Primary anterior cruciate ligament repair: Current concepts.

The renewed interest in ACL repair over the last two decades stems from advances in modern arthroscopic techniques and clinical studies that have provided evidence that the ACL can reliably heal, and patients can return to sport at a comparable rate to ACL reconstruction patients. The ability to maintain and utilize native ACL tissue, with proprioceptive capabilities, and the smaller drill tunnels needed to repair an ACL leads to an overall less invasive procedure and improved early rehabilitation. Additionally, repair avoids a variety of comorbidities associated with autograft harvest. This current concept review details modern techniques of ACL repair and their current studies, a review on the use of biologic enhancement in ACL repair, and other considerations to appropriately integrate ACL repair into the sports medicine orthopaedic surgeon's practice.

Increasing the Dose of Autologous Chondrocytes Improves Articular Cartilage Repair: Histological and Molecular Study in the Sheep Animal Model.

BACKGROUND: We hypothesized that implanting cells in a chondral defect at a density more similar to that of the intact cartilage could induce them to synthesize matrix with the features more similar to that of the uninjured one. METHODS: We compared the implantation of different doses of chondrocytes: 1 million (n = 5), 5 million (n = 5), or 5 million mesenchymal cells (n = 5) in the femoral condyle of 15 sheep. Tissue generated by microfracture at the trochlea, and normal cartilage from a nearby region, processed as the tissues resulting from the implantation, were used as references. Histological and molecular (expression of type I and II collagens and aggrecan) studies were performed. RESULTS: The features of the cartilage generated by implantation of mesenchymal cells and elicited by microfractures were similar and typical of a poor repair of the articular cartilage (presence of fibrocartilage, high expression of type I collagen and a low mRNA levels of type II collagen and aggrecan). Nevertheless, in the samples obtained from tissues generated by implantation of chondrocytes, hyaline-like cartilage, cell organization, low expression rates of type I collagen and high levels of mRNA corresponding to type II collagen and aggrecan were observed. These histological features, show less variability and are more similar to those of the normal cartilage used as control in the case of 5 million cells implantation than when 1 million cells were used. CONCLUSIONS: The implantation of autologous chondrocytes in type I/III collagen membranes at high density could be a promising tool to repair articular cartilage.

Arthroscopic Delivery of Matrix-Induced Autologous Chondrocyte Implant: International Experience and Technique Recommendations.

OBJECTIVE: To identify consensus recommendations for the arthroscopic delivery of the matrix-induced autologous chondrocyte implant. DESIGN: An invited panel was assembled on November 20 and 21, 2009 as an international advisory board in Zurich, Switzerland, to discuss and identify best practices for the arthroscopic delivery of matrix-induced autologous chondrocyte implantation. RESULTS: Arthroscopic matrix-induced autologous chondrocyte implantation is suitable for patients 18 to 55 years of age who have symptomatic, contained chondral lesions of the knee with normal or corrected alignment and stability. This technical note describes consensus recommendations of the international advisory board for the technique of arthroscopic delivery of the matrix-induced autologous chondrocyte implant. CONCLUSIONS: Matrix-induced autologous chondrocyte implantation can be further improved by arthroscopic delivery that does not require special instrumentation. In principle, arthroscopic versus open procedures of delivery of the matrix-induced autologous chondrocyte implant are less invasive and may potentially result in less postoperative pain, less surgical site morbidity, and faster surgical recovery. Long-term studies are needed to confirm these assumptions as well as the efficacy and safety of this arthroscopic approach.

A peek into the possible future of management of articular cartilage injuries: gene therapy and scaffolds for cartilage repair.

Two rapidly progressing areas of research will likely contribute to cartilage repair procedures in the foreseeable future: gene therapy and synthetic scaffolds. Gene therapy refers to the transfer of new genetic information to cells that contribute to the cartilage repair process. This approach allows for manipulation of cartilage repair at the cellular and molecular level. Scaffolds are the core technology for the next generation of autologous cartilage implantation procedures in which synthetic matrices are used in conjunction with chondrocytes. This approach can be improved further using bioreactor technologies to enhance the production of extracellular matrix proteins by chondrocytes seeded onto a scaffold. The resulting "neo-cartilage implant" matures within the bioreactor, and can then be used to fill cartilage defects.