal scapular motion have revealed that the scapula can simultaneously rotate and translate
along three axes to support glenohumeral motion12. The ratio of
glenohumeral to scapulothoracic movement (GH/ST ratio) in
various planes has been extensively studied and has been shown
to be approximately 2:1 in both forward flexion and abduction.
However, among the various planes, the GH/ST ratio has been
found to vary in a nonlinear fashion depending on the position
of the arm relative to the scapula. Several studies have shown the
GH/ST ratio to range from 1.25 to 3.2, with the ratio in forward
flexion being slightly higher on average than the ratio in abduction11,13,14. Specific rehabilitation protocols for stretching and
strengthening the pectoral muscles, scapular retractors and elevators, and glenohumeral abductors and external rotators can
increase the GH/ST ratio, which promotes scapular stability and
improves glenohumeral motion15.
Pathophysiology of Scapulothoracic Bursitis
Scapulothoracic bursitis may occur following a single traumatic
insult or as a result of a series of repetitive motions of the scapulothoracic joint16-18. In most cases, the bursitis is believed to be
caused by abnormal motion between the anterior surface of the
scapula and the thoracic cage. In 1933, Milch and Burman re-
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Fig. 2-A
Fig. 2-B
Anterior (Fig. 2-A) and cross-sectional (Fig. 2-B) views of the deep bursae in the scapulothoracic joint:
the scapulothoracic and subscapularis bursae.
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ported on a small series of patients with scapulothoracic bursitis
and suggested that the pain was caused by an abnormal forward
curvature of the superomedial angle of the scapula due to various skeletal or soft-tissue abnormalities19.
Scapulothoracic crepitus may be produced by an unusual
shape of the scapula19. In a cadaver study, bending of >35 was
noted in 8.6% (sixty) of 700 specimens6. Approximately 6% of
scapulae demonstrate a hook-shaped prominence, known as
the Luschka tubercle, at their superomedial angle6. This tubercle
may enlarge and articulate with the thoracic cage, resulting in
painful crepitus6. However, a clear causal relationship between
this morphology and the presence of scapulothoracic bursitis
has not been demonstrated.
Osteochondroma is the most prevalent benign tumor of the
scapula and has been implicated as a common cause of snapping
scapula syndrome20-22. An extensive review of the literature
identified eighty-nine cases of snapping scapula syndrome, with
osteochondroma being the cause in 16% (fourteen)21. Other, less
common, skeletal causes of scapulothoracic crepitus include
skeletal exostoses and other osseous tumors, especially if they
arise from the ventral surface of the scapula, and fracture
malunion of either the ribs or the scapula23,24. The scapula is
the second most frequent location of chondrosarcoma, which
must be considered in the differential diagnosis of lesions in
the scapulothoracic space25.
Scapulothoracic bursitis may also occur following loss of
dynamic control of scapular motion 26 . Abnormal scapular
motion can be caused by muscle overuse, muscle imbalance
following nerve injury, or pathological conditions of the glenohumeral joint27. Scapular dyskinesis has been observed in
patients with known glenohumeral joint pathology and in
specific series has been reported of fourteen of twenty-two
patients with shoulder instability 28, seven of seven patients
with impingement28, and fifteen of fifteen patients with rotator
cuff abnormalities29,30 . Muscle atrophy secondary to nerve
injury, trauma, or prior operative treatment can lead to diminished soft-tissue interposition between the scapula and the
thoracic cage, resulting in scapulothoracic crepitus and pain5.
When soft-tissue interposition is diminished, the scapula tilts,
and thus a normally shaped scapula can appear to have an
abnormally curved shape and dig into the chest wall31. The
superomedial angle of the scapula then impinges along the chest
wall during scapulothoracic motion and creates inflammation
in the scapulothoracic space. Atrophy of the serratus anterior
following injury to the long thoracic nerve as well as subscapularis atrophy in patients with thoracic outlet syndrome have
also been implicated as etiologies of scapulothoracic crepitus32.
Normal scapular motion along the thoracic cage is
particularly important to athletes, and a history of overuse
during activities such as swimming, pitching, weight training,
gymnastics, and football has been implicated in the onset of
symptoms5,33.
