The ECU tendon is on the back of the wrist on the small finger side. The ECU tendon is a common source of wrist pain, as there are many problems that can affect it.
The ECU tendon can get pinched in its tunnel or sheath. This is similar to DeQuervain’s tendinitis, or trigger finger. ECU tendinitis is often a result of overuse, leading to swelling of the ECU tendon’s lining, which now takes up extra space in the tight ECU sheath. Initial treatment of ECU tendinitis consists of a wrist splint, an injection, and avoiding lifting with the palm down. Lifting with the palm up stresses the ECU tendon less. If non-operative treatment doesn’t work, the ECU tendon can be released. ECU sheath release is a quick, simple outpatient procedure that is similar to a DeQuervain’s release or a trigger finger release (see video). After surgery, the wound should be kept clean and dry for 48 hours, and then showering is allowed. After surgery, there are no formal activity limitations, but it’s best to “take it easy” for a couple of weeks. ECU releases work very well.
Another ECU problem is degeneration of the ECU tendon insertion, where it attaches to bone. ECU tendon insertion degeneration is also often due to overuse, and is very common in the left hand of golfers. Initial treatment is the same as for when the ECU tendon gets pinched: a splint, a steroid injection, and avoiding lifting with the palm down. If non-operative treatment doesn’t work, surgery is very effective. During this surgery the ECU tendon insertion is transferred about an inch closer to the forearm, and the painful degenerative tendon removed. After surgery, a short arm cast is worn for 4 weeks.
Occasionally, the ECU sheath is deficient or tears off the bone. This leads to a painful snapping of the ECU tendon as it subluxes or dislocates off the back of the wrist. Non-operative treatment is the same as above, but in the case of tendon subluxation has a lower chance of working, especially in active individuals. Fortunately, surgical stabilization of the ECU tendon is very effective. During surgery, the groove that the ECU sits in is deepened and the ECU sheath is reattached to bone. Following surgery, a special cast is worn for 6 weeks. Return to full sports takes roughly 4-6 months, occasionally longer.