• Orthopaedic Procedures
• Hip & Knee Conditions
• Sports Medicine

• Orthopaedics
• Orthopaedic Procedures
• Hip & Knee Conditions
• Sports Medicine

An examination of the current and future states of the basic and clinical science of meniscal repair was presented by 2 US researchers. Steven P. Arnoczky, DVM, Michigan State University, Lansing, Michigan, USA, opened the session by discussing what the future may hold in the basic science of meniscal repair.

Even a small amount of meniscus resection changes the function of the meniscus in terms of load transmission, which can overload the articular cartilage, leading to degeneration. The basic concept of successful meniscus repair has remained the same since the late 1970s, requiring healthy meniscal tissue, access to reparative cells, access to bioactive factors (a robust blood supply), and a favorable healing environment (a stable and noncatabolic knee). Although there are well-known factors that represent the “ideal” candidate for meniscal repair (Table 1), anywhere from 69% of medial and 88% of lateral meniscal tears may be deemed unrepairable, even in patients with stable knees [Fetzer GB et al. J Knee Surg 2009].

A study that assessed nearly 1500 patients (mean age, 46 years; 69% men, 31% women) with isolated meniscal tears in otherwise stable knees (73% medial, 19% lateral, and 8% both) revealed a poor success rate of repair, with only 7.3% of medial tears and 12.7% of lateral tears being repairable [Metcalf MH, Barrett GR. Am J Sports Med 2004]. This may have occurred because of damage to the meniscus, as many patients had complex or horizontal degenerative lesions that increased as they grew older.

Dr. Arnoczky then discussed new strategies to treat the “biologically challenged” patient with a damaged meniscus. Such patients include those patients aged > 40 years with (1) meniscal tears in the white-white zone, (2) chronic meniscal tears, or (3) complex tears. Three particularly innovative and potentially valuable meniscal repair strategies that may reduce repair failure in these challenging patients (and all patients) have been devised, which Dr. Arnoczky summarized as all-biologic repair, advanced repair, and scaffold replacement.

Biologic repair, which can eliminate the need for sutures of implants, is one strategy for repairing bucket handle and longitudinal tears in the vascular region of the menisci. Advanced repair—which uses the addition of cells, bioactive factors, or both to optimize the healing environment—might be successfully utilized to repair formerly irreparable bucket handle and longitudinal tears in the avascular zone or even horizontal cleavage lesions. Vascular enhancement techniques include creating vascular access by means of channels, trephine-created cores, or slits; stimulating enhancement through deliberate abrasion of the synovium; adding bioactive factors, such as fibrin clot, platelet-rich plasma, and the injection of recombinant proteins; and performing bone marrow stimulation techniques. One promising targeted therapy is the injection of mesenchymal stem cells (MSCs) into the knee joint rather than having the patient undergo surgery [Pak J et al. Biomed Res Int 2014].

Scaffold replacement utilizes bioinductive scaffolds or meniscal prostheses to regenerate chondroprotection function. This is a potential repair strategy for patients with irreparable complex, oblique, radial, or horizontal tears. MSCs may also have potential value as the basis of meniscal regeneration, with recent published data suggesting that up to 24% of patients who received an intra-articular injection of allogeneic MSCs 7 to 10 days after meniscectomy achieved a ≥ 15% increase in meniscal volume over meniscectomy controls at 12 months [Vangsness CT Jr et al. J Bone Joint Surg Am 2014]. Natural scaffolding in the form of allografts and xenografts, synthetic materials (eg, Actifit, Menaflex, MeniscoFix), and prostheses (eg, NUsurface) have potential merit for the repair of complex, oblique, and degenerative tears. In the future, custom-designed meniscal implants based on baseline magnetic resonance imaging may also be available. Dr. Arnoczky closed his session with a reminder that despite an array of new tools and techniques, the goal of meniscal surgery is, first and foremost, chondroprotection.

Kurt P. Spindler, MD, Cleveland Clinic, Cleveland, Ohio, USA, then reviewed the present and future clinical aspects of meniscal repair.

The 3 primary options for meniscus tears are excision, repair, or no treatment. The decision that proves best for the patient requires clinical consensus of the severity of the meniscal injury [Anderson AF et al. Am J Sports Med 2011; Dunn WR et al. Am J Sports Med 2004]. A clear understanding of what constitutes successful meniscal repair is crucial. The traditional view of success is no further surgery; follow-up studies have reported appreciable failure rates (14% to 27%) for this approach [Nepple JJ et al. J Bone Joint Surg Am 2012]. Patient-reported outcomes for aspects including pain and activities of daily living—such as the International Knee Documentation Committee subjective knee evaluation score, Knee injury and Osteoarthritis Outcome Score, and the Marx sports activity scale—are reportedly useful, particularly for medial meniscus repair [Cox CL et al. Am J Sports Med 2014; Barenius B et al. Knee Surg Sports Traumatol Arthrosc 2013].

In contrast, a lateral meniscus repair was shown by patient-reported outcomes to be as good as the normal lateral meniscus [Cox CL et al. Am J Sports Med 2014]. The study reported in a 6-year follow-up of 1307 of 1512 (86%) patients (Table 2).

More recently, visualization of articular cartilage changes using specialized radiography views and magnetic resonance imaging has been adopted. A caveat with these visualization approaches is that repair is based mainly on the type of tear and the vascularity of the site of injury; a decision to excise is based on the arthroscopic appearance and the relationship to the blood supply—thus, excision versus repair is not interchangeable. A degenerative meniscus tear from lack of blood supply usually eliminates the option of subsequent repair.

From a clinical standpoint, the future for meniscal repair has 3 main challenges, according to Dr. Spindler. The first is a more complete understanding of the unique roles of the medial versus lateral meniscus, which can affect clinical outcome. Second, there is a need for longer-term data from prospective cohorts to drive improved healing following medial meniscus surgery and to identify replacements for lost medial meniscus. Third, improvements in the evaluation of meniscus repair are necessary. Improvements should include validated patient-reported outcomes and assessments of the performance and appearance of the repaired cartilage.

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