osteochondritis dissecans, mr imaging

7/29/2019 Osteochondritis Dissecans, MR Imaging

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O steochond ritis D issecans o f th eK nee : V a lue o f M R Im ag ing inD e te rm in ing Les ion S tab ility and theP resence o f A rticu la r C a rtilag e D e fec ts

A rthu r A . D e Sm et1D avid R . F ishe r1

Ben K . G ra fR icha rd H . Lange2

Rece iv ed A pr il 2 , 1 990 ; acc ep ted a fte r rev is ionMay 7 , 1 99 0 .

I D ep ar tm en t o f R ad io lo gy , U niv ers ity o f W is co n-s in C lin ica l S c ie nce C en te r , 6 00 H igh lan d Ave .,M ad is on , W I 5 37 92 . A dd res s re p rin t req ues ts to A .A . D e Sm e t.

2 D iv is ion o f O rth op ed ic Su rge ry , U n iv e rs ity o fW iscon s in C lin ic a l S cien ce C en te r, M ad iso n , W I53792 .03 61 -80 3x /90 /1 5 53 -05 49C Am e ric an R oen tge n R ay So c ie ty

O s teochondn tis d is secans is a le s io n o f ar ticu la r surfa ces th a t is o f unce rta in e t io lo g y .Th ese le s io n s a re seen on rad iog raphs as a bony de fec t o r fragm en ta tio n o f th esubchond ra l bone . A bony de fec t m ay be an actua l su rfa ce ho le o r the de fec t m ay befille d w ith fib rous tissu e o r f ib ro ca rt ila g e . S im ila r ly , th e appa ren t bone fragm en ts m aybe on ly p artia lly a ttach ed so th ey ar e unstab le and p rone to d isp lac em en t o r th e y m aybe firm ly a tta ched w ith fib rous tis sue . K now ledge o f fragm en t s tab ility and the pre senceo f an a rtic u la r c ar tila g e de fec t is u se fu l in d ec id in g on tre a tm en t. Th is in fo rm atio n canno tbe de te rm ined on p la in film s or c lin ica l e xam ina tion . W e co rre la ted M R exam in a tio n sw ith ar th ro scop ic fin d ing s in 21 pa tie n ts w ith os teo chondn tis d iss ecans o f th e knee tose e if M R im ag ing cou ld be used to p red ic t les io n s tab ility and articu la r c ar tilag e de fe c ts .A h ig h-s ig na l in te rfa c e be tween th e le s io n and th e fem ur w as used as ev id ence o fle s io n in s tab ility and w as found in 15 le s io n s . O ne of th ese les io ns w as questio n ab lys tab le a t su rg ery ; th e rem a inder w e re uns tab le and partia lly a ttach ed . The o th e r s ixpa tie n ts h ad d is p la ced fragm en ts w ith la rg e a rticu la r de fec ts tha t w e re c le ar ly v isu a lize do n th e M R exam in atio ns .

W e conc lude th a t M R im ag ing is u se fu l in eva lu a tin g a rtic u la r su rfac e defe c ts andle s io n s tab ility in p a t ie n ts w ith o s teo chondn tis d is secans .

AJR 155 :549 -553 , Sep tem be r 1 990

O s teochond ritis d issecans (OCD ) o f a fem o ra l condy le is a common a rtic u la rle s ion in ado lescen ts and young adu lts . A lthough m ost le s ions a re though t to betraum a tic in o rig in , o ther p roposed causes in c lude m echan ica l s tre s s , fam ilia ld ysp la s ia , pe riphe ra l a vascu la r nec ros is , and fa t em bo li [1 , 2 ].

In som e pa tien ts w ith O CD , the dec is ion o f w he ther to ope ra te im m ed ia te ly o rm anage conse rva tive ly can be d ifficu lt [3 , 4 ]. T he p la in film s m ay show e ithe r asubchond ra l bone de fec t o r fragm en ta tion o f the subchond ra l bone . If the re arepa rtia lly a tta ched ca rtila ge or bone fragm en ts , the fragm en ts shou ld be fix ed o rd rille d to he lp hea ling , o r they shou ld be debnded [5 -7 ].

