Investigations for the Unstable Shoulder

Transcription

1 Symposium Asin Journl of Arthroscopy 2017 Jn-April ;2(1): 7-14 Investigtions for the Unstle Shoulder Astrct Introduction INTRODUCTION The shoulder hs the gretest rnge of motion compred to ny joint in the ody, however, this moility comes t the expense of stility. Unlike other ll nd socket joints, the glenohumerl joint (GHJ) relies more on its soft tissue restrints rther thn its ony congruity to chieve lnce etween rnge of motion nd stility. The glenoid is deepened y the firous lrum nd the joint cpsule hs thickenings in the form of glenohumerl ligments (GHLs) of which the inferior or inferior GHLs (IGHL) is the mjor ligmentous stilizer. It hs n nterior nd posterior nd with n xillry pouch situted etween. It is the nterior nd tht is criticl to pssive joint stiliztion. Injuries to these ony or soft tissue components cn led to instility. It runs from the nteroinferior lrum to form sleeve of continuous tissues with the glenoid rim, cpsule, nd periosteum to the humerl metphysis. Importntly for stility, ut lso for dignosis, it ecomes tught in the position of duction nd externl rottion or ABER. When there is 1 Deprtment of Orthopedics, Norfolk nd Norwich University Hospitl, Norwich, Englnd, 2 Deprtment of Orthopedics, University College Hospitl, London, Englnd. Address for Correspondence: DR Jonthn Negus, Deprtment of Orthopedics, University College Hospitl, London, Englnd. E-mil: jonthn.negus@cnt.net 1 2 Oliver Jmes Negus,Jonthn Jmes Negus The unstle shoulder hs wide spectrum of presenttions from the ovious disloctions to the sutle chronic instilities. It is the jo of the clinicin who is interpreting the imging to correlte cler history with the pthology tht cn e seen nd to go serching for the pthology tht my not e ovious ut could drsticlly lter mngement. For most cses, imging is used minly to direct further mngement thn to dignose. Therefore, it is criticl to hve ccess to the pproprite imging modlity tken in the correct mnner to mximize the possiility of picking up ll lesions. This review looks t the possile lesions nd imging modlities needed to dignose them nd more importntly, direct their future mngement. Keywords: Shoulder instility, Shoulder imging, Unstle shoulder, Shoulder disloction. pthology of the lroligmentous complex in this re, the IGHL is incompetent nd the shoulder ecomes unstle [1,2]. There re numer of imging investigtions tht cn e used to dignose normlities in these structures nd in this review we look to highlight the most importnt investigtions used in this ssessment of the cute nd chronic unstle shoulder. Suluxtion is prtil loss of contct etween the joint surfces nd disloction is complete loss of contct. Suluxtion nd disloction cn e cute or chronic nd while it is commonly cused y trum, it cn e trumtic s well. Instility of the GHJ descries pthologicl stte in which this excessive trnsltion leds to pin nd loss of function. Instility cn e unidirectionl (nterior, posterior, or inferior) or multidirectionl. Glenohumerl shoulder instility is most common in young mle dults, with nerly hlf of ll disloctions occurring in those etween the ges of 15 nd 30-yer-old. Of ll GHJ disloctions presenting to emergency deprtments, more thn 2/3rd Dr. J. Negus Dr. O. Negus 2017 y Asin Journl of Arthroscopy Aville on doi: /j This is n Open Access rticle distriuted under the terms of the Cretive Commons Attriution Non-Commercil License ( which permits unrestricted non-commercil use, distriution, nd reproduction in ny medium, provided the originl work is properly cited. re mle [3].The custive trum is commonly sports relted. Importntly, the younger ptients with n cute trumtic disloction hve higher recurrence rtes for nteroinferior disloctions thn older ptients [4,5]. This needs to e considered when ssessing the imging for this ge group, s they re more likely to need surgery. The younger ptients re lso more likely to