Tests have failed to determine the source of a back problem which has sidelined jockey Michael Walker indefinitely.
Jockey Michael Walker will be sidelined indefinitely with a mystery back problem which threatens his career.
Walker, who has had a hip replacement, said initial tests indicated that was fine but he was forced to call for help when his back seized up during a race at Moonee Valley on Friday night.
He told Melbourne's RSN927 on Tuesday he would have further tests to try to get to the bottom of the problem and he wanted to return to riding.