Scapular Positioning in Athlete’s Shoulder...‘scapular dyskinesis’ is an alteration of the...

Sports Med 2008; 38 (5): 369-386REVIEW ARTICLE 0112-1642/08/0005-0369/$48.00/0

© 2008 Adis Data Information BV. All rights reserved.

Scapular Positioning inAthlete’s ShoulderParticularities, Clinical Measurements and Implications

Benedicte Forthomme, Jean-Michel Crielaard and Jean-Louis Croisier

Department of Physical Medicine and Rehabilitation, University of Liege, CHU SartTilman, Belgium

ContentsAbstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3691. Laboratory Measurement of Scapular Kinematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3712. Clinical Measurement of Scapular Kinematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3723. The Scapula in Sports Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374

3.1 Adaptive Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3743.2 Scapulothoracic Muscle Fatigue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3743.3 Pathological Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375

3.3.1 Impingement Syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3763.3.2 Unstable Shoulder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377

3.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3784. Conservative Management of Scapular Malposition – Rehabilitation . . . . . . . . . . . . . . . . . . . . . . . . . . 379

4.1 Flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3794.2 Strengthening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3804.3 Scapular Taping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382

5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383

Despite the essential role played by the scapula in shoulder function, currentAbstractconcepts in shoulder training and treatment regularly neglect its contribution. The‘scapular dyskinesis’ is an alteration of the normal scapular kinematics as part ofscapulohumeral rhythm, which has been shown to be a nonspecific response to ahost of proximal and distal shoulder injuries. The dyskinesis can react in manyways with shoulder motion and function to increase the dysfunction. Thoracickyphosis, acromio-clavicular joint disorders, subacromial or internal impinge-ment, instability or labral pathology can alter scapular kinematics. Indeed, altera-tion of scapular stabilizing muscle activation, inflexibility of the muscles andcapsule-ligamentous complex around the shoulder may affect the resting positionand motion of the scapula. Given the interest in the scapular positioning andpatterns of motion, this article aims to give a detailed overview of the literaturefocusing on the role of the scapula within the shoulder complex through the sportscontext. Such an examination of the role of the scapula requires the description ofthe normal pattern of scapula motion during shoulder movement; this also impliesthe study of possible scapular adaptations with sports practice and scapulardyskinesis concomitant to fatigue, impingement and instability. Different meth-ods of scapular positioning evaluation are gathered from the literature in order tooffer to the therapist the possibility of detecting scapular asymmetries throughclinical examinations. Furthermore, current concepts of rehabilitation dealing

370 Forthomme et al.

with relieving symptoms associated with inflexibility, weakness or activationimbalance of the muscles are described. Repeating clinical assessments through-out the rehabilitation process highlights improvements and allows the therapist toactualize rationally his or her intervention. The return to the field must beaccompanied by a transitory phase, which is conducive to integrating newinstructions during sports gestures. On the basis of the possible scapular distur-bance entailed in sports practice, a preventive approach that could be incorporatedinto training management is encouraged.

The shoulder complex is involved in a great shoulder by improving the concavity-compressioneffect.[1,6,11]many sports and athletic activities requiring specific

gestures.[1-7] Shoulder function represents a focus of The ‘second’ role of the scapula is to provideinterest both for many sports medicine specialists adapted motion along the thoracic wall because theand for trainers. An understanding of shoulder patterns of scapular motion are related to the type ofbiomechanics is of premium importance, even more task being performed. For example, for the shoulderso since athletes who participate in repeated over- involved in physical work, scapular retraction cre-head activities appear to be most specifically at risk ates a stable base for tasks that require reaching,of developing shoulder pain.[2] pushing or pulling.[3,4,10,11,16]

The ‘third’ role of the scapula in shoulder func-The scapula plays an important role in normaltion is the elevation of the acromion to clear theshoulder function.[8-12] In sports in which demandsacromion from the moving rotator cuff, so as toplaced on the shoulder are extremely high, the quali-decrease impingement and coraco-acromialty of movements depends on the interaction betweenarch compression.[6,8,10,13]scapular and glenohumeral kinematics. Abnormal

The ‘fourth’ role of the scapula in shoulder func-scapular kinematics and associated muscle dysfunc-tion is that of being a link in the proximal to distaltion are assumed to contribute to shoulder painsequencing of velocity, energy and forces.[6,8,16] Thepathology.[5,6,13]

largest proportion of kinetic energy and force in theHowever, up until recently, the role of the scapu-‘kinetic chain’ is derived from the larger proximalla in sports gesture, as well as in the clinical evalua-body segments (the legs, back and trunk).[8] Thetion or treatment of shoulder disorders has receivedscapula, providing a stable and controlled platformlittle attention from researchers and clinicians.[5]

regulating the forces, is pivotal and transfers theWith the aim of describing more precisely the strong forces and high energy to the distal body

motion capacity of the shoulder, the kinematic inter- segments: the arm and the hand.[6,8,12,16]

action between the scapula and the humerus was The intricate role of the scapula into the shoulderintroduced by Codman[14] and termed ‘scapulo- movements oblige the therapists to consider thehumeral rhythm’.[14,15]

pattern of motion and position of the scapula in theKibler et al.[8-10] have summarized several roles frame of shoulder dysfunction. Set apart from the

for the scapula function into the shoulder complex scapula’s normal status, ‘scapular dyskinesis’ is de-(figure 1). The ‘primary’ role indicates that the fined as an observable alteration in the position ofscapula moves in coordination with the moving hu- the scapula and the patterns of scapular motion inmerus, so that the instant centre of rotation is con- relation to the thoracic cage.[10,17] Several factorsstrained within a physiological pattern throughout might create these abnormal patterns and this altera-the full range of the shoulder motion.[6,10,11] The tion in position: a resting posture of excessive tho-proper alignment of the glenoid allows optimum racic kyphosis associated with an increased cervicalfunction of both the bony constraints and the mus- lordosis, fractures of the clavicle and acromio-cla-cles of the rotator cuff. The intrinsic muscles of the vicular joint injuries or athrosis can alter scapularrotator cuff provide dynamic stabilization of the kinematics.[10] Likewise, subacromial impinge-

© 2008 Adis Data Information BV. All rights reserved. Sports Med 2008; 38 (5)

Scapular Positioning in Athlete’s Shoulder 371

ment of the shoulder dysfunction with which thepatient presents.

