Healing potential of the cartilage correlates with location on the femoral head: a basic research using a rabbit...

The purpose of this study is to investigate whether healing potential of the femoral cartilage differs according to the site of injury in a rabbit, and whether poor potential of the cartilage repair correlates with the injured site which is not in contact with acetabulum. Furthermore, the efficacy of intraarticular injection of hyaluronic acid into the hip for the cartilage with lower healing potential was evaluated.

Male Japanese white rabbits were used in this study. Via the posterolateral approach, the articular capsule was incised and a 4 × 4 mm chondral defect was made at the load-bearing area (group A) or at head-neck junction (group B), and intraarticular injection of hyaluronic acid was performed to the group B model (group C).

In group A, histological evaluation at 8 weeks revealed that the chondral defect was filled with cartilaginous tissue. However, in group B, the chondral defect was not filled with any tissue and subchondral bone was exposed. In group C, the defect was filled with synovial-like tissue, and smooth surface was reacquired macroscopically. According to the ICRS score, significant differences were detected between group A and group B, group A and group C, and group B and group C. There were no differences in the radiographic findings among the 3 groups.

The cartilage at head-neck junction of the femoral head had poorer healing potential than that at load-bearing area. Administration of HA could be promising for preventing progression of cartilage degeneration even at head-neck junction.