MR Imging of the Rottor Cuff nd Rottor Intervl Mrcelo R Areu nd Michel Recht Antomy of the Rottor Cuff The rottor cuff is comprised of the suprspintus, infrspintus, suscpulris, nd teres minor muscles nd tendons. The four muscles of the rottor cuff ct s stilizers of the glenohumerl joint. The suprspintus is primrily shoulder ductor. The suprspintus muscle origintes long the dorsl surfce of the scpul. The muscle fiers course in lterl orienttion nd converge to form n nterior tendon lthough there is lso second smller posterior tendon of the suprspintus. The suprspintus tendon is ordered superiorly y the sucromil-sudeltoid urs nd inferiorly y the joint cpsule. Anteriorly, the more distl suprspintus tendon converges with the corcohumerl ligment, nd posteriorly it merges with the nterior fiers of the infrspintus tendon. At the distl spect of the rottor cuff, the suprspintus nd infrspintus tendons sply out nd interdigitte, forming common continuous insertion on the middle fcet of the humerl greter tuerosity. The suprspintus tendon is est evluted in the coronl olique plne nd the sgittl olique plne, with the ltter eing helpful in evluting the most nterior fiers of the suprspintus. The region just medil to the convergence of the posterior fiers of the suprspintus nd the nterior fiers of the infrspintus hs een referred to s the posterior rottor intervl [1]. The infrspintus muscle externlly rottes the shoulder, originting in the infrspinous foss. The infrspintus hs multipennte configurtion, usully with three tendons, with the myotendinous junction hving somewht fnlike configurtion. The infrspintus is est evluted in the coronl olique nd sgittl olique plnes [1, 2]. M.R. Areu (*) Hospitl Me de Deus, Cost 40, Porto Alegre, RS 90110-270, Brzil e-mil: mrcelord@gmil.com M. Recht NYU Lngone Medicl Center, 660 First Ave., New York, NY 10016, USA e-mil: Michel.Recht@nyumc.org The teres minor muscle origintes long the upper two thirds of the lterl order of the scpul nd lends into the posterior glenohumerl joint cpsule more distlly. The infrspintus nd teres minor externlly rotte the shoulder, with the former lso eing n ductor nd the ltter eing wek dductor. The suscpulris muscle is strong dductor nd internl rottor. The suscpulris muscle origintes from the suscpulr foss long the nterior spect of the scpul. It inserts primrily on the lesser tuerosity, with superficil fiers extending to the greter tuerosity. Similr to the infrspintus, the suscpulris hs multipennte configurtion. The deep fiers of the suscpulris tendon lend with nd reinforce the nterior cpsule of the glenohumerl joint. The mid nd distl portions of the middle glenohumerl ligment lend with the cpsule nd deep fiers of the suscpulris efore inserting into the lesser tuerosity. The suscpulris is est evluted in the xil nd sgittl olique plnes. MR Imging On MR imging, norml, helthy tendon should pper with low signl intensity on ll sequences. There re however, some exceptions/pitflls to this sttement. One exception is tht on short TE imging the mgic ngle phenomenon my result in incresed signl in regions where the tendon courses t 55-degree ngle in reltion to the min mgnetic field. Mgic ngle rtifct should resolve on T2-weighted (long TE) sequences, thus differentiting it from true tendon pthology. Additionlly, volume verging etween the tendon nd djcent tissues such s muscle, fsci, ft, nd crtilge my result in incresed tendon signl on short TE imging. Agin, use of T2-weighted imging nd ssessing tendons in t lest two plnes cn increse confidence in differentiting volume verging from true intrtendinous signl normlities. The tendon microntomy itself cn led to flse pthologic dignosis especilly when using high resolution imging, when visuliztion of tendon fscicles cn simulte ters nd tendinopthy. Better understnding of Springer Interntionl Pulishing AG 2017 J. Hodler et l. (eds.), Musculoskeletl Diseses 2017-2020, DOI 10.1007/978-3-319-54018-4_19
