Issues
1. Loss of wrist extension
2. Loss of finger extension
3. Loss of thumb extension
Aetiology
High lesion (loss of wrist extension)
- humeral fracture (Holstein Lewis)
- compression (Saturday night palsy)
Low lesion (PIN - wrist extension intact)
- fracture / dislocation elbow
- trauma / laceration
- iatrogenic - ORIF proximal radius
Clinical Features
High lesion
- triceps weakness uncommon (lesion usually past triceps innervation)
- wrist drop (ECRL, ECRB)
- inability to extend MCPJ (EDC)
- inability to extend thumb (EPL, EPB)
- sensory defect in anatomical snuffbox
Low lesion
- triceps intact
- wrist extension ECRB / ECRL intact
- no sensory deficit
- inability to extend MCPJ (EDC)
- inability to extend thumb (EPL, EPB)
Splints
1. Radial Splint / Lively splint
- rubber bands & outrigger
- bands replace EPL / ECRB / EDC
2. Simple static extension splint
- passive ROM to maintain supple joints
Investigation
NCS at 3/52
- SNAP intact - neuropraxia
EMG at 3/12
- no reinnervation potentials
- poor prognosis
Options
1. Explore at 4/12 if no recovery
Terzis et al Plast Recon Surg 2011
- surgical repair in 35 radial nerves
- 77% good outcome
Lee J Hand Surg Am 2008
- sural nerve grafting of high radial nerve injury
- 80% good or excellent results in regards motor function
2. Tendon transfers
Indications
- no recovery at 6 - 9/12
- usually 1 mm / day
- should see ECRL by 6 months
Tendon Transfers
Goals
1. Wrist Extension / ECRB
Pronator Teres
2. Digit Extension / EDC
A. FCU
Problem
- is the most important wrist flexor
- only ulnar deviator / may result in radial deviation
B. FDS middle finger
C. FCR
- many authors favour
- gives strong grasp
3. Thumb Extension / Abduction
A. PL to EPL
- line of pull via 1st dorsal compartment
- works well as gives some abduction
B. FDS to RF (if no PL)
- can pass through intra-osseous membrane or tunnel subcutaneously
High Radial Nerve Transfers
Basis is use of PT for wrist extension
Jones Transfer
1. PT to ECRL / ECRB
2. FCU to EDC
3. FCR to EPL (+ EPB & APL)
Problem is that both wrist flexors are transferred
- loss of FCU may lead to radial deviation
Brand Transfer
1. PT to ECRB
2. FCR to EDC
3. PL to rerouted EPL
Problem
- PL absent in 20%
- alternative FDS RF / MF
- take through interosseous membrane or tunnel subcutaneously
Boyes
1. PT to ECRL / ECRB
2. FCR to EPB & APL
3. FDS MF / EDC
4. FDS RF / EPL & EIP
Technique Brand Transfer
Set up
- tourniquet
- arm table
Incisions
1. PT incision
- over insertion on midportion radius
- dissect between ECRL and ECRB
- take entire periosteal insertion off radius
- need to keep long
2. FCR / PL incision
- distal volar incision
- take both tendons as distal as possible
FDS RF
- make incision in palm over A1 pulley of RF
- if need FDS to RF must take proximal to bifurcation
3. Dorsal incision
- proximal to extensor retinaculum, expose EDC and EPL
Transfers / Tensioning
1. PL to EPL
- tunnel PL / FDS subcutaneously under SRN to EPL
- place thumb abducted and extended
- pulve taft weave
- through tendon 4 times at 90 degrees to each other
- 4.0 ticron stitches at each pass
- check tension
2. FCR to EDC
- pass FCR through all 4 tendons of EDC
- may need to take through EDMB
- check tension
- fingers should be in cascade in wrist flexion
- full extension with wrist extension
3. PT to ECRB
- PT passed through ECRB with wrist in full extension
- again check tension
Post op
0 - 4 weeks splint
- wrist and MCPJ extension
- active finger extension (DIPJ, PIPJ)
4 - 6 weeks
- active MCPJ extension
Wrist flexor to finger extensor
- teach patient to flex wrist & extend fingers
- after a while they can extend fingers without flexing fingers
Pin Palsy Transfers
Wrist extension not required
Transfers
- FCR to EDC
- PL to EPL