Abnormalities in the Replicative Capacity of Osteoblastic Cells in the Proximal Femur of Patients with Osteonecrosis of the Femoral Head

VALÉRIE GANGJI, JEAN-PHILIPPE HAUZEUR, ANDRÉ SCHOUTENS, MAURICE HINSENKAMP, THIERRY APPELBOOM, and DOMINIQUE EGRISE

ABSTRACT.

Objective. Aseptic nontraumatic osteonecrosis (ON) of the femoral head is a painful disorder that often leads to femoral head collapse due to subchondral fracture. We postulated that alteration of osteoblast function might play a role in the pathophysiology of ON. We evaluated the ex vivo proliferation rate and differentiation capacity of osteoblasts derived from the intertrochanteric region of the femur and of the iliac crest of patients with ON of the femoral head and compared it with patients with hip osteoarthritis (OA).

Methods. We examined the function of osteoblastic cells in cultures derived from bone biopsies of the intertrochanteric region of the femur and of the iliac crest obtained from 13 patients with ON of the femoral head and 8 patients with hip OA. The replicative capacity was assessed by the proliferation rate in secondary culture. The phenotypic characterization was evaluated by the level of alkaline phosphatase activity, the sensitivity to 1,25 (OH)₂ vitamin D₃, and collagen synthesis.

Results. The replicative capacity of the osteoblastic cells of the intertrochanteric area of the femur in ON patients was significantly reduced compared to patients with OA. The capacity of differentiation, however, was not different between ON and OA patients.

Conclusion. The replicative capacity of osteoblastic cells is significantly reduced in the femur of patients with ON. Our results confirm that altered osteoblastic function plays a role in the pathophysiology of ON of the femoral head. (J Rheumatol 2003;30:348-51)

Key Indexing Terms:

OSTEONECROSIS
OSTEOBLAST
FEMORAL HEAD

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From the Departments of Rheumatology, Nuclear Medicine, and Orthopaedic Surgery, Erasme University Hospital, Brussels, Belgium.

V. Gangji, MD, Assistant Professor; J.P. Hauzeur, MDPhD, Associate Professor; T. Appelboom, MD, Chief, Department of Rheumatology; D. Egrise, PhD, Researcher; A. Schoutens, MD, Chief, Department of Nuclear Medicine; M. Hinsenkamp, MD, Associate Professor, Department of Orthopaedic Surgery.

Address reprint requests to Dr. V. Gangji, Department of Rheumatology, Erasme University Hospital, 808 route de Lennik, 1070 Brussels, Belgium. E-mail: vgangji@ulb.ac.be

Submitted April 10, 2002; revision accepted July 23, 2002.

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