M.R. Areu nd M. Recht tendon microntomy, such s tendon fusions (exmple: distl fusion of suprspintus nd infrspintus tendons ner the footprint) nd norml multipennte configurtion of some tendons of the cuff, cn minimize flse positive dignosis. Impingement Syndromes In 1972 Neer stted tht the vst mjority of rottor cuff pthology ws secondry to impingement ut it is now felt tht the etiology is multifctoril with contriutions from impingement, vsculr insufficiency, ging nd/or metolic conditions. There re two types of impingement, externl nd internl impingement syndromes. Externl impingement syndromes include sucromil nd sucorcoid impingement. Sucromil impingement, which is the most common impingement syndrome, occurs with overhed ctivities. It occurs secondry to impingement of the cuff, primrily the suprspintus tendon, within the corcocromil rch (Drwing 1). The impingement cn e cused y primry structurl normlities of the rch such s cromioclviculr osteophytes, n normlly shped cromion such s hooked cromion, sucromil enthesophytes, or n os cromile (Fig. 1). MR findings of sucromil impingement include tendon chnges, structurl normlities of the corcromil rch nd sucromil-sudeltoid ursitis. In sucorcoid impingement the suscpulris tendon is impinged etween the corcoid nd the lesser tuerosity. Findings in sucorcoid impingement include nrrowing of the corcohumerl intervl, prtil rticulr sided ters of the suscpulris tendon nd sucorcoid ursitis. Internl impingement syndromes include oth posterosuperior nd nterosuperior impingement. In posterosuperior impingement the undersurfce of the posterior cuff ecomes entrpped etween the humerl hed nd the posterior glenoid when the rm is ducted nd externlly rotted. Although contct my e physiologic in this position, with constnt repetition, such s in overhed thletes, it cn led to ttrition nd prtil ters of the undersurfce of the cuff s well s ters of the posterior superior lrum nd osteochondrl chnges in the greter tuerosity. Drwing 1 Hnd drwing of shoulder ntomy. () Coronl view of the osseous nd ligmentous components of the sucromil tunnel formed y the cromium, the corcoid, the corcocromil ligment nd the corrcoclviculr ligment, with the suprspintus tendon pssing inside the tunnel. () Sgittl view of osseous nd ligmentous rch
MR Imging of the Rottor Cuff nd Rottor Intervl Anterosuperior impingement is much less common thn posterosuperior impingement nd occurs when the suscpulris tendon is trpped etween the nterior humerl hed nd the nterosuperior glenoid nd lrum during forwrd flexion of the rm. Tendinosis (Tendinopthy) Fig. 1 Coronl olique T1-weighted imge showing cromioclviculr joint degenertive chnges with inferior osteophytes cusing suprspintus impingement Tendinosis histopthologiclly refers to tendon degenertion with collgen fier disorienttion, incresed intrsustnce deposition of mucoid, nd sence of inflmmtory cells (thus the term tendinitis is inpproprite). The typicl MR ppernce of tendinosis is norml signl intensity ssocited with morphology chnges (Figs. 2 nd 3). The signl chnges of tendinopthy typiclly re of intermedite c Fig. 2 Coronl olique T2-weighted ft suppressed imges showing sucromil ursitis nd tendinosis of suprspintus (), infrspintus () nd intr-rticulr portion of long hed of iceps tendon (c)
M.R. Areu nd M. Recht Fig. 3 () Sgittl T2-weighted ft suppressed imge showing tendinosis of the superior fiers of suscpulris (rrows), note the intr- rticulr thick long hed of the iceps tendon superiorly with mild signl normlity consistent with mild tendinosis () xil T2-weighted ft suppressed imge demonstrtion high signl of the superior fiers of the suscpulris tendon, not s intense s fluid, chrcterizing focl tendinosis signl on oth short nd long TE imging. In prticulr with tendinosis there is no fluid-like signl intensity on long TE imges. This llows one to differentite tendinosis from frnk tendon tering. Becuse of the pitflls descried ove tht cn led to intermedite signl on short TE imges in norml tendons, we elieve tht one should e very hesitnt to cll tendinopthy in tendons with norml morphology. The ssocited morphology chnges typiclly consist of norml thickening of the involved tendon. Clssiclly, rottor cuff ters