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Chapter: Medicine Study Notes : Musculo-Skeletal

Fore arm and Hand

Don‟t number fingers, name them: thumb, index, middle, ring and little

Fore arm and Hand

 

Exam

 

·        Naming:

o  Don‟t number fingers, name them: thumb, index, middle, ring and little

o  Don‟t describe structures as medial or lateral, use radial and ulnar

o  Palmar surface of hand = volar

·        Always examine whole hand and compare with other hand

·        Inspection:

o  Work from wrist to finger tips

o  Fingers: ulnar deviation, palmar subluxation, joint swelling

o  Nails: 

§  Psoriasis: pitting (small depressions in the nails), oncyholysis (white across distal, lateral or proximal portion), hyperkeratosis (thickening of the nail), transverse nail ridges („tide marks‟        signs of previous inflammation)

§  Splinter haemorrhages in rheumatoid arthritis and SLE

§  Rheumatoid vasculitis: small, periungual brown spots

§  Periungual telangiectases in SLE, erythematosus and scleroderma

·        Palpation and passive movement together: tenderness, swelling, osteophytes, laxity

·        Function:

o  Grip strength: squeeze two fingers.  Squeeze a partly inflated sphygmomanometer

o  Key grip: try and pull thumb and forefinger apart

o  Opposition: try and pull thumb and little finger apart

o  Functional test: undo a button, write with a pen

·        Testing nerves:

o  Want to test intrinsic muscles that have no extrinsic help

o  Ulnar Nerve (Medial cord, C8, T1)

§  Abductor of little finger 

§  Adductor pollicis: grip paper between thumb and side of index finger and try and pull it away.

§  If they bend the thumb, they‟re trying to use flexors to help (ie fail the test)

§  Lumbriacls: flex MCP and extend IP joints.  Ulnar does ring and little finger 

§  Ulnar claw hand: hyperextend the fingers and the ring and little fingers curve forward due to lack of lumbriacls

o  Median Nerve (Lateral and Median Cords, C6,7,8,T1):

 

§  Opposition of thumb to little finger: requires median eminence. NB opposition of the thumb requires flexion, abduction and rotation

 

§  Abduction of thumb: Abductor pollicis brevis and longus (other two muscles of thenar eminence can be ulnar)

 

§  Anterior Interosseus Nerve Compression: compressed under the fibrous origin of flexor digitorum ® weakness of FPL, pronator quadratus and flexor profundus to the index and middle fingers ® „Benediction Hand‟ when they try and make a fist.

 

o  Radial Nerve (posterior cord, C5,6,7,8):

 

§  Check back of first web space (between thumb and index finger). Only sensory area reliably supplied by radial nerve

§  Motor distribution:

·        Upper arm: triceps

 

·        Proximal to supinator, this branch innervates ECRL, ECRB, brachioradialis, supinator · Distal to supinator tunnel: EI, ECU, APL, EPL, EPB


·        Posterior Interosseus nerve compression: passing through supinator muscle. Weakness of the long finger extensors, short and long thumb extensors but no sensory loss.

 

§  Sensory distribution: Terminal part supplies the dorsum of the hand. Posterior Cutaneous branch supplies a variable area on the back of the arm and forearm

 

§  Common sites affected: axilla (eg pressure from crutches), midhumeral fracture, at and below the elbow (dislocations and Monteggia fractures)

·        Testing ligaments:

 

o  Ligaments: test like knee. Opening to the sides, forward and posterior displacement when fully flexed and then when not quite fully flexed

o  Of flexor pollicis longus: hold proximal phalanx of thumb and flex the end


·        Of flexor digitorum profundus: hold middle phalanx and flex distal phalanx

 

·        Of flexor digitorum superficialis: hold other fingers in full extension, hold proximal phalanx of middle finger, flex finger and distal phalanx should be floppy

 

·        Of extensor pollicis longus: can rupture after a Collies fracture ® can‟t straighten distal thumb (Mallet Thumb)

 

·        Napier‟s ligament: anterior over the 1st CMC joint

 

Injuries

 

·        Fractures of Radius and Ulna:

 

o   Mechanism: occur commonly in road accidents, direct blow causes transverse at same level. Twisting may cause spiral or oblique fractures at different levels

 

o   Clinical: Fracture usually obvious. Pulse must be felt and hand examined for circulatory or neural defects.


o   Treatment: Kids only need cast for 6-8 weeks. Adults often require internal fixation.

