maci smart journal
Isolated chondral or osteochondral lesions of the knee are regularly found in a population undergoing knee arthroscopy [1,2]. Origins include traumatic injuries, abnormal joint loading, and osteochondritis dissecans among others. Cartilage lesions are often found in association with anterior cruciate ligament injuries, dislocations of the patella, limb malalignment, patellar maltracking and following significant meniscectomy [2-5]. Determining the ideal treatment of these lesions is problematic because it is often difficult to determine whether the patient’s symptoms are caused by the cartilage lesion or by an associated pathology. It has been shown that even in isolation, these lesions may lead to significant pain and disability . Damaged articular cartilage has limited or no healing capacity due its relative metabolic inactivity and lack of blood supply that permits only a limited response to injury [7,8].
These lesions may progress to generalized osteoarthritis over time . Repairing isolated full-thickness cartilaginous defects has been therefore proposed to treat symptoms and prevent the development of osteoarthritis. Successful early treatment of these lesions would be of great benefit to patients as well as the health care system, as long-term morbidity and consequent high use of health service resources could be avoided . Imaging studies facilitate the diagnosis of isolated cartilage lesions. MRI has been established as the diagnostic gold standard and should be considered when a chondral injury is suspected [11,12]. Many treatment options have been developed during the last decades to repair damaged articular cartilage .
The techniques can be grouped as bone marrow stimulation techniques such as drilling , abrasion , microfracture  and autologous matrix induced chondrogenesis (AMIC) ; direct chondral replacement techniques such as mosaicplasty , fresh osteochondral allograft transplantation , and periosteal transplantation ; and culture-based techniques such as Autologous Chondrocyte Implantation (ACI)  and Matrix-induced Autologous Chondrocyte Implantation (MACI) .
Each of these procedures can be performed in association with new techniques, materials, or growth factors, leading to the description of a huge number of treatment options that have been used in experimental and clinical settings . This review will provide an overview on the historical development of cartilage repair. The main focus will be on the MACI technique and its variants and the clinical evidence for its use