By Jane Elliott
Health reporter, BBC News
John feels fitter and healthier
John Glover is an active man who enjoys walking and looks forward to playing golf.
But until recently it was a very different story - he was able to walk only a few yards and needed a buggy to transport him any further.
Each day the 70-year-old was in constant pain - but after four joint operations he is a new man.
John has had both hips replaced, one ankle replaced and one ankle fused, where the joint is fixed into a rigid position.
Focus on ankle
"There is no pain now," he said.
"It was nearly impossible to walk before. The pain was just horrendous."
It is John's ankle replacement that is causing the most interest.
Each year there are more than 65,000 knee replacements and a similar number of people have a hip replaced.
But only 1,000 a year get a new ankle joint and the technique is still regarded as developmental, rather than a mainstream procedure.
And John is one of only a handful of patients in the UK who have had both the replacement and fusion.
Traditionally surgeons have been unwilling to carry out a replacement because of the high failure rate of at least 1-2% a year.
But Paul Cooke, an orthopaedic surgeon from the Nuffield Orthopaedic Centre in Oxford, explained that new designs and techniques were making the operation John had much less controversial.
"Over the next few years they will be doing a lot more," he said.
"Just recently it has spread from being performed in a few centres to becoming more widely available."
But he said that despite the growth in popularity, surgeons would still have to select their patients carefully.
"At one end of the spectrum, if you had an 18-year-old boy whose other joints are healthy, but who has broken his ankle and gone on to get arthritis, you would always fuse him because he needs a robust structure. He will compensate by all his other joints.
Paul Cooke is studying ankle replacements and fusions
"The perfect replacement patient would be a 70-year-old with diffuse arthritis who has stiff joints elsewhere and more limited expectation of movement."
A small study at his centre of 35 replacements and 35 fusions showed that ankle replacements are not always as stable.
All those who had a fusion were able to return to golf after surgery, compared with two-thirds who had a replacement. The remaining third could still play, but needed an ankle brace for support.
"There are pros and cons of both ankle fusion and replacement depending on the particular patient and their different requirements, but both types of surgery offer real options for people with osteoarthritis in the ankle to keep them active and mobile," said Jane Tadman, of the Arthritis Research Campaign, which is supporting Paul Cooke's research into ankle fusion versus replacement.
John, who blames years of rugby for the wear and tear on his joints, is in a perfect position to comment on fusion and replacement and has no doubt which method he prefers.
"I think last year's ankle replacement is the best," he said. "Because that has given me complete movement. The other one has very restricted movement and is locked in a certain position.
"For me ankle surgery was the only answer - and I'm really glad I had it done.
"Walking has got easier and I can get on with my life."