O&T SC062: I Cut My Finger: Hand Injury, Industrial Safety And Compensation

Question 1

Anatomy of hand

Answer 1

High demand for function

Prone to complicated injuries:
1. Contact to outside world
2. Different varieties of work
3. Complex anatomy

4 important anatomic tissue layers:
1. Skin + SC tissue + Vascular structures (Circulation)
2. Nerve (Sensation)
3. Muscle + Tendon (Active movement)
4. Bone + Joint (Passive movement)
Rehabilitation damands ***gliding of tissue layers (not stick together)

Volar side:
1. Bone
2. Muscle (Intrinsic)
3. Tendon (Flexor tendons of extrinsic muscles)
4. Joints (Synovium)
5. Peripheral nerves

Dorsal side:
1. Tendon (Extensor tendons of extrinsic muscles)

Question 2

Classification of Hand injuries

Answer 2

1. Closed (usually blunt injury, no immediate risk of infection, can wait)
   - Fracture
   - Dislocation
   - Tendon avulsion (e.g. mallet finger)
2. Open
   - Sharp cut —> Skin, SC tissue, ***Neurovascular bundle (check motor + sensory), Tendon, Bone, Amputation
   - Crush

Question 3

Finger tip injury

Answer 3

Small: Keep wound clean to allow spontaneous healing
Large: Wound coverage + repair

Question 4

Urgent management of amputated part

Answer 4

1. Remove amputated part atraumatically to prevent further tissue trauma (e.g. if trapped under bus) —> preserve as much as possible
2. Wrap in sterile gauze (if available) with saline
3. Put in plastic bag
4. Submerged in ice cold water (4oC) to decrease warm ischaemic time (limit to 6 hours for parts with muscles) (X ice: ∵ water content in finger expand —> cell membrane damage)

Question 5

Types of injuries

Answer 5

1. Sharp cuts
   - Usually circulation is good except amputation
   - Not too much damaged tissue —> not much fibrosis (undesirable: impair mobility)
2. Crush injury
   - Much devitalisation (a lot of dead cells in injured part)
   - Result in fibrosis
   —> Relatively poorer outcome than sharp cut injury

Other types:
3. Burnt (flame, scald, electrical, chemical)
4. Frostbite

Question 6

***Approach in Hand injury (History taking, P/E)

Answer 6

Severe life-threatening injury before less severe injury (hand injury alone often not life-threatening)

History:
1. How to get the injury?
2. When
3. Associated injury
4. Relevant medical history + medication

P/E:
1. Inspection
- External wound
- Deformity / Abnormal posture (indicate bone, tendon, joint injury)

2. Palpation
   - Temp
   - ***Pulse
3. ROM
   - Active + Passive
4. Sensation
   - Pain (Spinothalamic)
   - Light touch (Dorsal column)

Treatment:
1. Identify injuries to other body systems (multiple trauma patient)
2. Assessment of hand injuries (extent + structures involved) + Documentation
3. Determine treatment method (single stage / multiple stages)
4. Rehabilitation always

Question 7

***First aid management

Answer 7

1. ***Removal of possible limb constriction (∵ can get edematous after injury, e.g. ring, watch, bracelet) (e.g. Ribbon method)
2. ***Pressure to stop bleeding —> Direct to wound / digital artery
3. ***Clean wound with detergent + copious amount of fluid
4. ***Wound dressing
5. Bandaging + ***Splinting

Emergency medication:
1. **Tetanus + **Antibiotics prophylaxis (in open wound)
2. Analgesics

Conservative treatment:
1. Minor cut
2. Small finger tips injuries

Question 8

Treatment in Bleeding laceration

Answer 8

1. Lie patient down
2. Hand elevated
3. Sterile dressing to cover the wound
4. Gentle direct pressure applied

Finger pressure dressing:
1. Sterile dressing pack
2. Non-adherent absorbent dressing
3. Adhesive tape
4. Cotton tubular bandage
5. Applicator for cotton tubular bandage

