Approaches to Surgery

WHAT ABOUT NAVIGATION

Today navigation is still a tool that is not easy to use and that needs a certain learning curve as resurfacing itself also has.

So it is not a useful tool today for resurfacing beginners, where it should be! It would be nice if it would be a help at the start of the learning curve.

So can somebody with experience use it or should they use it?

It is like doing a certain approach and having experience with it, so it feels better and confident.

Most of the experienced surgeons do feel they do not need it. MAYBE it could help.

BUT there are some things that have to be cleared out still today:

*there is no correlation in most of the systems between head and cup.
*Most of the systems only look to the head, and nobody can tell us today what is now the best place to put the implant
*It would be the best to use it for the cup because there we have the most failures!

BUT AGAIN the most problems will be with females, that easily have twisted pelvis on the table and smaller sizes, and it is not sure it will have a big influence here.

If it is a system with preop CT of the pelvis to do the acetabulum, the pictures are taken in SUPINE (lying down position!). The patients walk and run on their hips, they do not lie on them, and that can make a complete difference!

So we are not there yet, if something could help me to do better surgery it would be navigation, but as it is today, it is not a 100% proven project. I have today so designed instruments that I call it navigation without navigation; of course in other sites navigation really could help!

I do not know if the 7 malpositioned cups in my series of 3000 would have benefited with navigation, possibly yes, but maybe would have had others where then the placement was worse?

It is the future?, maybe, but not there yet at present for everybody. That is why not everybody is using it, not just because we would be to lazy, to old, to stubborn or whatever.

If it would be used tomorrow in all cases from the start, the worry is also there, that if the navigation fails we do not know anymore what to do. All these facts should not be used for marketing or publicity issues but left to the orthopaedic community to make it better, try it and try to succeed better, what prof.Cobb, myself and all others I think try to do.

KOEN

koen de smet

hipsurgeon amc gent krijgslaan 181 9000 GENT BELGIUM +3292525903 www.heup.be

anca clinic roma valle giulia ROMA ITALY www.ancaclinic.it

There is some data indicating that navigation can improve the accuracy of femoral component placement in hip resurfacing.  The real issue is "compared to what?"  For an inexperienced surgeon, navigation may help him avoid component positioning problems that have been associated with "the learning curve".  However, for an experienced surgeon, who has an established mechanical alignment system with a high success rate - it is difficult to demonstrate an advantage to him with a navigation system.  Further, the registration process takes a little time – so the cost-to-benefit ratio for the experienced surgeon in a busy O.R. is questionable.  The navigation systems are not hard to learn to use, even for old guys like me!

A bigger challenge is acetabular component positioning.  This is true for total hips, and even more important for resurfacing.  There are 2 parts to the acetabular positioning problem.  The first is identifying the desired position for that patient and the second is putting the cup in that position.  Keeping the pelvis in one position and finding accurate pelvic/acetabular landmarks can be challenging.  The lateral opening angle is the easier part.  Most surgeons today agree that between 40 and 50 degrees is desirable.  Version is more complicated because the desired acetabular version is dependent on femoral version.  Acceptable version is also related to the lateral opening angle and the resultant bearing contact area.  Again, the issue is experience.

If I have any doubt about component positioning, I get an intra-operative x-ray.  Admittedly, there can be some challenges to getting a good intra-operative view.   For what it’s worth, we did an x-ray review of my first 500 resurfacings (minimum 1 year follow-up).  I have never had a femoral neck fracture and all sockets are below 50 degrees lateral opening.

Best wishes.

Thomas P. Schmalzried, M.D.

Computer aided navigation is an interesting concept. However, there is no evidence that it leads to better clinical outcomes and fewer failures. On the other hand, there is ample evidence that surgeon experience has a dramatic effect on outcomes and complications. 

One way to conceptualize this is that the experienced surgeon’s brain is a computer with much more sophisticated "software" than a navigation computer. When a computer is programmed, an algorithm must be created which has certain inherent limitations. Furthermore additional significant sources of errors are introduced by the registration of anatomic points for the navigation computer in surgery.

