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8/19/2019 Survivorship Analysis of Cemented Total Condylar Knee Arthroplasty. a Long-term Follow-up Report on 348 Cases
http://slidepdf.com/reader/full/survivorship-analysis-of-cemented-total-condylar-knee-arthroplasty-a-long-term 1/4
T he J ou rna l o f A r t h rop l as t y V o l 11 N o 1 1996
S u r v i v o r s h i p n a l y s is o f C e m e n t e d T o ta l
C o n d y la r K n e e r t h r o p l a s ty
A L o n g te r m F o l l o w u p R e p o r t o n 3 4 8 C a se s
A d e l N a f e i , M D , O l e K r i s t e n s e n , M D , H a r a ld M o u s t g a a r d K n u d s e n , M D ,
I v a n H v i d , M D , P h D , a n d J o r n J e n s e n , M D
A b s t r a c t S u rv iv o r sh ip an a ly s i s w as u sed i n t h e ev a lu a t i o n o f 3 4 8 co n secu t iv e p r i -
m a r y t o t a l c o n d y l a r k n e e a r t h r o p l a s t i e s ( t o t a l k n e e a r t h r o p l a s t i e s ) p e r f o r m e d o n
2 5 3 p a t ie n t s i n a 2 7 - m o n t h p e r io d , w i t h a m a x i m u m f o l l o w - u p p e ri o d o f 1 2 y e a r s .
T h e d i ag n o s i s w as o s t eo a r th ro s i s i n 1 8 4 cases an d rh e u m ato id a r th r i t is i n 1 6 4 cases .
T en p a t i en t s (1 0 t o t a l k n ee a r th ro p l as t i e s ) w ere l o s t t o fo l l o w -u p ev a lu a t i o n . T h e
en d p o in t w as d e f in ed a s p ro s th es i s n o t in s i tu T h e v a r i ab l e s co n s id e red w ere ag e ,
sex , b o d y 1 T lass n d ex , an d d i ag n o si s . T h e o v e ra l l cu m u la t i v e su rv iv a l r a t e w as 9 2 .
T h e su rv iv a l r a t e o f t h e o s t eo a r th ro s i s g ro u p w a s s ig n if i can t ly h ig h e r (9 7 ) t h a n
th a t o f t h e rh e u m ato id a r th r i t i s g ro u p (8 7 ) . N o n e o f t h e o th e r v a r i ab l e s a f f ec t ed
surv ival ra te s ign if ican t ly . K e y w o r d s k n ee a r th ro p l as ty , k n ee p ro s th es i s , l o n g -
t e rm re su l ts , su rv iv o r sh ip an a ly s is , t o t a l co n d y la r k n ee .
T h e p r o s t h e s i s u s e d i n t h i s s t u d y i s a m o d i f i c a t i o n
( 5 ° p o s t e r i o r s l o p e o f t h e t i b i a l c o m p o n e n t ) o f t h e
o r i g in a l I n s a l l - B u r s t e i n p r o s t he s i s , w h i c h i s o f t h e
s e m i c o n s t r a i n e d , c r u d a t e l i g a m e m - s a c r i f i c i n g , c e -
m e n t e d t y p e w i t h o u t m e t a l b a ck i ng . S i n ce 1 97 9 t h e
p r o s th e s i s h a s b e e n u s e d i n o u r d e p a r t m e n t w h e n
t o t a l k n e e r e s u r f a c i n g a r t h r o p l a s t y w a s i n d i c a te d .
S e v e r a l a u t h o r s h a v e r e p o r t e d l o n g - t e r m s u r v i v a l
a n a l y s i s of t o t a l k n e e a r t h r o p l a s t y w i t h d i f f e re n t p r o s -
t h e t i c d e s i g ns . 1 4 F e w a u t h o r s h a v e r e p o r t e d l o n g -
t e r m s u r v i v a l a n a ly s i s o f t h i s d e si g n , a n d t h e n o n l y a s
s m a l l e r s u b g r o u p s o f l a r g e r h e t e r o g e n o u s s e r ie s . 4-6
T h i s s t u d y a i m e d t o e v a l u a t e t h e s u r v i v a l ra t e o f
a f a ir l y l a r ge c o n s e c u t i v e s e r i e s of t h e a b o v e - m e n -
t i o n e d p r o s t h e t i c d e s i gn , p e r f o r m e d a s a p r i m a r y
i n t e r v e n t i o n i n a s i ng l e c e n te r , a n d t o e v a l u a t e
s o m e o f t h e f a c t o r s t h a t m i g h t i n f l u e n c e t h e l o n g -
t e r m s u r v i v a l ra t e o f t h e p r o s t h e s e s .
