Prime Minister Atal Bihari Vajpayee was reported to be "feeling good and comfortable" after a knee-joint replacement surgery at the Breach Candy Hospital in south Mumbai yesterday morning.

"He will be able to get out of bed on Friday or so depending on how much pain he is going through though we have already started exercises of the ankles right away to activate the calf muscles," Dr Chittaranjan Ranawat, the U.S.-based orthopaedic surgeon who performed the surgery, said yesterday, within hours of the surgery.

The operation of his arthritic right knee is a similar procedure as last time in October when the left knee-joint surgery was performed by Ranawat himself at the same hospital. Since then, his patient has been relieved of pain in his left leg but during the last four or five months the pain in his right knee was "quite significant", and hence the operation.

Physiotherapy could begin tomorrow depending on his response to pain, he said, with the prime minister expected to spend around eight to ten days in the hospital till he has recovered.

Though the prime minister will be able to walk normally after some time, one of the limitations of this operation is that it would be unadvisable for him to squat Indian style, said the surgeon. "A knee joint implant functions well for 15 years in 90 per cent of the cases though 10 per cent of the patients may need additional surgical intervention," he said.

Asked how arthritis could be prevented, he said: "Our understanding of the disease is not profound and therefore do not have a good method to arrest or reverse it. What can be done is relieve the pain, slow down progression and make the individual's life more comfortable by exercise, medication and reducing body weight."

Arthritic pain is greater in heavier patients due to pressure on the joints, he said. Asked whether he had asked the prime minister to reduce his weight, he said: "Logically, everyone should reduce weight."

The orthopaedic surgeon is expected to operate on 15-20 people this time in the city.

Vajpayee remained awake during the operation and was given an epidural anaesthesia that numbs the patient waist down. To a query on whether he talked with the prime minister during the operation, Ranawat, who was far more relaxed and cheerful this time round, replied, "a surgeon has to operate and not talk to his patient but the prime minister did talk to the anaesthetist."

When he was asked whether he had heard them talking about the forthcoming cabinet reshuffle, he chuckled and said: "You can get it from the horse's mouth." No visitors have been allowed for the next two to three days though Vajpayee has already started receiving get-well messages.

Congress party president Sonia Gandhi was one of the first to send a fax message wishing him speedy recovery, said Ashok Tandon from the Prime Minister's Office (PMO).

President K.R. Narayanan sent a bouquet of flowers through Governor Dr P.C. Alexander.

Bangladesh leader Sheikh Hasina has also sent a get-well message and Pakistan's military leader General Pervez Musharraf is said to have wished Vajpayee a couple of days back.

President Narayanan will most probably be the first dignitary talking to him and the first visitor will most probably be the governor.

The PMO's makeshift office, comprising of Brajesh Mishra, National Security Advisor, Tandon, Ashok Saikia, Sudheendra Kulkarni, Anand Rajan, two joint secretaries and supporting staff, will be operating from one of the rooms on the seventh floor of the hospital where the PM is staying. Vajpayee has also been accompanied by his foster daughter Namita Bhattacharjee, her husband Ranjan and their daughter.

After being admitted into the hospital in the afternoon on Wednesday, Vajpayee went through routine medical check-ups and later cleared files. After a light vegetarian meal, he watched Amitabh Bachchan's popular TV game show Kaun Banega Crorepati and went to bed early as advised. A keen movie buff, he watched Aamir Khan's new release Lagaan in New Delhi with his colleagues.