AAOS Bulletin - August, 2005

“Less invasive” hip replacement makes sense


    Thomas P. Sculco, MD

Over the past several decades, the trend among all surgical disciplines has been to perform surgical procedures through less invasive, less extensive approaches without compromising patient outcomes. The use of laparoscopic techniques has enabled major advances in abdominal, vascular, neurosurgical and gynecologic surgery.

A similar trend has evolved in orthopaedics, with increased utilization of arthroscopic surgery in all peripheral joints, and the use of less traumatic approaches for trauma and spinal surgery.

It is a logical extension of these improved surgical techniques that similar procedures would develop in the field of arthroplasty.

Eight years ago, an orthopaedic resident assisting me in a traditional 9- to10-inch posterolateral approach to the hip asked why I was using such a long incision when the lower half was not being used. I realized that he was correct—the incision was unnecessarily long. This realization led me to reduce both the skin incision and the deep dissection in ensuing cases. Instrumentation and angulated reamers were soon developed to allow hip replacement through smaller surgical windows, without undue trauma to the underlying tissues. A subsequent randomized trial of two incision lengths documented reduced blood loss and a trend toward faster short term recovery in the smaller incision.1

Since then, more than 2,000 hip arthroplasties have been performed using this approach, resulting in radiographic and clinical outcomes no different from conventional hip arthroplasty. Despite the paper by Woolson, et al,2 regarding the appearance of such incisions, in my experience patients are extremely pleased with the incision’s cosmetic appearance. It is important to remember that excessive traction on the skin incisions may lead to a less satisfactory scar. The incision should therefore be increased in those patients where undue tension is being applied to the skin edges.

Terminology adds to confusion

Considerable confusion exists regarding these procedures, which has led to misinformation and media exploitation and retarded the rational development of this area of arthroplasty surgery. I believe the problem originates with the terminology used to describe the procedures, particularly the phrase “minimally invasive surgery.” Hip replacement surgery is not “minimally invasive” by its very nature, but the surgical exposure can be “less invasive”—which is a more accurate way to describe these techniques.

Less invasive procedures are not just about the skin incision but the entire management of the deep soft tissues. A recent study by Ogonda and associates,3 describes a randomized trial utilizing two incision lengths. When the mini-incision was used in this study, however, the muscle, tendon and capsule exposure was not altered, as traditionally performed in the less invasive approaches. Therefore it is not surprising that the results were similar in the two groups.

In the modified posterolateral approach that I have described, the incision is 10 cm or less in length. Neither the quadratus femoris nor the tendon of the gluteus maximus is resected, and the abductor mechanism is not traumatized. The anterior capsule of the hip joint must be released and, in stiff hips, the origin of the rectus femoris may have to be released. Full visualization of the acetabulum must be achieved so that proper reaming and component positioning can be accomplished. Additionally, this approach exposes the entire proximal femur canal.

Seven lessons learned

I have learned several important lessons while using this modified approach.

1. This approach is not appropriate for every patient. More extensile approaches are necessary and must be performed in heavily-muscled patients—particularly males—and in significantly obese patients.

2. Proper instrumentation must be used, including long-handled retractors that facilitate exposure but do not impair the surgical site. Angulated reamers and acetabular cup inserters also reduce inferior soft tissue and skin injury.

3. To perform these procedures well, surgeons must be experienced in hip surgery. One must never compromise the surgical result with these approaches. I recommend using the standard approach and then reducing its extent in a gradual fashion until the surgeon is comfortable with his or her exposure and ability to perform successful arthroplasty.

4. Regional hypotensive anesthesia provides a surgical field with less bleeding, which makes the procedure significantly less complex.

5. A monoblock acetabular component eliminates the need for inserting a modular liner into an acetabular shell, which makes the procedure less problematic.

6. To avoid sciatic neuropraxia, do not use excessive posterior pressure on femoral exposure and extend the soft tissue release if necessary.

7. Surgeons who are interested in this approach should either consult a surgeon who has considerable experience using the techniques, or perform the procedures in a psychomotor laboratory prior to attempting it on patients.

Although these less invasive approaches may not be right for every surgeon, they have stimulated interest in reducing the extent of excessive, unnecessary techniques. Interest in the procedures has encouraged many surgeons to reevaluate how radical their surgical exposures need to be. Certainly a 3- to 4-inch incision need not be performed by every surgeon, but a 12-inch incision is not necessary in the overwhelming majority of patients.

