p h y s io th e ra p y , M a rch 1983, v o l 39, n o 1 13 THE ROLE OF THE QUADRICEPS MUSCLE IN KNEE EXTENSION! E L L I S S. J A N K S , B.Sc. ( P h y s io th e r ap y ) ( W itw a te rs ra nd )* SUMMARY In 1949, S m illie p ro p o sed that the vastus m edialis m uscle alone is responsible f o r the f in a l 10° to 15° o f k n ee extension. A num ber o f m ore recent studies have p ro v e d th a t the whole quadriceps muscle is responsible f o r a ll degrees o f knee extension. This evidence is review ed a n d th e fu n c tio n o f the two subdivisions o f the vastus m edialis is discussed. WHAT IS TH E R O L E O F T H E V A STUS M E D IA L IS M USCLE IN KNEE EXTENSION? Ma n y p hy si ot he ra pi st s have p r o b a b l y been t a u g h t t h a t the vastus medialis alo ne is re sponsible f or the final 10° to 15° of knee extension ( G a r d i n e r , 1976; L an tz o un is , 1931; Smillie, 1949; Smillie, 1970; W ay n e Kressley, 1963; Yo cu m e t a/., 1978). Ho w ev e r, this o p in io n h a s be en ch all enged by o t h e r au thors (B a sm aj ia n, 1974; Br e we rt o n, 1955; Hal len a nd Lindahl, 1962; Lieb a n d Perry, 1968; Lieb a n d Perry, 1971; Santavirta, 1971; Wild e ta l., 1982). The aim o f this article is to review the evidence u p o n which these t w o o p p o si n g opinions are based. The view t h a t the va stus medialis acts selectively d u r i n g the last 10° to 15° o f kn ee e x te n s io n is ba sed o n t w o l i n e s o f evidence. First, the British o r t h o p a e d i c sur ge on , Smillie (1949 and 1970) p r o p o se d t h a t there are two muscle g r o u p s th at are active du ri ng di fferent ph as es o f kn ee extension. T he first comprises the vastus rnter med iu s, vastus lateralis a n d rectus femoris muscles whi ch , u n d e r n o r m a l c ir cu ms tan ces , e xtend the knee to within 10° to 15° o f full knee ex tension. The second c o m p o n e n t is the selective ac ti on o f va stus medialis which extends the kne e t h r o u g h the last 15°. Smillie ca m e to this conclusion pu re ly on the basis o f p a lp a t io n a n d visual observation o f the q u a d r ic e p s muscle g r o u p c o n tr a ct in g through the full range o f knee extension. Second is the c o m m o n o b s e r v a t i o n th at, following a period o f lower limb i m m o bi liz at io n , no t o nl y is knee extension impa ired , b u t there a p p e a r s to be selective a t r o p h y of the vastus medi alis, which p re ced es a t r o p h y o f the o t h e r knee ex tensor m uscles (Lie b a n d Perry, 1971). It is an un derstandable de d u c t i o n t h a t these two o b s e rv at io ns are causally related a n d t h a t the a t r o p h y o f va st us medi ali s is the principal re as o n f or im p ai red knee exte nsi on a fte r lower limb imm obilization. Against this i n te r p r e t a ti o n st a n d s the fol low ing evidence: First, when c o n tr a c t i o n o f the va stus medialis is inhibited (as seen visually a n d p r o v e n by e le c t ro m y o g r a p h y ) by infiltration with local an aes th eti c, the full force a n d range o f active knee ex tension is u n i m p a i re d (Lieb a n d Per ry , 1971), indicating th at the o t h e r q u a d r ic e p s muscles can fulfil b ot h these functions. t Part o f a pr oj ect a im e d a t f o r m u la t in g a c om p re hen siv e Pos t-meniscectomy r eh abi lit ati on p r o g r a m m e . Presently stu dyi ng f or the B.Sc. ( M e d) ( H o n s ) Spo rts Science at the University o f C a p e To wn . R eceived 16 S e p te m b e r 1982. O P S O M M IN G In 1949 h e t Sm illie voorgestel dat m. vastus m edialis alleen verantw oordelik is vir die fin a le /0° tot 15° van k n ie ekstensie. 