Flexor Tendon Repair for a Zone 2 FDP Tendon Laceration

CHAPTER 1

This is a case of a zone 2 flexor tendon laceration of the right small finger. The patient experienced this laceration with a kitchen knife. He presented to the office with an altered cascade and inability to fully flex his small finger as can be seen here. PIP motion is intact, but DIP motion is lacking, indicating likely FDP tendon laceration. The procedure is being performed in an operating room using a traditional WALANT technique. The patient is awake and alert. He has already been injected preoperatively in the holding area with 9 cc of 1% lidocaine mixed with 1 cc of bicarbonate.

CHAPTER 2

5 cc were injected at the level of the A1 pulley, 2 cc over the proximal phalanx, another 2 cc over the middle phalanx, and 1 cc over the pulp. Those sites are being re-injected here just to make sure that we have a good block and to augment the initial injection.

The laceration site is already marked. Now the skin incision is being marked by incorporating the laceration using Bruner incisions. Alternatively, a mid-axial incision could also be utilized as readily.

CHAPTER 3

Once anesthetized and marked out, the incisions are placed. It's worth noting for a moment why the WALANT technique is being utilized here. Obviously, WALANT provides a number of advantages including safety, convenience, and decreased cost. But in the setting of a flexor tendon repair procedure, there's also the significant advantage of being able to test one's repair to make sure that adequate repair strength has been achieved, that there's no catching or triggering or bunching of the repair site over any of the pulleys, to make sure full composite flexion is achieved, and to show the patient what they can achieve postoperatively with rehabilitation. This is a significant advantage over traditional techniques where the patient is asleep where the repair cannot be challenged intraoperatively.

CHAPTER 4

Once the incisions have been placed, tenotomy scissors are then used to elevate the flaps. Skin hooks are then used to retract the flaps. Once elevated, the flaps can be tagged with silk sutures to help mobilize them and aid in exposure during the case.

With the flexor sheath fully exposed, the sheath is examined and also the digital nerves are examined. Anytime you have a flexor tendon injury, there's a high likelihood of an associated digital nerve injury as well. In this case, both nerves were confirmed to be intact based on direct visualization. Next, the flexor tendons are examined in the sheath. Here, the laceration in the sheath is quite evident, and an intact FDS, or flexor digitorum sublimis, tendon is confirmed, but no FDP, or flexor digitorum profundus, tendon is present.

CHAPTER 5

Therefore, the proximal end of the FDP tendon is sought. Oftentimes it is retracted to the level of the A1 pulley. Here, the A1 pulley is being exposed, and a small opening in the sheath over the A1 pulley is placed in order to retrieve the FDP tendon. Once retrieved, the proximal FDP tendon stump is tagged with the suture. Here, I'm using a 4-0 Ethibond, which is a non-absorbable, braided suture, using a standard modified Kessler technique as shown here. There are a number of ways to repair flexor tendons, and this is one of just many of those techniques. Careful atraumatic tendon handling should be implemented throughout. Here, you'll see that I'm holding the tendon only one time with my Adson's pickup, centrally. I'm avoiding multiple times of grabbing and letting go of the tendon. I'm also trying to minimize the number of times my suture has to run through the tendon. All of these things will aid in hopefully minimizing scarring and adhesions at the repair site.

Next, as was done proximally, the distal stump of the FDP tendon is identified. In this case, the tendon is sitting at the level of the A4 pulley. That pulley is partially taken down in order to expose the tendon for tagging with the similar suture as proximally. Again, atraumatic technique is being emphasized during suture placement in the distal tendon stump as was done proximally. And again, a modified Kessler stitch is also being placed distally as was placed proximally as well. It should also be noted that the pulleys are preserved whenever possible. In this case, a limited opening in the A1 and A4 pulleys were made, but the A2 pulley was completely preserved.

Once tagged, the proximal stump is then brought distally by running it through the remaining pulleys as shown here and making sure that the orientation of the tendon is appropriate relative to the intact FDS tendon. Here, the proximal tendon can be confirmed delivered into the repair site. It is under the FDS tendon proximally, through the chiasm, and now sitting at the level of the laceration site for repair.

The needle is placed through the tendon and the pulley proximally to hold the tendon in position, and the repair is undertaken with the assistant sitting across as shown here. Care must be taken to put the sutures down without excessive tension or bunching. The goal is just for the tendon ends to touch. All of these results in a 2-core strand suture repair. Ideally a minimum of 4, if not up to 6- to 8-core strand repair is preferable. Therefore, additional sutures are placed in either a box stitch or a modified Kessler technique to help augment the repair site as shown here. In this case, an 8-strand core suture repair was ultimately achieved and then reinforced with an epitendinous repair.

However, prior to the epitendinous repair of the suture, the core suture repair is tested with active motion by the patient. Here, the needle in the tendon is removed. The hand is freed. And the patient is asked to actively flex all his fingers, including his small finger to confirm that composite flexion is achieved. And there's no catching or triggering of the tendon in any plane as confirmed here. Again, the patient is awake and therefore able to do this actively. In addition, I typically will show the patient their ability to actively flex the finger as demonstrated here so they can also appreciate that the tendon has been repaired.

[Background] Let's do it. Do me a favor. Roughly make a fist. Keep going, going, going, going, going - relax. Wiggle both your fingers as best you can. Good, now make a fist again. Good, and relax, good. I'm going to just gently… I'll show you as well, so just take all this, all right?

CHAPTER 6

Once satisfied with the repair strength of the core sutures and the excursion achieved, the final repair sutures are placed. In this case, the epitendinous repair is being achieved with a 6-0 monofilament suture in a running fashion circumferentially around the repair site. This helps minimize the bunching of the repair site while also increasing the strength at the repair site. The epitendinous repair is placed in a running, baseball-stitch fashion or locking-stitch fashion circumferentially, starting from the superficial side running deep and then repairing back to itself at the end.

CHAPTER 7

Once satisfied, the wound is washed and closure is initiated. Any various skin closure techniques can be utilized. I typically utilize a 5-0 chromic suture closure in a simple or a horizontal mattress fashion as demonstrated here.

CHAPTER 8

And here is the wound closed. Once closed, a dorsal extension block splint is applied with plaster in the operating room. Here, you can see the wound is dressed sterilely and then covered in Webril prior to application of the plaster.

The splint will be utilized until the patient begins formal hand therapy under the supervision of a hand therapist. At that point, the plaster dorsal extension block splint can be changed to a removable version either with plaster or OrthoBlast, and flexor tendon rehab per protocol will be undertaken utilizing either a modified Duran protocol or an early active motion protocol. The first 6 weeks of both protocols involves protecting the repair site with a dorsal extension block splint for the first 4 to 6 weeks prior to advancing to full composite flexion and extension. Strengthening typically is initiated at 6 to 8 weeks postoperatively. Thank you.