Effect of Systemic Administration of Granulocyte Colony-Stimulating Factor on a Chronic Partial-Thickness Cartilage Defect in a Rabbit Knee Joint.

Objective: Cartilage lesions in the knee joint can lead to joint mechanics changes and cause knee pain. Bone marrow stimulation (BMS) promotes cartilage regeneration by perforating the subchondral bone just below the injury and inducing bone marrow cells. This study aimed to investigate whether systemic administration of granulocyte colony-stimulating factor (G-CSF) with BMS improves repair of chronic partial-thickness cartilage defects (PTCDs).

Design: Eighteen 6-month-old New Zealand white rabbits were divided into 3 groups: control (C, = 6), BMS alone ( = 6), and BMS + G-CSF ( = 6). Partial cartilage defects with 5 mm diameter were created in the trochlear region of both knees; after 4 weeks, the BMS alone and BMS + G-CSF groups underwent BMS; G-CSF (50 µg/kg) or saline was administered subcutaneously for 5 days starting from 3 days before BMS. At 8 and 16 weeks after cartilage defect creation, the area of cartilage defects was macroscopically and histologically evaluated.

Results: International Cartilage Repair Society (ICRS) grades for macroscopic assessment were 0, 0.7, and 0.7 at 8 weeks and 0, 1.2, and 1.3 at 16 weeks in the C, BMS, and BMS + G-CSF groups, respectively. Wakitani scores for histological assessment were 9.8, 8.7, and 8.2 at 8 weeks and 9.5, 9, and 8.2 at 16 weeks in the C, BMS, and BMS + G-CSF groups, respectively. The BMS + G-CSF group showed significantly more repair than the C group, but there was no difference from the BMS group.

Conclusions: The effect of BMS and G-CSF on chronic PTCDs in mature rabbit knees was limited.