lazar et al jbjs 2009

8/12/2019 Lazar Et Al JBJS 2009

1/13

The PDF of the article you requested follows this cover page.

This is an enhanced PDF from The Journal of Bone and Joint Surgery

2009;91:2251-2262. doi:10.2106/JBJS.H.01347J Bone Joint Surg Am.Meredith A. Lazar, Young W. Kwon and Andrew S. Rokito

Snapping Scapula Syndrome

This information is current as of April 5, 2010

TranslationFREE Spanish http://www.ejbjs.org/cgi/content/full/91/9/2251/DC1

Reprints and Permissions

Permissions] link.and click on the [Reprints andjbjs.orgarticle, or locate the article citation on

to use material from thisorder reprints or request permissionClick here to

Publisher Information

www.jbjs.org20 Pickering Street, Needham, MA 02492-3157The Journal of Bone and Joint Surgery
http://www.ejbjs.org/cgi/content/full/91/9/2251/DC1http://www.ejbjs.org/cgi/content/full/91/9/2251/DC1http://www.jbjs.org/http://www2.ejbjs.org/misc/reprints_perms.dtlhttp://www.jbjs.org/http://www2.ejbjs.org/misc/reprints_perms.dtlhttp://www.jbjs.org/http://www.jbjs.org/http://www.jbjs.org/http://www.jbjs.org/http://www.jbjs.org/http://www2.ejbjs.org/misc/reprints_perms.dtlhttp://www.ejbjs.org/cgi/content/full/91/9/2251/DC1


2/13

CurrentConceptsReview

Snapping Scapula SyndromeBy Meredith A. Lazar, MD, Young W. Kwon, MD, PhD, and Andrew S. Rokito, MD

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.

Nonoperative measures consisting of supervised physical therapy, anti-inflammatory medications, and thera-

peutic injections are the mainstay of treatment.

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 asscapulothoracic crep-itus or bursitis, was first described in 1867 by Boinet1. The severityof the sounds associated with this syndrome were stratified byMauclaire in 1904 as froissement (rustling), frottement (rub-bing), or craquement (cracking), the latter of which was used todenote a sound so loud it must be pathological2. The sound isproduced by a tactile-acoustic phenomenon occurring as a con-sequence of an anomalous tissue between the thoracic wall andthe scapula. While most patients deem these sounds as a peculiarirregularity that does not produce symptoms, some report a clear

correlation between the sounds and pain3

. With an increasingknowledge base and advancing surgical technology, the availabletreatment modalities for such patients are continuing to evolve.This review will discuss the current approach to the diagnosisand 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 theposterior surface of the thoracic cage between the second andseventh ribs. It has two surfaces (ventral and dorsal), three bor-ders (superior, axillary, and vertebral), and three angles (super-omedial, inferomedial, and lateral)4. The scapula, in its staticresting position, lies approximately 5 cm lateral to the spine on

the posterior aspect of the thorax, is angled 30

to40

in relationto the coronal plane, and is tipped anteriorly 10 to 20 withrespect to the sagittal plane5. The scapula is part of the superiorshoulder suspensory complex, which provides attachments tothe axial skeleton. Its only skeletal connections are the acromi-

oclavicular and coracoclavicular ligaments. Consequently, thescapula relies primarily on the surrounding muscles for supportand stability. The contour of the scapula may vary, and, in oneanatomic study, abnormalities were consistently found at thesuperomedial and inferior poles of the scapula6.

The articulation between the scapula and the thoraciccage is one of the most incongruent in the human body. Thescapulothoracic pseudojoint has three layers: superficial, in-termediate, and deep7. Each layer consists of muscles andbursae. The superficial layer comprises the trapezius and la-

tissimus dorsi muscles (Fig. 1). This layer can be associatedwith a well-circumscribed inferior angle bursa, measuring 1.92.4 cm on the average, located between the inferomedial angleof the scapula and the superficial fibers of the latissimus dorsimuscle7. The intermediate layer consists of the rhomboidmajor, rhomboid minor, and levator scapulae muscles. Thetrapezial bursa lies between the trapezius muscle and the baseof the scapular spine and averages 4.3 2.7 cm in size. Thisbursa is particularly important as it provides a smooth surfaceover which the scapula rotates.

In the intermediate layer, along with the trapezial bursa,is the spinal accessory nerve, which crosses the superior borderof the scapula approximately 2.7 cm lateral to its superomedial

angle as it enters the interval between the superomedial angleand the trapezius muscle just lateral to the levator scapulaemuscle7. The dorsal scapular nerve is also in this vicinity as itenters the scapulothoracic region and travels deep to orthrough 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.

2251

COPYRIGHT 2009 BY T HE J OURNAL OF B ONE AND J OINT S URGERY, INCORPORATED

J Bone Joint Surg Am.2009;91:2251-62 d doi:10.2106/JBJS.H.01347


3/13

the scapula before innervating the rhomboid muscles8. Thetransverse cervical artery is divided by the levator scapulaemuscle into the dorsal scapular artery and a branch that runswith the spinal accessory nerve9. The suprascapular nerve isalso in proximity as it travels obliquely across the superomedialangle and superior border of the scapula and courses towardthe suprascapular notch10. These structures are all at risk dur-ing operative treatment of scapulothoracic bursitis and mustbe carefully avoided during dissection9.

The deep layer consists of the serratus anterior and sub-scapularis 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 thethoracic cage and averages 9 7.4 cm in size. The subscapu-laris, or infraserratus, bursa is located between the serratusanterior and subscapularis muscles, is inconsistently present,and averages 5.3 5.3 cm7.

The scapula playsa crucial role in the function of the upperextremity by providing a stable basefor glenohumeral motion. Inaddition, the scapula glides against the thoracic wall to augmentshoulder motion. Scapular motion is required to maintain op-timal muscle length-tension relationships and alignment of theglenohumeral joint during elevation of the upper extremity11.

