Abstract
Purpose To compare the macroscopic, histological, and immunohistochemical characteristics of the repair tissue of chondral defects treated with microfracture and nanofracture in an ovine model. Methods Full-thickness chondral lesions were created in the medial femoral condyle of both knees in four adult sheep and were treated with microfracture on one side and with nanofracture on the contralateral side. Chondral repair was assessed after 12 months by macroscopic, histological, and immunohistochemical analyses. Results Histological cartilage repair significantly improved in the samples treated with nanofracture for cellular morphological characteristics and cartilage architecture. The immunohistochemical analysis showed a significantly higher immunoreactivity to type II collagen in the defects treated with nanofracture. Conclusion Nanofracture provided better repair tissue than microfracture, with a more satisfactory cartilage architecture renovation and tissue having greater type II collagen content. Clinical Relevance Mesenchymal stem cell stimulation is the most frequently used primary cartilage repair procedure. Nanofracture represents a novel technique to stimulate bone marrow that results into a successful repair of chondral defects.