From the Department of Orthopedic Surgery A arhu s University
Hospitals Aarhus Denmark.
Reprint requests: Adel Nafei MD Heriuf Trollesgade 7C st.
DK-8200 Aarhus N Denmark.
a t e r i a l s a n d e t h o d s
D u r i n g t h e p e r i o d O c t o b e r 1 9 7 9 t h r o u g h D e c e m -
b e r 1 9 8 2 , 3 4 8 c o n s e c u t i v e p r i m a r y t o t a l c o n d y l a r
k n e e a r t h ro p l a s ti e s ( TK A s ) w e r e p e r f o r m e d o n 2 5 3
p a t i e n t s . T h e d i a g n o s is w a s o s t e o a r t h r o s i s ( O A ) i n
1 8 4 ca s e s a n d r h e u m a t o i d a r t h r it i s ( R A ) in 1 6 4
c a s es . I n th e O A g r o u p , t h e r e w e r e 3 2 m e n ( 3 6
T IC A s) a n d 1 1 5 w o m e n ( 1 4 8 T K A s ) . I n t h e R A
g r o u p , t h e r e w e r e 2 1 m e n ( 3 3 T IC A s) a n d 8 5 w o m e n
( 1 3 1 T I C A s ) . M e d i a n a g e a t s u r g e r y w a s 7 0 y e a r s
( q u a rt i le s , 6 4 a n d 7 3 y e a r s ) in t h e O A g r o u p a n d 6 1
y e a r s ( q u a rt i le s , 5 0 a n d 6 8 y e a r s ) i n th e R A g r o u p .
T e n p a t i e n t s ( 1 0 TIC A s) w e r e l o s t t o f o l l o w - u p e v a l u -
a t i o n ( 5 T IC A s i n e a c h g r o u p ) . T h e i n d i c a t i o n f o r
k n e e a r t h r o p l a s t y in o u r d e p a r t m e n t i s c h r o n i c j o i n t
p a i n , d u e t o a d v a n c e d d e g e n e r a t i v e c h a n g e s i n v o l v -
i ng m o r e t h a n o n e j oi n t c o m p a r t m e n t .
T h e o p e r a t i n g t h e a t e r w a s e q u i p p e d w i t h l a m i -
n a r a ir f lo w . F i r s t - g e n e r a t i o n i n s t r u m e n t a t i o n w a s
u s e d f o r p r o s t h e s i s i m p l a n t a t i o n . 9 A l l s iz e s o f t h e
i m p l a n t w e r e a v a i l a b l e f o r u t i l iz a t i o n i n t h e p e r i o d
i n q u e s t i o n . W e r e s u r f a c e d t h e p a t e l l a i n a l l c a s e s .
8/19/2019 Survivorship Analysis of Cemented Total Condylar Knee Arthroplasty. a Long-term Follow-up Report on 348 Cases
http://slidepdf.com/reader/full/survivorship-analysis-of-cemented-total-condylar-knee-arthroplasty-a-long-term 2/4
8 T he J ou rna l o f A r t h rop l as t y Vo l 11 N o 1 J anu a ry 1996
T h e p ro s t h e t i c c o m p o n e n t s w e r e c e m e n t e d i n a ll
c a se s . A l l p a t i e n t s w e r e o p e r a t e d b y o r u n d e r
s u p e r v i s i o n o f t h e s a m e s e n i o r s u r g e o n . T h r e e
o t h e r s u r g e o n s w e r e i n v o l v e d . O p e r a t i v e t e c h n i c a l
g o a l s w e r e t o a c h i e v e a t i b i o f e m o r a l a l i g n m e n t
b e t w e e n 3 ° a n d 1 0 ° o f v al g u s , a n e u t r a l p o s i t i o n o f
t h e p r o s t h e t i c c o m p o n e n t s ( t il t < 5 °) , a r a n g e o f
m o t i o n g r e a t e r t h a n 9 5 ° , a n d a s ta b l e k n e e ( a m a x -
i m u m o f 5 ° i n s t a b i l i ty o n f u ll e x t e n s i o n ) .
