Beyond Definitions to Approaches and Insights Four orthopedic surgeons share their opinions, concerns, and patient-specific techniques in a discussion of minimally invasive total hip arthroplasty. With the growing interest in minimally invasive total hip replacements, many surgeons have moved from seeking definition on what actually constitutes minimally invasive surgery to needing insight on how to begin the process of performing these procedures. Recently, a group of orthopedic specialists-experienced in several different minimally invasive approaches-gathered to discuss their procedures, as well as to provide insight into performing minimally invasive total hip arthroplasty (THA). DISCUSSION PARTICIPANTS The moderator of this discussion was John Keggi, MD, an orthopedic surgeon specializing in joint replacement at Waterbury Hospital, St Mary's Hospital, Connecticut Children's Medical Center, and Griffin Hospital, all in Connecticut. He is a clinical instructor at Yale School of Medicine. Other participants included: Roger Emerson, MD, an orthopedic surgeon on staff at Texas Center for Joint Replacement near Plano, Tex, is an Aufranc Fellow in Reconstructive Orthopedic Surgery at Tufts University, as well as an associate professor of orthopedics at the University of Texas Southwestern Medical School in Dallas. David Fisher, MD, director of the joint implant service at Methodist Hospital in Indianapolis, and president of Ortho Indy. Fisher is also an assistant clinical professor of orthopedic surgery at Indiana University. Kristaps J. Keggi, MD, director of the Joint Center at Waterbury Hospital, Waterbury, Conn, and a professor at Yale University. Keggi has been an advocate of minimally invasive surgery for more than 30 years, and has, with his associates at Waterbury Hospital, successfully used a minimally invasive anterior approach to total hip arthroplasty in more than 6,000 patients over a 30-year period. John Keggi, MD John Keggi, MD: Briefly describe what you are currently performing in the way of minimally invasive or less invasive total hip arthroplasty. Roger Emerson, MD: I use a small anterior lateral incision on older patients 10 to 12 cm. On younger active patients, I use a posterior mini approach, usually 8 to 10 cm. I have done several two-incision supine approaches under fluoroscopy, but as yet do not know how this approach will fit into my usual practice. Patients for a mini approach must be reasonably thin and not too large muscled. These mini approaches currently account for about 50% of my THA procedures. David Fisher, MD: I am currently using both a small incision anterolateral and posterior approach for total hip arthroplasty. I have performed a number of two-incision hip replacements and now only rarely consider this approach. I prefer the anterolateral approach when I use a 28 mm femoral head or in patients with a higher risk of dislocation. The posterior approach with capsular repair is preferred when I use a 36 mm metal on metal bearing. Kristaps J. Keggi, MD: I use an anterior approach, either single- or two-incision technique, which has been used for many years in our practice. The anterior approach or muscle-sparing approach has been used in our practice as a single incision technique since the early 70s and as a two-incision option since approximately 1986. The basic incision is 4 to 10 cm, and, if necessary, an accessory, proximal stab incision is made for reaming of the femur and component insertion. I usually make a second incision about 90% of the time. I occasionally make a third short stab incision distal to the main incision in the anterior thigh to introduce instruments and for acetabular reaming in large patients. John Keggi: What led you to start performing less invasive or minimally invasive hip arthroplasty? Emerson: It was crystal clear to me that if I were a patient I would want to have shorter hospitalization, quicker rehab, and less pain, with no higher risk of a complication. Surgeons who can accomplish this are going to be sought after and will be helping their patients. There may be disagreement about whether these claims are all true, but the concept of less invasive surgery has become the norm in other surgical fields and I suspect will become the norm in joint replacement in the future. Fisher: We started using smaller incisions for total hip replacement in January 2000 in response to public interest in minimally invasive surgeries. We basically just started using smaller incisions until we had reduced the incision from 8 to 4 inches. We also started looking at the two-incision technique at that time. Kristaps J. Keggi: I've been using minimally invasive total hip surgery since the mid 1970s. I have always felt that there was no point in making a long incision if you could do the operation with a short incision. A short incision reduces patient trauma and also reduces surgeon time to close the larger incision. I think if you are a busy surgeon and you do not have any assistants that you can rely on, it is helpful to try to minimize the incision. We are making minimally invasive, short incisions that split muscles rather than cut muscles. Minimally invasive surgery for total hip arthroplasty has reliably been shown to lead to smaller incisions, less blood loss, fewer complications, and faster patient recovery. While both minimally invasive and traditional incisions have the same end result at 1 year postprocedure, in the early phases of recovery I think people with a short incision and less muscle damage recover faster. John