Flexor Tendon Lacerations

Flexor tendon injuries can be devastating, life-changing events. The flexor tendons are the ‘ropes’ that make your fingers move. If they get cut, it’s a very big problem. It seems like it should be easy to repair the tendon and get a good result, but it’s not. The problem is that the tendon runs through a tunnel, called the ‘flexor sheath’. It’s a snug fit, so there’s no room left for bulky sutures, a bunched up repair, or scar. And without the sheath the tendon won’t work right. Depending on where it’s cut, the tendon can only live for 2 to 6 weeks before it dies, liquifies and becomes unrepairable. So tendon lacerations need to be addressed relatively quickly.

Sometimes the tendon gets ripped off the bone, like when grabbing onto someone’s shirt or jersey to pull or tackle them. For many reasons, flexor tendon ruptures usually affect the ring finger. Because the tendon can only live for so long before it is no longer repairable, people who wait too long to see if the finger “heals on its own” often miss their chance to get it repaired and need even more complex reconstructions to improve finger function, or need to live their life with a weak finger that doesn’t fully bend.

Flexor tendon surgery should only be done by an experienced hand surgeon, with additional fellowship training in this type of injury. And while the surgery is important, the hand therapy after the surgery is even more important. It is very intense, frequent and inconvenient. It is often necessary to go to hand therapy for 4-5 days a week for the first month, then 3-4 days a week for the next month, and then 2-3 days a week for another month after that. Therapy should start roughly 3 days after surgery, give or take depending on the weekend (ie. if you have surgery on a Wednesday, therapy will often start that Friday or the following Monday, which is fine). If your surgeon want to fix your tendon and then cast or splint you without allowing finger motion for over a week after surgery, find another surgeon, because he/she is simply not current and your finger motion may be permanently compromised from permanent stiffness. While people worry about re-tearing the tendon after repair, with a good modern 6-strand repair with an extra running (epitendinous) stitch around the tendon, this is fortunately rare. Older 2 or 4 strand repairs weren’t as strong, leading to more frequent ruptures and more reluctance on the part of the surgeon to move the finger quicker. With modern techniques stiffness is, by far, more common than failure of the repair. If stiffness occurs, another surgery for scar removal, called a ‘tenolysis’ may be performed after 3-4 months. However, the results are clearly better if you regain good motion after the initial repair without the need for additional surgery.

Because the tolerances are tighter and even a little scar can jam up the tendon mechanism, results in the small finger are never as good as in the other fingers. And the small finger is the most important finger to have good motion in for power grip; hold your small finger straight and try to make a tight fist and you’ll see what I mean.

The key to a good result is to get the tendon treated quickly by a good hand surgeon and a good hand therapist. However, surgery does not have to be performed as an emergency. It’s often best to let the wound ‘settle down’ for a few days before reopening it surgically. Tendon repair within 2 weeks is optimal. Any nerves that have been cut can be repaired at the same setting. If only one of the finger’s two arteries is cut, it is usually not repaired because the back-flow from the other, intact, artery will cause it to clot and occlude.

As with many aspects of orthopaedic surgery, modern understanding and techniques have greatly improved our ability to help patients. And despite all of the difficulties inherent in treating flexor tendon injuries, in the hands of a good qualified hand surgeon teamed with a good certified hand therapist and a motivated and compliant patient, very good results can usually be achieved.