Victorian jockey Peter Mertens has a punctured lung, busted ribs, a broken collarbone and a fractured ankle.

But Victorian Jockeys' Association boss Des O'Keeffe says Mertens is one of the luckiest riders going around as he starts a long road to recovery from his injuries suffered in a race fall at Hamilton on Monday.

"When Peter sees a replay of the fall I think he will say that Monday was the luckiest day of his life at the races," O'Keeffe said.

"It was a horrendous fall and how he escaped injuries to his head, neck and spine, I don't know."

Mertens' mount Leconi fractured its leg and collapsed, sending him into the turf while the jockey following him, apprentice Jordan Childs, could do nothing to avoid the fallen horse and rider.

A Group One-winning jockey, Mertens will be out of riding indefinitely as he mends from his injuries.

Mertens has ridden three Group One winners including Sirmione for Bart Cummings in the 2007 Mackinnon Stakes.

Childs, who has been riding for 18 months, fractured both wrists and is expected to undergo surgery on Tuesday night.

O'Keefe said Mertens was a senior Victorian jockey and it would not be unusual for him to ride at five to six race meetings each week.

He said that for Childs, the son of former top jockey Greg Childs, the injuries had come at the wrong time because with the spring carnival finished, there were more opportunities for apprentices to get rides.

Both horses, Leconi and Wantara, were seriously injured and had to be euthanised.

Stewards and jockeys inspected the track near the home turn where the incident happened but were satisfied the area was safe and proceeded with the last race.