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47 6 TH E JOURNA L O F BONE AND JO INT SU RG ERY

C arpa l In stab ility *

BY LEONARD K . RUBY , M .D .t . BO STON . M A SSACHU SETTS

An Ins tru ctio na l C ourse Lec ture, Th e Am erican A cadem y o fOn thopaedic Surgeons

A ltho ugh the ana tom y and fu nc tion of th e w rist

have been stud ied sin ce m ed iev al tim es, the cu rren t em -

p hasis o n th is sub jec t da te s from the cla ssic 19 72 study

by L insch eid et a l.’9 , w h ich inc rea sed in tere st in trau -

m atic in stab ility o f th e w ris t an d its pa thom ech an ics .

Tha t stu dy w as based on the w orks o f seve ral au th o rs ,

inc lud ing D esto t5 , N av a rro24 , G iffo rd et a l.9 , and F isk7 .

The p re sen t lec tu re desc rib es the recen t adv an ces in th e

un de rstand ing of the struc tu re an d fun ctio n of the w rist

and summ arizes the cu rren t th ink ing rega rd ing the d i-

agno sis and trea tm en t o f th e clin ica lly im portan t ca rpa l

in stab i l i t ies .

Bone s

Ana t omy

The carpu s inc lud es fou r se ts o f jo in ts : the d is tal

rad io -u lna r jo in t, th e rad iocarpa l jo in t. th e m id -canp al

jo in t, and the ca rpom etacarpa l jo in ts . In th is lec tu re,

I w ill lim it m y d iscus sion to the rad ioca rp al and m id-

carpa l jo in ts . T he bones o f th e ca rpus can be tho ugh t o f

a s ly in g in tw o row s . Th e prox im a l row cons ists o f the

scaph o id , the lun a te, an d the tn iquc trum . The p is ifo rm is

a sesam oid b one in th e tendon of th e flex o r ca rp i u lnan is

and , a s such , is n o t a fun ctio na l pa rt o f the p ro x im a l row .

The d is tal row is com posed of the trapez ium , th e trape -

zo id , the cap ita te , and the ham a te . T he m id -ca rp al jo in t

is th e confluen t a rticu la tion be tw een the p ro x im a l and

d istal ca rpa l row s. Th e scap ho id occup ies a un iq ue po si-

tion , as it span s the m id -ca rp a l jo in t and fo rm s an o sse -

ou s lin k be tw een th e p ro x im a l and d is tal row s’7 .

Ligaments

E ach bone is rela tive ly tigh tly an d secu re ly bo und

to its n eig hbo rs b y strong in te ro sseous lig am en ts . Th e

in te rosseou s ligam en ts o f the d ista l row se ldom fa il d in -

ically . T he in te ro sseous lig am en ts o f the p rox im a l row

inc lud e th e ligam en t b etw een the scaph o id an d the lu -

na te ( the scapho luna te in teros seo us lig am en t) and the

*pr in ted w ith p erm iss io n of Th e Am eric an A cad em y of O r tho -

paed ic Su rgeons . T his a rtic le w ill ap pea r in Ins truc tio nal C ourse

Lec tures , V o lum e 45 , T he Am eric an A cadem y of O rth opaed ic Su r-

g eon s, R osem ont. Il lino is, M a rch 1 996 .

tNew England M edical C enter , 750 W ashing ton S treet. B os ton ,

M assa chu set ts 0 21 11 .

lig am en t b etw een the tn iqu etrum and th e lun ate ( the

tn ique tro lun ate in te rosseou s ligam en t) . T hese ligam en ts

a re c -shaped : they a re attached to the do rsa l, p alm ar,

and p ro x im a l edg es o f each of the th ree b ones o f the

p ro x im a l row . T hey are o pen d istally in to the m id -ca rp a l

jo in t, so tha t an an th rog ram of a no rm a l m id -canpa l jo in t

show s co n tras t m ed ium be tw een the th ree b ones. T he

ligam en ts a re th ick ened dorsally and p alm arly and h ave

a re la tiv e ly th in m em branou s po rtio n cen tra lly (F ig s. 1

and 2 ). R ecen t stud ie s have sh ow n tha t th e cen tra l po r-

tion s a re n o t nea rly as s tron g as th e do rsa l and p alm ar

p ortio ns and , the re fo re, m ay no t b e as im portan t m e-

chan ica lly . M ay fie ld et a l.2 ’ and Logan e t a l.’9 m easu red

the failu re stren g th ’ and stre ss-strain behav io n is th ese

ligam en ts in cadaven ic sp ec im ens an d reported th at the

scapho luna te in te ro sseous lig am en t failed a t 2 32 .6 ±

10 .9 new to ns (52 .3 ± 2 .5 pounds) an d th e tn ique tro -

lun a te in te rosseou s ligam en t, a t 3 53 .7 ± 69 .2 n ew to ns

(7 9 .5 ± 15.6 pound s). F u rthe rm ore, bo th o f these liga -

m en ts e lo nga ted by as m uch as 5 0 to 10 0 pe r cen t o f

the ir o r ig ina l leng th be fo re fa ilu re .

In add ition to the in te rosseou s ligam en ts , th e w rist

con tain s the dorsa l and p alm ar capsu la r ligam en ts ,

w h ich a re th icken in gs o f th e w rist cap su le . T hese lig a -

m en ts also have been w e ll desc rib ed b y seve ra l au th o rs ,

inc lud ing Ta le isn ik3 2 , M ayfield e t al.s i, and B erg er an d

Land sm een i. T he d orsal capsu la r ligam en ts in c lu de the

dorsa l rad io canp al ligam en t and th e do rsa l in te rca rp al

ligam en t (F ig . 3 ) ; the fo rm er m ay b e especia lly im por-

tan t a s an accesso ry stab iliz er o f th e tn iqu etro lu na te and

rad io ca rpa ljo in ts37 .T ale isn ik 32 desc rib ed the p alm ar cap -

su la r lig am en ts a s co nsistin g of the n ad ioscapho cap ita te ,

the rad io lun a te , the rad ioscaph o lun ate , the u lno lu na te,

an d th e u lno triq ue tra l ligam en ts . In add itio n , he de -

scn ibed th e rad io scap hocap ita te and tn iqu etrocap ita te

ligam en ts a s cross ing th e m id -ca rp a l jo in t and , toge the r ,

fo rm in g the so -ca lled V . de lto id , o r a rcua te ligam en ts .

