A Gold Coast doctor who allegedly hog-tied and then sat on a young boy during a consultation has gone on trial.

Police charged Dr Neville Davis with common assault after the alleged incident was photographed by the seven-year-old's mother.

Magistrate Paul Johnstone was told the boy suffered from Attention Deficit Hyperactivity Disorder (ADHD) and was seeing Davis for behavioural problems when the alleged assault happened at Southport in October 2012.

The paediatrician has pleaded not guilty to common assault and is facing a summary trial in the Southport Magistrates Court.

A second charge of deprivation of liberty was discontinued by the police prosecutor before the hearing began.

The court heard evidence from experienced paediatrician Dr Kerry Sullivan who once operated his own private practice beside Dr Davis's consultation room.

Dr Neville Davis has pleaded not guilty to common assault. ( AAP: Dave Hunt )

He told the court the idea of tying a child up did not seem appropriate and it was a practice he would never personally undertake.

Police prosecutor Douglas Bettany asked Dr Sullivan: "Can you think of any circumstances where it would be appropriate to sit on a child?"

Dr Sullivan replied: "No."

Defence barrister Kerri Mellifont QC told the court the boy was disruptive at home and at school, and his mother was concerned her son was often carrying dangerous items including knives.

Under cross-examination by Ms Mellifont, Dr Sullivan agreed that a mother squatting over a her own child was an appropriate restraint technique, which can be used to help calm a child.

"It is appropriate because you are not hurting the child," he said.

The seven-year-old boy, whose name has been suppressed, is due to give evidence in a closed court.

The trial continues.