Intrinsic muscles of the hand: an overvieuw.

Intrinsic muscles of the hand: an overvieuw. Et Referat av IFSHT kongress en appetitt vekker til høstseminaret!!! Sydney 11-15 mars 2007 8 Mars tok jeg fly til Stockholm og samme med tre Svensker fløy jeg videre til Sydney. Det var en lang reise som gikk overraskende bra. Vi var der en dag i forkant av the council meeting og den dagen trengte vi så absolutt for en tidsforskjell på 11 timer er ikke bare bare!! Det var sen sommer i Sydney og det var varm, veldig varm. Og solen stekte ubønnhørlig, noe som to av de svenske, som hadde fri den 11 mars, smertelig fikk erfare. Å legge seg på stranden uten å bruke solcrème er ikke akkurat veldig smart i Australia. Ai ai de så ikke særlig bra ut L Bortsett fra en skikkelig jetlagg var jeg de første dager også litt forvirret av at solen beveger seg i feil retning. Du skulle ikke tro at det kan være så forvirrende men det ble det faktisk. Jeg har vart på sørlig halvfronten før men det har ikke forstyrret meg så mye som det gjorde i Australia. Antagelig fordi jeg var ute etter å sitte i skygge så mye som mulig men den skygge utviklet seg jo i feil retning slik at jeg bestandig endte opp i solen ;-) Søndag 11 mars var det den store council meeting hvor jeg representerte Norge som internasjonal kontakt. Det var en lang og intens møte, som det pleier å være. Referatet av dette finner du inn min årlige rapport som internasjonal kontakt. Selve kongressen begynte søndagskveld med en åpenings seremoni som var veldig spesiell med opptreden av noe aboriginer. Det deltok 513 terapeuter fra 32 land. Og så var det ca 1500 kirurger. Så det var ikke ett liten kongress. Istedenfor å gi ett overfladisk oversikt av det som skjedde gjennom kongressen velger jeg å gå inn i dybden. Og gi ett referat fra en workshop som jeg deltok på og som henger fint i hopp med noen av tingene Ton Schreuders kommer til å ta opp på vårt høstseminar. Så egentlig kan dette referatet bli sett som en appetitt vekker til høstseminaret. Jeg skal prøve så godt jeg kan å forklare hva Judy Colditz snakket om i sin workshop med tema Intrinsic muscles of the hand: an overvieuw. Det var egentlig ikke så mye workshop de var mer en forelesning I en mindre gruppe. Vi satt i salen og hørte på. Judy hadde dessverre ikke noe handout og jeg skrev og skrev så jeg fikk kramper. Jeg skal gjøre mitt beste å gjengi innholdet på workshoppen så godt som mulig men ikke tar alt jeg skriver for gitt. Jeg kan dessverre ikke garantere at det ikke er smyget inn seg noe feil. Men hvis det er ett eller annet dere lyrer på så ta det med til høstseminaret og ta det opp med Ton han er en ekspert på intrinsic muskler han var dessuten også til stedet på Judy sin workshop

og han var heller ikke enig i alt Judy sa. Så det kan bli en fin diskusjon på høstseminaret hvis dere tar opp de tingene dere lyrer og tviler på. I løp av dette referatet kommer det bli en liten miks av noen norske og engelske ord. Men det burde ikke være noe problem for forståeligheten tror jeg. I så fall ta det opp på høstseminaret. Bildene og al engelsk tekst er tatt fra CD rommen Primal pictures Ineractive hand Extensor apparatus = dorsal apparatus: The extensor apparatus is a system of precisely orientated fibers in a continuum. The extensor apparatus is also known as the extensor expansion, the dorsal digital expansion and the extensor aponeurosis or hood. All of these terms lack precise boundaries. Tendinous contributions The extensor apparatus receives the insertion of four tendons; Common extensor tendon (comprising of extensor digitorum along with extensor indicis, on the index finger, and extensor digiti minimi, on the little), Two interossei muscles, A lumbrical muscle on the radial side. Fibers of the common extensor tendon course distally radiating out, proximal to the PIP joint, towards three tendinous insertions (one middle and two lateral conjoined extensor tendons). The interossei (together with a lumbrical on the radial side of each finger) form the lateral tendons of the extensor apparatus. These give rise to a radiating fan of fibers; the transverse, oblique and lateral tendon fibers proper. Internal components: Within the apparatus, each tendinous contribution separates to act at the two interphalangeal joints. The separation and rejoining of these fibers results in the formation of a number of components; - A middle conjoined extensor tendon, - Two lateral conjoined extensor tendons, - A terminal conjoined extensor tendon. Central fibers of the common extensor tendon cross the PIP joint receiving medially radiating fibers from each lateral tendon to become the middle conjoined extensor tendon. This tendon inserts dorsally into the base of the middle phalanx. Lateral fibers of the common extensor tendon pass on either side of the middle conjoined extensor tendon joining with fibers of the lateral tendons to form two lateral conjoined extensor tendons. The lateral conjoined extensor tendons are joined by fibers from Landsmeer's oblique retinacular ligaments, fusing to form the terminal conjoined extensor tendon. This singular

