Derek McMinn on approaches:
11/07/07
I started back in 1991 with the antero-lateral approach to the hip for resurfacing. At that time we were worried about blood supply to the femoral head and on theoretical grounds the antero-lateral approach preserved the blood supply well. For many patients the approach was satisfactory but there were some problems. The exposure obtained in large patients was not good. This meant that heavy retraction had to be used, and heavy retraction caused trauma to muscle and other soft tissues which in turn led to heterotopic ossification. The other problem was that some patients had a permanent limp after my surgery as a result of the surgical approach. Please understand that the instruments were crude back then compared to today where newer designs of instruments would cause less tissue trauma and make the antero-lateral approach a better option. The sight of limping patients persuaded me to change my approach to the posterior approach. The theoretical objection to this approach was that it may cause more damage to the femoral head blood supply. It turns out that the problems with femoral head blood supply using the posterior approach are very rare, as you heard at the conference. The big advantage is that an excellent exposure can be obtained, giving the surgeon the best opportunity for perfect component positioning. As you heard, inaccuracy with respect to acetabular component positioning is badly tolerated and a high acetabular component inclination angle is the single biggest reason for early bearing failure following a metal on metal resurfacing. The other great advantage is that very little trauma to the soft tissues need occur with a posterior approach resurfacing. The other thing is that a mini-incision posterior approach can be done by those surgeons experienced in the resurfacing operation with good exposure and minimal tissue trauma. My unit published our mini-incision resurfacing results a few years ago, the average incision length was under 12 cm and measured component position was good. 
There are two other surgical approaches to be considered by surgeons, but for different reasons these are not reasonable at this time.

Dr. Vijay Bose on approaches:
There are two ways to look at approaches to hip resurfacing or any hip arthroplasty. One is to view it with the amount of muscle damage done. The other is to view it in respect to the blood supply or the vascularity. The post approach is traditionally known as the muscle sparing approach and the anterior and anterolateral approaches are the muscle compromising approaches. These approaches are known as Hardinge approach or London hospital approach. There are many more modifications of this with slight variations but essentially they are the same and they disturb muscles to varying extents. The muscle here refers to the Abductor group or the muscles which lift your leg sideways and is the most important muscle of the hip. The post approach spares this completely. Interestingly there is now an anterior approach which is getting to be very popular for mini -THR and this is known as the mini Watson Jones approach or the micro hip approach. This does not disturb the abductor though it a ant. approach. However resurfacing cannot be done through this approach. Even when one does a THR the head has to be sawed off in place and then delivered out separately. Or in other words the hip cannot be 'dislocated' through this approach which precludes hip resurfacing. However some muscle have to be cut in any approach to get access to the hip and in the post approach, one cuts the short ext rotators which are flimsy, small muscles in the back of the hip. These are stitched back. These muscles are relatively unimportant. It is largely accepted that the post approach is more conducive to early and complete return of function as it is muscle sparing. The ant approaches which disturb the gluteus medius will result in slower and incomplete return of function depending on the amount of muscle disturbed and the intactness of the muscle repair over long term. The younger and the more active the patient, the more would be the perceptible difference between the ant and post. approaches as regards function. Thus an elderly patient having a THR will appear to have the same result with either approach whereas a young patient having a resurfacing will have an obvious difference.

Michael Freeman, an English surgeon established in 1978, the fact that the blood supply in an osteoarthritic hip is different from a normal hip. In full blown arthritis the blood supply to a large extent changes to inside bone( intra-0sseus) from a pattern that is predominantly outside bone (extra osseus ).Therefore in osteoarthritis, any approach can be attempted without a risk to the blood supply. Hence in osteoarthritis, as the blood supply issue is taken out of the equation only the muscle damage is relevant and therefore post approach is better. In fact when Derek McMinn developed modern resurfacing, he first attempted it through the anterior approach and found so much of muscle damage that he decided to change to posterior.