dislocte from higher-energy injury in preciously norml shoulder cusing dmge to their joint crtilge nd the lro-ligmentous complex. Older ptients re more likely to dislocte from low-energy fll in shoulder with pre-existing degenertive chnge or rottor cuff pthology. Imging Imging investigtions re the minsty for dignosing nd plnning mngement of n unstle shoulder. These include plin X- rys, fluoroscopy, ultrsound scns (USS), computed tomogrphy (CT), nd mgnetic resonnce imging (MRI). Arthroscopy cn lso e used s dignostic investigtion. While imging modlities hve dvnced over the yers, especilly with threedimensionl (3D) reconstructions of CT nd MRI imges, plin rdiogrphs remin the first investigtion nd for good reson. They re chep nd esy to otin nd cn provide significnt informtion, especilly in cse of cute disloction. The most relevnt views when investigting instility re stndrd nteroposterior (AP) of the shoulder, n AP of the GHJ, lterl trns-scpulr Y-view, xil views, nd Stryker notch views. Pre-reduction imges cn pick up suluxed or dislocted joint. Post reduction films re importnt to 7 Asin Journl of Arthroscopy Volume 2 Issue 1 Jn-April 2017 Pge 7-14

2 Figure 1: An nteroposterior nd lterl plin rdiogrph of n cute nterior disloction. chrcterize ny residul suluxtion or ssocited ony lesions such s ony Bnkrt or Hill Schs lesion. However, ny suspicion of ony lesion necessittes ssessment with 3D imging. USS is more useful when detecting ssocited soft tissue lesions or lesions tht hve developed s prt of picture of chronic instility. These include rottor cuff ters; rupture, tendinosis nd suluxtion of the iceps tendon; joint effusions; prlrl cysts suggestive of lrl ter; suprscpulr nd xillry nerve pthology s well s pthology in the cromioclviculr (AC) or sternoclviculr joints. It hs the dvntge of eing dynmic investigtion, which is noninvsive, reltively chep, nd esy to otin. However, it hs limited use in visulizing the GHJ. CT is most useful for chrcterizing osseous lesions including frctures, ony Bnkrt lesions, Hill Schs lesions s well s glenoid remodeling. It cn ssess one qulittively, quntittively nd morphologiclly t high resolution. If it is comined with intrrticulr contrst medium, the resultnt CTrthrogrphy cn e used to ssess the lrum, cpsule rticulr crtilge nd intrrticulr loose odies. It is reltively inexpensive ut does involve ionizing rdition. It cn e useful lterntive to MRI if ptient hs contr-indictions such s pcemker. MRI nd MR rthrogrphy is the investigtion of choice for detiled ssessment of the soft tissues of the shoulder. MRI is prticulrly useful for ssessing full thickness rottor cuff ters, rottor cuff muscle trophy nd iceps pthology. MR rthrogrphy cn dd detil when ssessing prtil thickness rndomised controlled trils, rticulr surfces, intrrticulr loose odies, the cpsule, nd the lro-ligmentous complex. There is little use for MR rthrogrphy in the cute setting due to the rthrogrphic effect of the effusion or hemrthrosis. MR imges should e otined in severl plnes. The coronl olique imges re prllel to the suprspintus tendon in either proton density (PD), PD with ft suppression (FS) or short T1 inversion recovery (STIR) sequences. This plne is most useful for ssessing rottor cuff ters. Sgittl imges re otined in the plne perpendiculr to the long xis of the suprspintus tendon. They ssess the rottor cuff in the short xis useful to look t muscle ulk. Figure 2: () Anteroposterior nd () scpulr Y view rdiogrphs of Hill Schs lesion. Axil imges re very useful for instility ecuse in ddition to evluting rthropthy of the GHJ nd AC joints nd ssessing the long hed of the iceps in the icipitl groove, this plne is most useful for ssessing lrl pthology. The more common sequences re T2 weighted grdient echo nd FS-PD. MR rthrogrphy is more sensitive for ssessing lrl pthology thn conventionl MRI ut 3T MRI hs een shown to improve the ssessment of these lesions without the need for contrst medium. The