Articular cartilage is a challenging tissue to reconstruct or replace principally because of its avascular nature; large chondral lesions in the tissue do not spontaneously heal. Where lesions do penetrate the bony subchondral plate, formation of hematomas and the migration of mesenchymal stem cells provide an inferior and transient fibrocartilagenous replacement for hyaline cartilage. To circumvent the poor intrinsic reparative response of articular cartilage several surgical techniques based on tissue transplantation have emerged. One characteristic shared by intrinsic reparative processes and the new surgical therapies is an apparent lack of lateral integration of repair or graft tissue with the host cartilage that can lead to poor prognosis. Many factors have been cited as impeding cartilage:cartilage integration including; chondrocyte cell death, chondrocyte dedifferentiation, the nature of the collagenous and proteoglycan networks that constitute the extracellular matrix, the type of biomaterial scaffold employed in repair and the origin of the cells used to repopulate the defect or lesion. This review addresses the principal intrinsic and extrinsic factors that impede integration and describe how manipulation of these factors using a host of strategies can positively influence cartilage integration. Keywords IntroductionArticular cartilage is a highly organised avascular and aneural tissue that provides a smooth surface for the movement of articulating bones and transmission of loads (Muir, 1995). Cartilage carries out the latter function by transferring the forces generated by locomotion to the underlying bone. The resident cells of articular cartilage are chondrocytes that are surrounded by an extensive extracellular matrix whose primary constituents are water, aggrecans and type II collagen. Aggrecans are rich in covalently bonded glycosaminoglycans that are hydrophilic and whose electronegative properties resist applied compressive forces. The tensile strength required to constrain the electronegative force generated by the aggrecans is provided by an organised network of crosslinked fibrils principally containing type II collagen. In cross-section articular cartilage displays a pseudostratified appearance composed of three unmineralised layers; the superficial zone with small, dicoidal chondrocytes aligned parallel to the surface, a transitional zone where chondrocytes are rounded with no apparent organisation and the radial/deep zone where large chondrocytes are aligned in columns of 4-6 cells at right-angles to the surface, Figure 1. The fourth layer is the calcified zone where mineralisation is restricted to the interterritorial matrix of chondrocytes. The calcified zone borders and interdigitates with the subchondral bone. Cartilage defects TraumaIn younger patients who have generally suffered trauma to a joint, focal lesions may appear that if untreated may lead to further progressive degeneration over time. Clinically, focal lesions are graded from the appearance of superficial fissure...