Approaches to Surgery

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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.

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Clinical Orthopaedics & Related Research. 463:90-97, October 2007.
Cobb, Justin P FRCS; Kannan, Vijaraj MD; Brust, Klaus MD; Thevendran, Gow MD

Abstract:
Hip resurfacing is a novel technique with a substantial learning curve resulting in poor outcomes for many patients. We asked whether navigation would influence this learning curve and accuracy of implantation. Twenty medical students earning their degree in surgical technology participated in a randomized trial. We provided instruction about the surgical technique, including the use of conventional instrumentation, the use of a computed tomography-based planner for hip resurfacing, and a navigation system. The 20 students were then split into three groups undertaking these tasks in three different orders. Synthetic femurs replicated normal, osteoarthritis, slipped capital femoral epiphysis, and coxa valga. The mean error using the conventional method to insert a guidewire was 23[degrees]; using the computed tomography plan method it was 22[degrees]; and using navigation was 7[degrees]. Students produced similar accuracy, even in their first attempt, on difficult anatomy when provided navigation. Motivated students rapidly achieved an expert level of accuracy when provided with navigation. Learning a conventional method first did not improve performance, even in difficult cases. Our data suggest navigation may play an important role in reducing the learning curve in hip resurfacing arthroplasty and other tasks in arthroplasty in which a high degree of accuracy is clinically important.
 

(C) 2007 Lippincott Williams & Wilkins, Inc.
 

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Summary of Advantages - Posterior vs. Anterior Approach: ...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... READ MORE

What are the differences between the posterior and anterior surgical approaches?

Recovery is quicker with the posterior approach because no important muscle groups are sectioned. The posterior approach is also well-suited for patients who are large, well muscled or who require special techniques to implant the hip resurfacing socket.
To improve stability and reduce the incidence of dislocation after THR, some surgeons changed from the posterior to the anterior approach. Even a hip resurfacing procedure technically can be performed in most individuals using an anterior approach but this requires removal of 33% to 50% of the abductor muscles. Even though the muscle group is reattached, the muscles are strong and, therefore, the reattachment may pull loose even if activities are restricted for a prolonged period. Further, the data that indicates improved stability in THR with the anterior approach involved patients in whom the ball size utilized was very small (ie., between 22mm and 28mm). It is now possible, due to the newer, more wear resistant bearing technology, to use much larger balls and, hence, there is no advantage with the anterior approach. Wear data now available supports the use of larger ball sizes from 36 mm up to 54mm with Metal on Metal technology and up to 40 mm with new cross-linked polyethylene. The largest ball size available for ceramic on ceramic bearings is 36 mm because a two part socket is required and ceramic material must be relatively thick to minimize the risk of fracture.

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From: Vijay C.Bose
Sent: Friday, January 20, 2006 10:01 AM To: Vicky Marlow Subject: Re: Incision Hi Vicky , Thanks for the mail. All your queries are very relevant and I am happy that you have raised them... Yes, it is true that Minimally invasive approach has been proven not to have great benefits over a conventional incision in terms of blood loss, pain , or speed of recovery in the same surgeons hands. It is only of cosmetic value. All studies to investigate this have been done on two groups of patients in which a single surgeon employs the two approaches in the diff groups. When a surgeon who is capable of doing a minimally invasive approach does a conventional approach it is logical that the conventional technique will be only marginally bigger and therefore advantages do not show up in studies. However if a minimally invasive approach of a surgeon is compared with a conventional approach of another surgeon who never does minimally invasive or never makes an attempt to reduce his incision size (within comfort levels)- the differences will show up. When one compares an incision which is 5 cms for a particular procedure with another which is 50 cms for the same procedure - the differences will show up without any doubt. However to see objective difference between an incision which is 5 cms and 8 cms it is difficult This is a question of degree.MIS approach has been accused to be just a marketing trick which has caused more harm than good. This is true in many instances however one must be careful not to confuse MIS surgery with the concept of minimizing incision size. When surgeons are focused on doing a surgery with a pre- determined incision size like say 10 cms - they are hell bent on doing this through this incision even though they are struggling and probably getting many things wrong in the deep bone work. This is certainly not good. Scientific papers enumerating surgical disasters when this is employed is common place. The other side of the coin is when surgeons chop up patients to extraordinary lengths. Certainly it is equally wrong to cut up tissues unnecessarily when the same can be accomplished to the same degree of accuracy by employing a much smaller incision. In other words it is certainly the duty of the surgeon to minimize the length of incision of any elective procedure but ensuring that he is comfortable and deep bony work is not compromised in any way. There should not be any predetermined length but the surgeon must consciously reduce incision size as a guiding principle. Undoubtedly a hip incision that goes all the way to the knee will have many other bad effects apart from the scar.Therefore there is no doubt that surgeons must be constantly striving to reduce incision size without compromising any other factor. However trying to work with a pre-determined incision size is frequently a recipe for disaster. It is also well accepted that revolutionary techniques like the two incision technique for THR in which the surgeons previous experience with THR is rendered completely useless is very risky when compared evolutionary techniques in which surgeons reduce incision size progressively... READ MORE