Biomechanical analyses of normal scapular motion have re-vealed that the scapula can simultaneously rotate and translatealong three axes to support glenohumeral motion12. The ratio ofglenohumeral to scapulothoracic movement (GH/ST ratio) invarious planes has been extensively studied and has been shownto be approximately 2:1 in both forward flexion and abduction.However, among the various planes, the GH/ST ratio has beenfound to vary in a nonlinear fashion depending on the positionof the arm relative to the scapula. Several studies have shown theGH/STratio to range from 1.25 to 3.2, with the ratio in forwardflexion being slightly higher on average than the ratio in ab-

duction11,13,14. Specific rehabilitation protocols for stretching andstrengthening the pectoral muscles, scapular retractors and el-evators, and glenohumeral abductors and external rotators canincrease the GH/ST ratio, which promotes scapular stability andimproves glenohumeral motion15.

Pathophysiology of Scapulothoracic Bursitis

Scapulothoracic bursitis may occur following a single traumaticinsult or as a result of a series of repetitive motions of the scap-ulothoracic joint16-18. In most cases, the bursitis is believed to becaused by abnormal motion between the anterior surface of thescapula and the thoracic cage. In 1933, Milch and Burman re-

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.

2252

T H E J O U R N A L O F B O N E & J O I N T S U R G E R Y d J B J S . O RGVO L U M E 9 1 - A d NU M B E R 9 d S E P T E M B E R 2 0 0 9

S N A P P I N G S C A P U L A S Y N D R O M E


4/13

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.

2253




5/13

ported on a small series of patients with scapulothoracic bursitisand suggested that the pain was caused by an abnormal forwardcurvature of the superomedial angle of the scapula due to var-ious skeletal or soft-tissue abnormalities19.

Scapulothoracic crepitus may be produced by an unusualshape of the scapula19. In a cadaver study, bending of >35wasnoted in 8.6% (sixty) of 700 specimens6. Approximately 6% ofscapulae demonstrate a hook-shaped prominence, known astheLuschka tubercle,at their superomedial angle6. This tuberclemay enlarge and articulate with the thoracic cage, resulting inpainful crepitus6. However, a clear causal relationship betweenthis morphology and the presence of scapulothoracic bursitishas not been demonstrated.

Osteochondroma is themost prevalentbenign tumor of thescapula and has been implicated as a common cause of snappingscapula syndrome20-22. An extensive review of the literatureidentified eighty-nine cases of snapping scapula syndrome, withosteochondroma being the cause in 16% (fourteen)21. Other, less

common, skeletal causes of scapulothoracic crepitus includeskeletal exostoses and other osseous tumors, especially if theyarise from the ventral surface of the scapula, and fracturemalunion of either the ribs or the scapula23,24. The scapula isthe second most frequent location of chondrosarcoma, whichmust be considered in the differential diagnosis of lesions inthe scapulothoracic space25.

Scapulothoracic bursitis may also occur following loss ofdynamic control of scapular motion26. Abnormal scapularmotion can be caused by muscle overuse, muscle imbalancefollowing nerve injury, or pathological conditions of the gle-nohumeral joint27. Scapular dyskinesis has been observed inpatients with known glenohumeral joint pathology and in

specific series has been reported of fourteen of twenty-twopatients with shoulder instability28, seven of seven patientswith impingement28, and fifteen of fifteen patients with rotatorcuff abnormalities29,30. Muscle atrophy secondary to nerveinjury, trauma, or prior operative treatment can lead to di-minished soft-tissue interposition between the scapula and thethoracic 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 anabnormally curved shape and dig into the chest wall31. Thesuperomedial angle of the scapula then impinges along the chestwall during scapulothoracic motion and creates inflammationin the scapulothoracic space. Atrophy of the serratus anterior

following injury to the long thoracic nerve as well as subscap-ularis atrophy in patients with thoracic outlet syndrome havealso been implicated as etiologies of scapulothoracic crepitus32.

Normal scapular motion along the thoracic cage isparticularly important to athletes, and a history of overuseduring activities such as swimming, pitching, weight training,gymnastics, and football has been implicated in the onset ofsymptoms5,33.

A phenomenon described in pitchers known as SICK(scapular malposition, inferior medial border prominence,coracoid pain and malposition, and dyskinesis of scapularmovement) has recently been recognized as an overuse mus-

cular fatigue syndrome that has many of the same features asscapulothoracic bursitis34.

Other causes of scapulothoracic bursitis include prioroperative treatment that violated the periscapular muscula-ture32. For example, in one series, snapping scapula syndromedeveloped in fifteen of 100 patients in whom thoracic outletsyndrome had been treated with resection of the first rib32. Wehave observed scapulothoracic bursitis in women who haveundergone cosmetic breast procedures that involved sub-serratus exploration with implant placement.

Clinical Presentation

HistoryPatients with snapping scapula syndrome who seek medicaltreatment primarily report activity-related pain and crepitus.These symptoms may have an insidious onset, occur after achange in activity pattern, or be associated with trauma21. Theclinician should identify possible precipitating factors and

question the patient regarding the duration and severity of thesymptoms. In addition, symptoms such as shoulder girdle orneck pain and weakness should be documented. Other rele-vant elements of the history include hand dominance, occu-pation, and activity level, which may help to reveal causativefactors. Crepitus associated with a soft-tissue lesion or muscleimbalance is typically softer than that associated with a skeletallesion35. In addition, skeletal lesions may initially present withsubtle findings such as a painless, enlarging mass that does notcause crepitus and that can be misdiagnosed as scapulothoracicbursitis36,37. In the absence of an identifiable lesion, the clini-cian must inquire about the frequency, level, and character ofsports activities because those who engage in repetitive throwing,

swimming, gymnastics, or weight-lifting are particularly sus-ceptible to the development of scapular dyskinesis or bursitis34.

Physical ExaminationThespinemust first be inspectedfor any excessive curvature as thiswill create an abnormal contour about the thoracic cage, which inturn will directly alter scapular motion30. In one series, six of ninepatients diagnosed with snapping scapula syndrome demon-strated kyphosis of the upper thoracic spine with no history ofScheuermann adolescent kyphoscoliosis38. Other postural con-ditions that have been associated with scapulothoracic dysfunc-tion include a forward-tilted head, rounded shoulders, abductedand forward-tipped scapulae, and suboccipital extension. Pa-

tients should also be assessed for sources of referred pain,including cervical radiculopathy, neurological injuries, andpathological changes in the glenohumeral joint39.