1. Laboratory Measurement ofScapular Kinematics

Laboratory measurements of scapular displace-ments are typically capable of quantifying the scap-ular kinematics 3-dimensionally (3-D).[28,29] Para-meters such as the type of instrumentation (electro-magnetic tracking device,[4,28,29] magneticresonance-based techniques,[21] Moire topogra-phy,[17] reconstruction from radiographic assess-ment,[30,31] fresh frozen cadaver shoulder experi-mentation[1,32]), rotation matrix used, anatomicalbody landmarks, local reference system orientation,specific task requirements and planes of arm eleva-tion (cardinal vs scapular) have differed widelyacross studies according to the goal pur-sued.[10,15,29,31-35] Recently, with the aim to facilitateand encourage communication among researchersor clinicians, the International Society of Biome-chanics is recommending use of the standardizeddescription of scapular motion, anatomicallandmarks, local coordinate axes and Euler anglesequences for angle calculation.[34,36]

The scapula moves simultaneously around thefollowing three axes of motion (figure 2):[28,29,37,38]

Efficiency of sport gesture

Healthyshoulder

Clearance of thesubacromial space

Elevation ofthe acromion

III role

Kinetic chaintransfer

Stablebase

Stability

Concavity-compression

effect

Link fromproximal to distal

IV role

True placementon the thorax

II role

Alignmenthumerus/glenoid

I role

Fig. 1. Four roles of the scapula inspired from Kibler.[8]

ment,[13,18-20] instability,[12,17,21,22] SLAP (SuperiorLabrum, Anterior to Posterior) lesion[23] and internalimpingement[24] are shown to be associated withscapular dyskinesia. Alteration of scapular stabiliz-ing muscle activation or coordination most frequent-ly entails scapular dyskinesis.[13,25] Similarly, inflex-ibility or contracture of the muscles and ligaments orcapsule around the shoulder can affect the restingposition and motion of the scapula.[10,26,27] Themuscle inhibition leading to pain and scapular insta-bility appears to be a nonspecific secondary res-ponse to certain glenohumeral and scapulothoraciccauses.[12] Moreover, to date, no reproducible asso-ciation has been shown between specific shoulderpathological diagnoses and specific dyskinesis pat-terns.[5] Dyskinesis exists in symptomatic patients,in that it alters scapulohumeral rhythm and efficientjoint mechanics; consequently it creates dysfunc-tion. It therefore represents part of the overall treat-

Externalrotation

Internalrotation

Anteriortilting

Posteriortilting

Upward rotation

Downward rotation

Y

Z

X

Fig. 2. Scapula axes (X, Y, Z) and 3-dimensional rotations. Upwardand downward rotations occur around Y, internal and external rota-tions occur around Z and anterior-posterior tilting occurs around X.



• scapular anterior/posterior tipping (or tilting) in proximately linearly throughout humeral elevation,the sagittal plane (thanks to a transversal axis); especially beyond 50° of elevation. Posterior tilting

and external rotation motions were non-linear, with• upward/downward rotation in the frontal planethe majority of these motions occurring after 90° of(corresponding to an antero-posterior axis);arm elevation.[35] In the study by McQuade and• internal/external rotation in the transverse planeSmidt,[15] the scapulohumeral rhythm (describing(thanks to a vertical axis).the change in humeral elevation proportional to theElevation and depression of the scapula corre-change in scapular upward rotation) ratio decreasedsponds to a translatory motion of the scapula on thefrom 7.9 : 1 to 2.1 : 1 as the arm was elevated, duethoracic wall.to a non-linear scapular upward rotation with hu-Comparing data on the pattern of scapula motionmeral elevation.across studies is difficult because of several impor-

McQuade and Smidt[15] studied the effect of ex-tant methodological differences.[35] Based on theternal load on the scapular kinematics; they observ-various studies, the humeral elevation was com-ed that the unloaded (passive) arm scapulohumeralbined with a general pattern of scapular externalrhythm was higher than the light load (active eleva-rotation (or retraction), upward (or lateral) rotationtion against the weight of the limb) or heavy loadedand posterior tilting (or backward) along with cla-(against maximal resistance) arm, but there was novicular elevation and retraction.[34,35,39,40] For exam-statistically significant difference between the lightple, Ludewig et al.[40] measured, in a 3-D analysis, aand heavy resistance loads.[15] During repeated mea-mean scapular motion of 13° of external rotation,surements of scapulohumeral alignment in a popula-34° of upward rotation and 15° of posterior tilt fromtion of healthy volunteers, Price et al.[42] found no0° to 140° of humeral elevation in the scapularsignificant difference in scapula motion during pas-plane.sive and active humeral elevation in the coronalMcClure et al.[35] observed, in a 3-D analysis thatplane, between 10° and 50° of abduction. Theycompared the humeral elevation through the scapu-concluded that passive manipulation treatment maylar and sagittal planes, that the scapular upwardhave an effect through replication of the scapulo-rotation amounted to 50°, on average, in the scapularhumeral alignment, which is adopted during activeplane and 46° in the sagittal plane through the hu-exercise.[42] Ebaugh et al.[43] highlighted the samemeral motion. Meskers et al.[41] found an increasedfindings as Price et al.[42] from the early phase of armscapular upward rotation during the humeral eleva-motion (in the scapular plane). Nevertheless, thetion in the sagittal plane in comparison with thescapular upward rotation increased under the condi-frontal plane. According to those different stud-tion of active arm elevation through the mid-rangeies,[35,41] the scapular plane allows the highest up-(90–120°) of arm elevation due to the activity of theward rotation during humeral elevation.upper, lower trapezius and serratus anterior mus-In the study by Borstad and Ludewig,[38] an elec-cles.[43] For the unloaded (passive) condition, thetromagnetic tracking device described 3-D scapularstudy by McQuade and Smidt[15] reported less up-kinematics during humeral elevation and loweringward rotation already during the first phases of thein the scapular plane. Small, but statistically signif-motion. These discrepancies could be attributable toicant, differences in internal rotation and scapulardifferent methods of passively elevating the armtipping during the eccentric phase (lowering) of armresulting in a different amount of muscle activity.[43]

elevation have been identified at higher humeralangles, while no significant difference for scapular 2. Clinical Measurement ofupward rotation has been found.[38] Internal rotation Scapular Kinematicswas significantly increased in the eccentric phase at100° and scapular anterior tipping was significantly Nevertheless, those laboratory studies useddecreased during the eccentric phase at 80° and 120° equipment or data collection that were not availableangles.[38] to the clinical setting.[9,44,45] Conversely, clinical

McClure et al.[35] found that upward rotation of measures (inclinometer, tape measure) are only ca-the scapular and clavicular rotation occurred ap- pable of measuring scapular kinematics 2-dimen-



sionally (2-D), but can easily be used by the clini- • position 1, the subject’s arm is relaxed at the sidecian. (0° of humeral elevation);

• position 2, the subject places his or her hand onThe inclinometer is capable of measuring anglesthe lateral iliac crest;(in degrees) from a horizontal reference[45] to assess

