New trends in ACL reconstruction

ACL reconstruction continues to be the most common, serious and controversial injury in orthopaedic sports medicine. There seems to be a slow shift in choice of graft, as hamstring tendons are now used at least as often as patellar tendon as an ACL graft because there appears to be less morbidity and improved fixation techniques with hamstring graft use. No clear scientific data exists that clarifies whether one graft is superior to the other. Discussion continues about graft tensioning and some rehabilitation techniques.

Most surgeons experience some residual pivot shift laxity after ACL surgery. Some recent biomechanical studies indicate that moving the femoral tunnel further down and/or using a two-tunnel technique in the femur may eliminate or at least decrease the residual pivot shift glide.

This virtual round table explores why orthopaedic sports medicine surgeons in different parts of the world currently choose their ACL graft and if they use the two-tunnel technique. Questions were distributed to the round table participants, who provided their responses via e-mail. We hope this debate will stimulate readers to look at their own surgical technique and how they solve the problem of residual pivot shift laxity.

Per Renström, MD, PhD
Moderator

MODERATOR Per Renström, MD, PhD Head, Section of Sports Medicine, Department of Surgical Sciences, Karolinska Institutet, Stockholm; member of the Orthopaedics Today Editorial Advisory Board PARTICIPANTS Paolo Aglietti, MD, Director, First Orthopaedic Clinic, University of Florence, Italy; member of the Orthopaedics Today Editorial Advisory Board Robert J. Johnson, MD, Head, Division of Sports Medicine, University of Vermont College of Medicine, Burlington, U.S.A. Ramon Cugat, MD, Orthopaedic surgeon, Clínica del Pilar; Head of Surgical Team, Catalan Football Federation, Barcelona; member of the Orthopaedics Today Editorial Advisory Board Hans H. Paessler, MD, Head, Center for Knee and Foot Surgery and Sport Traumatology, ATOS Klinik, Heidelberg, Germany Kazunori Yasuda, MD, PhD, Professor and Chairman, Department of Sports Medicine and Joint Reconstruction Surgery, Hokkaido University School of Medicine, Sapporo, Japan

Per Renström, MD, PhD: In your opinion, what is the “best” graft to use in ACL reconstruction?

Kazunori Yasuda, MD, PhD: At the present time, I consider that both the patellar tendon bone-patellar-bone autograft and the hamstring tendon autograft are the best grafts. In the future ACL reconstruction, however, the hamstring tendon graft has potential to be the best because it has less graft site morbidity and may be more suitable to the double-bundle technique.

Robert J. Johnson, MD: I don’t think there is such a thing as a “best graft.” There are no randomized clinical trials that prove that patellar tendon grafts are better than hamstring grafts, or vice versa. There are maybe 10 or 12 randomized clinical trials that do not show a clear indication that one graft or method is better than the other.

Paolo Aglietti, MD: I think that graft material properties of patellar tendon and hamstrings are comparable, and nowadays what makes the difference is the surgical technique and the fixation. We recently performed a prospective, randomized study comparing patellar tendon and hamstrings, and we found no differences in terms of stability and patients’ satisfaction.

Ramon Cugat, MD: I think bone-patellar tendon-bone (BPTB) grafts are best. I use these grafts in approximately 93% of my cases, with hamstring grafts in the other 7%. This is because the femoral tibial anchorages are better than those used for the hamstring tendon graft.

This image shows the surgeon placing a Kirschner wire through a patient’s tibia and femur and pulling a thread to test the isometry. The knee is flexed, which maintains a tight thread from the tibia to the femur. COURTESY OF RAMON CUGAT

Hans H. Paessler, MD: Our first choice for ACL reconstruction is the semitendinosus/gracilis (ST/G) or hamstring graft. We use this graft in an ACL reconstruction technique that we developed, utilizing press-fit fixation without any hardware.

Remarkable advantages of the ST/G graft are mainly less donor site morbidity and easy and rapid harvesting through a small (ie, 2 cm to 3 cm) horizontal incision. There is less risk of sensory nerve injury and better cosmetics using this approach.

We do not use BPTB grafts any more because we found there is too high a rate of donor site morbidity. We demonstrated that in a recent retrospective study, which will be published in the American Journal of Sports Medicine later this year.

In a recent study by Andreas Weiler and colleagues, they demonstrated that in a patient series using conventional bone-patellar tendon-bone and anatomic hamstring tendon graft ACL reconstruction, hamstring tendon grafts were superior in terms of knee stability and function. These findings are at least partially contrary to previous studies and might be attributed to the fact that an anatomic joint line fixation of hamstring grafts was used. Weiler and colleagues confirmed the results of the only existing long-term study, which was carried out by Pinzewski and colleagues, who compared hamstrings with BPTB — both with the same anatomic fixation — at seven years follow-up.