tendon crosses the dorsal surface of the DIP joint to insert into the base of the distal phalanx. Retinacular structures In addition, some fibers joining the apparatus have a purely retinacular (retaining) role; - Sagittal bands at the MP joint, - Landsmeer's transverse retinacular ligaments at the PIP joint, - Landsmeer's oblique retinacular ligament. The sagittal bands at the MP joint and Landsmeer's transverse retinacular ligaments at the PIP joint act to prevent lateral displacement of the extensor apparatus. Landsmeer's oblique retinacular ligament assists in the control of synchronous movement at the PIP and DIP joints by anchoring the distal part of the extensor apparatus to a fixed point palmar to the axis of the PIP joint. The effect of this is to allow the distal extensor apparatus to glide distally as the PIP joint flexes. When the PIP joint flexes, the lateral conjoined extensor tendons of the extensor apparatus move laterally under the action of Landsmeer's transverse retinacular ligaments. Clinical Text The extensor apparatus of the finger is an intricately balanced blending of the extrinsic and intrinsic extension forces of the finger. Therefore it is common that injuries to the extensor apparatus, or injury/tightness of the muscles whose tendons contribute to the extensor apparatus will alter the balanced motion of the finger. Imbalance of motion can be caused by: Avulsion or laceration of part of the extensor apparatus. The common resulting deformities are: Mallet Finger Boutonniere Deformity Adherence of part of the extensor apparatus. This is commonly seen following immobilization for an underlying fracture or repaired tendon laceration. In these cases the tendinous fibers of the extensor mechanism become adherent to underlying bone and/or overlying skin and cannot glide. Limited glide of the apparatus then effects the transmission of tension along the system to the more distal joints. This circumstance often leads to flexion contractures of the PIP joint. Adherence of the extensor apparatus can also lead to limitation of active flexion at the PIP joint. Dorsal eller ekstensor apparatus består av: - Extensor Digitorum Communis EDC - Central slip - Lateral/sagittal bands This retaining tissue is a fibrous sheet between the common extensor tendon and lateral aspects of the volar plate of the metacarpophalangeal joint. As part of the extensor apparatus, it retains the extensor tendon over the dorsum of the metacarpophalangeal joint while permitting longitudinal excursion of that tendon due to a bucket handle type of motion of the sagittal bands. As the extensor digitorum tendon glides distally, the sagittal band slackens, allowing flexion of the MP joint. As the common extensor

tendon glides proximally, force is transmitted through the sagittal bands to lift the base of the proximal phalanx into extension, all the while maintaining the common extensor centrally over the MP joint. - Transvers interosseus fibers (MP fleksjon) The tendons of the interossei on the ulnar side of the digits and the interossei and lumbricales on the radial side form a lateral tendon on each side of the extensor apparatus. Each lateral tendon courses distally giving rise to a radiating fan of fibers; the transverse, oblique and lateral tendon fibers proper. Transverse fibers pass dorsally, meeting the extensor tendon fibers at right angles. Some of the more superficial transverse fibers interdigitate with fibers of the opposite side. Through the transverse interosseous fibers the interosseous muscles assist in stabilizing the extensor digitorum tendon at the metacarpophalangeal joint, performing a function similar to that of the sagittal bands. - Oblique fibers (PIP ekstensjon) The tendons of the interossei on the ulnar side of the digits and the interossei and lumbricales on the radial side form a lateral tendon on each side of the extensor apparatus. Each lateral tendon courses distally giving rise to a radiating fan of fibers; the transverse, oblique and lateral tendon fibers proper. Oblique fibers radiate towards the midline of the digit merging with fibers of the middle conjoined extensor tendon. Some of the more superficial oblique fibers interdigitate with fibers of the opposite side. Through the oblique interosseous fibers the interosseous muscles assist in stabilizing the extensor digitorum tendon over the proximal phalanx. - Conjoined lateral bands - Triangular ligament (keeps terminal tendon from spreading too much) The triangular ligament is formed by flimsy transverse fibers between the lateral conjoined extensor tendons over the proximal part of the middle phalanx. The fibers continue laterally as the transverse band of Landsmeer's retinacular ligament. This ligament is a fascial layer at the dorsum of the middle phalanx and the middle conjoined extensor tendon (central slip) which attaches to the bone at its base. It prevents excessive volar subluxation of the conjoined lateral bands with flexion of the middle phalanx. If the triangular ligament is lacerated or injured, this is a zone II extensor tendon injury, which results in a mallet finger deformity.

