Three weeks after accidentally cutting his thumb off with a circular saw while woodworking in his Kaleen home, Mr Arezi is confident of regaining full function in the digit.

''I didn't feel anything. I started screaming because I couldn't find my thumb and I called my wife to come and find my thumb,'' Mr Arezi said.

Mr Arezi's wife picked up the thumb and a neighbour drove the couple to Calvary Hospital, arriving at the emergency department less than 10 minutes after the accident occurred.

''By the time I got into the car I said, 'Clear your mind you're not going to have the finger any more','' Mr Arezi said.

From the moment of the accidental amputation, a six-hour countdown began to the cells dying, making surgery a waste of time.

Mr Arezi was transferred to the Plastic, Reconstructive and Hand Unit at the Canberra Hospital where surgeons Ellis Choy and Muhammad Ali Hussain, assisted by Hardeep Jhattu, then managed to reattach the thumb.

Dr Hussain said that the procedure had involved some extremely delicate surgery with no guarantee it was going to work.

''You have to do the bone first and then you have to do the tendons and then the vessels. If you start doing the vessels, not the bones, then any movement can rupture everything,'' Dr Hussain said.

A careful watch was kept on it for two days for complications such as a blood clot which could have led to the thumb's death.

Dr Hussain said the first instinct of people who suffered such an injury, and those around them, was to stem bleeding. But some people failed to retrieve and protect the severed body part for possible re-attachment.

A severed finger should be wrapped in cloth and then placed in ice. Wrapping the finger in cloth protected it from frostbite which could also kill cells.

Dr Hussain said Mr Arezi had been lucky that he suffered a clean cut, was close to a major hospital and that the necessary theatre, equipment and staff were available soon after the accident occurred.

''You have to have microsurgery facilities available, you need to have instruments available, you need to have a microscope available,'' Dr Hussain said.

''He [Mr Arezi] was quite fortunate that on the day he came we had the theatre available straight away.''

The loss of a thumb would cost a patient at least 70 per cent of their hand function and psychological factors usually resulted in the loss of the use of all other fingers on the hand. In some cases where a thumb could not be saved, plastic surgeons would surgically remove one the of the patient's big toes and graft it on to the hand to act as a replacement.

Mr Arezi said he was extremely grateful to the hospital staff.

''[Cutting the thumb off] is the easy job - it took me one second to do it,'' he joked.

It has been wired up to prevent movement, and when it heals, Mr Arezi will have physiotherapy to restore function.

And Mr Arezi is determined to resume his woodworking.