However in non-OA indications like AVN, the situation is little different and the intra-osseus blood supply is not well developed. Increasingly it is becoming increasingly obvious that neck capsule preservation is vital in these non-OA indications. Hence we have developed the neck capsule preserving ( NCP ) approach where the end arteries to the neck and head -neck junction has to be preserved. We have been doing the NCP approach for the last 6 yrs in predominantly non-oA indications with excellent results.

Neck capsule preservation is not possible through the anterior approach and therefore the post approach is more suited for non-OA indications. The other benefit of the NCP approach is the fact the capsule is also repaired back completely so that the surgeon can confidently advise patients that there wont be any restrictions post-op. The repaired capsule will prevent the patient from doing any awkward movement even inadvertently. This is very useful in the first 6 weeks which is the time taken for a pseudo capsule to form when the surgeon does not stitch back the capsule. Therefore capsule repair is of relevance only in the 1st 6 weeks.

The 3rd issue comes into play when a femoral component of a resurfacing is done uncemented. This is the situation where one has to be extraordinarily careful as even a little necrosis of the head bone would cause failure of the implant. When one uses cement, the cement converts the head into a 'composite' of live bone, dead bone and cement. Some bone unviablility is easily tolerated due to the presence of cement. Therefore in uncemented femoral resurfacing one has to use the Ganz approach or surgical dislocation where the blood> supply should preserved entirely. Although this appears to be desirable in theory for all resurfacing it has its own problems. It involves a trochanteric osteotomy and reattachment with screws. The pt has to be partial weight bearing for 6-8 weeks till the ostetomy unites. Prof Ganz from Berne developed this approach for non arthritic hips for pts in their 20s to treat femoral acetabular impingement (FAI). These patients have a completely normal pattern of blood supply (completely exta-osseus) and in spite of this, pts do not develop any problems. This technique is described as surgical dislocation and surgeons employ this for any condition that requires a dislocation of a normal ( non-arthritic) hips. The surgical dislocation is always done posteriorly.

Thus 3 different situations with regard to resurfacing need 3 different approaches and all of them are posterior! Anterior or posterior refers to which side the hip is dislocated and not on where the incision would be. Irrespective of whether anterior or posterior approach is done, the incision will always be on the side ( exactly lateral). So one cannot deduce approach employed by looking at the incision. Therefore the skin incision is same for both approaches.

Also sent to me March 2007 from Dr. Vijay Bose:
Hi Vicky,

Thanks for your mail and continued support for the cause. I was amazed at the depth of your knowledge when i was speaking to you here. I am sure many orthopaedic surgeons do not have as much information on the subject as you do. Keep it up.

No it was not Paul who did the paper on ant approach. He believes that resurfacing must be done through the ganz approach which preserves blood supply even more than the neck capsule preserving approach. However it has the disadvantage of needing to do a osteotomy of the bone which would be fixed with screws. This will necessitate 6 wks of partial wt bearing.

We have found that this to be unnecessary and preserving the end arteries by preserving the capsule is adequate.

The ant approach was used by Mcminn when i was in Birmingham. We had such a high incidence of ectopic ossification that we were giving post-op radiation for all patients. Initially we thought that ectopic ossification was due to the resurfacing procedure itself. After we shifted to the posterior approach, the incidence became negligible and it soon became obv. that the ossification was related to the approach and not the procedure per se. This has not been published to the best of my knowledge.