 

o   Fractures of either the radius or ulna alone, with shortening (ie angulation or displacement) are associated with dislocation of the other:

§  Monteggia Fracture:

·        Fracture to ulna and dislocation of radial head

·        Mechanism: fall on hand, body twisting at time of impact 

·        Clinical: Ulnar deformity obvious, but dislocation may be masked by swelling. Look for pain and swelling on lateral side of elbow. Wrist and hand must be examined for signs of injury to radial nerve 

·        Treatment: Restore length to ulna then reduce. Above elbow cast, arm at 90 degrees flexion 6 weeks

§  Galeazzi Fracture:

·        Fractured radius and subluxation or dislocation of distal radio-ulnar joint

·        Clinical: more common than Monteggia, important to check for ulnar nerve injury

·        Treatment: As for Monteggia

o   Colles' Fracture:

 

§  Fracture of the radius within 2.5cm of the wrist with dorsal angulation/displacement. If displacement occurs the classic dinner fork deformity occurs.

 

§  Mechanism: Most common fracture resulting from a fall on the outstretched hand. Sometimes TFCC (Triangular Fibrocartilage Complex) is torn therefore disrupting the distal R-U joint and causing ulnar angulation also

 

§  Clinical: Pain and tenderness over distal end of radius after a fall. Deformity and radiology also often definitive

 

§  Treatment: If displaced then reduce, plaster cast in ulnar deviation and slight flexion for 5-6 weeks with finger and wrist exercises

 

§  Complications: Radial drift or ulna prominence in mal union. Delayed rupture of tendon of extensor pollicis longus due to roughness at site of injury or decreased blood supply (® Mallet thumb). Carpal tunnel syndrome also possible

 

o   Smith‟s Fracture: Due to fall on the back of hand. Reverse of Colles fracture (ie volar displacement rather than dorsal)

o   Barton‟s Fracture: Intra-articular fracture of the distal radius.  Unstable

·        Distal Radio-ulnar joint:

o   Triangular ligament (TFCC): holds radius in place while it rotates around the ulnar

 

o   Test for dislocation: grip around the proximal wrist and squeeze or supinate ® pain

·        Scaphoid fractures:

o   Rare in skeletally immature children

o   2nd in occurrence to radial fracture – usually young adult males

o   Waist of scaffoid the most common site

 

o   Caused by fall on radial side of outstretched hand ® land on tubercle of the scaffoid with wrist hyper-extension

 

o   Blood supply is distal to proximal pole Þ prone to avascular necrosis or poor healing

 

o   If suspected treat as a fracture, immobilise joints above and below (i.e. Collies cast, with thumb free, up to 10 weeks to healing) – may not see it on first Xray and prone to non-union. Can see on bone scan after about 1 day. However, over diagnosed.

·        Carpal dislocations:

 

o  Perilunate dislocation: associated with distal radius fracture. Lunate stays attached to radius, all other carpals pushed dorsally

o  Trans-scaphoid perilunate dislocation: as for perilunate dislocation, but fracture through the waist

o   of the scaphoid leaves the proximal fragment in place.  Treatment: reduction/surgery

·        Metacarpal Fractures:

o  5th most common.  Treatment: Buddy strapping, or strapping + slab

o  1st metacarpal: Bennett‟s Fracture – through middle of the metacarpal and intra-articular through the 1st CMC joint. Following a fall or blow on a clenched fist or forced abduction of the thumb (skiers). Ligament of Napier can commonly be injured as well. Unstable as oblique and proximal fragment is attached to trapezium and distal fragment has strong muscles attached to it that pull it proximally. Reduce and plaster with thumb held abducted and extended. Transverse fracture is straightforward: Scaphoid cast

