The patient is under 45 years of age. Patients who have undergone total or partial meniscectomy and have pain in the corresponding compartment of the knee with a meniscal defect, and who have failed non-surgical treatment, may be considered for meniscal transplantation. In these patients, the “ideal situation” is one in which the lower extremity has a normal line of force, the knee is stable, and the knee is beginning to show early degenerative changes. However, most patients have meniscal injuries with other injuries present. Only about 20% of meniscal grafts are performed alone, and most of these patients also show some degree of cartilage pathology. The remaining 80% of concomitant lesions require surgical treatment. The most common of these are ligament injuries (most commonly ACL, but also PCL, PLC or compound ligament injuries), force line abnormalities (medial compartment of internal knee rotation or lateral compartment of external knee rotation), and chondral lesions (simple Outerbridge degree IV injury with subchondral bone exposure). These cases would require appropriate improvement of the force line or ligament reconstruction in conjunction with meniscus graft surgery. In patients with ACL deficiency, after ACL reconstruction, meniscal transplantation can further improve knee stability due to meniscal deficiency. Some patients do not achieve satisfactory stability after ACL reconstruction alone, and better stability and better knee function can be achieved if a meniscal transplant is performed. There are no obvious signs of osteoarthritis of the knee.