T he pa lm ar lig am en ts recen tly w ere desc rib ed aga in

by B ergen and Landsm een’, w ho sug gested tha t th e

nad ioscaph ocap itate ligam en t in se r ts stro ng ly in to th e

scap ho id and w eak ly in to th e cap ita te . T hey renam ed

the rad io lu na te ligam en t, callin g it th e long nad io lu -

na te ligam en t in o rde r to d istin gu ish it from the short

nad io lu na te ligam en t, w h ich o rig in a te s from th e p alm an



F io . 1

CAR I’A L IN STAB IL ITY 47 7

VOL . 77-A . NO . 3 . M AR (’ll 199 5

Cross- sec t ion o f th e pro x im al carpal row of a cadav eric w ris t. C = c ap ita te . R = rad ius . P = p isifo rm . S = scap hoid . L = lu na te . T = t r i que trum.

SL I = sc aph olu nate in tero sseous ligam ent. LT I = triquetrolunate in te ros seo us ligam en t. L RL = long rad io lu nate ligam en t. a nd is =

in te rlig am entous su lcu s. (R ep rin ted . w ith perm is sio n . from : B e rge r. R . A .. an d L andsm ee r. J. M . E .: The p alm ar rad io ca rpal ligam en ts: a s tud y

o fadul tand feta l hum an w ris tjo in ts.J . H and S urg .. 1 SA :85 1 . 1 99 0 .)

edg e of th e d ista l pa r t o f th e rad ius a t its lun ate face t

and inser ts in to th e pa lm ar p o le o f the lu na te (F ig . 4 ).

T he sh ort rad io luna te ligam en t had no t been desc ribed

p rev io usly . an d it shou ld no t be co nfu sed w ith the

rad ioscapho luna te lig am en t d esc r ibed by Ta lc isn ik ’-3 .

The space o f Po irie r, a m ech an ica lly w eak a rea o f th e

pa lm ar w rist capsu le be tw een the p rox im a l an d d ista l

ca rp al row s. is con tin uou s w ith th e lig am en tous su l-

cus be tw een th e rad io scap hocap ita te ligam en t and th e

lon g rad io lun ate ligam en t. S tres s-stra in te sting of p al-m ar rad ioca rp al ligam en ts in cadave ra sh ow ed tha t the

rad ioscapho cap ita te ligam en t fa iled at 1 51 ± 30 n ew -

ton s (33 .9 ± 6 .7 p ounds) and th at th e long rad io lun ate

ligam en t fa iled a t 1 07 .2 ± 14 .8 new ton s (24 .1 ± 3 .3

po und s); th e ligam en ts e lon ga ted app ro x im a te ly 3 0 pe r

cen t b efo re failu re” . The refo re . a s ind ica ted prev iou sly ,

the in te ros seo us ligam en ts o f th e p rox im a l row are

s tron ge r and m ore ela stic than any of th e cap su la r liga -

m cn ts tha t h ave been tested .

Tetidons

The m u scu lo tend inou s u n its tha t m ove th e h an d an d

w rist o r ig ina te a t the elb ow and in se rt on th e m e taca r-

pa ls . N o m usc le s a ttach to th e p rox im a l ca rp al row .

Th e prim ary tiex o rs a re th e flexo r ca rp i rad ia lis an d

the flex o r ca rp i u ln an is . T he prim ary cx tenso ns a re th e

ex tenso r ca rp i rad ia lis lo ngu s and the ex tenso r carp i

rad ialis b rev is . T h e prim ary rad ia l dev ia to r is the abd uc -

to r po llicis lon gus . and the p rim ary u lna r d ev ia to r is the

ex tenso r carp i u ln an is . B ecau se a ll o f the se tend on s in -

sen t on th e m etacarpa ls and becau se the ca rp om c tacan -

pa l jo in ts and the a rticu la tion s o f the d is tal row are

rela tive ly im m ob ile. as is the d is ta l row , the en tire p ro x -

im al row fun ctio ns as an in te rca la ted segm en t. In add i-

tio n , th e m oto rs o f the w rist a rc lo ca ted pe rip he ra lly . a s

fa r from the cen te r o f m otion of th e w rist (tha t is , the

F i ; . 2

D raw ing sh ow ing the dorsal v iew of th e carpal in te rosseou s liga -

men ts . SL = sc ap ho lu n ate lig a me nt. LT = triq uetro luna te ligam en t.

-F-F = t rap ezio tra pezo id lig am ent . CT = cap ito tra pezo id ligam en t. and

CH = c ap itoh am ate lig am ent . ( R eprin ted . w ith p erm is sion . f rom : A n .

K -N .: B erg er. R . A .: and C ooney . W . P .. Ill: B iom ech an ics of th e W rist

Jo in t. p . 13 . N ew Y ork . S pringe r. 19 91 .)



47 I.. K . RUBY

I’H E Jt)URNAL OF BONE N I) JO INT SURGERY

Ft( . 3

I ) rawit ig (if the dorsal capsu lar lig an ien ts . 1 ) R (’ = d ors al ra dio car -

PZ L l l ig ii iien t. E )l(’ = do rsal in te rca rpa l ligan ien t. C = cap ita te . S =

sc aph oid . 1 = t riq uetrum . R = rad ius . and 1. 1 = u ln a. (R ep rin ted . with

pe rn lissio n . from : i\ii, K -N .: B e rge r, R . A .: an d Cooney . W . P ., III :

B iom eeh anies of the W ris t Jo in t , p . 10 . N ew Y ork . S prin ge r. 1 991 .)

head of the cap ita te) as possib le . w h ich m ax im izes the ir

e ffect o n w rist n io tion . C onve rse ly . th e d ig ita l m o-

to rs are loca ted m ore cen tra lly (tha t is , c lo ser to the

head of the cap ita te ). w h ich d im in ishes the ir e ffect on

w rist m otio n .

K in ema t i c s

O ver the la st seven ty y ears . tw o th eo rie s - th e row

theory and the co lum n th eo ry - have been u sed to

exp lain th e k in em atic s o f th e w rist. A ccord in g to the

row th eo ry . a s d escr ibed ea rlie r . the hon es o f the w rist

can he thou gh t o f a s ly in g in tw o row s. the p rox im a l row

and the d ista l row . A ccord ing to the co lum n th eo ry . a s

o rig in ally sta ted b y N ava rro4 , the w rist is com posed of

th ree co lum ns: th e rad ia l co lum n (inc lud in g th e scaph-

o id . the trapez ium . and the trapezo id ) , th e cen tra l co l-

um n (inc lud in g the luna te an d the cap ita te ). an d the

u lna r co lum n (inc lud in g the tr ique trum and th e ha -

m ate ) . R ecen t stud ies have show n th at the row th eo rym ore clea rly accou n ts fo r the func tion of th e w ris t.

