Star hurdler Liu Xiang is expected to be back on track in six months after last week's surgery on his foot was declared a "success".

"We felt he did very well through the surgery," said Thomas Clanton, the doctor who performed the procedure at Memorial Hermann-Texas Medical Center in Houston on Saturday. "It was exactly what we had anticipated finding. His prognosis for running in the future is quite good."

Liu, 25, left the hospital yesterday morning Beijing time in a wheelchair, looking relaxed and making faces at people outside the hospital. He joked that his only feeling during the operation was being "hungry".

He needs six months for rehabilitation and the process "is as important as the surgery", Liu's coach Sun Haiping said.

"The surgery is the first step and he still needs a careful recovery plan," he said.

Liu will go back to the hospital for further consultation on Wednesday and a rehabilitation plan will be worked out after that.

"Liu has been a professional sportsman for a long time, so his physical condition is very good, which will make his rehabilitation faster than for normal people," Sun said.

"Liu will have a good rest and then walk with crutches. After the Spring Festival (January 26), he may go jogging."

Liu will stay in Houston during his rehabilitation. "The doctor said the rehabilitation needs some six months and we are not trying to rush him back to training," Sun said.

A severe injury on Liu's right Achilles' tendon forced the 110m hurdles world champion to pull out of the first round of the competition at the Beijing Olympic Games in August - leaving him in excruciating pain and the whole nation heart-broken.

During the nearly three-hour-long surgery on Friday in Houston, Liu had four small pieces of bone, about the size of peas, removed from the Achilles' tendon in his right foot, including a bone spur between the Achilles' tendon and ankle bone.

Clanton said the injury happened over a period of time, resulting in microscopic tearing of the tendon's fibers, which cause bleeding. This process produced calcium and resulted in the bone pieces forming within the tendon itself.

Questions:

1. In which American city did Liu Xiang have surgery?

2. How long will Liu’s rehabilitation take?

3. What injury did Liu have?

Answers:

1. Houston.

2. At least six months.

3. He had a severe injury on his right Achilles’ tendon.