50 years of hip surgery
Exactly 50 years ago, a British surgeon called John Charnley developed a technique that revolutionised hip replacement operations.
Later he was knighted for his efforts - and the work of the man now known as Sir John Charnley has since become the standard procedure.
It is an operation that has been carried out on patients across the world.
And it all started half a century ago in a small hospital in Lancashire.
One of the latest patients to benefit from Sir John's work is former teacher Harry Hagan.
For the past five years or so, Mr Hagan has had a troublesome hip.
It has stopped the former teacher from indulging his love of tennis and walking.
Now Harry's undergoing a total hip replacement at Wrightington Hospital near Wigan in Lancashire - exactly the place the first successful hip operation was performed by Sir John Charnley, 50 years ago to the day.
Wear and tear
Harry said he wanted to be able to be active again.
"I want to be able to run a little, take long walks in the countryside, play a bit of social tennis, get back to the gym.
"I want to take up what I would consider to be a normal lifestyle for someone who is - other than the hip - fit and well."
Surgeons have been carrying out hip surgery since the 19th century.
Sometimes they used ivory to rebuild bone that had decayed through conditions such as arthritis, or simply wear and tear.
Techniques and results varied greatly, with some doctors prescribing pain killers or bed rest, while others totally immobilised the hip altogether.
But Sir John Charnley, who died in 1982, was a surgeon who also loved engineering.
As his wife, Lady Jill Charnley, remembers his interest was first aroused when he saw a patient suffering from an unusual problem with an existing hip implant
"This patient came to John because the squeak upset his wife so much.
"When they were having a meal together and he leaned forward to get the salt, it squeaked and it made her feel sick!
"That started Charnley on thinking about what was going on in the joint, and then of course he had this engineering bent and really re-designed nature."
His great innovation was to realise that low friction between the ball and socket of the hip implant was vital.
So he designed his own implant as well as the surgical procedure to go with it - to create the total hip replacement.
And perhaps just as important, he came up with a method of teaching the technique that has been used to spread to word to doctors across the world.
Many have travelled to Lancashire to study the technique.
The Charnley technique is seen as revolutionary.
"As an orthopaedic surgeon I'm bound to be biased" says Anil Gambhir, a consultant at Wrightington.
"I'm bound to tell you hip replacements are the number one innovation. But I don't think I'm far wrong.
"It certainly ranks along side the discovery of penicillin, coronary artery bypass grafting, coronary stenting.
"But above all, it's had a huge impact on patients' lives around the world, delivering pain relief and a return to function."
For some surgeons, Wrightington hospital is almost a place of pilgrimage.
The former TB hospital is now an orthopaedic centre of excellence for the NHS.
But most patients walking around today, thanks to a replacement hip, have no idea of the debt they owe to Sir John Charnley.