In a n orm al w rist, the to ta l a rc o f m otion av erages

l5 () deg rees: 70 d eg rees o f ex ten sion an d 80 degrees o f

f lex ion . A pprox im ate ly one -ha lf o f th is to ta l arc o f m o-

tio n occurs a t th e m id -carpa l jo in t and the o the r h alf

occurs at the rad io carpa l jo in t. F rom neu tra l to fu ll cx -

tensio n . app ro x im a te ly 66 pe r cen t o f th e m o tion occurs

at the rad iocarpa l jo in t an d 3 3 pe r cen t occu rs a t th e

m id -ca rp a l jo in t. F rom neu tra l to fu ll tiex ion . 6 0 pe r cen t

01 the m otio n occurs a t the m id -ca rp al jo in t an d 40 pe r

cen t occu rs at th e rad iocarpa l jo in t T he to tal am oun t

o f nad io -u lnan dev ia tion is 50 degrees. o f w h ich 20 de -

g rees is rad ia l dev iatio n and 30 degrees is u ln a r d ev ia-

tion ; 6 0 pe r cen t o f th is m o tion occu rs a t the m id -carpa l

jo in t. and 40 pe r cen t occu rs at the rad ioca rp a l jo in t2 9 .

N o t on ly do th e m id -ca rp al an d rad ioca rp al jo in ts

con tribu te d ifferen t am oun ts o f m otion to the to ta l arc ,

bu t they a lso allow m ov em en t in d iffe ren t d irec tions

w hen th e w ris t is m ov in g be tw een rad ia l and u lna r de -

v ia tion . A s the w ris t m ov es from rad ia l to u lna r dev ia -

tion , the en tire p ro x im a l row ro ta tes from a po sition of

flex io n to o ne of ex ten sion : a s th e w rist m oves from

uln ar to rad ia l dev ia tion , the en tire p ro x im a l row ro tate s

from ex tensio n back in to flex io n (F igs. 5 -A and 5 -B ).

A lthou gh the m echan ism by w h ich th is occu rs is no t

com p lete ly und ersto od , m ost au tho rs have agreed th at

it is a com b ina tion of the geom etry o f th e ca rpa l h on es,

the ir lig am en tou s re stra in ts . and the w rist m o to rs ac ting

th roug h the d istal ca rpa l row tha t cau ses th is con jo ined

syn ch ro nou s m o tion o f th e p rox im a l ca rpa l row . L in -

sche id and D obyns ’7 sugg es ted tha t, in rad ia l d ev iatio n ,

p re ssu re o n the d ista l po le o f the scap ho id b y th e trape -

z ium and trapezo id causes th e scapho id to f lex . T h is

flex io n fo rce is transm itted th ro ugh the scapho luna te

in te ro sseous ligam en t to th e lun ate and th rou gh the

tn iqu etro lu na te in terosseo us lig am en t to the tn iqu etrum ,

the reby caus ing th e en tire p ro x im a l row to flex . T he

Fu ; . 4

D raw ing o f the p alm ar c apsu la r lig aiiien ts. RSC = rad io-

sc aph ocap ita te lig am ent . LR L = lo ng rad io lu nate lig am ent . SRL =

sh ort ra d io lun ate lig am ent . U L = u lno lun ate lig am ent . UT = ulno-

t riquetral l igament . C = c ap ita te . L = lun ate , and S = scaphoid .

(R epr in ted . w ith pe rm ission . f rom : A n. K -N .: B erger . R . A .: and

Coon ey . W . P .. III: B iom echan ics of the W rist Jo in t , p . 6 . N ew Yo rk .

Sp r in g er . 1991 .)



F it ;. 5 -A FR i. 5 -B

CA RI’AL INSTA BIL ITY 47 9

O I.. 7 7-A . NO . 3 . N IARC II 1995

F igs . 5 -A and 5-B : Latera l rad iograph s of th e w rist o f th e au th or. C = c ap ita te . L = lu nate . and R = rad ius.

F ig . 5 -A : R adio graph m ad e w ith th e w r ist in rad ia l dev iat ion . N o te the fle x io n of the pro x im al row (the lu nate and scap hoid).

F ig . 5 -B : R adio graph m ade w ith the w ris t in u lna r dev iat ion . N ote the ex tens ion o fth e pro x im al row (th e lu na te an d scapho id) an d the d orsal

tra nsla tio n o f th e d ista l row (th e c ap ita te) (b la ck a rrow ). T he w h ite a rrow s s ign ify th e d irect ion of ro tat ion -ex ten sio n of the lu na te .

reve rse o ccu rs in u lna r dev ia tion , w ith th e scap ho id be -

in g ex tend ed th rou gh tens ion on th e scapho trapez ial

ligam en t. A lterna tive ly . W eh er4 p ro posed tha t th e h eli-

co ida l shape of th e triq ue tro ham a te a rticu la tion causes

th e d is tal OW to tran slate d o rsally du rin g u lna r dev ia -

tio n . the reh y pu tting pre ssu re on th e do rsal a sp ec t o f the

p rox imal OW and causin g it to ex ten d . In rad ia l dev ia -

tion . the d ista l row tran sla tes p alm arly , th ereby pu ttin g

pres su re o n the p alm ar asp ec t o f th e p rox im a l row and

caus ing it to flex .

W hateve r th e exac t m echan ism . the re no rm a lly is a

p red ictab le am oun t o f sm oo th , synchron ous m otion be -

tw een and w ith in the tw o ca rp al row s. Th ere is les s th an

9 degrees o f m otion be tw een th e cap itate . the trapezo id .

and th e h am ate in a ll a rc s o f m o tio n of the w rist. T h ereis 10 ± 3 degrees o f m otion b etw een the scap ho id and

the lu na te an d 14 ± 6 degrees o f m otio n be tw een the

tn ique trum and th e lun ate as th e w rist m ov es from fu ll

rad ia l dev ia tion to fu ll u lna r dev ia tion . T he re is 25 ± 15

degrees o f m o tio n b etw een the scap ho id an d th e luna te

and l ± 2 degrees o f m otio n b etw een the triq ue trum

and the lu na te a s th e w rist m oves from fu ll f lex ion to

fu ll ex tension . T hese d ata w ere de riv ed from cadave ric

stud ies , an d it is p ossib le tha t the actu al v alu es in v ivo

a re g rea te r (F igs . 6 -A and 6-B ). P a rtly o n the basis o f

th ese cadaven ic stud ies , w e agree w ith D esto t tha t the

p rox im al ca rp al row fu nc tion s as an in te rca la ted seg -

m cn t w ith v ariab le geom e try be tw een the d ista l row and

th e rad ius- tr ian gu la r f ib rocartilage com plex ’ .