Keggi: In transitioning from a more traditional exposure to the small incision, what were some of the critical issues that have occurred? How did you solve these issues? Emerson: Even with less invasive surgery, the surgeon has to be in complete control of the surgical procedure and have adequate visualization to safely perform each step. The first key issue that I have come to appreciate is precise placement of the incision. This takes some thought, and if it is correctly placed, the rest of the case will go well. The next issue is that hard retraction and forceful twisting and pulling on the leg usually do not result in better visualization. The key is to learn how to gently manipulate the leg to put the femur or the acetabulum in just the right position for the task at hand. This means more moving of the leg throughout the case. The last issue for me was to realize that there was little benefit to heavy blows of the mallet, especially when your visualization is diminished. If a component does not fit properly with moderate tapping of the mallet, then I will do additional reaming and broaching. This will prevent a lot of fractures. Experience, asking colleagues, and observing other surgeons operating have been the means I have used to get by these issues. Learning a different operative style takes less time than you would think. I think it would be very difficult to learn less invasive surgery before having learned traditional open surgery. Fisher: There were several challenges to moving to a small incision technique. I agree that finding the correct placement for the incision was the first. In order to prepare and implant the cup and stem, the incision must be in the correct place. The second challenge was the size and placement of the retractors. Avoiding excessive skin and muscle damage can be accomplished only with appropriate use of the incision and retractors. While the basic approaches are not different from the more "open" procedures, there was definitely a learning curve in moving to the smaller incisions. While there were no infections or wound breakdowns, I'm certain there was more trauma to the wound edges in our early cases. This was mostly due to incorrect incision placement. As for exposure, we tried different combinations of retractors until we found a mix that allowed optimal exposure for the different approaches. Kristaps J. Keggi: It's a whole process because there is no such thing as deciding one day that you are going to go from a 10-inch incision to a three-inch incision. It is a process to make your incision shorter because, as surgeons transition to shorter incisions, they must be careful not to run into greater complications such as: over-reaming the acetabulum, reaming into the pelvis, perforating the femur, or breaking the femur. All of these complications can be a result of not having adequate visualization or because a surgeon is doing an operation through a too small incision. You must end up with a hip in the proper position without fractures, perforations, or damage, or excessive bleeding. If you can achieve good hip placements through a short incision with minimal muscle damage, then you are doing great work. If these complications occur, surgeons are better off doing a larger visualization, larger exposure, and have a patient that takes a few weeks or a couple of months longer to recover but doesn't recover with any major catastrophes. John Keggi adds: In the anterior approach, the challenge can be in the preparation of the femur. In single incision anterior cases, the femur must be mobilized anteriorly in the wound to allow for broaching and insertion. This is accomplished with a posterior capsulotomy through the anterior wound. This works well but can be associated with bleeding if the capsular incision extends more medially or more inferiorly (or with venous normal variants). The second incision obviates the posterior capsulotomy and allows preparation of the femur and insertion of cemented or noncemented components. Another issue is alternative anterior incisions. Initially, a curvilinear incision was used that has evolved into a diagonal incision along a line drawn between a point 1 to 2 cm distal to the ASIS to the anterior border of the greater trochanter. I find it best to make the incision along this line perhaps 2 to 3 cm lateral from the most medial point. In a thin patient the incision can be 5 to 6 cm. Fluoroscopy is not used. The tensor is split just lateral to its medial border. The capsule can then be excised. The proximal stab incision is made to use the interval behind the tensor and anterior to the abductors. We have investigated this in cadaveric dissections and clinically. In some large patients, the interval ends up being through the distal aspect of the abductor tendon distal to the gluteal nerve ramifications. John Keggi: Which traditional methods of retraction are still adequate for the small incision? What methods of retraction do you use? Fisher: A self-retaining retractor and smaller retractors can be used. I also find the intrapelvic retractor quite useful in these cases. There are newer retractors that have been designed for small incision surgery that may have more utility. The key to use of retractors is to position them in a manner to allow exposure to the acetabulum or femoral canal, and protect the soft tissues during instrumentation and prosthesis insertion. I frequently use a unique self-retaining retractor that allows one to perform total hip arthroplasty with minimal assistance. The system provides a