Extensor Tendon Subluxation
Extensor Tendon Subluxation / Boxer’s Knuckle
Subluxation or snapping of an extensor tendon on the back of the hand can occur for different reasons. It’s often due to a trauma, such as punching a hard object. That’s why some refer to this injury as ‘Boxer’s Knuckle’. It can also happen when a ball or other object strikes the finger, or from a generalized condition, such as rheumatoid arthritis. The middle finger is most commonly affected.
When moving an injured finger with extensor tendon subluxation, the extensor tendon on the back of the hand snaps back and forth. This is an annoying, sometimes painful problem that can greatly affect hand function. If it’s due to an injury that happened no more than 2 weeks previously, a minimally restrictive brace may help. This can take one of two forms: one is a pen-like cylindrical object under the base of the affected digit, on top of the other fingers. This keeps the injured finger’s metacarpophalangeal (MP) joint, the big joint that connects the finger to the hand, from fully flexing. The other type of brace is bulkier and fits into the palm to prevent the affected MP joint from fully flexing.
However, if the tendon subluxation has been going on for over two weeks, or if it’s due to a generalized issue (like rheumatoid arthritis), bracing will probably not work. In these cases, the extensor tendon subluxation is either accepted or treated surgically. The surgical treatment is an outpatient procedure that is relatively simple, straightforward and usually very effective. A strip of the snapping extensor tendon is used to reconstruct the torn ligament (the sagittal band) that normally keeps the tendon stable. While this procedure does leave a scar on the back of the hand, it’s not very painful. Following surgery, one of the two braces discussed above is worn for 4 weeks. The hand can be used, but full MP joint flexion should be avoided for 4 weeks, except under the supervision of a hand therapist.
After surgery, the wound should be kept clean and dry for 3 days. Bathing is safer than showering, because the hand can be kept out of the bath tub. Wrap a towel around the hand and then place it inside a plastic bag secured with rubber bands. If a bathtub is not available, the best cast protector is made by Walgreens. After 3 days the wound can get wet in the shower, blotted dry, and band-aids or a light dressing that will not limit motion can be applied. Please do not get the wound dirty, or submerge it under water, until the stitches come out, 2 weeks after surgery.
So if a snapping tendon on the back of the hand is causing problems, please know that there is a very simple, effective, and reliable cure for this.