Abstract
Introduction
Femoral neck fracture (FNF) is a common trauma in the elderly individuals. When the blood supply to the femoral head is impaired with a fracture event, the reduction or disruption of blood supply to the bone, hypoxia, leads to death of the bone marrow and trabecular bone, and eventual late segmental collapse. In the reparative process, osteoblasts and osteoclasts perform the important function of repairing the fracture site at the femoral neck. However, the reparative reaction including angiogenesis and osteogenesis remains unknown. In order to investigate the reparative reaction in patients with FNF, the distribution of tartrate resistant acid phosphatase (TRAP)-positive cells and expression of HIF-1 alpha, VEGF, and FGF-2 were observed in 36 hips in 35 patients.
Methods
There were 6 men and 30 women who had a mean age of 79 years (range, 58 to 94 years). There were 10 hips with Garden stage 3, and 26 hips with Garden stage 4. The mean duration from onset to the surgery was 12 days (range: 1 to 82 days). Hematoxylin eosin staining, TRAP staining, immunohistochemistry using anti HIF-1 alpha, anti VEGF, and anti FGF-2 antibodies were performed for retrieved whole femoral heads. As a control, one femoral head in a patient who underwent wide resection for metastatic acetabular tumor was used.
Results
TRAP-positive cells were detected in 9 hips (25%). They existed around the fracture site in 4 hips, while around the teres insertion and retinaculum in 7 hips. In the control, the TRAP-positive cells were detected slightly around the teres insertion and retinaculum. Around the fracture site, HIF-1 alpha expression was detected in 14 hips (39%) mainly at the vessel epithelium, VEGF was expressed at the edematous area in 28 hips (78%), while FGF-2 was detected widely in the marrow cells in 23 hips (64%). There were significant differences in TRAP staining and in HIF-1 alpha expression between Garden stage 3 and stage 4 hips, although there were no significant differences concerning the preoperative duration after fracture.
Conclusion
TRAP-positive cells were recruited through the teres insertion and the retinaculum around the fracture site. HIF-1 alpha expression was detected at the restricted area around the fracture site, while VEGF and FGF-2 were detected widely regardless of Garden classification.
