There has been a recent increased interest in using biologic agents to aid in the treatment of both surgical and non-surgical orthopedic injuries. Biologic agents include items such as platelet rich plasma (PRP) and stem cells.
Stem cells can be classified by their origin and include embryonic stem cells (which come from embryonic tissue) and mesenchymal stem cells. Utilization of embryonic stem cell tissue is controversial in this country and is limited due to government regulatory restrictions and ethical issues.
Mesenchymal stem cells can come from adult bone marrow, fatty tissue, and tissue associated with a human fetus including amniotic fluid, umbilical cord blood, or the placenta.
Mesenchymal stem cells have the potential to turn into bone, cartilage, and tendon, and are thus very applicable to the field of orthopedic surgery.
- Stem cells obtained from adult bone marrow have the greatest potential to turn into other tissue types but obtaining them is expensive and painful; furthermore as patient’s age the abundance and quality of stem cells in the bone marrow diminishes.
- Stem cells obtained from fatty tissue are abundant and relatively easy to obtain but are limited in their ability to transform into other types of tissues.
- When mesenchymal stem cells are obtained from amniotic fluid, umbilical cord blood, or the placenta, they are referred to as amniotic derived stem cells.
Theoretical Uses for Stem Cells:
Stem cells can be theoretically useful for a variety of conditions treated by orthopedic surgeons but research in his area is early and there is little consensus on the ideal uses for stem cells and the optimal delivery methods. Conditions possibly amenable to treatment with stem cells include the following:
- Osteoarthritis: Because of their regenerative and anti-inflammatory properties, mesenchymal stem cells have been studied in the setting of osteoarthritis. Some early small studies have shown good results but larger studies with longer term follow-up are needed to validate these early preliminary findings.
- Tendinopathy: Tendon disorders such as those affecting the rotator cuff, Achilles tendon, and tennis elbow may be potentially treatable with stem cells but little research has been done in this area.
- Articular cartilage injury: Injuries to the surface lining cartilage of joints, known as articular cartilage, has very poor blood supply and limited healing potential. The addition of stem cells either in isolation or in conjunction with a cartilage repair surgery have shown promising results in early studies.
- Achilles tendon repair: Because the Achilles tendon has very poor blood supply, stem cells have been used in an effort to accelerate the healing and rehabilitation process following Achilles tendon repair surgery.
- ACL reconstruction: Stem cells have been studied in animal models in an effort to improve graft healing in the setting of ACL reconstruction surgery. Early studies have showed no significant improvement, but may have been limited by flaws in the study design and methodology. This is an area of ongoing research.