A phenomenon described in pitchers known as SICK
(scapular malposition, inferior medial border prominence,
coracoid pain and malposition, and dyskinesis of scapular
movement) has recently been recognized as an overuse mus-
cular fatigue syndrome that has many of the same features as
scapulothoracic bursitis34.
Other causes of scapulothoracic bursitis include prior
operative treatment that violated the periscapular musculature32. For example, in one series, snapping scapula syndrome
developed in fifteen of 100 patients in whom thoracic outlet
syndrome had been treated with resection of the first rib32. We
have observed scapulothoracic bursitis in women who have
undergone cosmetic breast procedures that involved subserratus exploration with implant placement.
Clinical Presentation
History
Patients with snapping scapula syndrome who seek medical
treatment primarily report activity-related pain and crepitus.
These symptoms may have an insidious onset, occur after a
change in activity pattern, or be associated with trauma21. The
clinician should identify possible precipitating factors and
question the patient regarding the duration and severity of the
symptoms. In addition, symptoms such as shoulder girdle or
neck pain and weakness should be documented. Other relevant elements of the history include hand dominance, occupation, and activity level, which may help to reveal causative
factors. Crepitus associated with a soft-tissue lesion or muscle
imbalance is typically softer than that associated with a skeletal
lesion35. In addition, skeletal lesions may initially present with
subtle findings such as a painless, enlarging mass that does not
cause crepitus and that can be misdiagnosed as scapulothoracic
bursitis36,37. In the absence of an identifiable lesion, the clinician must inquire about the frequency, level, and character of
sports activities because those who engage in repetitive throwing,
swimming, gymnastics, or weight-lifting are particularly susceptible to the development of scapular dyskinesis or bursitis34.
Physical Examination
The spine must first be inspected for any excessive curvature as this
will create an abnormal contour about the thoracic cage, which in
turn will directly alter scapular motion30. In one series, six of nine
patients diagnosed with snapping scapula syndrome demonstrated kyphosis of the upper thoracic spine with no history of
Scheuermann adolescent kyphoscoliosis38. Other postural conditions that have been associated with scapulothoracic dysfunction include a forward-tilted head, rounded shoulders, abducted
and forward-tipped scapulae, and suboccipital extension. Patients should also be assessed for sources of referred pain,
including cervical radiculopathy, neurological injuries, and
pathological changes in the glenohumeral joint39.
The shoulder girdle should then be inspected for any
scapular asymmetry. This can be subtle and its identification
can require careful assessment. In the presence of scapular
dysfunction resulting from a nerve injury, patients have difficulty abducting the arm and may compensate by shifting the
entire trunk in order to perform tasks that require arm abduction25. The position of the scapula should be documented
during both ascending and descending shoulder motions as
well as during scapular protraction, retraction, and rotation34.
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Fig. 3
This patient with an osteochondroma on the right scapula
demonstrates scapular asymmetry with maximum internal rotation.
Palpation of the periscapular region may reveal focal
tenderness at the medial scapular border over the superomedial and/or inferomedial bursae. Adduction and internal
rotation of the shoulder allow these borders to be accessed for
easier palpation5. Patients often know how to reproduce the
snapping by elevating and depressing the shoulder, and when
they do so the crepitus can be localized from the undersurface
of the scapula25. The active and passive ranges of motion of the
shoulder should be carefully examined for any limitations.
The strength of the scapular musculature, specifically the
trapezius, rhomboids, levator scapulae, serratus anterior, and
latissimus dorsi muscles, should also be assessed30. The trapezius muscle strength is evaluated by having the patient shrug
the shoulders against resistance. The rhomboids and levator
scapulae can be tested by having the patient place the hands on
the hips and push the elbows backward against resistance. The
serratus anterior is assessed by having the patient press against
a wall with an outstretched arm while the examiner palpates
the scapula for winging. The latissimus dorsi is tested with
downward and backward pressure of the arm against resistance
while the examiner palpates the inferomedial angle of the
scapula. However, static manual muscle testing may not be
sufficiently sensitive to detect subtle weakness in these muscles.