Procedure:
- Wound toilet / suture
—> Place non-adherent dressing onto the wound
—> Place absorbent gauze to form a pressure pad
—> Apply tapes (ensure tape not complete encircle finger)
—> Selective appropriate width of cotton tubular bandage and cut a length 10x as long as injured finger
—> Thread bandage over applicator
—> Pass applicator over finger and ease off the end of bandage
—> Twist applicator around the base of finger to anchor the bandage
—> Twist applicator continuously while withdrawing it to the end of finger
—> At the end of finger twist bandage through 2 complete turns
—> Preferably tip of finger is exposed for observation of circulation
(If tip need to be covered up —> no tight circumferential taping should be applied —> split remaining piece of bandage into 2 and use the 2 ends to tie the dressing loosely in position at base of finger)

Question 9

Life threatening condition in Hand injury

Answer 9

ONLY one:
- Uncontrolled haemorrhage from a partially transected vessel (vessel does NOT spasm —> continual haemorrhage)

Emergency control of arterial bleeding:
1. Direct pressure
2. Apply arm tourniquet
3. Elevation
4. Inflating cuff of sphygmomanometer to 100-150 mmHg (above SBP)

Question 10

Subungual haematoma

Answer 10

• Nail hit by heavy object —> Very painful
• Bleeding inside soft tissue, haematoma collected underneath nail

Treatment:
Small: Resolve on its own

Moderate:
Light spirit lamp
—> Straighten out paper clip + Heat in flam until red hot
—> Apply red hot tip to central point of haematoma
—> Burn a hole in nail
—> Allow blood to escape through hole

Large: Need drainage (with incision in soft tissue / remove strip of nail)

Question 11

Open hand injuries

Answer 11

Treat as **emergencies (cleansing + operation within 6 hours —> prevent bacterial contamination / infection)
1. **Tetanus + ***Antibiotics prophylaxis

2. Assess + Documentation
3. ***Exploration
   - Adequate anaesthesia
   - Surgical toilet (copious of detergent + fluid)
4. **Repair
   - Primary repair if possible
   - Set priority if not possible (tourniquet time is limited ~2 hours)
   - **Skin coverage is highest priority to prevent infection
   - Secondary repair / reconstruction
   - Late reconstruction (for residual problem)
   —> Skin: Insufficient skin
   —> Bone: Malunion / Non-union
   —> Tendon: Adhesion
   —> Nerve: Poor regeneration
   —> Composite tissue transfer (e.g. toe hand transplant)

Rehabilitation always:
1. **Edema control
- Elevation
- Pressure dressing (e.g. Boxing glove)
2. **Immobilisation in functional position if necessary (e.g. flexed MPJ, extended IPJ, thumb abducted + extended)
3. ***Early mobilisation (ensure bone, joints, muscles, tendons are stable)
- Prevent joint stiffness of involved joints
- Maintain gliding of tissue layers
- Mobilisation of joints of whole body
- Maintain cardio-thoracic fitness
- Maintain muscle strength + endurance
4. Mental rehabilitation
- Adjustment problem
- Depression
- Body image
- Stamina to go back to original work

Question 12

Case managers for Work-related injuries

Answer 12

1. Close observation of rehabilitation
2. Arrange best rehabilitation + Follow up for patients
3. Liaise with multi-disciplines (PT, OT, MSW, Psychi, Psycho) for best patient management
4. Target to shorten duration out of work, maximise recovery

Question 13

Work-related hand injury

Answer 13

• 75% work-related injury involve hand
• Poor management leads to functional disability
• Loss of earning capacity of patient
• Decrease family income —> affect life of family

Types of work:
1. Department stores
2. Restaurants
3. Hospitals
4. Hotels
5. Motor vehicle manufacturing
6. Nursing / personal care facilities
7. Retail grocery stores
8. Trucking industries

Fatalities:
1. Construction
2. Transportation
3. Public utilities industries

Question 14

Upper limb work-related injuries

Answer 14

• More common due to chronic overuse now
• Not life-threatening but pain + decrease in work capacities
• Office workers
• ***Notifiable disease

Diseases:
- Carpal tunnel syndrome
- De Quervain’s disease
- Trigger finger
- Tennis elbow

Cause:
- Multifactorial

Question 15

Occupational safety charter

Answer 15

• Safety is a shared responsibility of employers + employees

Employers:
- Safety organisation to ensure each person’s role + responsibilities are understood
- Safety training to equip all staff with knowledge, skills, attitudes
- Risk assessment programme which identify actual + potential risks
- Safe working environment
- Healthy assurance programme
- Safety committee
- Safety promotion