'n A a n ta l latere stu d ies het bew ys d a t die hele m. quadriceps v erantw oordelik is vir die geheel van knie e kstensie. H ierdie bew yse w ord bespreek en die f u n k s ie van die tw ee subdivisies van m. vastus m edialis w ord bespreek. S econd, S a n ta vi rt a (1979) f o u n d t h a t three m o n t h s after r o ut in e meni sce ct om y, the extension force o f the qu a d ric ep s muscles o f the o p e r a t e d leg was e q u a l to t h a t o f the n o n - o p e r a t e d c o n t r o l l e g s . H o w e v e r , i n t e g r a t e d e le c t r o m y o g r a p h y revealed that v a st u s medialis activity was m u ch re du ced in the qu a d r ic ep s muscles o f the o p e r a t e d legs. T hi s indicates t h a t a t r o p h y o f va stu s medi ali s c an oc cur without i m p a i r m e n t o f kne e extension; a n d co n fir m s the finding o f S a n ta vi rt a (1979) t h a t the o t h e r q ua d r ic ep s muscles can c om p e n sa te for the re duced va stus medialis f un cti on a n d p r o d u c e n o r m a l exte nsi on po w e r . Third, e le c t r o m y o g r a p h i c studies have clearly sh ow n th at rectus femoris, va stus in te rm ed iu s, vastus lateralis an d vastus medialis longus (see later) are all active d u r in g the full range o f knee ex tension ( Ba sm aji an, 1974; Hallen a n d L in d a hl , 1962; Lieb a n d Perry, 1971; S a nt av i r t a, 1979 a n d Wild et al., 1982). F u r t h e r m o r e , e le c t r o m y o g r a p h i c activity of all these mu scles is m ax i m al w he n the knee is a lm o st fully exte nde d (Wild e ta l., 1982). This c an in fact be d e d uce d from c o n s i d e r a ti o n o f the m ec h an ic s o f k n e e ex tension. Because the knee experiences a great re d u ct io n in m echan ical a d v a n t a g e d u r i n g the last 15° o f kn e e exte nsi on , it follows th a t the e x te n so r muscles m u s t exert a g reater (60%) force in o r d e r to m ov e the kn ee t h r o u g h this range. Th er e fo re , failure to achieve full ex tension o f the knee m u st be a reflection of we ak ne ss o f the entire q u a d r ic ep s muscle a n d n o t j u s t the va stu s media lis (Lieb a n d Perry, 1968 a n d Wild e t al., 1982). Fourth, Lieb a n d Per ry (1968 a n d 1971) f o u n d t h a t the va stus medialis c o ul d be divided into two p a r t s on the basis o f the di rectional a li gn m en t o f its fibres. Th e p r ox im a l fibres (va stus m edialis longus), o ri e n t a t e d at angles o f 15° - 18° to the l ong axis o f the fe m u r, extend th e knee. T h e distal fibres (va stus medialis o b liq ue ) which are co vered wi th a very thin fascia, a n d p r o d u c e the p r o m i n e n t bulge su p e r o - m ed ia l to the p ate lla , insert m o r e o bl iqu el y at between 50° a n d 55°. T h e y t ak e no p a r t in ex ten di ng the kne e, b u t align the patella d u r i n g kne e extension. It is therefore clear th at the visible wasting o f the vastus medialis muscle is actu all y wa sti n g o f the visually p r o m in e n t vastus medialis o bl iqu e p o rt io n , which does no t pa rti cip ate in knee extension, n o r does it externally ro tat e the tibia on the f e m ur d u r i n g the final 10° to 15° o f knee extension. This r o t a t i o n o f the tibia, which helps to stabilise the knee when it is in full ex tension, is a result o f lig a m en t o u s forces a n d a rt i cu l a r a li g n m e n t r a th e r th an m u s c u la r a ct io n (Lieb a n d Perry, 1971). T he im p o r t a n c e o f