MR imges re either T1-weighted with ft sturtion for gdolinium contrst or PD/T2-weighted if sline is used. The MRI should e performed s soon s possile fter injection to tke dvntge of mximl joint distension. Indirect MR rthrogrphy cn e used when n intrvenous injection of gdolinium is given nd scn performed fter minutes of gentle exercise. There is no joint distension ut cn e useful if n rthrogrm cnnot e performed. If the ptient hs lredy hd surgery then the resultnt scrring, ltered ntomy nd implnt rtefcts cn pose chllenge. While non-metllic or titnium fixtion cn help, using STIR or fst spin echo cn help reduce the susceptiility of FS sequences to Figure 3: () X-ry of reverse ony Bnkrt lesion,() lesion seen on computed tomogrphy. Figure 4: (-c) Bony Bnkrt lesion seen on computed tomogrphy imges. 8 Asin Journl of Arthroscopy Volume 2 Issue 1 Jn-April 2017 Pge 7-14

3 Figure 5:() Norml sgittl T2 mgnetic resonnce,() humerl vulsion of glenohumerl ligment with effusion. Figure 6:Anterior lrl periostel sleeve vulsion. rtefct. Other investigtions for n unstle shoulder my include vsculr or electroneurologicl studies if there is clinicl suspicion for neurovsculr pthology, ut these won t e covered in this review. As clinicins, we will e presented with clinicl picture either from our own ssessment or from the request form tht hs een sumitted to rdiology. Therefore, logicl pproch to descriing the investigtions is to discuss wht ech offers in the most common clinicl scenrios tht tend to e present. Acute first time disloctions Acute shoulder disloction is clinicl dignosis sed on history nd exmintion. The immedite nd long-term mngement should e sed on the results of suitle rdiologicl investigtions. The first-line rdiologicl investigtion is plin film rdiogrphy, which hs the mjor dvntge of eing quick nd esily ccessile in the vst mjority of emergency deprtments. There re numer of views tht cn e otined ut the im is to otin minimum of 2 orthogonl views of the GHJ to determine the direction of the disloction nd visulize ny ssocited ony injuries. These re typiclly the Hill Schs lesion [6] which is present in 84% of cute nterior disloctions [7] nd the ony Bnkrt lesion [8]. However, it is not uncommon to tke series of etween 3 nd 5 views s ech view offers specific dvntge to evlute portion of the joint ut not the joint in its entirety (Fig. 1). The minimum rdiogrphic series for n episode of cute instility is n AP view nd lterl view. The idel lterl is n xillry lterl view s it gives view of the lesser tuerosity, the nterior nd posterior glenoid rims nd ny nterior or posterior trnsltion of the humerl hed on the glenoid. It my not e possile to otin in trum s it involves duction of the rm, idelly to 90. The plte is plced on the superior spect of the shoulder nd the em is pssed from Figure 3: ( & ) Mgnetic resonnce imges of Hill Schs lesion. etween the rm nd the chest in superior direction. There is trum xillry view tht does not require rm duction s the X-ry plte is plced directly under the shoulder with the ptient lening ck nd the em is positioned directly ove. The lterl or scpulr Y view gives cler indiction of the position of disloction ut offers limited informtion on ssocited on injuries, especilly ony Bnkrt lesions. The imge is otined y plcing the nterior spect of the shoulder ginst the X-ry plte, then plcing the X-ry tue posteriorly, long the scpulr spine (Fig. 2). Other views include the Stryker notch view, which ssesses for Hill Schs lesion nd the West point xillry view, which is useful in ssessing nterior glenoid normlities [9]. In ddition to immedite dignosis, plin films re used to ssess the joint postreduction nd ssess the need for immedite dditionl intervention. The disdvntge of plin film rdiogrphy is tht it does not ssess the degree of soft-tissue dmge. If soft tissue trum is left undignosed nd untreted then ptients re likely to encounter lxity nd thus further chronic instility, especilly in the younger ge group nd those in high-risk sporting or working situtions. Further imging is therefore n essentil prt of the rdiologicl work-up for ptients presenting with cute shoulder instility. If plin films do not clerly show or quntify suspected lesion, 3D imging with CT is often necessry. CT cn e used for ssessment of cute shoulder instility, 9 Asin Journl of Arthroscopy Volume 2 Issue 1 Jn-April 2017 Pge 7-14

