Our hands often take the brunt of what the world throws at us – they are integral to how we sense, evaluate, manipulate, and use our surroundings. So it’s no surprise that falling onto an outstretched hand is a common occurrence – after all, if you’re going to fall, you’re probably going to stick your hand out to catch yourself. Most of the time, this results in nothing more than a sore wrist for a day or two. But sometimes, there’s more to it. The wrist has 15 bones and even more ligaments, working in a complex interplay to allow you to lift a heavy weight, play tennis, write a note, use sign language, or even perform surgery. A significant injury to any of these structures can result in stiffness, chronic pain, and decreased functionality of your hand and wrist. Common injuries of the wrist from a fall include fractures of the radius, ulna, and scaphoid, injuries of the scapholunate, lunotriquetral, and radiocarpal ligaments, and injuries of the triangular fibrocartilage complex. Today, I want to discuss scaphoid fractures and how best to have them evaluated and treated.
That’s a lot of bones in a small areaWhy are there so many wrist bones anyway?
Your knees seem pretty important, and there are just four bones involved in that joint. Your finger joints only have two bones each. So why does the wrist area need 15? The short answer is that the wrist does an incredibly variety of movements, unmatched by any of our other joints. It can move up and down (flexion and extension), side to side (ulnar and radial deviation), spin into palm down and palm up positions (pronation and supination), and combinations of all three of these motions. By contrast, the knee is like a simple door hinge – just moves back and forth in one direction. The more types of movements you have, the more complex the joint becomes, and the more bones and ligaments you need to keep the whole system strong and stable in any position. That’s how we end up with the sheer complexity of the wrist.
That bump is right over the scaphoid What makes the scaphoid special?
The scaphoid is unusual because it interacts with a lot of different bones in the wrist. It has joint connections (articulations) with five different bones. And when the wrist goes through its motions of flexion and extension and deviation, the scaphoid bone moves around a lot. Partly because it moves so much, and partly because it interacts with some many other bones, it is particularly vulnerable to injury. In addition, when it is injured, it can cause significant disruption of the wrist stability and motion – it is the lynchpin of the wrist in many ways, and links different parts of the wrist with each other. When it no longer works correctly, the entire wrist can have trouble remaining stable. Finally, the scaphoid has an unusual blood flow. Blood flow enters the bone in only a couple of areas that are closer to the hand than the wrist, and the rest of the bone relies on that blood slowly trickling backwards through the bone. So when the scaphoid breaks, the part of the bone closer to the wrist may be altogether cut off from its blood flow, making it hard to heal.
How do you evaluate a possible scaphoid injury?
The most important thing with a scaphoid injury is to treat it quickly. Delaying treatment by weeks and months may cause significant difficulty in healing the bone, and can even lead to the dreaded complication of nonunion – i.e. the bone is unable to heal altogether. To avoid this complication, it is very important to keep the scaphoid bone protected, and prevent it from moving. So if you have a fall, or a car wreck, or any other injury and your wrist hurts, it’s best to get it looked at by a doctor – at your primary care doctor’s office, or an urgent care, or an emergency room. Usually, an X ray will be performed, and you will be placed into a brace to protect the bones. Unfortunately scaphoid fractures are sneaky, and often don’t show up on that first X ray. So it is important to keep wearing the brace for about 2 weeks and get a second X ray at that time. If you have a scaphoid fracture, it will almost certainly be visible on an X ray by 2 weeks after the injury. At that point if there is no fracture, you’re in the clear (although if your wrist still hurts, it might mean you have a ligament injury, and you should have that looked at too!). If you do have a fracture however…
How do you treat scaphoid injuries?
Fractured scaphoids – like any fractured bone – are not all the same. So of course, the treatment varies as well. Most commonly, a fractured scaphoid can be treated with a cast. Because of the issues with blood flow that I mentioned earlier, scaphoid bones are slow to heal, and often have to be in a cast for 8 to 12 weeks. Certain types of scaphoid fractures require surgery, either because the bone fragments have moved too much and need to be reset, or because the bone is broken in an area where the risk of nonunion is very high without surgery. Other types of patients, like smokers, may need surgery because they have a reduced ability to heal, and so surgery is necessary to improve chances of bone healing. Finally, there are patients who just can’t be in a cast for 12 weeks, and surgery may be a good option for them too. For example, professional athletes will often have surgery for injuries like this, to minimize the number of games they have to miss.
Surgery to fix a scaphoid fracture is usually done by placing a screw in the bone. This is a special kind of screw called a headless compression screw. The screw is completely buried inside the bone, with no part of it sticking out of the bone. And it is designed in a clever way that allows the screw to actually squeeze the two pieces of the scaphoid bone together so that they are very solidly reattached. It is thought that this helps the blood flow from one piece of bone to the other piece and assists in healing. With surgery, patients will often only need a cast for 2 weeks, and can switch to a removable brace at that point, which is very convenient.
What happens if you accidentally ignore a scaphoid fracture – or if it doesn’t heal after casting?
The biggest risk of leaving a scaphoid fracture untreated is the problem of nonunion. This is where a broken bone refuses to heal and remains as two (or more) separate pieces of bone. In the case of the scaphoid, nonunion can lead to avascular necrosis. In avascular necrosis, part of the broken bone has no blood flow (it is avascular) and therefore it slowly withers away into nothing (necrosis). When this happens, the wrist starts to have a lot of problems – because one of the lynchpins of the joint hsa been damaged, the entire wrist joint starts to malfunction. The other wrist bones start to get out of position, and this leads to premature development of arthritis in multiple areas of the wrist. If the problem is caught early, the scaphoid can still be fixed. But fixing it at this point often requires a bone graft – i.e. taking bone from another part of your body to place it in the scaphoid and help it heal. If the problem goes on for long enough and arthritis has developed, fixing the scaphoid is no longer adequate, and far more complicated procedures have to be performed to reduce the chronic pain that has developed. But these complex procedures will often decrease the motion of the wrist and even decrease strength. So we really want to avoid them if possible.
So if your wrist hurts…
Don’t ignore the problem! Have it checked out within a few days to make sure it is not a scaphoid fracture. Ignoring a scaphoid fracture can turn a small, relatively easy-to-treat problem into a complicated problem that might result in chronic pain and stiffness of your wrist.