The two-incision technique, as popularized by Berger,4 requires considerable training and presents an increased, documented risk of femoral fracture and implant malposition. In my opinion, this technique should be reserved for surgeons with particular interest in this area. I question its utility among orthopaedists who perform limited numbers of hip arthoplasties.

In summary, skepticism is healthy when new procedures are introduced. Modifications of accepted surgical techniques are often easier to learn and perform successfully, but above all, the surgical outcome must be optimal.

A significant shift toward less invasive approaches that are less traumatic to the patient has already taken place. As surgeons embark in this area, they must always keep in mind the Latin translation of Hippocrates’ sage counsel, “Primum non nocere”—first do no harm.

Thomas P. Sculco, MD, is surgeon-in-chief, director of orthopaedic surgery, and chief of the arthritis service at Hospital for Special Surgery in New York City.


1. Chimento GF, Pavone V, Sharrock N, Kahn B, Cahill J, Sculco TP: Minimally invasive total hip arthroplasty: A prospective randomized study. J Arthroplasty 2005 Feb;20(2):139-44.)

2. Woolson ST, Mow CS, Syquia JF, Lannin JV, Schurman DJ: Comparison of primary total hip replacements performed with a standard incision or a mini-incision. J Bone Joint Surg Am 2004 Jul;86-A(7):1353-8.

3. Ogonda L, Wilson R, Archbold P, et al: A minimal-incision technique in total hip arthroplasty does not improve early postoperative outcomes. A prospective, randomized, controlled trial. J Bone Joint Surg Am 2005 Apr;87(4):701-10.

4. Berger R: Minimally invasive THR using two incisions. Orthopedics 2004 Apr;27(4):382-3.


Small incision THR not “minimally invasive”

    Steven T. Woolson,MD

In 2001, two new techniques for total hip replacement (THR) surgery were introduced that use smaller incisions to accomplish the same procedure that is done through an incision longer than 15 cm. One technique uses one small (6 cm-10 cm) incision through a posterior, lateral or anterior approach. The second approach uses two very small incisions—a 2.5 cm posterior incision for placement of the femoral component and a 5 cm anterior incision for placement of the acetabular component.

These procedures have been termed “minimally invasive,” because it is claimed that they result in less soft tissue trauma, thus decreasing postoperative pain and blood loss, shortening the recovery time and reducing the hospital stay compared to the standard incision technique. However, these claims are based solely on the results of single surgeon patient cohorts that were compared to historical controls, rather than on studies that compare these new techniques to concurrent similar control groups.1-10

Until recently, there haven’t been any good studies comparing small and standard incision procedures, so it has not been proven these small incision THR procedures are actually minimally invasive. A question still remains as to whether a small skin incision procedure that requires high retractor forces on the soft tissues to expose the joint, but less muscle dissection, is less traumatic to the patient than a larger incision with wider muscle dissection, but with lower retraction forces.

It is also unknown whether the decreased ability to visualize the anatomy using these techniques is adequate to prevent a higher complication rate from damage to the surrounding neurovascular structures, or to produce a long-term result equivalent to a standard incision THR. If the limited visualization from small incisions is adequate, the results of small incision THR should show complication rates due to fracture, nerve palsy, infection and component malposition that are no higher than those incurred by a standard incision.

Comparing study outcomes

Three studies offer direct objective laboratory evidence that there is no difference in the extent of tissue damage between mini-incision and standard-incision techniques. Chimento and Sculco found no significant difference in the increase in surgical trauma (interleukin-6 levels) after THR between patients who had a mini- or standard posterior approach THR.11 McMinn found no significant difference in muscle damage (creatine kinase levels ) in patients who had mini versus standard incision surface replacement.12 Oganda et al found no difference in the postoperative inflammatory response (C-reactive protein levels) between randomized mini-incision and standard incision groups.13

Until 2005, there were no “gold standard” scientific comparison studies of small versus standard incision THR published in orthopaedic literature, despite the fact that surgeons and manufacturers had promoted these procedures for 4 years. Currently, there are five studies comparing small incisions to standard incision in which the comparison groups were similar in demographic parameters (age, weight, body mass index), three of which are randomized and prospective.4,11,13-15 All of these studies have found no statistical differences between small and standard incision THR with respect to clinical indicators of trauma such as postoperative narcotic requirements, pain scales and length of hospital stay. Two of these five studies did report lower average intraoperative blood losses of 43 cc and 67 cc in mini-incision patients, but they did not show a difference in the transfusion requirements between patient groups.11,15 One study showed a significantly lower transfusion rate (0.4 units) in the mini-incision group, but this difference was probably not clinically important.4 Two studies demonstrated less limp in mini-incision patients at 6 weeks to 6 months, but no difference at 1 year.4,11