My personal opinion is that navigation that is based on a pre-operative CT scan data, which is being pioneered by Justin Cobb, has tremendous promise in the future to improve the results. At this point, we are still in the early development phase. It will probably add several thousand dollars to the cost of each operation. 

In summary, I believe the right kind of navigation surgery based on accurate 3D CT scans holds tremendous promise for the future. It will still require an extensive amount of preliminary development work before it is ready for routine use. 

I hope this helps with this very complex issue. 

Best regards,
Thomas P. Gross, M.D.

Computerized navigation has been around for a long time, in total hips, total knees, and now hip resurfacing. A lot of surgeons, including me, have tried it out and not seen an advantage in all but very exceptional cases. Yet other surgeons use it on every case.
 
This is what I think about computerized navigation: It is a tool which can narrow the "bell-curve" of component position, but the curve still has some spread. That helps a surgeon avoid "outliers", or badly misplaced components. Navigation does not make component position the exact same every time, but it helps avoid those outliers. (If it was the exact same every time there would be no bell-curve at all.)
 
So, if a surgeon has no outliers, in other words if he is doing a good job of keeping his personal bell-curve narrow, there is no advantage to using computer navigation. Alternatively, if a surgeon thinks he might accidentally misalign a component so much that it would be considered an outlier, the computer may prevent that.
 
Like any computer, what comes out depends on what went in. Registering the anatomy (which tells the computer where everything is) at the beginning of a computer-navigated operation is not at all an exact science, but depends upon knowledge and experience. It's the same with mechanical alignment jigs. With either method, one should hope that the surgeon is ready to adjust the verdict of the computer or the jig to place the component accurately in the bones which are clearly visible.
 
Are there any downsides to using a computer? Well, there is the extra time involved, which prolongs the surgery (think infections, blood clots). There is extra expense. There is often one more person in the OR, and more traffic in the OR can lead to infection. There is the possibility of surgical complacency if the doctor believes in the infallibility of computers.
 
I have heard this discussed at resurfacing meetings, and people whom I respect more than any others in this field have tried navigation and declared it "useless", and a "waste of time". While unwilling to go quite that far, it does make me think I am fine in continuing with mechanical jigs.
 
Your question about doctors not having 100% "retention" due to component malposition requires a reply. Personally, I have not had any failures in almost 600 resurfacings due to component malposition. I have 1 femoral neck fracture due to leg presses 8 weeks after surgery, and one pelvis fracture resulting from trauma 2 years after resurfacing. That's it. But malposition is an important cause of fracture, wear-related failure, and possibly pseudotumors as well, so should be avoided.
 
Any surgeon "young" enough to learn hip resurfacing is certainly young enough to learn the much easier task of computer navigation, so people who consider someone too "old" to learn navigation are being silly.
 
Similarly, a patient who would choose his surgeon based upon their use of computer navigation is badly misguided. There are many much more important issues to consider.
 
Having said all this, I wouldn't be surprised if at some point in the future surgical navigation becomes more accurate, easier, cheaper, and quicker. Robots will substitute for doctors. Surgeons will look back on the old days and shake their heads in amazement that we used to do all this by hand.
 
Peter Brooks MD, FRCS(C)
Cleveland Clinic

Using computer navigation in  joint surgery is a double edged weapon. While potentially it can reduce the number of outliers,  it can also cause tremendous deviations and absurd placements which would never be done with conventional jigs. I have seen many examples of this done elsewhere and referred to me for revision surgery.

Generally the input to the computer is made by a technique known as bone morphing where the surgeon uses pointer probes to point out the various bony landmarks to the computer. If the surgeon makes an error in this step then it obviously carries on in all further steps leading to a faulty placement. To argue that it removes human  error is most irrational.

We have the brainlab navigation ( market leader in navigation)  in our unit since 2007 and I did a series of cases at that time ( about 80 cases) . I have to say that the femoral cap placement was inferior to my placement with traditional jigs. However I found it useful when one had distorted anatomy as in previous prox. femoral osteotomy. I still use it for such cases.
 