4 Figure 5:() Norml sgittl T2 mgnetic resonnce,() humerl vulsion of glenohumerl ligment with effusion. however, it is not s commonly used s MRI. It is prticulrly useful in ptients who hve contrindictions for MRI nd those who hve metl implnts in or round the shoulder tht would cuse MR rtefct. CT is good for chrcterizing the size nd loction of osseous defects prior to surgicl intervention nd 3D reconstructions re useful to clculte nd pln [10]. With modern MRI sequences, CT nd MR hve now een shown to hve comprle results in terms of quntifying the degree of osseous defects [11]. Conventionl CT hs much more limited role in ssessing degree of soft tissue involvement. CT rthrogrphy, which involves imging the joint following intr-rticulr injection of contrst gent cn e used to investigte for crtilginous defects when MRI is not ville ut with poorer resolution nd incresed ionizing rdition, its use is limited (Fig. 3) [12]. The mjority of cses of cute instility will need further imging using MRI. MRI cn e used with or without n intrrticulr injection of contrst gent, typiclly gdolinium. This MR rthrogrphy isn t necessry in the cute setting s the effusion or hemrthrosis distends the joint nd cts s nturl contrst to highlight lesions of the lro-ligmentous complex. In the more chronic setting, the intr-rticulr contrst gent performs this jo. The use of pproprite ft suppressed or STIR sequences, highlights fluid in the soft tissues llowing delinetion of cute injury y demonstrting joint effusions, leeding, soft tissue, nd ony edem. The quntity nd qulity of the informtion necessry for plnning future mngement is mximl within the first 7-10 dys of the injury. As will e seen in those ptients with chronic instility, scr tissue nd tissues remodeling cn reduce the sensitivity of MRI to picking up soft tissue injury when the scn is distnt to the trumtic event [13]. Lesions The most common soft tissue injuries in cute instility re the Bnkrt lesion, Perthes lesion, glenolrl rticulr disruption (GLAD) lesion, humerl vulsion of glenohumerl ligment (HAGL) lesion, nd nterior lrl periostel sleeve vulsion (ALPSA). All these lesions hve chrcteristic findings on MRI [14]. Bnkrt lesions, which re vulsion injuries of the glenoid lrum re est identified on T2-weighted imging. The lesions pper s liner incresed signl in the normlly lowsignl ntero-inferior lrum. The Bnkrt lesion is present in 73% of cute nterior disloctions [7]. If ssocited with n vulsion frcture of the lrum off the glenoid rim the lesion cn e seen on X-ry nd CT imges (Fig. 4). Perthes lesions re similr to the Bnkrt lesion, in tht the lrum is seprted from the glenoid rticulr crtilge; however, the periostel sleeve is not ruptured. On conventionl MRI in neutrl rm position, it my e difficult to identify the lesion s the lrum my e only minimlly displced. For this reson, they re often left undignosed nd only discovered during surgery, however, studies hve shown tht MRI in ABER cn yield significntly higher detection rtes over MR in neutrl position [13]. The GLAD lesion is n nteroinferior lrl ter tht is ssocited with n injury to the glenoid rticulr crtilge. The IGHL is the most importnt soft tissue stilizer of the shoulder, hence disruption t the humerl insertion is highly likely to c led to chronic nterior instility nd is criticl to identify on MRI. This is known s HAGL lesion. It is uncommon for the HAGL to e ssocited with ony vulsion (Fig. 5). The ALPSA is Bnkrt lesion where the lro-ligmentous complex hs rolled up nd