Two other studies have shown evidence of more subcutaneous tissue necrosis and/or poor wound healing after mini-incision procedures.16,17 This would indicate that more soft tissue trauma is involved from the higher retraction forces needed for exposure in small incision procedures. A recent cadaver study of two-incision and mini-incision techniques indicates that significant abductor and external rotator muscle or tendon damage occurs with blind reaming (under fluoroscopy) of the femur and insertion of the prosthesis with the two-incision procedure, despite the contention by one of the innovators of the procedure that no muscle or tendon is cut during this operation.18 This same study also showed that more damage occurs to the gluteus medius and minimus muscles during mini-incision technique than advocates of the procedure have previously claimed.

Visualization of hip anatomy is definitely impaired when a small incision procedure is performed. This should result in longer surgical times, higher complication rates from fractures or nerve palsies, higher blood loss (from an impaired ability to achieve hemostasis) and more component malposition. All two-incision cohort publications report relatively long surgical times compared to open techniques, confirming the high degree of difficulty of the procedure. Although Berger reports a low risk of femoral fracture (1 percent) with the two-incision technique1, Mears, another innovator, reported a 2.8 percent fracture rate3 and other authors (non-innovators) have reported very high (7 percent to 9 percent) incidences of femoral fracture.19,20 A 4 percent early reoperation rate for treatment of postoperative fractures that were assumed to have occurred intraoperatively, but not detected by fluoroscopy or on the immediate postoperative radiographs, has been reported.19 Another study of two-incision patients has shown a 10 percent early reoperation rate for treatment of femoral fracture, dislocation or infection.21 In addition, a report of three cases of serious complications from both mini- and two-incision procedures requiring difficult revision surgery was recently published.22

Although three of the two-incision innovators had no occurrences in their first 300 patients, the risk of femoral and lateral femoral cutaneous nerve palsy is very high in studies by non-innovators.3 Bal reported a 25 percent incidence of lateral femoral cutaneous nerve (LFCN) palsy and a 1 percent femoral nerve injury rate in one two-incision cohort.21 Fick et al reported an even higher LFCN palsy rate of 39 percent.23 The high occurrence rate of nerve injury and fracture for the two-incision technique by Pagano et al of (2.5 percent), and from the Zimmer learning center (3.2 percent) indicate that this procedure is not safe enough to warrant its continued use on a non-investigational basis, especially when both of these studies could not identify a decrease in the prevalence of these serious complications with increased surgeon experience with the technique.19,20 The lack of a learning curve indicates that the two-incision procedure itself may be flawed, if surgeons could not reduce their complication rate with more practice.

Overcoming persuasive marketing

Marketing information presented to the public by surgeons and manufacturers through the Internet and consumer publications have claimed excellent results for small incision THR and have driven the popularization of the technique rather than peer-reviewed scientific evidence. However, surgeons who use the Internet for marketing purposes should be aware that the ethical use of advertising of medical practices according to the AMA Code of Medical Ethics requires that surgeons must not communicate misleading facts due to omission of necessary material information.24 The results of recent randomized, prospective studies showing no benefits to the patient from small incision THR procedures should be included in these Internet advertisements.

In conclusion, a review of the literature shows no convincing evidence at the present time of any significant advantages to the patient from small incision THR over standard THR, other than a smaller surgical scar. Because recent randomized prospective studies have shown no clinical differences, it is unlikely these small incision procedures are actually less invasive.

Patients considering these procedures should be told that there are few documented advantages and that there may be higher risks with small incision technique.25 The use of these procedures by low-volume joint replacement surgeons may be problematic because they are more difficult to perform, and legal liability for untoward outcomes, such as nerve palsy and leg length discrepancy, could be high. Comparison studies that prove both significant advantages and low complication rates for small incision THR are needed before either of these new procedures are recommended for general use by all surgeons.

Steven T. Woolson, MD, is a clinical professor at Stanford University Medical School.


    1. Berger RA: Total hip arthroplasty using the minimally invasive two-incision approach. Clin Orthop 417: 232-241, 2003.

    2. Berger RA, Jacobs JJ, Meneghini RM, et al: Rapid rehabilitation and recovery with minimally invasive total hip arthroplasty. Clin Orthop 429:239-247, 2004.