Our second graft choice is the quadriceps tendon, either with a bone plug or as a free tendon graft, which provides a very useful option for primary ACL reconstruction and ACL revision surgery. Use of this graft is associated with much less donor site morbidity than BPTB. The graft has a large cross-sectional area and its stiffness is closer to that of the human ACL than any other graft.

Renström: Do you prefer a single-incision or double-incision arthroscopic approach?

Johnson: I think the two-incision approach makes it possible, with much less technical difficulty, to get the tunnels for the grafts in the correct position. In my opinion, most single-incision or anterior approaches of endoscopic ACL reconstruction lead to slightly anterior and too often superior positioning of the graft, as one looks at the notch with the knee flexed at 90º.

Yasuda: I consider the one-incision/transtibial tunnel technique for the femoral tunnel better than the two-incision technique with a rear entry guide for the femoral tunnel. I think the one-incision approach is easier for trained orthopaedic surgeons in arthroscopy-assisted ACL reconstruction. The operation time is shorter, the surgery is less invasive for patients (ie, no surgical invasion of the thigh), and the procedure is better from the viewpoint of cosmetic surgery, which is particularly important for women in Japan.

Aglietti: In recent years I have performed the transtibial approach. I am happy with the results even if I don’t dislike the outside-in technique, which allows you to go lower in the notch and with a more horizontal tunnel.

Renström: Do you use double tunnels in the femur in your ACL surgery, and, if so, what are your indications?

Aglietti: I started the double-bundle technique almost a year and a half ago on the basis of the residual shift pivot glide, which I observed in almost one-fifth of the patients in my last series, and on the basis of biomechanical studies by Woo and by Muneta, who are in favor of a more anatomical reconstruction. I have not yet found a definitive surgical technique.

Most of my cases have been reconstructed using a transtibial approach for both femoral tunnels, but I am looking for a more precise femoral positioning. Until recently, I used the endobutton for fixation on the femur. The technique is obviously more demanding and difficult, and you have twice the possibility of making a mistake.

Johnson: No, I don’t use double tunnels. At this time there is no published proof in randomized clinical trials that indicates that one method is superior to the other. There are several biomechanical studies that indicate that the two-tunnel technique has advantages. However, the two randomized clinical trials comparing the one-tunnel vs. two-tunnel techniques have proven that there is no difference in the outcomes. Obviously, more study is needed before one can come to a final conclusion on this matter.

Yasuda: I use double tunnels in the femur. My indications for the anatomical two-tunnel procedure involve all patients who need to undergo primary ACL reconstruction and who want to undergo reconstruction with the hamstring tendon autograft.

Renström: What was your rationale to change to this technique?

Yasuda: Clinical results after one-tunnel ACL reconstruction have greatly improved in the past 10 years. However, there are still many issues that should be addressed [with the one-tunnel technique] in the near future.

This image shows the tibial guide being used to carry out the tibial tunnel. The ends of the thread are wound around both fingers of the surgeon, while the assistant performs knee movements of flexion and extension. When there are no changes in tension, the position is isometric. COURTESY OF RAMON CUGAT

The normal ACL is composed of the anteromedial bundle (AMB) and the posterolateral bundle (PLB). We found that these two bundles have different functions in the range of knee motion according to our basic study, and the PLB contributes to knee stability in the flexion range less than 45º (Kurosawa et al, Clin Orthop., 1991). Therefore, I hypothesized that if we can anatomically reconstruct both the AMB and the PLB, the clinical results after ACL reconstruction may be much better.

I began a basic study to develop the anatomical two-route reconstruction procedure of the AMB and the PLB in 1999 and started a clinical trial of this new ACL reconstruction in 2000 (Arthroscopy, in press). I then obtained short-term follow-up results in 2002 that I presented at the 2003 ISAKOS meeting, which showed that postoperative knee stability after the anatomical two-route procedure was better than that after the conventional one-route procedure using the hamstring tendon autograft. Also, the postoperative tunnel enlargement occurs less frequently in the anatomical two-rotue procedure. In addition, I did not experience any obvious disadvantages with [the two-tunnel] procedure. Therefore, I changed to the anatomical two-route procedure in 2002.

Theoretical possible advantages of the anatomical two-route procedure, based on our biomechanical studies, include good control of rotary stability internally and externally, and acceleration of graft remodeling and tendon/bone healing due to the use of the thinner two grafts.

Renström: How do you fix your grafts in the femur?

Paessler: I use the pressfit technique, with no implants except for short or thin tendons.

