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When you’re talking about the thumb, I will always refer to it as the thumb, index finger, middle finger, ring finger and small finger. Some people refer to these fingers and thumb as digits and sometimes give them numbers. My personal bias is to not do that because sometimes there becomes confusion in terms of talking about the first finger or the first digit. Just a quick review of the basic bone terminology. How many bones are there in the hand? There are
There are two muscle systems which control the movement of your fingers. You have the intrinsic muscles which are the muscles that are actually contained within your hand (meaning the hypothenar muscles, the thenar muscles, the lumbricals in the interossei) and then you have
The ulnar nerve. Again, if you’re looking for reliable sensory zone, the small finger is almost always going to be innervated by the ulnar nerve. So it’s a good sensory zone. For motor, the interossei, the muscles between your fingers which control spreading your fingers apart and
Radial nerve is a little bit trickier because none of the intrinsic muscles of the hand are driven by the radial nerve. So there is no muscle that is contained just within the hand that is run by the radial nerve. From a sensory standpoint, the dorsum of the first web space, the area of skin
For the ulnar gutter splints that I make, again, I will use 4" x 15" plaster splints, ten layers thick, and then what I like to do is I like to cut a little slot out, about the length of the ulnar border of the patient’s hand, demonstrating alternative technique No. 2. You can apply the cast padding directly on top of the plaster if you like. Soak just the plaster alone in a bucket of water and make sure that it is soaked all the way through. I
There are a lot of different techniques you can use to immobilize someone’s DIP joint in extension. One of the more convenient ways of doing it is using one of these prefabricated plastic splints, sometimes called a Stack splint. The nice thing about these is they come in different sizes and all that you need to do to apply it is either a piece of adhesive tape or sometimes you can even use Coban and wrap these on. Again, the
Again, most of the time I will go six weeks full time in extension. I will recheck them in the clinic to see if they’ve got their full extension. If they do, then I will probably go to nighttime splinting only for an additional four weeks. So it’s typically a ten week course of some type of splinting.
One other injury at the DIP joint that you should know about is something that is referred to as "Jersey" finger and it’s sort of the flexor tendon equivalent of a mallet finger. The typical scenario is you’ll have a high school football player who is running and trying to grab someone to
Other DIP joint injuries. Occasionally you will see people with DIP joint dislocations. It’s kind of uncommon. The reason why I bring it up is again this is sometimes a fairly subtle injury. Unlike PIP joint dislocations, where it’s usually pretty obvious what’s going on, a DIP joint dislocation can really look almost normal because usually there’s not a lot of angulation. Sometimes all you’ll see is a little bit of swelling and sometimes they will still be able to actively bend the joint a little bit. If you have any suspicion about it, get some x-rays to confirm your suspicion. Most of these can be reduced pretty easily closed. Usually you can pop them back into joint.
PIP joint injuries. Again, extremely common injuries. You will see hundreds of finger sprains in your career. Typically, when people sprain or dislocate their joints, it is usually from a hyperextension injury where the volar plate gets torn. In some cases, the middle phalanx will dislocate over the dorsum of the proximal phalanx. If you examine these people on x-ray, you will oftentimes see a little fleck of bone and I will show you an example of that that suggests that their volar plate has been avulsed off of the middle phalanx.
If you actually have a dislocated PIP joint, although out in the field a lot of people just pull on them to try to get them to reduce, it’s actually a better idea to try to push the joint back on rather than pull. The reason being that when you pull a joint to try to reduce it, sometimes you’ll actually suck soft tissues into the joint and have soft tissues entrapped within the PIP joint. So it’s typically better to sort of push the joint back into a reduced position and that sort of shoves the soft tissues out of the way and gets you a better chance of getting a clean reduction.
Most dislocations and most bad PIP joint sprains we usually treat with a brief period of immobilization just to keep them comfortable. Maybe a piece of Alumafoam splint and then early range of motion. The PIP joint tends to get stiff quickly and so you want to get them moving. I typically use Coban to buddy tape the fingers together and get them moving early.
Here’s a typical x-ray, lateral view, of a PIP joint sprain. It might be a little bit hard to see but there’s just this tiny fleck of bone down here. These tiny little flecks are nothing to worry about as long as it’s just this tiny little avulsion fragment. This is a classic appearance of a PIP joint
Other PIP joint injuries. Occasionally you’ll see someone whose finger got torqued off to the side and they might have a collateral ligament tear. The way you test for that is just to put a little side to side stress on the joint to test the collateral ligaments. Usually they will be tender over their collateral ligament. For the vast majority of collateral ligament tears, buddy-taping with early range of motion is adequate treatment. Usually you try to buddy-tape it to the finger that’s on the weak side of the collateral ligament. So, for example, if you have a rupture of the ulnar collateral ligament of your index finger because your index finger got pulled away towards your thumb, it’s probably best to buddy-tape it to the middle finger. That helps support it.
