Small-Diameter and Large-Depth Microfracture Improves Cartilage Repair in the Rabbit Osteochondral Defect Model

Previous studies have confirmed that small-diameter microfracture improves articular cartilage repair more effectively than do large-diameter microfracture and that drilling more deeply improves repair tissue quality. However, in microfracture (MF) surgery, the optimal diameters and depths of the holes drilled into the subchondral bone and their influence on cartilage healing are currently unknown. This study established a rabbit osteochondral defect model and treated cartilage lesions with modified microfracture (MMF) applications of different diameters and depths. Cartilage repair was detected through gross observation, histological analyse and immunohistochemical analyse. The results showed that MF with a diameter of 0.4 mm and a depth of 9 mm enhanced cartilage regeneration at 6 weeks after creating an osteochondral defect and resulted in virtually normal cartilage healing at 12 weeks. The repaired cartilage in the MMF group (diameter 0.4 mm and depth 9 mm) was more hyaline-like than those in the defect and other microfracture groups. In summary, this study confirmed that small-diameter and large-depth MMF could promote cartilage repair.