It is thus critically important to characterize the dynamic
motion of the scapula28. Scapular motion can be characterized
by the position of the inferomedial or superomedial angle and
by the plane in which it rotates—coronal or sagittal12.
In the presence of a lesion, so-called clunking may
be observed when the arm is abducted from 90 to 18020.
Pseudo-winging of the scapula can be observed if a skeletal
lesion pushes against the thorax to displace the scapula away
from the body (Fig. 3)40.
Weakness in the major scapular stabilizers (serratus anterior, trapezius, and rhomboid muscles) may present as different patterns of scapular winging. An injury of the long
thoracic nerve causing atrophy of the serratus anterior results
in lateral scapular winging. Injury to the spinal accessory nerve
that results in trapezius atrophy may cause the shoulder to
droop or rotate forward more medially and is often more subtle
than the winging associated with dysfunction of the serratus
anterior. Scapular winging becomes more evident with motion
and stress testing. To evaluate for scapular winging, the examiner should observe the scapula and palpate the inferomedial
angle during elevation. The scapula should also be observed
while the patient pushes against a wall or performs a push-up,
as these maneuvers accentuate the asymmetric movement of
the scapula25. If a neurological injury is suspected, electrodiagnostic studies (electromyography and/or measurement of
nerve conduction velocities) can be performed to determine
whether the results correlate with those of the clinical
examination41.
Posterior capsular tightness may also be present, especially in throwing athletes. Evaluating external and internal
rotation of both shoulders with the humerus at 90 in the
coronal plane is useful to assess capsular tightness42. The upper
trapezius and the pectoralis minor are other common sites of
myofascial tightness. Hypertonia in athletes with shoulder pain
can also contribute to scapular dyskinesis43.
Imaging
Imaging modalities used in the evaluation of snapping scapula
syndrome include plain radiographs, computed tomography,
magnetic resonance imaging, and ultrasonography. Standard
radiographs of the scapula include a true anteroposterior view
(with the scapula lying flat against the cassette or the beam tilted
to account for the scapular angle), a tangential transscapular (or
Y) view (with the beam pointed in line with the spine of the
scapula), and an axillary lateral view (to assess the glenohumeral
joint). These projections help identify skeletal irregularities
such as osteochondromas, a Luschka tubercle, rib abnormalities, or alterations at the superomedial or inferomedial angle of
the scapula (Fig. 4)6. Lesions that arise from the ventral surface
of the scapula are particularly apparent in the scapulothoracic
space on the Y view, as are sagittal plane deformities at the
superomedial or inferomedial angle. Unfortunately, these
lesions are not always readily visible on radiographs, and fluoroscopy has been suggested as an adjunctive tool to dynamically visualize the grating or snapping of the scapula23. Several
case reports have documented the utility of cineradiography
to identify skeletal lesions in patients with scapulothoracic
crepitus44.
The efficacy of computed tomography scanning for the
routine evaluation of scapulothoracic crepitus has remained
controversial. While a retrospective study did demonstrate
high intraobserver and interobserver agreement with regard
to the assessment of computed tomography scans for scapular
crepitus, the interpretations of these scans did not correlate
well with the clinical findings45. Therefore, the authors suggested that the routine use of computed tomography was not
justified for patients with the clinical diagnosis of scapulothoracic crepitus45. Similarly, a more recent study demon-
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tion47. Thus far, however, the use of ultrasound for diagnosis or
treatment of scapulothoracic crepitus appears to be infrequent
and published data are mostly limited to case reports47,48.
Fig. 4
Tangential radiograph of a scapular
osteochondroma (arrow), demonstrating how these lesions may encroach on the scapulothoracic
space and cause bursitis.
strated fairly poor correlation between findings on computed
tomography scans and clinical symptoms46. The authors of that
study also noted that computed tomography scans, especially
three-dimensional reconstructions, were reliable in detecting
abnormalities and incongruities between the scapula and the
thoracic cage in multiple planes, suggesting that these images
may be important adjuncts to plain radiographs for the
planning of operative treatment of scapulothoracic crepitus.
