A deaf teenage girl was kicked in the head and had her hearing aid smashed by a gang of youths who were trying to steal her mobile phone.
Cleveland Police described the robbery, in which the 19-year-old's male friend was also attacked, as "nasty".
The girl suffered a suspected broken jaw and her prosthetic ear also damaged when she was kicked in the head.
The incident happed in Wilton Street, Middlesbrough, on 6 July. Police have just released details of the attack.
Cash taken
Detectives believe the gang was made up of three males and two girls.
A Cleveland Police spokesman said the teenager's companion was "rugby tackled" to the ground and his mobile phone and wallet containing cash and credit cards were taken.
Both were treated in hospital for minor injuries.
News of the attack comes as the latest crime figures suggested a rise in young people carrying mobile phones was behind a big jump in street crime.