A 30-year-Old male underwent excision of the right radial head. Following surgery, the patient developed an inability to extend the fingers and thumb of the right hand. He did not have any sensory deficit. Which one of the following is the most likely cause?
Clinical features of radial nerve palsy 

Clinical features depend upon the site of the lesion.

1) 1f lesion is high

Wrist drop, thumb drop and finger drop.
Inability to extend elbow, wrist, thumb & fingers (MP joint)
The patient can extend interphalangeal joints due to the action of lubricants and interossei.
Sensory loss over posterior surface of arm & forearm and lower lateral half of forearm.

2) If the lesion is low
a) Type I


Wrist drop, thumb drop and finger drop.
Elbow extension is preserved.
Sensory loss over the dorsum of first web space.

b) Type II

Thumb drop and finger drop
Elbow and wrist extension is preserved
Sensory loss over the dorsum of first web space

Clinical features of posterior interosseous nerve

It is prone to be injured in injury & operations of radial head- neck.
There is no sensory deficit as it is a pure motor nerve.
Wrist extension is preserved (i.e. no wrist drop) due to spared extensor carpi radialis longus .
Presents with loss of extension of metacarpophalangeal (MP) joints i.e., thumb & finger drop.
Injury to Posterior interosseus nerve
latrogenic injury to common extensor origin
Injury to anterior interosseus nerve
High radial nerve palsy