As the largest intra-articular knee ligament, the posterior cruciate ligament (PCL) is rarely torn in isolation, given the required force to tear it. For high-grade PCL tears unresponsive to conservative treatment or with concomitant ligament tears, the PCL should be reconstructed. Understanding the anatomy and biomechanics of both bundles of the PCL facilitates successful ligament reconstruction. Although various surgical techniques have been studied for either biomechanical or clinical superiority, the selection of the optimal graft in PCL reconstructions remains largely surgeon preference. This review serves to summarize the current understanding of PCL reconstructions with an emphasis on allograft usage and outcomes. 
Comprehensive studies on the exclusive use of allografts for medial collateral ligament (MCL) and posterolateral corner (PLC) reconstruction are limited. This review assessed clinical and functional outcomes of allograft use for MCL and PLC reconstruction. The PRISMA guidelines were followed. A systematic search of the literature was performed in PubMed, MEDLINE, Web of Science, Cochrane (CENTRAL), and Scopus databases to identify published articles on clinical studies relevant to MCL and LCL reconstruction with the use of allografts. The results of the eligible studies were analyzed in terms of stability and functional outcomes, Lysholm score, objective and subjective International Knee Documentation Committee (IKDC) scores, Tegner activity scale, Cincinnati Knee Rating System, Marx score, complications, and graft failure. Nineteen studies with 547 patients undergoing LCL reconstructions using allografts were analyzed. The most common allograft used was the Achilles tendon. Mean lateral opening improved from 6.21 mm preoperatively to 1.88 mm postoperatively, with IKDC and Lysholm scores increasing significantly (44.02 to 74.78 and 53.44 to 85.68, respectively). The failure rate for LCL/PLC reconstructions was 11.13%, and complications occurred in 19.75%. For MCL reconstructions, 5 studies with 135 patients showed a reduction in medial opening from 9.7 mm to 2.33 mm, with increases in IKDC and Lysholm scores (49.8 to 75.92 and 69.3 to 85.46, respectively). The failure rate was 4.19%, with a 10.93% complication rate. The use of allografts for LCL and PLC reconstruction demonstrated satisfactory outcomes, with stable and functional knees, though there was a relatively high graft failure rate. Similarly, positive results were observed in MCL reconstruction with allografts. 
Transplantation of fresh osteochondral allografts is a possible biological resurfacing option to substitute massive bone loss and provide proper gliding surfaces for extended and deep osteochondral lesions of weight-bearing articular surfaces. Limited chondrocyte survival and technical difficulties may compromise the efficacy of osteochondral transfers. As experimental data suggest that minimizing the time between graft harvest and implantation may improve chondrocyte survival rate a 
Meniscus allograft transplantation restores knee function and alleviates pain in symptomatic patients with irreparable meniscus loss, particularly in younger individuals without advanced arthritis. Surgical techniques such as bone bridge, bone plug, and all-soft tissue aim to replicate native meniscus root attachments for optimal biomechanical restoration and graft stability. Clinical outcomes and return to sport rates are generally quite favorable, with no clear advantage of one technique over the others. Debate continues about proper methods for tissue processing, sizing, and rehabilitation protocols; ultimately, the choice often relies on the surgeon’s preference and graft availability. 
Meniscal damage increases contact stress to the underlying chondral surface, leading to cartilage degeneration. However, meniscal repair is not always feasible, and partial meniscectomy is still the current standard of care for irreparable symptomatic lesions, including failure of primary repair. This approach can lead to the development of early osteoarthritis and irreversible knee damage in the long term. The main goals for treating the post-meniscectomy deficient knee are to allow pain-free daily activities, prevent swelling, and avoid further joint degeneration. The concept of meniscal regeneration has become very appealing. This process requires a scaffold for successful migration and colonization with precursor cells and vessels, leading to the formation of organized new meniscal tissue. Two meniscal scaffolds are available: one is composed of aliphatic polyurethane named Actifit, and the other is based on collagen type I fibers called Collagen Meniscal Implant. Both provide an effective and safe solution for treating symptomatic patients with segmental mid-substance meniscus defects. Recent literature has demonstrated that scaffolds are effective both in mid- and long-term outcomes and significantly improve patient satisfaction and clinical evaluation; therefore, they are suggested for meniscus preservation and long-term knee health. 
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