• position 3 corresponds to an internally rotatedstatic positions of scapular upward rotation. Differ-and abducted arm to 90°.ent authors have demonstrated that these clinical

assessments give valid and accurate information Two measurements are performed using a tape inregarding scapular kinematics.[10,45] Johnson et al.[45] each position (between the inferior angle of thecompared 2-D measurements using an inclinometer scapula and the closest spinous process) in order toand obtained 3-D measurements using a magnetic allow calculation of an average value.[8,9,47,49,50]

tracking device both with the arm fixed and during In one group of injured patients, Kibler et al.[8-10]

arm movement (0°, 60°, 90° and 120° of humeral observed that the degree of asymmetry actually in-elevation in the scapular plane). The digital incli- creased when moving from the first to the thirdnometer showed good to excellent intrarater reliabil- position; therefore, a 1.5-cm asymmetry in any ofity and good to excellent validity when measuring the positions has been established as a threshold forscapular upward rotation during a static position or the identification of an abnormal pattern.humeral elevation in the scapular plane.[45] Watson Kibler et al.[9] studied the reliability and validityet al.[46] established very good intrarater reliability of this measurement concept. Studies on the accura-with a plurimeter gravity inclinometer. They found cy of marking this infero-medial border of the scap-scapular upward rotation ranged between 2.8 ± 6.1° ula in comparison with radiographic evaluation haveat rest and 39.1 ± 8.4° at 120° of humeral eleva- shown a correlation of 0.91 with the different posi-tion.[46] Borsa et al.[44] confirmed the highest upward tions.[8] Test-retest and intertest reliability indicatedrotation in the scapular plane in comparison with the that the test-retest (intratester) relationship was be-sagittal plane using an inclinometer measurement. tween 0.84 and 0.88 and that the intertester reliabili-Despite the fact that inclinometer measurements ty was between 0.77 and 0.85, depending on theconcern only the upward rotation, it can easily be position.[8]

used by clinicians when evaluating the scapular Based on personal findings, Gibson et al.[50] reck-motion. oned that intratester reliability of the Kibler LSST

Linear assessment using tape measures aims to method ranged from good to high, although theevidence the possible scapular asymmetries between intertester reliability was poor. In a 71-subject study,the pathological and healthy sides of a pa- Koslow et al.[52] observed that 52 of the overalltient.[8,9,47-50] Kibler and McMullen[10] described pat- sample displayed a difference of at least 1.5 cm interns of abnormal motion in scapular dyskinesis one or more of the three positions. They concludedbased on simple bilateral visual observation of scap- that the specificity of the LSST test was of 26.8%.[52]

ular position with the patient’s arms at rest at the Odom et al.,[49] comparing a heterogeneous sampleside and during elevation and lowering in the scapu- of control subjects and patients with multiple typesla plane. Even if such an approach remains subjec- of shoulder injury, found that the sensitivity andtive, Kibler et al.[51] showed that, with refinement, specificity of the LSST measurements were poor. Inclinical observation is a qualitative method that al- their opinion, the LSST should not be used to identi-lows clinicians to categorize dynamic scapular dys- fy people with shoulder dysfunction. Nijs et al.[47]

functional patterns. observed coefficients of >0.70 (interobserver relia-bility in intraclass correlation coefficients), but theyQuantitative measurement of scapular position-found no association between the outcome of theing, as proposed by Kibler et al.[8,9] can be achievedtests and the self-reported pain severity or disability.with the lateral test (LSST – lateral scapular side

test), by evaluating scapular symmetry as varying Based on our clinical experience, we believe thatloads are placed on the supporting muscula- the LSST method contributes towards assessingture.[8,9,47,49,50] Three positions of the upper extremi- scapular asymmetry and to quantifying possible im-ties are proposed: provement through the rehabilitation process. De-



spite an apparent lack of specificity regarding the signalled an abducted scapula.[48] The isometricnature of the pathology, the scapular dyskinesis force was assessed using a hand-held dynamometerconcept is regularly integrated into the rehabilitation through specific muscle testing.[48] Diveta et al.[48]

process.[53] found no relationship between isometric muscle per-formance of either the middle trapezius or theMuscular force production and muscular balancepectoralis minor muscles and scapular abductionhave been postulated to be major factors in thepositioning.postural alignment of a healthy population.[48]

Kendall et al.[54] have proposed that muscle weak-3. The Scapula in Sports Activityness would affect postural alignment and that an

imbalance in muscle strength could lead to posturaldeviations. For example, tightness in the pectoralis 3.1 Adaptive Patternsminor or in the short head of the biceps, both of

Downar et al.[55,56] demonstrated, using a digitalwhich are attached to the coracoid process, wouldinclinometer, that professional baseball players ex-create an anterior tilt and forward pull on the scapu-hibited a higher degree of total scapular rotation inla. Kendall et al.[54] used a supine measurement ofthe throwing shoulder. This shift towards upwardthe pectoralis minor muscle. This method quantifiesrotation may be a functional adaptation to ensurethe distance between the treatment table and themaintenance of the subacromial space during over-posterior border of the acromion. Borstad,[37] in ahead throwing.[55,56] Myers et al.[4] studied the scap-comparison of several postural measurements, ques-ular position and orientation during scapular planetioned the validity of measurements for determininghumeral elevation assessed with electromagneticpectoralis minor muscle resting taken with the indi-tracking in a group of 21 throwing athletes and 21vidual positioned supine. For the pectoralis minorcontrol subjects. They showed that, in comparisonmuscle measurement, the author used a validatedwith non-throwing athletes, healthy throwing ath-method: different digitizing landmarks representedletes exhibited significantly increased upward rota-the origin and insertion of the muscle, the electro-tion, combined with a retraction of the scapulamagnetic motion capture system determines the vec-during humeral elevation. Neither differences in an-tor distance between the landmarks and consequent-terior/posterior tipping nor in elevation/depressionly, the pectoralis minor muscle length.[37] In thatwere observed.[4] For these authors, the presence ofstudy, the distance from the sternal notch to thesufficient upward rotation during throwing is vital tocoracoid process showed the highest correlationinjury-free performance by clearing the acromionwith pectoralis minor muscle length.[37] Borstad[37]

from the underlying subacromial structures, thusgave evidence that internal rotation of the scapula atpreventing subacromial impingement.[4]

rest was correlated with pectoralis minor musclelength: an increased scapular internal rotation in a

3.2 Scapulothoracic Muscle Fatiguerelaxed standing position corresponded to a short-ened pectoralis minor muscle. McQuade et al.[57] imposed, in healthy subjects, a

Diveta et al.[48] investigated the relationship be- fatigue-inducing exercise with a pulley mechanismtween the position of the scapula and the force attached to a Cybex II® 1 isokinetic dynamometer,production of the middle trapezius and pectoralis the subjects were instructed to elevate the arm withminor muscles. In that study, the scapular abduction maximal effort as many times possible. They ob-was assessed by dividing the total scapular distance served a decrease in scapulohumeral rhythm (in-from the third thoracic vertebrae to the postero- creased upward rotation in proportion to gle-inferior angle of the acromion by the length of the nohumeral motion) with fatigue.[57] This was a pri-scapula (determined by placing the tape from the mary result of increased mobility of the scapula inpostero-inferior angle of acromion across the spine the midrange of arm elevation accompanied by theat the medial border of the scapula); a lowered ratio lower and upper trapezius, serratus anterior and

1 The use of trade names is for product identification purposes only and does not imply endorsement.



middle deltoid showing myoelectrical signs of fa- sponds to an increased upward rotation during hu-tigue. McQuade et al.[57] suggested that, if excess meral elevation.[57,58,60]

motion of the scapula occurs, this might place in-3.3 Pathological Patternscreased stress on the glenohumeral capsular struc-

tures and lead to increased glenohumeral instability, Cumulative stresses may place excessive stressas currently shown by Weiser et al.[1] with an in- on the shoulder complex, the throwing gesture rep-creased tensile load on the inferior glenohumeral resenting a relevant example. Burkhart et al.[2] de-ligament created by excessive protraction of the fined the acronym ‘SICK’ (Scapular malposition,scapula. Inferior medial border prominence, Coracoid pain