Employees:
- Follow safety rules + work procedures set out in safety management system
- Take active part in attending safety + health training
- Report to employer any potential job hazards
- Make suggestions on safety improvement to supervisor / employer
- Cooperative with relevant authorities in reporting breaches of statutory requirements

Question 16

Industrial safety in high risk work

Answer 16

1. Protective shield to cover press mould
2. Safe use of electric saw
3. Research to find out causes of industrial accidents

Question 17

Compensation

Answer 17

Sick leave:
- ***80% of salary up to 3 years

Permanent disability:
- Rated according to loss of earning capacity
—> Under 40: 96 months’ earnings / minimum amount of compensation x % of PDC
—> 40-56: 72 months’ earnings / minimum amount of compensation x % of PDC
—> >56: 48 months’ earnings / minimum amount of compensation x % of PDC

Question 18

Decrease social cost of industrial accident

Answer 18

1. Government policy / law
2. Employers’ responsibility
3. Workmen’s awareness

Question 19

SpC O/T Seminar: Hand injuries
Hand injuries Case 1: Avulsed nail

Answer 19

Distal hand:
- Most prone to injury
- Volar / Dorsal injury

P/E (Nail plate + Nail bed + Distal phalanx):
1. Digit involved
2. Perforation of nailbed
- Outside-in / Inside-out injury (indicate underlying fracture fragment of distal phalanx)
—> communicate with atmosphere in open fracture
—> possible complication: Infection, Osteomyelitis

Investigations:
1. X-ray
- Comminuted fractures caused by crush injury

Treatment:
1. ***Wound management
- Proper wound care

2. **Antibiotic + **Tetanus prophylaxis

Question 20

Hand injuries: Distal phalanx fracture

Answer 20

DIP joint motion does NOT put loading on tuft fracture of distal phalanx
- Pinching will put loading to fracture fragment and should be avoided
- Active joint motion should be encouraged to prevent stiffness + continue original motor program

Question 21

Hand injuries Case 2: Volar distal injuries

Answer 21

P/E:
1. Exposed tissue?
- Tendon
- Bone

Treatment:
1. Conservative: ***Wound dressing
- if Small surface, Superficial cut
- Body can regenerate skin layer by re-epithelialisation, granulation tissue formation —> restore bulk of pulp

2. Urgency to cover (otherwise may be desiccated —> necrotic)
   - if Large surface, Deep cut
   - Skin layer most important to replenish for protective surface for exposed tendons / bones
   - **Skin graft / **Skin flap (with skin, SC tissue, blood supply, nerve supply)
   —> V-Y plasty (for transverse cut)
   —> Volar advancement flap for thumb
   —> Flap from dorsum of index finger to thumb tip defect —> index finger defect then covered with skin graft
   —> Partial toe transfer (need arterial, venous, nerve anastomosis)
3. Debridement of dead tissue + Suturing of viable tissue

Question 22

Nerve problems Case 3: Carpal tunnel syndrome

Answer 22

Most common nerve problem: **Nerve entrapment
Most common nerve entrapment in upper limb: **Carpal tunnel syndrome

History:
1. Middle age women
2. Repetitive stress injury
3. ***Worse at night (∵ accumulation of interstitial fluid at night)
4. Numbness + Clumsiness in hand

Causes:
1. **Overuse (majority)
2. Local causes: **Fracture, Dislocation, **Space-occupying lesion (e.g. gouty tophi)
3. General causes: **Myxedema, ***Amyloidosis in chronic renal failure
(4. Pregnancy?)

