Mosaicplasty versus Matrix-Assisted Autologous Chondrocyte Transplantation for Knee Cartilage Defects: A Long-Term Clinical and Imaging Evaluation  
[PERSON]  
12 nd Orthopaedic and Traumaticologic Clinic, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy; [EMAIL_ADDRESS] (S.Z.); [EMAIL_ADDRESS] (L.A.); [EMAIL_ADDRESS] (D.R.); [EMAIL_ADDRESS] (A.D.M.)  
[PERSON]  
12 nd Orthopaedic and Traumaticologic Clinic, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy; [EMAIL_ADDRESS] (S.Z.); [PERSON]] (L.A.); [EMAIL_ADDRESS] (D.R.); [EMAIL_ADDRESS] (A.D.M.)  
[PERSON]  
12 nd Orthopaedic and Traumaticologic Clinic, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy; [EMAIL_ADDRESS] (S.Z.); [PERSON]] (L.A.); [EMAIL_ADDRESS] (D.R.); [EMAIL_ADDRESS] (A.D.M.)  
[PERSON]  
12 nd Orthopaedic and Traumaticologic Clinic, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy; [EMAIL_ADDRESS] (S.Z.); [EMAIL_ADDRESS] (L.A.); [PERSON]SS] (D.R.); [EMAIL_ADDRESS] (A.D.M.)  
[PERSON]  
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from reconstructive techniques to the more ambitious regenerative strategies [4; 5; 6; 7]. For these surgical approaches, the first procedures described were osteochondral autologous transplantation (OAT) and autologous chondrocyte implantation (ACI), respectively [8; 9]. These techniques demonstrated promising results up to long-term follow-up, but they also showed several drawbacks, such as significant donor site morbidity for OAT [10], and the risk of graft hypertrophy for ACI [11]. Moreover, both procedures were doomed by the complexity and morbidity of the surgical procedure, requiring an arthrotomy, and thus producing a higher risk of joint stiffness and arthofibrosis [12; 13].  
Therefore, these approaches have been further developed to overcome the aforementioned limitations. On the one hand, the introduction of the mosaicplasty technique involved the use of multiple autologous osteochondral plugs of smaller diameter compared to OAT, thus causing lower morbidity, transferred from lower weight-bearing areas to the cartilage defect [14]. On the other hand, matrix-assisted autologous chondrocyte transplantation (MACT) was introduced to overcome ACI drawbacks thanks to the use of different types of scaffolds for chondrocyte culture and the direct transplantation of a bioengineered tissue, a more manageable and stronger implant for an easier and more stable positioning of the cell-scaffold construct [15]. Moreover, both options can be performed through an arthroscopic approach, allowing to reduce patient's morbidity, surgical time, recovery, and complications related to open surgery [14; 16]. Both techniques showed promising short-term results, later confirmed by studies at long-term follow-up [17; 18]. Mosaicplasty was suggested to provide better clinical results compared to MACT at short-term [19], but data on long-term comparison between these two techniques are still lacking.  
The aim of this study was to compare the clinical outcomes and the quality of repair tissue provided by mosaicplasty and MACT for the treatment of knee cartilage defects at long-term follow-up.