December 2003 Bulletin

Skeptical perspectives on minimally invasive total hip arthroplasty


Point of View John J. Callaghan, MD
Total hip replacement has been performed in the United States for over three decades and in Europe for more than four decades. It is one of the most, if not the most, studied surgical procedure ever in medicine. Its efficacy in relieving the pain and functional limitations from end-stage arthritis of the hip has been documented.

During this 30- to 40-year experience, investigators and surgeons have documented some of the complications and shortcomings of the procedure as well as some of the potential innovations, which through the test of time have ended up being “steps backwards.” The potential benefits of the minimally invasive approach (i.e., the cosmetic appearance, quicker functional return, short length of stay, and fewer transfusions) have been outlined. If these goals can be accomplished while still addressing the major issues that confront orthopaedic surgeons who perform total hip replacement today, there may be a place for this enthusiasm. However, as described below, there are several reasons for skepticism as well as for concern about the approaches that have been implemented to encourage the widespread use of the minimally invasive approach.

What is the major problem with total hip arthroplasty today? From both an economic perspective, as well as from the perspective of the patient requiring a total hip arthroplasty, the need for additional surgery following the index procedure is of paramount concern. The revision rate in the United States is 18 percent to 20 percent, and unfortunately it is twice that of some other countries such as Sweden, where the rate is 8 percent. More data are arising to suggest that the volume of surgery performed at an institution, as well as the volume of surgery performed by an individual surgeon, is a major factor contributing to the revision rate. However, the practical reality is that more, not less, total hip replacements will be indicated in the aging and active population, as data have suggested that people will be living longer (and hence have an increased risk for the development of disabling hip arthritis) and the so-called baby-boomer generation is reaching the peak age for the onset of disabling hip arthritis.

These replacements cannot all be done at centers that do more than 500 or 1000 hip replacements a year. There will still be a huge need for surgeons who perform fewer than 50 hip replacements a year. Arthroplasties need to be performed with the fewest complications and with the least possible need for revision, because both are costly to the patient and to society. In addition, the increase in the rate of obesity in this country may prohibit more and more patients with disabling hip arthritis from being optimal candidates for a so-called minimally invasive procedure. Some proponents of the procedure recommend that minimally invasive techniques be performed in patients with a body-mass index of less than 30.

What are the major complications following total hip replacement that require revision? Failure of fixation, instability, and infection have been documented as the major causes of reoperation following total hip replacement. To minimize failure of fixation, implant-bone interfaces must be optimally prepared. To minimize dislocation, components need to be positioned optimally, osseous impingement (including osteophytes) should be eliminated, and stability needs to be assessed. To minimize infection, tissue trauma needs to be minimized, as does the duration of the operation. Small incisions do not address these problems, and they could potentially increase each of them, especially in the hands of a surgeon who is less skilled or who is doing fewer procedures. Some enthusiasts of the minimally invasive procedure assert that combining minimally invasive procedures with computer-assisted surgery will allow the computer images to overcome the lack of visualization allowed by the incision to optimize the position of the components. This presents a tremendous risk for very little, if any, proven benefit.

Is the comparison of minimally invasive hip surgery with the conversion from knee arthrotomy to knee arthroscopy accurate? There are reasons why this argument may not hold. The short- and long-term results of knee arthrotomy, unlike those of total hip replacement, were not optimal. In addition, it has been documented that visualization is actually better with arthroscopy. This claim has not and cannot be made for minimally invasive hip surgery.

Minimally invasive hip surgery may turn out to be more akin to the endoscopic carpal tunnel release than to knee arthroscopy. Endoscopic carpal tunnel release was touted for its ability to provide a smaller scar and early return to work. The subsequent peer-reviewed publications demonstrated no long-term benefit. Today, questions have arisen as to whether the potential early return to work after the procedure was mostly perceptual (the surgeon’s enthusiasm for the procedure and the patient’s desire to please the surgeon). The major complications of carpal tunnel release, including nerve laceration and tendon injury, still occurred after experience was gained with the procedure. For these reasons, endoscopic carpal tunnel release, which initially gained enthusiasm and popularity, has been abandoned by the majority of hand surgeons. This skeptic questions whether the results achieved by a traditional joint replacement surgeon who selects the most motivated and fit patients, convinces those patients of the possibility of early discharge, and performs the standard incision with optimal preoperative, intraoperative, and postoperative anesthesia, pain management, and rehabilitation would not match the early results or exceed the long-term results achieved by the surgeon who uses the minimally invasive approach.

Are there medical-legal liability issues associated with implementing the minimally invasive hip replacement approach? The argument has been stated that, because the patient has come to the surgeon desiring the technique, he or she must understand that there is a learning curve that could involve the potential for complications, such as nerve palsy and component malposition. Legally, the surgeon should recognize that he or she probably will be judged by the same standards as the surgeon who uses conventional incisions. In addition, complications may not be as well understood by patients with extremely high expectations of the surgery.

Has the minimally invasive hip surgery movement been appropriately implemented? The Internet and advertisements have encouraged patients to seek new treatments before traditional peer review can be completed. This creates potential problems for both the surgeon and the patient. There are many examples of self-aggrandizing promotions of unique treatments outside the peer-reviewed system that have not held up in the scientific review process or have not withstood the test of time. Our medical profession has been designed for us to self-regulate. We have an obligation to educate the public and help them to interpret nonscientific premises and promotions. Developers of groundbreaking treatments for patient care are obligated to promote their ideas through the scientific peer review of their data, which can substantiate their enthusiasm. In the case of the minimally invasive approach to hip surgery, the promoters have rarely recognized the work of Keggi, as reported by Light in 1980, who described a similar minimally invasive approach for performing total hip replacement. Finally, if a treatment does prove to be an improvement, it should not be limited to a select group of surgeons. These premises are the basis for the respect that the public holds for the medical profession today.

It is the job of a skeptic to ask tough questions. This skeptic hopes that minimally invasive hip surgery enthusiasts prove him wrong for this skeptical stance.

John J. Callaghan, MD is a member of the AAOS Council on Education and professor in the departments of orthopaedic surgery and biomechanical engineering at the University of Iowa College of Medicine. He can be reached at johncallaghan@uiowa.edu.

Reprinted with permission of The Journal of Bone and Joint Surgery, Inc. This article originally appeared in J Bone Joint Surg Am 2003;85:2242-43


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