Understanding the Effectiveness of Flexor Tendon Repair Protocols

A recent review of all available research papers concluded that there is really not a straightforward recipe for rehabilitation when it comes to recovery from a flexor tendon repair but that the surgical repair techniques have improved.

Our hands’ intricate system of pulleys and tendons allows us the ability to perform very fine motor tasks such as writing or typing. Your finger flexor tendons control the bending motion that allows us to do these amazingly intricate tasks.

The finger flexor tendons attach onto each individual segment of your finger. Notice how you have three points along your finger that you can bend; your fist knuckle, your finger knuckle and finally the end of your fingertip.  Each of these knuckles is controlled by a separate muscle, which turns into a tendon and connects to your finger bone. Should any of these flexor tendons tear it becomes quite difficult, if not impossible, to perform the usual things we require of our hands without a second thought, unless the tendon is reattached to the bone. 

As it turns out, however, repair of the tendon is just the first step.  The tricky part to total recovery is in the rehabilitation of the finger. Following surgical reattachment of the tendon there are two problems that frequently occur. First, the repair itself can fail and the tendon can tear again.  Secondly, while the site of the repair itself needs to rest and rebuild, the remainder of the tendon is stagnant as well. As we all know, if you stay in a static position for a long time you tend to get stiff. The same is true for your tendon and actual adhesions or a binding down of the tendon can occur which causes a decrease in your strength and ability to bend your finger. The ideal rehabilitation recipe, or protocol, would account for both of these issues by allowing your finger to move without risking tearing the tendon again.

Prior to the 1970’s, protocols called for a three-week period of total immobility because it was thought that repairs tended to fail during that time. Then two things changed in the mid 1970’s.  First, new evidence claimed that some motion–three to five millimeters (about the width of a thin wedding band), was actually beneficial for recovery because it prevented adhesions or binding down of the tendon.  Secondly, another team came up with a simple yet ingenious device that allowed patients to extend their finger themselves (since the extensor tendon on the back of the finger was fine) and a rubber band would pull the finger back to its resting position.  This allowed for active motion, or exercise of the healthy tendons on the back of the finger, and relaxation of the repaired tendon on the palm side.  

Authors of this systematic review analyzed the results of 34 different research papers to compare protocols for flexor tendon repair rehabilitation.  They looked at three trends: the difference in success rates between active motion (the patient moving their own finger) and passive motion (movement with the rubber band-like brace), the rate of tendon re-rupturing, and the overall trends in surgical repair. 

The outcome of the repairs were mixed with the overall failure rate (meaning decrease in motion following the protocol or another actual tendon rupture) being slightly better with the active protocols (11 per cent) than the passive protocols (13 per cent).  Breaking down these percentages makes it slightly more meaningful– for the active protocols five per cent of the failures were due to rupture and six per cent were due to decrease in motion; the passive protocols had a four per cent rupture rate and nine per cent due to a decrease in motion—but these data left the authors unable to conclude which protocol is actually better. 

Reviewing the research available left the authors still wondering what the best balance is between active and passive rehabilitation protocols following flexor tendon repair.  Luckily, they were able to conclude that during the past 25 years overall trend in tendon re-rupture rates after surgery is decreasing thanks to material advances and improved suturing techniques.  So until the perfect protocol is determined at least we know that the rupture rate is decreasing in part to surgical advancements.