Histological Evaluation of the Effects of Intra-Articular Injection of Caffeic Acid on Cartilage Repair in a Rat Knee Microfracture Model

Background: Cartilage injuries are challenging to treat due to limited self-healing. Standard treatments often lead to the formation of less durable fibrocartilage. Caffeic acid phenethyl ester (CAPE), a polyphenolic compound, can improve cartilage repair. This animal study aimed to evaluate the histological effects of intra-articular injection of CAPE on cartilage repair in a rat model of microfracture of the knee joint. Material/Methods: Twenty-four male Sprague-Dawley rats were divided into 4 groups. A cartilage defect was created in all groups, but Group A received no further intervention. Group B underwent a microfracture. Group C received intra-articular CAPE in the presence of a defect, without microfracture. Group D underwent both microfracture and CAPE treatment. Also, each rat underwent bilateral surgery, with one knee receiving CAPE (150 mu g/kg) and the other receiving a control solution. After 28 days, histological analysis was performed on the cartilage tissue samples obtained from the defect sites by using the International Cartilage Research Society (ICRS-I and -II) visual assessment scale. Statistical analysis was performed using appropriate tests to compare histological scores between groups, with significance set at P<0.05. Results: Intra-articular CAPE significantly improved histopathological outcomes across several parameters, including reduced inflammation (P<0.05), enhanced tissue morphology (P<0.05), and improved cartilage matrix staining (P<0.05). No significant difference was observed in chondrocyte clustering or surface architecture among the groups. Conclusions: Intra-articular CAPE enhances cartilage healing by improving tissue morphology and cartilage matrix quality.