occur in the insertionl fiers of the cuff tendons in regions of preexisting tendinopthy [3]. MR Imging of Tendon Ters Tendon ters re clssified into full thickness or prtil thickness ters. Full thickness ters re suclssified s complete or incomplete depending on if ll or only some of the tendons of muscle re involved. Prtil thickness ters re sudivided y the loction of the ter into rticulr-sided, intrtendinous, nd ursl-sided ters. Although rottor cuff ters typiclly pper s res of fluid signl intensity on T2-weighted imges, in out 10% of ters, the region of tendon discontinuity is low in signl on T2-weighted imges, possily ecuse of chronic scrring nd firosis. These ters my e visulized t MR rthrogrphy ecuse intrrticulr contrst fills the ter. On conventionl MR imging, secondry signs of cuff ter, such s tendon retrction (mesured in the medil-lterl dimension), my e the only indiction of full-thickness ter. Prtil Ters Prtil-thickness rottor cuff ters cn e descried ccording to the surfce of the tendon involved s well s the percentge of tendon involved (Drwing 2). Prtil-thickness rticulr surfce ters re chrcterized y focl region of fier discontinuity tht is filled with fluid-like signl intensity on T2-weighted imging. Ftsuppressed T2-weighted imging cn increse lesion conspicuity y etter demonstrting the high T2 signl tendon defect). Articulr surfce ters re the most common type nd re esily dignosed with stndrd MR imging when joint effusion is present (Fig. 4). In the sence of joint effusion, rticulr surfce prtil-thickness ters my e difficult to identify, prticulrly in the setting of grnultion tissue or scrring. Delmintion of the involved portion of the tendon my occur, most often involving the rticulr surfce of the suprspintus tendon (Drwing 3). Delminted ters cn led to cyst formtion within the ssocited or djcent muscle, the so clled sentinel cyst. Those cysts usully re restricted to the muscle elly nd typiclly do not cuse symptoms, in contrst to the prlrl gnglion cysts tht my cuse nerve compression. Intrsustnce or conceled ters re chrcterized y intrtendinous T2 fluid-like signl without extension to either the ursl or rticulr surfce (Fig. 5). These lesions will not fill with gdolinium on MR rthrogrphy ecuse of lck of communiction etween the ter nd the rticulr surfce of the tendon. Intrsustnce ters will not e seen y the rthroscopist s they do not communicte with the tendon surfce.
MR Imging of the Rottor Cuff nd Rottor Intervl Drwing 2 Hnd drwing of prtil thickness ter types (coronl view of the suprspintus tendon). 1. Intrsustnce footprint ter with djcent one cyst. 2. Intrsustnce ter. 3. Bursl side ter. 4. Undersurfce ter Drwing 3 Prtil thickness undersurfce delminted ter Fig. 4 Coronl olique T2-weighted ft suppressed imge showing suprspintus prtil thickness undersurfce ter, nd cromioclviculr joint degenertive chnges with inferior osteophytes Fig. 5 Coronl olique T2-weighted ft suppressed imge showing prtil thickness intrsustnce ter t the footprint, with djcent one mrrow edem, tendinosis nd ursitis Prtil-thickness ursl surfce ters demonstrte norml incresed T2 signl long the superior (ursl) surfce of the tendon (Fig. 6). The rticulr surfce remins intct. When there is fluid in the sucromil urs, the ters re well visulized, prticulrly on T2-weighted imges. However, these ters my not e visile on T1-weighted MR rthrogrphic imges s the intr-rticulr gdolinium will not enter the gp in the tendon ecuse of intct rticulr surfce fiers. In ddition, the presence of ursl fluid my not e pprecited on T1-weighted imging. For these resons, it is crucil to include t lest one T2-weighted sequence on ll MR rthrogrphic exms to ssess for fluid- filled ursl surfce ters. The extent of the prtil ter cn further e