The shoulder girdle should then be inspected for anyscapular asymmetry. This can be subtle and its identificationcan require careful assessment. In the presence of scapulardysfunction resulting from a nerve injury, patients have diffi-culty abducting the arm and may compensate by shifting theentire trunk in order to perform tasks that require arm ab-duction25. The position of the scapula should be documentedduring both ascending and descending shoulder motions aswell as during scapular protraction, retraction, and rotation34.

2254




6/13

Palpation of the periscapular region may reveal focaltenderness at the medial scapular border over the super-omedial and/or inferomedial bursae. Adduction and internalrotation of the shoulder allow these borders to be accessed foreasier palpation5. Patients often know how to reproduce thesnapping by elevating and depressing the shoulder, and whenthey do so the crepitus can be localized from the undersurfaceof the scapula25. The active and passive ranges of motion of theshoulder should be carefully examined for any limitations.

The strength of the scapular musculature, specifically the

trapezius, rhomboids, levator scapulae, serratus anterior, andlatissimus dorsi muscles, should also be assessed30. The tra-pezius muscle strength is evaluated by having the patient shrugthe shoulders against resistance. The rhomboids and levatorscapulae can be tested by having the patient place the hands onthe hips and push the elbows backward against resistance. Theserratus anterior is assessed by having the patient press againsta wall with an outstretched arm while the examiner palpatesthe scapula for winging. The latissimus dorsi is tested withdownward and backward pressure of the arm against resistancewhile the examiner palpates the inferomedial angle of thescapula. However, static manual muscle testing may not besufficiently sensitive to detect subtle weakness in these muscles.

It is thus critically important to characterize the dynamicmotion of the scapula28. Scapular motion can be characterizedby the position of the inferomedial or superomedial angle andby the plane in which it rotatescoronal or sagittal12.

In the presence of a lesion, so-called clunking maybe observed when the arm is abducted from 90 to 18020.Pseudo-winging of the scapula can be observed if a skeletallesion pushes against the thorax to displace the scapula awayfrom the body (Fig. 3)40.

Weakness in the major scapular stabilizers (serratus an-terior, trapezius, and rhomboid muscles) may present as dif-ferent patterns of scapular winging. An injury of the long

thoracic nerve causing atrophy of the serratus anterior resultsin lateral scapular winging. Injury to the spinal accessory nervethat results in trapezius atrophy may cause the shoulder todroop or rotate forward more medially and is often more subtlethan the winging associated with dysfunction of the serratusanterior. Scapular winging becomes more evident with motionand stress testing. To evaluate for scapular winging, the exam-iner should observe the scapula and palpate the inferomedialangle during elevation. The scapula should also be observedwhile the patient pushes against a wall or performs a push-up,as these maneuvers accentuate the asymmetric movement ofthe scapula25. If a neurological injury is suspected, electrodi-agnostic studies (electromyography and/or measurement ofnerve conduction velocities) can be performed to determinewhether the results correlate with those of the clinicalexamination41.

Posterior capsular tightness may also be present, espe-cially in throwing athletes. Evaluating external and internal

rotation of both shoulders with the humerus at 90 in thecoronal plane is useful to assess capsular tightness42. The uppertrapezius and the pectoralis minor are other common sites ofmyofascial tightness. Hypertonia in athletes with shoulder paincan also contribute to scapular dyskinesis43.

ImagingImaging modalities used in the evaluation of snapping scapulasyndrome include plain radiographs, computed tomography,magnetic resonance imaging, and ultrasonography. Standardradiographs of the scapula include a true anteroposterior view(with the scapula lying flat against the cassette or the beam tiltedto account for the scapular angle), a tangential transscapular (or

Y) view (with the beam pointed in line with the spine of thescapula), andan axillary lateral view(to assessthe glenohumeraljoint). These projections help identify skeletal irregularitiessuch as osteochondromas, a Luschka tubercle, rib abnormali-ties, or alterations at the superomedial or inferomedial angle ofthe scapula (Fig. 4)6. Lesions that arise from the ventral surfaceof the scapula are particularly apparent in the scapulothoracicspace on the Y view, as are sagittal plane deformities at thesuperomedial or inferomedial angle. Unfortunately, theselesions are not always readily visible on radiographs, and flu-oroscopy has been suggested as an adjunctive tool to dynam-ically visualize the grating or snapping of the scapula23. Severalcase reports have documented the utility of cineradiography

to identify skeletal lesions in patients with scapulothoraciccrepitus44.

The efficacy of computed tomography scanning for theroutine evaluation of scapulothoracic crepitus has remainedcontroversial. While a retrospective study did demonstratehigh intraobserver and interobserver agreement with regardto the assessment of computed tomography scans for scapularcrepitus, the interpretations of these scans did not correlatewell with the clinical findings45. Therefore, the authors sug-gested that the routine use of computed tomography was notjustified for patients with the clinical diagnosis of scap-ulothoracic crepitus45. Similarly, a more recent study demon-

Fig. 3

Thispatient withan osteochondroma on the right scapula

demonstrates scapular asymmetry with maximum inter-

nal rotation.

2255




7/13

strated fairly poor correlation between findings on computedtomography scans and clinical symptoms46. The authors of thatstudy also noted that computed tomography scans, especiallythree-dimensional reconstructions, were reliable in detectingabnormalities and incongruities between the scapula and thethoracic cage in multiple planes, suggesting that these imagesmay be important adjuncts to plain radiographs for theplanning of operative treatment of scapulothoracic crepitus.Given these findings, we believe that a computed tomographyscan would be a useful adjunct to plain radiographs if a bone orcartilage lesion is visible and requires further characterizationfor preoperative planning (Fig. 5).

Magnetic resonance imaging is better than computed

tomography scans for identifying and characterizing soft-tissuemasses. Higuchi et al. reported their experience with usingmagnetic resonance imaging to evaluate scapulothoracic bur-sitis and found it to be more useful than computed tomo-graphy scans for assessing fluid-filled bursal tissue as well as fordistinguishing scapulothoracic bursitis from elastofibroma36.They and other authors37 concluded that magnetic resonanceimaging is a valuable tool for assessing these so-called pseu-dotumors in the scapulothoracic bursa.