Yasuda: When I use the double hamstring tendon grafts, I connect a soft, meshed and strong polyester tape at each end of the tendon graft using the original technique as described in the American Journal of Sports Medicine in 1995 and 1997. We have named it the “hamstring tendon hybrid graft.” The femoral end of the tape portion is fixed with an endobutton attached directly to the tape so that only the hamstring tendon portion is grafted across the knee joint. The tibial tape portion is fixed with the “turnbuckle” stapling technique using two spiked staples. I consider this technique useful for the double-bundle reconstruction. Our colleagues reported that the maximum load of such a femur-graft-tibia complex is approximately 900 N, which is stronger than that of a femur-graft-tibia complex with the BTB graft.

Renström: Are there any technical difficulties to point out with a two-tunnel technique?

Yasuda: There are no essential difficulties between the one- and two-route procedures if surgeons are accustomed to the one-route ACL reconstruction technique and if they use good tools to help insert the guide wires. However, I am afraid that many surgeons may misread the intraarticular anatomy of the normal attachment of the AMB and the PLB in the arthroscopic visual field.

Renström: Is a two-bundle graft necessary and beneficial?

Aglietti: I don’t know yet if a two-bundle graft is the right answer, but I think that more improvements are needed in ACL surgery to reach perfection. Most ACL patients do not return to the same sports level and complain about some residual laxity and don’t feel the knee is “normal.”

Cugat: The future goal of ACL surgery will be to reproduce the patient’s anatomy, and so, in my opinion, it will be carried out with three bundles: anteromedial, posterolateral and intermediate.

Johnson: It is unknown if the two-bundle approach is either necessary or beneficial. The reason for this is that the technical [challenges] of using the two-tunnel technique may be so great that the other variables involved — including tensioning of the grafts in the two tunnels or the division of the soft tissue portion of the graft into two different attachment sites — may lead to technical difficulties that negate the potential of getting a two-bundle graft in the correct position.

Another question to ask is, “Is it necessary to have a single tibial tunnel or double tibial tunnel as well as femoral tunnels?” The answers to these questions are just not available.

Renström: What can be improved and what further research is needed in today’s ACL surgical technique?

Yasuda: I believe that control of the positive pivot-shift test is currently not sufficient, and many patients feel some discomfort or unstable sensation during their postoperative athletic activities. Meanwhile, in other patients, the graft is elongated during the postoperative rehabilitation period because of unknown causes.

In addition, control of the secondary meniscus injury and secondary osteoarthrosis is not sufficient, and it takes a long time after ACL reconstruction for graft remodeling.

Twenty years ago, orthopaedic surgeons could not anticipate today’s advances in ACL reconstruction. But, if we are completely satisfied by our current results in ACL reconstruction and consider that the problems I just described are unsolvable, we will not be able to advance the field over the next 20 years.

I believe that more studies on surgical techniques and basic biological technologies are needed.

Cugat: In terms of biomechanics, the future target should be the most precise positioning of the femoral and tibial anchorage possible. This means that, once the plasty of the new cruciate ligament is in place, the same tension can be maintained during flexion and extension.

In more extreme circumstances — for example, in cases of geno-recurvatum — the positioning of the tibia should be lightly posterior, or a roof plasty should be performed in order to avoid the excessive stretching of the plasty in hyperextension. Using this technique would avoid residual instability.

More research is also needed on treatments such as plasma-rich growth factors, stem cells and gene therapy in order to achieve a biological healing.

Aglietti: I think that most of the efforts must be directed to control residual rotation laxity after ACL reconstruction. Another field of research that needs to be addressed is the objective evaluation of results involving new technologies and devices.

Paessler: More than 100,000 ACL reconstructions are performed annually in the United States. Despite the improvements in surgical techniques, a significant number of patients require revision surgery.

Consequently, it is necessary to develop ACL reconstruction techniques without any hardware. Such techniques not only significantly reduce the overall cost, but they facilitate revision surgery and postoperative MRI.

In order to eliminate the postoperative residual pivot shift and to minimize ACL surgery failure, more anatomical reconstruction procedures should be developed in the future. Two-bundle techniques may be a useful option in this matter.

Also, recent advances in our understanding of molecular biology and genetics may influence the clinical practice of ligament surgery in the future.

Johnson: At this time, there is still controversy about the ideal tunnel position and whether it is single bundle or double bundle. There is no clear indication that one graft is superior to another. There are so many other variables such as tensioning, positioning when tensioning and rehabilitation variables that we really do not know which method is best.

The only way to prove which is best is to continue to design randomized clinical trials with enough cases to have the power to show that one particular method is superior to another. Although this methodology is tedious and costly, it is only with this type of technique that we will be able to truly prove which method is best.