Hip Resurfacing…what are the facts?
Modern Hip resurfacing was introduced in 1997 by a Birmingham surgeon called Derek McMinn, who basically looked at two old prostheses, the Judet hip from the 1950s, and the McKee-Farrar metal-on-metal hip replacement of the 1960s and combined the two to make the modern hip resurfacing. It is still a hip replacement, but unlike “traditional” replacements, it consisted of a metal cup in the pelvis and a metal cap on the head of the thigh bone. It is sometimes referred to as a partial hip replacement but in reality, it is a complete hip replacement.
A resurfacing is a ‘metal-on-metal’ (MOM) implant. This refers to the two surfaces that rub against each other when the joint moves. Historically, for its time, the McKee-Farrar had very good survivorship, and so the idea was that metal bearings would last much longer than the other bearings of the time (metal-on-plastic or ceramic). Resurfacing tends to be more stable as the head which goes on the femur is very large, so the risk of ‘dislocation’ was less. This reduced wear and increased stability opened up the option of hip replacements to younger active patients, as the feeling at the time was that this type of implant would reduce the need for revision or repeat surgery, which is more complex, higher risk and likely to have a poorer result than a first-time replacement. What was not appreciated, was that the neck (which is much wider than the neck of a standard hip replacement) could still catch against the cup and cause damage, which is essentially what happens with hip impingement.
Significant numbers were implanted in the late 1990s and early 2000s. Other companies saw they were missing out and so all the major implant manufacturers released a version (but all had to be slightly different due to patents). The original Birmingham hip resurfacing has done the best of all the various versions but unfortunately, some of these new designs did very badly. Actually, compared with standard hip replacements, they all had worse long-term results. This was because the metal-on-metal bearing actually wasn’t as safe as thought. Back in the 1960s, patients were not as active as now, and were in much worse condition prior to their hip replacement (which at the time was considered ‘major’ surgery) and so the issues with MOM didn’t really occur. Over time, it became clear that while the resurfacing did not produce as much wear as the traditional types, it did produce large amounts of very small metal particles which could cause very significant soft-tissue reactions and damage.
The problems associated with the MOM bearing became apparent around 2006 and as a result most companies dropped it and versions of it around 2007-8. The numbers of replacements implanted in the UK fell significantly.
Numbers of hip replacements implanted in UK by type
The current scenario is that a lot of NHS and private hospitals will not allow any form of MOM hip replacements (resurfacing or otherwise) to be performed. There are a few surgeons who still perform them as they believe that the failure rate is associated with the implantation technique, which is true to an extent but not wholly so. This situation continued until Andy Murray had his resurfacing early last year, which led to an increase in interest once again.
Technology has moved on since 1997, there are now far better contemporary styles of hip replacement which have all of the benefits of a resurfacing without the downsides and so the indications for resurfacing over anything else have essentially gone away. We specialise in hip replacements (with ceramic on highly cross-linked polyethylene) using robotics as I believe that technology produces the best outcome with the least complications and longest survival. For comparison, the revision risk of the type of implants we use at 14 years ranges from 3.77 to 5.28% compared to 14.78% for all ages of resurfacings, which rises to 22% in those under 55 years (see NJR).
At the Manchester Hip Clinic, we use either Accolade 2 uncemented stems or Exeter cemented stems (depending on age or bone shape) with Tritanium cups, all of which are made by Stryker, one of the big global orthopaedic companies. The bearing surfaces are ceramic on polyethylene, which has the least wear and best long-term survival on the National Joint Registry and we use Mako robotics to make sure they go in perfectly which gives excellent muscle balance and allows early return to function.
Most patients are in 2-3 days and off crutches by 2-4 weeks, exercise bike by 2 weeks and gradual increase in activity over 6-12 weeks. The dislocation risk is highest until at least 12 weeks but the hip will continue to improve for 10-12 months post-surgery. The fitter and stronger you are pre-surgery has a big effect on your recovery afterwards. We treat a lot of high-level athletes for both arthroscopy and replacement, so we are very pro-active with rehabilitation. It is important for us to liaise with your physio locally so we can monitor your recovery. If that is not possible, we can arrange physio supervision over Skype with our own team or one of our partner practices.
For more information see our UK national guidelines, the national joint registry report
and some information on our website…click HERE
By Prof Max Fehily and Mr Giles Stafford, London Hip Surgeon (click HERE)
