BIRMINGHAM HIP™
Resurfacing System
Friction: deciding factor
| Thus by the 1970's three types of total hip replacement were in common use, the McKee, Charnley and Ring types. |
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Surgeons across the world experienced initial success with all varieties and attention then focussed on which would be more durable. Charnley's intervention at this stage proved decisive.
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| He returned to his favourite theme of frictional torque. He built a pendulum comparator to test the frictional torque of the McKee metal on metal joint versus the Charnley metal on polyethylene joint. |
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| Under test the McKee metal on metal came to a juddering halt and the Charnley joint kept on swinging. |
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| Thousands of visiting surgeons to Wrightington were immediately convinced of the superiority of the Charnley joint. |
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| The metal on metal joint finally ended in the late 1970's when McKee and Ring themselves switched to metal on polyethylene articulations for their own hip replacement designs. |
Charnley died believing that his metal polyethylene joint had been totally vindicated. McKee died believing that his metal on metal joint had been rightly superceded by the metal on polyethylene articulation. Peter Ring who is still alive was initially optimistic about his new polyethylene joint but with the passage of time saw the results ruined by osteolysis from polyethylene debris, a complication unheard of in his earlier metal on metal joint. Ring now deeply regrets ever moving away from the metal/metal articulation. Satisfactory results have been published for the McKee metal/metal, 4,5 the Charnley 6 and the best for the Ring Metal/Metal with 5% revision at 17 yrs.7
It is now accepted that a Charnley type total hip replacement can give perfectly satisfactory results in an elderly inactive population. The results published are a reflection of the quality of the surgical procedure with good results (failure of below 1% per year) reported from specialist centres.6,8,9,10 Less good results are reported from general hospitals, with 9% revision at 5 years and 27% of patients having a poor outcome. 11 (Trent Regional Arthroplasty Study)
