Is DIP dislocation common? Which sports tend to cause it?

A pure DIP dislocation is not common; it usually comes with a fracture or tendon tear, and it is less frequent than proximal interphalangeal (PIP) joint dislocation. It is most common in sports such as basketball, football, softball, and baseball, and most cases are dorsal dislocations.

What symptoms does a DIP dislocation cause?

The finger is painful with limited motion, and there may be an obvious deformity. Some patients reduce the joint themselves on the field or before seeing a doctor, so the dislocation may not be visible at the time of the visit.

What does the physical examination assess?

The physician palpates along the joint line to find the point of maximal tenderness, checks for a possible fracture or dislocation, and tests the flexor digitorum profundus and terminal extensor function, collateral ligament stability, and the volar plate with the PIP joint in extension. The skin is also checked for an open injury, along with the neurovascular status.

What injuries should a DIP dislocation be distinguished from?

The differential diagnosis includes a distal or middle phalanx fracture, flexor digitorum profundus rupture (Jersey finger), extensor mechanism rupture (Mallet finger), bony Mallet finger, fracture-dislocation, collateral ligament rupture, and chronic instability.

What tests are needed to make the diagnosis?

Anteroposterior, lateral, and oblique X-ray views are recommended to assess the situation before and after reduction and to look for any bony avulsion of the volar plate. Ultrasound can confirm the degree of injury to soft tissues such as the collateral ligaments and tendons.

Finger Impact Injuries: What You Need to Know About DIP Joint Dislocation

The finger has a proximal joint, the proximal interphalangeal (PIP) joint, and a distal interphalangeal (DIP) joint. The PIP joint is the most commonly injured site in sports; its hinge motion allows flexion and extension from about 0 degrees to 110 degrees. The DIP joint works much like the PIP joint but has a smaller range of motion, with flexion of roughly 0 degrees to 80 degrees.

Dislocation of the finger’s distal interphalangeal (DIP) joint or the first interphalangeal (IP) joint most often occurs through a hyperextension injury of the DIP joint, known as a jammed finger.

Epidemiology

A pure DIP dislocation is not common and usually comes with a fracture or tendon tear.
Compared with proximal interphalangeal (PIP) joint dislocation, DIP dislocation is less frequent.
Most dislocations are dorsal dislocations, especially when they happen during sports, and they can cause injury to the volar plate within the joint.
It is most common in basketball, football, softball, and baseball.
Volar dislocations are usually related to a crush or twisting injury and can cause rupture at the insertion of the terminal extensor tendon, making them harder to manage.
Simultaneous DIP and PIP dislocation is rare but is seen more often in the ring and little fingers.

History

The finger is painful with limited range of motion.
There may be an obvious deformity.
The patient may have reduced the joint on the field or before seeking care.

Physical examination

Gently palpate the joint along the joint line to assess the point of maximal tenderness and to check for possible bone fragments or dislocation. A movable lump or swelling near the joint may indicate a tendon or ligament tear.
With an unreduced dislocation, there may be an obvious deformity: in a dorsal dislocation the distal phalanx sits above the plane, and in a volar dislocation it sits below the plane.
During the examination, note the following:
With the PIP joint held in extension, test the flexor digitorum profundus (FDP), terminal extensor function, and sensation at the fingertip.
Test collateral ligament stability: using 10 degrees as the reference, laxity beyond this value indicates collateral ligament injury.
Check the volar plate: hyperextension of the joint may indicate volar plate injury.
Assess the skin for an open injury, which is usually seen on the palmar surface.
Assess the neurovascular status.

Injury grading includes:

Grade I: a small tear of the ligament, with a stable joint (bone is unlikely to displace).
Grade II: a partial tear of the ligament, with the joint showing slight instability (the bone may displace).
Grade III: a complete tear of the ligament, with the joint showing major instability (the bone may displace).

Differential diagnosis

Distal or middle phalanx fracture (such as a terminal fracture).
FDP rupture (such as Jersey finger).
Extensor mechanism rupture (such as Mallet finger).
Bony Mallet finger (a bony avulsion of the extensor mechanism at the dorsal base of the distal phalanx).
Fracture-dislocation.
Collateral ligament rupture.
Chronic instability.

Diagnostic tools

X-ray: three views (anteroposterior, lateral, and oblique) are recommended to assess the situation before and after reduction, with special attention to any bony avulsion of the volar plate.
Ultrasound: can confirm the degree of injury to soft-tissue structures including the collateral ligaments and tendons.

General measures

Reduction:
Reduction can be performed immediately on the field to relieve pain, and it is usually relatively easy.
Reduce using firm traction and steady longitudinal traction.
Slight hyperextension with volar pressure applied to the distal phalanx may help with reduction.

Post-reduction assessment

After reduction, carefully check function and any skin injury.
Perform an X-ray to confirm joint congruity.

Immobilization and rehabilitation

For a dorsal dislocation, after reduction the joint should be splinted in about 20 degrees of slight flexion for 1 to 2 weeks.
A volar dislocation is managed like a Mallet finger, with the DIP joint splinted in extension for up to 8 weeks to let the tendon heal.
Longer immobilization increases the chance of joint stiffness.
Once joint stability and range of motion (ROM) are acceptable, the patient can return to sport.
Weekly follow-up after reduction is recommended to confirm finger joint stability and correct position.
If long-term immobilization is needed, regularly check the skin under the splint as well as the neurovascular supply.

Surgery

Surgery is indicated in the following situations:
- A combined fracture or fracture-dislocation with insufficient joint stability.
- Ligament rupture or complete injury to the volar plate.
- Chronic instability after failed conservative treatment.
- An emergency such as poor blood flow to the finger or an open dislocation.
- A fracture involving more than 40 percent of the joint surface.
Common procedures include volar plate repair, ligament repair, or fixation of an intra-articular bone fragment.

Long-term follow-up

After the splint is removed, progressively increase activity, including:
- Range of motion (ROM) recovery training.
- Strength training to improve grip strength and finger flexion and extension.
The goal is to restore hand function and reduce chronic pain or stiffness.

Prognosis

The prognosis is good, especially for patients reduced early and splinted appropriately.
Minor volar plate injury or a simple dislocation usually does not affect long-term function.
Without timely treatment or stable reduction, chronic pain, instability, or joint stiffness may result.

References

https://www.acep.org/sportsmedicine/newsroom/newsroom-articles/august2022/the-jammed-finger
https://www.orthobullets.com/hand/6038/phalanx-dislocations
Sports Health. 2016 Jul 15;8(5):469–478.