47 6 THE JOURNAL OF BONE AND JOINT SURGERY Carpal Instability* BY LEONARD K. RUBY, M.D.t. BOSTON. MASSACHUSETTS An Instructional Course Lecture, The American Academy ofOnthopaedic Surgeons Although the anatomy and function of the wrist have been studied since medieval times, th current em- phasis on this subject dates from th classic 1972 study by Linscheid et al.’9, which increased interest in trau- matic instability of the wrist and its pathomechanics. That study was based on the works of several authors, including Destot5, Navarro24, Gifford et al.9, and Fisk7. The present lecture describes the recent advances in the understanding of the structure and function of the wrist and summarizes the current thinking regarding the di- agnosis and treatment of the clinically important carpal instabilities. Bones Anatomy The carpus includes four sets of joints: the distal radio-ulnar joint, the radiocarpa joint. the mid-canpal joint, and the carpometacarpal joints. In this lecture, I will limit my discussion to the radiocarpal and mid- carpal joints. The bones of the carpus can be thought of as lying in two rows. The proximal row consists of te scaphoid, the lunate, and the tniquctrum. The pisiform is a sesamoid bone in the tendon of the flexor carpi ulnanis and as such, is not a functional part of the proximal row. The distal row i composed of the trapezium, the trape- zoid, the ca itate, and the hamate. The mid-carpal joint is the confluent articulation between the proximal and distal carpal rows. The scaphoid occupies a unique posi- tion, as it spans the mid-carpal joint and forms an osse- ous link between the proximal and distal rows’7. Ligaments Each bone is relatively tightly and securely bound to its neighbors by strong interosseous ligaments. The interosseous ligaments of the distal row seldom fail din- ically. The interosseous ligaments of the proximal row include the ligament between the scaphoid and the lu- nate (the scaph lunate interosseous ligament) and the *printed with permission of The American Academy of Ortho- paedic Surgeons. This article will appear in Instructional Course Lectures, Volume 45, The American Academy of Orthopaedic Sur- geons, Rosemont. Illinois, March 1996. tNew England Medical Center, 70 Washington Street. Boston, Massachusetts 02111. ligament between the tniquetrum and the lunate (the tniquetrolunate interosseous ligament). These ligaments are c-shaped: hey are attached to the dorsal, palmar, and proximal edges of each of the three bones of the proximal row. They are open dista ly into the mid-carpal joint, so that an anthrogram of a normal mid-canpal joint shows contrast medium between the three bones. The ligaments are thickened dorsally and palmarly and have a relatively thin membranous portion centrally (Figs. 1 and ). Recent studies have shown that the central por- tions are not nearly as strong as the dorsal and palmar portions and, therefore, may not be as important me- chanically. Mayfield et al.2’ and Logan et al.’9 measured the failure str ngth’ and stress-strain behavionis these ligaments in cadavenic specimens and reported that the scapholunate interosseous ligament failed at 232.6 ± 10.9 newtons (52.3 ± 2.5 pounds) and he tniquetro- lunate interosseous ligament, at 353.7 ± 69.2 newtons (79.5 ± 15.6 pounds). Furthermore, both of these liga- ments elongated by as much as 50 to 100 per cent of their original length before failure. In addition to the interosseous ligaments, the wrist con ains the dorsal and palmar capsular ligaments, which are thickenings of the wrist capsule. These liga- ments also have been well described by several authors, including Taleisnik32, Mayfield et al.si, and Berger and Landsmeeni. The dorsal capsular ligaments include the dorsal radiocanpal ligament and the dorsal intercarpal ligament (Fig. 3); the former may be especially impor- tant as an accessory stabilizer of the tniquetrolunate and radiocarpaljoints37.Taleisnik32 described the palmar cap- sular ligaments as c nsisting of the nadioscaphocap tate, the radiolunate, the radioscapholunate, the ulnolunate, and the ulnotriquetral ligaments. In addition, he de- scnibed the radioscaphocapitate and tniquetrocapitate ligaments as crossing the mid-carpal joint and, together, forming the so-called V. deltoid, or arcuate ligaments. The palmar ligaments recently were described again by Bergen and Landsmeen’, who suggested that the nadioscaphocapitate ligament inserts strongly into the scaphoid and weakly into the capitate. They renamed the radiolunate ligament, calling it the long nadiolu- nate ligament in order to distinguish it from the short nadiolunate ligament, which originates from the palman
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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 .)
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 -
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
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 .
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 .)
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
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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