Given these findings, we believe that a computed tomography
scan would be a useful adjunct to plain radiographs if a bone or
cartilage lesion is visible and requires further characterization
for preoperative planning (Fig. 5).
Magnetic resonance imaging is better than computed
tomography scans for identifying and characterizing soft-tissue
masses. Higuchi et al. reported their experience with using
magnetic resonance imaging to evaluate scapulothoracic bursitis and found it to be more useful than computed tomography scans for assessing fluid-filled bursal tissue as well as for
distinguishing scapulothoracic bursitis from elastofibroma36.
They and other authors37 concluded that magnetic resonance
imaging is a valuable tool for assessing these so-called pseudotumors in the scapulothoracic bursa.
Ultrasound has also been used to identify and treat
scapulothoracic pathology. Specifically, by identifying the bursal tissue dynamically, it can be used for image-guided injec-
Nonoperative Treatment
The majority of patients with scapulothoracic crepitus or bursitis can be managed successfully without operative treatment.
An operation is required only for patients who have a clearly
identifiable osseous or soft-tissue mass. Nonoperative treatment
options include physical therapy, anti-inflammatory medications, and corticosteroid injections49.
The goals of rehabilitation for patients with snapping
scapula syndrome are improving muscle strength and balance,
addressing postural conditions (such as excessive thoracic
kyphosis), and core strengthening30,34,50. It is believed that poor
posture with the head and shoulders tipped forward causes the
posterior scapular stabilizers to weaken relative to the anterior
pectoral muscles, which leads to imbalances that may change
the scapular resting position and decrease scapular elevation15.
Kibler and McMullen identified three stages of rehabilitation
based on a program in which the shoulder is considered to be
part of a kinetic chain system30. The kinetic chain model depicts the body as a system of interdependent parts that work in
a proximal-to-distal sequence to impart a desired action at
the distal segment. In kinetic chain shoulder rehabilitation, the
lower limbs and the trunk are integrated into most of the
exercises, which reinforces normal movement patterns from
the outset43. Arm elevation requires full scapular retraction,
which is incumbent on spine and hip extension to accommodate scapular motion. Therefore, shoulder function is
dependent on thoracic spinal control, which must be reestablished with physical therapy prior to strengthening individual shoulder muscles43. Lower scapular stabilization can be
Fig. 5
Three-dimensional computed tomography reconstruction
in the coronal plane, demonstrating an osteochondroma
(arrow) along the anterior surface of the scapula.
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facilitated through contraction of the contralateral gluteus
maximus muscles through the thoracolumbar fascia, which
connects to the latissimus dorsi muscle. Efficient shoulder
motion and muscle activation occur in this proximal-to
distal sequence, which is the basis for the ten-week rehabilitation protocol. The program progresses in a stepwise
fashion from the acute phase (zero to three weeks), to the
recovery phase (three to eight weeks), and finally to the
maintenance phase (six to ten weeks) with specific exercises
prescribed at each interval, bearing in mind that function,
rather than time, determines a patient’s overall progress with
this protocol30.
In the acute phase, the goal of rehabilitation is to reduce
pain. Consequently, those movements and positions associated
with discomfort are limited. Trunk flexion and rotation exercises are performed so that scapular motion can be achieved
without moving the arm, which may be painful. Patients are
instructed to perform so-called safe co-contractions, in which
the hand is supported so that the gravitational force on the arm
is eliminated and pain is minimized51. Abnormal scapular
motion has been attributed to excessive activation of the upper
trapezius muscle combined with decreased control of the lower
trapezius and the serratus anterior muscle. To restore muscle
control and balanced coactivation, exercises that selectively
recruit weaker muscles over hyperactive muscles are recommended52. Stretching maneuvers are performed in conjunction
with closed-kinetic-chain exercises, in which the hand is relatively fixed (such as in modified push-ups) and which require
less muscle activation than open-chain exercises (dumbbell
press and machine-rowing)30,51.