Ultrasound has also been used to identify and treatscapulothoracic pathology. Specifically, by identifying the bur-sal tissue dynamically, it can be used for image-guided injec-

tion47. Thus far, however, the use of ultrasound for diagnosis ortreatment of scapulothoracic crepitus appears to be infrequentand published data are mostly limited to case reports47,48.

Nonoperative Treatment

The majority of patients with scapulothoracic crepitus or bur-sitis can be managed successfully without operative treatment.An operation is required only for patients who have a clearlyidentifiable osseous or soft-tissue mass. Nonoperative treatmentoptions include physical therapy, anti-inflammatory medica-tions, and corticosteroid injections49.

The goals of rehabilitation for patients with snappingscapula syndrome are improving muscle strength and balance,addressing postural conditions (such as excessive thoracickyphosis), and core strengthening30,34,50. It is believed that poorposture with the head and shoulders tipped forward causes theposterior scapular stabilizers to weaken relative to the anteriorpectoral muscles, which leads to imbalances that may change

the scapular resting position and decrease scapular elevation15.Kibler and McMullen identified three stages of rehabilitationbased on a program in which the shoulder is considered to bepart of a kinetic chain system30. The kinetic chain model de-picts the body as a system of interdependent parts that work ina proximal-to-distal sequence to impart a desired action atthe distal segment. In kinetic chain shoulder rehabilitation, thelower limbs and the trunk are integrated into most of theexercises, which reinforces normal movement patterns fromthe outset43. Arm elevation requires full scapular retraction,which is incumbent on spine and hip extension to accom-modate scapular motion. Therefore, shoulder function isdependent on thoracic spinal control, which must be rees-

tablished with physical therapy prior to strengthening indi-vidual 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.

Fig. 4

Tangential radiograph of a scapular

osteochondroma (arrow), demon-

strating how these lesions may en-

croach on the scapulothoracic

space and cause bursitis.

2256




8/13

facilitated through contraction of the contralateral gluteusmaximus muscles through the thoracolumbar fascia, whichconnects to the latissimus dorsi muscle. Efficient shouldermotion and muscle activation occur in this proximal-todistal sequence, which is the basis for the ten-week rehabil-itation protocol. The program progresses in a stepwisefashion from the acute phase (zero to three weeks), to therecovery phase (three to eight weeks), and finally to themaintenance phase (six to ten weeks) with specific exercisesprescribed at each interval, bearing in mind that function,rather than time, determines a patients overall progress withthis protocol30.

In the acute phase, the goal of rehabilitation is to reducepain. Consequently, those movements and positions associatedwith discomfort are limited. Trunk flexion and rotation exer-cises are performed so that scapular motion can be achievedwithout moving the arm, which may be painful. Patients areinstructed to perform so-called safe co-contractions, in which

the hand is supported so that the gravitational force on the armis eliminated and pain is minimized51. Abnormal scapularmotion has been attributed to excessive activation of the uppertrapezius muscle combined with decreased control of the lowertrapezius and the serratus anterior muscle. To restore musclecontrol and balanced coactivation, exercises that selectivelyrecruit weaker muscles over hyperactive muscles are recom-mended52. Stretching maneuvers are performed in conjunctionwith closed-kinetic-chain exercises, in which the hand is rel-atively fixed (such as in modified push-ups) and which requireless muscle activation than open-chain exercises (dumbbellpress and machine-rowing)30,51.

In the recovery phase of rehabilitation, strengthening is

performed with motion, which is dependent on the proper pos-ture that has already been established in the acute phase. Closed-kinetic-chain exercises are advanced and should be performedin multiple planes and levels of elevation to reproduce scapularmotion in its varied positions. Cools et al. performed an elec-tromyographic study to elucidate which shoulder girdle exercisesselectively activate middle and lower portions of the trapezius andserratus anterior muscles over the upper trapezius muscle torestore balance to the scapulothoracic musculature52. Side-lyingforward flexion, side-lying external rotation, and prone hori-zontal abduction with external rotation all had favorable upper-to-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 thepatient during this recovery phase of rehabilitation. Exercisesare also performed to continue to strengthen the kinetic chain.Core strength endurance training helps to facilitate dynamicpostural control for prolonged periods of time5.

The maintenance phase begins once good scapularcontrol and motion have been achieved. Plyometric (dynamicstretch-shortening) exercises such as tossing a medicine balland open-chain exercises such as the walking lunge with ashoulder dumbbell press are advanced and integrated. Per-formance of strengthening exercises in various planes whileloading the glenohumeral joint is also prescribed30.

Ciullo reported excellent results in sixty-two of seventy-two patients treated with a combination of diathermy, ultra-

sound, and iontophoresis along with periscapular and rotatorcuff muscle strengthening53. In another study, Groh et al. foundgood or excellent results in twenty-two of thirty patients treatedwith periscapular muscle strengthening50.

A corticosteroid and/or local anesthetic can be injectedinto the scapulothoracic bursa for diagnostic and therapeuticpurposes. These injections are best administered with the pa-tient prone and in the so-called chicken-wing position, withthe shoulder extended and internally rotated to elevate themedial border of the scapula (Fig. 7)49. Care must be taken todirect the needle parallel to the chest wall as pneumothorax is apotential complication35. The injection should be directed to-

Fig. 6-A

Fig. 6-B

Fig. 6-c

Figs. 6-A, 6-B, and6-C Exercises that selectively restore trapezial

muscle balance52

. Fig. 6-A Side-lying forward flexion. Fig. 6-B

Side-lying external rotation. Fig. 6-CProne abduction and external

rotation.

2257




9/13

ward the superomedial or inferomedial angle of the scapula,depending on the location of the pain and the point of max-imal tenderness.