P/E:
Motor:
1. Atrophy / Weakness of thenar muscles
- only **abduction is affected (i.e. Abductor pollicis brevis) (∵ Flexor pollicis brevis, Opponens pollicis may be innervated by **Ulnar nerve)
- indicate chronic —> motor fibres also involved

2. Supinated posture of thumb (***Adducted thumb)
   - indicate chronic —> motor fibres also involved

Sensation
3. Decreased sensation of radial 3.5 fingers

4. ***Palm spared
   - ∵ palmar cutaneous nerve not enter carpal tunnel
5. **Tinel’s sign positive
   - tap on median nerve in carpal tunnel —> numbness over radial 3.5 fingers —> ∵ median nerve compressed —> axons become necrotic —> **regeneration of nerve endings —> local sensitivity of median nerve over carpal tunnel —> tap on nerve endings —> sensitive
6. ***Phalen’s test positive
   - palmar flex wrist —> kinking of median nerve

Treatment:
1. Conservative (***Splint at night time —> keep median nerve in smooth course)
- early cases (only numbness)

2. Surgery (Open / Endoscopic release)
   - advanced case

Question 23

Nerve problems Case 4: Ulnar nerve neuropathy

Answer 23

Causes:
1. **Cubital tunnel syndrome (most common)
2. **Tardive ulnar nerve palsy (valgus deformity of elbow stretching ulnar nerve)
3. ***Subluxable ulnar nerve with frictional injury

P/E:
Motor:
1. Thenar: Froment’s sign positive
- Weak **Adductor pollicis —> need to compensate by flexion of IP of thumb (*Flexor pollicis longus by Median nerve) to pinch paper

2. Hypothenar: ***Hypothenar atrophy
   - Weak hypothenar muscles
   —> Weak abductor digiti minimi
3. Lumbricals: ***Ulnar claw hand
   (- Unopposed long extensor at MCP by Radial nerve
   - Unopposed long flexors at IP by Median nerve)
4. Interossei: ***Web space muscle atrophy
   - Weak adduction of fingers (test by gripping paper between fingers)
   - Weak abduction of fingers (by spreading fingers apart) (Weak 1st dorsal interossei)

Sensory:
1. Ulnar 1.5 fingers with corresponding area of palm + hand dorsum

Treatment:
- **Surgery mainly (not much room for Conservative)
—> **Decompression (open / endoscopic)
—> **Anterior transposition of ulnar nerve (move ulnar nerve to volar side of elbow joint to decrease tension + release compression)
—> **Medial epicondylectomy

Question 24

Nerve problems Case 5: Radial nerve compression

Answer 24

Radial nerve palsy (aka Saturday night palsy)

Causes:
- **Displaced fracture of humerus
- **Falling asleep with one’s arm hanging over the arm rest of a chair —> Compression of radial nerve

P/E:
Motor:
1. ***Drop wrist + Drop finger (MCPJ)
- Weak wrist extensors
- Weak long finger + thumb extensors by testing extension at MCPJ (NOT IPJ —> ∵ supplied by intrinsic muscle by ulnar nerve)

Sensation:
2. ↓ Sensation at ***anatomical snuffbox (but much overlapped by median nerve —> ∴ small area of deficit)

Treatment:
- **Splintage to lift up fingers and wrist while waiting for recovery of radial nerve
- Iatrogenic / Laceration wound: **Exploration + Repair
- Humerus fracture: ***Monitor (mostly Neurapraxia: 90% recover)
- Radial tunnel syndrome (Entrapment neuropathy): Rare

Question 25

Hand rehabilitation

Answer 25

Regain maximal function after injury / illness
1. Start at ***time of injury —> Prevent edema (∵ edema fluid induce adhesion between tissue layers)
2. Encourage gliding of tissue layers to prevent adhesion
3. Passive mobilisation whenever safe
4. Active mobilisation whenever safe

Severe hand edema:
- Volar tissue are bound to deeper tissue by fascial layer so edema cannot occur
—> Fluid collected in **dorsum of hand + digits
—> **Claw hand deformity (MPJ extended, IPJ flexed, Thumb adducted)
—> Non-functional (∵ space of motion very limited)

Role of treating surgeon / hand therapist:
- Good operation + Good rehabilitation —> Good outcome

Early phase:
1. Edema control
- **Compression Boxing glove —> **Functional position of hand: MPJ flexed, IPJ extended, Thumb abducted to open up 1st web (exactly opposite to Claw hand)
- ***Elevation of hand

2. Protect damaged tissue + Improve function during recovery phase
   - ***Splintage to lift up fingers and wrist while waiting for recovery of radial nerve
3. Maintain gliding of tissue layers
4. Active / Passive / Dynamic passive motion of mobilisation to maintain gliding of tissue layers