 

o  Multiple metacarpal fractures: twisting and crush injuries. Realignment with Kirschner wires or small bone plate

·        MCP dislocation.  Uncommon.  May require open reduction

·        Finger injuries:

 

o  Mallet Finger: can‟t extend DIP: rupture or avulsion of extensor tendon, eg by ball hitting outstretched finger. If < one month since injury then splint in extension otherwise surgery (but may not get full flexion back)

 

o  Button Hole (Boutonniere) Deformity: can‟t extend PIP joint of finger and hyperextension of DIP:

 

o   Rupture/detachment of central slip of extensor tendon with lateral bands slipping down the side of the finger

 

o  Trigger Finger (Stenosing Tenosynovitis): flexor tendon inflames and then jams going through the A1 annular pulley over the MP joint (under the palmar crease). May find crepitus, swelling, triggering and tenderness. Common in RA. Treatment: cut the A1 pulley

 

o  De Quervain‟s Syndrome. Pain over the styloid process of the radius (dorsal wrist). Finckelstein‟s sign: pain on forcible adduction and flexion of the thumb into the palm. Stenosing tenosynovitis/inflamed tendon sheath of extensor pollicis brevis and abductor pollicis longus. Management: Rest, NSAIDs, cortisone injection, surgery

 

o  Skiers/Gamekeeper‟s Thumb: rupture of the ulnar collateral ligament of the MCP joint of the thumb, caused by forced abduction. If stable then splint. If unstable (can‟t oppose fingers) then repair (adductor tendon may get in the way and prevent reattachment)

 

o  Dislocation of the phalanges: usually always ligament injury as well. Swelling may take up to 2 years to reduce. Reduction can be spontaneous or via longitudinal traction. Buddy strapping + early mobilisation

 

o  Phalangeal fractures: Buddy taping: encourage flexion, deny rotation, allow for swelling (ie not too tight)

 

·        Dupuytren‟s Contracture: Painless fibrosis of the palmar aponneurosis (can also occur on the foot). Usually familial (associations with alcoholism and manual work over-rated), anti-epileptics. Causes puckering of the skin over the distal palmar crease and gradual flexion of the fingers (usually starts with ring finger). Treatment conservative. If they can‟t push their palmer MCP joints into the table then consider surgical release. Prognosis worse if younger

 

·        Ganglia: Painless, jelly filled swelling caused by a partial tear or bulging of a joint capsule. Commonly in the wrist. May resolve or cause little trouble. Don‟t respond to injection. Surgical excision.

 

Carpal Tunnel Syndrome

 

·        Compression of the median nerve as it passes through the carpal tunnel in the wrist

·        Epidemiology: Common.  Usually women 3 - 50 years

·        Causes: Due to thickened tendons or synovitis in the carpal tunnel

o  Rheumatoid arthritis

o  Hypothyroidism

o  Acromegaly

o  Pregnancy (2ndary to oedema)

o  Obesity

o  Amyloid

o  Diabetes Mellitus

o  Idiopathic

 

·        Symptoms: Pain/tingling in the hand and wrist classically in the median nerve distribution (palm and thumb, index and middle fingers). Wakes at night, shakes hand, can‟t get it comfortable

·        Signs:

o   Wasting of thenar eminence, weak thumb abduction and opposition (late signs).

o   Tinel‟s Test: pain is reproduced by tapping a tendon hammer over the carpel tunnel

o   Flex both wrists for 30 seconds – may precipitate paraesthesia if carpal tunnel syndrome: Phalen‟s

o   Test

·        Investigations: median nerve conduction velocity test

·        Treatment:

o   Light splint to hold wrist in slight dorsiflexion, NSAIDs and vitamin B6

o   Diuretics

o   Corticosteroid injection

o   Surgical Decompression

 

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Medicine Study Notes : Musculo-Skeletal : Fore arm and Hand |


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