In the recovery phase of rehabilitation, strengthening is
performed with motion, which is dependent on the proper posture that has already been established in the acute phase. Closedkinetic-chain exercises are advanced and should be performed
in multiple planes and levels of elevation to reproduce scapular
motion in its varied positions. Cools et al. performed an electromyographic study to elucidate which shoulder girdle exercises
selectively activate middle and lower portions of the trapezius and
serratus anterior muscles over the upper trapezius muscle to
restore balance to the scapulothoracic musculature52. Side-lying
forward flexion, side-lying external rotation, and prone horizontal abduction with external rotation all had favorable upperto-lower trapezius-muscle recruitment ratios (Figs. 6-A, 6-B,
and 6-C). These arm elevation and rotation exercises should be
added and weights should be increased as tolerated by the
patient during this recovery phase of rehabilitation. Exercises
are also performed to continue to strengthen the kinetic chain.
Core strength endurance training helps to facilitate dynamic
postural control for prolonged periods of time5.
The maintenance phase begins once good scapular
control and motion have been achieved. Plyometric (dynamic
stretch-shortening) exercises such as tossing a medicine ball
and open-chain exercises such as the walking lunge with a
shoulder dumbbell press are advanced and integrated. Performance of strengthening exercises in various planes while
loading the glenohumeral joint is also prescribed30.
Fig. 6-A
Fig. 6-B
Fig. 6-c
Figs. 6-A, 6-B, and 6-C Exercises that selectively restore trapezial
52
muscle balance . Fig. 6-A Side-lying forward flexion. Fig. 6-B
Side-lying external rotation. Fig. 6-C Prone abduction and external
rotation.
Ciullo reported excellent results in sixty-two of seventytwo patients treated with a combination of diathermy, ultrasound, and iontophoresis along with periscapular and rotator
cuff muscle strengthening 53. In another study, Groh et al. found
good or excellent results in twenty-two of thirty patients treated
with periscapular muscle strengthening50.
A corticosteroid and/or local anesthetic can be injected
into the scapulothoracic bursa for diagnostic and therapeutic
purposes. These injections are best administered with the patient prone and in the so-called chicken-wing position, with
the shoulder extended and internally rotated to elevate the
medial border of the scapula (Fig. 7)49. Care must be taken to
direct the needle parallel to the chest wall as pneumothorax is a
potential complication35. The injection should be directed to-
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clinical benefits of this modality have not been demonstrated,
however.
Operative Treatment
Indications
Operative management may be considered for patients who
have undergone a prolonged course of nonoperative treatment
with little or no improvement16,56-60. Ideally, these patients should
be able to localize the pain to the superomedial or inferomedial
angle of the scapula. The operative outcome is more reliable if
the diagnosis can be confirmed with a preoperative injection of
local anesthetic5,55,58. Lehtinen et al. suggested that failure to
receive at least temporary relief from an injection should be
a relative contraindication to operative management26. Other
relative predictors of a poor operative outcome include the
ability to voluntarily produce the snapping sound from the
scapula, involvement in a Workers’ Compensation claim or
litigation, and documented nerve deficits5.
Fig. 7
The so-called chicken-wing position elevates and defines the potential
space for injection at the superior or inferior (arrow) bursa.
ward the superomedial or inferomedial angle of the scapula,
depending on the location of the pain and the point of maximal tenderness.
Hodler et al. investigated the efficacy and accuracy of
injections for the treatment of scapulothoracic bursitis54. In a
study of twenty patients who received injections, eighteen reported improvement. The injection site was sterilized, and the
skin and needle track were anesthetized with 1% lidocaine. A
22 or 25-gauge 9-cm needle was inserted until the pain was
triggered. After location of the bursa under fluoroscopy, lidocaine and contrast medium were injected; this was followed
by injection of betamethasone and bupivacaine. The contrast
medium was injected as part of the study protocol to assess the
accuracy of the injection and identify the presence of a true
bursal sac. In seven patients, the contrast medium filled a
smooth, well-defined bursal sac. In eight patients, the injection
was placed intramuscularly as demonstrated by diffuse spreading of the contrast medium. In the remaining five patients,
some of the contrast medium pooled into a well-defined bursa
and some spread diffusely. The eighteen successfully treated
patients had a significant improvement in the visual analog
pain scores that lasted from six hours to fifteen months. The
authors concluded that injections are a safe and effective way
to treat scapulothoracic bursitis. In addition, even patients
without a well-defined bursa may have relief of pain after a
localized injection54. Other authors have reported similar efficacy of corticosteroid injections administered to provide
temporary relief prior to surgical treatment16,26,55.