Late phase (after recovery of damaged tissue):
1. Sensory / Motor re-education

2. Strengthening exercise + Work hardening
   - e.g. Carpal tunnel syndrome: hand and wrist exercise to increase nerve mobility + active ROM + strength of hand / upper limb
3. Work rehabilitation
   - Train up tasks of their job demand

Management of claw hand:
- Vigorous mobilisation execise

Question 26

Miscellaneous common conditions: Dinner fork deformity

Answer 26

***Colles fracture:
- Osteoporosis
- Elderly
- Fall on outstretched hand

Distal fracture fragment:
1. Dorsal angulation + displacement
2. Radial angulation + displacement
3. Shortening of radius

Treatment:
- Extra-articular fracture: Conservative with CR + POP

Question 27

Miscellaneous common conditions: Scaphoid fracture

Answer 27

Causes:
- Falling on outstretched hand

Scaphoid:
- Blood supply from dorsal scaphoid to proximal scaphoid (retrograde bloodflow)
—> Fracture
—> Proximal part of scaphoid will lack blood supply
—> Must have fracture healing in order to regain blood supply to proximal pole
—> Risk of ***AVN of proximal part of Scaphoid (if fracture not treated properly / no fracture healing)

Clinical features:
1. Local tenderness at **anatomical snuffbox + **scaphoid tubercle (Classical sign: but can also appear in sprained wrist)
Other signs not reliable:
2. Pain over scaphoid area on radial-dorsiflexion (impingement of scaphoid)
3. Pain on forced radial-dorsiflexion + forced ulnar deviation
4. Pain over scaphoid when patient pinches thumb against index finger while examiner tries to pull against it

Management:
1. ***MUST identify the fracture (esp. in undisplaced fracture)
- X-ray may not show fracture initially —> require CT / MRI

2. Immobilise wrist with ***Scaphoid cast
   - to avoid displacement of fracture
   - treat as displaced fracture if cannot see on X-ray

Question 28

Miscellaneous common conditions: De Quervain’s disease

Answer 28

Inflammation of tendon in ***1st extensor compartment —> APL + EPB

Causes:
1. Excessive use of thumb
2. Sustained posture in lifting heavy objects
—> Overuse of tendon —> Inflamed

S/S:
- Pain over radial styloid —> ***Finkelstein test positive
—> Put thumb and hold it in hand then ulnar deviate wrist
- Pain in both wrist neutral and flexed position during active extension and abduction of thumb against resistance

Treatment:
1. Conservative
- NSAID
- Splint

Question 29

Miscellaneous common conditions: Mallet finger deformity and Boutonniere deformity

Answer 29

Mallet finger deformity:
- Most common extensor injury
- **Hyperflexion injury of DIP during ballgames (篤魚蛋)
—> Rupture of **distal extensor tendon

Treatment:
1. ***Mallet finger splint: Oppose tendon ends in normal position
2. Mobilisation exercise after recovery

Prognosis:
- Healing in 6 weeks

Boutonniere deformity:
- Rupture central slip of extensor system
- Treatment: Long mallet splint / Surgery

Question 30

Miscellaneous common conditions: Loss of flexor tone

Answer 30

Normal hand posture: Flexor tone predominant —> flexed digits

Loss of flexor tone: Flexor problem (Flexor digitorum superficialis + profundus)

Question 31

SpC O/T Seminar: Peripheral nerve injuries
Structure of nerve + Nerve injury types

Answer 31

Epineurium:
- Covering peripheral nerve
- Cushion against external pressure

Perineurium:
- Around one fascicle
- Tensile strength and elasticity

Endoneurium:
- Around each axon

Nerve injury types:
1. Traumatic
- Stretching (15% elongation can already cause axonal disruption)
- Laceration
2. Compression
- Chronic compression
—> Local ischaemia + Endoneural edema + Fibrosis —> more ischaemia —> Segmental demyelination + Wallerian degeneration
—> Low threshold (30mmHg: Paresthesia, 60mmHg: Complete nerve block)
3. Vascular
4. Vibration
5. Radiation
6. Chemical / Biochemical

Neurapraxia:
- Myelin sheath (Sunderland 1)
- No Wallerian degeneration —> EMG: No muscle fibres fibrillation
- Reversible
- Full recovery
- NCS: Conduction block at lesion but distal conduction preserved