Transvers retinacular ligament Landsmeer s retinacular ligament: transverse band This is one of the retaining ligaments of the extensor apparatus. Its function at the PIP joint is similar to the sagittal bands at the MP joint, namely to stabilize the tendinous fibers of the extensor apparatus on the dorsum of the PIP joint. This wide ligamentous sheet lies lateral to the proximal interphalangeal joint and passes from the lateral margin of the lateral conjoined extensor tendon to the lateral aspect of the volar plate and C1 pulley. When the PIP joint flexes, the lateral conjoined extensor tendons of the extensor apparatus move laterally because of Landsmeer's transverse retinacular ligaments. De Extensor Digitorum Communis EDC: - Primært en MP ekstensor via de sagitale bånd. - Sekundær en PIP ekstensor. Den gir bare PIP ekstensjon når MP er ekstendert eller når MP er blokkert. - Jobber sammen med intrinsik musculatur. - Tar opp slark i de dorsal apparatus. - Kontraktur av EDC gir MP ekstensjon. Interosseus muscles: - Primært MP fleksjon og add/abduksjon. - Sekundært IP ekstesnjon (PIP mer enn DIP) - Her finnes det veldig store individuelle forskjeller. - De fyller opp rommet mellom metacarpalene. - Ødem i hånden påvirker interosseus musklene veldig mye. Ødem begrenser deres kontraksjons mulighet. (lumbricalene er mindre påvirket av ødem i hånden). - Interosseus musklene er sterkere enn lumbrikalene. - Kontraktur i interossei musklene gir IP ekstensjon. - Dorsal interossei muscles: The four dorsal interossei abduct the fingers relative to the midline of the middle finger. Through their attachments to the extensor apparatuses they contribute to flexion of the MP and extension of PIP and DIP joints. They also have a role in isolated rotation of a digit.

- Volar interossei muscles: The three volar interossei adduct the fingers relative to the midline of the long finger. Through their attachments to the extensor apparatuses they contribute to flexion of the MP and extension of PIP and DIP joints. They also have a role in isolated rotation of a digit. Dette er ganske svake muskler siden de har sin insersjon på en senestruktur og ikke på en knokkel. - Normal finger fleksjon krever interosseus elongation. - Ved en isolert IP ledd skade for eksempel en dislokasjon får man automatisk en interosseus tightness som resulterer i en redusert finger fleksjon og begrenset MP ekstensjon. - Dette betyr at man må teste interosseus tightness og dette er forskjellig fra intrinsic tightness. Interosseus tightness test: 1. flex MP joint and passive flex the PIP joint and measure the PIP flexion. 2. Passive hyperextend the MP joint and passive flex the PIP joint and measure PIP fexion. This is a tresshold test: it s less or not MEN!!! Hvor mye MP ekstension skal det være. Det er jo mange som kan overstrekke MP leddene sine bade aktive og passive. Dette som følge av IMES (Interosseus Muscle Elasticity Score). Og dette må man ta hensyn til når man skal måle interosseus tightness. HVORDAN: Man holder PIP i maksimum fleksjon mens man langsomt bringer MP leddene i passive ekstensjon. Man går så langt man kan uten å miste den maksimale PIP fleksjonen. Dette er MP ekstensjonen man skal sette MP leddene i når man skal måle interosseus tightness. MPº + PIPº = score I tilfelle av en skadet hånd: Injuried score Normal score = % of normal IMES Eksempel: Frisk hånd PIP 110º MP 17º = 127º Skadet hånd PIP 70º MP 8º = 78º 8º < 17º = interosseus thightness