The only collateral ligament injury of your fingers that you might want to be a little more cautious with is the collateral ligament on the radial side of your index finger because you need very good strength of that to pinch against with your thumb. So that’s the one where you may be a little bit more cautious and may put in a referral to an orthopedic surgeon or a hand surgeon for an evaluation. Because if somebody ends up with chronic instability of the radial collateral ligament of their index finger that could potentially be a disabling problem. We’ll talk about thumb collateral ligament injuries a little bit later.
PIP joint fractures. We talked about the small bone fleck that you sometime see in those sprains – those volar plate avulsions. Those are no big deal. If you start seeing bigger fracture fragments than that, then those are probably injuries that should be evaluated by an orthopedic surgeon or by a hand surgeon. Those tend to be much more tricky injuries to treat and the results are not nearly as reliable as those small avulsion flecks from finger sprains.
Also, any type of condylar fracture, meaning articular fractures of the proximal phalanx, you have to be very cautious about those. They can look stable when you first see them in the Emergency Room and then over a two to three week period they can slide off. My personal recommendation is that any type of articular injury that you see around the PIP joint, with the exception of those small avulsion flecks, should probably be evaluated by an orthopedist or a hand surgeon.
Here’s an example, again. Sometimes this is the way it will look in your initial evaluation in the Emergency Room. You will see what appears to be a nondisplaced condylar fracture and then over a two to three week period this little piece will start to sag down. Then suddenly you’ll end up with angular deformity, a stepoff inside the joint and at two to three weeks, this starts to become a very difficult problem to treat.
MP joint injuries are certainly less common than the DIP and PIP joint injuries but just to talk about dislocations a little bit, we sort of have two classifications for MP joint dislocations. We sometimes use this in reference to PIP joint dislocations too. There are simple dislocations and there are complex dislocations. When we talk about simple dislocations, we mean that the joint is sort of just barely perched on its normal alignment and it’s just a simple push and the joint reduces. A complex dislocation means there is somehow some soft tissue that has been interposed and this is much more common at the MP joint. So you have to be a little bit careful when you reduce these MP joint dislocations and you reevaluate them.
Oftentimes the volar plate gets stuck inside of the joint and you can get fooled because you’ll sort of feel the joint clunk back in. The hand will look okay and the person will be able to flex their fingers somewhat. The one thing you want to make sure of is after you do this reduction is to get a repeat x-ray and make sure that that joint looks perfect. If you see a little bit of increased joint space in between the MP joint where you just reduced it don’t think that it’s just a little bit of soft tissue swelling and a little bit of hematoma in there. That’s usually not the case. If you see a little bit of widening of that joint space then probably the volar plate is stuck inside the joint and it probably needs to be operatively reduced. So just a little warning there on MP joint dislocations.
MP joint dislocation. If you look at this lateral view, here’s the small finger metacarpal and there’s nobody home over the top of it. If you look here on this oblique view, here is his finger dislocated dorsally off of his MP joint. This one was actually reduced closed without difficulty.
Additional thumb MP joint injuries. We talked about collateral ligament injuries of the fingers. The ulnar collateral ligament of the thumb is similar to the radial collateral ligament of the index finger. It’s a very important ligament in terms of stability of pinch for your thumb. It’s the collateral ligament on that side of your MP joint. It is typically torn in people that fall on an outstretched hand. It is sometimes called a "skier’s thumb" because a lot of skiers get this either when their ski pole gets caught around their thumb when they are falling or when they do a
Here’s an example of somebody with an ulnar collateral ligament tear. On this particular individual, the x-rays look pretty normal but when you get a stress view, you can see that here’s their thumb metacarpal, here’s their proximal phalanx. They’ve got about 40º of angulation here. This is a pretty clear indication of somebody with instability of their ulnar collateral ligament.
Another thing that sometimes you’ll see on an x-ray that gives you a warning that somebody’s had a significant ulnar collateral ligament injury, sometimes you’ll see this little avulsion fleck. This little piece of bone has been pulled off by the ulnar collateral ligament. So that’s another thing that you can look for.
