A mallet finger is an injury that affects the end joint or distal interphalangeal joint (DIP joint) of your finger. It often occurs while playing ball sports, however, can occur during any activity where the tip of the finger is forcefully flexed causing stress on the tendon that straightens the tip of the finger (extensor tendon). If you have sustained a mallet finger injury, you will not be able to straighten the tip of the finger with your muscles and it will droop in towards your palm.
Tendons are soft tissue structures that attach muscles to bone. The tendon that straightens the tip of our fingers is called the terminal extensor tendon. The muscle belly for this tendon sits in the back of our forearm and the tendon attaches to the base of the end bone in our fingers (the distal phalanx). Mallet finger injuries can occur with forced hyperflexion of the tip of the finger, however, can also be caused by lacerations. There are two categories of mallet finger injuries:
Extensor tendon rupture: The extensor tendon snaps apart (or ruptures) due to force.
Avulsion fracture: A fracture to the piece of bone where the extensor tendon attaches which results in the tendon no longer being attached to the bone.
The main indication of having sustained a mallet finger injury is that the tip of the finger can’t straighten and droops towards the palm. The injured finger is often painful and swollen and can also be bruised.
Usually, an x-ray will be requested to determine if the mallet injury is an extensor tendon rupture or an avulsion fracture. Depending on the nature and severity of the injury, mallet fingers can be treated conservatively or surgically.
Conservative (non-surgical) treatment:
Fortunately, most mallet finger injuries can be treated conservatively. Your therapist will make a custom-made thermoplastic splint to keep the tip of your finger straight, or slightly hyperextended while allowing the middle joint to move. You must wear the splint full time for 6-8 weeks – 24 hours a day continuously – including showering and sleeping. If the tip of the finger bends at any point during these weeks, then the healing process must start again which prolongs therapy and a return to your usual activities.
After 6-8 weeks of continuous full-time splinting, the splint will be removed and your therapist will assess the positioning of the injured finger. If it is still slightly bent, the splint may be worn full time for a further 2 weeks. If the finger is staying straight, a limited exercise program will be recommended, however, you will continue to wear the splint most of the time otherwise.
From 6-8 weeks until 12 weeks post splinting, your therapist will guide you on continued splint weaning and progress your exercise program. It is not expected that the tendon or bone will be strong enough to return to contact/ball sports until 12 weeks post splinting.
At 12 weeks post splinting, some patients may have a very slight bend in the tip of the finger or they may notice a small bump at the back of the finger, however, this normally doesn’t cause any functional limitations and is generally cosmetic.
If the bone fragment is large enough, or there is a laceration where the skin and tendon are cut, surgery may be required. Your GP or therapist can arrange an appointment with a surgeon as required. There are a variety of surgical techniques that can be performed to treat mallet injuries depending on the nature of the injury and the time since the injury. Your surgeon will assess your injury and discuss these options with you.
Following surgery, a custom-made splint will be fabricated to keep the tip of the finger straight while the tendon/bone and the wound heals. The splint will generally be worn full-time for 6 weeks and your therapist will then give you exercises to gradually get the finger moving and slowly wean you out of the splint.
If you don’t get your mallet finger injury treated it often results in stiffness and an ongoing bend in the tip of the finger. No treatment or delayed treatment can also result in a deformity to the finger called a swan neck. This involves hyperextension of the middle knuckle and flexion of the end knuckle and can result in pain and functional difficulties. It is best to get your injury treated as soon as possible to reduce the risk of further deformity or functional limitations and get you back to your meaningful activities as soon as possible.
The team at Melbourne Hand Therapy are specialists in the treatment of mallet finger injuries.