this tibial m o v e m e n t was n ot ed by Smillie (1949 a n d 1970) w h o p r o p o s e d incorrectly t h a t it was d u e to the ac ti on o f v a st u s medi alis which he there fo re called “ the key (muscle) to the k n e e ” . It is p r o b a b ly R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) 14 F isio te ra p ie , M aa rt 1983, d e e l 39, n r 1 be cause o f this in co rr ect i n te r p r e t a ti o n t h a t so m uch im p o r t a n c e ha s been a tt a c h e d to va stu s medialis. Finally, there m a y be o t h e r causes o f defective ex tension of the knee which have n o t h in g to do with we akness o f the va stu s medialis muscle. Reflex inhib it ion o f the q ua dr ic ep s muscles c aus ed by p ain (H al len a n d Lin d ah l, 1962; W ild et a/., 1982) a n d a d h e s io n f o r m a t i o n a r o u n d the knee jo in t d u r i n g pe rio ds o f im m o b i li z at i o n (H al len a n d L ind ah l, 1962) c ou ld c o n tri b ut e. C O N C L U S I O N Recen t scientific studies pr o v e th a t the vastus medialis muscle is n o t solely re sponsible f o r the final degrees o f knee ex tension, b u t th a t all the q u a d r ic ep s muscles play a p a r t in this action. L ow e r limb im m o b i li z at i o n results in w e ak e n in g o f all the qu a d r ic ep s muscles. D u r i n g re ha b ili ta ti o n after such a p er iod , it is there fo re i m p o r t a n t to a tt a in a d e q u a t e st rength o f all the q u a d r ic e p s muscles a n d no t j u st v a st us medialis. It w o u ld seem, how ev er, t h a t special a tt e n ti o n sh o u l d be paid to the vastus medialis o b liq u e to ensure o p t i m u m pa te lla r ali g nm en t d u r i n g knee m ov em e n t. References Ba smajian J. V. (1974). Muscles alive; T h e i r functions revealed by e le ctr om yog rap hy . 3rd Ed. Williams and Wilkins. Baltimore. 258-267. B re we rt on D. A. (1955). Th e f un cti on of the va stu s medialis muscle. Ann. Phys. M ed. 2, 164-168. G a r d i n e r M. D. (1976). T he principles o f exercise therapy. 3rd Ed. G. Bell a n d Sons. L o n d o n , p. 163. Ha lle n L. G. a n d Lin d ah l O. (1962). Muscle f u nc tio n in knee extension: An E . M . G . study. A cta. Orthop. Scand. 32, 457- 460. L a n t z o u n i s L. A. (1931). D e r a n g e m e n t o f the menisci o f the knee jo in t . Surg. Gynec. O bstet. 53, 182-188. Lieb F. J. a n d Pe rr y J. (1968). Q u a d r i c e p s function: An a n a t o m i c a l a n d mec han ic al st u dy using a m p u t a t e d limbs. J. B one. Joint. Surg. 50 A, 1535-1548. Lieb F. J. a n d Per ry J. (1971). Q u a d r i c e p s fu nction: An E .M .G . st u dy u n d e r isometric con d iti o n s. J. Bone. Joint. Surg. 53 A, 749-757. Sa n t a v i r t a S. (1979). In t eg r a te d e le c t r o m y o g r a p h y o f the va stu s medialis muscle a fte r men iscectomy. A m . J. Sports. M ed. 7, 40-41. Smillie I. S. (1949). T h e q u a d r ic ep s in rela tion to recovery fr om injuries to the knee jo in t. P h ysiother 35, 51-57. Smillie I.S. (1970). Injuries to the knee jo int . 4th Ed. Liv ingstone. E d in b u r g h a n d L o n d o n . 2-3. Wa yn e Kressley N. (1963). Progressive exercise pr o g r am f o l l o w i n g m e n i s c e c t o m y : U t i l i z a t i o n o f l e n g t h e n in g c o n tr a c t i o n s. P h ysio th e r 43, 263-264. Wild J. J. , Fra nk lin T. D. and W o o d s G. W. (1982). Patellar p a in a n d q u a d r ic e p s r eh abi lit ati on : An E . M . G . study. Am. J. Sports. M ed. 10, 12-15. Yoc um L. A., B a ch m an D. C., Bates-Noble H. a n d Hoover R. L. (1978), T h e de ra n g e d knee: R e st o ra ti o n o f function A m . J S p o rts. M ed. 6, 51-53. R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) p h y s io th e ra p y , M a rch 1983, vo ! 