My hand surgeon said it would depend if the ends of the tendon could be found and sewn together again. One end might have recoiled back into my arm. After surgery the surgeon said he found the ends of my ruptured tendon except they were too frayed to be sewn together. For that case, the index finger has two tendons attached. The index finger can still work with one tendon.

My surgeon said he cut one tendon to my index finger and moved it over and reattached it to my thumb. It felt weird after surgery but I'm used to it now.

Surgical treatment is to either place a piece of tendon, taken from elsewhere, between the two ends (Tendon graft) or to take another tendon in the hand and move it to take over the function of the ruptured tendon (Tendon Transfer).

The tendon most often used as a transfer is one of the two extensor tendons to the index finger.