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MODERN METAL-ON-METAL HIP RESURFACING A TECHNOLOGY OVERVIEW

My View:

  • A very academically correct document but extremely ass-covering in my view.
  • You need a PhD to read this paper – then it didn’t help me too much – gave up and started reading the pictures – worth a thousand words, after all.
  • Some the text made sense but the pictures are better!
  • BUT this did make sense – Analyses conducted by three joint registries conclude that overall patients who receive hip resurfacing (HR) are at greater risk for revision than patients who receive total hip arthroplasty (THA).

You should really take a quick look at the graphs below – very interesting and I have added my views on them

What they said…

SUMMARY OF PUBLISHED RESULTS

The available literature on hip resurfacing (HR) is not of high enough quality to be conclusive. Bearing this in mind, summaries of the data that pertain to the four key questions addressed in this Technology Over are summarized below:

QUESTION #1: ARE REVISION RATES DIFFERENT AFTER METAL ON METAL HIP RESURFACING THAN TOTAL HIP ARTHROPLASTY?

Analyses conducted by three joint registries conclude that overall patients who receive hip resurfacing (HR) are at greater risk for revision than patients who receive total hip arthroplasty (THA). The Australian registry, however, suggests that younger males with osteoarthritis might have a lower revision rate after HR than THA. The available data, however, does not clearly establish such an advantage for this subgroup. 1-3 This may be the case because multifactorial analysis is required and the bulk of the analyses in these registries is limited or single variable analysis. Subgroup analyses of interest that require further investigation include the following:

  • Hip resurfacing and THA patients with a diagnosis of osteoarthritis. Subgroup analyses suggest these patients are at the lowest risk for revision.
  • Gender- related differences. The most recent registry reports differ on whether women are at greater risk for revision than men after hip resurfacing or after THA. Two registries find no gender-related difference and a third registry finds that women who received hip resurfacing and men who received THA were at greater risk for revision.
  • Age related differences. The most recent registry reports also differ on whether a patient’s age influences revision rates after hip resurfacing or after THA. Therefore we cannot conclusively comment on whether a patient’s age influences revision rates after hip resurfacing or after THA.
  • Component Size. Smaller components are at greater risk of revision than larger ones. Similarly, different implants may produce different clinical results, meaning that implant type must be considered in all analyses. The results of studies that do not consider this variable are difficult to interpret.

Rigorous multifactorial statistical analysis has not yet been conducted that would allow determination of whether one particular type of patients fare better than others with HR. Such analysis must simultaneously account for the effects of all patient and device characteristics of interest and also take into account any interactions between relevant variables. Current data may also be influenced by significant surgeon bias and patient self-selection regarding the current perceptions of the ideal candidate for HR with THA remaining as the default alternative for less ideal candidates.

Treatment is always based on the assumption that decisions are predicated on physician and patient mutual communication with discussion of available treatments and procedures applicable to the individual patient.

QUESTION #2: IN ALL PATIENTS WHO UNDERGO HIP RESURFACING AS COMPARED TO CONTEMPORARY TOTAL HIP REPLACEMENT, WHAT PATIENT CHARACTERISTICS BEST PREDICT SUCCESSFUL/UNSUCCESSFUL OUTCOMES?

  • The literature on prognostic indicators does not conclusively demonstrate predictors of better or worse patient-oriented outcomes (e.g. pain relief, patient satisfaction, walking ability) for either resurfacing arthroplasty or THA.

QUESTION #3: WHAT IS THE MORE EFFECTIVE TREATMENT: HIP RESURFACING OR TOTAL HIP REPLACEMENT?

  • There is limited data directly comparing efficacy of hip resurfacing and THA. The disparate pre-operative hip function scores and demographic characteristics between the groups enrolled in the relevant comparative studies prohibits meaningful comparisons and confounds the interpretation of the data.

QUESTION #4: IS THERE ANY EVIDENCE THAT IMPROVEMENT IN TECHNIQUE OR PATIENT SELECTION FOR HIP RESURFACING WILL RESULT IN IMPROVED OUTCOMES?

  • Low quality studies suggest that outcomes after hip resurfacing can be improved by changes in technique and increased surgeon experience.

Now for the Pictures!

  • Clearly Australia is the least hazardous place to get your hip replaced…
  • Hip Resurfacing is higher risk of revision – but this makes sense because it is principally used in younger patients.

In the figure below AVN and DDH are much less common – OA = Osteoarthritis and the cumulative rate of resurfacing is about 4-5%.

Seems to suggest that if you have a more uncommon reason for a hip replacement that you should not go for a hip resurfacing – go for a total hip replacement – safer.


This graph tells much the same story – safer to have a total hip replacement overall!

This is VERY interesting – women have a higher rate of revision surgery after hip resurfacing. Wonder why?

And this one seems to suggest that hip resurfacing in the over 75 years bracket has a 1 in 10 chance of needing to be revised. Forget resurfacing once you are past the mid 60’s seems to be the message.

Figure 6 confirms that view – total hip replacement is way better than hip resurfacing.

Except possibly for younger women – but this would be a marginal call.

Doesn’t seem to make much sense with men – insensitive bastards!

Figure 9 suggests resurfacing is NOT the way to go.

And if you needed proof look at Figure 10 – the bottom black line is for resurfacing – way worse than for total hip replacement.

And it seems that cemented or hybrid cemented is much better than uncemented.

Figure 11 removes all doubt – hip resurfacing is not the way to go. Some of this may be that many surgeons are not so familiar with resurfacing technique and so have a higher chance of getting it wrong?

Figure 12 says it again – cemented wins – hip resurfacing loses!


An Figure 15 says “bigger balls are better” or should I say, bigger femoral heads reduce the rate of dislocation. Less than 50 mm is a problem.

More data in Figure 17 supporting the need for a bigger femoral head.

Ditto in figure 18.

Interesting in Figure 19 – suggests that no real difference in metal-on-metal hips?

But there is some difference with smaller heads in Figure 20 – metal-on plastic.

This table is really interesting – Dislocation, loosening and fracture are the main reasons for revision of a total hip replacement – about 70% of the time.

But 65% of the hip resurfacing revisions relate to loosening and fracture! Dislocation doesn’t figure much, probably due to the larger femoral head size. Pain doesn’t seem to be an issue in Australia.


But pain is 23% of the issue in England and Wales with hip resurfacing revisions – and fracture and loosening the other big causes of revision. Again dislocation is way less than for the THA.

Data from Sweden is not much help – less than one percent are resurfacings in Sweden.

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