Autologous Adipose Tissue-Derived Stem
Cells Induce Persistent Bone-Like Tissue in
Osteonecrotic Femoral Heads
Authors: Pak Jaewoo 
Published: March 2021

Background: Osteonecrosis, also known as avascular necrosis, of the femoral head is a debilitating
disorder that commonly affects 30- to 50-year-old individuals. Currently, definitive treatment is
limited to total hip replacement. However, recent studies have demonstrated bone regeneration in
the femoral head after the infusion of bone marrow-derived mesenchymal stem cells. In addition,
local injection of adipose tissue-derived stem cells has been shown to regenerate medullary bonelike tissue 3 months after treatment. However, there have been no long-term follow-up studies on
humans treated with adipose tissue-derived stem cells for osteonecrosis.
Objectives: To determine if treatment with adipose tissue-derived stem cells and platelet-rich
plasma leads to the regeneration of medullary bone-like tissue and long-term reduction of hip pain
in patients with femoral head osteonecrosis.
Methods: This report of two clinical cases was in compliance with the Declaration of Helsinki.
Also, the Korean Food and Drug Administration has allowed the use of adipose tissue-derived stem
cells (ADSCs) in medical treatments since 2009. To obtain ADSCs, lipoaspirates were obtained from
lower abdominal subcutaneous adipose tissue. The stromal vascular fraction was separated from the
lipoaspirates by centrifugation after treatment with collagenase. The stem-cell-containing stromal
vascular fraction was mixed with calcium chloride-activated platelet rich plasma and hyaluronic acid,
and this mixture was then injected into the diseased hip. The affected hip was reinjected with
calcium chloride-activated platelet rich plasma weekly for 4 weeks. Patients were subjected to preand post-treatment magnetic resonance imaging (MRI) scans.
Results: Two patients (34- and 39-year-old men) with femoral head osteonecrosis and severe hip
pain were treated with adipose-derived stem cells. The MRI scans of the affected hip in both patients
showed segmental areas of low signal intensity (T1 axial views) in the subchondral bones with a
“double line sign” consistent with osteonecrosis. The visual analog scale score, physical therapy
testing, and Harris Hip score of both patients improved after stem cell treatment. Both patients
also demonstrated post-procedure improvement in their MRI scans, evidenced by positive T1 signal
changes consistent with medullary bone regeneration. Further, the long-term reduction in hip pain
was correlated with the MRI findings indicative of bone regeneration.
Limitations: A biopsy of the regenerated tissue was not conducted in either patient. Thus, the
true nature of the treatment-induced changes is unknown. Further, the MRI results may contain
artifacts due to the difficulty in capturing the exact treatment location. It can only be speculated that
there was neovascularization to support the newly regenerated medullary bone-like tissue.
Conclusion: These 2 cases demonstrate the presence of sustained, regenerated medullary bonelike tissue in 2 severely necrotic femoral heads and suggest that this rather simple, minimally invasive
percutaneous procedure may hold great promise as a therapy for patients with femoral head
osteonecrosis.
Key words: Femoral head osteonecrosis, avascular necrosis, bone necrosis, cell-based treatment,
bone regeneration, hip pain, adipose tissue-derived stem cells, ADSC.