The use of ultrasound-guided injections is currently
under investigation. Its perceived advantage is better visualization of the soft tissues, including adhesions, scarring, and
bursal collections, to facilitate more accurate injections47. Clear
Open Techniques and Results
To our knowledge, the first report of operative treatment for
snapping scapula was published in 19503. The procedure was
performed with the use of local anesthesia in three patients
who were asked to move the shoulder during the operation
in order to identify the portion of the scapula responsible
for the symptoms so that it could be resected. Subsequent
studies have shown good outcomes following open partial
scapular resection, usually for treatment of a distinct osseous
abnormality 21,23,44,55,59,61.
The procedure is typically performed with the patient in
either the prone or the lateral decubitus position with the involved extremity draped free. With internal rotation of the
shoulder, the medial border of the scapula can be lifted away
from the thoracic cavity. The location of the skin incision is
vertical, is in line with the medial border of the scapula, and is
centered either superiorly or inferiorly depending on the site of
the primary pathological findings. For operative dissection of
the superomedial angle of the scapula (Fig. 8), the trapezius
muscle may be split in line with its fibers over the scapular
spine to expose the underlying structures. During this portion
of the procedure, it is imperative to protect the spinal accessory
nerve, which crosses the superior border of the scapula just
lateral to the superomedial angle—i.e., between the superomedial angle and the trapezius muscle just lateral to the levator scapulae7. The levator scapulae and rhomboid muscles
can be released subperiosteally as needed to expose the anteromedial border of the scapula. Care must be taken when the
rhomboids are detached to avoid injury to the dorsal scapular
nerve, which is approximately 2 cm medial to the medial
scapular edge26. Finally, the involved osseous anomaly and/or
the inflamed bursae can be isolated and resected. With this
approach, the rhomboids are detached subperiosteally in order
to preserve the short Sharpey fibers of the tendinous insertions, which may be reattached through drill holes to their
appropriate position55. Although postoperative regimens may
vary, most authors have recommended a period of immobili-
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Fig. 8
Technique for open resection of the superomedial angle of the scapula. a: A
longitudinal incision is made along the medial scapular edge, and subcutaneous
undermining exposes the trapezius muscle, which is split and elevated in line
with its fibers over the medial aspect of the scapula. b: The rhomboid and levator
muscles are detached from the medial and superior edge to expose the superomedial edge of the scapula. c: The rotator cuff muscles are elevated in the
subperiosteal plane so that the bone is exposed completely. d: The exposed
portion of bone is removed. e: The muscles are then reattached through bone
tunnels to their anatomic insertion on the scapula. (Reprinted, with permission,
from: Lehtinen JT, Macy JC, Cassinelli E, Warner JJ. The painful scapulothoracic
articulation: surgical management. Clin Orthop Relat Res. 2004;423:99-105.)
zation in a sling for up to four weeks to allow the muscles to
heal to the bone, followed by exercises for restoration of the
range of motion and for strengthening26,27,33,55,56.
Open treatment for scapulothoracic crepitus and bursitis
has resulted in good-to-excellent outcomes in the majority of
patients18,33,56,62. McCluskey and Bigliani treated nine patients
with refractory scapulothoracic bursitis at the supraserratus
bursa with isolated open bursectomy 56. Fibrotic bursal tissue
between the serratus anterior muscle and the thoracic cavity
was excised. They reported six excellent and two good results.
The remaining patient experienced a spinal accessory nerve
deficit that required a tendon transfer, and only a fair outcome
was achieved.
More recently, Nicholson and Duckworth reported on
seventeen patients in whom scapulothoracic pain had been
treated with an open operative technique55. All of their patients
had a satisfactory outcome after an average duration of followup of 2.5 years. In addition to removal of bursal tissue, the
superomedial angle of the scapula was resected in five patients.
