Contemporary Management of Knee Chondral Defects, Part IV: Scaffold-Augmented Repair and Osteochondral Allograft Transplantation

Abstract: Scaffold-augmented repair and osteochondral allograft (OCA) transplantation represent hybrid approaches that integrate biologic stimulation with structural support. These strategies are particularly relevant when marrow stimulation alone is insufficient, but joint-preserving alternatives to arthroplasty remain viable. Scaffold-based techniques, including autologous matrix-induced chondrogenesis, enhance marrow stimulation by stabilizing the reparative clot within a three-dimensional matrix. Clinical studies demonstrate improvements in pain and function, and certain scaffolds show superior defect filling compared with microfracture alone. However, long-term comparative durability relative to cell-seeded constructs or autograft transfer remains limited, and improved structural fill does not consistently correlate with superior clinical outcomes. Traditional fresh OCA transplantation provides the most anatomically complete joint-preserving reconstruction by restoring viable hyaline cartilage and subchondral bone in a single-stage procedure. Long-term series support acceptable survivorship in large, osteochondral, and revision lesions, though graft availability, cost, and technical complexity constrain widespread use. Processed and off-the-shelf allograft cartilage products expand accessibility for smaller defects, but are generally supported by early- to mid-term data with limited high-level comparative evidence. Hybrid strategies broaden the cartilage restoration continuum by addressing defects that exceed the limitations of marrow stimulation while avoiding arthroplasty in selected patients. Durable outcomes depend on alignment between lesion size, bone involvement, joint environment, and biologic capacity. As comparative data mature, further clarification of long-term survivorship and cost-effectiveness will refine their role within joint preservation algorithms.