Amputee stump radiology

h a s t o b e a d a p t e d t o t h e q u a l i t i e s o f t h e s t u m p w h i c h a r e d i f f e r e n t f rom t h e c o r r e s p o n d i n g p a r t o f a n o r m a l l i m b . S p e c i a l t e c h n i q u e s p e r m i t f u r t h e r d i a g n o s i s . I n t r o d u c t i o n I n m a n y r e s p e c t s , r a d i o l o g y o f t h e a m p u t a t i o n s t u m p is d i f f e r e n t in t e c h n i q u e , i n d i c a t i o n a n d i n t e r p r e t a t i o n c o m p a r e d w i t h X r a y e x a m i n a t i o n o f a c o r r e s p o n d i n g p a r t of t h e i n t a c t e x t r e m i t y . T h u s , in s t a n d a r d a n d o t h e r X r a y s m a d e w i t h t h e s a m e c r i t e r i a usua l ly a p p l i e d t o a n o r m a l l i m b , r e s u l t s a r e o f t en v e r y d i s a p p o i n t i n g . T h e p u r p o s e of th i s p a p e r is t o p r e s e n t t h e p a r t i c u l a r a s p e c t s o f t h e a m p u t a t i o n s t u m p f r o m t h e p o i n t o f v i e w of X r a y e x a m i n a t i o n t o o b t a i n a m a x i m u m of d i a g n o s t i c i n f o r m a t i o n w i t h a m i n i m u m of e x p o s u r e t o r a d i a t i o n . T i s s u e qual i t i es T h e t i s s u e s o f t h e s t u m p dif fer f r o m t h e n o r m a l l i m b in t w o r e s p e c t s . F i rs t ly t h e g e n e r a l d i a m e t e r is u s u a l l y less t h a n n o r m a l . If n o t , t h e r e m i g h t b e s w e l l i n g c a u s e d by o e d e m a o r h a e m a t o m a , b o t h p r e s e n t i n g r a t h e r a s l ight o b s t a c l e t o X r a y s c o m p a r e d t o m u s c l e s a n d b o n e s . S e c o n d l y , t h e d e n s i t y o f t h e b o n y t i s sues is a l w a y s l e s s c o m p a r e d w i t h t h e n o r m a l l i m b . T h e r e is n o r m a l l y p r e s e n c e o f o s t e o p o r o s i s in s o m e d e g r e e , u s u a l l y d u e t o o l d a g e , inac t iv i ty o r b o t h . T h e o n l y e x c e p t i o n is t h e b o n e i m m e d i a t e l y a f t e r a m p u t a t i o n o n a y o u n g , o t h e r w i s e h e a l t h y p a t i e n t . F i n a l l y , t h e r a d i o l o g i c a l d e n s i t y o f t h e s t u m p c o n s i d e r a b l y d e c r e a s e s f r o m p r o x i m a l t o d i s t a l d i r e c t i o n . F o r d i a g n o s t i c e v a l u a t i o n , t h e i n t e r p r e t a t i o n o f t h e sof t t i s s u e s in a s t u m p is j u s t a s i m p o r t a n t a s b o n e a n d j o i n t s . In a d d i t i o n t o t h a t , w e a r e i n t e r e s t e d in t h e p r o x i m a l a n d t h e d i s t a l p a r t o f t h e s t u m p a s we l l ( F i g . 1). A p e c u l i a r i t y o f s t u m p r a d i o l o g y is e x a m i n a t i o n w i t h t h e p a t i e n t w e a r i n g h i s p r o s t h e s i s . O n t h e s e p i c t u r e s , t h e i n n e r wa l l o f t h e s o c k e t s s h o u l d b e c o m e v is ib le , t h e d e n s i t i e s 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 ( w o o d , l a m i n a t e d p l a s t i c s , m e t a l ) a r e d i f f e r e n t ; if p o s s i b l e , m e t a l p a r t s of t h e p r o s t h e s i s s h o u l d n o t o v e r l a p s t u m p t i s s u e s i m p o r t a n t fo r d i a g n o s i s . T e c h n o l o g y S i n c e soft t i s s u e s , b o n e s a n d e v e n p r o s t h e t i c c o m p o n e n t s s h o u l d b e v is ib le o n t h e X r a y f i lm, l o w c o n t r a s t t e c h n i q u e s , e v e n in s t a n d a r d e x p o s u r e s , a r e n e c e s s a r y u s i n g a s y s t e m of films a n d s c r e e n s w i t h l o w g r a d a t i o n , h i g h k i l o v o l t a g e a n d a w e d g e s h a p e d a l u m i n i u m fi l ter . I f o n e is i n t e r e s t e d o n l y in d e t a i l s , d i r e c t m a g n i f i c a t i o n t e c h n i q u e w i t h a focus less t h a n 0 . 