There are many reasons in my opinion by which the conventional jig is far superior to the navigation in hip resurfacing.
 
1. bone morphing with the pointer probes damages the neck capsule which I protect passionately during hip resurfacing surgery and which I am sure is one of the key elements for my success rate.

2. I  use navigation routinely  during my Total knee replacements as the aim of the TKR surgery is to allign the components to the hip and ankle which are not visible in the surgical wound. In contrast in hip surgery the goal is not to align hip component to the spine , pelvis or knee/ ankle. The aim is to align components to local landmarks in the surgical wound, the location of which is given to the computer by the surgeon.  Then the computer gives back the same information which the surgeon offered in the first place. ( this is unlike the TKR where the computer picks up the hip on merely moving the hip and not morphing). Arguments that the computer increases accuracy in hip surgery is frankly absurd and have to be dismissed as marketing techniques.
 
3. The concept of incorporating the  combined anterversion is now the key in operating on FAI ( Femoro- acetabular impingement) which is the pathology in over 95 % of male patients having primary osteoarthritis. This is a dynamic assessment and can be done only with a jig using a lat cortex pin and cannot be done with navigation.
 
Having said all of the above  one must make a distinction between what Prof. Cobb uses and what others use.

Prof . Cobb is the  only one to my knowledge who uses a CT based navigation. The CT gives information which the surgeon cannot access unlike imageless navigation with all other surgeons which depends on surgeon's input based on bone morphing that  defeats the whole purpose of navigation.

In conclusion I would like to say that imageless navigation has very limited role in hip arthroplasty ( eg previosely operated cases) and is an excellent tool in Knee arthroplasty.
CT based navigation for hips which is still not available commercially ( which prof. Cobb uses) may have a significant role in hip arthroplasty. This has to be balanced with the radiation dose for routine CT to be applied universally( approx 30 -50 conventional x-ray dose )
 
wishing you the very best
 
with best regards
vijay bose
chennai

I am a 55 year old male. I have been active all my life in various sports which ultimately led to my hip cartilage damage. I had my right hip resurfaced using the anterior approach November 2007 by Dr. Stefan Kreuzer, a Birmingham hip. In Feb of this year, Dr Kruezer resurfaced my left hip with a Cormet.

I am almost two months into the recovery and I am almost back to full strength. There is still some numbness around the incision area, but I know from experience that will improve over time.

Dr. Kruezer is clearly constantly learning and improving as my second recovery is a few weeks ahead of my first.

My hospital stay was two days, I was walking the day of the surgery. I went home and used the walker for three days and never needed a cane. A week after my resurfacing, I was walking completely unassisted and even resumed normal activities like shopping, etc. Road biking is my passion, after one month I was training on a stationary bike; at five weeks I was back to riding my road bike albeit carefully; last weekend at eight weeks, I rode 80 miles in just over 4 hours.

I would strongly advise anyone considering hip resurfacing to find out if they are suitable for the anterior approach.


Nigel Church

Computer-Assisted Vs Conventional Mechanical Jig Technique in Hip Resurfacing Arthroplasty

Link  http://www.arthroplastyjournal.org/article/PIIS0883540307007292/abstract?rss=yes

Volume 24, Issue 3, Pages 341-350 (April 2009)

Jose Rafael E. Resubal, MD, FPOA, David A.F. Morgan, B.Sc(Med), FRACS, FAOA

Received 16 June 2007; accepted 17 December 2007. published online 15 February 2008.

Abstract
To compare the effectiveness of computer-assisted surgery (CAS) and mechanical jig technique in hip resurfacing arthroplasty, we reviewed 176 hip resurfacing arthroplasty performed in 158 patients. The initial 131 hips were resurfaced using the conventional mechanical jig technique, and the remaining 45 hips with the CAS technique. The demographic data of the patients were similar for both techniques. Follow-up radiographs taken 2 months after the surgery showed patients in the CAS technique having a significantly better alignment of the femoral component on the frontal and sagittal planes. There was no difference in the risk of implant notching on the femoral neck for both techniques. The implant sizes were similar for both techniques; thus, the amount of bone stock preserved was not technique specific.