It is important to note that hip resurfacing can be done through the anterior approach as well and some surgeons are better in doing this than others. However when one sees this being done by the ant approach the 'struggle' to expose the acetabulum with the intact head is quite obvious. This struggle can cause muscle damage at times.

with best regards, vijay bose, chennai

Dr. Gross
I estimate that most total hip resurfacing done worldwide is done through a posterior approach ( > 90 %). There was an interesting report recently at the Annapolis MD HSR Meeting from Mr. Ronan Treacy indicating no difference in results between posterior and anterior-lateral approaches in a direct comparison looking at the rates of limp and other complications. Therefore, I do not think anyone has shown that it really matters which approach is used. My current personal preference is posterior minimally invasive (see my video) vascular sparing (as described by Dr. Koen DeSmet). I believe, that with this approach, I can accomplish the operation in virtually all case that are candidates ( only 2 of 1300 converted to THR intraoperatively), return patients back to activity as rapidly as possible, avoid a permanent limp, and place components in ideal position. This is personal preference, not science. Every surgeon should use the approach that he/she is most comfortable with.

Dr. Su
I like the posterior approach for the excellent exposure that it provides (which is critical for the positioning of the implants) and the ease of recovery for the patient.  There are some who believe a trochanteric flip (Ganz osteotomy) or anterolateral approach weight bearing and avoidance of certain movements. Finally, if the muscles that were detached during the anterolateral approach don’t heal back to the bone, then this can be a serious problem.  I don’t have much experience with the anterior approach, so I can’t really comment on that.

A final word is that I think there are many ways to skin a cat, and surgeons should use what they feel comfortable with.are better for the blood supply, but we saw from Mr. Treacy’s data that there wasn’t any difference in outcomes between the posterior and anterolateral approaches. Also, the recovery from the anterolateral and trochanteric flip tend to be more difficult, with protected.

Direct Anterior approach?
I think the direct anterior approach is intriguing in that it is an intermuscular approach, without cutting or detaching any muscles. However, I have witnessed it before and found it to be a struggle with a limited exposure. The potential advantage is a preservation of the blood supply to the femoral head, but as we have discussed before, the NCP approach to the hip via the posterior may be able to do the same thing.

I think the posterior approach is more suitable for the majority of patients because it gives the best visualization for component positioning, can be easily extended, and offers just as quick a recovery.

Dr. Brooks Updated on 4/9/11
I trained exclusively in the posterior approach for THR as a resident, and switched to the anterolateral approach in practice. I have used it exclusively in THR for 25 years, and in resurfacing since 2006. I have seen the direct anterior approach but have no experience with it myself.
My preference for the anterolateral approach is due to several issues.
 
1. The exposure is easy in either the posterior or anterolateral approach, but both the acetabulum and the femoral head are anterior-facing structures, so it is more logical to use some type of anterior approach. If you want to look someone in the eye, face them. In addition, the most common resurfacing situation I see is in a male with femeroacetabular impingement, who usually has a large femoral neck osteophyte anteriorly. Anterior exposure makes it very easy to reshape the anterior neck. I'm looking right at it. Almost every patient has a contracture of the anterior capsule, (flexion contracture) which is automatically and safely dealt with through an anterior approach.
 
2. The way I (and others) do an anterolateral approach, no muscle is cut transversely, across its fibers. The important abductors of the hip are split in line with their fibers, and those fibers blend over the trochanter eventually becoming continuous with the fibers of the vastus lateralis (quadriceps), an inch or so of which is split as well. Thus, an entire continuous sleeve of muscle and tendon is elevated as one sheet from the anterior hip capsule. Suturing afterwards then involves only side-to-side closure, and nothing needs to be repaired end-to-end. Side-to-side means that subsequent muscle contraction has the effect of closing the repair, not tugging on it. Contraction of the abductors and the quadriceps balance each other so neither muscle group has any tendency to pull away. This is in contrast to other versions of the anterolateral approach that I have seen where substantial portions of the abductors are indeed cut transversely. This needs to be carefully repaired, because any contraction with weight-bearing pulls on the suture line, and it may or may not heal properly. If it pulls apart you can get limping.
 