Metacarpal fractures. Small finger metacarpal neck fractures are something that you will certainly see if you work in an Emergency Room. Many primary care physicians are faced with evaluating these. Typically these are what we call "boxer’s fractures" although boxers rarely get them. It’s actually brawlers that sort of get them – people who don’t really know how to punch.
The key thing to look for on physical examination is rotational deformity. Most of the time, these are flexed down a little bit. That is not of tremendous functional consequence as long as the amount of flexion deformity is under 30 or so degrees. What really becomes a functional problem is when somebody has rotational deformity. So what you have to do is you have to compare both of their hands. Have them try to make a fist as best as possible and see if the small finger crosses over the ring finger. If they do, that’s the type of fracture that needs to be reduced.
So you can accept up to about 30º of flexion deformity without very much of a functional consequence. I usually immobilize these people for a brief period of time – maybe about two to three weeks – and then start early range of motion when it’s not painful.
Here’s a typical radiograph of somebody with actually boxer’s fractures of both the ring and small finger metacarpal necks. On the lateral view, we’ve marked it out here. Keep in mind that the metacarpal has a little bit of curve to it so ordinarily there’s going to be maybe about 10º of flexion. So this person, in total, has about 25º or so of flexion in the small finger. That was not a big deal. We treated this closed and he did fine.
The one thing you want to warn your patients about, even if you accept the 30º or so of flexion, the one thing that they will have is a little bit of cosmetic deformity. They will lose some of the prominence of their knuckles when they make a fist and sometimes they will get a little bit of added fullness on the palm side of the hand. Again, it’s usually not of much functional significance but you want to warn the patient to tell them that no matter how it gets treated they will probably lose a little bit of prominence of their knuckle.
Metacarpal shaft fractures. Just some general principles on shaft fractures. The non-border fractures tend to be a little bit more stable, meaning your middle and ring finger metacarpal shafts, because the intermetacarpal ligaments which sort of connect the metacarpal heads help to suspend the affected injury. Again, just like with the boxer’s fractures you want to look for rotational deformity. The angulation in the shaft, you can’t accept quite as much in the shaft as you can at the metacarpal neck. You can probably only accept about 10º, maybe 20º, of angulation of the metacarpal shaft. You also want to look for shortening on your x-ray.
Most of these ones, especially the ones that are sort of the long oblique fractures, those are the ones that we typically treat closed with cast immobilization. The ones that are more transverse tend to be more unstable and more often require surgical treatment.
Here is a typical one that is ideal for treating closed. Again, here is this oblique fracture of the ring finger metacarpal shaft. Since it is a non-border digit the metacarpal head is being suspended by the intermetacarpal ligaments here. There is no rotational deformity. There is minimal shortening. Lots of surface area. Stable injury. Ideal to treat closed. Lateral view. You can see the fracture here. Minimum angulation. Maybe 5-10º. No big deal.
Just a quick review of some common fingertip injuries that you will see. What to do about subungual hematomas. A very common injury. Someone gets a crush injury to one of their fingers. Certainly if a person has a lot of discomfort, it’s very reasonable to decompress a subungual hematoma. There are a couple of different techniques you can use. Some people like to use those hand held battery powered cauteries and burn a little hole through the back of the nail plate. That’s a very reasonable technique. If you don’t have something like that available, it’s a little bit more uncomfortable, but you can use like a #16 or #18 gauge needle and just sort of drill a hole through the back of the nail plate. The nail plate really doesn’t have any nerve fibers in it, per se, so it’s actually not that big of a deal.
The other question is to whether or not the person has a significant nail bed laceration. Certainly if you read the orthopedic textbooks, they will say that if the person’s subungual hematoma is 50% or more of the surface of the nail, then that’s an indication to remove the nail plate and do a nail bed repair. My person feeling is that’s probably a little bit of overkill. That’s just my bias but I personally usually don’t remove somebody’s nail plate and do a nail bed repair unless the plate is already partially off. If somebody has a stable nail plate, usually you can just leave those in place.
If you have a nail plate that has sort of been partially torn off and you can see that the nail bed is lacerated underneath there, it is very reasonable to repair those in the Emergency Room. Typically, I use a relatively small suture like a #5-0 gut suture, something that will absorb on its own, and then what you want to do is try to save the nail plate and you can stick that underneath the eponychial fold. If you don’t, what sometimes happens is the eponychial fold will scar down to your nail bed and that can give you kind of a funky looking nail when it comes back. So I typically will clean off the nail, stick it back under the eponychial fold, knowing that it’s going to kind of flake off and fall off within a week or two, but that’s really all you need. It’s just a little bit of a stent underneath there to keep them separated during the first week or so.
