RIDDLED with bacteria, it took 10 weeks of antibiotics to clear a young man's blood and lungs of infection.

However, his injuries were mainly internal, with very few external signs visible, the High Court heard on Monday.

The former prison inmate, who accuses three cellmates of assaulting him last year, was so badly injured that his ribs were broken in multiple places, causing a part of his rib cage to be separated.

Details of the 22-year-old's medical condition emerged as doctors who treated him took the stand on Monday, the 6th day of trial of the accused assailants.

The victim, who cannot be named, was admitted to a high dependency ward in Changi General Hospital on May 6 last year, after he became breathless in his cell. Dr Andrew Tan, who did a CT scan on him, told the court that the patient had a fractured sternum, or breastbone, and fractures to several ribs.

Sternum fractures are rare, said Dr Tan, and are associated with severe injuries, such as when a steering wheel hits the chest in a traffic accident.

Dr Tan said that the fractures resulted in a segment of the rib cage to separate. Asked by Deputy Public Prosecutor David Khoo if such trauma can be caused by repeated punches to the chest, Dr Tan replied: 'It will not be a light punch.'

He also had small tears in his liver, also possible with repeated punches.

On May 7, the man became comatose and was moved to the surgical intensive care unit, where he stayed till May 22.

Dr Lim Teik Whai, who saw him in the SICU, said that the patient was in a 'poor state and had to be hooked up to a machine to help him breathe'.

Read the full report in Tuesday's edition of The Straits Times.