F o rc e T ra ns m is sio n

Seve ra l recen t stu d ie s h ave d ea lt w ith the su b ject o f

quan tita tiv e as ses sm en t o f fo rce tran sm issio n th ro ug h

th e ca rp us 4 F o r techn ica l rea so ns, fo rce tran sm is-

sion h as been and con tin ues to be a d iff icu lt a rea to

stud y . N ev erthe le ss , w ith use o f load -ce lls , p re ssu re -

sensitive film . an d cadave ric sp ec im ens . d ata h av e been

gene ra ted th at desc rib e th e m agn itude an d locatio n o f

fo rce s at the rad ioca rp al jo in t in no rm a l cad av era and

in s im ula ted abno rm al co nd itio ns. P a lm er an d W erne r2 9

sh ow ed th at. in an in tac t cad av e ric w rist in the neu tra l

po sition , 8 2 pe r cen t o f the to ta l lo ad is carr ied by the

rad iu s and 18 pe r cen t. by the u lna . If the u lna r head is

re sec ted or the tr ian gu la r fib roca rtilage com plex is re-

m oved , th e ax ia l load tha t is bo rne by the u ln a is re-

du ced to 0 or 5 p e r cen t, re sp ec tive ly . These find in gs

w ere co nfirm ed by T rum b le e t aI .# {1 76} .ho fou nd tha t. in

in tac t spec im ens, 8 3 p er cen t o f the load w as bo rn e b y

the rad ius and 17 p e r cen t, b y the u lna . V iegas e t al.9 ’ .

w ho stu d ied the con tac t area s o f th e rad ius -tr ian gu la r

fib ro can tilage com plex in ax ia l-lo ad ed cad av eric w rists ,

fo und tha t w ith a ligh t load of tw en ty -th ree po und s

(ten k ilog ram s ). o n ly 20 pe r cen t o f the av a ilab le an tic -u la r su rface o f the rad iu s w as in con tac t w ith the bo nes

o f th e p rox im a l now . W ith a heav ie r load of fo rty -six

po und s (tw en ty -one k ilo g ram s) o r m ore . th is a rea in -

c rea sed to a m ax im um o f 40 pe r cen t and d id no t

inc rea se fu rth er ev en if the load w as doub led . T hey

con clu ded th a t the re no rm ally is a g rea t dea l o f incon -

g ru ity a t th e rad iocarpa l jo in t. T hey a lso foun d tha t 60

pe r cen t o f the rad ia l load norm a lly is bo rn e by the

scapho id face t an d 40 pe r cen t, by the luna te face t’

H on ii e t a l.’ and V iegas e t a l.5 ca lcu la ted th e lo ad

d is tribu tion a t the m id -ca rp al jo in t. H on ii e t a l. repo rted

tha t 31 pe r cen t o f th e to ta l ax ial load w as transm it-

ted th roug h th e scaph o id -trapez ium -trap ezo id jo in t; 19

pe r cen t, th roug h the scaph o lun ate jo in t; 29 pe r cen t.

th roug h th e cap ito lun ate jo in t: and 21 pe r cen t. th roug h

the tn iq ue tro ham a te jo in t. V iegas C t a l. repo rted sim ila r

da ta . T he areas tha t transm itted the h ighe r loads com e-

la ted w ell w ith th e reported d is tribu tion of os teo arth ro -

s is a t the rad ioca rpa l and m id-ca rpa l lev els” .

C arp al In sta bility

C arpa l in stab ility is d efined as carpa l m a la lign -

m en t. Th ere fo re , a ll w ris t d is locatio ns. such as a pe rilu -



R ad ia l d ev ia tio n #{ 247}

F i;. 6 -A

4k ” ) I.. K . R UB Y

IH E JOU RNA L O F BON E AN t) JO IN T SURGERY

na te d islo ca tion , and all w ris t sub luxa tio ns, such as a

scapho luna te d isso cia tion . a re exam ples o f ca rpa l in sta-

h ility . C arpa l in stab ility is no t a lw ay s synonym ous w ith

inc rea sed jo in t lax ity , as a m ala lig ned w rist m ay h e ve ry

stif f. I t also is im po rtan t to rea lize tha t n o t all unstab le

w rists are pa in fu l. T h e p re sen t d iscus sion w ill b e lim ited

to the d iag nos is an d trea tm en t o f som e of th e m o re

common and suh tle in te rca rp al in s tab ilities (th a t is .

sub luxat ions) .

Class if ication

There is n o un iv e rsa lly accep ted c la ssif ica tion o f

w rist in stab ility . In m y op in ion . the system th a t is based

Of l the row th eo ry of w rist m o tion is the m ost log ica l and

best f its th e k now n clin ica lly im portan t in stab ilities . A c -

co rd ing to L insche id et a l.’5 , m o st in stab ilitie s can be

thou gh t o f as m id -ca rp al m ala lignm en ts . T hese m id -

carpa l m a lalig nm en ts can h e c las sified eith er as do rsa l

in te rca lated -segm en t instab ility (comm only know n as

D IS I) o r a s v o la r in te rca lated -segm en t instab ility (com -

m on ly know n as V lS I). In dorsa l in te rca lated -segm en t

instab ility . th e p rox im al row (as de fin ed by th e long ax is

o f the lun ate ) is ex tend ed w ith respect to th e rad ius o n

late ral rad iog raph s. In vo la r in te rca la ted -segm en t insta -

h ility . the p rox im al row is f lex ed w ith re spec t to the

rad iu s on la tera l rad io g rap hs. T hese p atte rns can be su b-

d iv id ed fu rthe r in to no n-d issoc ia tive and d is soc ia tive

ca rpa l in stab ility4” . In no n-d issoc ia tive can pa l in stab ility ,

th e p rox im a l row is in tac t: in d isso c ia tiv e ca rp a l in stab il-

ity . a s o ccu rs in asso cia tio n w ith a frac tu re o f the scap h-

o id , th e p ro x im a l row is no t in tac t. T h us, th e re a re fo u r

basic pa tterns o f ca rpa l in stab ility tha t can h e seen on

pos teroan te r io r and late ral rad io g rap hs o f the w ris t: no n-

d issoc iativ e and d issoc iativ e dorsa l in te rca lated -segm en t

instab ility . and non -d is soc ia tive and d isso c iativ e vo la r

in te rca lated -segm en t in stab ility .

T h is system o f c las sifica tion can he exp an ded to in -

e lude rad ioca rpa l and ax ial m a la lignm en t a s w e ll. hu t

the se pa tte rn s a re les s comm on and a re beyond the

scop e of the p re sen t d iscussio n . A dd itio na l subd iv ision

based o n the tim e sin ce the in ju ry (tha t is . a s acu te o r

ch ron ic ) is p ossib le . D ynam ic in stab ilitie s tha t, b y de fi-

n ition , a re p ro du ced on ly by evo cativ e o r stre ss m aneu-

ve rs4 ’ can h e added to ex pand fu rthe r the system o f

c la ssifica tion . T he c lin ica l im po rtance o f d ynam ic in -

stab ilitie s is con trov ersia l and w ill no t be con side red

here.