    3. Berry DJ, Berger RA, Callaghan JJ, et al: AOA Symposium: Minimally invasive total hip arthroplasty. J Bone Joint Surg. 85A:2235-2246, 2003.

    4. DiGioia AM, Plakseychuk AY, Levison TJ, et al: Mini-incision technique for total hip arthroplasty with navigation. J Arthroplasty 18: 123-128, 2003.

    5. Goldstein WM, Branson JJ, Berland KA, et al: Minimal-incision total hip arthroplasty. J Bone Joint Surg.; Supplement 4, 85A: 33, 2003.

    6. Howell JR, Masri BA, Duncan CP: Minimally invasive versus standard incision anterolateral hip replacement: a comparative study. Ortho clinics of NA 35:153-162, 2004.

    7. Kennon RE, Keggi JM, Wetmore RS, Zatorski LE, Huo MH, Keggi KJ: Total hip arthroplasty through a minimally invasive anterior surgical approach. J Bone Joint Surg.; Supplement 4; 85A: 39, 2003.

    8. Wenz JF, Gurkan I, Jibodh SR: Mini-incision total hip arthroplasty: a comparative assessment of perioperative outcomes. Orthopedics 25:1031, 2002.

    9. Wright JM, Crockett HC, Delgado S, et al: Mini-incision for total hip arthroplasty: a prospective, controlled investigation with 5-year follow-up. J Arthroplasty 19:538-545, 2004.

    10. Wright JM, Crockett HC, Sculco TP: Mini-incision for total hip arthroplasty. Orthopedics, Special Edition; 7:18-20, 2001.

    11. Chimento GF, Pavone V, Sharrock N, et al: Minimally invasive total hip arthroplasty: a prospective randomized study. J Arthroplasty 20:139-144, 2005.

    12. McMinn DJW, Daniel J, Pysent PB, et al: Mini incision resurfacing replacement of hip through posterior approach. Clin Orthop, in press, 2005.

    13. Ogonda L, Wilson R, Archbold P, et al: A minimal-incision technique in THA does not improve early postoperative outcomes: A prospective randomized controlled trial. J Bone Joint Surg 87A: 701-710, 2005.

    14. Wright JM, Rosse S, Rosse D, Lyman S: Comparison of abridged to standard incision total hip replacement: a prospective, randomized, blinded investigation. Proceedings of AAOS Annual Meeting, Washington, DC, February 2005.

    15. deBeer J, Petruccelli D, Zalzal P, et al: Single-incision, minimally invasive total hip arthroplasty: length doesn’t matter. J Arthroplasty 19:945, 2004.

    16. Woolson ST, Mow CS, Syquia JF, et al: Comparison of primary total hip replacements performed with a standard incision or a mini-incision. J Bone Joint Surg. 86A: 1353-1358, 2004.

    17. Goldstein WM, Ali R, Murphy SI, et al: Patient priorities and importance of cosmesis after THA: Standard versus minimal incision. Proceedings of AAOS Annual Meeting, Washington, D.C., 2005.

    18. Mardones RM, Nemanich JP, Trousdale RT, Pagano MW: Muscle damage after THA done with the 2-incision minimally invasive and mini-posterior techniques. Proceedings of AAOS Annual Meeting, Washington, D.C., 2005.

    19. Pagano MW, Leone J, Lewallen DG, Hanssen AD: Two-incision THA in 80 consecutive unselected patients: prevalence of complications. Proceedings of AAOS Annual Meeting, Washington, D.C., 2005

    20. Archibeck MJ, White RE Jr: Learning curve for the two-incision total hip replacement. Clin Orthop 429:232-238, 2004.

    21. Bal BS, Haltom JD: Complications associated with the two-incision technique in primary total hip arthroplasty. Proceedings of AAOS Annual Meeting, Washington, D.C., 2005

    22. Fehring TK, Mason JB: Catastrophic complications of minimally invasive hip surgery: a series of three cases. J Bone Joint Surg. 87A: 711-714, 2005.

    23. Fick DP, Haebich S, Nivbrant, Wood DJ, Khan R: Single versus dual incision minimally invasive hip arthroplasty. Poster exhibit, AAOS Annual Meeting, Washington, DC, 2005.

    24. Code of Medical Ethics, Chicago, Ill., American Medical Association, 1997.

    25. Lieberman JR: New technology and the orthopaedic surgeon: are you protecting your patients. Clin Orthop 429: 338-341, 2004.

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