P la in film s and c lin ica l e xam ina tion canno t de te rm ine w he the r fragm en ts area tta ched firm ly o r on ly pa rtia lly . A cco rd ing ly , a num ber o f techn ique s inc lud ingrad ionu c lide bone scann ing [4 , 8 -1 0 ], com pu ted a rth ro tom ography [1 1 ], and MRim ag ing [1 0 , 1 2-1 4 ] have been u sed to de te rm ine the s ta tu s o f OCD les ions .W e report o u r expe rience in us in g MR im ag ing to eva lu a te les ion sta b ility a nda rticu la r ca rtila ge de fec ts in 21 pa tien ts w ith d is ta l fem o ra l O CD in w hom a rth ro -scop ic co rre la tio n o f the find ings w as ava ila b le .

M a ter ia ls and M e thodsMR scans o f the knee s w e re ob ta in e d in 4 7 pa tie n ts w ith O CD of one o f th e fem o ra l

cond y le s . The 21 pa tie n ts w ho a lso had arth ro scop ic e va lua tio n and trea tm en t o f O CD fo rmth e bas is o f th is re po rt. T h e re we re 1 8 m en and th ree w om en w ith a n a ve rage age o f 1 9yea rs (ra n ge , 1 2-35 ). T he ad jacen t g row th p la te w a s c los ed in 1 7 o f the 21 pa tie n ts . A ll the


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pa tien ts had ch ron ic kn ee pa in . Two pa tie n ts had had knee pa in fo r5 and 7 m on th s , respe ctive ly ; th e rem a inde r h ad h ad pa in fo r 2 -15yea rs . T h ree o f the pa tien ts w ho had a h is to ry o f m ild knee pa in w e reshown to ha ve a cu te ly d isp la ce d bone fragm en ts on rad io g raph s .

The c lass ific a tion o f p la in film fin d in gs d ev ised by H ugh ston e t a l.[2 ] w as used to de te rm ine the lo ca tion o f the le s ions on the fem ora lcondy le . O n the an te rop os te rio r film s , on e les io n was in th e fem ora lno tch ; 1 5 in vo lve d the no tch and a po rtion o f th e cen tra l su rface o fthe condy le ; an d fiv e w e re lo ca liz ed to th e cen tra l, no nm en is ca lpo rtio n o f th e condy le . O n th e la te ra l f ilm s , 1 9 les io ns we re d ire c tlyd is ta l to a lin e p ro je c ted down the po s te rio r co rtex o f th e fem u r, tha tis , o n the we ig h t-b e a ring su rfa ce w h ile th e pa tie n t w as s ta n d ing . Twole s io ns we re p oste rio r to th is line in a p os ition o f loa d ing w ith kn eefle x io n , s uch as w hen c lim b in g s ta irs .

A ll e xam in a tion s we re pe r fo rm ed on a 1 .5 -T G ene ra l E lec tr ic S ig n aM R un it (M ilw au kee , W I) w ith a ded ic a te d tra nsm it-a nd -re ce ive e x -trem ity co il. S lic e th ic kness w as 3 mm w ith an in te rs lic e gap o f 1 .5mm . The fie ld o f v iew wa s 1 2-1 6 cm w ith a m atr ix o f 2 56 x 1 28 ;tw o exc ita tio ns w ere u se d . S p in -e ch o im ag in g w as used . T i -w e igh ted sequen ce s , 6 0 0 /2 0 (TR /TE ), w e re used , as we re tw o -echosequence s , 2 000 /2 0 , 9 0 , w h ich w ere p ro to n -den s ity -w e ig h te d andT2 -w eig hte d, re sp ec tive ly .

T he f irs t fiv e pa tie n ts h ad co ro na l a nd sa g itta l T i-w e igh ted im age sfo llowed by a T 2 -w e igh ted sequence in the p lane in w h ich th e les ionw as best v isua lized . The las t 1 6 pa tien ts had bo th co rona l and sag itta lT2 -w e ig h te d im ages an d T i-w e igh ted im ages on ly in th e p la ne inwh ich v is ua liza tion o f th e les io n w as op tim a l. T h is p ro to co l w as usedbecause the T2 -we igh ted im ages bes t de fined the jo in t su rface andthe reac tive in te rfa ce be tween the fragm en t and the fem ur.