P a t i e n ts w e r e e x a m i n e d c l in i c al l y a n d r a d i o g r a p h i -
c a l l y p r i o r t o s u r g e r y , i m m e d i a t e l y a f t e r s u r g e lT , 12
w e e k s a f t e r s u r g e ry , a n d a t o n e - y e a r i n t e r v a ls . T h e
k n e e r a t i n g s c o r e f r o m t h e H o s p i t a l f o r S p e c i a l
S u r ge r y ~0 w a s u s e d i n t h e e v a l u a t i o n s . T i b i o f e m o r a l
a l i g n m e n t b e f o r e a n d a f t er s u r g e r y a n d p o s i t i o n i n g
o f th e p r o s t h e t ic t i b i al c o m p o n e n t s a f te r s u r g e r y
w e r e a n a l y z e d in b o t h d i a g n o s t i c g r o u p s ( T a b le i ) .
F a i l u r e w a s d e f i n e d a s a p r o s t h e s i s w e r e a re v i -
s i o n o p e r a t i o n w a s p e r f o r m e d o r r e c o m m e n d e d .
T h e f a c t o r s c o n s i d e r e d w e r e d i a g n o s i s , a g e , s ex ,
a n d o b e s it y . A s f o r a g e , t h e p a t i e n t s w e r e s u b -
g r o u p e d i n t o t w o g r o u p s : a n e l d e r l y g r o u p ( > 6 0
y e a r s ) a n d a y o u n g e r g r o u p ( < 6 0 y e a r s ) . W e
d e f i n e d o b e s i t y a s a b o d y m a s s i n d e x ( B M I ) g r e a t e r
t h a n 2 7 u n i t s . B o d y m a s s i n d e x w a s c a l c u l a t ed
f r o m t h e p a t i e n t s ' b o d y w e i g h t i n k i lo g r a m s ( W )
a n d h e i g h t i n m e t e r s ( H ), w h e r e B M I = W / H 2, w i t h
a n o r m a l r a n g e b e t w e e n 2 I a n d 2 6 u n i t s . ~ T h e
m e d i a n B M I in t h e O A g r o u p w a s 2 8 u n it s ( q u a r -
t il e s, 2 5 a n d 3 0 ) , a n d i n t h e R A g r o u p i t w a s 2 4
u n i t s ( q u a r t i le s , 2 0 a n d 2 6 ) .
T h e p a t i e n t s i n t h e O A a n d R A g r o u p s w e r e s ig -
n i f i c a n t l y d i ff e r e n t f r o m e a c h o t h e r i n f o u r a s p e c t s
( M a n n - W h i t n e y U t e st ) :
A g e a t t i m e o f s u rg e r y ( m e d i a n a g e o f O A / R A
g r o u p s , 7 0 / 6 I y e a r s , P < .0 0 0 1 )
B o d y m a s s i n d e x ( m e d i a n B M I o f O A / R A
g r o u p s , 2 8 / 2 4 U , P < . 0 0 0 1 )
P r e o p e r a t i v e H o s p i t a l fo r S p e c i a l S u r g e r y s c o r e
( m e d i a n s c o r e o f O A / R A g r o u p s , 5 6 / 4 8 p o i n t s ,
P < . 0 0 0 1 ) .
P r e o p e r a t i v e d e v i a t i o n s f r o m t h e a c c e p t ab l e k n e e
a x i s b e t w e e n 3 ° a n d 1 0 ° of v a l g u s ( m e d i a n o f
d e v i a t i o n o f O A / R A g r o u p s , ] 0 o / 4 ° P <
. 0001 .
T h e r e f o r e , i t w a s n e c e s s a r y t o e x a m i n e t h e s u r v i v a l
r a t e s a n d t h e f a c t o r s t h a t m a y i n f l u e n c e t h e s e r a t e s
w i t h i n e a c h g r o u p s e p a r a t e l y .