Hodler et al. investigated the efficacy and accuracy ofinjections for the treatment of scapulothoracic bursitis54. In astudy of twenty patients who received injections, eighteen re-ported improvement. The injection site was sterilized, and the

skin and needle track were anesthetized with 1% lidocaine. A22 or 25-gauge 9-cm needle was inserted until the pain wastriggered. After location of the bursa under fluoroscopy, li-docaine and contrast medium were injected; this was followedby injection of betamethasone and bupivacaine. The contrastmedium was injected as part of the study protocol to assess theaccuracy of the injection and identify the presence of a truebursal sac. In seven patients, the contrast medium filled asmooth, well-defined bursal sac. In eight patients, the injectionwas placed intramuscularly as demonstrated by diffuse spread-ing of the contrast medium. In the remaining five patients,some of the contrast medium pooled into a well-defined bursaand some spread diffusely. The eighteen successfully treated

patients had a significant improvement in the visual analogpain scores that lasted from six hours to fifteen months. Theauthors concluded that injections are a safe and effective wayto treat scapulothoracic bursitis. In addition, even patientswithout a well-defined bursa may have relief of pain after alocalized injection54. Other authors have reported similar ef-ficacy of corticosteroid injections administered to providetemporary relief prior to surgical treatment16,26,55.

The use of ultrasound-guided injections is currentlyunder investigation. Its perceived advantage is better visuali-zation of the soft tissues, including adhesions, scarring, andbursal collections, to facilitate more accurate injections47. Clear

clinical benefits of this modality have not been demonstrated,however.

Operative Treatment

IndicationsOperative management may be considered for patients whohave undergone a prolonged course of nonoperative treatmentwithlittle or no improvement16,56-60. Ideally, these patients shouldbe able to localize the pain to the superomedial or inferomedialangle of the scapula. The operative outcome is more reliable ifthe diagnosis can be confirmed with a preoperative injection oflocal anesthetic5,55,58. Lehtinen et al. suggested that failure toreceive at least temporary relief from an injection should bea relative contraindication to operative management26. Otherrelative predictors of a poor operative outcome include theability to voluntarily produce the snapping sound from thescapula, involvement in a Workers Compensation claim orlitigation, and documented nerve deficits5.

Open Techniques and ResultsTo our knowledge, the first report of operative treatment forsnapping scapula was published in 19503. The procedure wasperformed with the use of local anesthesia in three patientswho were asked to move the shoulder during the operationin order to identify the portion of the scapula responsiblefor the symptoms so that it could be resected. Subsequentstudies have shown good outcomes following open partialscapular resection, usually for treatment of a distinct osseousabnormality21,23,44,55,59,61.

The procedure is typically performed with the patient ineither the prone or the lateral decubitus position with the in-

volved extremity draped free. With internal rotation of theshoulder, the medial border of the scapula can be lifted awayfrom the thoracic cavity. The location of the skin incision isvertical, is in line with the medial border of the scapula, and iscentered either superiorly or inferiorly depending on the site ofthe primary pathological findings. For operative dissection ofthe superomedial angle of the scapula (Fig. 8), the trapeziusmuscle may be split in line with its fibers over the scapularspine to expose the underlying structures. During this portionof the procedure, it is imperative to protect the spinal accessorynerve, which crosses the superior border of the scapula justlateral to the superomedial anglei.e., between the super-omedial angle and the trapezius muscle just lateral to the le-

vator scapulae7. The levator scapulae and rhomboid musclescan be released subperiosteally as needed to expose the an-teromedial border of the scapula. Care must be taken when therhomboids are detached to avoid injury to the dorsal scapularnerve, which is approximately 2 cm medial to the medialscapular edge26. Finally, the involved osseous anomaly and/orthe inflamed bursae can be isolated and resected. With thisapproach, the rhomboids are detached subperiosteally in orderto preserve the short Sharpey fibers of the tendinous inser-tions, which may be reattached through drill holes to theirappropriate position55. Although postoperative regimens mayvary, most authors have recommended a period of immobili-

Fig. 7

The so-called chicken-wing position elevates and defines the potential

space for injection at the superior or inferior (arrow) bursa.

2258




10/13

zation in a sling for up to four weeks to allow the muscles toheal 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 ofpatients18,33,56,62. McCluskey and Bigliani treated nine patientswith refractory scapulothoracic bursitis at the supraserratusbursa with isolated open bursectomy56. Fibrotic bursal tissuebetween the serratus anterior muscle and the thoracic cavitywas excised. They reported six excellent and two good results.The remaining patient experienced a spinal accessory nervedeficit that required a tendon transfer, and only a fair outcomewas achieved.

More recently, Nicholson and Duckworth reported onseventeen patients in whom scapulothoracic pain had been

treated with an open operative technique55. All of their patientshad a satisfactory outcome after an average duration of follow-up of 2.5 years. In addition to removal of bursal tissue, thesuperomedial angle of the scapula was resected in five patients.The authors noted that open osseous resection was able toaddress other abnormalities about the area as well as provideeasy access to the trapezial bursa55. In this and other series inwhich removal of a portion of the superomedial angle wasreported, gross and histological examination showed the re-sected 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 fourprofessional baseball pitchers, Sisto and Jobe performed an

open bursectomy at the inferior angle of the scapula33. Histo-logical evaluation of the resected tissue revealed evidence ofchronic inflammation. All patients experienced complete ornearly complete relief of symptoms and were able to return tobaseball at their previous level of competition.

Arthroscopic Techniques and ResultsAlthough technically demanding, arthroscopic surgery forsnapping scapula syndrome offers several theoretical advan-tages over open operative treatment. These include minimizingdissection and preserving muscle attachments, thereby elimi-nating the need for postoperative immobilization and poten-tially shortening the rehabilitation period58. Other advantages

include an improved cosmetic appearance and potentiallydecreased hospital stays.

The patient is usually positioned prone with the armextended and internally rotated to accentuate the medialborder of the scapula49. Some authors have recommended thelateral decubitus position as it allows concurrent evaluation ofthe glenohumeral joint10. Once the patient is positioned, theosseous landmarks are marked on the skin in anticipation ofportal placement (Fig. 9).