Each M R scan w as e va lu a te d b y one ob se rve r w ith ou t kn ow ledgeo f th e a rth ro scop ic find ing s fo r fra gm en t s ign a l in te ns ity , a rticu la rca r tila ge de fec ts , an d ev ide nce o f ins tab ility a s lis ted in th e fo llow in gsec tion s . S ign a l in te ns ity w ith in th e fragm en t o n bo th T i- a nd T2-we igh ted im ages w as g rad ed by com paring th e fra gm en t s igna l w ithth e su rro u nd in g fem ora l m edu lla ry s pa ce by u s in g a g ra d ing sys temin w h ich -2 = m a rked ly d ec rea sed o r a bsen t s ig n a l, - i = m ild ly o rmodera te ly decreased s igna l, 0 = in ten s ity e qu a l to tha t o f fem ora lm arrow , i = m ode ra te ly in c re a sed s ig n a l, a nd +2 = marked lyin creased s ign a l eq ua l to tha t o f jo in t flu id .The T2 -w e igh ted im age s we re a lso e va lu a te d fo r (1 ) the p resen ceo r a bsen ce o f h igh s ig na l a t the fragm en t- fem ur in te r face (F igs . 1 B ,2B , 2C , and 3C ), (2 ) d is rup tion o f the subchond ra l bone p la te (F ig s .2B , 2C , 3C , 4B , and 4C ), (3 ) ad ja cen t fo ca l cy s tic a reas (F ig . 3D ), (4 )

d is p la ce d fragm en ts w ith in the jo in t (F ig . 4D ), a nd (5 ) d e fe c ts in thea rticu la r ca r ti la ge (F ig . 4C ).

T he M R fin d ing s w ere th e n com pa re d w ith the a rth ros cop ic fin d -ing s to se e if th e re we re d iffe re nce s be tw een the s ta b le , pa rtia llya tta ch ed , an d d is p la ce d le s io ns . O n the ba s is o f a rth ro scop ic f ind ing s ,th e le s ion s we re d iv ide d in to fou r g ro up s . O ne les io n w as s tab le (F ig .1) , th ree w ere pa rtia lly a tta ch ed w ith in tac t c a r tila ge (F ig . 2 ), 1 i w e repa rtia lly a ttac hed w ith ca rti la ge frac tu re s (F ig . 3 ), an d s ix had d is -p laced fra gm en ts (F ig . 4 ). P a rt ia lly a tta che d les ion s w ith in tac t c a rti-lag e w ere th o se th a t w e re ba llo ta b le w ith p rob in g , b u t the ca r ti la gewas in tac t a t a rth ros co py . In pa rtia lly a ttach ed les ion s w ith ca r tila gefrac tu res , th e frac tu re s w e re se en a t a rth ros cop y an d the le s io nswere ba llo tab le o r cou ld be e leva ted by prob ing . Loose fib rousgra nu la tion tis su e w as o ften fo un d in the b ase s o f th e pa r tia llya ttach ed fragm en ts th a t c ou ld be e leva ted . A s tab le le s io n was oneth a t d id n o t sh ow bon y un io n on p la in fi lm s bu t a t su rge ry sh owedno ca rt ilag e fra c tu re , no ca r tila ge so fte n in g , a nd wa s no t ba llo tab lew ith p ro bin g.

Resul tsIn tens ity o f s igna l w ith in the le s ions d id no t d iffe r be tw een

the s tab le o r tw o ca tego rie s o f pa rtia lly a tta ched les ions . O nT i -w e igh ted im ages, the le s ions had inhom ogeneous s igna lrang ing from g rades 0 to -2 (F ig . 36 ). F ragm en t appea rancefo r the s tab le o r pa rtia lly a tta ched les ions on T 2 -w e igh tedim ages w as m ore va riab le . Fou r le s ions w e re hom ogeneousw ith -2 absen t s igna l. T he rem a inde r had an inhom ogeneouspa tte rn w ith fo ca l a reas rang ing from +2 h igh s igna l to -2absen t s igna l w ith m a rked va ria tion be tw een the le s ions (F ig s .iB , 2C , and 3C ).

Les ions w ith d isp la ced fragm en ts had on ly bone de fec ts ,so no pa rtia lly a tta ched fragm en t cou ld be assessed fo rcen tra l s igna l o r h igh s igna l a t the ad jacen t bone in te rfa ce . A lls ix pa tien ts w ith d isp la ced fragm en ts had bony de fec ts fil le dw ith jo in t flu id tha t w as o f in te rm ed ia te s igna l on T i -w e igh tedim ages and o f h igh s igna l on T 2 -w e igh ted im ages (F ig s . 4Band 4C ).

A ll pa tien ts w ith pa rtia lly a ttached fragm en ts had a h igh -s igna l lin e a t the in te rfa ce be tween the le s ion and the fem u r

F ig . 1 .-S tab le o s teocho nd ritis d isse ca ns d i-ag no sed at su rge ry .