M.R. Areu nd M. Recht Fig. 6 () Coronl olique T2-weighted ft suppressed imge showing prtil thickness ursl side ter of the suprspintus tendon, tendinosis nd sucromil ursitis. () Sgittl T2-weighted imge demonstrting the prtil thickness ursl side ter, trnsverse length Tle 1 Extent of prtil ter of the rottor cuff tendons Grde I for ters < 3 mm Grde II for extension 3 6 mm Grde III if > 6 mm Fig. 7 () Coronl olique T2-weighted ft suppressed imge showing full thickness ter of the nterior fiers of the suprspintus tendon. () Sgittl T2-weighted imge demonstrting the suprspintus full thickness ter trnsverse length declred ccording to the depth; commonly used grding system is shown in (Tle 1) [4, 5]. Full Thickness Ters Ters of the suprspintus tendon most commonly rise t the nterior spect of the tendon immeditely djcent to its ttchment onto the greter tuerosity (Fig. 7). Suprspintus ters cn extend posteriorly into the infrspintus tendon or nteroinferiorly through the rottor intervl to involve the medil spect of the corcohumerl ligment nd superior suscpulris tendon fiers, sitution tht is ssocited with more severe suprspintus trophy nd poor prognosis [6]. A full-thickness suprspintus ter llows communiction etween the rticulr nd the ursl comprtments. Infrspintus tendon ters re often ssocited with suprspintus tendon ters nd my e oserved in younger thletes with overhed ctivities nd posterosuperior
MR Imging of the Rottor Cuff nd Rottor Intervl Drwing 4 () Schemtic illustrtion of the ntomy of the glenohumerl joint in ABER position. 1 Humerl hed, 2 Glenoid, 3 Acromion. () Detil illustrtions demonstrte: ter with torn edge of the rticulr surfce. (Modified from Schreinemchers SA, et l (2009) Detection of prtil-thickness suprspintus tendon ters: is single direct MR rthrogrphy series in ABER position s ccurte s conventionl MR rthrogrphy? Skeletl Rdiol 38:967 975) impingement, in which there is often n rticulr side delmintion of the cuff. The so-clled ABER view (duction nd externl rottion rm position) in conventionl MRI or MR rthrogrphy hs een proposed to increse the sensitivity for detection of these ters. For younger ptients nd ptients suspected of hving posterior superior impingement nd prtil-thickness undersurfce ters, the ABER position is vlule in demonstrting lesions of posterior superior impingement nd undersurfce ters of the rottor cuff s well s non-displced ters of the nterior inferior lrum in ptients with glenohumerl instility [7, 8] (Drwing 4). Teres Minor tendon ters re rre nd present most commonly s prtil ters ccompnied y infrspintus ters. When descriing rottor cuff ters there re numer of fetures tht need to e descried: the size, retrction, ter shpe, nd sttus of the muscle Size The size (AP dimension) of full thickness ter hs importnt implictions on oth the decision to perform surgery s well s the surgicl pproch, the postopertive prognosis, nd the possiility of ter recurrence. DeOrio nd Cofield clssified rottor cuff ters on the sis of gretest dimension [9] s show on Tle 2. Tle 2 Rottor cuff full thickness ters DeOrio nd Cofield clssifiction smll medium lrge mssive Retrction Retrction is defined s the medil-lterl extent of the ter. We cn mesure the retrction ssuming its origin t the footprint or give informtion out its loction regrding the cromioclviculr (AC) joint. The tendon cn e lterl to the AC joint, t the AC joint or medilly to the AC joint. It hs een suggested tht ter is suspected to e irreprle if MR imging depicts retrction medil to the AC joint, lthough this is controversil. Shpe <1 cm 1 3 cm 3 5 cm >5 cm The shpe of rottor cuff ter is importnt in the selection of surgicl technique. Ters cn e clssified rthroscopiclly into three sic shpes ccording to the ter geometry s viewed from the tendon surfce: crescentic, U shped
M.R. Areu nd M. Recht c Drwing 5 Full thickness ter shpe. Drwings illustrte U-shped ter () crescentic ter () nd n L-shped ter (c). (Modified from Morg Y, et l (2006) MR imging of rottor cuff injury: wht the clinicin needs to know. Rdiogrphics 26:1045 1065) nd L shped (Drwing 5). In crescentic ters, the tendon pulls wy from the greter tuerosity ut typiclly does not retrct fr medilly nd therefore cn e rettched to one with miniml tension. In crescenteric ters the nteroposterior dimeter of the ter is greter thn its medil-lterl dimeter. In L nd U shped ters the medil-lterl dimension of the ter is greter thn the ntero-posterior dimension. The difference etween the L nd U ters is whether or not the nterior or posterior ttchments of the tendon re intct (U shped) or disrupted (L shped) (Drwing 5). Muscle Sttus When rottor cuff tendons re torn it is importnt to evlute the ssocited muscle elly for its sttus, prticulrly the presence of ny ftty trophy (Fig. 8). The presence of