Fingertip amputations, meaning just losing the very tip of your finger. Again, very common injuries. Usually someone is cutting vegetables and gets a little carried away and takes off the tip of their finger. The general rule is if somebody has an exposed area of under a square centimeter that will almost always fill in on its own just by doing simple dressing changes. It does not need any kind of fancy skin grafting or rotational flaps or anything like that. It may take awhile.
Sometimes if you have a large defect, it may take up to six weeks to completely fill in but if you are able to get these to heal in with dressing changes alone, you get an excellent cosmetic result with pretty reasonable sensation in that area of the fingertip. If you have more than a centimeter of loss, that may require some type of surgical manipulation to get it closed and that’s usually when you might want to refer it on.
Another very common injury that you will see if you do Emergency Room work is what we call the "fight bite" when somebody has punched someone else in the mouth. The one thing I want to warn you about is to not underestimate the seriousness of the injury. Unfortunately, these oftentimes come in late and that makes things a little bit more difficult. When you do your physical examination and you are trying to decide how deep the person’s tooth went into their hand, the thing you have to remember is that you have to examine their hand in the position that it was at the time of impact. So if you are examining someone with their hand flat, the tendon might be gliding away from the position that it was in at the time of impact and you might not see the entry point through the tendon. So make sure to flex the fingers down even if the person denies having gotten the injury in a fight.
I have a very low threshold to do a surgical debridement of the area just because if you look at all of these people, probably about two-thirds of these people with fight bites have some type of penetration into the actual MP joint. If you let one of these go and it becomes infected, the functional result after getting an infection inside your MP joint is really quite poor and I’ve seen some very bad results when these are treated late.
Here is just an illustration of why these can be tricky. Again, when the person is making a clenched fist, the skin, tendon, joint capsule and bone are all sort of lined up in a row. But when they bring their hand out into extension, the skin slides away, the tendon glides back and you can really sort of get this valve where you can’t even see into where the tooth went in.
Here is a little clinical examination. This is a guy that came in with a fight bite and on physical examination, a fairly innocuous looking injury – just this tiny little scratch over the dorsum of their MP joint. We got some x-rays. Don’t really see much. There’s just this little gray area which I thought was just a soft tissue shadow. But when we actually went in for surgical exploration, this divot here is actually a hole that was made into his proximal phalanx. So that little gray spot on that x-ray was actually a complete hole that was made by the front tooth of his sister’s boyfriend.
Another type of infection that I want to warn you about. This is one of those things that is a true hand surgery emergency which is an infection of the flexor tendon sheath. You don’t want to mistake this for a cellulitis. There are sort of four cardinal physical examination signs that you look for to make the diagnosis of a flexor tendon sheath infection. Sometimes people refer to these as Kanavel’s signs. They were described by Ian Kanavel back in the 1920s.
The first physical exam sign is fusiform swelling. The person’s finger swells up and looks like a gigantic sausage. Pretty unmistakable. Typically, they have severe tenderness along the flexor tendon sheath. Very uncomfortable to palpate along the volar side of the affected finger. They have tremendous pain with passive range of motion, particularly with extension. So you try to straighten that finger out, exquisitely painful. Then typically, due to the swelling and the pus that is on the inside of their flexor tendon, they tend to have the affected digit held in a slightly flexed posture.
So these are the four cardinal physical exam signs of a flexor tendon sheath infection. This should not be passed off as cellulitis. This needs surgical drainage in almost all cases and is a serious problem. If it is treated late, again, the functional result of a late treatment of one of these is horrible because of the fibrosis and scarring that you get around your flexor tendon. So these must be treated early and must be treated surgically.
A few words on lacerations. Lacerations over the dorsum of the hand are, again, very common things. One word of warning. I guess in terms of treatment of these injuries, it sort of depends on your own personal level of experience and how comfortable you are doing kind of semisurgical procedures in the Emergency Room. When I say that extensor tendon injuries can usually be treated in the Emergency Room, I mean if you are experienced in doing tendon work and if you’re familiar with the rehabilitation or if you’re working in concert with another orthopedic surgeon. If you don’t have a lot of experience working with tendons and doing surgical procedures then these probably should be referred on.
