Femoral and tibial condyles were dissected separately without damaging the cartilage surface, and then stained with India ink to assess cartilage degeneration. Quantification of macroscopic images was evaluated by the area of macroscopic cartilage degeneration. Macroscopic pictures were taken using a ZEISS Stimi 2000C microscope (Carl Zeiss, Oberkochen, Germany) on a dedicated medical photography platform. The degeneration area of the medial tibial plateau was measured using AxioVision Rel software version 4.8 (Carl Zeiss, Oberkochen, Germany). Macroscopic assessment was performed separately by two examiners and the average values were recorded.