Through two fatigue protocols, Ebaugh et al.[58]and malposition, and Dyskinesis of scapular move-

found a particularly important increase in upward ment) as a recognized overuse muscular fatiguerotation and external rotation of the scapula, mainly syndrome, which could entail shoulder pain in theduring a low-load, high-repetition protocol (the throwing athlete.[2,3] The hallmark feature of thishigh-load, low-repetition protocol entailed similar, syndrome consists of asymmetric malpositioning ofbut lower changes), accompanied by a decrease in the scapula in the dominant throwing shoulder. Thisthe level of activity across scapular muscles. statically observable position is suggestive of under-

Tsai et al.[59] induced muscle fatigue during an lying muscle activation alteration, which could pro-exercise in a glenohumeral external rotation with a duce altered kinematics of the scapula upon dynam-rubber band (until the subject could no longer per- ic use.[1-3,9,12] A thrower with this syndrome presentsform the task). They found that this entailed a signif- an apparent ‘dropped’ scapula in his dominanticant fatigue effect for all scapular rotations in the symptomatic shoulder in comparison with the scap-early to middle phases of humeral elevation, the ular position of the contralateral shoulder: viewedbiggest mean difference concerning the decrease in from behind, the inferior medial scapular borderposterior tilting. Additionally, they found fair to appears very prominent, with the superior medialgood correlations (r = 0.39–0.60) between the border and acromion being less prominent.[2] Forchanges in scapular posterior tilting and the amount Burkhart et al.,[2] this forward tilting and protractionof external rotator muscle fatigue; a disruption in the of the scapula is a consequence of tightness of thebalance between internal and external rotation tor- pectoralis minor as the coracoid tilts inferiorly andques would result in scapulothoracic motion modifi- shifts laterally away from the midline. The limita-cations.[59] Ebaugh et al.[60] found, with a similar tion of this theory is that it is based on observationexternal rotation fatigue protocol, less posterior tilt and they do not actually have scapular kinematicsof the scapula in the beginning phase of arm eleva- measurements.tion, accompanied by more scapular upward rotation Alterations of scapular position at rest or throughand clavicular retraction in the mid ranges of eleva- motion are commonly associated with injuries thattion. Changes observed in scapular kinematics may create clinical dysfunction of the shoulder.[8-10] Ac-affect the amount of area in the subacromial space cording to Kibler et al.,[8-10] these alterations, calledand may facilitate impingement.[59] To date, it re- ‘scapular dyskinesis’, do not suggest aetiology ormains unknown whether the observed changes in define patterns that correlate with specific shoulderscapular orientation are a primary result of direct injuries. However, classification of scapular dys-face alterations of the infraspinatus and teres minor kinesis patterns and positions can be of help inmuscles or something secondary to compensatory designing a treatment plan.[10] Kibler et al.[9,10] de-changes in the activity of the scapulothoracic mus- scribed four categories of dyskinetic patterns basedcles, which help maintain scapular stability.[59] on patient observation and which correspond to the

three planes of motion on the ellipsoid thorax.According to these different studies, fatiguetends to result in changed motion of the scapula, • Type I is characterized, at rest, by prominence ofwhich alters the scapulohumeral rhythm.[57-60] Gen- the inferior medial scapular border due to a rota-erally, the modification in scapula mobility accom- tion around the transverse axis through the sagit-panied by scapulothoracic muscle fatigue corre- tal plane.[9,10] During arm motion, the inferior



angle tilts dorsally and the acromion tilts ventral- rior scapular position with arm elevation (5.2 ± 1.6ly over the top of the thorax. cm below the first thoracic vertebrae) in comparison

with non-impaired subjects (7.5 ± 1.5 cm). Endo et• Type II corresponds, at rest, to the prominenceal.[30] observed, in shoulder subacromial impinge-(winging) of the entire medial scapular borderment syndrome evaluated on digital images at 0°,and represents abnormal rotation around a verti-45° and 90° of abduction, that both upward andcal axis (through the horizontal plane).[9,10]

external rotations of the scapula were impaired atDuring arm motion, the medial scapular borderthe painful arc angle of abduction. This tended to betilts dorsally at the thorax.more apparent for the external rotation of the scapu-• Type III represents a superior translation of thela than for the upward rotation, reducing availableentire scapula and prominence of the superiorclearance for the rotator cuff and greater humeralmedial scapular border due to a rotation aroundtuberosity as the shoulder was abducted.[30]the antero-posterior axis through the frontal

plane.[9,10] During arm motion, a shoulder shrink In a study by Hebert et al.,[62] 3-D scapular atti-initiates movement without the occurrence of tudes in symptomatic and asymptomatic shoulderssignificant winging of the scapular. of subjects with unilateral subacromial impingement

were found to be similar, and both the shoulders of• Type IV corresponds to the symmetrical scapularsubjects with impingement differed from the shoul-position, taking into account that the dominantders of healthy subjects, mainly through a scapulararm may be slightly lower.[9,10]

asymmetry in anterior tilting. The authors speculat-With respect to types I and II, Burkhart et al.[3]

ed that inappropriate neuromuscular strategies af-observed an abnormal position with excessive scap-fecting both shoulders might have been used.[62]ular protraction at rest and a decreased retractionThere is evidence that unilateral attitudes increaseduring cocking and early acceleration. In throwingthe tension level of shoulder and neck muscles onathletes, the alteration in stabilizer muscle functionthe other side of the body[63] and controlateral coac-may change the relationship between the glenoidtivation has been shown during maximal activity inand humerus as the arm moves through the throwingshoulder and neck muscles.[64] One way to confirmphases, causing abnormalities in force genera-this assumption would have been to record, duringtion.[12] Indeed, for most shoulder activities, theunilateral shoulder elevation, 3-D scapular attitudesscapula plays the link in the proximal-to-distal se-of the controlateral scapula and bilateral activationquencing of velocity, energy and forces; this se-during electromyography.[62]quencing starts at the ground and the individual

body segments, or links, are coordinated in their After a swimming session, Su et al.[18] observedmovement by muscle activity and body positions to no significant differences in scapular kinematicsgenerate, summate and transfer force through these (assessed with an inclinometer with the arm at rest,segments to the terminal link; this sequencing is and at 45°, 90° and 135° of humeral elevation) forusually termed the ‘kinetic chain’.[6,8,61] In the case healthy swimmers, despite muscle fatigue indicatedof ‘scapular dyskinesis’, the kinetic chain is then by a significant reduction in force generation (mea-interrupted as the unstable scapula aberrantly trans- sured with a hand-held dynamometer). However,mits the large forces generated from the ground the shoulder with subacromial impingement wasthrough the lower extremities and torso to the shoul- significant, accompanied by decreases in scapularder and arm.[4,8,16] upward rotation concomitantly with a decrease in

force developing in subjects after swimming.3.3.1 Impingement Syndrome Likewise, Ludewig and Cook[13] found a de-In comparison with non-impaired subjects (34.6 creased scapular upward rotation, increased anterior