Axonotmesis:
- Axon involved (Sunderland 2)
- Have Wallerian degeneration —> EMG: Have muscle fibre fibrillation
- Variable reversibility
- Incomplete recovery
- NCS: Loss of conduction both at + distal to lesion

Neurotmesis:
- Endoneurium (Sunderland 3), Perineurium (Sunderland 4), Epineurium (Sunderland 5)
- Have Wallerian degeneration —> EMG: Have muscle fibre fibrillation
- Variable / No reversibility
- Incomplete / Poor recovery
- NCS: Loss of conduction both at + distal to lesion

Nerve fibre transection:
- Distal segment —> Wallerian degeneration —> Schwann cells proliferation + line up in bands of Bungner
- Proximal segment —> Atrophy + degeneration to nearest node of Ranvier —> Axon spouting at 1 mm/day down endoneurial tubes —> “Axonal” connection with periphery + maturation of nerve fibre

Nerve regeneration:
- Yes: advancing Tinel sign
- No: time-dependent permanent atrophic changes to target organ
—> motor end plates disappear after 3 months —> followed by muscle spindles + cutaneous sensory organs

Prognostic factors:
1. Age (most important factor)
2. Mechanism of injury
- Sharp cut better, Crush injury poorer
- Low velocity injury better, High velocity injury poorer
- Associated arterial / bony injuries poorer (poor wound environment)
3. Level of injury
- Distal better

Question 32

Nerve repair

Answer 32

1. Direct muscular neurotisation
   - inserting proximal nerve stump into affected muscle belly: resulting in less-than-normal function
2. Epineural repair
   - preparation of nerve ends (resecting neuroma / scar) —> suture epineurium together —> approximate 2 ends
   - need to ensure proper rotation + lack of tension
3. Grouped fascicular repair
   - for large nerves (e.g. Sciatic nerve)
   - suture perineurium together
   - more scarring due to more sutures
   - no significant difference in outcome compared to epineural repair

Limitations:
1. Slow growth velocity (1 mm/day)
2. Chronic denervation —> target muscle atrophy —> cannot be dealt by surgery
3. Neural atrophy only partially reversible for delayed repair
4. Misalignment of motor and sensory axons in large nerves

Other options:
4. Nerve grafting
- if defect too large to perform tension-free repair
- options:
—> **Nerve graft (Autograft e.g. Sural nerve / Allograft)
—> **Nerve conduit (act as scaffold for nerve to grow back) (Artificial e.g. silicon / Non-artificial e.g. vein graft, muscle)
5. Nerve transfer / Neurotisation
6. Gene therapy

Sural nerve: lateral side of foot, sensory only, less donor site morbidity

Question 33

Median nerve

Answer 33

Motor supply:
1. Volar forearm (Extrinsic muscles)
- PT, FCR, PL, **FDS
- **Anterior interosseous nerve (AIN) (branch off at proximal forearm): FPL, ***Radial half of FDP, PQ

2. Intrinsic muscles of hand
   - LOAF
   —> Lateral 2 lumbricals
   —> Thenar muscles (Recurrent motor branch): OP, APB, FPB

Sensory supply:
1. 3.5 fingers sensation (Common + Proper digital nerves)
2. **Thenar sensation (Palmar cutaneous branch: branches off **before entering carpal tunnel —> NOT affected in CTS)
—> ***Need to check Thenar sensation to determine whether it is CTS / Higher palsy

Common sites of compression:
1. **Pronator teres syndrome (High palsy: more functional disturbance)
2. **Carpal tunnel syndrome (Low palsy) (more common)

Causes of Median nerve palsy:
1. **Idiopathic CTS
2. **Secondary CTS
- **Trauma (e.g. **Distal radius fracture, Carpal injury, **Supracondylar humerus fracture: **AIN palsy) —> Acute CTS
- **Inflammatory joint disease (e.g. RA, Gout, Pseudogout)
- **Systemic (e.g. Myxedema, Amyloidosis)
- **SOL within carpal tunnel (e.g. Ganglion cyst, gouty tophi)
- Tenosynovitis
(- **Pregnancy
- ***Acromegaly
- Diabetic neuropathy)