displced medilly leving re glenoid rim. It hs high ssocition with chronic instility (Fig. 6). In the dys nd weeks following disloction one edem my e seen on the imging [10] which my id in the identifiction of smll Hill Schs nd other osseous lesions. The identifiction of typicl pttern of one edem is especilly useful if the history is uncler for n instility episode (Fig. 7). The Hill Schs defect is the most common ony lesion following nterior disloction ut glenoid rim frcture is more concerning. While displced rim frgment my lock reduction in the cute setting, the rim frcture hs higher prognostic significnce for recurrent disloction thn Hill Schs lesion. The risk increses with n increse in size of the frgment [15, 16, 17]. When the shoulder disloctes posteriorly, it is reverse Hill Schs nd reverse Bnkrt lesions tht predominte. In this cse, 29- yer-old mn ws tckled plying rugy nd fell wkwrdly. He herd crck nd ws unle to move his shoulder. It ws reduced in the field. When ssessed week lter, the post reduction imging demonstrted posterior lrl ter (reverse Bnkrt) nd reverse Hill Schs lesion indictive of posterior disloction (Fig. 8). Effusions nd hemrthroses re often eneficil in identifying shoulder pthology following cute disloction. The high-signl fluid cuses distension of the joint cpsule, filling defects nd llowing structures to seprte, therefore cting s nturl contrst [12]. Bnkrt lesions re more esily identifile whilst n effusion is present, s the fluid clerly fills the defect etween the vulsed lrum nd the glenoid. Chondrl defects re more esily detectle in GLAD lesions [18] nd injury to the GHL, s seen with HAGL lesions, cn e loclized y the ssocited perirticulr edem nd hemorrhge in the xillry pouch, qudrilterl spce, nd proximl humerus round the lesser tuerosity [19]. Further evidence for HAGL lesions my e 10 Asin Journl of Arthroscopy Volume 2 Issue 1 Jn-April 2017 Pge 7-14

5 the J sign, which is incresed signl from edem nd hemorrhge round the torn stump of the IGHL [20]. For injuries with less effusion, or when imging is otined fter the effusion hs susided, then MR rthrogrphy is n option. The contrst gent works in much the sme mnner s n effusion, stretching the cpsule nd contrsting with the structures inside the cpsule. This llows qulity imging to e otined much lter fter the initil complint of instility. The drwck to rthrogrphy is the invsive nture of contrst dministrtion [12]. It requires fluoroscopic guidnce of intrrticulr dministrtion of the contrst solution, which cn e time-consuming nd crry the risks ssocited with ny joint injection: infection, leeding nd pin. Although these drwcks exist, MR rthrogrphy is generlly very well tolerted nd the enefit of mking n ccurte dignosis nd inititing the correct tretment fr outweighs the risks of the procedure. With the dvent of 3T MRI, the incresed resolution hs llowed improved visuliztion of mny soft tissue lesions without the need for rthrogrphy, ut this technology is not widely ville outside of the mjor centers. Acute shoulder instility cn e investigted with dignostic rthroscopy. This llows visuliztion of the contents of the shoulder cpsule nd is the stndrd tht mny studies into ccurcy of imging modlities compre their results ginst. It lso llows for n exmintion under nesthesi, which cn llow for clinicl findings not possile in n pprehensive, wke ptient. However, compred to imging, it is n expensive, invsive procedure with ssocited risks of nesthesi nd surgery nd hence is not recommended for dignostic purposes unless imging modlities re not ville or hve yielded no stisfctory results [21]. The cost of dignostic rthroscopy fr outweighs tht of MR imging: US$480 (+US$132 for 45 min of nesthesi) versus US$67 (ll prices sed on US Helthcre in 2014) [22]. For these resons, rthroscopy tends to e limited to therpeutic purposes. It is importnt to note tht ll these lesions hve een descried s they relte to nterior instility nd