Transplant doctors are having to split livers from deceased donors as there are too few donations.
"We're good at it, but it's not something to be proud of," said Professor Chan See-ching, chief liver-transplant surgeon at the University of Hong Kong.
He said about half of the patients on the waiting list for a transplant die before getting one.
"We wanted to stretch the limits a bit more, to help more people."
Local surgeons have mastered the skill of using partial livers, having performed many transplants from live donors.
Chan said many family members offered to be live donors but were not accepted because of their own health conditions or mismatching blood types.
"We can't put them at risk, even when the patient is in critical condition," he said.
Chan told of a case about 10 years ago when a father in his 70s desperately wanted to give part of his liver to save his son.
When doctors told him he was too old and his body was not up to it, he said he would kill himself so his son could have his liver. He was talked out of it and his son died before he got a donation.
Forty-five livers were donated last year, the best year in the past decade. There were a further 33 live donors, but there were still 121 people in need at the end of the year. Five of the livers from dead people were split in half, benefiting 10 people.
There were generally three such procedures in the few years before that.
A healthy large liver, such as from a man weighing about 70kg, can be split in two.
The right side, about two-thirds of the liver, is a suitable transplant for an average adult. The remaining left side can be used for a child or small adult.
The results were just as good as whole-liver transplants, Chan said, although the procedure required more exacting surgery, involving connections to smaller blood vessels.
A whole liver can be transplanted within 10 hours of being removed from the donor's body, whereas split livers have to be used within three to four hours.
As of September 13, there were 135,311 people listed on Hong Kong's Centralised Organ Donation Register.