Meniscal Allografts—Where Do We Stand?

Meniscal transplantation has been recommended for selected meniscus-deficient patients in an effort to forestall progressive joint degeneration. Meniscal allograft transplantation may be considered for patients with symptoms (pain and swelling) due to meniscal deficiency in an effort to prevent progressive articular cartilage degeneration. Medial meniscal transplantation may also be considered during concomitant anterior cruciate ligament reconstruction, since absence of the medial meniscus results in increased forces in the anterior cruciate ligament graft. Contraindications for meniscal transplantation include advanced articular cartilage degeneration (especially on the flexion weightbearing zone of the condyle), axial malalignment, and flattening of the femoral condyle. Patient evaluation should include standing, long-leg radiographs for assessment of the mechanical axis and magnetic resonance imaging with appropriate pulse sequences for evaluation of hyaline cartilage thickness. Fresh-frozen and cryopreserved allografts are currently the most commonly used transplantation materials. Appropriate graft sizing is critical; most tissue banks size the meniscus based on radiographic tibial plateau measurements. Early results of meniscal transplantation indicate predictable improvements in pain, swelling, and knee function; however, no long-term results are available. Poor results have been reported in patients with advanced cartilage degeneration. Objective evaluations often demonstrate some degree of degeneration of the posterior horn of the transplant. Earlier transplantation should be considered for patients with known meniscal deficiency.