T h e m e t h o d d e s c r i b e d b y A r m i t a g e 12 w a s
e m p l o y e d t o c o n s t r u c t s u r v i v o r s h i p t a b l e s. P a t i e n t s
w h o h a d d i e d o r w e r e l o st t o fo l l o w - u p e v a l u a t i o n
w e r e c e n s o r e d a c c o r d i n g t o t h e l a te s t a v a i l a b l e
a s s e s sm e n t . T h e l o g - r a n k t e s t w a s u s e d t o c o m p a r e
t h e c u m u l a t i v e s u r v i v a l r a te s o f t h e d i f f e r e n t
g r o u p s a n d s u b g r o u p s . O t h e r s t a t i s t i c a l t e s ts a r e
o t h e r w i s e s p e c if i e d . A P v a l u e l e s s t h a n . 05 w a s
c o n s i d e r e d s i g n i fi c a n t .
esu l t s
A t 1 2 y e a r s , t h e o v e r a l l c u m u l a t i v e s u r v i v a l r a te
w a s 9 2 . 3 ( 9 5 c o n f i d e n c e l i m i ts , 8 9 . 6 - 9 5 . 0 ) ,
w i t h a n a v e r a g e a n n u a l f a i l u r e r a t e o f 0 . 7 . T h e
s u r v i v a l c u r v e w i t h 9 5 c o n f i d e n c e l i m i t s f o r t h e
t o t a l m a t e r i a l i s s h o w n i n F i g u r e 1 . I n t h e O A
g r o u p t h e r e w e r e t h r e e f a i l u re s ( 2 c a se s o f l a t e
d e e p i n f e c t i o n a n d 1 c a s e o f m e c h a n i c a l l o o s e n -
T a b l e
1 . A S h o r t S t a t i s t i c a l R e p o r t o n t h e P r e - a n d
P o s t o p e r a t i v e K n e e A x i s a n d P o s i t i o n i n g o f
t h e
P r o s t h e t i c T i b i a l C o m p o n e n t i n t h e
T w o D i a g n o s t i c G r o u p s
P r e o p e r a t i v e P o s t o p e r a t i v e
O A R A A R A
Knee axis
M e d i a n
Lower quar t i le
Upper quar t i le
T ibia l t il t , an te rop os te r io r v iew
M e d i a n
Lower quar t i le
Upper quar t i le
Tibial t i l t , s ide v iew
M e d i a n
Lower quar t i le
Upper quar t i le
_3 ° 6 ° 5° 5°
_6 ° 2 ° 3° 4 °
6 ° l0 o 7 ° 7 °
_2 ° _2 °
0 o 0 o
_4 ° _3 °
° °
_1 o 0 o
3° 3°
OA, os teoar th rosis ; RA, rheumato id a r th r i t is ; - , v a rus /pos te -
rior t i l t .
1 o o
9 9
9 9
9 7
~ 9 s
~
99
~ 94
J
~ 93
~ s o
89
i
i '2 ; 'o '6 '9 ,'0 1', ;2 '
Y E A R S A F T E R O P E R A T I O N
F i g . 1 . C u m u l a t i v e s u r v i v a l r a t e o f t h e t o t a l m a t e r i a l .
H a t c h e d a r e a r e p r e s e n t s 9 5 c o n f i d e n c e l i m i ts .
8/19/2019 Survivorship Analysis of Cemented Total Condylar Knee Arthroplasty. a Long-term Follow-up Report on 348 Cases
http://slidepdf.com/reader/full/survivorship-analysis-of-cemented-total-condylar-knee-arthroplasty-a-long-term 3/4
i n g ) . T h e c u m u l a t i v e s u c c e s s r a t e o f t h e O A g r o u p
w a s 9 7 ( 9 5 c o n f i d e n c e l i m i ts , 9 4 . 7 - 9 9 . 5 ) , w i t h
a n a v e r a g e a n n u a l f a i l u r e r a t e o f 0 . 3 .
