The trio were part of a ‘marauding mob’ who roamed the streets of Kingsway and Newton on November 11, breaking down fences.
When Robyn Pelling, 19, confronted them for damage to her rented Kingsway house, they knocked her unconscious with wooden posts.
Jessica Barnett, 18, of Morton Road, Blacon was this week put behind bars for 12 months for violent disorder.
She admitted standing holding a stick as another youth beat Robyn and encouraging them to attack Adam.
A 16-year-old boy from Kingsway and a 17-year-old boy from Blacon, who cannot be named, will spend six months in custody for violent disorder. The boys admitted trying to hit Robyn with a fence-post and attacking her housemate Adam Dinsmore.
All three youths have criminal records and Barnett has a previous conviction for assault.
There was not enough evidence to prove who struck Robyn.
The detective who investigated the attack by around 20 youths says it is ‘shameful’ the other offenders have not faced up to their crimes.
DC Andy Kevan said: ‘I am pleased these three youths have been brought to justice, but it is an indictment on society that others have not owned up to their role.
‘The fence posts had six-inch nails sticking out of them and this could easily have been a murder inquiry.
‘A lot of teenagers out there know what part they played, and their parents know what they did, yet they haven’t made them come forward to face up to it.’
Ten months later Robyn has a permanent blind spot in her eye caused by a detached retina, and suffers from migraines.
Her housemate Adam Dinsmore was left with severe cuts and bruises after two teenagers assaulted him with posts.
Dozens of Kingsway and Newton residents came forward to identify the youths after seeing photographs of Robyn’s injuries in The Chronicle.