MACI (or matrix-induced autologous chondrocyte implantation) repairs articular cartilage damage by using the patient's own cultured cartilage cells. During an arthroscopy, a cartilage biopsy is removed from a non-weight-bearing area of the joint. The cartilage sample is sent to the laboratory, where the cells are cultured. Afterwards, the cells are seeded on a membrane and finally the membrane with the cultured cells is placed into the defect.

Maci may refer to:

• Maci (footballer)
• Maci Wainwright
• Maci, Guinea