self-retaining retractor that is further secured to the operating table. This helps maintain patient position during the procedure in a hands-free manner, securing the patient and aiding in proper implant positioning. Furthermore, deep retractors can be placed and secured to the self-retaining retractor providing superficial and deep exposure without the need for a surgical assistant. Roger Emerson, MD Emerson: In my experience, the assistant will have his or her hands full just suctioning, boveying, and manipulating the leg. Holding a retractor, in addition, would be a real chore. Small incisions do not just fall open like some long revision incisions will. Some type of self-retaining retractor is going to be necessary; I also use a table-mounted hip retractor system, which is crucial for the more demanding hip surgeries like the mini-invasive hips-and also the revisions-especially when there is variability in number and retractor proficiency of OR staff. The retractor stays where I put it, but is nonetheless quite adjustable. The retractor's toe-in feature works well to create a direct tunnel down onto the operative site and relieves pressure on the skin (hard to get the human with handheld retraction to do this as well). My concern with many of the other retractors is that they can be quite damaging to the skin and in my experience are difficult to keep in position. I still supplement my table-mounted retractor with some handheld retractors from time to time. I have a long narrow right-angle retractor that can be helpful. Kristaps J. Keggi: While it is possible to do an effective total hip replacement with a very small amount of instruments, if adding a special retractor makes the operation less bloody and allows you to visualize the femur and acetabulum better, then you really owe it to your patient to utilize those tools. The main advantage of the newer instrumentation has to do with the visualization of the acetabulum, less blood, and also standardization of operations. In other words, you make the incision here, you put the retractors in here, you leave them there, you move them around a little bit if necessary, and have a better procedure as a result. You have a better chance of putting the components in the proper position by using a table-mounted retractor. The biggest thing about the retractor that I use is its ability to free up assistants to some extent. Instead of hanging onto a retractor, the assistant can now adjust the lights, suction blood, or participate in other ways. The instruments themselves stabilize the field; once the retractors are properly placed, they are fixed. It's not like a resident who is holding a retractor and moves one way or another, and the retractor slips and has to be repositioned, and muscles bulge over the sliding retractor. Once the fixed blades on this retractor are in place, they stay positioned and help stabilize the operative field. I'm also convinced, although it is hard to quantify, that this system minimizes the bleeding, especially during the operation. You are really working in, from the anterior approach, an almost bloodless field. It retracts the major vessels and compresses the smaller vessels and the muscles that might bleed. John Keggi: Many orthopedic surgeons talk about the need for a "moving window" wound during minimally invasive hip procedures. How do you employ a moving window technique? Fisher: The "moving window" refers to the fact that an incision can be retracted in one direction or another, giving access to various deep structures such as the acetabulum or the femoral canal. Placed in the proper position, such a "mobile window" will allow access for instrumentation and implant insertion without undue skin or soft tissue damage. With slight adjustments of the table-mounted system, a small hip incision can be mobilized to gain access to either the acetabulum or the femoral canal. With the small incision, it is definitely a plus to have fewer hands in or around the wound. Emerson: There is no doubt that the small incision needs to move around some to permit access for the procedure, but I have found that a better technique is to get the incision in the right place to start off with, and then manipulate the leg to put the femur or acetabulum into view. Again, I am not much of a wound shifter. For preparation of the femur, which requires the most manipulation of the leg, I will frequently use the retractor system's "hooks" to hold the tissues apart, rather than the blades. The blades work best for the acetabulum. John Keggi: Surgeons are seeing a growing number of obese patients in their practices. I have found that size is not a contraindication as I have used the two-incision technique in patients up to 400 pounds. However, exposure is more of a concern with these patients. Are there any instruments that help reduce the difficulty of visualizing during surgery on very large patients? Emerson: I have performed THA on a number of obese patients that I feel I could not have done less invasively without the retraction provided by the self-retaining retractor. If there is one situation where this device is most helpful, it is in the obese patient. I also use a headlight for these patients and have some extra-long kockers and curettes available. I did not use a headlight with open surgeries, but have had a headlight fitted to my helmet, which fits inside the face screen for use in minimally invasive THA procedures. There is a little reflection back, but not enough to be a problem. David Fisher, MD Fisher: Obesity is a major