Mallet finger is a relatively common injury to the end joint (distal inter-phalangeal (DIP) joint) of a finger. It results in damage to the extensor (straightening) tendon of the finger. It can occur following an acute hyperextension of the joint frequently in contact sports but often the activity can be apparently innocuous, such as making the bed. Iif the finger is cut at this point then it can transect the tendon. Sometimes the injury casues a small fragment of bone to be avulsed (pulled off).
Characteristically the end joint droops and it cannot be actively straightened. It can be surprisingly painful and the joint can become very red and swollen. The flexor (gripping) tendons are much stronger than the extensors, so the finger will always droop. However the big difference between the two types of tendon is that if the flexor tendon is damaged then, because it is under a lot more tension, the ends will fly apart, whereas the extensor tendon ends tend to stay close together. Treatment is very simple - the finger needs to be put into a simple splint which will keep the end joint straight. This will bring the two damaged ends virtually together. The drawback is that it takes six weeks for the tendon healing to be strong enough to start coming out of the splint. This is very frustrating, but if the finger is allowed to droop during that period then the tendon repair will be pulled apart and you go back to 'square one'. Thus it is essential that the end joint is kept absolutely straight for the whole 6 weeks. If you cheat you will only have to start the 6 weeks again! You can remove the splint for cleaning purposes but only if you keep the finger absolutely straight.
These splints come in different sizes and it is important that they are fitted properly. It is essential that the splint does not stop you moving the next joint along towards the hand (the PIP joint). It is possible that you may need to have a smaller size fitted after the swelling goes down. After the 6 weeks, the splint can be removed and the tendon healing assessed. If all is well then you can wean yourself out of the splint during the day but continue to use it at night over a the next 2 week period.
Even if there is a delay over several weeks or months, splintage is still recommended. Very occasionally there may be an indication for surgery, to repair the tendon. Unfortunately it means internally splinting the joint by passing a stainless steel wire across the two end bones of the finger. This wire would have to stay in for between 6 to 8 weeks before it is removed. It is even more inconvenient than the splint and carries a significant risk of infection.