Surgeon's Opinions About Hemi-Resurfacing

[Pat Walter]

I am starting a new topic where I will post each surgeons response about hemi-resurfacing.   I have asked the most experienced hip resurfacing surgeons to make a statement about hemi-resurfacing. Their responses will allow us to learn why hip resurfacing has become so popular while hemi-resurfacing is rarely used or suggested.

[Pat Walter]

Hi Pat,

Thanks.

Hemi resurfacing in theory appears to be an atttractive idea. However experience has proved otherwise. In a hemi resurfacing, the metal cap articulates with the natural articular cartilage of the acetabular socket. This 'bearing" works reasonably in elderly inactive patients and fails rapidly in someone with an high activity level.
 
The metal on cartilage bearing is commonly use in a hemiarthroplasty of the hip which is done for femoral neck fractures in the elderly. This is probably one of the commonest procedures in orthopaedics all over the world. Elderly, sedentry  patients have a high incidence of femoral neck fractures and typically they would receive a hemi arthroplasty. However if someone is a little younger and more active a hemiarthroplasty will cause destruction of the cartilage ( chondrolysis) and pain and it has to be converted to a THR. I have done many of these conversions. Therefore the world over surgeons would do a THR straight away in femoral neck fractures if the patient has a higher activity level.
 
Since resurfacing by definition is for younger active people, the metal on cartilage bearing is at a high chance of early failure. ( there have been some exceptions). Hence I would not use it in my practice. Some surgeons would argue that if the cartilage fails then they would convert to a total resurfacing. While the argument is valid in theory, technically a conversion of a hemi to a total resurfacing is complex.
 
I hope that this clarifies the issue.
 
with best regards
 
vijay bose
chennai

[Pat Walter]

Dear Pat,
       
The indications for hemi-resurfacing are quite narrow.  The joint disease should be limited to the femoral side, such as avascular necrosis or trauma - but without evidence of acetabular cartilage degeneration (narrowing of the joint space or development of any bone spurs).  The pain relief is unpredictable and generally not as good as with a total hip resurfacing.
 
Thomas P. Schmalzried, M.D.

[Pat Walter]

Dear Pat

Koen De Smet ANSWER/ANTWOORD] In the US for long they were doing hemiresurfacings because full resurfacings were not working well and the Metal on Metal resurfacing was not FDA approved yet. The results indeed are not so good. The hipscores after a time are certainly not perfect, not what we can get with a total resurfacing!

The hemiresurfacing also is only kept for people with an avascular necrosis of the hip, not for any other condition, so the indication is not so big. The problem in these cases is that after time the metal head that is resurfaced will give osteoarthritis symptoms because it is wearing out the cartilage of the acetabulum. If the patient has had a hemiresurfacing that is a component that matches with a total MOM resurfacing and the size of the head is not put too big, they can have a full resurfacing done with the head implant kept on! Unfortunately this is not always possible and most of the time not possible.

There are indeed cases that can stay long with this device, hemiresurfacing, but it is certainly the minority.

Looking into the indications to do a hemi, avascular necrosis is known to be a condition that gives the less good results in any prosthetic implant. (In my series with resurfacing and ceramic on ceramic in young people I can not state or proof this)

Greetz
KOEN
Koen De Smet
AMC Gent
Anca Medisch Centrum - Anca Medical Center GHENT
Hipsurgeon
Krijgslaan 181
9000 GENT
BELGIUM
www.heup.be
www.hip-clinic.com
+3292525903

[Pat Walter]

Pat,
 
One would expect a hemi resurfacing to not get as effectiver pain relief as a complete BHR because the socket still has nerve and bone exposed.  Hemis have been done in the past for AVN since the socket is essentially normal but the pain relief is usually only about 85% and that is with a good acetabulum.  In general, most orthopedists are shying away from hemiarthroplasty because of this pain issue.  One would expect even somewhat less relief if the socket is degenerative.  Hemi resurfacing of the shoulder (Copeland) is fairly common but one gets less than complete pain relief in this setting also even though the shoulder is not nearly as much of a weight bearing joint.

Happily, if pain is still an issue for this person, the cup can still be converted to a BHR metal socket and still keep the present head if the position of the head component is correct. 
 
Sincerely,
 
John Rogerson, MD

[Pat Walter]

What is the Role of Hemi-resurfacing?

It is my opinion that there no longer is any role for this procedure. The FDA does not realize this; they continue to approve implants for hemi-resurfacing. Typically these femoral hemi-resurfacing implants are best used off-label together with an acetabular component for total resurfacing. This highlights the fact that the FDA is not a good source of information when it comes to orthopedic expertise.

Hemi-resurfacing refers to resurfacing only the femur and letting this new metal surface rub against the cartilage or bone of the acetabulum. This is a bad idea.

There used to be one reasonable indication for hemi-resurfacing: the young patient with stage III Osteonecrosis. This means that the femoral head has collapsed, but the acetabulum has not yet developed cartilage deterioration. Hemi-resurfacing in this type of patient typically improves symptoms significantly, but does not give as good or as predictable pain relief as standard total hip arthroplasty. After the new metal head rubs on the acetabular cartilage for a few years, the cartilage wears out and the pain increases.

So why would any surgeon advise, or any patient choose hemi-resurfacing?

The answer is that in a young patient it may make sense to accept a less than perfect result (as far as pain relief goes) in exchange for bone preservation. Especially in the past era where metal-on-plastic bearings had a 30% failure rate in young patients at 8 years often with extensive bone loss due to osteolysis. Hemi-resurfacing in this scenario did make some sense.

The options now have completely changed. Now we have a number of modern bearing options for total hip arthroplasty and we also have metal-on-metal hip resurfacing. Failure rates in young patients with these options are 5% at 8 years without much osteolysis.

If the goal is bone preservation, then a total hip resurfacing is the operation of choice. For stage III Osteonecrosis, it now makes much more sense to also resurface the acetabulum and perform a total hip resurfacing rather than a hemi-resurfacing. The pain relief is much more reliable and the result is longer lasting than for hemi-resurfacing.

The only problem is implanting an acetabular resurfacing component with the femoral head in the way. This technically challenges the surgeon’s skills. Fortunately there are now numerous surgeons worldwide who have developed the skill required to do this routinely with a very low complication rate.

A patient with a modern hemi-resurfacing could probably be converted to a total resurfacing. Most modern components are manufactured to standards that would allow combining them with an acetabular component to convert to a total resurfacing. The hospital implant record would provide the necessary information to make this determination. Older hemi-resurfacing components were not manufactured to specifications to allow metal-metal bearing, and would need to be revised to total hip replacements if they were sufficiently painful.

Thomas P. Gross, MD
Grossortho.com
12/16/2008