All standard portals should be established at least 3 cmmedial to the medial border of the scapula to avoid injuring thedorsal scapular nerve and vessels. Along the vertical axis, the

Fig. 8

Technique for open resection of the superomedial angle of the scapula. a: A

longitudinal incision is madealong the medial scapular edge, and subcutaneousundermining exposes the trapezius muscle, which is split and elevated in line

with itsfibers over the medial aspect of the scapula. b: The rhomboidand levator

muscles are detached from the medial and superior edge to expose the su-

peromedial 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.)

2259




11/13

superior visualization portal should be placed just inferior tothe scapular spine to allow access to both the superomedial andthe inferomedial angle of the scapula. Under arthroscopic vi-sualization, the inferior working portal is then created midwaybetween the scapular spine and the inferomedial scapular an-gle. The instruments should point away from the coracoidprocess to prevent damage to the suprascapular nerve andvessels, which travel just medial to the base of the coracoid9.The visualization and working portals may be interchanged asneeded intraoperatively for improved access to the bursal tis-sues. Portals placed superior to the scapular spine may result ininjury 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 createdsuperiorly and laterally. With use of a so-called inside-outtechnique, this superolateral portal can be located along thesuperior border of the scapula at a distance that is one-third ofthe distance between the superomedial angle and the acro-mion. Cadaver dissection and clinical outcome studies havedemonstrated that this portal can be established without ex-cessive risk to the suprascapular nerve and vessels10,17.

During the bursectomy, it is important to maintain aproper orientation relative to the thoracic cavity and clearly

identify the soft-tissue structures prior to debridement49. Insome patients, the bursal tissue is easily identifiable while, inothers, the tissue appears to be thickened or fibrotic (Fig. 10).An advantage to arthroscopic debridement is that the perios-teal sleeve of the rhomboid attachment is maintained, whichavoids the need for muscle reattachment and thus eliminatesthe necessity for postoperative immobilization26.

After the bursectomy is completed, the arm may bemoved under direct visualization by the surgeon and if thesuperomedial angle is deemed prominent a partial scapularresection can be performed. If there is no prominence, thescapulothoracic space may be temporarily deflated by removingall of the arthroscopy fluid. An examination may then be per-formed with the patient under anesthesia to determine if thesuperomedial angle of the scapula impinges on deeper struc-tures16. If there is osseous impingement, the scapula can thenbe skeletonized with a radiofrequency tissue ablator, and thesuperomedial angle can be resected with use of a high-speed

burr. Although the exact extent of bone resection has beendebated, most authors have recommended removing 2 to 3 cmof bone from the superomedial corner of the scapula26,44,63.Before the procedure is completed, the scapulothoracic jointshould be examined with the patient under anesthesia to en-sure that no impinging structures remain.

Most reports on the outcomes of arthroscopic surgeryfor scapulothoracic bursitis and crepitus are small case serieswith short-term follow-up. In general, however, good-to-excellent results have been reported in the majority of patients.Failures have been attributed mostly to poor patient selectionand technical difficulties16,17,53,58.

In a recent longer-term follow-up study, thirteen pa-

tients underwent arthroscopic scapulothoracic bursectomywith or without bone resection of the superomedial angle16. Ata mean of 6.8 years following surgery, all patients still reported

Fig. 9

Arthroscopic landmarks and portal placement. The superior vi-

sualization 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 in-

feromedial angle.

Fig. 10

Intraoperative photograph showing arthroscopic debridement of the

scapulothoracic bursa. The inflamed bursal tissue is removed from the

scapula and debrided from the subscapularis muscle.

2260




12/13

some degree of scapulothoracic crepitus. Nine of the thirteenpatients, however, reported less pain and improved function.The authors, therefore, suggested that residual scapulothoraciccrepitus does not preclude a satisfactory outcome. In addition,they emphasized the importance of patient selection as theirfour patients with a failure included those with a history ofdrug abuse, C7 radiculopathy with clear scapular winging, andsevere thoracic scoliosis16.

Combined Techniques and ResultsAlthough the specific indications are still unclear, a combinedarthroscopic and open approach may be appropriate for somepatients. Bursectomy allows debridement of all inflamed tissuethat may be the source of pain, and partial scapular resection(when indicated on the basis of the intraoperative examina-tion) relieves the osseous impingement that contributes to thebursitis. Lehtinen et al. reported on sixteen patients withscapulothoracic bursitis and crepitus who were treated with

either an all-arthroscopic procedure, an all-open procedure, ora combined procedure in which the bursectomy was com-pleted in an arthroscopic fashion but bone resection wasperformed with use of an open approach26. At an average ofthree years postoperatively, thirteen of the sixteen patientswere satisfied with the result and had improved function. Withsuch a limited number of patients, however, it was unclear ifany particular approach was superior to the others. In anotherseries, twelve patients were followed after they had undergonea combined arthroscopic bursectomy and mini-open scapularresection57. At a mean of three years, the pain had decreasedsignificantly in ten of the twelve patients.

The theoretical advantage of a combined approach is

that arthroscopy provides better visualization and access to thebursal tissue for a more complete bursectomy and an openapproach provides improved exposure so that the surgeon isbetter able to judge and then resect the superomedial or in-feromedial angle of the scapula when indicated26. In the lit-erature, the recommended amount of bone resection hasvaried26,44,58,63. It is believed that a more appropriate resection ofbone can be performed through an open approach; however,with an open approach, the muscles must be detached fromthe scapula and then reattached through bone tunnels, thus

requiring a more extended postoperative immobilization pe-riod and a delay in the initiation of the rehabilitation proto-col26,57. In an effort to improve the all-arthroscopic approach,the authors of a recent cadaver study attempted to identifylandmarks that would allow the entire procedure to be per-formed arthroscopically, thereby avoiding the need for theaggressive muscle detachment that is performed with opentechniques. However, this approach has not yet been applied toclinical practice63, to our knowledge.