3 m m c o n t r o l l e d b y t e l e v i s i o n g ives a n o p t i m u m of s h a r p n e s s a n d c o n t r a s t . If e m p h a s i s is p u t o n t h e sof t t i s s u e s , w e r e c o m m e n d t h e e x p o s u r e w i t h l o w k i l o v o l t s a s u s e d in m a m m o g r a p h y . Fig. 1. Two X-rays of the same above-knee stump. Left, standard exposure for the femur, over-exposed tip of the femur. Soft tissues only partially visible. Right, low contrast technique shows the whole of the femur and also the soft tissues. The quality of the soft tissues covering the bone and a skin ulceration on the medial side become visible. F o r f u r t h e r d i a g n o s i s , s p e c i a l t e c h n i q u e s s u c h a s x e r o r a d i o g r a p h y ( O t t o & W e l l a u e r , 1977) , t o m o g r a p h y , a r t e r i o g r a p h y a n d fistulography m i g h t b e i n d i c a t e d . In a r t e r i o g r a p h y , w e r e c o m m e n d t h e S e l d i n g e r t e c h n i q u e w h i c h i n s e r t s t h e c a t h e t e r i n t o t h e f e m o r a l a r t e r y of t h e o p p o s i t e s ide t o p r e v e n t a n y d a m a g e t o t h e s t u m p a r t e r i e s w h i c h a r e u s u a l l y a l r e a d y i m p a i r e d . I n fistulography, w e in jec t a w a t e r s o l u b l e c o n t r a s t l i qu id u n d e r p r e s s u r e us ing a c o n e s h a p e d b u l b i n s t e a d of a n e e d l e (F ig . 2 ) . T h i s t e c h n i q u e is s i m p l e a n d d o e s n o t r e q u i r e o t h e r t h a n s t a n d a r d X r a y e q u i p m e n t . D i a g n o s t i c s A t t h e t i m e of a m p u t a t i o n , m o s t p a t i e n t s a l r e a d y p r e s e n t a m a r k e d o s t e o p o r o s i s of t h e c o r t i c a l a n d c a n c e l l o u s b o n e . A f t e r a m p u t a t i o n , al l p a t i e n t s p r e s e n t s o m e d e g r e e o f o s t e o p o r o s i s e v e n if t h e y a r e r e g u l a r l y w e a r i n g a p r o s t h e s i s . If t h e s t u m p p r e s e n t s a n d b e a r i n g q u a l i t i e s a n d t h e p a t i e n t is a d e q u a t e l y f i t ted w i th a p r o s t h e s i s , t h e d e g r e e of o s t e o p o r o s i s is less i m p o r t a n t . S ince o s t e o p o r o s i s in s t u m p s is o f t e n ve ry m a r k e d a n d i r r e g u l a r , it m i g h t b e c o n f u s e d w i th S u d e c k d y s t r o p h y . T h i s d i a g n o s i s c a n n e v e r b e b a s e d o n X r a y e x a m i n a t i o n o n l y . E v e r y a m p u t a t i o n s t u m p a l s o s h o w s a c e r t a i n m u s c l e a t r o p h y . I n u n i l a t e r a l a m p u t a t i o n , th is a t r o p h y is e x a g g e r a t e d s ince t h e r e is r e g u l a r l y a c o m p e n s a t o r y h y p e r t r o p h y o f t h e o p p o s i t e s i d e . S t u m p a t r o p h y is m o r e i m p o r t a n t if t h e p a t i e n t is u n a b l e t o a c t