Histological changes of the acetabular labrum in coxarthrosis: labral degeneration and repair.

Introduction: The current study was designed to describe types of histological changes within the acetabular labrum in the advanced stages of coxarthrosis, in patients requiring total hip arthroplasty (THA).

Methods: 77 consecutive patients without systemic disorders or prior hip surgery, scheduled for THA with 3 types of coxarthrosis: avascular necrosis (AVN), idiopathic, and dysplastic coxarthrosis were analysed. Patient's data: age, gender, side of the involvement, duration of the symptoms were recorded, and standard anteroposterior (AP) radiographic views of the pelvis were obtained. During THA procedure the acetabular labrum was harvested and examined histologically and immunohistochemically. The mean chondrocytes number and density were calculated using morphometric techniques.

Results: In 77 analysed acetabular labra the following histological changes were found: heterogenic matrix, foci of granular matrix breakdown, pseudocysts, intralabral c alcifications, chondrocyte apoptosis, inflammatory reaction with lymphocytes infiltration and macrophages infiltration and vascular proliferation with 2 stages of maturation: endothelial cell formation and fully formed blood vessels. The average chondrocytes density was 478 cells in 1 mm2 and significantly decreased with age.

Conclusions: The acetabular labrum is an important part of the process of degeneration of the hip in osteoarthritis (OA). Vascular formation and cellular infiltration found in the damaged fibrocartilage may represent a labral response to degenerative changes.