Dr. Lichtblau of Quebec The anterior vs. posterior debate isn't going to be resolved by one study of electrode blood flow. Most surgeons would agree that blood flow to the femoral head (most of which comes backwards via the femoral neck) is theoretically better preserved through an anterior approach. Much of this info comes from the work of Ganz, who did a lot of cadaver dissection to prove this. Having said that, there doesn't seem to be any evidence whatsoever that one approach or the other leads to a higher incidence of the femoral head dying after resurfacing surgery (so called ''avascular necrosis''). McMinn and Treacy, who have together the largest series of resurfacings in the world, both use the posterior approach, and there have not been any problems seen yet. I prefer the posterior approach because I am good at it, and I can perform the surgery quite fast through this exposure. Bottom line is that your surgeon should probably use the approach he/she is most comfortable with. Hope this info is of help to you. Ethan Lichtblau, MD, FRCS(C) Montreal, Quebec READ MORE

Dr. De Smet of Belgium

Does the length of incision influence the rehabilitation?
No! A bigger incision does not mean that there will be more damage to the muscular structures. On the contrary, if you need a bigger incision to get better exposure, the placement of the implant can be done more precisely. Even with an incision of 30 cm you are able to walk well after 24 hours.
In the resurfacing procedure the incision is longer than THR (15 – 30 cm/6-12 inch) because of technical-anatomical reasons (saving the femoral head). The length of incision has no influence in the postoperative rehabilitation.
Which approach do you use?
For the resurfacing procedure I always use the posterolateral approach for technical reasons. For a classic total hip replacement I changed after having performed 1800 procedures from lateral to posterolateral approach as well. The posterolateral approach does have many advantages: the abductors (gluteus medius muscle) responsible for normal gait remains intact, so less patients suffer from permanent abnormal gait after hip prosthesis. There is a much better view to place the components in a more correctly way (very important for revision surgery). There will be less repetitive muscle damage in revision surgery; there are fewer patients with complaints of trochanteritis (irritation of the bursa) compared to the lateral approach. The only disadvantage of the posterolateral approach is the larger incidence of dislocations in inexperienced hands / learning curve.

 

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MIS Approach to Surgery by Dr. Bose

 

"Yes, it is true that Minimally invasive approach has been proven not to have great benefits over a conventional incision in terms of blood loss, pain , or speed of recovery in the same surgeons hands. It is only of cosmetic valueAll studies to investigate this have been done on two groups of patients in which a single surgeon employs the two approaches in the diff groups. When a surgeon who is capable of doing a minimally invasive approach does a conventional approach it is logical that the conventional technique will be only arginally bigger and therefore advantages do not show up in studies. However if a minimally invasive approach of a surgeon is compared with a conventional approach of another surgeon who never does minimally invasive or never makes an attempt to reduce his incision size (within comfort levels)- the differences will show up.

When one compares an incision which is 5 cms for a particular procedure with another which is 50 cms for the same procedure - the differences will show up without any doubt. However to see objective difference between an incision which is 5 cms and 8 cms it is difficult This is a question of degree. MIS approach has been accused to be just a marketing trick which has caused more harm than good. This is true in many instances however one must be careful not to confuse MIS surgery with the concept of minimizing incision size When surgeons are focused on doing a surgery with a pre- determined incision size like say 10 cms - they are hell bent on doing this through this incision even though they are struggling and probably getting many things wrong in the deep bone work. This is certainly not good. Scientific papers enumerating surgical disasters when this is employed is common place...

READ MORE