Question 34

P/E of Median nerve

Answer 34

Intrinsic muscles:
1. Thenar wasting
2. Weak thumb opposition (Weak OP)
3. Weak thumb abduction (Weak APB) (a specific muscle innervated by Median nerve ONLY)

Extrinsic muscles:
4. Square sign / Failure to do OK sign
- ***AIN palsy (esp. in supracondylar fracture in children): Weak FPL + FDP
- FPS is intact —> Can flex PIP

5. Benediction sign / Cannot make a fist (Cannot flex 1 + 2 + 3 finger)
   - ***High median nerve palsy: Weak extrinsic + intrinsic muscles: FPL + Radial FDP + Radial lumbricals
   - 4 + 5th digit can flex: intact Ulnar FDP + Ulnar lumbricals
   - vs Claw hand: Cannot extend 4 + 5th finger

Provocative tests:
1. Tinel’s sign (percuss from distal to proximal)
2. Phalen test (30s)
3. Durkan’s test (direct compression test)

Differentiate high vs low palsy:
Motor:
- Intrinsic LOAF = Low (carpal tunnel)
- OK sign (FPL + FDP) = AIN
- Both = Median nerve

Sensory:
- Radial 3.5 digit = Low (carpal tunnel)
- Thenar eminence = Palmar cutaneous nerve = High (proximal to carpal tunnel)

Tinel sign:
- Area of nerve injury

Question 35

Ulnar nerve

Answer 35

Motor supply:
1. Volar forearm (Extrinsic muscles)
- FCU
- Ulnar half of FDP

2. Intrinsic muscles of hand
   - ALL except LOAF
   —> Adductor pollicis
   —> Interossei (Palmar + Dorsal)
   —> Medial 2 lumbricals
   —> Hypothenar (ADM, FDMB, ODM)

Sensory supply:
1. 1.5 fingers sensation
- Superficial terminal branch

2. Hypothenar sensation
   - **Palmar cutaneous branch: branches off **proximal to wrist —> High palsy
   - **Dorsal cutaneous branch: branches off **proximal to wrist —> High palsy

Common sites of compression:
1. **Cubital tunnel syndrome (High palsy) (more common)
- associated with Cubitus valgus, Elbow OA —> check **elbow ROM
2. ***Guyon’s canal / Ulnar tunnel syndrome / Cyclist’s palsy (Low palsy)
- chronic compression of ulnar wrist

Causes of Ulnar nerve palsy:
1. **Elbow deformity (Cubitus valgus, varus)
2. **Elbow arthritis (e.g. OA / RA elbow)
3. Entrapment neuropathy (e.g. **Cubital tunnel syndrome, **Guyon’s canal)
4. Trauma
5. Muscle anomaly

DDx:
- T1 radiculopathy (but have thenar muscle wasting)

Question 36

P/E of Ulnar nerve

Answer 36

Intrinsic muscles:
(記: Adductor pollicis, Interossei, Lumbricals, Hypothenar)
Adductor pollicis:
1. Froment’s sign
- Compensated by IPJ flexion: FPL by median nerve

2. Jeanne sign (Weak Adductor pollicis)
   - Compensated by MCP hyperextension: EPL by radial nerve

Interossei:
3. Weakness in Abduction / Adduction of fingers
- **Diamond hand sign unable to do (1st dorsal interossei (adduction): strong side push against weak side)
- **Cross finger test (1st palmar (adduction) + 2nd dorsal interossei (abduction))

Lumbricals:
4. Claw hand / Duchenne sign (Weak Lumbricals)
- **Intrinsic-extrinsic imbalance (weak intrinsic + strong extrinsic (long flexor + long extensor))
—> **MCP hyperextension (EDC by Radial nerve) + ***IP flexion (FDS by Median nerve + FDP not affected in low palsy)

Hypothenar:
5. Abductor digiti minimi (ADM)
- Push little finger against each other

6. Wartenberg sign (~finger escape sign in cervical myelopathy)
   - Little finger kept in abduction + slight extension (unopposed action of EDM by Radial nerve)
   - ***Intrinsic-extrinsic imbalance
7. Masse sign / Rectangular palm
   - Wasting of hypothenar —> flattened metacarpal arch

