As eluded to last week Posterior Interosseous Nerve (PIN) Compression Syndrome, a deep branch of the radial nerve, is felt to be radial tunnel syndrome with paralysis.
Symptoms depend on whether the PIN is compressed before or after it divides into medial and lateral branches.
Before: Results in complete paralysis of the digital extensors, and extensor Capri ulnaris. Wrist will become dorsoradial deviated.
After-Medial Branch: Paralysis of extensor carpi ulnaris, extensor digiti quinti, and extensor digitorum communis
After-Lateral Branch: Paralysis of abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, and extensor indicis proprius
Common causes:
Synovitis and Joint Ganglions
Nerve compression following fracture repair
Idiopathic Compression can occur at these sites
Fibrous bands anterior to the radial head
Tendinous origin of Extensor Carpri Radialis Brevis
Arcade of Froshe –Most common, it is the tendinous proximal border of supinator
Distal Edge of Supinator –Least Common
Exam:
Increased pain with resisted supination of the forearm
Supination with Wrist Flexion symptoms will likely be reproduced.
Pain with resisted extension of the middle finger
Unable to extend thumbs or fingers at MCP joints, but can extend at PIP and DIP joints