I n t h e R A g r o u p , t h e r e w e r e 1 3 f a i l u r e s ( 5 c a s e s
o f l a t e d e e p i n f e c t i o n , 6 c a s es o f m e c h a n i c a l l o o s -
e n i n g , a n d 2 c as e s o f t r a u m a t i c l o o s e n i n g ) . T h e
c u m u l a t i v e s u c c e s s r a t e i n t h e R A g r o u p w a s 8 7
( 9 5 c o n f i d e n c e l i m i ts , 8 2 . 2 - 9 1 . 8 ) , w i t h a n a v e r -
a g e a n n u a l f a i l u r e ra t e of 1 .2 .
T h e c u m u l a t i v e s u r v i v a l r a t e o f t h e O A g r o u p
w a s s i g n i f i c a n t ly h i g h e r t h a n t h a t o f t h e R A g r o u p
( F ig . 2 , P = .0 0 5 ) . N o n e o f t h e o t h e r v a r i a b l e s ( a g e ,
s e x , B M I ) h a d a s t a t i s t ic a l l y s i g n i f i c a n t e f f e c t o n
s u r v i v a l r a t e . A s u m m a r y o f t h e c u m u l a t i v e s u r -
v i v a l r a t e s i n r e l a t i o n t o t h e o t h e r f a c t o rs c o n s i d -
e r e d i n b o t h d i a g n o s t i c g r o u p s i s g i v e n i n T a b l e 2 .
i s cuss ion
I n p r o s t h e t i c k n e e r e c o n s t r u c t i o n , w h e r e t h e
m a i n i n d i c a t i o n is d e g e n e r a t i v e c h r o n i c p a i n , t h e
l o g i ca l c h o i c e o f t h e e n d p o i n t m u s t b e w h e n a
p a t i e n t h a s p a i n ; t h a t i s , a p r o s t h e t i c l i fe s p a n
w o u l d b e a p a i n - t o - p a i n c y c l e .
S o m e a u t h o r s c h o o s e p r o s t h e t i c r e v i s i o n a s t h e
e n d p oi n tl ,2 , 5, 6 ; o t h e r s a d d s e v e r e p a i n ( w i t h o u t
r e v i s i o n ) t o t h e r e v i s i o n c r i t e r i a a s a n e n d p o i n t d e f -
i n i t i o n . 8 O t h e r a u t h o r s a n a l y z e t h e i r m a t e r i a l s
a c c o r d i n g t o a v a r i e t y o f e n d p o i n t s . 4 , 7,13 W e p r e f e r
t o a p p l y r e v i s i o n a s t h e e n d p o i n t , a s it i s a c l e a r - c u t
a n d a c o m p a r a b l e c r i te r i on , w h i c h i s i n d e p e n d e n t
o f s u b j e c ti v i t y , a n d i t i s b a s e d p r e d o m i n a n t l y o n a
p a t i e n t ' s i n t r a c t a b l e r e s i d u a l p a i n . R a d i o g r a p h s a t
t h e t i m e o f d e c i s i o n m a k i n g f o r r e v i s i o n w i l l s u p -
p o r t t h e s u r g e o n ' s d e c i s i o n , as r a d i o l u c e n t z o n e s
c o r r e l a t e w i t h r e s i d u a l p a i n i n t e n s i t y , as w e
s h o w e d e a r l i e r . 1 4 , 1 5
S urv i v o rs h i p A na l y s i s o f T K A • N a f e i e t a l 9
1 0 0
9 9
9 8
9 7
9 e
9 5
9 4
9 3
w 9 2 .
~ 91-
~ 90
~
8 9 .
~ 88
87.
i 8 6
~ 8 5 .
~ B
8 3
81
8O
• O A
D R A
. . . . . . . I
1 2 3 4 ~ ~ ~ ~ 1 o
. 12
Y E A R S A F T E R O P E R A T I O N
F i g . 2 . C u m u l a t i v e s u r v i v a l r a t e s o f th e o s t e o a r t h r o s i s
( O A ) a n d t h e r h e u m a t o i d a r t h r i ti s ( R A ) g r o u p s . H a t c h e d
a r e a s r e p r e s e n t 9 5 c o n f i d e n c e li m i t s . P = .0 0 5 .