MR Imging of the Rottor Cuff nd Rottor Intervl c Fig. 8 () Coronl olique T2-weighted ft suppressed imge showing full thickness totl surfce ter of the suprspintus tendon with retrction, crnil migrtion the humerl hed, nd impingement with the superior lrum. ( nd c) Coronl olique nd sgittl T1-weighted imges showing trophy of the suprspintus muscle with ftty infiltrtion ftty trophy is considered poor prognostic sign nd contrindiction for surgery. Qulittive ssessment of the ftty degenertion of the rottor cuff muscles cn e mde using the Goutllier clssifiction [10], initilly descried for computed tomogrphy nd lter dpted for MR (Tle 3). Tle 3 Goutllier clssifiction of muscle ftty degenertion Stge 0 Norml muscle without ft Stge I Few ftty streks within the muscle Stge II Less ft thn muscle within the muscle Stge III Sme mount of ft nd muscle within the muscle Stge IV More ft thn muscle within the muscle
M.R. Areu nd M. Recht Miscellneous Conditions Clcific Tendinitis Hydroxyptite deposition disese (HADD) typiclly ffects middle-ged persons nd represents common cuse of joint pin, relted primrily to perirticulr deposition of clcific mteril within tendons. Asymptomtic hydroxyptite deposits re common, nd my e found in the perirticulr soft tissues of virtully every joint. Clinicl symptoms rnge from chronic or recurrent joint pin ssocited with limited rnge of motion to cute severe pin nd tenderness. It is estimted tht HADD fflicts 3% of the symptomtic dult popultion nd 7% of those with shoulder pin. The shoulder is the most commonly ffected region, where symptomtic HADD is usully referred to s clcific tendinitis, or clcific ursitis, or clcific tendinoursitis. The criticl zone of the suprspintus tendon (pproximtely 1 cm from its insertion in the greter tuerosity) is, y fr, the most frequently ffected site. It is common for hydroxyptite deposits of the rottor cuff to migrte to djcent tissues such s sucromil urs, long the course of the tendon towrd the myotendinous junction, or less commonly intr-osseously. The clcific deposits hve gloulr ppernce nd lowsignl intensity t ll MR imging sequences (Fig. 9) When the clcifiction deposits migrte to ones, muscle or urse, there is ssocited incresed signl intensity with T2 weighted MR imging sequences ecuse of the inflmmtory process tht develops with the migrtion (most symptomtic stge of the disese). After nd during the migrtion we cn oserve incresed ursl fluid or tenosynovil fluid (when djcent to long hed of the iceps tendon). After tht very symptomtic stge the clcifiction deposits cn resor nd evenly dispper. It cn e difficult to pprecite smll mounts of clcifiction of MR nd the use of rdiogrphs or ultrsound my e helpful to confirm the presence of clcifictions [11 13]. Muscle Denervtion Etiologies for denervtion include oth inflmmtory conditions such s cute rchil neuritis nd compressive neuropthies. Fluid-sensitive MR sequences such s T2 ft sturted nd short tu inversion recovery, or STIR, re useful for detecting the incresed T2 weighted signl ssocited with cute denervtion. T1-weighted imging is idel for depicting ftty infiltrtion nd muscle trophy secondry to chronic denervtion. Acute rchil neuritis, lso known s Prsonge-Turner syndrome, my result in trumtic shoulder pin nd wekness, therey mimicking rottor cuff ter. Although the pin my resolve in weeks or months, wekness of the ffected muscles my persist nd result in ftty trophy. Although the suprspintus nd infrspintus re typiclly ffected, the deltoid nd rhomoid muscles my lso e ffected. The most common cuse of nerve compression round the shoulder is compression of the suprscpulr nerve y Fig. 9 () Coronl olique T1-weighted imge showing clcific tendinitis of the infrspintus tendon visulized s focl low signl intensity hidroxiptite deposits t the footprint. () Axil T2-weighted ft suppressed imge showing infrspintus clcifiction s low signl intensity nd inflmmtory rective one mrrow s high signl intensity
