TREATMENT OF OSTEONECROSIS OF THE FEMORAL HEAD WITH IMPLANTATION OF AUTOLOGOUS BONE-MARROW CELLS: FIVE YEAR FOLLOW-UP

Abstract

Introduction: Osteonecrosis (ON) of the femoral head is a disorder that can lead to femoral head collapse and subsequent total hip replacement. Core decompression is the most widely prescribed treatment for early stage ON but its efficacy is still controversial. Since ON might also be a disease of mesenchymal cells or bone cells, the possibility has been raised that bone marrow containing osteogenic precursors could be implanted into the necrotic lesion. The 2 year results of this controlled double blind pilot study of the effect of autologous bone marrow-mononuclear cell implantation into the necrotic lesion of the femoral head were encouraging but needed to be confirmed by long term follow-up.

Methods: We studied 19 patients suffering from stage 1 or 2 ON of the femoral head. Within this group, 24 individual hips were allocated to a program of either core decompression (control group) or to core decompression plus autologous bone marrow mononuclear cells implantation (bone marrow graft group). The treatment group was blinded to both patients and assessors. Primary outcomes sought were safety and feasibility. Feasibility of treatment was defined as; reduction in pain, improvement in joint symptoms, and a reduction in the progression of the ON from stage 1or 2 to subchondral fracture (stage 3).

Results: After 60 months, there was a significant reduction in pain, measured on a visual analog scale within the bone marrow graft group. There was also a significant reduction in joint symptoms measured by the Lequesne index and the WOMAC score over the same period. Bone marrow implantation reduced the number of hips monitored in this study that progressed to subchondral fracture (stage 3). In the bone marrow grafted group, 10 of the 13 hips remained at the stage 2 but only 3 of the 11 hips in the control group remained stable. Survival analysis showed a significant difference in the time to collapse between the two groups.

At 60 months, 3 of the 11 hips in the control group needed total hip replacement whereas only 2 of the 13 hips in the bone marrow graft group underwent prosthetic replacement.

Discussion: Long term results confirmed that autologous bone marrow-mononuclear cells implantation into the necrotic lesion could be an effective treatment of osteonecrosis of the femoral head.