C lin ica l D iagnosis

Sym ptom s o f w ris t in stab ility inc lud e p a in , w eak -

ness, g iv ing -w ay , and a so -called c lunk , snap , o r c lick

du rin g u se . P hys ica l ex am ina tion m ay revea l ten de rn ess

in an a rea in w hich syn ov itis h as d ev elo ped in re spo nse

to the o ve rlo ad ing of ar ticu la r su rfaces. In the acu te

situa tion . th e to rn ligam en ts m ay be d isc re te ly tend er:

how eve r. w ris t pa in o ften is d iff icu lt fo r the p atien t and

phy sic ian to lo ca lize. Th e re a re seve ral p rov oca tive m a-

F igs . 6 -A and 6 -B : D iagram s sh ow ing the rela tiv e m o tio n of se -

lec ted ca rpa l h one s w ith resp ect to on e an oth er an d to th e rad ius. Th e

num bers ind icate degre es of m o tio n .

F ig . 6 -A : R ela tiv e m otion as th e w rist m ov es from rad ia l to u lna r

dev ia tio n . N ote the m in im um am ount o f m o tion be tw een the bon es

of th e p rox im a l row .

n eu ve rs tha t can b e he lp fu l. W atson e t a l.5 d escr ibed a

m an euve r fo r th e d etec tion o f scap ho lu na te d issoc ia tion

in w h ich the exam in er m oves the w rist o f the pa tien t

from uln ar to rad ial dev ia tion w hile m ain tain ing don -

sally d irec ted p re ssu re ove r th e scap ho id tu be rc le to

p reven t flex ion of the scaph o id and to cause th e p ro x i-

m al p o le o f th e scap ho id to su b lux ate o ve r the do rsa l

edg e of th e rad ius. A po sitive re su lt w as de fined as a

ch aracte r is tic p ain fu l c lu nk on reduc tion of th e p rox i-

m al p o le o f th e scap ho id in to its rad ia l face t a s th e

exam in er m ov es the w rist o f the p atien t b ack in to u ln ar

d ev iatio n . R eagan et al.7 u sed a ba llo ttem en t tes t fo r th e

d etec tion o f tn ique tro luna te d isso c iatio n ; a po sitive re -

su lt w as d efined as the ab ility to d isp lace the tn ique trum

in a dorsa l-to -vo lar d irectio n w ith respect to the lun ate .

N on -d issoc ia tive vo la r in te rca la ted -segm en t instab ility ’ is con side red to be presen t if a cha rac te ris tic c lun k . sig -

n ify in g sudd en ex ten sion o r flex io n of the p rox im a l row ,

o ccu rs a s the exam in er m ov es the w rist o f th e pa tien t

from rad ial to u ln ar dev ia tion and hack w hile p lac ing

ax ia l com pression on the han d .

P la in rad io g rap hs can be u sed to sc reen fo r carpa l

in stab ility . R ou tine stud ies sh ou ld inc lude a true la tera l

rad iog raph as w ell a s poste roan ten io r rad iog raphs m ade

w ith the w rist in neu tra l, in rad ia l dev ia tion , and in u lna r

d ev iatio n . R ad iog raph s o f the con tra la te ra l w rist can be



FIG . 6 -B

Relativ e m otio n as the w r ist m oves f rom flex ion to ex ten sio n .

F IG . 7-A F o . 7 -B

CAR PA L INSTA B IL ITY 48 1

VOL . 7 7 .A , NO . 3 . MARCH 1995

m ade fo r com parison . In scap ho lu na te d isso cia tion (d is-

so cia tiv e dorsa l in te rca la ted -segm en t instab ility ) , the

la tera l rad iog raph show s an inc reased scapho luna te an -

g le o f m ore than 6 0 degrees, do rsa l angu la tio n o f the

lun ate and the tn ique trum , an d an in creased cap ito lu -

n ate ang le o f m ore than 15 d egrees. Th e posten oan ten io rrad iog naphs m ade w ith the w rist in n eu tra l and in u lna r

d ev iatio n show an inc rease in th e scapho luna te in te rva l

o f m ore than fo ur m illim e te rs com pared w ith the n on-

m a l side ; a so -ca lled ring sign ; and an inc reased ove rlap

o f the luna te and the cap ita te , w ith the b lu n t v o lan p o le

o f the lun ate p ro jectin g th roug h the head o f the cap ita te

(F igs . 7 -A and 7 -B ). T he ring sign is a rad iog raph ic phe -

nom enon in w hich the d ista l ha lf o f the scap ho id is seen

end-on becau se o f the abno rm ally ve rtica l pos ition o f

the bo ne . In th is co nd itio n , th ere also is dec reased carpa l

he igh t a s d ete rm ined by th e fix ed ra tio b etw een th e

len g th o f the th ird m e taca rpa l and the leng th o f a line

d raw n from the base o f th e th ird m e taca rpa l to the d ista l

pan t o f th e rad ius on the po ste roan ten ion rad iog raph

m ade w ith the w rist in the neu tral po sition ; th e n orm a l

rat io2#{176}s 0 .54 ± 0 .02 .

W hen a p atien t has tn iq ue tro luna te in stab ility (d is-

soc ia tive vo la r in tercala ted -segm en t instab ility ) , the

pos teroan ten io n rad iog raph show s a flex ed scaph o id

(tha t is , a po sitive rin g sign ) an d a flexed luna te , w ith

the sha rp do rsa l p o le o f the lu na te o ve rlapp ing the

cap itate (F ig . 8 -A ). In add ition , the re is a step -o ff a t

the tn ique tro lun a te jo in t, w ith th e triq ue trum pro x i-

m a l to the lu na te in u lnan dev ia tion and d ista l to it in

rad ia l dev ia tio n . Th e la te ra l rad iog raph show s a de -

c rea sed scap ho lu na te ang le o f les s than 3 0 degrees and

vo la r f lex ion of the lun ate and th e scapho id (F ig . 8 -B ).

In non -d issoc ia tive v o lan in te rca lated -segm en t in sta -

b ility , the po stenoan ten io n rad iog raph sh ow s flex ion of

the en tire p ro x im a l row (as ev idenced by th e sha rp

dorsa l po le o f th e lun ate ove rlap p ing the cap ita te ) b u t

no scapholuna te gap on tr ique tro luna te step -o ff (F ig .

9 -A ). Th e la te ra l rad iog raph show s a reduced or no n-

m a l scapho luna te ang le, flex io n o f the luna te , and a

dec reased cap ito lu na te ang le o f le ss than 15 d eg rees

(F ig . 9 -B ).

