To The Editor:

Dr. Woolson raises important points concerning the two incision technique.

All patients upon whom this procedure was performed were informed that that procedure was new to our practice, and that we could not predict the outcomes. The procedure had been marketed in the consumer press, such that nearly all patients were already familiar with it. Patients were keen to have their hip replaced with this technique. The company did not help us market this technique, and the company was not involved in our decision to switch the femoral stem to a different design.

The 51% incidence of complications reflects an aggressive reporting of all possible complications with this technique. For example, in the reported incidence of lateral femoral cutaneous palsy, we captured all patients who had any lateral thigh numbness, however transient. The incidence of lateral thigh numbness included those patients who had any subjective feelings of altered thigh sensation, even in the absence of objective findings on sensory exam. Also included were a number of patients who had normal thigh sensation after surgery, but developed thigh numbness as the scar healed, presumably from branches of the lateral femoral cutaneous nerve incarcerated in the healing scar. Technique modifications can minimize the incidence of thigh numbness, but the patient should be aware that this problem can manifest with anterior incisions around the hip.

The switch to a ML taper stem was made because the surgeon had previous familiarity with this design, which has had excellent long-term outcomes cited in the article. This type of stem is simple to implant, and has fewer variables related to implantation and successful performance. The type of stem advocated for the two-incision technique in training seminars, and by the pioneer surgeons requires reaming of the femoral canal using intraoperative fluoroscopy.

With experience, our impression was that the complications with the two-incision technique can be avoided. That is why we continued to use the technique. The patients who did well with this method were so pleased with the outcomes that they marketed the technique to others seeking total hip replacement surgery. To ensure safety, the surgeon must visualize the acetabulum and the proximal femur satisfactorily when preparing bone, and when positioning implants. This is true of hip replacements regardless of surgical approach, and incision length. Reliance upon x-rays can be misleading. Implants that may appear properly positioned and size on fluoroscopic views can present a different picture on the postoperative radiographs.

At present, our approach for all primary total hip replacements is similar to that previously published by Keggi, et al,(1) using the Smith- Peterson approach. Patients show an improvement in early recovery parameters, as may be true of other minimally invasive total hip replacement techniques.

We agree that two-incision hip replacement surgery has been associated with a higher incidence of complications in several reports, while others have reported excellent outcomes. Other minimally invasive joint replacement techniques have also been associated with an increased risk of complications. With the two-incision technique specifically, the surgical approach is unfamiliar to most surgeons, and visualization is very limited. In our opinion, a training seminary is inadequate preparation for the technique. The surgeon must first gain familiarity with the Smith-Petersen approach to the hip. Also, the surgeon should be experienced in blind nailing of the femur. Adequate cadaver training and mentorship with an experienced surgeon are necessary to prepare for this technique. We recognize that such resources may not be readily available to all surgeons.

Reference:

(1) Kennon RE. Keggi JM. Wetmore RS. Zatorski LE. Huo MH. Keggi KJ. Total hip arthroplasty through a minimally invasive anterior surgical approach. [Journal Article] Journal of Bone & Joint Surgery - American Volume. 85-A Suppl 4:39-48, 2003

To The Editor,

I would like to applaud the authors of the paper “Early complications of primary total hip replacement performed with a two-incision minimally invasive technique”(1) for having the courage to share their experiences. This article added to the mounting volume of data indicating that so-called “minimally invasive” hip replacement procedures are not beneficial to the patient in any meaningful way and that these procedures have higher rates of complications and component malpositioning. The fact that the authors found no significant clinical benefits to this procedure is important and should be emphasized more than was done in the text, since their findings provide evidence that these procedures are probably just as invasive as standard-incision procedures, although not as safe. The authors found that using a two-incision technique the blood loss and surgical times were higher, and the the length of hospital stay was only 0.6 days less (13%) than for a group of patients who had a mini single incision THR. I am concerned, however, that the authors found no statistically significant difference in the mean surgical times between the procedures, despite a 35% increase in the surgical time for the 2-incision procedure patients.

The overall major complication rate of 42% (or 17%, if the lateral femoral cutaneous nerve injuries were considered minor complications) was extremely high. In the hands of a fellowship- trained total joint surgeon who limits his practice to joint replacement this rate should be less than 10%. The prevalence of femoral fracture (8%), early reoperation (10%), acetabular positioning outliers (28%) and poor fit of a cementless femoral component (10%) are alarming in the hands of a joint specialist and point to the fact that poor visualization of the anatomy rather than surgical expertise as the causative factor. The fact that there was no decrease in the risk of injury to the lateral femoral cutaneous nerve despite more experience with the procedure indicates that the surgical approach is flawed. The authors have shown that this procedure is unsafe and that when the complication rate for this new procedure is considered in the face of no apparent benefits to the patient (considering that there are no published comparison studies showing a benefit from the two- incision hip replacement procedure over standard incision hip replacement in the orthopaedic literature to date), it should not be recommended for use. This procedure should be considered experimental until randomized prospective comparison studies are available.

There are ethical issues brought up by this study. Since these patients were not enrolled in a prospective study with IRB approval and oversight, it is important to know whether the initial patients in this series were informed of the lack of prior comparison studies demonstrating efficacy and safety of the technique. Did the forty- nine patients done at the end of this study know what the complication rate was for the initial forty patients? It is unlikely that an IRB panel would have allowed this study to continue after a 51% complication rate in the initial forty patients was found.

There is also a question of why different implants from different manufacturers were used for the two study groups, even though the authors state that these were similar or essentially identical prostheses. After training at a Zimmer seminar on the two-incision procedure and beginning to use this new technique, the senior author apparently switched from his initial choice of hip implant to Zimmer implants. Was this switch the result of a clinical decision based on implant results or were there non-clinical reasons for this change? Did marketing assistance to the surgeon by the manufacturer that was supporting the use of this procedure affect the surgeon’s choice of hip implant?

There has been considerable discussion regarding the ethics of marketing over the Internet by companies and surgeons of unproven surgical techniques, most notably minimally invasive joint replacement techniques. The promotion of these techniques by manufacturers without scientific comparison studies showing both efficacy and safety is unethical and misleading to the public.

This study adds to the growing body of scientific data showing that that small-incision total hip procedures may be unsafe. Internet marketing information for these procedures must include this data so that patients who use the Internet for surgeon and procedure selection have informed consent.

Sincerely,

Steven T. Woolson, M.D.

Clinical Professor

Stanford University School of Medicine

Reference

1. B. Sonny Bal, Doug Haltom, Thomas Aleto, and Matthew Barrett Early Complications of Primary Total Hip Replacement Performed with a Two-Incision Minimally Invasive Technique J Bone Joint Surg Am 2005; 87: 2432-2438