Definition
Symptoms & signs due to compression of AIN
Sites of Compression
Fibrous
- Pronator Teres (most common)
- FDS arch
- Fascial bands
- Bursa
Vascular
- thrombosis in leash vessels over AIN
Muscular
- aberrant belly FPL (Gantzer's)
- palmaris profundus
- aberrant FCR ulnar origin
- anomalous FDS origins
History
1. Pain in proximal forearm
- vague pain
- most common symptom
2. Motor deficiency
- FPL
- IF FDP
- PQ
3. No sensory disturbance
Examination
Discomfort over site of compression
Inability to tip-to-tip pinch grip IF &Thumb
- weak pulp-to-pulp pinch possible
- Weak FPL / Index FDP / PQ
Provocation
- resisted pronation with elbow flexed 90o
Investigation
EMG FDP / FPL / PQ
DDx
Rupture FPL / FDP
Median N entrapment
C8 lesion
Management
Non operative Management
Avoid Aggravating Factors
RICE
NSAIDS
Operative Management
Technique
Release
- as per pronator syndrome
Results
Schantz et al J Hand Surg Br 1992
- 20 cases of AIN compression
- operated on 15 with 12 good results / 3 required tendon transfer
- non operative on 5 / 3 continued palsy at 4 years
- recommended operative release