health care challenge for our society. With the demographics of the Midwest, I see a large number of obese patients. I don't even discuss minimally invasive surgery with them because exposure and implant placement are far more important than the size of the incision in an obese patient. Now having said that, I do use a smaller incision than I used to on these patients. And, once again, incision placement is even more critical in this group. Deeper self-retaining retractors are needed. I use heavy-duty retractors, but if the incision is in the correct place, the procedure can go smoothly. One of the challenges in the obese patient is keeping the pelvis stable and obtaining correct cup position. This is a struggle for most hip surgeons, and for this reason, I prefer the anterolateral approach in my obese patients. Kristaps J. Keggi: On larger patients, I absolutely think just retracting the tissue is a huge task. It's not the kind of thing that is accomplished by an OR staff person holding onto the end of a retractor, opposite where you are standing as a surgeon. In most situations, having instrumentation that makes the process easier certainly makes sense. The fixed retractors that we've been using have really been very helpful, especially in the larger heavier patients, even with resident assistance available. The table-mounted systems are better because they provide more consistency in the retraction versus handheld retraction. Regardless of patient size, one of the advantages in having a fixed retractor is that you are not constantly exchanging position. John Keggi: How would you advise a colleague on how to begin performing less invasive total hip arthroplasty procedures? Emerson: I would advise a colleague to gradually shrink the incision down and do not hesitate to lengthen an incision if necessary. Sometimes, even one to two more centimeters can make all the difference. The next advice would be to get the proper tools to do less invasive surgery. I strongly believe that tools intended for this type of surgery will allow more consistent implant positioning and safer surgery. You can start diminishing the incision with standard instruments, but need the specialty instruments to go to the next level. Fisher: I agree with Dr Emerson to move toward smaller incisions gradually. Surgeons will find that exposure adequate for instrumentation and implant insertion can be obtained with a well-placed small incision. The more basic question is can we obtain the same quality of arthroplasty with a small incision compared to the traditional approach. I'm not sure we have enough data to convince me that this is the way all total hip replacements should be performed. Kristaps J. Keggi, MD Kristaps J. Keggi: There has to be a commitment to go through the entire learning process. The first thing a surgeon must do is commit and say yes, I'm convinced that, for example, minimally invasive THA patients do better in the short run. It's not the kind of thing that you can say I'm going to do it and then have it happen with the next two or three patients. You may have to watch another surgeon operate, operate on several cadavers in anatomy lab, or view procedure videos and DVDs that have been produced. After you are committed to learning minimally invasive THA, start the operation with an incision large enough for comfort for your particular skill level as a surgeon. Then, instead of making a two- to three-inch incision, make a four-inch incision. Make an incision that is slightly longer and work your way into the hip, see where you are, and what the problems are. Do a few cases through these larger incisions and convince yourself that it's possible to do it through an anterior approach or through a two-incision approach and then gradually make shorter and shorter incisions. You have to be committed to the whole process of learning and using the instruments, thinking about it, seeing somebody else do it, and then proceed gradually. John Keggi: What changes have you recently made that have improved your technique? Emerson: All of us are continually learning how to do surgery better everyday. My latest addition was the headlight for completing THA procedures on obese patients. I used to set up the retractor when I needed it, but now put it together at the start of the case, and swing it into position when needed. This leads to less interruption of the flow of the surgery. Fisher: I think that the techniques will continue to evolve. Recent innovations in instrumentation for bone preparation and implant insertion make small incision surgery easier. Devices such as curved reamers and cup inserters make cup insertion through the posterior approach a little easier. Improved retractor systems will cause less soft tissue damage. The use of computer navigation will probably lead to more accurate placement of our implants but may not see widespread use for some time. Improved methods of pain management and rehabilitation may reduce recovery times and decrease hospital stay. Many of my younger patients are now discharged within 24 hours, weight bearing as tolerated. Multimodal pain management with nonsteroidal anti-inflammatory drugs, soft tissue injections at surgery, and narcotic analgesics all seem to have a place in perioperative pain management. When coupled with aggressive rehabilitation protocols, a faster recovery can definitely be seen. Kristaps J. Keggi: I'm doing many less posterior releases. I don't mobilize the femur as much as I used to during my first 25 years of total hip surgery. Modular hip