T h e o v e r a l l c u m u l a t i v e r a t e s o f s u r v i v a l i n th i s
s e r i e s ( 9 8 a t 5 y e a r s , 9 2 a t 1 2 y e a r s ) c o i n c i d e
w i t h t h o s e r e p o r t e d b y o t h e r a u t h o rs . 4 , 6 T h e c o m -
p a r i s o n w i t h o t h e r m a t e r i a l i s o f t e n w e a k e n e d b y
t h e f a c t t h a t o n l y f e w a u t h o r s r e p o r t t h e i r s u r v i v a l
r a te s a c c o m p a n i e d b y c o n f i d e n c e l i m i t s .
T h e m o s t p r o m i n e n t f e a t u r e o f t h i s s t u d y ' s
r e s u l ts i s t h e s i g n i f i c a n t d i f f e r e n c e b e t w e e n t h e
s u r v i v a l r a t e s o f t h e t w o d i a g n o s t i c g r o u p s , w h i c h
c o n f li c t s w i t h e a r l i e r r e p o r t s . R a n d a n d I l s t r u p
f o u n d t h a t t h e d i a g n o s i s o f R A w a s a v a r i a b l e
f a v o r i n g a h i g h o v e r a l l s u c c e ss r a t e w h e n t h e
w h o l e g r o u p w a s c o n s i d e r e d ( d i f f e r e n t t y p e s of
T a b l e 2 . T w e l v e - y e a r C u m u l a t i v e S u r v i v a l R a t e s o f t h e T w o D i a g n o s t i c G r o u p s
a s a F u n c t i o n o f D i f f e r e n t V a r i a b l e s
O s t e o a r t h r o s i s
G r o u p R h e u m a t o i d A r t h r i t is G r o u p
Var iab le n CSR CL n CSR CL
Age (years)
> 60 157 97.3 94.6-10 0 84 91.6 85.8-9 7.4
_< 60 27 100 - - 80 90.5 8 3.1-97 .9
Sex
Men 36 100 - - 33 81 .0 68 .2 -93 .8
W om en 148 96.5 93.6-9 9.4 131 90.4 85.6-95 .2
B o d y m a s s i n d e x
> 27 94 98.9 96.8-10 0 30 96.7 90.4-1 00
_< 27 90 95.2 90.9 -99.5 134 85.6 80.0 -91 .2
n , numb er o f cases in the subgroup ; CSR, cumu la t ive su rv iva l ra te ( ) a t 12 yea rs ; CL , 95 conf idence
limits .
8/19/2019 Survivorship Analysis of Cemented Total Condylar Knee Arthroplasty. a Long-term Follow-up Report on 348 Cases
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1
The Journa l o f Ar th rop las ty Vo l 11 No 1 Janu ary 1996
prostheses). 5 Nevertheless, wh en they considered
the 5-year survival probability of a prosthetic
design similar to the one used in our series, they
found no significant difference. Several other stud-
ies concluded that the diagnosis did not affect sur-
vival rates. 2,6A6 In ou r earlier repo rts on the same
prosthesis using the traditional case follow-up
method of assessment, we found no significant dif-
ference in outcome between the OA and RA
groups, only tendencies toward a better outcome
in the OA group.15,17-21 Nevertheless, when the
survivorship method of analysis was applied, the
OA group proved to have a significantly better out-
come than the RA group. This controversy con-
cerning the significance of the diagnosis on the
prosthetic survival rate and our finding of signifi-
cant differences between the two diagnostic groups
age, BMI, preoperative Hospital for Special
Surgery score, and preoperative alignment)
strongly suggest that investigators must stratify
their material according to the diagnosis.
In the present series no significant difference was
found between the survival rates of younger and
elderly patients within the diagnostic groups. The
findings re porte d by Ritter et a1.13 and Ran d a nd
Ilstrup 5 conc erni ng th e effect of age o n prost hesis
survival must be cautiously interpreted, as their
material was analyzed irrespective of the diagnosis.
For the purpose of comparability, we emphasize
the importance of stratified analysis and presenta-
tion of confidence limits and data about implant
positioning. Revision opera tion is the mos t suitable
endpoin t to apply.
cknowledgment
The authors thank Soren M. Bentzen, DMSc,
PhD, Institute of Cancer Research, Aarhus Univer-
sity, for his participation in the statistical analysis of
this work.
