Military operation: THRs took 75 minutes from first incision |
The early years of THR involved painstaking research and experimentation – one nurse recalls Charnley designing 17 different surgical wire tighteners before the tool was perfected – and a number of significant setbacks. Charnley’s memoirs record the ‘dreadful weeks’ when the original Teflon-based design was found to wear out and cause adverse reactions in surgical patients.
The significant design breakthrough came in 1961, when a new material, high density polyethelene, was used in place of Teflon in the artificial hip bearing. The story has the classic elements of British post-war science: ingenuity, improvisation, long hours and a low budget.
Charnley was assisted by a young engineer, Harry Craven, fresh from an apprenticeship at the Metal Box Company. He began his new career in the late 1950s, making hip prostheses from the attic of Charnley’s home. Panels at the RCS exhibition tell the story in his own words:
It must have been early ’61 when this salesman came from High Density Plastics in Todmorden. … I started testing the sample by making bearings and putting them in the rocker shaft of my estate car. Charnley came in to say that he was going to Zurich – “what’s that you’ve got on the test rig?” I said “It’s high density polyethylene”. “Throw the thing away. It’s no good,” he said. But I carried on with my tests. I left it running all day and at the end of the day it had worn about half a 1000th of an inch. So I was happy with this and I used to do a graph of everything I tested and put the graph paper up in the workshop. It was running a week and all I got was a straight line going all round the room. I carried on, and I think Charnley was away about a month, and it was still running and it was still a straight line round the room when he got back.
The discovery of the new material, high molecular weight polyethylene (HMWP), was a turning point in the THR programme. Charnley made many subsequent modifications to the prosthesis and to the instruments and theatre equipment used for THR, while continuing to improve the surgical procedure. Among his many innovations were the clean-air operating system, the body exhaust suit and the tray system for the stages of the operation. The procedure itself developed a military precision:
On Thursday morning operating started. The surgeons started to scrub at 8-45am. The first patient was on the table for knife-to-skin at 9. Routine hip surgery was scheduled to take between 60 and 75 minutes and the patients were usually back in the Recovery Room by 10 past 10, the second patient going into theatre at 10-30. Four patients were scheduled for every list every day. Lunch was not a consideration and operating usually finished at 3-30pm.
Wrightington would go on to become a world centre for THR research and treatment. Since the early 1960s, whilst thousands of alternative total hip prostheses have been developed and marketed, the Charnley hip remains one of the most successful designs.
The exhibition’s curator, Dr Francis Neary of the Centre for the History of Science, Technology and Medicine at Manchester University, said: “THR is now one of the most performed elective procedures in the world. Its development was associated with innovation in materials, instruments and operative procedures – many of which have since been adapted to treat other joints, and applied across a range of surgical specialties.
“We have used objects, video and the personal accounts of innovators to reconstruct the story of THR from a variety of perspectives. This will be a unique opportunity to see how an important surgical innovation was developed through meticulous scientific research with a low budget in the early days of the NHS.”
Hip Histories runs until 29 July 2006 at the Royal College of Surgeons, London
Images copyright: The John Charnley Trust
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