implants are an effort to standardize what we are doing, and it's the sort of change I have arrived at gradually as part of the whole process, not something that's happened overnight. It's performing a total hip from the front in 1973, and then making the incision shorter, presenting it to the Academy, discussing it, teaching it to residents, thinking about modifications, making reduced size acetabulum reamers in the early 80s, converting standard acetabulum reamers to retrograde acetabulum reamers, and now to modular hips. We've been working on minimally invasive THA procedures for 30 years, so I've gone through a learning process as well. John Keggi: What new, specific pre- and post-operative requirements are necessary to communicate to the anesthesiologist and hospital staff? Emerson: If you are sending patients home in the first 24 hours, then your anesthesiologist needs to be aware of this. I like epidural techniques, but this means that I cannot administer low molecular weight heparins or other similar anticoagulants until after the catheter has been removed. I like to inject local anesthetics with epinephrine in the incision, and always give the anesthesiologist a heads up when I inject. Fisher: I find it helpful to have an anesthesiologist skilled in regional anesthesia. We use a lot of spinal blocks with intrathecal narcotics in our patients older than 55 years of age. Our anesthesia department generally is very good at providing intraoperative hypotension. This facilitates visualization when using a small incision. In addition, the blood loss has been less with the minimally invasive procedures, as well as shorter operating time. The OR staff need to be very familiar with the procedure and what the surgeon is trying to do. With small incision surgery, the surgeon is often the only person who can really see in the depths of the wound. The assistants can only hold the retractors where he places them and cannot see enough to know how to help. In the hospital ward, nurses and therapists need to know what surgical approach was used and how it will affect the patient's rehabilitation. We like to get the patient out of bed as soon as possible, and all parties need to know how to do that safely. Furthermore, we encourage the patient to actively engage in their rehabilitation and start doing exercises as soon as possible. John Keggi: What parts of the procedure still need to evolve in order to perform this procedure on the majority of patients? What comments have you heard from other surgeons that have kept them from performing this procedure on the majority of their patients? Fisher: Exposure and visualization remain the biggest challenges, and the difficulty varies with body weight. Better means of exposure and bone preparation will be needed to make minimally invasive hip procedures easier in the obese patient. The majority of total hip replacements are performed by surgeons who perform less than 50 procedures a year. That means they spend much more time doing other orthopedic procedures. The real challenge for them is to find the time to stay current with new developments, and try to incorporate them into their practice. There is a learning curve in learning these new techniques, and most surgeons will go slow until there is compelling data to convince them to change. Emerson: I am not sure that this less invasive surgery will ever be appropriate on all patients. Computer guidance techniques hold some promise as a means of consistently placing our implants with less visualization. This has yet to be proved to my satisfaction. The increased technical difficulty and longer surgical time are the two issues that I hear presented. These can be dealt with by improved instruments and techniques, as well as with more experience. Kristaps J. Keggi: I do it in all THA patients. Every total hip I do is done the same way. It doesn't make a difference if the patient is 350 pounds or 110 pounds. It's always the same approach. It's a longer incision for the 350-pound patient and a shorter incision for the 110-pound patient. But the placement of the incision, the splitting of the muscles, the second incision, the first incision, everything is approximately the same. Bigger patients and more muscular patients have longer incisions, but it's always the same approach, a standardized way of doing it. The recovery in the thin patient with less trauma is faster, and in the larger patient, a little slower. We try to preserve muscles, we try to spare muscles, we call it the muscle spring approach in some cases, and recovery depends on the tissue damage that is created. The other thing that I do, which a lot of people don't do and I feel very strongly about, is excising of the anterior capsule, an important aspect. Trying to repair a contracted anterior capsule does not make sense to me. Excising the anterior capsule is an important aspect of performing this procedure, because the anterior capsule is tight and hinders exposure. If it is left intact, is repaired, or is contracted, it acts as sort of a tether. The anterior capsule promotes dislocation postoperatively if it's not been excised, especially coming from the posterior approach and you can't reach it. With the anterior approach that we use from the front, the size of the incision and excising the capsule are important aspects of the procedure's overall success. This roundtable was compiled from a discussion that took place on October 5, 2004, at Waterbury Hospital, Waterbury, Conn. It was sponsored by a manufacturer of surgical retractors.