**5.3 Microfracture surgery**

Microfracture surgery is a surgical technique used to repair damaged cartilage by making multiple small holes in the surface of the joint to stimulate a healing response. This technique was developed in the early 1980s by Steadman and his colleagues. The technical details of microfracture have been well summarized [117]. Several animal studies have been completed to assess the microfracture technique [118, 119]. The functional outcomes of patients treated with microfracture for traumatic chondral defects have shown significant improvement [120]. Currently, microfracture surgical

technique is considered to be an effective arthroscopic treatment for full-thickness cartilage defect [121]. However, some studies have shown that the younger patients have better clinical outcomes and quality cartilage repair than older patients [122].

## **5.4 Mosaicplasty surgery**

Mosaicplasty surgery is another common cartilage restoration technique in standard clinical practice. This technique was introduced into clinical application in 1992 [123]. Mosaicplasty surgical technique is based on the mosaic-like transplantation of several small, cylindrical plugs of bone and cartilage to provide an even resurfaced area. The long-term clinical follow-up results have shown that the mosaicplasty-treated patients can regain their pre-injury activity level [124].

The studies have demonstrated that the treatment of mosaicplasty in a single cartilage defect size one to five square centimeters of the femoral condyle resulted in clinically relevant better outcome than microfracture [125, 126].