3. In a posterior approach, several relatively unimportant muscles are cut transversely, and repaired end-to-end. These include the piriformis, obturator internus, gemelli (two), quadratus femoris, and obturator externus. Many surgeons also cut the Gluteus maximus tendon to a greater or lesser extent. This is done more in resurfacing than in THR due to the greater exposure needed, and the fear of compression of the sciatic nerve by this tendon during rotation of the hip. G Max is not an unimportant tendon. It has to be repaired end-to-end, and as with anything else, subsequent muscle contraction tugs on this repair, which may therefore fail. So when all is said and done you may have 7 muscles cut transversely and repaired end-to-end. Is that OK? Yes, of course it is, as long as it is done right. Like everything else.
 
4. The posterior approach also cuts the posterior capsule. This should be repaired, in order to minimize the already low risk of dislocation with resurfacing. The anterloateral approach does not cut the posterior capsule. Dislocation is not an issue at all. We use no "hip precautions" such as avoiding certain positions, crossing of legs, twisting, or raised toilet seats.
 
5. The blood supply of the femoral head is largely posterior, with or without osteoarthritis. (Freeman's teaching not universally accepted). Multiple studies show that the blood supply is routinely disturbed using a posterior approach and not using an anterolateral approach. Certainly that cannot matter for THR, where the head is gone anyway. Oddly, good long-term studies from the UK show that it does not seem to matter in resurfacing, where it should matter. One might have thought that late femoral component loosening could occur with avascular necrosis of the reamed head. One could also think that femoral neck fracture, a result of accumulated non-healing microstresses (fatigue failure), would occur more in avascular bone than in living bone. The bottom line is that it doesn't seem to make a difference, but it should.
 
6. I don't like trochanteric osteotomies. Another entire set of complications comes up, especially trochanteric non-union, lateral hip pain, and hardware issues.
 
7. I haven't had a lot of limping. My guess is that it could be related to the details of the technique and newer instruments such as retractors that do not require much force with less muscle or nerve damage.
 
8. I haven't had a lot of clinically significant heterotopic bone, 0.2%.
 
In summary, I have looked at all the approaches and choose to do the anterolateral approach. My advice to patients is definitely do NOT shop around for a particular approach, as any approach will do beautifully as long as it is done right, and the converse is sadly true as well. Find a surgeon with experience in whom you have confidence, and he will do what works best in his hands. It's like getting on an airplane. At some point you just have to trust the pilot.

Dr. Clarke
I use the posterior approach because it provides the best exposure for me and because it has been associated with excellent results for hip resurfacing. I have, however, used other approaches in the past including the antero-lateral approach and a less invasive medial approach through an incision hidden in the groin.

Direct Anterior approach?
This approach has theoretical advantages, but I will stay on the sidelines for now.  I am personally concerned by the potential for inadequate acetabular fixation or component mal-alignment as a result of inadequate exposure. This is an exacting operation and the published results when done through the posterior approach are a compelling reason to stay with that approach.

Dr. Schmazlried
Like any surgical procedure, it is more about who does it than what is done.  I think that a good, experienced surgeon will get good results – after some learning curve. There is no comparative data.   
Thomas P. Schmalzried, M.D.

Dr. Kelly
I use the posterior approach to the hip for resurfacing arthroplasty for a couple of reasons. It is felt to be a 'muscle sparing' operation which in younger and more active patients is advantageous. The other reason is that it is the approach with which I am most familiar. It gives me the ability to place the components in their appropriate location/alignment with the best visualization. I believe that either approach is acceptable and that a surgeon should use the approach that is most familiar/comfortable for them to implant the prostheses appropriately.

Dr. De Smet
Anterolateral I did for 5 years in over thousands procedures. Have stopped this because of abductormuscles problems!!!

