These are probably the most frequent injury to the hand, generally resulting in the fracture of the head of the fifth metacarpal, image 1, or fractures of the shaft of one or more metacarpals, images 2 and 3. Image 3 is the same injury as image 2 but it can be seen that the fracture is not as apparent and indeed if the hand was rotated radially any more the fracture could be missed. This shows the importance of having the two accurate views. Also on image 3, look at the fifth metacarpal, on the radial border, an oblique lucency (darker line) can be seen projecting proximally from the cortex to the medulla. This is the nutrient foramen which can often be mistaken by the less experienced for a fracture. See also image 31 on this page.

Crush injuries to the tips of the fingers can result in comminuted fractures as in images 5 and 6. Again the P.A. view alone does not tell the whole story. Undisplaced versions of these injuries can be hard to diagnose and there are normal growth variants which look very similar to image 5 so be careful.

These are some of the most often missed fractures, probably due to the fact that the fragments can be very small. They tend to be associated with hyperflexion or hyperextension injuries and are where the tendons have been pulled, and partially or totally separated from the bony insertion, pulling a small piece of bone with them. Image 9 is a fairly obvious example but have a look at image 10. The avulsion here is at the base of the middle phalanx and is so small it could be easily missed. Do not forget that avulsions can be from the lateral aspects also, see image 11, and can also be quite large fragments, see image 12.

Dislocations are usually pretty straightforward as long as two views are available. Images 13, 14 and 15 are examples. Do remember however that severe dislocations are stretching the ligaments to their limits and can involve an avulsion fracture as well, see image 16. The middle phalanx has been displaced posteriorly leaving behind an avulsed fragment lying just anterior to the head of the proximal phalanx.

Dislocations can often involve larger more obvious fractures as in image 17. Image 18 is similar to image 17 but includes a flake fracture of the trapezium and in this example the carpo-metacarpal joint is only subluxed.

One less common example is image 19 which could be easily missed by the less experienced. This is a punch injury which resulted in a dislocation of the fifth carpo-metacarpal joint, and it can be seen that the base of the fifth metacarpal is lying posterior to the carpals.

Enchondromas are fairly common, and are benign, expansive, thin walled bone tumors. See image 20. Due to the weakness of the bone wall they are often the site of a fracture. These pathological appearances should really have a radiologist's opinion just in case it is not an enchondroma. Some pathological fractures can be subtle however, and therefore a report which highlighted the fracture through an area of unknown pathology, but also suggested a radiological opinion, would be a very good idea.

Foreign bodies are quite frequent in the hand and occasionally involve the bone as in images 21 and 22. It can be seen in image 22 that the fish hook has caused a fracture in the phalanx which is not visible in the lateral view.

It is important that any bony involvement is diagnosed as this is basically a compound fracture where infection can enter the bone. The management of the patient may change if there is bony involvement. Image 23 shows a nail from a nail gun penetrating the wrist. Has the nail penetrated any bone? To exclude bony involvement a radiograph must be produced with the central ray passing along the long axis of the foreign body so as to project it as a dot on the radiograph, as in image 24. If the dot appears outside any bone then you can be sure there was no penetration of the bone. It does not matter what the position is as long as the central ray passes along the long axis. If the foreign body is not linear then you should do your best to achieve a similar result with the part that is closest to the bone.

Be careful with F.B. films as there are many artifacts which can trip the reporter up. One of these is the skin flap as in image 25. It can be seen at the lower end of the laceration that there appears to be a linear F.B., possibly glass in appearance. This is in fact the skin flap with congealed blood, seen end on.

An occasionally seen growth variant is the ivory epiphysis as in image 26. This may be linked to general growth retardation and is just an increase in the bone density.

Image 27 shows a small longitudinal lucency centrally at the tip of the terminal phalanx. This was actually picked up after the finger was shut in a car door. However, as there appears to be no disruption in the trabeculae or the cortex, this is more likely to be a remnant of a bifid terminal phalanx which occurs in early growth.

These lucencies can be quite round in appearance, as in image 28 which is almost certainly a remnant of a bifid or cleft epiphysis, a cyst is probably excluded as the "hole" did not appear in other projections. These could be confusing if they present after a drilling injury, always check for cortication.

Image 31 shows what appears to be a normal nutrient foramen in a proximal phalanx of the hand which is in fact a saw cut, a small fragment of bone can be seen adjacent to the proximal part of the cut. Image 32 shows the second projection and the cut can just be seen crossing the bone. It can be seen that care must be taken with nutrient foramina.