MR Imging of the Rottor Cuff nd Rottor Intervl prlrl cysts secondry to lrl ters. The suprscpulr nerve courses through the suprscpulr notch to enter the suprspintus foss where it gives off rnches to the suprspintus muscle nd then courses through the spinoglenoid notch to enter the infrspintus foss nd gives off rnches to the infrspintus muscle. The level of nerve compression cn e inferred y identifying the involved muscles. Involvement of oth the suprspintus nd infrspintus implies more proximl compression t the level of the suprscpulr notch, while isolted infrspintus involvement is consistent with disese ffecting the nerve t the level of the spinoglenoid notch. The xillry nerve courses in the qudrilterl spce nd cn suffer entrpment in this loction, leding to the qudrilterl spce syndrome. MR imging cn e useful for detection the etiology of the nerve compression. which cn e secondry to prlrl cysts or y firous nds, which my e difficult to identify on MR imging. Isolted edem/ftty trophy of the teres minor muscle my e detected, sometimes ccompnied y edem/ftty trophy of the deltoid. If no structurl normlity is demonstrted, secondry signs of denervtion ecome importnt in iding the dignosis of qudrilterl spce syndrome [14 16]. Rottor Intervl The rottor intervl, the tringulr shped region demrcted y the corcoid process medilly nd the converging mrgins of the suprspintus nd suscpulris tendons lterlly, contins severl structures importnt for the stility nd proper iomechnicl functioning of the shoulder. These include the corcohumerl ligment (CHL), the superior glenohumerl ligment (SGHL), nd the intr-rticulr portion of the long hed of the iceps tendon (LHB). The CHL rises from the lterl spect of the corcoid process nd inserts on oth the lesser tuerosity (the medil nd of the CHL) nd on the greter tuerosity (the lterl nd of the CHL). The medil nd of the CHL lends with the fiers of the SGHL to form the iceps pulley (sling) tht surrounds the medil nd inferior spect of the intr-rticulr portion of the LHB. The lterl nd of the CHL surrounds the superior nd lterl spect of the intr-rticulr LHBT efore inserting on the greter tuerosity of the humerus. The SGHL is fold of the glenohumerl joint cpsule tht hs vrile origin nd inserts on the humerus just ove the lesser tuerosity. The LHB rises from the posterosuperior lrum, the suprglenoid tuercle or comintion of oth. The tendon courses oliquely through the rottor intervl efore it exits the joint in the intertuerculr groove. The iceps pulley plys n importnt role in the stility of the intr-rticulr iceps tendon. It limits medil suluxtion of the tendon when the rm is ducted nd externlly rotted. The superior insertion of the intr-rticulr suscpulris tendon lso provides medil support of the iceps tendon y contriuting to the medil wll of the icipitl groove. Disruption of the pulley cn led to instility of the tendon with either suluxtion or disloction. Disruption cn occur secondry to trum [17] or overuse, such s repetitive overhed ctivity [18]. In ddition, the pulley cn e injured in ssocited with ters of the fr nterior suprspintus nd fr superior suscpulris tendons tht extend to involve the corcohumerl nd/or superior glenohumerl ligments [18, 19]. The clinicl dignosis of iceps pulley lesions cn e difficult nd it is lso frequently difficult to identify normlities of the pulley on MR imging, ecuse of the smll size of the ntomic structures involved, unless there is ssocited iceps suluxtion/disloction. There re two min clssifiction systems of iceps pulley injuries, the Bennett [20] nd Hermeyer [21] clssifictions, which re sed on the ntomic structures injured. References 1. Mingw H, Itoi E, Konno N et l (1998) Humerl ttchment of the suprspintus nd infrspintus tendons: n ntomic study. Arthroscopy 14(3):302 306 2. 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