i v a t e h i s s t u m p o r if t h e p r o s t h e t i c f i t t ing i m m o b i l i z e s m o r e m u s c l e s t h a n n e c e s s a r y . T h u s , s t u m p a t r o p h y o f t h e t h igh in b e l o w k n e e a m p u t e e s is m u c h m o r e i m p o r t a n t in p a t i e n t s w e a r i n g a p r o s t h e s i s w i t h t h igh cuff t h a n in t h o s e fitted w i t h a t o t a l c o n t a c t b e l o w k n e e p r o s t h e s i s . I n p a t i e n t s a m p u t a t e d b e f o r e t h e e n d of g r o w t h , d i f f e r e n c e s in s i ze of b o n e s a n d j o i n t s a r e p r e s e n t . D e p e n d i n g o n t h e e p i p h y s e a l g r o w t h l i n e s w h i c h h a d t o b e sacr i f iced a t a m p u t a t i o n , t h e s t u m p wil l a l s o p r e s e n t b o n y o v e r o r u n d e r g r o w t h . T h e y o u n g e r t h e a g e of t h e p a t i e n t a t t h e t i m e o f a m p u t a t i o n t h e m o r e i m p o r t a n t t h e s e g r o w t h e f fec t s will b e in s o m e c a s e s a n d m i g h t n e c e s s i t a t e s t u m p c o r r e c t i o n s ( B a u m g a r t n e r 1979) . A t r o p h y n o t o n l y o c c u r s in b o n e a n d m u s c l e s o f t h e s t u m p , b u t a l s o in t h e a r t e r i e s a n d v e i n s . A s fo r i n s t a n c e in leg p a r a l y s i s fo l l owing p o l i o m y e l i t i s , l e ss ce l l s a r e t o b e p r o v i d e d w i t h b l o o d a n d fo r t h e r e m a i n i n g t i s sues t h e r e is less a c t i v i t y a n d t h u s l ess e n e r g y c o n s u m p t i o n . C o n s e q u e n t l y n a t u r e a u t o m a t i c a l l y d i m i n i s h e s t h e d i a m e t e r o f t h e b l o o d ve s se l s (F ig . 3 ) . W i t h t h e p a t i e n t g e t t i n g o l d , a r t e r i o s c l e r o t i c c h a n g e s a n d e x t e r n a l p r e s s u r e s f r o m p r o s t h e s e s o f t e n c a u s e e a r l y a r t e r i a l o b l i t e r a t i o n . I n p a t i e n t s w i t h Fig. 2. Three examples of fistulography. Left, bursa on a short above-knee stump filled with contrast liquid. Middle, lateral fistula on a below-knee stump. The cone marks the orifice of the fistula which unexpectedly does not reach the tip of the fibula but the end of the tibia. Right, fistula on an above-elbow stump caused by electric burns. Fistula following the stump of the radial and ulnar nerve filling a cavity in the axilla. p e r i p h e r a l v a s c u l a r d i s e a s e , c a l c i u m d e p o s i t s e v e n in s m a l l e r a r t e r i e s a r e v is ib le o n s t a n d a r d X r a y s . R a d i o l o g i c a l e x a m i n a t i o n is p a r t i c u l a r l y i m p o r t a n t in d i a g n o s i s of t h e p r o b l e m s w h i c h f r e q u e n t l y o c c u r a t t h e s t u m p e n d . T h e b o n y s t u m p h a s t o b e ca re fu l ly r o u n d e d a t t h e o p e r a t i o n . If t h e s t u m p h a s t w o o r m o r e b o n e s s u c h a s in b e l o w k n e e o r m i d f o o t a m p u t a t i o n s t h e r e l a t i o n in l e n g t h b e t w e e n t h e s e b o n e s is ve ry i m p o r t a n t . O v e r l e n g t h of o n e b o n e m i g h t c a u s e t r o u b l e s . S e c o n d a r y c h a n g e s of b o n e c o n ­ figuration a t t h e e n d o f t h e s t u m p a r e v e r y f r e q u e n t a n d o f t e n c a u s e p r o b l e m s . G r o w t h o r c h r o n i c e x t e