Overview

Scapulothoracic crepitus or bursitis, also known as snappingscapula syndrome, has been recognized for more than a cen-tury. However, the entity is often underappreciated and isprobably underdiagnosed. Without a definable skeletal lesion,most radiographic imaging modalities have been shown to beof little value in identifying the pathological entity and di-recting treatment. Thus, although this entity can be associated

with either skeletal or soft-tissue anomalies or lesions, thediagnosis is generally established on the basis of the clinicalhistory and physical examination alone. Nonoperative man-agement with anti-inflammatory medications, supervisedphysical therapy, and corticosteroid injections is usually suc-cessful in alleviating symptoms. Operative intervention can beconsidered for patients whose symptoms persist and causesubstantial disability. Open, arthroscopic, and combined tech-niques have been reported to have successful outcomes. Theliterature, however, consists mostly of small case series withvarying operative indications and techniques. Further inves-tigation is needed to clearly establish optimal treatment op-tions for this complex condition. n

Meredith A. Lazar, MDYoung W. Kwon, MD, PhDAndrew S. Rokito, MDDepartment 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]

References

1. Boinet. Fait clinique. Bull Mem Sec Chir Paris. 1867;8:458.

2. Mauclaire. Craquements sous-capsulaires pathologiques traites parlinterposition musculaire interscapulo-thoracique. Bull Mem Soc Chir Paris.1904;30:164-8.

3. Milch H. Partial scapulectomy for snapping of the scapula. J Bone Joint SurgAm. 1950;32:561-6.

4. Gray H. Anatomy of the human body. Lewis WH, editor. 20th ed. New York:Bartleby.com; 2000.

5. Manske RC, Reiman MP, Stovak ML. Nonoperative and operative managementof snapping scapula. Am J Sports Med. 2004;32:1554-65.

6. Edelson JG. Variations in the anatomy of the scapula with reference to thesnapping scapula. Clin Orthop Relat Res. 1996;322:111-5.

7. Williams GR Jr, Shakil M, Klimkiewicz J, Iannotti JP. Anatomy of the scap-ulothoracic articulation. Clin Orthop Relat Res. 1999;359:237-46.

8. Frank DK, Wenk E, Stern JC, Gottlieb RD, Moscatello AL. A cadaveric study ofthe motor nerves to the levator scapulae muscle. Otolaryngol Head Neck Surg.1997;117:671-80.

9. Ruland LJ 3rd, Ruland CM, Matthews LS. Scapulothoracic anatomy for the ar-throscopist. Arthroscopy. 1995;11:52-6.

10. Chan BK, Chakrabarti AJ, Bell SN. An alternative portal for scapulothoracicarthroscopy. J Shoulder Elbow Surg. 2002;11:235-8.

11. McClure PW, Michener LA, Sennett BJ, Karduna AR. Direct 3-dimensionalmeasurement of scapular kinematics during dynamic movements in vivo.J Shoulder Elbow Surg. 2001;10:269-77.

2261




13/13

12. Kibler WB, Uhl TL, Maddux JW, Brooks PV, Zeller B, McMullen J. Qualitativeclinical evaluation of scapular dysfunction: a reliability study. J Shoulder ElbowSurg. 2002;11:550-6.

13. Ludewig PM, Cook TM, Nawoczenski DA. Three-dimensional scapular orien-tation and muscle activity at selected positions of humeral elevation. J OrthopSports Phys Ther. 1996;24:57-65.

14. Poppen NK, Walker PS. Normal and abnormal motion of the shoulder. J BoneJoint Surg Am. 1976;58:195-201.

15. Wang CH, McClure P, Pratt NE, Nobilini R. Stretching and strengtheningexercises: their effect on three-dimensional scapular kinematics. Arch Phys MedRehabil. 1999;80:923-9.

16. Pearse EO, Bruguera J, Massoud SN, Sforza G, Copeland SA, Levy O.Arthroscopic management of the painful snapping scapula. Arthroscopy. 2006;22:755-61.

17. Pavlik A, Ang K, Coghlan J, Bell S. Arthroscopic treatment of painful snappingof the scapula by using a new superior portal. Arthroscopy. 2003;19:608-12.

18. Richards RR, McKee MD. Treatment of painful scapulothoracic crepitus byresection of the superomedial angle of the scapula. A report of three cases. ClinOrthop Relat Res. 1989;247:111-6.

19. Milch H, Burman MS. Snapping scapula and humerus varus. Report of sixcases. Arch Surg. 1933;26:570-88.

20. Fukunaga S, Futani H, Yoshiya S. Endoscopically assisted resection of ascapular osteochondroma causing snapping scapula syndrome. World J SurgOncol. 2007;5:37.

21. Carlson HL, Haig AJ, Stewart DC. Snapping scapula syndrome: three casereports and an analysis of the literature. Arch Phys Med Rehabil. 1997;78:506-11.

22. van Riet RP, Van Glabbeek F. Arthroscopic resection of a symptomatic snap-ping subscapular osteochondroma. Acta Orthop Belg. 2007;73:252-4.

23. Parsons TA. The snapping scapula and subscapular exostoses. J Bone JointSurg Br. 1973;55:345-9.

24. Takahara K, Uchiyama S, Nakagawa H, Kamimura M, Ohashi M, Miyasaka T.Snapping scapula syndrome due to malunion of rib fractures: a case report.J Shoulder Elbow Surg. 2004;13:95-8.

25. Rockwood CA Jr, Matsen FA III, Wirth MA, Lippitt SB. The shoulder. 3rd ed.Philadelphia: Saunders; 2004.

26. Lehtinen JT, Macy JC, Cassinelli E, Warner JJ. The painful scapulothoracicarticulation: surgical management. Clin Orthop Relat Res. 2004;423:99-105.

27. Strizak AM, Cowen MH. The snapping scapula syndrome. A case report. J BoneJoint Surg Am. 1982;64:941-2.

28. Warner JJ, Micheli LJ, Arslanian LE, Kennedy J, Kennedy R. Scapulothoracicmotion in normal shoulders and shoulders with glenohumeral instability and im-pingement syndrome. A study using Moire topographic analysis. Clin Orthop RelatRes. 1992;285:191-9.

29. Paletta GA Jr, Warner JJ, Warren RF, Deutsch A, Altchek DW. Shoulder kine-matics with two-plane x-ray evaluation in patients with anterior instability or rotatorcuff tearing. J Shoulder Elbow Surg. 1997;6:516-27.

