Hand Injuries

Median nerve: C5 – T1AbPB, OP, FPB (all in thenar eminence); lateral 2 lumbricals; FDS Motor: flex DIPJ of thumb; touch tip of thumb to LF against resistance; flex thumb and palpate thenar emimence; wrist flexion; A-OK sign; abduct thumb against resistance (recurrent branch)Sensation: volar thumb and radial 2 ½ fingers

Radial nerve: C5 – T1Motor: extend wrist and fingers (post interosseous nerve); extension of thumbSensation: dorsum radial aspect of hand, thumb and radial 2 ½ fingers

Ulnar nerve: C7 – T1ODM, FDM, AbDM (all in hypothenar eminence); AdPB; interosseous muscles; ulnar 2 lumbricals; deep head of FPLMotor: spread fingers and push together against resistance; thumb adduction Sensation: sensation dorsal and volar ulnar 1 ½ fingers

Capitate and hamate appear in infancyTriquetrum appear 3-4yrsLunate appears 4-5yrsTrapezium, trapezoid appears 5-9yrsScaphoid appears 6-10yrsPisiform appears 10-12yrsProximal row is unstable, others are stableChildren more likely to injure radial epiphysis than carpal bones

Normal 2pt discrimination in fingertips is <6mm

Epidemiology: most commonly fractured carpal bone (70%); 85% 15-29yrs; 50-60% mid-scaphoid, 15-35% proximal, 10% distal; due to fall on dorsiflexed hand or axial load on thumb; another associated injury in 12%Pathophysiology: blood from radial artery entering from dorsal side at waist to supply proximal pole; vascularity of proximal pole depends on intraosseous blood flow; ASB = bony radial styloid, EPB, EPL; the more proximal / oblique / displaced the #, the greater the risk; unstable if oblique / >1mm displaced / rotation / comminution

Scaphoid Fracture

Triquetrum Fracture

Lunate / perilunate Dislocation

Examination: ASB tenderness (93% sensitivity, 16% specificity)XR: takes 1-2/12 for XR to show avascular necrosis; XR 70% sensitivity with high false +ive rateCT: 89-97% sensitivity, 91-100% specificity; if suspect but XR normal (risk of # 1-5%), suggest doing early CT to avoid unnecessary immobilisationMRI: nearly 100% sensitivity and good for avascular necrosis, ligament injury, carpal instabilityBone scan: 92-100% sensitivity, 87-98% specificity, can’t be done until 72hrs and has high false +ive rateManagement: scaphoid cast 6/52; ORIF if >1mm displacement, >15 ° angulation Complications: 0.1-1% long term complication rate; 30% proximal pole #’s get avascular necrosis (incidence increases the more proximal the #; shows up on XR as density of bone); 50% avascular necrosis if >1mm displacement; nonunion with waist #’s (50% nonunion if >1mm displacement); complex regional pain syndrome

Lunate dislocation: reduce by compression over lunate, wrist extended and flexed; may need OT

Peri-lunate dislocation: dislocation of capitate dorsally; lunate still attached to radius; reduced by traction

Trans-scaphoid perilunate dislocation: distal scaphoid fragment displaced posteriorly with rest of carpal bones; maybe # of radius and ulna; reduce via traction; may need OT

Usually due to forced dorsiflexion; can cause degenerative arthritits, avascular necrosis, median nerve compression

Scaphoid dislocation: proximal pole goes dorsal, distal goes volar

2nd most common carpal fractureAvulsion or fracture through bodyTender over dorsum of wrist distal to ulnar styloid

Lunate Fracture

UncommonRisk of avascular necrosis - blood supply enters distallyUsually occurs with fractures of other carpal bonesDue to FOOSH

Hamate Fracture

2% of carpal fracturesDue to racket sportsMost fractures involve hook of hamateRisk of ulnar nerve injury

Bennett’s Fracture

Intra-articular fracture-dislocation of carpo-metacarpal joint of thumbSmall medial fragment maintains contact with trapezium; distal fragment displaced proximally, radially and dorsally by pull of APL

From axial blow to partially flexed thumb

Management: traction, abduction and pressure over base of thumb; usually needs K wire fixation

Rolando’s Fracture

3 part fracture of base of thumbIntra-articular

UncommonWorse prognosis than Bennett’sAlways needs ORIF

Boxer’s Fracture

Fracture of neck of 5th metacarpal

Can accept almost any degree of angulation (up to 45° is OK)Rotation important to detect and requires reductionEarly mobilisation

