Surgery on an injured extensor tendon in a thumb
Is it possible to stitch up a torn long extensor tendon in a thumb?
It is only possible to stitch up a long extensor tendon in a thumb if the rupture occurred with a knife or similar object leaving behind a clean cut. Tendon ruptures which happen due to a previous distal radius fracture or were caused by rheumatoid arthritis on the other hand cannot be stitched up!
Why can a clean cut on a tendon be stitched up whereas a rupture caused by a distal radius fracture cannot be remedied like that?
If the tendon was damaged as a result of a distal radius fracture, the damaged area is not smoothly confined. The damage of the tendon extends over a distance of several centimeters. Within this course the tendon over a distance of three to four centimeters typically appears frayed and is not suitable for sutures.
At the wrist, the long extensor tendon of the thumb appears frayed and lacerated over a long course. The extent of the damage can be seen between the red and the blue arrow.
If one was to cut out the damaged tendon tissue in order to fuse the two tendon ends, the thumb extensor tendon would end up being too short.
So what is the right approach in case of a ruptured thumb extensor tendon?
Two different techniques could be applied in a case like that: The most common technique is to transfer a tendon taken from the index finger. This procedure requires the removal of an extensor tendon from an index finger which then is reattached with the distal end of it to the thumb extensor tendon.
Does this solution retain the stretchability of the index finger?
Yes, the index finger of nearly every human being holds two independent extensor tendons. One of these two extensor tendons may be removed and used as replacement for the damaged thumb extensor tendon.
This procedure in medical terms is referred to as indicis transfer.
The red arrow points towards the transferred tendon of the index finger. The blue arrow points towards the distal phalanx of the thumb.
This image shows a surgical procedure after the fusion of the index finger tendon and the thumb extensor tendon.
What are the options to an indicis transfer?
It is also possible to use a tendon from the forearm with almost equal results. There is a tendon in the forearm (palmaris longus tendon) that has no function. This tendon may be removed through few cross sections and be positioned between the two ends of the thumb extensor tendon. This palmaris longus tendon transplant is also often used when treating flexor tendon injuries. However, ten percent of the individuals cannot benefit from this approach as they do not have a palmaris longus tendon at all. Only about ninety percent of all patients dispose of this tendon that would allow for this surgical option.
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