30. Kibler WB, McMullen J. Scapular dyskinesis and its relation to shoulder pain.J Am Acad Orthop Surg. 2003;11:142-51.

31. Matsen FA 3rd, Lippitt SB, Sidles JA, Harryman DT 2nd. Practical evaluationand management of the shoulder. Philadelphia: WB Saunders; 1994.

32. Wood VE, Verska JM. The snapping scapula in association with the thoracicoutlet syndrome. Arch Surg. 1989;124:1335-7.

33. Sisto DJ, Jobe FW. The operative treatment of scapulothoracic bursitis inprofessional pitchers. Am J Sports Med. 1986;14:192-4.

34. Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrumof pathology Part III: The SICK scapula, scapular dyskinesis, the kinetic chain, andrehabilitation. Arthroscopy. 2003;19:641-61.

35. Kuhn JE, Plancher KD, Hawkins RJ. Symptomatic scapulothoracic crepitus andbursitis. J Am Acad Orthop Surg. 1998;6:267-73.

36. Higuchi T, Ogose A, Hotta T, Okamoto K, Kamura T, Sasai K, Hatano H,Morita T. Clinical and imaging features of distended scapulothoracic bursitis:spontaneously regressed pseudotumoral lesion. J Comput Assist Tomogr.2004;28:223-8.

37. Ken O, Hatori M, Kokubun S. The MRI features and treatment of scap-ulothoracic bursitis: report of four cases. Ups J Med Sci. 2004;109:57-64.

38. Cobey MC. The rolling scapula. Clin Orthop Relat Res. 1968;60:193-4.

39. Neer CS. Shoulder reconstruction. Philadelphia: WB Saunders; 1990.

40. Andrews JR, Wilk KE. The athletes shoulder. New York: Churchill Livingstone;

1994.41. Lehtinen JT, Tetreault P, Warner JJ. Arthroscopic management of painful andstiff scapulothoracic articulation. Arthroscopy. 2003;19:E28.

42. Tyler TF, Nicholas SJ, Roy T, Gleim GW. Quantification of posterior capsuletightness and motion loss in patients with shoulder impingement. Am J SportsMed. 2000;28:668-73.

43. McMullen J, Uhl TL. A kinetic chain approach for shoulder rehabilitation.J Athl Train. 2000;35:329-37.

44. Oizumi N, Suenaga N, Minami A. Snapping scapula caused by abnormalangulation of the superior angle of the scapula. J Shoulder Elbow Surg. 2004;13:115-8.

45. de Haart M, van der Linden ES, de Vet HC, Arens H, Snoep G. The value ofcomputed tomography in the diagnosis of grating scapula. Skeletal Radiol.1994;23:357-9.

46. Mozes G, Bickels J, Ovadia D, Dekel S. The use of three-dimensionalcomputed tomography in evaluating snapping scapula syndrome. Orthopedics.

1999;22:1029-33.

47. Saboeiro GR, Sofka CM. Imaging-guided treatment of scapulothoracic bursitis.HSS J. 2007;3:213-5.

48. Huang CC, Ko SF, Ng SH, Lin CC, Huang HY, Yu PC, Lee TY. Scapulothoracicbursitis of the chest wall: sonographic features with pathologic correlation.J Ultrasound Med. 2005;24:1437-40.

49. Millett PJ, Pacheco IH, Gobezie R, Warner JJP. Management of recalcitrantscapulothoracic bursitis: endoscopic scapulothoracic bursectomy and scap-uloplasty. Tech Shoulder Elbow Surg. 2006;7:200-5.

50. Groh GI, Simoni M, AIIen T, Dwyer T, Heckman MM, Rockwood CA Jr. Treat-ment of snapping scapula with a periscapular muscle strengthening program[abstract]. J Shoulder Elbow Surg. 1996;5(2-Pt 2):S6.

51. Kibler WB, Livingston B. Closed-chain rehabilitation for upper and lowerextremities. J Am Acad Orthop Surg. 2001;9:412-21.

52. Cools AM, Geerooms E, Van den Berghe DF, Cambier DC, Witvrouw EE.Isokinetic scapular muscle performance in young elite gymnasts. J Athl Train.2007;42:458-63.

53. Ciullo JV. Subscapular bursitis: treatment of snapping scapula or wash-board syndrome. Arthroscopy. 1992;8:412-3.

54. Hodler J, Gilula LA, Ditsios KT, Yamaguchi K. Fluoroscopically guidedscapulothoracic injections. AJR Am J Roentgenol. 2003;181:1232-4.

55. Nicholson GP, Duckworth MA. Scapulothoracic bursectomy for snappingscapula syndrome. J Shoulder Elbow Surg. 2002;11:80-5.

56. McCluskey GM III, Bigliani LU. Surgical management of refractory scap-ulothoracic bursitis. Orthop Trans. 1991;15:801.

57. Lien SB, Shen PH, Lee CH, Lin LC. The effect of endoscopic bursectomy withmini-open partial scapulectomy on snapping scapula syndrome. J Surg Res.2008;150:236-420.

58. Harper GD, McIlroy S, Bayley JI, Calvert PT. Arthroscopic partial resection ofthe scapula for snapping scapula: a new technique. J Shoulder Elbow Surg.1999;8:53-7.

59. Morse BJ, Ebraheim NA, Jackson WT. Partial scapulectomy for snappingscapula syndrome. Orthop Rev. 1993;22:1141-4.

60. Percy EC, Birbrager D, Pitt MJ. Snapping scapula: a review of the literature andpresentation of 14 patients. Can J Surg. 1988;31:248-50.

61. Cameron HU. Snapping scapulae: a report of three cases. Eur J RheumatolInflamm. 1984;7:66-7.

62. Arntz CT, Matsen FA 3rd. Partial scapulectomy for disabling scapulo-thoracicsnapping. Orthop Trans. 1990;14:252-3.

63. Bell SN, van Riet RP. Safe zone for arthroscopic resection of the superomedialscapular border in the treatment of snapping scapula syndrome. J Shoulder ElbowSurg. 2008;17:647-9.

2262



lazar et al jbjs 2009

Documents