The authors noted that open osseous resection was able to
address other abnormalities about the area as well as provide
easy access to the trapezial bursa55. In this and other series in
which removal of a portion of the superomedial angle was
reported, gross and histological examination showed the resected bone to be essentially normal18,44,55,59.
Like resection for the treatment of supraserratus bursitis,
operative treatment of inferomedial scapulothoracic bursitis
has yielded satisfactory outcomes. In a small series of four
professional baseball pitchers, Sisto and Jobe performed an
open bursectomy at the inferior angle of the scapula33. Histological evaluation of the resected tissue revealed evidence of
chronic inflammation. All patients experienced complete or
nearly complete relief of symptoms and were able to return to
baseball at their previous level of competition.
Arthroscopic Techniques and Results
Although technically demanding, arthroscopic surgery for
snapping scapula syndrome offers several theoretical advantages over open operative treatment. These include minimizing
dissection and preserving muscle attachments, thereby eliminating the need for postoperative immobilization and potentially shortening the rehabilitation period58. Other advantages
include an improved cosmetic appearance and potentially
decreased hospital stays.
The patient is usually positioned prone with the arm
extended and internally rotated to accentuate the medial
border of the scapula49. Some authors have recommended the
lateral decubitus position as it allows concurrent evaluation of
the glenohumeral joint10. Once the patient is positioned, the
osseous landmarks are marked on the skin in anticipation of
portal placement (Fig. 9).
All standard portals should be established at least 3 cm
medial to the medial border of the scapula to avoid injuring the
dorsal scapular nerve and vessels. Along the vertical axis, the
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Fig. 9
Arthroscopic landmarks and portal placement. The superior visualization portal is 3 cm medial to the medial border of the
scapula just inferior to the scapular spine, and the inferior
working portal is made midway between the spine and the inferomedial angle.
superior visualization portal should be placed just inferior to
the scapular spine to allow access to both the superomedial and
the inferomedial angle of the scapula. Under arthroscopic visualization, the inferior working portal is then created midway
between the scapular spine and the inferomedial scapular angle. The instruments should point away from the coracoid
process to prevent damage to the suprascapular nerve and
vessels, which travel just medial to the base of the coracoid9.
The visualization and working portals may be interchanged as
needed intraoperatively for improved access to the bursal tissues. Portals placed superior to the scapular spine may result in
injury to the dorsal scapular nerve and vessels or the spinal
accessory nerve, and should be avoided.
If access to the superomedial angle of the scapula from
these portals is limited, a second working portal can be created
superiorly and laterally. With use of a so-called inside-out
technique, this superolateral portal can be located along the
superior border of the scapula at a distance that is one-third of
the distance between the superomedial angle and the acromion. Cadaver dissection and clinical outcome studies have
demonstrated that this portal can be established without excessive risk to the suprascapular nerve and vessels10,17.
During the bursectomy, it is important to maintain a
proper orientation relative to the thoracic cavity and clearly
identify the soft-tissue structures prior to débridement49. In
some patients, the bursal tissue is easily identifiable while, in
others, the tissue appears to be thickened or fibrotic (Fig. 10).
An advantage to arthroscopic débridement is that the periosteal sleeve of the rhomboid attachment is maintained, which
avoids the need for muscle reattachment and thus eliminates
the necessity for postoperative immobilization26.
After the bursectomy is completed, the arm may be
moved under direct visualization by the surgeon and if the
superomedial angle is deemed prominent a partial scapular
resection can be performed. If there is no prominence, the
scapulothoracic space may be temporarily deflated by removing
all of the arthroscopy fluid. An examination may then be performed with the patient under anesthesia to determine if the
superomedial angle of the scapula impinges on deeper structures16. If there is osseous impingement, the scapula can then
be skeletonized with a radiofrequency tissue ablator, and the
superomedial angle can be resected with use of a high-speed
burr. Although the exact extent of bone resection has been
debated, most authors have recommended removing 2 to 3 cm
of bone from the superomedial corner of the scapula26,44,63.
Before the procedure is completed, the scapulothoracic joint
should be examined with the patient under anesthesia to ensure that no impinging structures remain.
