Fracture Recovery: A Stem Cell Case Study

Bailey, a 12-year-old Quarter Horse mare, presented to the University of California, Davis, Veterinary Medical Teaching Hospital with a severe fracture of her right front long pastern bone. Although the prognosis for saving her life was guarded, the owners elected to pursue treatment. Veterinarians started with a CT scan to assess blood supply around the fracture and better understand the complexity of the injury.

Dislocation radiograph

A lateral X ray showing that once the pins were removed the pastern joint partially dislocated. Tearing of the supporting ligaments by the sharp bone fragments when the fracture occurred caused this instability in the pastern joint, which complicated the overall recovery.

The fracture was repaired with bone screws, and surgeons placed two bone pins in the cannon bone above the fracture. They put her leg in a cast to help protect the fixation during the healing period.

Bailey recovered in a sling and was placed in a hospital stall for postoperative care. Because of the severity of the fracture, a decision was made to use stem cells to enhance fracture healing. Bone marrow was taken from her sternum and submitted to the UC Davis Regenerative Medicine Laboratory for expansion of stem cells 12 days after surgery, in preparation for local injection during the first cast change at 26 days post-surgery. At that time, stem cells were injected through needles placed through the skin into the fracture site at four locations. Radiographs were used to direct accurate placement of the stem cells. The leg was placed in another pin cast to protect the repair for an additional four to eight weeks.

Bailey had several setbacks through the entire healing process. The main complication, which was not noted during the initial surgery, was severing of the ligaments from the sharp bone fragments on the back of the fracture. Loss of this ligament support caused her pastern joint to partially dislocate, resulting in instability and pain. The fracture showed evidence of healing at 75 days, but the instability of the pastern joint was still a concern. Although it was likely that Bailey would need an additional surgical procedure to stabilize the pastern, she continued to improve clinically. After 102 days of hospitalization, Bailey went to a local lay-up facility for additional care. She was maintained in a bandage cast for an additional 45 days, at which time the cast was replaced with a heavy bandage to provide continued support.

Remodeling image

The pastern joint has fused with new bone production on the front and sides of the long and short pastern bones. The fetlock joint has also partially fused without a second surgery. Bailey was able to bear full weight without support and was comfortable at the walk.

Bailey continued to improve clinically, and one year after surgery she was bearing full weight without additional support on the limb and she was comfortable at the walk. The final radiographs showed fusion of the pastern joint and partial fusion of the fetlock joint, which allowed her to have a functional limb. Bailey did not show any evidence of laminitis during her entire recovery period. She has reached a level of stability and comfort to allow her to be used for breeding.

Although it cannot yet be scientifically proven that stem cell therapy substantially improved Bailey's chances for recovery, achieving these results without this additional therapy would be very difficult to accomplish. Further research is required to determine the ultimate effect of using stem cells for fracture healing, but this type of therapy is likely to be beneficial for enhancing healing in many types of fracture cases.


Excerpt from The Horse Report, Vol. 26, No. 4, October 2008, Center for Equine Health, School of Veterinary Medicine, University of California, Davis. For more information and articles see

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