But for those of you who do, extensor tendon lacerations over the dorsum of the hand and over the IP joints can typically be handled in the ER. You want to make sure that you are not missing a deep penetrating injury into the joint. If there is one you have to make sure that you thoroughly irrigate out the joint so they don’t get a septic arthritis. A direct repair of the tendon is usually possible although you have to make sure that you can clearly see both ends of the tendon. Occasionally I’ve seen some of the residents grab hold of tendon sheath or just some sort of fascial subcutaneous tissue thinking it’s the tendon so you want to be careful about that.
Oftentimes, you’ll use like a #4-0 Prolene type suture. That’s usually what we use in these tendons. Then typically for the IP joints, meaning the PIP and DIP joints, you only have to splint the affected joint in extension. So a laceration over the PIP joint, it’s an open central slip injury, you just put the PIP joint out in full extension and you can let them bend at the DIP joint. The open mallet fingers, meaning open injuries over the DIP joint, you can sew those up and splint them like you would a mallet finger.
Lacerations over the dorsum of the hand, we discussed the physical examination that you need to do. The other things you need to be concerned about, remember that there are two extensor tendons for the index finger and two extensors for the small finger. For those, if you are able to find the ends of the tendon and get them sutured together, those you typically splint including the wrist with the wrist in extension to keep tension off of your repair.
Flexor tendons are a different story. Flexor tendons should never be done in the Emergency Room, especially in the area that we call Zone II, meaning the flexor tendon in the area within the flexor tendon sheath which I will show you in an illustration on the next slide.
Flexor tendon injuries. On physical examination, you want to make sure that you don’t miss any neurovascular injury. Remember the neurovascular bundles are right next to the flexor tendons on both sides and so typically if like a knife type of laceration is what cut the tendon, it’s probably going to come very close to the digital nerves and digital arteries. If it’s being referred on, which it should be, the wounds can be washed out, the skin can be tacked shut and the hand can be splinted. These flexor tendon lacerations should really be surgically treated as soon as possible, preferably within a few days. You can extend that out to a week but really, the sooner you can get to these surgically the better.
This is the area that we refer to as Zone II which is sort of the most troublesome area of flexor tendon surgery. It’s this area within the flexor tendon sheath in the hand and in the thumb. It’s in this area that the two tendons sort of ride on top of each other. The area is relatively hypovascular. The tendons don’t have a lot of good supply and they tend to get adherent to the flexor tendon sheath in this zone. So this is definitely a problem area and definitely should never be surgically repaired in the Emergency Room.
Here are the typical physical exam features of somebody with complete lacerations of the flexor digitorum sublimis and flexor digitorum profundus. This is the Zone II area of laceration and you can see ordinarily when you have your hand in a relaxed position, you have what we call the normal flexion cascade of your fingers. Even relaxed, your fingers are a little bit flexed from the normal tension on the flexor tendons. When those flexor tendons get cut, the extensor tendons overpower the fingers and those fingers fall into extension. So this is sort of the classic appearance of somebody that has had both their FDP and FDS cut.
If somebody has a normal flexion cascade, that’s not a guarantee that the flexor tendons are not injured because they might have just cut their flexor digitorum sublimis. In that case, the flexion cascade usually looks pretty normal.
A quick word on lacerations of the wrist. When you are evaluating someone with a slashing injury to the wrist, just remember that it’s truly a lesson in cross-sectional anatomy. The things that you need to be concerned about are the median and ulnar nerves and the radial and ulnar arteries.
Here’s a quick review of the cross-sectional anatomy of the wrist. This is the radius. This is the ulna. This is the pronator quadratus. This is the radial side of the wrist. This is the ulnar side of the wrist. Dorsum. Volar. If somebody has a laceration over the volar side of the wrist, for example, on a suicide attempt or something like that, it’s amazing how superficial the median nerve is. It’s basically sitting right underneath the palmaris longus and right underneath the flexor carpi radialis. So if you see somebody with a transverse laceration across the wrist, you have to do a very careful median nerve examination to make sure that they didn’t cut through their median nerve. Or if somebody has obvious flexor tendon lacerations, you can see that the median nerve is more superficial than those flexor tendons. So if somebody has a flexor tendon laceration, then almost certainly they’ve probably cut their median nerve as well. Likewise, if you detect that somebody has a flexor digitorum profundus laceration at the level of the wrist, then almost certainly they have to have gone through their sublimis and their median nerve as well.
Ulnar sided wrist laceration. If the person is cut near their flexor carpi ulnaris on this side of the wrist, just remember the ulnar artery, which is usually the dominant artery of the hand is right underneath there along with the ulnar nerve.