A n th ro gnaphy has b een the trad itio na l n ex t step af-ten stress rad iog raphy in th e d iagn osis o f ca rpa l in sta -

b ility becau se it is techn ica lly stra igh tfo rw ard and on ly

m in im ally in vasive and b ecause it can d em ons tra te de -

F igs . 7 -A and 7 -B : R ad iog rap hs o f a w rist in w hich the re is a sc aph olu na te d issociatio n .

F ig . 7 -A : Pos teroan terio r rad iog rap h sh ow ing a sc aph olu na te g ap o f m o re th an four m il lim ete rs, a p alm ar fle xed scapho id (S ) (the r ing s ign ),

a nd an ex tended lu nate (L ) and triq uetrum (T ). H = ham ate and R = rad ius.

F ig . 7 -B : La teral rad iog rap h show in g th e p alm ar flex ed scap hoid w ith do rsa l sub lux ation o f the pro x im al po le o f the scapho id and the

ex tended lu nate and triq uetrum .



F t.. 8 -A F ia . 8 -B

48 2 L . K . RUBY

TH E JO URNAL OF BONE AN I) JO IN T SUR GER Y

F ig s. 8 -A and 8-B : R adio graph s o f a w ris t in w hich there is a tr iqu etro lun ate d issociation . (‘= cap ita te . I I = h am ate . 1 . = lun ate . R = rad ius,

S = scapho id . an d T = t r iquetru rn .

F ig . 8 -A : Pos teroan ter io r rad iog rap h sh ow ing a flexed scapho id (th e ring sign ) and a flexed lun ate . w ith the sha rp do rsa l po le o f th e luna te

ov erla pp ing the c ap ita te . Th ere is a ste p-o ff at th e t riq uetro luna te jo in t. w ith the triq uetrum proxim al to the lu nate .

F ig . 8 -B : Latera l rad iograph show in g a d ecre ased scapho lun ate ang le and vola r fle x io n of the lu nate an d the scap ho id .

fec ts o f th e scaph o lun ate in te rosseou s ligam en t. the

tn iqu etro lu na te in te ro sseous lig am en t. and th e tn ian gu-

lam fib roca rtilage com plex reasonab ly w e lP ’. G reate r

sensitiv ity (th at is . a low er fa lse -n ega tive ra te) can b e

ach iev ed by in jec tion of the con tra st m ed ium in to th e

m id -carpa l jo in t . H ow ev e r, ar th rog raphy does no t re li-

ab ly dem onstrate th e d eg ree o r the exac t lo ca tion of

in te ro sseous -ligam en t dam age . sub tle ligam en tou s lax -

ity , the cond ition of the articu lan su rfaces, o r sm a ll d e -

g rees o f sy nov itis22 .

O the r no n-invasive m od alitie s tha t I occasio na lly

fin d usefu l inc lud e cin e rad iog raph y . s tre ss rad iog raphy .

bo ne -scann ing . and m agne tic reso nance im ag ing . A l-thou gh m agne tic re sonan ce im ag ing is an exce llen t tech -

n iqu e fo r the de tec tion of avascu la r nec ros is , it cu rren tly

is no t co st-e ffec tive fo r the d etec tion o f p artia l te ars o f

the ligam en ts o f th e w rist3 .

B ecause o f th e lim ita tion s o f a rth rog raph y an d

o the r non -in vasive d iagno stic m oda lities , ar th roscop y is

becom ing m ore p opu lar fo r th e ev alu atio n o f p atien ts

susp ected of hav in g ca rpa l in stab ility 94 . In m y exp e ri-

en ce , an th ro scopy often has led to a de fin itiv e d iag no-

sis and a rth ro sco p ica lly gu ided trea tm en t o ften has

been success fu l. W ith arth roscop y , the ex ten t and exact

lo ca tion of ligam en tou s in ju r ie s; th e cond ition o f the

articu lan su rface : the p re sence an d lo ca tion of syn ov itis ;

an d , in som e in stan ces, th e deg ree o f ca rp al d isp lace -m en t can be asce rta ined . Th e d isadvan tages o f th is tech -

F igs . 9 -A and 9-B : R ad iog rap hs of a w ris t in wh t c h the re is n on-d issoc iative vo lar in te rcala te d-segm en t ins tab ility . C = cap ita te . H = h ama t e .

L = luna te . R = ra d iu s. S = scap hoid . an d T = t r iquetrum.

F ig . 9 -A : Pos teroan ter io r ra d io graph show ing f lex ion of th e en tire pro x im al row . N o te th e lack of any triq uetro lu na te step -of f or

sc ap holuna te g ap .

F ig . 9 -B : L ate ral rad iog rap h show in g the dec rea sed sc aph olu nate an g le . Th e app earanc e is the sam e a s th at of d is soc iative vo lar

in terc ala ted -segm ent insta b il ity b ecause the tr iqu etrum is d ifficu l t to v isua liz e .



FI1 . 1 0

CARPAL INSTABILITY 48 3

VOL . 77.A , N O . 3 . M AR C H 1995

n iq ue inc lud e a steep lea rn in g cu rv e, an inc rea sed risk

o f ne rv e and tendon dam age , an d in creased exp en se .

T reatm en t o f Selected C ar pa l I ns ta bilit ie s

D issoc ia tive D orsa l In terca la ted-Segm ent In stab ility :

Scapho luna te D issoc ia tio n

A patien t w ho h as an acu te com ple te scap ho lu na te

d is soc ia tion often has a h isto ry o f a d onsif lex ion in ju ry

a fte r a fa ll w ith imm edia te p ain an d ten de rn es s at the

scap ho lu na te in te rva l. P la in rad io g rap hs sh ow the ch ar-

ac ten istic ch an ges n o ted prev ious ly : a scap ho lu na te gap

of m ore th an four m illim e te rs , p alm am flex ion o f th e

scap ho id w ith d orsal su b lu xa tion of the p rox im al p o le ,

an d an ex tend ed lu na te and tn ique trum (F igs. 7 -A and

7-B ). If the re still is u ncerta in ty as to the d iag nos is ,

ar th rog raphy o r a rth rosco py , on b o th , can be p erfo rm ed .

F or an acu te in ju ry (o ne tha t occu rred le ss th an s ix

w eeks p rev ious ly ) w ith a pa rtia l te ar o f th e scap ho lu -

na te in te rosseou s ligam en t, c lo sed reduc tion an d an -

th ro sco p ica lly and rad iog raph ica lly gu ided p inn ing can

b e pe rfo rm ed . C losed red uc tion is pe rfo rm ed w ith the

pa tien t und er ax illa ry b lock or gene ra l anesthesia by

firs t tran slatin g the cap ita te (and d istal row ) vo lan ly

w ith re spec t to th e luna te and stab ilizin g the cap ito lu -

n ate jo in t w ith a sm oo th 0 .062 -in ch (0 .15 7-cen tim ete r)

K irschn e r w ire . T he scaph o lun ate gap then is c losed

b y d irec t v o la rly d irected thum b pressu re o n the p rox i-

m al po le o f the scap ho id an d stab ilized e ith e r w ith

m ultip le 0 .0 45-inch (0 .1 14-cen tim e ter) K irschn er w ire s

ac ro ss the scap ho lu na te in te rva l o r w ith o ne 0 .06 2-inch

(0 .157 -cen tim e te r) w ire p laced across th e scaph o lun ate

jo in t and an o the r ac ros s th e scap hocap ita te jo in t (F ig .