Extrinsic muscles:
1. Weak wrist ulnar deviation + flexion (Weak FCU)
2. Pollock test (FDP of ring + little finger —> DIP flexion)
- ***Need to immobilise PIP (FDS)

Cubital tunnel:
1. Ulnar nerve subluxation around medial epicondyle
2. Elbow flexion test
3. Tinel sign

Differentiate high vs low palsy:
Motor:
- Intrinsics = Low
- FDP (Pollock test), FCU = High

Sensory:
- Ulnar 1.5 digit = Low
- + Ulnar hand dorsum (Dorsal cutaneous branch) = High

Tinel sign:
- Area of nerve injury

**Ulnar paradox:
- High palsy = more muscles paralysed but **less clawing = actually less disabling (∵ FDP also involved in high palsy —> less clawing)

Question 37

Radial nerve

Answer 37

Motor supply:
1. Arm
- Triceps
- Anconeus

2. Elbow
   - BR
   - ECRL
   - Supinator
3. Posterior interosseous nerve (PIN) (posterior to interosseous membrane)
   - ECRB
   - EDC
   - APL / EPB
   - EPL
   - EIP
   - EDM
   - ECU

Sensory supply:
1. Posterior arm
2. Posterior forearm
3. Hand dorsum (superficial radial nerve branch)

Common sites of compression:
1. **Axilla (Saturday nigh palsy)
2. **Lateral intermuscular septum (common in Distal 1/3 **humerus fracture (Holstein-Lewis fracture) —> rigid septum render immobility of radial nerve —> easily injured during by fractured bony segments —> cannot do closed reduction)
3. **Radial tunnel

Question 38

P/E of Radial nerve

Answer 38

1. Wrist + Finger drop
2. ***EDC
   - Extend MCP against examiner with IPJ flexed —> eliminate effects of lumbricals (IPJ extension)

Differentiate high vs low palsy:
Motor:
- Finger drop (EDC, EPL, EI, EDM) = Low (PIN palsy) —> ECRL still present: wrist extension present but **weak with **radial deviation (weak ECU)
- Finger + Wrist drop (BR, ECRL) = High (Proximal to forearm)
- Triceps involved = Very high (Arm / Axilla)

Sensory:
- More proximal —> More sensory area deficit

DDx of PIN palsy Finger drop (SpC Revision):
1. Extensor tendon rupture
2. Extensor dislocation
3. MCPJ dislocation

Question 39

Decompression vs Reconstruction

Answer 39

Decompression:
- Early cases to prevent target organ atrophy (will be irreversible once atrophy developed)

Reconstruction of tendon / muscle function:
1. Severe chronic compression
2. Incomplete nerve regeneration
3. Target organ atrophy (Motor end plate / Sensory organ: irreversible even after decompression)

Tendon transfer:
- Donor tendon (dispensable tendon without functional impairment) —> Recipient tendon (e.g. Camitz opponensplasty for median nerve (Palmaris longus tendon (not much function in adult) to APB))

Nerve transfer / Neurotisation:
- Donor nerve (e.g. AIN supplying PQ, even if PQ function loss, still have PT for pronation) —> Recipient nerve (e.g. transfer Ulnar nerve to get axons growing distally —> try to recover intrinsic muscles motor function)

Question 40

Foot drop

Answer 40

Deep peroneal nerve:
- Motor:
—> Tibialis anterior (Ankle dorsiflexion)
—> EHL, EDL (Toe extension)
- Sensory: Dorsal 1st web

Common peroneal nerve:
- Motor: Deep peroneal nerve + Superficial peroneal nerve (Peroneal longus + brevis, Lateral calf) (Ankle eversion)
- Sensory: Deep peroneal nerve + Superficial peroneal nerve (Foot dorsum sensory)

Sciatic nerve:
- Motor:
—> Common peroneal nerve + Tibial nerve (Gastrocsoleus (Ankle plantar flexion), FHL, FDL (Toe flexor), Tibialis posterior)
—> Sciatic nerve itself: Hamstring
- Sensory: Common peroneal nerve + Tibial nerve (Sole sensory)

L5 nerve root:
- **Intact peroneal longus + brevis (Intact ankle eversion)
- **Weak hip abductor (Gluteus medius)