Mallet Finger (Extensor Tendon Injury)

A **mallet finger**, often referred to as "baseball finger," is a common upper extremity trauma injury that occurs when the terminal extensor tendon—the tendon responsible for straightening the furthest joint of the digit—is damaged or torn. This injury isolates the distal interphalangeal (DIP) joint, leaving the patient unable to actively extend or lift the tip of the finger, causing it to droop permanently in a flexed position.

At Erlanger Hayes Hand Center, our orthopedic specialists perform meticulous evaluations of extensor tendon disruptions. Whether the injury is a pure tendon tear or an avulsion fracture (where the tendon pulls away a small fragment of bone), proper early intervention is critical to achieving full mechanical restoration and avoiding permanent stiffness.

Primary Causes and Pathomechanics

Mallet finger injuries typically occur when an unyielding, hard object strikes the very tip of an extended finger, forcing it to bend sharply while the extensor muscle is actively trying to keep it straight. Common mechanical causes include:

• Sports Collisions: A baseball, softball, basketball, or football striking the extended fingertip during a catch or play.
• Minor Daily Accidents: Forceful jamming of the finger while performing routine manual tasks, such as tucking in bed sheets, pulling up socks, or catching a falling object.
• Workplace Exertion: Direct sudden trauma or heavy crush forces experienced by laborers, technicians, or manufacturing workers.

Clinical Symptoms

The signs of a terminal extensor tendon injury are highly localized and visually evident immediately after the trauma:

• Fingertip Droop: The tip of the affected finger rests at a downward angle and cannot be straightened actively by the patient. However, the finger can easily be pushed straight passively with the other hand.
• Localized Pain & Tenderness: Acute pain and swelling over the dorsal side of the DIP joint (around the base of the fingernail).
• Subungual Hematoma: Bruising or blood collecting underneath the fingernail, which often indicates an underlying avulsion fracture of the distal phalanx.

Diagnostic Imaging

To accurately assess the structural damage, our physicians perform digital X-rays of the affected digit. Imaging is necessary to determine if the injury is a **tendinous mallet** (a pure tear of the soft tissue tendon) or a **bony mallet** (where an avulsion fracture has occurred). The X-ray also allows the hand surgeon to evaluate the exact percentage of the joint surface involved and rule out any partial dislocation (subluxation) of the joint, which would alter the treatment path.

Advanced Treatment Frameworks

The main clinical objective is to hold the terminal extensor tendon in a shortened, extended position so that the torn ends can knit back together securely over time.

1. Non-Surgical Custom Splinting Protocols

The vast majority of mallet finger injuries can be successfully treated without surgery through strict adherence to an immobilization protocol overseen by our **certified hand therapists (CHTs)**:

• Continuous Custom Splinting: The DIP joint is placed in a custom-molded thermoplastic splint that holds the joint in slight hyperextension. The middle joint of the finger (PIP joint) is left entirely free so the patient can maintain hand mobility.
• Protocol Duration: The splint must be worn continuously for 6 to 8 weeks for a pure tendon tear, and usually 6 weeks if it is a stable bone fracture.
• Weaning & Rehabilitation Phase: Once the surgeon confirms the tendon has clinically healed, the patient transitions to wearing the splint only at night or during strenuous tasks for an additional 3 to 4 weeks. CHTs then guide gentle exercises to safely rebuild flexibility and grip power.

2. Surgical Fixation and Management

Surgical intervention is considered only under specific, unstable clinical conditions. If the initial X-ray reveals a large avulsion fracture fragment that involves more than one-third of the joint surface, or if the joint has shifted out of alignment (subluxation), surgery becomes necessary.

During this minor outpatient procedure, the hand surgeon uses minimally invasive techniques to realign the bone fragment and splint the joint internally. This is typically achieved by placing a temporary surgical pin (K-wire) longitudinally across the DIP joint to hold it perfectly straight. The pin remains securely in place for approximately 6 weeks and is comfortably removed in the office once bone and tendon continuity are restored, followed by a dedicated physical therapy path.