Reprint requests: Jose Rafael E. Resubal, MD, FPOA, Suite 1, Level 8, Arnold Janssen Centre, Brisbane Private Hospital, 259 Wickham Terrace, Brisbane, Queensland 4000, Australia.

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Surgical Approaches for Hip Resurfacing
Peter Brooks MD
Cleveland Clinic

Most hip replacement and resurfacing surgery in the USA, about 80%, is performed through a posterior approach. About 20% of US hip surgeons prefer some variation of an anterior approach (antero-lateral, direct lateral, trans-gluteal, or true anterior). Anterior approaches are also more common in Europe and Canada.
 

In the posterior approach, the incision, dissection, and dislocation of the hip joint are all performed posteriorly (toward the buttock). The large gluteus maximus is split, and the gluteus medius and minimus muscles (hip abductors) are retracted, but not cut. A number of smaller muscles, the “short external rotators” including piriformis, obturator internus, gemelli, quadratus, and obturator externus, are cut, and the tendon of gluteus maximus may also be partially divided. With these out of the way, the posterior hip capsule is incised, and the hip is dislocated posteriorly by turning the foot toward the ceiling. The acetabulum and femoral head are then resurfaced, the muscles and capsule are repaired, and the incision closed.
 

In the direct lateral approach, (or trans-gluteal approach as it is also known), the incision is on the side of the hip, and from there the dissection proceeds towards the front of the hip joint. The hip abductors (gluteus medius and minimus) are split in the line of their fibers, peeled off the greater trochanter of the upper femur in continuity with upper fibers of the vastus lateralis, and retracted anteriorly, allowing the anterior capsule to be cut, and the hip to be dislocated anteriorly, with the foot pointing down to the floor. During closure, these muscles all tend to lie back where they belong, and since they have not been cut across their fibers, there is no tendency for their repair to pull apart. The antero-lateral approach is similar, but retracts or detaches, rather than splits, the abductors.
 

The true anterior approach can be adapted to hip resurfacing, actually better than for hip replacement, since exposure to the shaft of the femur is difficult (and not needed in resurfacing). It is not popular among surgeons who operate on adults, but is fairly common in pediatric orthopedics.

Different approaches have different issues. The posterior approach is very well known in the USA, and BHR developers Mr McMinn and Mr Treacy use it routinely as well. Theoretically it should have a higher dislocation rate, due to the fact that dislocation almost always occurs posteriorly, and this approach disrupts all the potential restraints to posterior dislocation. But dislocation after hip resurfacing is much less of a problem than it is with hip replacement, due to the very large head size. The blood supply to the femoral head stands a greater chance of damage through the posterior approach, since that is where the vessels mostly are. The important hip abductors (gluteus medius and minimus) are left completely intact.
 

The direct lateral (trans-gluteal) approach has the advantage of a lower dislocation rate, and less likelihood of damage to the blood supply of the femoral head. In addition, no muscles are actually cut across; they are just split, or teased apart in the line of their fibers, which should lead to more reliable healing. The exposure of the socket is a “straight shot”, since the acetabulum is an anteriorly facing structure. The disadvantages are that there is nonetheless surgical trauma to the abductors which, if substantial, could cause a limp. There are also reports of heterotopic ossification, although this may occur with any approach.
 

The true anterior approach can be associated with injury to a sensory nerve responsible for the side of the thigh (lateral femoral cutaneous nerve), and the location of the incision in the groin is not the cleanest part of the body. It is also by far the least commonly used of these incisions for adult hip surgery, so at least for the time being, we do not have a lot of data.
 

The main thing to keep in mind is that any of these surgical approaches can work just fine. All have been modified in many ways as surgeons find better ways to do things. The most important thing for a patient to decide is who will do their surgery, not how it will be done. The surgeon, drawing on his or her own training, experience and beliefs, will decide what works best in their hands.