39, n o 1 15 LUMBAR SUPPORT CUSHION — f o r u s e in th e c a r, in th e h o m e , e tc. — c o lo u r s : b e ig e , b ro w n , b u r g u n d y , n a vy, b la c k . R e ta il p ric e : R 1 0 .5 0 in c l N E C K - E E Z E CERVICAL SUPPORT CUSHION — f it s in to s ta n d a rd p illo w ca se — h ig h q u a lit y fo a m R e ta il p ric e : R 1 2 .0 0 in c l W h o le s a le p ric e s a v a ila b le to m e d ic a l p ra titio n e r s , p h y s io th e r a p is ts , p h a rm a c ie s e tc ENTAP (PTY) LTD P.O . B o x 5 2 45 2, S a x o n w o ld , 2132. T e l: (01 1 ) 7 8 8 -3 3 0 7 WORLD CONFEDERATION FOR PHYSICAL THERAPY E X E C U TIV E C O M M ITTEE The Executive C o m m it te e elected at the T en t h General Meeting held in S t oc kh ol m , May 1982, is as follows: President M iss M List 1st Vice-President Miss I Od een 2nd Vice-President M r D T eag er 3rd Vice-President M r T T ir a n a s a k General Members Australian Ph y s io t h e r a p y Association: Miss P T r o tt Ca n ad ian P h ys io th e r ap y Association: M r A J F e r n a n d o Japa nes e Physical T h e r a p y Association: M r T M or in a ga Nigeria Society o f Ph ys iot he rap y: M r H A N Oke ke Section for Physical Th era py , Polish Society for Preventing & C o m b a t i n g Disability: Mrs M Su w al sk a American Physical T h e r a p y As sociation: Miss R W o od The first interim mee ting o f the C o m m i t te e will be held in London, Ju ly 1983. RATIO OF P H Y S IO T H E R A P IS T S TO P O P U L A T IO N . Two thirds o f the M e m b e r O r ga ni sa ti on s s u b m itt e d d a t a on membership o f ass oc iatio n; n u m b e r registered, licenced or recognised; n u m b e r practising; n u m b e r in f u l l/ p a r t- t im e practice; n u m b e r g r a d u a t e d d u r i n g 1980 a n d the ratio of P ysiotherapists p er p op u l a t i o n . F o r S o u t h Africa figures were: 1185 mem be rs, 1550 registered, 965 in practice, 110 graduated in 1980 a n d the ra tio is 1 p hy si ot he ra p is t to 15,350 population. T he l att er varied f r o m I to ± 960 (Belgium) to I 0 620909 (India), with most M e m b e r O r g a n i sa t i o n s having ratio of I to 3 000 to 6000. N EW S F R O M M E M B E R O R G A N IS A T IO N S Denmark A full-time 10-month p o s t g r a d u a t e course for teache rs and clinical ph y sio th era p is ts a n d oc cu p a ti o n a l th er a p is ts was set up by the Ministry o f the I nt er io r in A r h u s in S e p te m b e r 1980. T he course is integ rate d for tea chi ng p hy si o th er a py an d oc cu p a ti o n a l th er a p y a n d subjects cover: pedago gy (psychology, a d m i n i s t r a t i o n , e n v ir o n m e n t an d health); p h y s io th er a py a nd o c cu p a ti o n a l th er a py ( c o m m o n an d se p a ra te subjects); several o p tio na l subjects in classes, gr o u p sessions o r individual papers. Spain T he Sp a ni sh Asso cia tion will host the 14th Congr es s o f the E u r o p e a n C o n f e d er a ti o n for Physical T h e r a p y 1 7 - 2 1 J u n e 1984 in Ba rcelona (see notice elsewhere). Surinam In t r o d u c t i o n to n e u r o d e v e lo p m e n ta l tr ea tm e n t, a trai nin g cour se in Bo b a th principles was t a u g h t by Pa ul Helders and Gert B o u m a n o f H o ll an d , su p p o r t e d by a local or th o p a e d ic surg eo n, ne urologist, p aed iat ri cia n , psycho log y an d speech therapist. R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. )