r n a l p r e s s u r e by t h e p r o s t h e s i s c a n r e s u l t in t h e b o n e b e c o m i n g s l im l ike a p e n c i l a n d t h u s p e r f o r a t e t h e soft t i s sues a n d g ive r ise t o c h r o n i c i n f e c t i o n . O f t e n t h e r e is a l a rge b u r s a filled w i t h c a l c i u m d e p o s i t b e t w e e n t h e soft t i s s u e s a n d t h e b o n e . M o r e o f t e n , t h e s t a n d a r d X r a y s h o w s e v i d e n c e o f b o n y o v e r g r o w t h f r o m a m i n i m a l s p u r t o a h u g e e x o s t o s i s . I f t h e r e is a c u t e o r c h r o n i c o s t e o m y e l i t i s , e r o s i o n s a n d s e q u e s t r a t i o n s m a y b e p r e s e n t . In a d d i t i o n t o s t a n d a r d r a d i o g r a m s , fistulography a n d t o m o g r a m s m i g h t b e i n d i c a t e d (F igs . 2 & 4 ) . O n s t a n d a r d X r a y s , t h e c o n t o u r s o f t h e s t u m p , t h e p o s i t i o n o f t h e m u s c l e s a n d of t h e m a j o r ve s se l s a n d n e r v e s as we l l s h o u l d b e v i s i b l e . W e a r e l o o k i n g for t h e d e g r e e of m u s c l e a t r o p h y a n d e v e n t u a l r e t r a c t i o n o f m u s c l e s . O n t h e r a d i o g r a m in t h e s ag i t t a l p l a n e , t h e s t u m p of t h e m a j o r n e r v e s m i g h t b e c o m e v i s ib le , p a r t i c u l a r l y if a n e u r o m a is p r e s e n t (F ig . 5 ) . F o r e i g n b o d i e s m u s t b e iden t i f i ed e v e n if t h e y a r e n o t a s o p a q u e as m e t a l . S u t u r e s in s t u m p s m o r e o f t e n c a u s e g r a n u l o m a a n d fistulae as in c u r r e n t o r t h o p a e d i c s u r g e r y . T r a u m a of t h e s t u m p m i g h t c a u s e f r a c t u r e s a n d m o r e f r e q u e n t l y a l a rge h a e m a t o m a a t i ts e n d . I n a m p u t a t i o n s fo r m a l i g n a n c i e s , w e m u s t l o o k for m e t a s t a s e s ( F i g . 6 ) . If t h e y a r e n o t v i s ib l e o n s t a n d a r d x r a y s , a r t e r i o g r a p h y a n d s c i n i t g r a p h y g i v e f u r t h e r i n f o r m a t i o n . R a d i o l o g i c a l e x a m i n a t i o n o f t h e s t u m p w i t h i n t h e p r o s t h e s i s s h o u l d n o t b e a r o u t i n e p r o c e d u r e . In diff icult s t u m p c o n d i t i o n s , h o w e v e r it c a n b e h e l p f u l in a c h i e v i n g a p r o s t h e t i c fitting w i th a t o t a l c o n t a c t s o c k e t . In leg a m p u t e e s , r a d i o g r a m s w i t h a n d w i t h o u t l o a d p r o v i d e e v i d e n c e o f t h e s o m e t i m e s s u r p r i s i n g d i f f e r e n c e s in t h e p o s i t i o n o f t h e s t u m p in t h e p r o s t h e s i s . C o n c l u s i o n s I n s t u m p p r o b l e m s , r a d i o l o g i c a l e x a m i n a t i o n is o f g r e a t h e l p in d i a g n o s i s . T o e v a l u a t e t h e Fig. 3. Arteriogram of a 60 years old patient who underwent an above-knee amputation 30 years ago. The contrast liquid is injected by a femoral catheter at the opposite side. Considerable narrowing of the diameter of the left iliac arteries. Obliteration of the femoral artery. Osteoporosis of left femur and left half of the pelvis. Fig. 4. Traumatic above-knee amputation with chronic osteomyelitis. The tomogram (right) provides better evidence of the size and site of sequestrations.