78 127 = 59,8% av normal IMES Man kan gå utefra at neste hver skadet hånd har en Interosseus tightness unless the opposite has been proved. Treatment to reduce interosseus muscle tightness: - Det er en forskjell mellom en radial og en ulnar interosseus tightness. - Radial deviasjon krever lengthening av de ulnare interossei. - Ulnar deviasjon krever lengthening av de radial interossei. - De radiale interossei tillater mer lengthening enn de ulnare. Vi kan ulnar deviere MP leddene mer enn radial deviere. - Ulnar deviasjon ved RA har som regel kontraktur i ulnar interossei. - Dette kan testes mens man måler IMES (flex PIP, hyprex MP) og devier MP leddene sakte ulnar og radial. Judy Colditz foretrekker å bruke North Coast Medical sin goniometer NC 70117 Lumbricals:

The belly arises from the profundus tendon Usually the first and second lumbricales are unipennate and the third and fourth bipennate but variations can occur. Distal Attachments: To the lateral side of the extensor apparatus of the middle finger. Both attachments of the lumbrical are mobile and the individual muscle fibers are long and orientated longitudinally, suggesting a considerable excursion. The innervation of the lumbricales is variable. The ulnar nerve may supply the second and first lumbricales either in conjunction with the median nerve or alone. Actions: These depend on the degree of flexion/extension of the digits at the time the lumbricales act. The lumbricales have a direct role in extension of the proximal and distal interphalangeal joints, and add to other flexion forces at the MP joints. As the muscle contracts, traction on the proximal attachment will tend to pull flexor digitorum profundus distally, relaxing flexion. Traction on the distal attachment will tend to extend the interphalangeal joints (and flex the MP joints). The net effect is to move the finger from a flexed claw position of MP extension or hyperextension and IP flexion ( Intrinsic minus ) towards a posture of MP flexion and interphalangeal extension ( Intrinsic plus ). The net effect on the finger tip (being opposed to the thumb) would be to change a nail- topulp pinch to a pulp-to-pulp pinch. Actions: Extension of the interphalangeal joints while flexing the MP joints: The moving origin of the lumbricales (the profundus) creates a complicated biomechanical interplay of muscle forces which varies based on the position of the digit: The lumbricales have a direct role in extension of the proximal and distal interphalangeal joints, and add to other flexion forces at the MP joints. As the lumbrical contracts, traction on the proximal attachment will tend to pull flexor digitorum profundus distally, relaxing flexion force across the IP's. Concurrent traction on the distal attachment via muscle contraction extends the interphalangeal joints (and flex the MP joints). The net effect is the ability of the lumbrical to move the finger from a flexed claw position of MP extension or hyperextension and IP flexion ('Intrinsic minus') towards a posture of MP flexion and interphalangeal extension ('Intrinsic plus'). This biomechanic interplay has two suggested functions: 1. A proprioreceptive link between the flexor and extensor tendon systems. 2. A mechanical link (mobile moderator band) alternating posture. Dette er lange tynne muskler (a worm). - Origin: profundus tendon (ring and little bipennate).

- Insert: radial lateral band. - Normal function: originate on a moving tendon connecting flexor and extensors (muscles som går i to opposite directions) able to relax its own antagonist!!! - Lumbricals er jobb hestene i ekstensor apparatet. - Primær IP ekstensjon (DIP mer enn PIP) - Den drar profundus distalt helt til det er nok slakk og da strekker den IP. - Elongation during flexion. - Lumbrical shortening test: is an active test make a fist è less DIP flexion active IP flexion with MP flexed è observe DIP è paradox extension as flexion is attempted NO active DIP flexion with MP and PIP in flexion, but OK active DIP flexion with MP in extension. Recommendations for hand therapists: - For elongation of interossei and lumbrical: è Block MP in hyper extension!!! - Passive ROM doesn t stretch the lumbricals it needs the profundus. - Lumbricals need to be tested active, the elongate active Som du kanskje ser via dette referatet var det en veldig intens workshop og ikke alltid like lett å henge med. Jeg har prøvd så godt jeg kunne formidle det Judy sa på workshoppen hennes. MEN jeg kan ikke garantere at alt som står her er helt riktig og fullstendig. Så ikke ta for gitt alt jeg skrev og les det veldig kritisk. Der jeg synes det var pratisk med lit anatomisk oppfriskning har jeg hentet bilder og tekst fra Judy s CD the interactive hand.