disloction. In cses of posterior disloction, the common lesions re the reverse Bnkrt nd reverse Hill Schs. They re locted opposite to their nmeskes in the AP plne. Chronic instility with repeted disloctions Similrly to cute instility, chronic instility cn e cused y trumtic event or rise without ny ntecedent trum. The ltter tends to e in ptients with generlized hypermoility. These hypermoile ptients my show miniml MRI findings. In the chroniclly unstle ptients, s with the cute disloction, imging is necessry to mke surgicl plns s well s just for dignosis. In fct, in post-trumtic ptients who continue to endure repeted GHJ instility episodes, the clinicl dignosis is cler. The role of imging in this sitution ecomes the need to chrcterize the ssocited pthology nd pln future surgery to ddress lesions. The surgicl plnning will e sed on the need to reconstruct ny osseous lesions of the glenoid or humerl hed, soft tissue lesions of the lro-ligmentous complex or oth. When ssessing the inferior cpsulolrl soft tissues in chronic disloctor, oth the investigtions used nd the lesions tht re found re similr to those of n cute ptient. It is less common to encounter hemrthroses, HAGL nd other cpsulr injuries. It is more common to find cpsulr lxity, Bnkrt lesion, n ALPSA, Hill Schs lesion, glenoid rim deficiency or frcture of the greter tuerosity in chronic repeted disloctors [23,24]. Glenoid rim frctures nd rottor cuff ters occur in roughly the sme proportions in ptients with cute nd chronic instility ut more frequent in ptients with repet disloctions. The prevlence of Hill Schs lesion increses from 25% in 1st time disloctors to etween 40% nd 90% in recurrent disloctors [24,25]. The chrcter of the lesion cn chnge over time with n increse in size seen in individuls with repeted episodes nd the development of signture htchet morphology over time [26]. It is intuitive tht the loction nd orienttion of the lesion depends on position of humerl hed during disloction nd the mgnitude of the compressive force during the trum [26].The loction nd mgnitude is importnt to direct the need for surgicl mngement nd wht surgicl option will e employed. The Hill Schs lesion cn cuse symptoms of ctching, clicking nd popping [27]. If lrge enough, the lesion cn engge the glenoid rim in the position of instility. Engging is cused when the lesion extends in size to include prt of the rticulr surfce nd so in ducted nd externlly rotted position, the glenoid rim flls into this lesion. Symptoms rnge from pprehension nd suluxtion in mild cses to locking nd disloction in severe cses. Surgicl mngement includes remplissge, one grft with llogrft, spce fillers, Lterjet procedure, resurfcing rthroplsty or even hemirthroplsty. The choice of surgicl mngement is driven y the position nd size of the lesion ut lso the ptient s symptoms. While imging is used to quntify the lesion preopertively, whether lesion is engging or not is judged cliniclly. Instility rising from glenoid pthology cn e from lck of one or from insufficiency of nteroinferior lroligmentous complex. If there is significnt loss of one, there cn e n rticulr incongruency which leds to mechnicl mismtch. The glenoid rim cn e pthologiclly flt or deficient post frcture or ony remodeling or oth [28]. Imging is used to quntify the size of lesion nd qulify rim contour. The risk fctors for instility from glenoid pthology re s follows: AP width of defect mesures 21% or more of totl glenoid length Totl rticulr surfce decreses y 20-30% [16,17] Inverted per shpe. Surgicl mngement is dictted y the degree of chnge: If loss<15% of width or 10% of re Soft tissue repirs 15-30% or 10-25% of surfce Bone ugmenttion in physiclly ctive >30% width or >25% re Glenoid 11 Asin Journl of Arthroscopy Volume 2 Issue 1 Jn-April 2017 Pge 7-14