1 0 ). T he w ires a re cu t o ff un de r th e sk in and le ft in p lace

fo r eig h t to ten w eeks w hile th e hand an d w rist a resu pp orted in a be low -th e-e lbow cast th at ex tends from

the m e tacarpo pha langea l jo in ts to d is tal to the e lbow .

A fte r rem ova l o f the w ire s , ran ge -o f-m o tion and w ris t-

s treng th en ing exe rc ise s are begun , an d th e w rist is

p ro tec ted w ith a rem ovab le sp lin t un til th ree to fou r

m on ths a f ter the ope ratio n .

F o r com ple te in ju rie s o f the scapho luna te in tenos-

seou s ligam en t o r m ore ch ro n ic con d ition s, o pen red uc -

tion an d fo rm a l ligam en tous repa ir, reco nstruc tion , o r

even an th ro desis u sua lly is n ecessa ry because red uc tion

an d ad eq ua te fix atio n canno t b e ach iev ed w ith clo sed

m eans9 ’5 . A do rsa l ap pro ach is used fo r v isua liza tion of

the tea r o f th e scapho luna te in terosseo us lig am en t, the

d isp laced prox im a l p o le o f the scaph o id , th e ex ten ded

luna te , and the dorsa lly d isp laced prox im a l head of the

cap itate (F ig . 11 . A ). K irsch ne r w ires a re p laced in th e

scap ho id and luna te an d used as joysticks to a id in m e-

duc tion . T he lu na te facet o f the scaph o id is clea red of

scar tissue , an d a troug h is created . D rill-ho le s a re

p laced in th is tro ug h , an d h eavy non-abso rbab le su tu res

are p laced in the ligam en tou s rem nan t tha t is attached

to th e lun a te (F ig . 1 1 . B an d C ). The su tu re s a re passed

th roug h the d rill-h o le s in the scapho id (F ig . 11 , D ).T he

Po ste roan te rio r ra d io graph m ad e af ter o pen reduc tio n an d in-

tern al fix atio n of a scapho lun ate d is soc iation (do rsal in tercala ted -

segm ent ins tab ility ). T he cap ito lu nate w ire w as p laced first. a nd then

the sc ap holuna te and scap hocap ita te w ires w ere p la ced .

d isso c iatio n is red uced and stab iliz ed w ith 0 .0 62-inch

( 0 .157 -cen tim e te r) K irs ch ne r w ire s a s descr ibed p re -

v io usly , and th e su tu res a re tied (F ig . 11 , E an d F) . T he

ad jacen t do rsa l capsu le o f the w rist can be im bn icated

to re in fo rce the p rim ary repa ir . T he po stop era tive ca re

is the sam e as tha t fo r the acu te in ju ry .If the d isso cia tion is irred uc ib le , o steoa rth ro sis a l-

ready h as occu rred , o r so ft-tissu e repa ir has fa iled , I

p refe r to pe rfo rm a to ta l m id -ca rp al o r a com ple te w rist

ar th rodesis . T h is is a con tro ve rsia l area, and m any au -

tho rs h av e recomm ended a m ore lim ited a rth rod es is ,

such as a scap ho id -trap ezium -trapezo id an th ro desis fo r

ch ro n ic in stab ility w itho u t o steoa rth ros is o r a cap itate -

ham a te- tn iq ue tnum -lu na te (fou r-co rne r) a rth nod esis and

scap ho id ex cis ion if osteo arth rosis is p re sen t4 3 . S cap ho lu -

na te , cap ito lun ate , and scap hocap ita te an th rodeses and

cap itate -ham a te- tn iq ue trum -lu na te ar th rodeses w itho u t

ex cis ion of th e scapho id a lso have been u sed fo r the

trea tm en t o f ch ron ic ins tab ility”39 . M y expe rien ce and a

ca refu l rev iew of th e lite ra tu re bo th have dem onstrated

h igh ra te s o f com p lica tio ns and unpred ic tab le re su lts

af te r all o f th ese pa rtial ar th rod eses.

D isso cia tive V ola r In terca la ted -S egm en t In stab ility :

T riqu etro luna te D isso c ia tion

A patien t w ho has an acu te tn ique tno luna te d is soc ia-

tio n o ften h as a h isto ry o f a no tatio na l in ju ry o f the w rist,

comm only as the re su lt o f ho ld ing a pow er d rill w hen th e

d rill b it ha s jamm ed . T he p atien t has pa in in the w ris t on



A5.

,/I

1

C

I

1

.. F

N

, , , t .T )

E1 .

F N .

FIG . 11

TH E JOURNA L O F BON E AN I) JO IN T SU RGERY

48 4 I. . K . R UB Y

B

D raw ing s show in g th e repa ir o f a sc ap holuna te in tero sseous l igam ent w ith ad junc t c apsu la r repa ir. A, T he tea r in th e sc aph olu na te

in te rosseous lig am ent (SL IL ) is v isual ized th rou gh a dorsal ap pro ach (L = l u n a t e . R = rad ius . a nd S = scaphoid) . B. H orizon tal m a ttr ess

su ture s of 0 non -ab sorbab le m ate ria l a re p lac ed in th e lig am ent . C. A trou gh is crea ted a lon g the lu nate fa cet of the scapho id . a nd d ril l-ho les

are p lac ed from th e scap ho id w aist to the tro ugh . D. Ke ith n eed les are used to pas s the su ture s th ro ug h the d rill -ho les. E an d F ,T he scap hoid .

lu nate , a nd c ap ita te are reduced an d p inn ed . af ter w hich th e su tures are tie d . (M od ifie d , w ith p erm is sion . from : L av ern ia . C . J.; C ohen , M . S .;

an d liile isn ik .J .:T reatm ent ofscap holuna te d isso cia tio n b y lig am entou s repa ir an d c ap su lo de sis.J. H and S urg .. 1 7A : 3 55 . 1 99 2 .)



FIG . 12 -A FIG . 12-B

F igs . 12 -A and 12 -B : R adio graphs of a m alun ite d fra ctu re of the d ista l par t o f the rad iu s w ith secon dary n on-d is soc iative do rsal

in terc ala ted -segm ent ins tab ility .

