Mallet Finger: Splints, Treatment, & More

These are Dr. Knight’s own words from the video. We corrected the anatomy and drug names the automatic captions got wrong and added the punctuation. Nothing he said was changed, added or taken out.

Dr. Knight: Let's take a look at extensor tendon surgery. First off, let's take a look at the anatomy. The extensor tendons come from the forearm down across the wrist on the top surface and come down and extend the fingers, straighten the fingers out. Flexors bend the fingers.

Extensors straighten the fingers. So we're going to concentrate on the extensors. They come down across the wrist through several compartments, and they can be injured anywhere along this line. So the tendons come across the knuckles, and then out in the finger gets a little complex.

The extensors insert at the base of the middle phalanx at the PIP joint, or that middle joint, and then they split off into two lateral bands that go out and extend that very last joint, or the DIP joint. And the key is with these, with the extensor mechanism in the finger, is it extends those two joints simultaneously. So any injury, whether it's a laceration or a tendon rupture, that can affect that synchronization, uh, between those two tendons, and really cause certain deformities.

So let's take a look now at the mechanisms of injury. Kobe Bryant dunking the ball, um, jamming fingers, volleyball players, uh, basketball players that grab, uh, balls in their hand can jam the fingers. And then there's simple injuries that can, uh, cause torn tendons, such as just simply with a mallet finger, we'll see in a minute, can just simply tucking the sheet, uh, under your bed can just abruptly bend the joint in a different position, calling these very fine, causing these very fine tendons to tear away from the bone, causing deformities.

So let's take a look at actually some of the injuries. Mallet finger, as you can see here. So a mallet finger is, looks like a mallet. The last joint, or the DIP joint, is flexed, and that again occurs usually from tearing the tendon away from the bone.

Let's look at this in more detail on the next image. You can see the extensor tendon. It's really just like a paper thin tendon that's coming right across this joint, attaches to the bone. So what happens is you tear the tendon, as you can see from this red line, and now you can see the broken tendon. So the tendon can no longer straighten the joint, and this actually is pretty painless, unless of course there's more of a crush injury where sometimes the bone tears away from the bone as opposed just the tendon tearing away from the bone.

So how is this treated? Let's take a look. It's called a STACK splint. Now, S-T-A-C-K, STACK splint. And these can come different sizes, they're already prefabricated, and we usually send you to a therapist and they'll put these on, and sometimes they'll make more of a custom one that's lower profile. And the key is we want to hold that joint slightly hyperextended so the tendon has a chance to heal back to the bone. So as you can see here the splint is in place.

It takes about six to eight weeks in place, and if it comes off at any point during that healing period you got to start all over. But this can be effective up to several months from the time of the injury, but the sooner you get the splint on, the sooner the healing period.

So let's take a look now at the next deformity, called a boutonniere deformity. So at the PIP joint, the middle joint, now the tendon becomes torn and forms this boutonniere deformity, a flexion at the PIP joint and hyperextension at the DIP joint, as you can see here.

So let's look a little deeper into what actually is happening. You can see the extensor slip, or the central slip, right on top of the PIP joint becomes torn, and as a result the joint starts to flex, the middle joint, as you can see in the next image. The lateral bands, or these tendon, this tendon along the outside of the joint, starts to actually migrate towards the palm side of the digit and actually becomes a flexor of the PIP joint, and then it becomes too tight. Remember, they're working in unison, and the DIP joint starts to hyperextend.

So how do we treat this? Well, conservatively usually, and we'll put a brace on as you can see in the next image, and it's a PIP extension brace, and this holds that joint, the middle joint, straight, but it allows flexion at the distal joint because that's important to get those tendons back in balance. In some cases though, if it's late, late to come to the doctor, that joint may be fixed, meaning we have to go in and relieve the contracture just to get it straight so those tendons have a chance to heal.

Now let's take a look at the most common tendon injury. You got it, comes from cutting, slicing, saws, anything sharp, penetrating objects that can cut the skin can cut these little tendons. And so commonly what happens is, um, from even from cooking, most common injury is actually getting an avocado pit out of an avocado, is that it involves this awkward maneuver with the tip of the knife, and it can skewer the digit or the, uh, area of the hand or wrist, causing, uh, a tendon laceration.

So let's actually take a look at a tendon laceration. This gentleman had a saw injury, cut across the tops of the knuckles about the, at the base of the index and middle fingers. You can see here this gap. This is the white structure that I'm holding between the forceps or tweezers, is the tendon laceration. You can actually see down into the knuckle joint.