± 9.7°), Lukasiewicz et al.[39] found that the shoulder tipping and increased scapular internal rotationwith subacromial impingement syndrome demon- under load conditions in a group with subacromialstrated a significantly lower posterior tilting of the impingement relative to a group without impinge-scapula in the sagittal plane (25.1 ± 9.1°). Subjects ment. At the same time, upper and lower trapeziuswith impingement also demonstrated a higher supe- muscle electromyographic activity increased in the



group with impingement and the serratus anterior patterns may have been missed in these cadavericmuscle demonstrated decreased activity across load studies.[66] Moreover, they only considered a singleand unload phases.[13] humeral orientation: 90° of elevation in the scapula

plane, with maximal internal rotation.[66] In a recentIn a case report of a tennis player with rightstudy, McClure et al.[20] observed slightly greatershoulder pain for 2 months, with a shoulder diag-scapular upward rotation and clavicular elevationnosis of stage II anterior shoulder impingement,during flexion and slightly greater scapular posteriorHost[65] observed the patient’s posture while he wastilt and clavicular retraction during scapular planestanding. He presented bilateral forward shoulders,elevation in an impingement group compared with awith the right shoulder more forward than the left

(‘forward’ was defined as the shoulder appearing control group; this could be interpreted as favoura-anterior from the coronal plane) from a lateral ble compensatory responses to increase subacromialview.[65] From a posterior view, the right scapula space. There were no differences in resting postureappeared to be more abducted from the vertebral between the groups.[20]

spinal processes than the left scapula. In addition to The results of Warner et al.,[17] employing thethese resting scapular position asymmetries, faulty static Moire evaluation (where the subject holdsscapulohumeral rhythm was thought to occur when both arms forward and flexed at 90° for 5 secondsthe patient flexed and abducted his right humerus: with 4–5 kg weights in each hand) demonstrated athe observed abnormality corresponded to an imme- scapulothoracic asymmetry in 57% of an impinge-diate and excessive scapular abduction and eleva- ment group versus only 14% among asymptomatiction and appeared to be mainly excessive (>60°) at subjects. Furthermore, their application of the dy-the end range (180°) of abduction and flexion.[65]

namic Moire test (where the subject lifts 4–5 kgThe low level of evidence of this case report is the weights simultaneously in both hands from 0° tolimitation of this article. 120° in the forward plane) demonstrated an abnor-

Schmitt and Snyder-Mackler[19] also described mal pattern in 100% of subacromial impingementthe secondary subacromial impingement syndrome subjects as against 18% in the normal group.[17]

of an overhead athlete resulting from scapulo-tho-Laudner et al.[24] assessed 11 throwing athletesracic muscle weakness (serratus anterior, middle

diagnosed with pathological internal impingementand lower trapezius) and resultant scapular instabili-of the supra-spinatus and infra-spinatus between thety. The specific targeting of treatment to strengthengreater tuberosity with the posterior-superior gle-the weak muscles resulted in a rapid return of func-noid labrum. They observed a statistically signif-tion.[19] Besides, Cools et al.[25] showed, in overheadicant increased sternoclavicular elevation and anathletes with subacromial symptoms, a decrease inincreased posterior scapular tilt position in the hu-force in the serratus anterior muscle (isokinetic eval-meral elevation from 30° to 120°, compared with theuation) and an imbalance in the lower trapeziuscontrol group.[24] This increase scapular elevationmuscle.may be an adaptation by the internal impingementKarduna et al.[66] showed an original approach ingroup to avoid a position of contact between thetheir study of eight glenohumeral fresh frozen hu-humeral head and the posterior-superior position ofmeral cadavers. Contrary to other studies aboutthe glenoid.scapular kinematic and impingement syndrome,

they showed that subacromial clearance decreased3.3.2 Unstable Shoulderwith an increase in upward rotation. Results demon-Investigating five fresh frozen cadaver shoulders,strated no significant effect of posterior tilting and

Weiser et al.[1] observed that, for anteriorly directedexternal rotation. Karduna et al.[66] suggested thatloads, there was increased in situ strain on the anteri-changes in upward rotation observed in patients withor band of the inferior glenohumeral ligament withimpingement syndrome may serve to open theincreased simulated scapular protraction. Thesesubacromial space. Major limitations in this studyfindings suggest that repetitive or chronic protrac-resulted from the lack of contact location measure-tion of the scapula may imply excessive strain and,ment and the fact that the effects of combination



ultimately, insufficiency in the anterior band of the affected side, the authors also reported alterations oninferior glenohumeral ligament.[1] the asymptomatic side.[22]

In a second study, the following was observed byEleven fresh frozen cadaver shoulders were stud-Von Eisenhart-Rothe et al.[21] during muscular re-ied by Itoi et al.[32] in order to examine the influencelaxation at 90° of abduction and external rotation: anof scapular inclination on inferior instability of theincreased glenohumeral translation (anterior–inferi-glenohumeral joint. In the sulcus test, all of theor) in traumatic unstable shoulders in comparisonshoulders dislocated when the scapula was down-with their respective contralateral side (3.6 ± 1.5 vswardly inclined at 15°. However, when the scapula0.7 ± 1.6 mm), and the same in both atraumaticwas upwardly inclined at 30°, none of the shouldersunstable shoulders through a non-uniform directiondislocated either in the sulcus test or with an applica-(4.7 ± 2 mm). During isometric muscle activity intion of a 1.5-kg load.[32] Itoi et al.[32] concluded thatthe same position (90° of abduction with externalscapular inclination contributes significantly to in-rotation), the humeral head became significantlyferior stability of the glenohumeral joint. They alsomore centred (p < 0.05) in comparison with itsconcluded that increased scapular upward inclina-position during muscular relaxation, but only intion prevents inferior displacement of the humeralshoulders with traumatic instability and not in thosehead, probably because of a ‘bony cam effect’. Anwith atraumatic instability. This observation sug-increase in the scapular inclination tightened thegested, in atraumatic instability, an alteration of thesuperior capsule and the increase in the slope of theactive stabilizers, and emphasized the paramountglenoid fossa acting as a bony cam further tightenedimportance of the rehabilitation process.[21]the superior capsule-ligamentous structures, thus

Glousman’s[67] evaluation of skilled athletes withstabilizing the humeral head in the glenoid fossa.[32]

an isolated diagnosis of anterior glenohumeral insta-The limitation of the cadaver study is that the dy-bility revealed electromyographic differences fromnamic stabilizers are taken out of the picture, andathletes having normal shoulders. In these athletestherefore applicability to the moving shoulder needswith instability, Glousman[67] recorded a markedto be interpreted with caution.decrease in activity levels on the pectoralis major,Von Eisenhart-Rothe et al.[22] hypothesized thatsubscapularis and latissimus dorsi (in fact, thesechanges in humeral head position correlate withmuscles contract eccentrically to protect the anterioralterations in scapular positioning. Using open mag-part of the shoulder joint) and he also observednetic resonance imaging, they examined, in variousdecreased activity of the serratus anterior through-arm positions, the shoulders of 28 healthy volun-out the pitch. Such serratus anterior activity reduc-teers and 14 patients with atraumatic instability.[22]

tion diminishes scapular rotation during the lateThey found that the glenohumeral to scapulotho-cocking motion, giving a possible decrease in theracic ratio in the scapular plane increased in 9 ofsubacromial space.[67]

