A mallet finger is a deformity of the fingertip resulting in an inability to fully extend, or straighten, the digit. It can result from a forceful trauma to the fingertip, such as being impacted by a ball (“baseball finger”), or following minor trauma such as tucking in a bed sheet. A cut to the back of the finger may also cause a disruption of the extensor tendon.
The diagnosis is usually evident by the position of the fingertip. In addition to a fingertip that droops down, mallet finger injuries can result in pain, swelling, and bruising around the fingertip. X-rays are recommended to look for an associated fracture and stability of the joint. When only the tendon tears off of the bone, it is referred to as a “soft tissue” mallet finger. Occasionally, a piece of bone tears off with the tendon, referred to as a “bony” mallet finger.
For most mallet fingers, treatment typically consists of splinting the fingertip in extension (completely straight) full-time for 8 weeks (see image below). Splint compliance is extremely important for optimal results – the splint must be worn 24 hours/day for the tendon to heal correctly back to the bone. Splints can be changed after bathing, but the fingertip should be held extended by pressing it onto a flat surface during splint changes or by holding the fingertip extended by the nail. Any disruption in splinting can cause the tendon to re-tear off the bone, and require a longer period of immobilization or permanent drooping. After the initial full-time splint period of 8 weeks, the splint is usually worn at nighttime for an additional 4 weeks. Afterward splinting, some stiffness or residual drooping of the joint may be present, and therapy may be indicated.
If x-rays show that large fragment of bone pulled off with the tendon resulting in a joint surface that is uneven or partially dislocated (subluxated), surgery may be recommended to minimize pain, stiffness and the risk of developing arthritis in the finger. Chronic soft tissue mallet fingers that were not treated early or successfully may occasionally be surgically treated by tendon repair or re-tensioning.