A, P reope ra tiv e p la in fi lm sh ow s la rge m ed ia lco nd yle le sio n.

B , Sag i t t a l M R im age , 20 00 /9 0 , show s h igh -s ign a l lin e ( a r r owheads ) ab ove frag me nt; th isresulted i n f a ls e - p o s it i v e M R d ia gn os is o f u ns ta -b le fra gm en t. Tw o yea rs a f te r d r illin g , les ionappea re d hea led on p la in film and M R ( no tshown) .


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F ig . 2 .-P art ia l ly a ttach ed o ste ocho nd rit is d is se cans w ith in ta c t c art ilag e .A , P la in f ilm sh ow s m ed ia l c on dy le d e fe c t w ith ce ntra l fra gm en t.B an d C , S ag it ta l (B ) and coro na l (C ) MR im ag es , 2 000 /9 0 . B on e-fra gm en t in te rfa ce shows h ig h s igna l ( a r r owheads ) , in dic atin g u ns ta ble fra gm en t.

S ig na l w ith in fragm en t is no nspec if ic , b e in g m os tly -2 absen t s ig na l b ut w ith lin ea r -1 an d + 2 s ign a l w ith in i t. S ub cho nd ra l bo ne p la te a pp ea rs d is ru pte d(ar rows) , a lth ou gh ca rtila ge w as in ta ct a t a rth ro sc op y.

A JR :15 5, S ep tem be r 1 990 MR OF OSTEOCHONDR IT IS D ISSECANS O F THE KNEE 55 1

F ig . 3 .-P ar tia ll y a tta ch ed o ste och on dritisd issecans w ith ca r tila ge fra ctu re .A, P la in film shows la te ra l c ond y le de fec t.B -D , H ig h s ign a l o n MR Im ages a t fragm en t-bone In te rfa ce an d cys t ind ica te fragm en t is

uns tab le . M R reve a ls tha t la rge p la in film d efec tis filled w ith fib ro us tis su e o r fib ro ca rtilag e. O nco ron a l MR im ag e , 6 00 /20 (B) , fra gm en t ha scen tra l h om og en eo us -1 s ig naL On co ro na l M Rimag e , 2000 /90 (C ), fragm en t ha s n on sp ec ificmixed - I low ( a r rows) and -2 absen t s ig na l. O nsag itta l M R im ag e , 20 00 /90 (0) , subchondra lp la te is d is rup ted ( a r row ) w ith ad ja cen t cy s t( a r r owhead) .


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., - . . : :- P, .-. :..4 . . .

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F ig . 4 .-O ste ocho nd rit is d iss ec ans w ith d is -p la ce d fr ag m en t.

A, P la in film shows bon y d efec t in m ed ia lfe mo ra l c on dy le ( a r row ) .

B-D , M R re ve a ls th a t sm a ll p la in f ilm d efe c tis ac tu a lly a la rg e su rfa ce ca v ity . O n co ron a l M Rim ag e, 60 0/2 0 (B) , de fe c t is fil le d w ith in te rm e-d ia te -s ign a l flu id . O n sag it ta l M R im age , 2 00 0 /90 (C ), de fec t is fi lled w ith h igh -s ign a l flu id . O nsag itta l M R im age , 2000 /90 (D) , d is plac ed frag -men t ( a r r ow ) is e m be dd ed in fa t pa d w ith over -l yi ng f lu id .

(F ig s . 2B , 2C , and 3C ). E ven the s tab le le s ion had a de fin iteh igh -s igna l lin e a t the fragm en t-fem u r in te rfa ce (F ig . 1 B ).

N ine o f the 20 pa tien ts w ith pa rtia lly a tta ched o r d isp la cedfragm en ts had round , c ys tlike a reas in the fem u r ad ja cen t tothe O CD (F ig . 3D ). These cys tic areas w e re o f in te rm ed ia tes igna l in tens ity on T i -w e igh ted im ages and o f very h igh s igna lin tens ity on T2 -we igh ted im ages. The s tab le le s ion d id no thave an ad jacen t c ys t.

T he subchond ra l bone p la te w as d is rup ted on both T i - an dT2-w e ig h te d im ages in a ll 2 i pa tien ts (F ig s . 2B , 3D , 4B , and4C ). Loose bod ies w e re found on M R im ag ing in a ll s ixpa tien ts w ith d isp la ced fragm en ts . These loose bod ies w e rev isua liz ed as low -s igna l fill in g de fec ts com p le te ly o r pa rtia llysu rrounded by h igh -s igna l jo in t flu id on T2 -w e igh ted im ages(F ig . 4D ). If the re we re m ultip le loose bod ies , it w as d ifficu ltto find a ll o f the loose bod ies on the M R scan . Co rre la tionw ith the p la in film s w as needed to con fiden tly iden tify seve ra lfragm en ts em bedded in the synov ium . Tw o loose bod ies w e reca rtila g inous and w e re seen on M R im ages bu t no t seen onthe p la in film s.