14 atraumatic shoulders (corresponding to a de-creased upward rotation) and that the ratio decreased

3.4 Summaryin three patients.[22] At the same time, the internalscapular rotation in the transverse plane was in-

The healthy throwing athlete’s shoulder exhibitscreased in all unstable shoulders. The unstablea significantly increased upward rotation combinedshoulders also presented malcentring of the humeralwith a retraction of the scapula during humeralhead in the direction of instability during variouselevation in comparison with non-throwing athletes.arm positions.[58] In healthy and atraumatic unstableThis might represent an adaptive pattern warrantingshoulders, the correlation between scapular positionvital to injury-free performance by clearing the acro-and glenohumeral positioning was high during pas-mion for the underlying subacromial structures.sive elevation (r = 0.60–0.87), especially at 30° and

90° of abduction, suggesting that scapula position- The shoulder muscle fatigue induces a modifica-ing is relevant for humeral head decentring.[22] Inter- tion of scapula motion during humeral elevationestingly, in cases where altered scapular positioning (mainly an increased scapular upward rotation),and humeral centring were most prominent on the which alters the scapulohumeral rhythm. Alterations



of scapular position at rest or through motion (‘scap- could also give rise to scapular dyskinesis.[3,13,25,67]

ular dyskinesis’) are commonly associated with in- This implies that most of the abnormalities in scapu-juries that create clinical dysfunction of the athletic lar motion or position would have to be treated byshoulder. Classification of scapular dyskinesis pat- physical therapy in order to relieve symptoms asso-terns and positions can be of help in designing a ciated with inflexibility and to normalize muscletreatment plan. strength and activation patterns (figure 3).[10]

Classically, subacromial impingement syndrome Muscle inhibition or imbalance frequently findsresults in decreased upward rotation, increased ante- its roots in glenohumeral internal disturbance, suchrior tipping and increased scapular internal rotation as instability, labral tears, rotator cuff injury orduring humeral elevation. Likewise, periscapular tendonitis.[10] When structural problems, as well asmuscles have altered muscle activation patterns in the internal disturbance have been corrected, scapu-impingement patients. Abnormal scapulohumeral lar muscle rehabilitation may be initiated, focusingrhythm during humeral elevation have been linked on some specific factors.to imbalances in force production of the scapulotho-racic muscles. The internal impingement syndrome 4.1 Flexibilityis accompanied by a significant increased scapularelevation, which could be a position compensation The pectoralis minor, the sole anterior scapu-of the pathology. lothoracic muscle, is passively lengthened during

The unstable shoulder presents malcentring of the active scapular upward rotation, external rota-the humeral head into the glenoid fossa. Some corre- tion and posterior tipping that accompany arm ele-lations between scapular position and glenohumeral vation in healthy individuals.[27] A non-adaptivelypositioning during passive elevation suggest that shortened muscle would potentially limit these nor-scapula positioning is relevant for humeral head mal scapulothoracic motions, reduce the size of thedecentring. In atraumatic instability, an alteration of subacromial space, and then create an environmentthe active stabilizers emphasizes the paramount im- leading to pathology.[27] The pectoralis minor hasportance of improving the scapular muscle function also been identified as a muscle requiring stretchingthrough the rehabilitation process. in individuals with forward shoulder posture.[27] For

Burkhart et al.,[2] the anterior tightness may be treat-ed by placing a rolled towel between the shoulder4. Conservative Management ofblades of the supine patient and steadily pushingScapular Malposition – Rehabilitationposteriorly on the shoulders to stretch the pectoralisminor.Undoubtedly, classification of scapular dys-

kinesis patterns and positions may help to optimize Another issue with inflexibility is the lack of fulltreatment of shoulder disorders; we recommend that internal rotation of the glenohumeral joint causedscapular evaluation includes both static and dynam- by capsular or muscular posterior cuff tight-ic testing of motion.[10] Inflexibility of the muscles ness.[3,26,68-71] Borich et al.[26] demonstrated a signif-and ligaments around the shoulder can affect the icant relationship between glenohumeral internal ro-position and motion of the scapula;[3,26,27,37] like- tation deficit (measured with subject in supine posi-wise, weakness or alteration of muscle activation tion, shoulder 90° abducted in the frontal plane) and

Scapular dyskinesis:Causes and treatment

Muscular weakness

Capsular and/ormuscular tightness

Lack of proprioception

→ stretching → restoration of flexibility

→ strengthening → agonist-antagonist balance recovery

→ closed to open kinetic chain exercises → regain neuromuscular control

Fig. 3. Scapular dyskinesis: causes and treatment.



abnormal scapular positioning, particularly in- 4.2 Strengtheningcreased anterior tilt. The glenohumeral translationresulting when the capsule is asymmetrically tight The scapula acts as a base of support and anwas measured in the study by Harryman et al.,[68] anchor to which 17 different muscles firmly attach,and also in current researches.[69-71] Huffman et thereby justifying the view that scapulothoracic mo-al.[70] found that posterior capsular tightness alters tion is controlled by several force couples.[73]

the humeral head position most profoundly during Classical exercise techniques to strengthen thethe deceleration and follow-through phases of scapular muscles may enhance dynamic stabilitythrowing. Myers et al.[69] observed that tightening of during arm motion, while specific exercise drillsthe posterior elements of the shoulder may contrib- enhance the dynamic control of the scapulothoracicute to internal impingement in throwing athletes. A musculature.[72-74] These drills are designed to chal-tight posterior inferior capsule could also produce a lenge maximally the scapular force couples, whichSLAP lesion by pushing superiorly the humeral rest on:head towards the posterosuperior biceps labral at- • the upper trapezius counterbalanced by the lowertachment.[3,71] fibres of the serratus anterior;

• the middle trapezius/rhomboids opposed by theOn the basis of the clinical observation, one ofserratus anterior;the stretching techniques for the posterior capsular

