Artificial Ligaments

Nicolas Duval, M.D., FRCSC
Duval Orthopaedic Clinic
Laval, Quebec

Anterior Cruciate Ligament (ACL) surgery with an artificial ligament is not commonly performed by Canadian orthopaedic surgeons. The lack of interest in this option is due to various factors, primarily the large number of ligament failures caused by rupture and secondly, synovitis as documented in publications in the 1990s1,2.

The concept of ACL replacement, which is the basis of autograft surgery, turned out to be a failure when artificial ligaments were used. Artificial ligaments cannot be implanted like prostheses. To ensure good, long-term results, artificial ligament implantation must have biological integration . My current technique for ensuring biological integration consists of implanting a small artificial ligament in combination with subacute ACL repair. The artificial ligament acts a reinforcement to allow for ligament healing. To repair the ACL, I use several nonresorbable wire sutures in the ACL stump that are put in place arthroscopically using a Meniscal Viper Repair Kit (Arthrex). I always use fluoroscopy to create the femoral and tibial tunnels, which are usually 5.5mm in diameter, allowing for the implantation of a LARS AC 60 ligament.

The role of artificial ligaments in chronic ruptures of the ACL is generally restricted to ruptures that have healed onto the PCL and where repair can be attempted, or to implantations that combine both autograph and an artificial ligament. In most other cases, implanting an artificial ligament is not recommended since it is only a matter of time before the ligament used alone as a prosthesis will rupture.

It is by following these guidelines that I got involved in various studies pertaining to artificial ligaments3, particularly those from the company LARS (Arc-sur-Tille, France). The study of an initial group of patients who had surgery for various ACL problems demonstrated a high level of satisfaction for this technique with a low morbidity rate4. These results provided justification for conducting randomized prospective studies to compare patellar ligament autographs with LARS artificial ligaments. Preliminary two-year follow-up results from one of these studies have already been published5. All patients will complete a minimum five-year follow-up in December 2006, allowing completion of these studies and publication in 2007. These studies were funded by the LARS company but were conducted independently and without any involvement from the company in how the studies were conducted.

A particularly interesting aspect of artificial ligaments is the development of a new generation of bioactive and biointegrable artificial ligaments. This new generation, resulting from tissue engineering, is a hybrid in which a bioactive polymer is grafted, which allows the synthetic origin of the ligament to be masked and the fibroblast response to the surface of the polyester fibers to be controlled. In vitro studies have demonstrated that synthesized or grafted bioactive polymers modulate the proliferation of cells in a culture model and that this modulation is mediated by binding proteins such as fibronectin and collagen and their conformation6,7. These new ligaments are currently being studied in animal experiments. They should be available for human implantation over the next few years. New prospective studies will then be necessary to determine the role of these new implants in ACL surgery.

References

1. Chaput C., Duval N. The History of ligament substitutes. In: Ligaments and Ligamentoplasties. Yahia H (ed.), Springer-Verlag Berlin Heidelberg; 1997; 143-165

2. Duval N., Chaput C. A Classification of prosthetic ligament failures. In: Ligaments and Ligamentoplasties. Yahia H. (ed.), Springer-Verlag Berlin Heidelberg; 1997; 167-191

3. Duval N. The Future of Anterior Cruciate Ligament Reconstruction. Canadian Orthopaedic Association Bulletin 1999; 46:14-19

4. Lavoie P., Fletcher J., Duval N. Patient satisfaction needs as related to knee stability and objective findings after ACL reconstruction using the LARS artificial ligament. Knee 2000; 7:157-63

5. Nau T., Lavoie P., Duval N. A new generation of artificial ligaments in reconstruction of the anterior cruciate ligament. J Bone Joint Surg Br 2002; 84(3):356-60

6. El Khadali F., Helary G., Pavon-Djavid G., Migonney V. Modulating Fibroblast Cell Proliferation with Functionalized Poly(methyl methacrylate) Base Copolymers: Chemical Composition and Monomer Distribution effect. Biomacromolecules 2002; 3(1):51-56

7. Ciobanu M., Siove A., Gueguen V., Gamble L.J., Castner D.G., Migonney V. Radical graft polymerization of styrene sulfonate on poly(etylene terephtalate) films for ACL applications: grafting from and chemical characterization. Biomacromolecules 2006 Mar; 7(3):755-760.

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