Discuss ionA lthough m any im ag ing m e thods have been used to s tudy

OCD fragm en ts , im ag ing o f la rge se rie s o f pa tien ts to de te r-

m ine le s ion s tab ility has been repo rted on ly fo r rad ionuc lideim ag ing [4 , 9 , 1 0] and M R im ag ing [1 0 ]. W ith rad ionuc lidescann ing , find ings be tw een stab le and uns tab le fragm en tsove rlap . R ad ionuc lide scann ing a lso p rov ides no ana tom icin fo rm ation on a rtic u la r su rfa ce de fo rm ity .

W e expec ted tha t M R im ag ing w ou ld be idea l fo r eva lua tiono f OCD because o f its non in vas ive na tu re , absence o f ion iz ingrad ia tion , exce llen t ana tom ic de ta il, and so ft- tis sue con tra s ta llow ing ca rtila ge v isua liz a tion . W e had hoped tha t, in add itionto de tec ting su rfa ce de fec ts , M R cou ld accu ra te ly d is tingu ishbe tween stab le and unstab le fragm en ts . O u r obse rva tion tha tone pa tien t w ith a s tab le le s ion had M R find ings s im ila r to theuns tab le le s ions w as d isappo in ting bu t cons is ten t w ith thelite ra tu re . M esga rzadeh e t a l. [1 0 ] found tha t M R im ag ingwas 92% sens it ive and 90% spec ific in sepa ra tin g n in e s tab lefrom i 2 loose le s ions . T hey m isd iagnosed one hea led le s ionas uns tab le us ing d is rup tion o f the ca rtila ge su rfa ce and thepresence o f a h ig h -s igna l line a s crite ria fo r les ion ins tab ility .

The m os t d ram atic ro le fo r MR im ag ing is in v isua liz in g thep resence and s ize o f a rticu la r cartila ge de fec ts and iden tifi-ca tion o f ca rtila g inous loose bod ies . T h is in fo rm a tion w asuse fu l in p reope ra tive p lann ing and in adv is ing the pa tien tabou t the poo re r p rognos is w ith a la rge ca rtila ge defec t.

B ecause o f ou r one fa ls e -pos itiv e d iagnos is o f le s ion in s ta-b ility , w e a re us ing the p resence o f a h igh -s igna l lin e benea th


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the le s ion as a sugges tive bu t no t abso lu te ind ica to r o f anuns tab le le s ion . A lthough our one fa lse -pos itive case d id no tme e t ou r a rth roscop ic c r ite r ia fo r an uns tab le le s ion , w e th in kbu t canno t p rove tha t the le s ion w as s til l uns tab le . A lthoughthe le s ion appeared s tab le a t su rge ry , it had an ove rly ingd im p le and the a rth roscop is t d r il le d the le s ion to inducehea ling . The les ion began hea ling im m ed ia te ly and w as com -p le te ly hea led in 2 yea rs . W e th in k tha t a lthough the le s ionw as s tab le to p rob ing , m ic roscop ic fragm en t m o tion occu rredunde r g rea te r fo rces gene ra ted by w e igh t bea ring . T h is pa -tien ts knee had been pa in fu l w ith ac tiv ity fo r 2 yea rs be fo rew e began ca ring fo r h im . The pa tien t w as fo llowed up fo r iyea r w ith a conse rva tive p rog ram inc lud ing 3 m on ths o f kneeb rac ing and the use o f c ru tches . T he pa tien t had knee pa inw ith am bu la tion th roughou t the conse rva tiv e m anagem en tpe r iod bu t ran w ithou t knee pa in w ith in 7 m on ths a fte rsurgery .

M esgarzadeh e t a l. [1 0 ] found th a t e ig h t o f the ir n in e sta b lele s ions had no h igh s igna l a t the fragm en t in te rfa ce . W e a lsono ted in a p rev ious s tudy [i 5 ] tha t the absence o f a h igh -s igna l line in ta la r OCD was a re liab le s ign of a hea led O CD .O n the bas is o f these tw o stud ie s , w e have been assum ingtha t pa tien ts w ith no h igh s igna l a t the in te rfa ce have hea ledle s ions . La rge se r ie s o f pa tien ts w ith M R exam ina tions andtrea ting pa tien ts conse rva tive ly un til b ony un ion occu rs w illbe needed to see if ab sence o f a h igh -s ig na l in te rface is are liab le s ign o f a s tab le le s ion .