• the lower trapezius and upper serratus anteriortightness is the ‘sleeper stretches’,[2] in which thefibres.[73,74]

athlete lies on his or her side with the shoulder in 90°Rehabilitation of patients with scapular dys-flexion and the elbow in 90° flexion. The shoulder is

kinesis should include the kinetic chain conceptinternally rotated passively by pushing the forearmbased on a proximal to distal control se-toward the table around a fixed elbow, which acts asquence.[2,10,74] This emphasizes the achievement ofa pivot point (figure 4). The roll-over sleeper stretchfull and appropriate scapular motion and the integra-is the same as the sleeper stretch except that thetion of that point into a subsequent, more global,shoulder is only flexed 50–60° and the patients rollsapproach including trunk and hip movements (scap-forward 30–40° from vertical side lying.[23] Theular retraction is facilitated by trunk and hip exten-cross-arm stretch has the patient standing with thesion).[10]

shoulder flexed 90° and passive adduction appliedOnce scapular motion is normalized, this move-by the non-dominant arm to the dominant el-

ment pattern serves as the framework for strengthen-bow.[23,72] Seemingly, this posterior stretch primari-ing exercises targeting the scapular muscles.[10] Thely stretches the posterior musculature to a greaterearly stages of strength rehabilitation include exer-degree than the posterior inferior capsule.[72]

cises in the closed kinetic chain and coordinatedactivation of all components in force couples, ratherthan isolated activation of individual mus-cles.[2,10,73,74] For example, a very safe exercise to beproposed in the early phase consists of the ‘low,middle or high row’: it involves trunk extension,scapular retraction and arm extension as the patientpushes against resistance in a posterior direction.[2]

More advanced closed-chain exercises include the‘scapular clock’ (figure 5), in which the hand isplaced on the wall, eliminating the weight of the armand moving the scapula in elevation and depression(the 12 and 6 o’clock positions), as well as retractionand protraction (the 9 and 3 o’clock positions).[2,74]

Thereafter, closed-chain exercises will include hu-meral head depressions and rotations on a ball, ‘wall

Fig. 4. ‘Sleeper stretch’ devoted to the capsular and muscularposterior cuff stretching.



a cb

Fig. 5. ‘Scapular clock’ (closed kinetic chain at: (a) 12 o’clock; (b) 9 o’clock; and (c) 3 o’clock positions).

washes’ (starting position in retraction of the scapu- the middle trapezius muscles (regarding the positionof the thumb-down or up). Blackburn’s retractionla, extension of the arm to protraction of the scapula,exercises are used to strengthen the scapular retrac-flexion of the arm) [figure 6] and ‘punches’ (figuretors and posterior rotator cuff.[2] Seated push-up7) [punch out may be varied: diagonal, upward orexercise stimulates, in particular, the scapular de-downward], which combine closed-chain shoulderpressor or retractors, the triceps, the latissimus dorsiactivation with open-chain arm motion. Hintermeis-and the teres major.[2]ter et al.[75] studied the muscle activity (measured by

electromyography) and applied load during shoulder On the basis of electromyographic analysis, Ek-rehabilitation exercises done with an elastic resis- strom et al.[77] and Ludewig et al.[78] observed thattance device such as seated rowing exercises, shoul- the standard push-up plus demonstrated the highestder shrug or forward punch exercises. These open- electromyographic activation of the serratus anteri-chain exercises target the rotator cuff and require a or. Moseley et al.[79] and Decker et al.[80] alsostable scapular base, since all the rotator cuff mus- analysed scapular muscle activity during selectedcles have their origin on the scapula. Indeed, closed- rehabilitation exercises: the exercises that main-chain exercises require less rotator cuff muscle acti- tained and upwardly rotated scapula while accentu-vation than open-chain exercises.[76] Likewise, verti- ating scapular protraction elicited the greatest elec-cal patterns, with the arm closer to the body, creating tromyographic activity from the serratus anteriora shorter lever arm, requires less activation than muscle.[80] The serratus anterior is also activateddiagonal patterns, with a long lever arm.[76]

maximally with exercises requiring a great amountof upward rotation of the scapula: as shoulder ab-Many other strengthening exercises are reportedduction in the plane of scapula above 120° and ain the literature; they allow a regaining of controldiagonal exercise with a combination of shoulderover scapular protraction, retraction, depression,flexion horizontal abduction and external rota-elevation and rotation (figure 8 and figure 9). Fortion.[77]

example, the patient lies on his or her side on theuninvolved arm, and the affected arm is abducted to Plyometric exercises (dynamic stretch-shorten-90° and internally rotated (figure 9), or the patient’s ing), such as the medicine ball toss and catch, orhand is placed on the table to fixate the distal seg- tubing plyometrics, will be initiated when scapularment, and the scapula is slowly elevated, depressed control and motion throughout the range of shoulderand protracted.[2] Ellen et al.[12] proposed scapu- elevation are recovered.[10] Cordasco et al.[81] ob-lothoracic stabilizer exercises using a light hand served a high level of activity of the upper trapeziusweight: the patient lies on their back with arms up during the acceleration phase during a two-handedstraight above their chest, and gently pushes their medicine ball throw. Their findings support the usearm higher (scapular protraction using serratus ante- of medicine ball training as a bridge between staticrior) or the patient lies on their stomach with their resistive training and dynamic throwing in the reha-arm hanging down comfortably, and lifts their arm bilitation of the overhead athlete.[81] Neuromuscularup slowly until it is just below parallel to floor and proprioceptive exercises represent the transition(horizontal abduction), soliciting the rhomboids or between the reinforcement and the use of the shoul-



stabilizers with the elbow high enough to keep theupper arm at or above the horizontal plane.[2,72]

On the basis of the underlying biomechanicalconcepts, the context of a ‘preventive approach’must be encouraged: strengthening of the scapularmuscles, stretching of the posterior rotator cuff andpectoralis minor muscle and retraction of the scapu-la during the throwing gesture.

4.3 Scapular Taping

Scapular taping might be helpful to decreaseexcessive abduction and winging and also to pro-Fig. 6. ‘Wall washes’ (closed kinetic chain).

mote upward rotation. Host[65] proposes that a firststrip would be applied, pulling proximally from theder through some specific functions and before theupper trapezius muscle belly region distally to ap-return to the field by the athlete.[5,74] The goals ofproximately 5–8 cm below the inferior angle of theawareness of proprioception are to re-establish af-scapula. Another strip would then be applied fromferent pathways from the mechanoreceptors at thethe posterior lateral carcomion diagonally across theinjured joint to the CNS and to facilitate supplemen-back and ending just lateral to the thoracic spinoustary efferent pathways as a compensatory mecha-process, in order to pull the scapula back into adduc-nism.[82] Humeral head and scapular stabilization ontion and slightly upward.[63]

unstable surface,[83] dynamic stabilization[82] orLikewise, Schmitt and Snyder-Mackler[19] intro-functional rehabilitation that mimics athletic func-

duced taping in a patient with an impingement syn-tion are called ‘proprioceptive neuromuscular facili-drome in order to improve scapular position duringtation exercises’.[82]

elevation, and to assist in the function of the scapulaBefore the return to the field, a transitory phase, stabilizers. The taping was used to prevent stretch-

which is conducive to integrating new instructions ing of the serratus anterior and middle and lowerduring the throwing gesture, is of paramount impor- trapezius by decreasing the winging scapula. Suchtance.[2,3,8,72] The leg and trunk are essential to pro- an adaptation decreases the demand placed on thesevide a stable base for arm motion, and a rotational muscles as well as on the glenohumeral musculaturemomentum for force generation; for example, these during daily activities.[19]

segments generate half of the total force and kinetic Lewis et al.[84] showed a statistically significantenergy in the tennis serve.[2] Inflexibility of the non- difference in scapular position with the tapingdominant hip and trunk, as well as weakness of hip among subjects with subacromial impingement syn-abductors or trunk flexors, break the kinetic drome. Changing posture was associated with achain.[2,6,83] This breakage increases lumbar lordosisin acceleration, which places the arm behind thebody.[2,6,83] Likewise, a hypersagittalization of thescapula creates a hyperabduction/external rotationposition of the throwing shoulder.[72] During the latecocking phase of the overhead throw, because thethrower’s humerus excessively abducts horizontallyand hyperangulates posterior to the plane of thescapula with a ‘dropped elbow’, posterior compres-sion loads on the structures, including the labrum,may occur.[2,72] One key point to avoiding thesecompensations is that the abducted arm must stay inthe plane of the scapula through use of the scapular Fig. 7. ‘Punches’ (open kinetic chain).



fined as an observable alteration in the position ofthe scapula and the patterns of scapular motion inrelation to the thoracic cage.

