Tendons are highly prone to injury due to their inherent design and function. Relative to other structures, tendons are hypovascular, meaning they have a poor blood supply. Tendons typically have a cross-sectional area that is significantly less than the in-line muscle, and therefore, considerable stress is placed on the tendon, especially during exercise. The primary function of a tendon is to transmit the force of muscular contraction to the skeletal system, thereby generating movement. It is this mechanical force that can lead to excessive stress that causes injury.
Due to these factors, tendons are frequently injured, and the natural healing response is slow and inefficient. The 1999 publication Musculoskeletal Conditions in the United States by Praemer, Furner, & Rice, estimates that $30 billion is spent in the U.S. each year on musculoskeletal injuries, and approximately 45% of these are tendon and/or ligament injuries. In an effort to show just how common tendon injuries are, an article by Sher, et. al., in 1995 entitled "Abnormal findings on magnetic resonance images of asymptomatic shoulders" found an overall incidence of shoulder rotator cuff tears to be 34% across all age groups, even though these patients all had no pain and exhibited normal functional activity. The percentage was smaller in younger patients and increased with advancing age, as 54% of the patients over the age of 60 had cuff tears.
Surgical repair of tendon injuries has become increasingly more common, although such repairs are often unsuccessful. Bishop, et. al., published a study in 2006 called "Cuff integrity after arthroscopic versus open rotator cuff repair: a prospective study" in which they conclude that while small cuff tears have reasonable surgical outcomes, large tears show failure rates up to 75%. Thus, traditional surgey is no guarantee of restored function and elimination of pain.
One factor in the difficult recovery from a tendon injury is that scarring can occur during the healing process. The area of the tendon that scars is never able to be as fully functional as it once was, and is even more prone to re-injury. This is an important advantage in treating this type of injury with stem cells, as the stem cells can be used by the body to grow new tendon instead of scar tissue. This then leads to a functionally superior outcome.
We believe that dual treatment with stem cells (for the reason listed above) and platelet rich plasma (PRP) offers the best possible solution. The stem cells will be used as the body needs them to regenerate tendon, while the PRP gives concentrated growth factors and platelets directly to the site of injury to promote healing. This tecnique is not only useful for rotator cuff treatment, but can be used for any tendon injury (Achilles, "tennis elbow", other shoulder tendons, etc.).