6 reconstruction, ltrjet procedure. The use of CT scns hs trditionlly een the imging modlity of choice using oth two-dimensionl nd 3D reconstructions to quntify the re nd width of one losses. The use of CT rthrogrphy improves soft tissue evlution ut limits corticl one evlution s the iodinted contrst mteril cn hve sme ttenution s corticl one. Therefore, MRI is still needed to evlute soft tissues ppropritely. Now tht MRI is yielding similr levels of informtion of the corticl one, CT is eing used less frequently. It is worth noting tht mny chroniclly unstle ptients experience cute events on ckground of chronic instility nd their imging should e evluted with this in mind. An MRI of n cute disloction on ckground of chronic instility my still demonstrte hemrthrosis nd one mrrow edem overlying chronic findings. It is essentil to hve ccess to detiled history when ssessing the imging of n instility episode to ensure tht cute chnges do not msk the sometimes more sutle chronic lesions. Mny of the lrl-ligmentous lesions seen with glenohumerl instility occur t the time of the cute disloction s discussed erlier in the chpter. However, mny lso evolve over time, fter the cute first time disloction. The severity of these chronic soft tissue lesions depends on the initil energy of the first trum, the ssocited lesions incurred t the time nd the susequent level of ctivity of the ptient nd the numer of susequent disloctions they hve suffered. The Bnkrt lesion cn occur with the first disloction or fter multiple events. It cn chnge morphology from eing nondisplced to eing displced. This is evident on MRI, s the glenoid rim ecomes re or deficient nteroinferiorly. GLAD lesions develop with susequent disloction s chondrl flps increse in size nd detch from the glenoid foss leding to focl crtilge loss nd loose odies. This cn led to degenertive chnges nd osteorthritis with its clssic suchondrl sclerosis s well s ony remodeling of the glenoid. An ALPSA lesion cn rise from Perthes lesion (see cute instility) nd is common in recurrent disloctors. If the periosteum remins ttched to lrum, trction is trnsmitted long the IGHL nd the periosteum is stripped from the medil glenoid neck. Over time, the lrlligmentous complex then retrcts medilly with periosteum, over time. This rolled-up soft-tissue then scrs down ecoming immoile. This cn men it is oscured from view t rthroscopy y smooth synovilized surfce tht is creted s it hels. There is chrcteristic pttern of findings on MRI, which shows deficient or re glenoid rim on the xil nd olique coronl imges. If the lrum is sent, it my e found medilly s focl soft tissue thickening 5-15mm medil to glenoid rim [29,30]. If the IGHL is identified, it cn e followed to thickened periostel sleeve. This is mde esier using n MR rthrogrm, with or without ABER positioning. The HAGL nd cpsulr lesions re more likely to e identified if the MRI imges re tken soon fter the trumtic event. During the heling process, the IGHL cn scr down to humerus nd pper to hve norml contour t rthroscopy. If it does not scr down, the resultnt mechnicl insufficiency cn cuse chronic instility. The cpsulr defect t the humerl ttchment cn led to the development of pseudo-pouch, which is djcent to the norml xillry pouch. It is difficult to identify on non-rthrogrphic MRI unless the shoulder joint is distended y n effusion. When seen on MR rthrogrm, it gives the ppernce of two pouches. In the months nd yers following trum, pseudo pouch suggests the dignosis of HAGL lesion [19]. There is ony HAGL vrint which represents corticl frcture from the periostel vulsion. This my e visulized more clerly on CT scn. Chronic instility without repeted disloctions This group of ptients presents gret chllenge to clinicins. The symptoms occur due to repeted suluxtion nd micromotion. There re numer of synonyms used to descrie their clinicl picture including reltive instility, functionl instility, micro-instility, nd occult recurrent suluxtion. These should ll e orne in mind if evluting imging is requested using these clinicl terms. The request my lso e querying