Fracture of Other

Metacarpals

Give neck fracture a pull if: >10° angulation in AP / lateral (>20° if 1st / 4th MC) >50% displacement then buddy strap or splintUnstable if: rotated spiral / oblique, multifragment, >50% displacedOT if: intra-articular, open, multiple fracturesFracture of metacarpal shaft: rotational deformity and shortening more likelyFracture of metacarpal base: often complex, communitued, associated with carpal bone fracture; 4th and 5th associated with ulnar nerve injury; often need OT

MCP Dislocations

Hyperextension dorsal dislocation; volar plate may be trapped in joint (complex)Management: relocate by flexing wrist pushing phalanx distal and volarly onto MCPJ (avoid pure traction and hyperextension as may make simple complex) splint in flexion; if complex may need OT; closed reduction hard if metacarpal head button-holes through capsule

PIP/DIPJ Dislocations

Usually dorsal; may be irreducible if entrapment of avulsion #, profundus tendon or volar plate; radial collateral ligament 6x more likely than ulnar collateral ligament to ruptureManagement: reduce by traction and mild hyperextension buddy strap or splint in flexionIf of thumb, usually open

Phalanx Fracture

Middle phalanx fractures are unstable and require OTK wire if fragment >5mm or involves >1/4 joint surfaceIf undisplaced shaft fracture = splint 2/52If DP fracture = symptomatic onlyPP has no tendor attachments so fractures often cause volar angulation

Tendon Injuries

Flexor Tendons:

I Insertion of FDS to FDP tendon; lose DIPJ flexion FDP = flexes DIPJ; if broken, can still flex PIPJ II Both FDS and FDP involved FDS = flexes PIPJIII Distal edge of carpal tunnel to proximal edge of flexor sheath; good outcomeIV Carpal tunnelV Proximal to carpal tunnel; injuries tend to be severe

Tendon sheath function important – making more prone to deep space infections

<25% division can be treated conservatively

Extensor Tendons:

I DP and DIPJMallet finger: damage to distal extensor tendon to distal phalanx via forced flexion (at attachment to bone = type I, with avulsion # = type II, with >20% articular surface avulsed = type III) Treat conservatively: if only chip fracture and <15° movementt lost Otherwise 6/52 splinting, or K wire if >2mm / >1/4 joint surface fragment Swan neck deformity if not appropriately treatedII Over MPIII Over PIPJCentral slip rupture: due to dislocation of PIPJ (maybe delayed); tender over middle of PIPJ, full extension of finger may be possible; if complete laceration, can cause volar displacement of lateral bands causing them to become flexors boutonniere deformityIV Over PPV Over MCPJ; consider human bite

Tendon Injuries

VI Dorsum of hand; may be proximal to junctura tendinae so extension of MCPJ may be possible Usually need OTVII Over wrist; extensor retinaculum; needs OTVIII Over distal forearm; OT if >25% injury followed by splint

Tendon sheath function less important (less communication between extensor sheathes); central slip attaches to MP, 2 lateral bands to DP; a complete tendon lac prox to junctura may still have normal extensor function

<80% division can be treated conservatively (splint 6/52 if mid-extensor, 8/52 if distal)

Infections: most staph aureus; 30% G-ive if diabetes; tender over tendon sheath distant from area of penetration; treat with flucloxacillin

Nerve Injuries Nerves superficial to digital arteriesSurgery needed if: thumb, ulnar border of little finger, distal index finger, dominant hand

Amputation

Better prognosis if proximal to PIPJ (terminalisation if through DIPJ); otherwise best to reimplant within 6hrs); Bone, tendon, skin lasts 8-12hrs warm ischaemia, 24hrs cold ischaemia; Muscle lasts 6hrs warm ischaemia, 12hrs cold ischaemia

Management: wrap in saline soaked gauze place in water tight bag put in very cold water >1cm finger tip amputations need grafting Reimplantation contraindicated if: other severe injury, significant chronic illness, severely damaged, >50yrs, avulsion injury, cooling delayed >6hrs

Nail Injury50% nail bed injuries have associated fracture of DPManagement: place drainage hole in nail before replacing; suture nail in place for 3/52 If subungal haematoma – trephination OK if DP fracture, but need to give prophylactic antibiotics; remove nail if trephination doesn’t relieve symptoms