So what do we do? We put several little fine sutures in place to actually sew that back together, as you can see in the next image. Nice tidy repair right here. We close the skin and then place the patient in a splint, uh, for several days, and at the initial post-operative evaluation, that's the time that the hardest part of rehabilitation begins.

So let's take a look now at the postoperative therapy, which is one of the most critical points. Today we're joined by Jeannie Robinson, who's the head therapist at California Hand Therapy here in Beverly Hills, who's going to walk us through the recovery and rehabilitation that's so critical to extensor tendon surgery. So I see you have this on. Tell us, what are the indications, where is the tendon cut in the hand to warrant this gizmo?

Jeannie: Okay, so the tendon is cut in zone four, zone five. This is specific, specifically to the index finger extensor tendon. Um, so this is made so that we can start some early active motion. So early active motion is going to help promote the tendon gliding.

Dr. Knight: Okay. And so zone, again the zone is between roughly this strap and the knuckle here, would be the zones, between the wrist and the knuckle is where you would wear this, right?

Jeannie: Exactly.

Dr. Knight: Okay. And so walk us through kind of the time period that you have to, like you'll start wearing this right soon after surgery, but how long are you in this?

Jeannie: Um, typically you're going to be in the splint for about four weeks. So what this does is allows some graded motion. Right now the splint is set so that we can move the index finger to about 30 degrees flexion at the MP joint, and so each week we're going to allow the motion of that MP joint to be a little greater. Uh, so typically this is worn for about four weeks, and then after four weeks the patient is allowed to make a full fist, so make a full composite fist with wrist extension, and then about five weeks they can move into full composite, uh, fist with wrist flexion.

Dr. Knight: Right.

Jeannie: Uh, and then after that, about six weeks we can start doing some strengthening.

Dr. Knight: Okay. So total recovery, what, three to four months, or how?

Jeannie: Um, I would say, you know, 12 weeks, um, until the patient can do everything that they normally did before the injury.

Dr. Knight: Great. All right. Earlier we also talked about, um, boutonniere deformities. This can be from a laceration, or more commonly from just blunt trauma, jamming the finger. And so she's going to walk us through, this is a splint for a boutonniere injury. So tell us, you know, about this, what's involved and how long I have to wear this.

Jeannie: Okay, so the important thing about this brace is that you have to wear it all the time. We don't want any motion at all at the PIP joint, which is the middle joint. Uh, and typically you're going to have to wear it for about six to eight weeks, and oftentimes I'll make a second splint for the patient to sleep in that just holds the whole, the whole finger, or just the, not the whole finger. So really this is just immobilizing the, uh, PIP joint. Um, so we actually want some motion at the tip.

Dr. Knight: So you want to do this.

Jeannie: Exactly.

Dr. Knight: And that, how often do I do this during the day?

Jeannie: Uh, I have my patients do it every hour.

Dr. Knight: Okay. And then after this comes off, what's the, you know, just regular, it's obviously going to be stiff then, how long do it take, usually what's the average recovery time to get over this kind of injury?

Jeannie: I would say average recovery maybe about six to weeks.

Dr. Knight: Okay, great. And then we have one more injury we talked about earlier. Again, usually it's not from a laceration, it can be. It's called a mallet finger where you tear the terminal tendon out here just, just before the fingernail and the finger droops. Um, this is, as we talked about earlier, there's a STACK splint that we showed a picture of earlier that kind of comes in different sizes like shoewear, and sometimes it doesn't fit properly, and so a lot of times they'll do a custom splint because it fits better, it's lower profile. So tell me again, how do, how does this go? Is this the way it goes on? And...

Jeannie: Yeah, that's perfect.

Dr. Knight: Can you tape it, or you got it?

Jeannie: Yeah, we tape it, cuz we really want this to stay on the finger, and because it's on such a small part of the finger velcro is really not going to cut it.

Dr. Knight: Right, because if it comes off it kind of starts all over, you...

Jeannie: That's true. Yeah, if this comes off, if the finger bends at all, then you have to start from day one again.

Dr. Knight: And how long do you leave the patient in this, typically?

Jeannie: Six to eight weeks, just depending on the healing.

Dr. Knight: Right. All right, this has been very helpful. And, uh, for this and, uh, many other conditions, please check out our website.

Jeannie: All right, thank you.

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