Ulna Nerve

Aetiology

 

Low Lesion (Below Elbow)

 

Injury usually at wrist

- laceration at wrist

- fenetrating forearm wound

 

Ulna nerve laceration wrist

 

High lesion / Above elbow

 

Injury usually at elbow

- elbow fracture / dislocation

- compression (GA) 

- tardy ulna palsy

 

Low Lesion

 

1.  Claw hand deformity

 

Characteristics

- hyperextension all MCPJ 

- flexion of IPJ of Ring & Little fingers

 

A.  Absent lumbricals - loss of MCPJ flexion / IPJ extension to RF & LF

 

2.  Unopposed MCPJ extension - EDC 

 

3.  IPJ flexed by long flexors - less marked in high lesion because ulnar FDP paralysed

 

2.  Loss of interossei 

 

Weak finger abduction / adduction

Positive Froment's sign

Hypothenar & Interossei wasting

 

Froment's

 

3.  Numbness of ulnar  1 & 1/2 fingers

 

May have numbness of ulnar dorsum of hand

- depends on level of lesion

- if forearm, take out dorsal branch ulna nerve

 

High Lesion


Above +

 

A.  RF / LF FDP loss

- ulna paradox with less clawing 

 

B.  FCU weak

- weak wrist flexion

 

Goals

 

1.  Restore pinch / thumb stability

- thumb adduction (interposition to BR/ECRB)

- index abduction (EPB to 1st Dorsal Interossei)

 

2.  Correct MCPJ clawing

 

Management Low Ulna Palsy

 

1.  Thumb adduction

 

No donor long enough

- FDP LF tendon to BR / ECRB

 

Technique

- need interposition graft  i.e. FDP to LF)

- graft fixed to base P1 / normal insertion

- tendon passed along a line form base of MC III /  line of pull of Adductor

- bring out through dorsum between III and IV MC's

- attach to donor tendon BR or ECRB

 

2.  Index Finger abduction

 

EPB to 1st dorsal interossei

 

3.  Clawing of MCPJ

 

Goal

 

Prevent hyperextension of MCPJ's

- Want to create FFD

 

Options

 

Static

- Zancolli Capsulodesis / volar plate advancement

 

Dynamic

- reconstruction lumbricals

- split MF FDS / ECLR into 4

 

Zancolli Capsulodesis 

 

Transverse palmar incision

- each A1 pulley opened

- flexor tendons retracted

 

Volar plate raised as distally based flap & advanced proximally

 

Finger flexed to 20°

- volar plate sutured to new position

- mild FFD MCPJ created

 

Management High Ulna Palsy

 

1. FDP to ring and little

 

Buddy to middle FDP

 

Problem

- FDP flexes IPJ's before MCPJ's

- this unopposed flexion of IPJ can push object out of palm

 

2. FCU

 

Split FCR to FCU