The end joint of the finger is called the "distal interphalangeal joint" (abbreviated as "DIPJ"). The finger joint that is closer to the knuckle is called the "proximal interphalangeal joint" (abbreviated as "PIPJ").
Proximal interphalangeal joint (PIPJ) dislocation
The most common ways to dislocate the PIPJ are in a sporting injury or fall. In most instances it is possible to relocate the joint without surgery. In hospital an X-ray is performed before and after the relocation, so that any fracture can be detected. After the finger is relocated it is common to see a tiny fracture (or small fuzzy area) at the front of the finger, which usually is a sign of a volar plate injury (also termed a "volar plate avulsion"). The volar plate is a ligament on the front of the finger that stops your fingers from bending over backwards.
A volar plate avulsion can be repaired surgically, but more commonly the ligament injury is managed with splinting and mobilisation. The splint prevents the finger from straightening fully, allowing the ligament to heal and for stability to be regained. Note that the finger is not splinted straight for weeks on end. It is equally important to flex the joint regularly, so that the range of movement is maintained. In the first few days the finger will usually be too sore and swollen to move much.
Sometimes a severe PIPJ dislocation will completely disrupt both the volar plate and the collateral ligaments. In this instance the joint will not look completely back in position on the second X-ray; this type of injury usually requires surgery.
An "open" dislocation occurs when the force of the dislocation tears the tissues overlying the joint, resulting in a wound that allows the joint to communicate with the outside world. This carries a significant risk of infection. Antibiotics and surgical washout of the joint are necessary. At the time of the washout the surgeon will commonly repair any injured ligaments. You will be placed in a splint and commence movement exercises around a week after surgery.
The most important goals in treating a dislocated finger are to end up with a mobile, stable finger. You want your finger to have a full range of movement and to not be unstable in any particular direction. Achieving this requires a careful balance of stillness (splinting) and movement (finger exercises), and sometimes (but not usually) surgery. Please call Melbourne Hand Surgery if you have any concerns!