Most reports on the outcomes of arthroscopic surgery
for scapulothoracic bursitis and crepitus are small case series
with short-term follow-up. In general, however, good-toexcellent results have been reported in the majority of patients.
Failures have been attributed mostly to poor patient selection
and technical difficulties16,17,53,58.
In a recent longer-term follow-up study, thirteen patients underwent arthroscopic scapulothoracic bursectomy
with or without bone resection of the superomedial angle16. At
a mean of 6.8 years following surgery, all patients still reported
Fig. 10
Intraoperative photograph showing arthroscopic débridement of the
scapulothoracic bursa. The inflamed bursal tissue is removed from the
scapula and débrided from the subscapularis muscle.
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some degree of scapulothoracic crepitus. Nine of the thirteen
patients, however, reported less pain and improved function.
The authors, therefore, suggested that residual scapulothoracic
crepitus does not preclude a satisfactory outcome. In addition,
they emphasized the importance of patient selection as their
four patients with a failure included those with a history of
drug abuse, C7 radiculopathy with clear scapular winging, and
severe thoracic scoliosis16.
Combined Techniques and Results
Although the specific indications are still unclear, a combined
arthroscopic and open approach may be appropriate for some
patients. Bursectomy allows débridement of all inflamed tissue
that may be the source of pain, and partial scapular resection
(when indicated on the basis of the intraoperative examination) relieves the osseous impingement that contributes to the
bursitis. Lehtinen et al. reported on sixteen patients with
scapulothoracic bursitis and crepitus who were treated with
either an all-arthroscopic procedure, an all-open procedure, or
a combined procedure in which the bursectomy was completed in an arthroscopic fashion but bone resection was
performed with use of an open approach26. At an average of
three years postoperatively, thirteen of the sixteen patients
were satisfied with the result and had improved function. With
such a limited number of patients, however, it was unclear if
any particular approach was superior to the others. In another
series, twelve patients were followed after they had undergone
a combined arthroscopic bursectomy and mini-open scapular
resection57. At a mean of three years, the pain had decreased
significantly in ten of the twelve patients.
The theoretical advantage of a combined approach is
that arthroscopy provides better visualization and access to the
bursal tissue for a more complete bursectomy and an open
approach provides improved exposure so that the surgeon is
better able to judge and then resect the superomedial or inferomedial angle of the scapula when indicated26. In the literature, the recommended amount of bone resection has
varied26,44,58,63. It is believed that a more appropriate resection of
bone can be performed through an open approach; however,
with an open approach, the muscles must be detached from
the scapula and then reattached through bone tunnels, thus
requiring a more extended postoperative immobilization period and a delay in the initiation of the rehabilitation protocol26,57. In an effort to improve the all-arthroscopic approach,
the authors of a recent cadaver study attempted to identify
landmarks that would allow the entire procedure to be performed arthroscopically, thereby avoiding the need for the
aggressive muscle detachment that is performed with open
techniques. However, this approach has not yet been applied to
clinical practice63, to our knowledge.
Overview
Scapulothoracic crepitus or bursitis, also known as snapping
scapula syndrome, has been recognized for more than a century. However, the entity is often underappreciated and is
probably underdiagnosed. Without a definable skeletal lesion,
most radiographic imaging modalities have been shown to be
of little value in identifying the pathological entity and directing treatment. Thus, although this entity can be associated
with either skeletal or soft-tissue anomalies or lesions, the
diagnosis is generally established on the basis of the clinical
history and physical examination alone. Nonoperative management with anti-inflammatory medications, supervised
physical therapy, and corticosteroid injections is usually successful in alleviating symptoms. Operative intervention can be
considered for patients whose symptoms persist and cause
substantial disability. Open, arthroscopic, and combined techniques have been reported to have successful outcomes. The
literature, however, consists mostly of small case series with
varying operative indications and techniques. Further investigation is needed to clearly establish optimal treatment options for this complex condition. n
Meredith A. Lazar, MD
Young W. Kwon, MD, PhD
Andrew S. Rokito, MD
Department of Orthopedics,
New York University Hospital for Joint Diseases,
301 East 17th Street, 14th Floor, New York, NY 10003.
E-mail address for M.A. Lazar: [email protected]
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