F ig . I 2-A : Pos teroan terio r rad iog rap h . N ote the d ors ifle xed pos itio n of the en tire prox im al row .

F ig . 1 2-B : L ate ral ra d io graph .

C AR PA L INSTA B IL ITY 48 5

\‘O I.. 7 7-A . NO . 3 . M ARC h 1995

th e u lna r s ide . e spec ially a t th e tn iqu etro lun a te jo in t.

T he exam ine r m ust he ca refu l to d istin gu ish th is

in ju ry from in ju rie s o f the tr ian gu la r f ib rocartilage com -

p lex . w h ich usua lly cause tend erness in the in te rva l b e -

tw een the ex ten so r ca rp i u lnan is and the flexo r ca rp i

u ln an is ju st d is ta l to th e u ln a r head . T he re su lt o f a

h allo ttem en t te st m ay be po sitive . as d esc r ibed pre-

v ious ly . The d iag nos is is con firm ed by th e p re sence o f a

step -o ff a t th e tn iqu etro lu na te in te rv al o n the po ste ro -

an te r io r rad io g rap h . A rth rosco p ic co nfirm a tion of th e

tea r m ay he necessa ry . If th ere is no vo la r in s tab ility

( ind ica ting on ly a p a rtia l tea r), pe rcu tan eo us p in n ing

gu id ed by arth roscop y or rad io g rap hy , o r bo th , is recom -

m ended . If vo la r in stab ility has deve lop ed or the de -

fo rm ity is ch ron ic h u t still redu c ib le , open repa ir o f thetr ique tro lun ate ligam en t com b ined w ith do rsa l capsu lo -

d es is can h e p erfo rm ed in a m anne r sim ilar to tha t de -

scn ihed fo r do rsa l in s tab ility . It is im portan t to realize

th at. in th is in stance , the go al o f capsu lod esis is to p re -

v en t excessive flex ion of the p ro x im a l row , pa rticu la rly

b y im bn ica tion of the d orsal rad io tn iq ue tra l ligam en t. I t

a lso m ay he he lp fu l to im brica te the space o f Po in ier o n

th e p alm ar side to re in fo rce the d orsa l rep air’4 . I redu ce

and p in the cap ito lun a te jo in t be fo re ty ing the capsu la r

su tu res : th e use o f su tu re ancho rs can fac ilitate th is m e-

p air . I p refe r to m ak e the d orsal exp osu re f irs t, p lace the

su tu res , an d red uce an d p in the w rist. I then p erfo rm the

an te r io r ap proach and clo se the space o f Po ir ier .

I f so f t- tissu e repa ir has fa iled o r osteoan th ro sis

is p resent. m id -ca rp al an th rodesis is the trea tm en t o f

cho ice . A lth ough tn iq ue tro luna te ar th rodesis seem s lo g -

ica l. h igh ra te s o f fa ilu re and of com plicatio ns h av e been

reported ’4 . and I n o lon ge r recomm end th is p rocedu re .

It a lso has b een no ted 4 tha t sym ptom a tic tn iq ue tro lu -

n ate instab ility o ften is accom pan ied by u lna r-h ead

abu tm en t. Th ere fo re . u ln ar recessio n osteo tom y o ften

is ind ica ted . If the re is no vo la r in te rca lated -segm en t

in stab ility . I p re fer to treat ch ron ic. com ple te. sym ptom -

atic , ir red uc ib le tn iq ue tro luna te team s w ith u lna r m eces-

sion os teo tom y alo ne , especia lly if the re is po sitive o r

neu tral u ln a r va riance .

Non-D issoc ia tive V olar In terca la ted-Segm ent Insta b ility

T his cond ition is a lm os t alw ays a ch ro n ic p rob lem

tha t beg in s insid io usly ; usu ally . it is a ssoc ia ted w ith gen -

em alized ligam en tou s lax ity . I t is d iag nosed on th e basis

o f a ch a rac ter is tic c lun k on ax ia l com p ression of the

w rist in rad ia l and u ln am dev ia tio n an d on the b asis o f

the signs o n p la in rad io gm aph s desc rib ed p rev io usly .

A n th rogm aphy and a rthno scopy ty p ically revea l no rm a l

find ing s. A s o steoa rth ros is has no t been show n to de -

ve lop as a re su lt o f th is in stab ility , an d b ecause the con -

d ition m ay rep re sen t a system ic p rob lem , n on -op era tivetrea tm en t co nsistin g o f fo rea rm -streng then ing exe rc is es

an d in te rm itten t sp lin ting sho u ld b e tried firs t’ If th is

trea tm en t fa ils , an te r io r and poste rio r cap su la r im bn ica -

tion an d tem porary m id -ca rp al p inn in g can be p er-

fo rm ed in a m anne r sim ilar to the techn ique used fo r

tn iqu etro lu na te d is soc ia tion . If th is p rocedure fails to

re lieve sym ptom s. m id -ca rpa l an th rodesis is an op tion .

Seconda ry N on-D issoc ia tive D orsa l

In terca la ted -S egm en t Insta b ility

This pa tte rn o f ins tab ility h as b een reco gn ized w ith

inc rea sing frequency since it w as firs t d escr ibed by

Ta le isn ik and W atson in 19 84 . It is no t a p rim ary d iso r-

den o f the w rist; ra th er , it is an adap tiv e po stu re o f

p rox im al-now ex ten sion second ary to dorsa l ang u la tion

of a m a lun ited frac tu re o f the d ista l pan t o f th e rad iu s

(F igs. 12 -A and 12-B ). If th e ins tab ility is sym ptom atic ,

do rsa l o pen in g -w edg e connectiv e osteo tom y of the m a-

d ius sho u ld be cura tive .

Summa ry

A grea t d eal o f p rog re ss has been m ade in recen t

years w ith re spec t to und erstand in g the no rm al and



48 6 L . K . RU BY

TH E JOURNAL . OF BONE AND JO INT SU RGERY

pa tho lo g ica l ana tom y of the w rist. N one the le ss . ou r w ith a critic al rev iew o f the standa rd rad iog raph s. sup -

know led ge is incom p lete . so them e still is room for d i- p lem en ted by add itiona l stu d ie s a s in d icated , a llow the

vem sity o f op in ion rega rd ing the d iag nos is and treatm en t astu te c lin ician to id en tify sp ec if ic pa tte rn s o f in stab ility

o f m ost o f th e p re sen tly recog n ized w rist in stab ilitie s . and to fo rm ula te an e ffec tiv e treatm en t p ro g ram for the

A care fu l h is to ry and phy sica l exam in atio n com bin ed pa tien t.

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CARPAL INSTA B IL ITY 48 7

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Vol. . 77-A . NO . 3 . MAR CE l 9 95