other pthology such s rottor cuff ter, impingement or superior lrum AP ter. It is, therefore, criticl to consider GHJ instility in the evlution of imging for ll young dult shoulders. The ptients my not present with ovious instility ut my hve n overuse ctivity, generlized cpsulr lxity or hve suffered remote trum mening it hs een forgotten out or it ws disloction tht relocted immeditely nd now seen s not importnt. The most common sports involved re swimmers, sell pitchers, weight lifters, nd tennis plyers. They only complin of pin ut this is due to functionl instility. There is grdul filure of oth their pssive nd dynmic shoulder stilizers. The IGHL stretches out long with the joint cpsule leding to tering of the nteroinferior lrum, delmintion of rticulr crtilge over ntero-inferior glenoid foss. The symptomtic thlete my hve cpsulr stretching tht isn t pprent on MRI ut micro-instility hs cused them to develop secondry rottor cuff ters, lrl ters, nd lesions of the long hed of iceps. The symptomtic overhed thlete my hve n nteroinferior lrl ter on the MRI ut with no loss of function. In fct, pitchers my develop nteroinferior lrl ter s n dptive chnge to improve their performnce, llowing greter ABER during lte cocking nd erly ccelertion. Ptients with generlized cpsulr lxity re lso ctegorized with the pneumonic trumtic, multidirectionl, ilterl, rehilittion, nd inferior cpsulr shift. They hve cpsulr lxity nd glenohumerl hypermoility which is excerted y repetitive overstretching, proprioceptive imlnce nd connective tissue deficiency. Their functionl imittion is due to involuntry GH instility. They hve no history of trum nd rthroscopic findings re often limited to cpsulr redundncy in xillry pouch. Lrl ters nd osseous lesions re typiclly sent. Arthrogrphy my lso suggest cpsulr redundncy, ut there re no relile dignostic criteri. The tretment is rehilittion with 12 Asin Journl of Arthroscopy Volume 2 Issue 1 Jn-April 2017 Pge 7-14

7 physiotherpy rther thn surgery unless solutely necessry. The results of surgery re disppointing minly due to the inherently lx tissues which stretch out over time. In ptients who re unwre of their trum, MRI imging my e delyed for weeks or months from the time of injury. They hve the sme risks of lrl-ligmentous complex lesions s first time disloctors ut ny one mrrow edem is likely to hve resolved. Cpsulr defects my hve heled nd even remodeled nd non-displced lrl frgments cn scr to the glenoid rim. Lrl-ligmentous lesions such s Bnkrt or Perthes lesions cn esily e overlooked in sence of ny evidence of previous disloction such s the edem ssocited with Hill Schs lesion. As with cute lesions, MR rthrogrm cn improve dignostic ccurcy s contrst cn fill the lrl defects in non-displced lesions nd outline norml contours. The ABER position trnsmits tension from IGHL to lrum, incresing dignostic confidence s the position cn displce n occult lesion from the glenoid rim. Conclusions Glenohumerl instility cn present with rod rnge of symptoms nd clinicl scenrios. The dignosis is ovious in some situtions ut most unstle shoulders hve never dislocted. Imging investigtions cn e used to dignose in those for whom the clinicl history isn t cler-cut. However, instility is clinicl dignosis - A Hill Schs lesion is mrker of disloction ut not instility. Imging dignosis depends on clinicl scenrio therefore choice of imging modlity lso does. References 1. Kim SH, H KI, Jung MW, Lim MS, Kim YM, Prk JH. Accelerted rehilittion fter rthroscopic Bnkrt repir for selected cses: A prospective rndomized clinicl study. Arthroscopy 2003;19(7): Itoi E, Hsu HC, An KN. Biomechnicl investigtion of the glenohumerl joint. J Shoulder Elow Surg 1996;5(5): Aoud JA, Soslowsky LJ. Interply of the sttic nd dynmic restrints in glenohumerl instility. ClinOrthopRelt Res 2002;400: Itoi E. Pthophysiology nd tretment of trumtic instility of the shoulder. 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