References
1. Knutson K, TjOrnstrand B, Lidgren L: Survival of
knee arthroplasties for rheumato id arthritis. Acta
Orthop Scand 56:422, 1985
2. Knutson K, Lindstrand A, Lidgren L: Survival of
knee arthroplasties: a nation-wide multicentre
investigation of 8000 cases. J Bone Joint Surg 68B:
795, 1986
3. Lettin AWE Kavanagh TG, Craig D, Scales JT: Assess-
ment of the survival and the clinical results of Stan-
more total knee replacements. J Bone Joint Surg
66B:355, 1984
4. Nilessen RGHH, Brand R, Rozing PM: Survivorship
analysis in total condylar knee arthroplasty. J Bone
Joint Surg 74A:383, 1992
5. Rand JA, Ilstrup DM: Survivorship analysis of total
knee arthroplasty: cumulative rates of 9200 total
knee arthroplasties. J Bone Joint Surg 73A:397, 1991
6. Scuderi GR, Insal l JN, Windsor RE, Moran MC: Sur-
vivorship of cemented knee replacements. J Bone
Joint Surg 71B:798, 1989
7. Tew M, Waugh W: Estimating the survival time of
knee replacements. J Bone Joint Surg 64B:579, 1982
8. Tew M, Waugh W, Forster IW: Comparing the results
of different types of knee replacements: a method
proposed and applied. J Bone Joint Surg 67B:775,
1985
9. Insall JN, Tria AJ, Scott WN: The total condylar pros-
thesis: the first 5 years. Clin Orthop 145:68, I979
I0. Insall JN, Ranawat CS, Aglietti P, Shine J: A compar-
ison of four models of total knee-replacement pros-
theses. J Bone Joint Surg 58A:754, 1976
11. Quaade E Andersen T, Astrup A: Adipositas. p.
2100. In Thaysen JH, Lorenzen I, Christensen LK
eds): Medicinsk Kompendium. Vol. 2. 13th ed. Nyt
Nordisk Forlag, Arnold Busck, Copenhagen, 1986
12. Armitage P: Statistical methods in medical research.
Blackwell Scientific, Oxford/Edinburgh, 197I
13. Ritter MA, Campbell ED: Long-term comparison of
the Charnley, Muller and Trapezoidal-28 total hip
prostheses: a survival analysis. J Arthroplasty 2:299,
1987
14. Nafei A, Nielsen S, Kristensen O, Hvid I: The press-fit
Kinemax knee arthroplasty: high failure rate of non-
cemented implants. J Bone Joint Surg 74B:243, 1992
15. Nafei A, Kristensen O, Kjaersgaard-Andersen Pet ah
Total condylar arthroplasty for gonarthrosis. Acta
Orthop Scand 64:421, 1993
16. Lewallen DG, Bryan RS, Peterson LFA: Polycentr ic
total knee arthroplasty: a ten-year follow-up study. J
Bone Joint Surg 66A:1211, 1984
17. Hvid I, Kjaersgaard-Andersen E Wethelund JO,
Sneppen O: Knee arthroplasty in rheumatoid arthri-
tis: four- to six-year follow-up study. J Arthroplasty
2:233, 1987
18. Kjaersgaard-Andersen P, Hvid I, Wethelund JO,
Sneppen O: Total condylar knee arthroplasty in
osteoarthritis: a four- to six-year follow-up evalua-
tion of 103 cases. Clin Orthop 238:167, 1989
19. Kristensen O, Nafei A, Kjaersgaard-Andersen Pet ah
The total condylar knee arthroplasty: long-term
results in treatmen t of rheumatoid arthritis. J Bone
Joint Surg 74B:803, 1992
20. Nafei A, Steinke MS, Horlyck E: Total condylar knee
arthroplasty in the treatment of osteoarthritis and
rheumatoid arthritis: a comparative study at 4-8
years follow-up. Am J Knee Surg 3:59, 1990
21. Nafei A, Kristensen O, Hvid Ie t al: Long-term results
of cemented total condylar knee arthroplasty: 9 to
11 years follow-up. Acta Orthop Scand 63 suppl
248), 1992