Direct Anterior Approach?
It is not a new technique used already for more then 40 or 50 years. There is only one centre well known for this Technique in Paris, namely group of Prof. Judet. It should not touch any muscle. For total hip OK, but new technique for a lot of people and again a learning curve. Other downside is need of a traction table (possible other problems, some people had even ankle fractures!) and problems is heavy and muscular people! The exposure is just less as with posterior approach!! The problem with anterior is just like mini invasive it is FASHION, try to make a new publicity stunt. One thing is sure to do RESURFACING with a direct anterior approach it is asking for problems (70% male, muscular patients!!). You will have again probably to opposite parties in this technique to make the other one feeling or showing badly and nobody telling the true story in between.

Dr. Rogerson
The most important reason I use the posterior approach is to spare the gluteus medius and avoid an abductor lurch after surgery which is fairly common with a lateral, antero-lateral and to a lesser extent anterior approach. Patients who desire to get active again are very dissatisfied if they have abductor weakness; if you detach a portion of the gluteus medius then you really have to protect its repair for 6 or so weeks after the surgery as Paul Beaule does. Another reason I like the posterior approach is the exposure one can attain for the femoral head and the ability to effectively use the stylus to get the guidewire in exactly the right position.

Direct Anterior approach?
I'm familiar with Joel Matta's and the French anterior approach using the special table but have only seen it utilized for THA and not Resurfacing yet.  In the posterior approach you worry about traction on the sciatic nerve but in the direct anterior approach you are pushing the head posteriorly and doing some posterior capsular release (by necessity for a resurfacing) so one would still be potentially compromising circulation and risking direct pressure on the sciatic.  That being said, I would still like to see an actual video of the direct anterior for resurfacing and am attending the L.A. course Oct 24-25 where all the approaches will be examined.  More later.

Dr. Michael Mont
The choice of approach to use for resurfacing has received much attention and I believe extra “hype.” In multiple studies now published, there are no reported clinical differences in the short term and up to ten years of follow-up between anterior and posterior approaches.  I believe that any approach can be used and the surgeon should use what they feel most comfortable.

Short-term differences that patients may report with either approach have to do with other factors in my opinion. I use the antero-lateral approach because it affords me easy exposure, lower dislocation risk, less chance to disrupt the blood supply of the femoral head—among other reasons. However, I have no problem with posterior approaches and am currently working on and performing an even more minimally invasive anterior approach in selected patients. Again, I would repeat that a recent prospective randomized study showed no differences in all three approaches.

In summary, the reasons I use the anterolateral approach are as follows:

1. easier to perform
2. less chance for dislocation
3. no difference in posterior approach at six months to one year or in long-term studies
4. increased range of motion from not having to repair the capsule
5. multiple studies showing decreased effect on femoral head blood supply

Presently, I’m performing an anterior approach which does not go through any muscles.

Dr. Amstutz
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 posterior approach for hip resurfacing has the following advantages now that the instrumentation has been redesigned specifically for that approach:

1. No important muscle groups are sectioned.
2. There is no release of the abductor muscles. They are the most important muscles stabilizing the hip during walking and other activities.
3. The gluteus medius and minimus remain intact. The only muscle groups that are released are the short rotators that are repaired at the conclusion of the procedure. However, no important gait or other disturbances results from a release even if they are not repaired because the rotation is accomplished by other muscles. One of the two insertions of the gluteus maximus tendon which extends the hip may be released and if so then repaired. The other insertion remains intact and there has been no significant physiological damage to date.
4. The new instrumentation facilitates a smaller incision especially in thin individuals. A longer incision is necessary in well muscled or overweight patients. A slightly longer incision is necessary in resurfacing than when the head and neck are amputated in conventional THR. In hip resurfacing the surgeon must work around the head and neck to be able to prepare the acetabulum and implant the socket accurately. Hip resurfacing is technically more demanding and takes slightly longer. Since hip resurfacing is an anatomical replacement, leg length equalization is facilitated and more precise. Leg length equalization in THR is more demanding, less certain and requires an intra-operative X-ray.
5. The anterior approach requires removal of some of the abductor muscles for either hip resurfacing or THR. Even though they are repaired this reattachment may not be 100% successful.