Efficacy of one-stage cartilage repair using allogeneic mesenchymal stromal cells and autologous chondron transplantation (IMPACT) compared to nonsurgical treatment for focal articular cartilage lesions of the knee: study protocol for a crossover randomized controlled trial. - Korpershoek, J. V.; Vonk, L. A.; Kester, E. C.; Creemers, L. B.; de Windt, T. S.; Kip, M. M. A.; Saris, D. B. F.; Custers, R. J. H. (Trials, 2020)