The reason pa tien ts w ith s ta b le o r pa rtia lly a ttached les ion sand in ta c t ca rtila ge had appa ren tly d is rup ted ca rtila ge on M Rim ag ing in the p resence o f in ta c t ca rtila ge a t a rth roscopy isun known . Mesga rzadeh e t a l. [1 0 ] a lso no ted appa ren t ca rti-lage d iscon tinu ity on MR im ag ing in i i o f the ir u ns tab lele s ions , bu t on ly five had d is rup ted ca rtila ge a t su rge ry .P resum ab ly the ca rtila ge su ffe rs an in itia l in ju ry w ith e ithe rrepa ra tiv e tis sue o r o ld hem o rrhage pe rs is ting a t tha t s ite .W e canno t exp la in why th is tissue in the a rticu la r cartila geand subchond ra l bone p la te reg ion w ou ld have pe rs is ten ts igna l cha rac te r is tics resem bling flu id o r g ranu la tion tissue .

The h igh -s igna l in te rfa ce a t the junc tion be tween the frag -m en t and the fem u r is no t as puzz ling . H is to log ic s tud ie s a fte rM R im ag ing o f avascu la r necros is o f the fem o ra l head havefound tha t g ranu la tion tissue a t the m a rg in s o f the nec ro ticbone can pre sen t as a h igh -s igna l lin e [i 6 , 1 7]. In ag reem en tw ith these fem ora l head s tud ie s , w e noted a t su rge ry tha tpa rtia lly a tta ched fragm en ts o ften had fib rous g ranu la tiontissue in the base o f the de fec t.

F oca l cy s tic a reas benea th the fragm ents w e re seen on lyw ith uns tab le fra gm en ts . W e prev io us ly show ed tha t in ta la rO CD such cysts w ere seen on ly w ith uns tab le fragm en ts[i 5 ]. These cys ts w e re found to be cav itie s fil le d w ith g ranu -la tio n tiss ue [15 ]. F u rthe r s tudy o f pa tien ts w ith p roven s tab le

le s ions w ill be needed to p rove tha t cys tic a reas a re neve rseen in sta b le les ions .

In summ ary , M R im ag ing o f OCD p rov ides un ique in fo r-m a tion by de tec ting ca rtila g inous loose bod ies and a rtic u la rsu rface de fe cts . H igh s igna l a t the fra gm en t in te rla ce wasseen in a ll uns tab le les ion s bu t a lso in one questionab ly s ta b lele s io n . C ys tic le s io ns benea th th e fragm en ts we re seen on lyin uns tab le le s ions . O n the bas is o f these find ings , w e be lie vetha t M R im ag ing is usefu l in eva lua ting le s ion s tab ility anda rticu la r ca rtila ge de fec ts in pa tien ts w ith fem o ra l OCD .

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1 1 . Pa ille P . O uesn e l C , B aun in C , R ailh ac JJ . C om pu ted a rth rog ra ph y: its ro lein th e sc reen ing o f jo in t d ise ases in ped ia tric rad io lo gy . P ed ia tr R ad io !1988 ;18 :386 -390

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1 3 . Lu tte n C , Thom as W . NM R crite ria o f os te o chondrit is d isse cans o f th ekne e jo in t, the troch le a o f th e ta lu s, pa te lla a nd ca pitu lum o f th e h um e ru s:p re op era tiv e s itu a tio n an d postop e ra tiv e fo llow -up . E!ec t r omed ic a1 9 8 8; 5 6 : 1 1 8- 1 2 5

14 . S im s RE , G enan t HK . M agne tic reso na nce im ag ing o f jo in t d isea se . Rad io !d in N o rth Am 1 98 6;2 4( 2): 1 79 -1 88

15 . D e Sm et AA , F ishe r D R , B um ste in M l, G ra f B K , La ng e RH . Va lue o f MRim ag in g in s tag in g o steo ch on dra l les io ns o f the ta lus (o ste oc ho nd rit isd is secans ) : r es ul ts i n 1 4 p at ie nt s. A iR 1990 ;154 :555 -558

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osteochondritis dissecans, mr imaging

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