Laboratory measurements of scapular displace-ments are typically capable of quantifying the scap-ular kinematics in 3-D, but are not available to theclinical setting. Clinical measures (inclinometer,tape measure) are only capable of measuring scapu-lar kinematics in 2-D, but can easily be used by theclinician. Inclinometer assessment gives valid andaccurate information regarding static positions ofscapular upward rotation. A bilateral tape measure-ment between the inferior angle of scapula andspinous process, in three positions of the upperextremities (Lateral Scapular Side Test), provides aquantitative measurement of possible scapularasymmetry. The distance from the sternal notch tothe coracoid process at rest gives a quantitativemeasure of scapula internal rotation, which is corre-

a

b

Fig. 8. Scapular strengthening exercises including (a) retractionand (b) protraction.

lated with pectoralis minor muscle tightness.significant increase in the range of motion in shoul- Different patterns of abnormal motion in scapularder flexion and abduction in the plane of the scapula, dyskinesis are also described, based on simple bilat-thereby the point in the range of shoulder movement eral visual observation of scapular position with theat which the subjects experienced their pain was patient’s arms at rest at the side and during elevationsignificantly higher (p < 0.01). and lowering in the scapula plane. Classification of

Ackermann et al.[85] evaluated the effects of tap- scapular dyskinesis patterns and position may be ofing the scapula of violinists into a position that could help in designing a treatment plan.prevent excessive elevation and protraction while Healthy athletes shoulders show adaptive pat-playing. During violin playing of varied musical terns, particularly in the shape of significantly in-excerpts, scapula taping was associated with increased upward rotation combined with retraction ofcreased electromyographic activity levels in the up- the scapula. Fatigue, impingement (subacromial orper trapezius muscle, thus scapula taping may have internal) context, labral pathology or unstable shoul-acted to restrict forward and upward movement ofthe shoulder, thereby increasing the amount of iso-metric tension generated in the upper trapezius.[85]

Ackermann et al.[85] observed that taping had signif-icant negative effects on the subject’s reports ofconcentration and comfort; this was associated witha reduction in musical performance quality.

5. Conclusion

The scapula plays an important role in shoulderfunction. In sports in which demands placed on theshoulder are extremely high, the quality of move-ments depends on the interaction between scapularand glenohumeral kinematics. Set apart from thescapula’s normal status, ‘scapular dyskinesis’ is de- Fig. 9. Exercises for the scapular muscles in lying side.



6. Fleisig GS, Barrentine SW, Escamilla RF, et al. Biomechanicsder results in alterations of scapular position at rest.of overhand throwing with implications for injuries. Sports

Abnormal scapulohumeral rhythm during humeral Med 1996; 21: 421-377. Forthomme B, Croisier JL, Ciccarone G, et al. Factors correlat-elevation is also described. Even if scapular dys-

ed with volleyball spike velocity. Am J Sports Med 2005; 33:kinesis represents a nonspecific response to shoul- 1513-9der pathology, it is linked to weakness or alteration 8. Kibler WB. The role of the scapula in athletic shoulder function.

Am J Sports Med 1998; 26: 325-37of scapular muscle activation and inflexibility of the9. Kibler WB, Uhl TL, Maddux JWQ, et al. Qualitative clinicalmuscles (pectoralis minor, posterior rotator cuff) evaluation of scapular dysfunction: a reliability study. J Shoul-

der Elbow Surg 2002; 11: 550-6and ligaments around the shoulder. This implies that10. Kibler WB, McMullen J. Scapular dyskinesis and its relation tomost of the abnormalities in scapular motion or

shoulder pain. J Am Acad Orthop Surg 2003; 11: 142-51position must be taken into account through the 11. Poppen NK, Walker PS. Normal and abnormal motion of the

shoulder. J Bone Joint Surg 1976; 58: 195-201rehabilitation process.12. Ellen MI, Gilhool JJ, Rogers DP. Scapular instability: theThe pectoralis minor and the muscular posterior scapulothoracic joint. Phys Med Rehab Clin North Am 2000;

cuff tightness are classically treated with specific 11: 755-7013. Ludewig PM, Cook TM. Alterations in shoulder kinematics andstretching techniques. Exercises to strengthen the

associated muscle activity in people with symptoms of shoul-scapular muscles enhance dynamic stability during der impingement. Phys Ther 2000; 80: 276-91

14. Codman EA. The shoulder. Boston (MA): G. Miller and Com-motion, while specific exercise drills are designed topany, 1934challenge maximally the scapular force couples. Re-

15. McQuade KJ, Smidt G. Dynamic scapulohumeral rhythm: thehabilitation of patients with scapular dyskinesis effects of external resistance during elevation of the arm in the

scapular plane. J Orthop Sports Phys Ther 1998; 27: 125-33should include the kinetic chain concept based on a16. Kibler WB, Sciascia A, Dome D. Evaluation of apparent andproximal to distal control sequence. Before the re- absolute supraspinatus strength in patients with shoulder injury

turn to the field by the athlete, neuromuscular and using the scapular retraction test. Am J Sports Med 2006; 34:1643-7proprioceptive exercises represent a transition be-

17. Warner JJP, Micheli LJ, Arslanian LE, et al. Scapulothoracictween the muscle reinforcement and the use of the motion in normal shoulders and shoulders with glenohumeral

instability: a study using Moire topographic analysis. Clinshoulder through specific functions. We recommendOrthop Rel Res 1992; 285: 191-9the regular use of assessments throughout a treat-

18. Su KPE, Johnson MP, Gracely EJ, et al. Scapular rotation inment programme of scapular disorders in order to swimmers with and without impingement syndrome: practice

effects. Med Sci Sports Exerc 2004; 36: 1117-23establish improvements and to individually bring up19. Schmitt L, Snyder-Mackler L. Role of scapular stabilizers into date the rehabilitation techniques. etiology and treatment of impingement syndrome. J Orthop

Sports Phys Ther 1999; 29: 31-820. McClure PW, Michener LA, Karduna AR. Shoulder functionAcknowledgements

and 3-dimensional scapular kinematics in people with andwithout shoulder impingement syndrome. Phys Ther 2006; 86:The authors thank A. Depaifve for her kind and efficient 1075-90

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