A recent study out of the University of Pittsburgh fits with the evolving picture of serious steroid shots into tendons side effects. I’ve blogged before on how steroid injections have been associated with everything from significant bone loss in women to a suppression of the normal hormones produced by your body to handle stress. It’s still very common for doctors to inject these high dose steroids into tendons. In particular, these steroids shots are often used to treat tennis or golfer’s elbow, despite studies showing side effects. This study showed that steroids hurt tendons by causing tendon stem cells to differentiate into non-tendon cells. Why is this an issue? Believe it or not, your tendons (like every orthopedic tissue from bone to muscles to ligaments) have living stem cells that keep them healthy. They do this by replacing the injured or dead cells through differentiation (read that the tendon stem cells they turn into tendon cells). In this study, the researchers saw that the tendon stem cells wanted to become fat or cartilage in the presence of steroids, which weakens the tendon. They concluded that steroid treatment depleted the stem cell pool and this made the tissue more susceptible to rupture. The results of this recent study fit well with another study published in 2006. Both of these lab based studies also align with a recent study in patients showing that steroid shots for tennis elbow made patients worse in the long-run. The upshot? Avoid steroid shots into your tendons or suffer the consequences of a weakened tendon!