What is the role of stem cell therapy in the treatment of avascular necrosis (AVN)?

Updated: Dec 05, 2020
  • Author: Sunny B Patel, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

The use of stem cells implanted via core decompression has been studied for the treatment of early-stage (precollapse) AVN of the femoral head. [37, 38, 39]  For example, Pilge et al reported benefit with the application of autologous bone marrow concentrate, derived from iliac crest aspirates. In this study, compared with core decompression alone, the addition of bone marrow stem cells seemed to decrease pain and other joint symptoms, improve range of motion, and prevent collapse of the femoral head. [22]

Hernigou et al reported superior long-term outcome with core decompression plus bone marrow injection compared with decompression alone in the same patient. Their study included 125 consecutive patients (78 males and 47 females) with bilateral corticosteroid-induced AVN. [40]

All patients had AVN at the same stage in both sides (stage I or II); the hip with lower volume of osteonecrosis, as measured with MRI, was treated with core decompression, and the contralateral hip was treated with decompression and percutaneous injection of mesenchymal cells (MSCs) obtained from bone marrow concentration. The average total number of MSCs (counted as number of colony-forming units–fibroblast) in each injection was 90,000 ± 25,000 cells (range, 45,000 to 180,000 cells). [40]

On follow-up conducted an average 25 years after the first surgery (range 20 to 30 years), 35 hips (28%) treated with cell therapy had collapsed, compared with 90 (72%) treated with decompression only. Total hip arthroplasty had been performed in 30 hips (24%) in the cell therapy group, versus 95 (76%) in the decompression-only group (P <  0.0001). [40]

Houdek et al reported beneficial results from injecting the combination of bone marrow–derived mesenchymal stem cells and platelet-rich plasma into the femoral head after standard hip decompression in patients with corticosteroid-induced AVN. In their preliminary study of 35 hips in 22 patients, use of this technique improved pain and function, and more than 90% of femoral heads had not collapsed at a minimum of 2 years. [41]

Systematic reviews of studies with patient-reported outcomes have demonstrated clinical benefit with the use of stem cells for hip AVN, with a low rate of complications, but have highlighted the lack of standardization with this technique. Comparisons across studies have been complicated by differences in etiology and severity of AVN, cell sources and doses, adjuvant therapies used, and outcome assessment methodology. [38, 39, 42, 43]

Although the assumption is that the injected stem cells are taken up and differentiate into osteoblasts, Im points out that the survival of stem cells implanted into the hip has not been studied. In other organs, tracking studies have shown that injected or implanted stem cells usually exert paracrine effects and then largely die off. Measures to improve stem cell survival by enhancing the vascularity and osteogenic potential of the treatment site are currently under study, and include use of adipose stem cells and the addition of angiogenic factors, such as vascular endothelial growth factor (VEGF). [43]

Autologous platelet-rich plasma has been used in conjunction with core decompression in early-stage AVN of the femoral head. A systematic review concluded that adjunctive platelet-rich plasma improves the efficacy of core decompressoin in these patients, especially when combined with stem cells and bone grafts, by inducing osteogenic activity and stimulating the differentiation of stem cells in necrotic lesions. [48]


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