Death rates following hip replacement surgery fell by half in England and Wales between 2003 and 2011, a study in The Lancet has found.
Although death within 90 days of surgery is rare, mortality decreased from 0.56% to 0.29% in an analysis of more than 400,000 patients.
The researchers said that fitter patients and better physiotherapy could be behind the decrease.
They added that simple treatment options would reduce the risk further.
Researchers from the universities of Bristol, Oxford, East Anglia and Exeter used data from the UK's joint-replacement database, the National Joint Registry, to look at death rates following this type of surgery.
In their study they found that 1,743 patients died within 90 days of surgery during the eight years.
In 2004, 24,723 patients had hip replacement surgery and 139 of those died within 90 days.
While in 2011, there were 60,727 hip replacement operations carried out and 164 patient deaths.
The reason for the fall in death rates could be down to a number of factors.
The researchers identified the use of a spinal anaesthetic as likely to lead to fewer complications. Specific treatments to stop blood clots after surgery were also linked to a lower risk of death.
But people are also living longer and patients are recovering more quickly after surgery as a result of better post-operative care. For example, patients are encouraged to get up and start walking around the day after surgery.
The study said: "More recent generations of old people... are generally fitter and less frail than old people at the start of the study.
"Likewise, other aspects of surgery and anaesthesia have improved sufficiently to account for the change in mortality rates."
The research team noticed that people with certain medical conditions were at a much higher risk of dying following surgery - particularly those with severe liver disease, those who had had a heart attack and those with diabetes and renal disease.
Those patients who died were most likely to be elderly men, they said.
But there were also some unexpected findings. Overweight people (with a body mass index of 25-30) appeared to have a lower risk of death after hip surgery than those patients with a "normal" BMI of 20-25.
Ashley Blom, professor of orthopaedic surgery at the University of Bristol, said: "The finding that overweight people have a lower risk of death is surprising, but has been confirmed by other recent studies, and challenges some of our preconceptions.
"We need to concentrate efforts on reducing the risk of death in high risk groups such as those with severe liver disease."
But he said that the "dramatic" overall fall in death rates was "extremely good news".
"It is also very exciting that we can further reduce the risk of post-operative death by adopting relatively simple measures," Prof Blom said.
A spokesperson from Arthritis Research UK, welcomed the findings.
"This is great news for people in the UK who have osteoarthritis and require hip replacement surgery.
"Although not everyone who has arthritis will need hip replacement surgery, for many people, it's their only hope to reduce the pain, disability and stiffness associated with the disease.
"There are however always risks associated in having major surgery such as hip replacement surgery, so we advise people to discuss these risks with their surgeon before they decide to have a hip replacement."