A fall in which Kathy O'Hara suffered a serious injury has been determined an accident with no other rider to blame.

O'Hara, who expects to be back riding in two weeks, came down in the ATC Australian Oaks at Randwick on April 9 when Single Gaze clipped heels with Happy Hannah ridden by Blake Shinn.

Damien Oliver, Blake Shinn and Glyn Schofield attended an adjourned inquiry before Racing NSW stewards in Sydney on Wednesday.

The stewards panel said Oliver on Jameka was improving between Schofield and Shinn into a run they found he was entitled to take.

Shinn's mount Happy Hannah in turn made contact with Single Gaze.

"The fall, serious as it was, was not the result of rider error," chief steward Ray Murrihy said.

"There was a discernible shift, but not great, from Damien Oliver.

"There was slight contact - small but significant.

"Kathy O'Hara was awkwardly placed but it was what we would call a racing incident."

O'Hara suffered sterno-clavicular damage which hampered her breathing and underwent surgery to relieve pressure.

Her recovery has been more rapid than predicted and she says she will be ready to ride in another two weeks, about four weeks ahead of schedule.

"I will be back at trackwork tomorrow," she said.

"It was painful and uncomfortable until they found the problem.

"I should be back riding in two weeks."

Single Gaze, who O'Hara rode to win the Group One Vinery Stakes, suffered only a minor graze to a leg in the incident.