**5.1 Arthroscopic surgery**

Arthroscopic surgery is a common orthopedic procedure that is used in the diagnosis and treatment of problems inside a joint. Generally, the cartilage defect is measured with an arthroscopic graded probe, and the size and the shape of the defect are templated using sterile paper or aluminum that is subsequently used to prepare the graft if it is not an injectable gel form [114]. Besides the defect preparation and measurement, most operations can be done under an arthroscopy. Currently, arthroscopic surgery has been widely used for various damaged cartilage treatments such as degenerative meniscal tear [115] and osteoarthritis of the knee [116].

#### **5.2 Open surgery**

Open surgery is used for some arthroscopically inaccessible cartilage defects such as patella, trochlea, posterior femoral condyle, and some scaffolds that cannot be implanted arthroscopically [114]. This technique has been widely used in cartilage tissue engineering for animal surgery and clinical practice.
