Mallet Finger & Extensor Tendon Injuries

What Are Extensor Tendon Injuries?

Extensor tendons run along the back of your hand and fingers, just under the skin. They connect muscles in your forearm to the bones in your fingers and allow you to straighten your fingers and thumb. Because these tendons lie so close to the surface with little protection, they can be injured by minor cuts or jamming impacts that may seem insignificant at first.

Mallet finger is the most common extensor tendon injury. It happens when the tendon that straightens the tip of your finger tears away from the bone or gets cut. This can occur when something strikes the tip of your finger, like a ball during sports, or when you jam your finger closing a door or tucking in sheets. The force causes the fingertip to bend suddenly, tearing the tendon from its attachment. Sometimes a small piece of bone pulls away with the tendon. Without this tendon working properly, the fingertip droops and cannot straighten on its own.

Symptoms

The most obvious sign of mallet finger is a drooping fingertip that you cannot straighten, no matter how hard you try. The finger is often mistaken for being jammed. You may notice pain, swelling, and bruising around the injured joint. Sometimes blood collects beneath the fingernail, causing additional pain and pressure. The nail can become partially or completely detached from the skin fold at its base.

With other extensor tendon injuries on the back of the hand or fingers, you'll have difficulty straightening one or more fingers or your thumb. A cut on the back of the hand may not look serious, but if you notice any trouble extending your fingers afterward, the tendon may be damaged. Boutonniere deformity is another pattern of extensor tendon injury where the middle joint of the finger bends down and won't straighten, while the fingertip bends backward.

Causes & Risk Factors

Mallet finger most commonly occurs during sports when a ball or other object strikes the tip of an extended finger. Basketball, baseball, volleyball, and football are frequent culprits. It can also happen during everyday activities like making a bed, getting dressed, or catching yourself during a fall. The injury occurs when the fingertip is forcefully bent while the extensor tendon is trying to hold it straight, causing the tendon to tear or the bone to fracture at the attachment site.

Other extensor tendon injuries usually result from cuts on the back of the hand or fingers. Even small lacerations can sever these thin tendons because they lie so close to the surface. Kitchen knives, broken glass, power tools, and sharp edges on metal or wood are common causes. Sometimes chronic inflammation from conditions like rheumatoid arthritis can weaken and rupture these tendons without any trauma.

Anyone can experience these injuries, though they're more common in people who play ball sports or work with their hands. Children can injure the growth plate at the fingertip along with the tendon, which requires careful evaluation to prevent deformity as the finger grows.

Diagnosis

Medical attention should be sought promptly after these injuries, ideally within the first few days. Your hand surgeon will examine your finger and test whether you can straighten it actively. With mallet finger, you can often passively push the fingertip straight, but it immediately droops again when you let go. The location and nature of any cuts will be assessed.

X-rays are important to see if a piece of bone has fractured away with the tendon and to ensure the joint is properly aligned. Even injuries with only mild swelling may involve a fracture. If there's a cut, your surgeon will examine the wound to determine if the tendon has been severed. Blood under the nail or nail detachment may indicate additional injury to the nail bed or bone that needs attention.

Treatment Options

Most mallet finger injuries can be treated successfully without surgery through splinting. The key is keeping the fingertip straight continuously for about eight weeks while the tendon heals back to the bone. A special splint holds just the tip joint straight while allowing the middle joint to bend normally. This prevents stiffness in the rest of the finger while the injured area heals.

After the initial eight weeks, you'll gradually reduce splint use over another three to four weeks, typically wearing it only at night and during risky activities. Your surgeon will teach you how to care for the splint and your finger, and provide exercises to maintain motion in the joints that aren't injured. The fingertip must not be allowed to droop at any point during this healing period, or the clock resets and you need to start the splinting process over.

Surgery may be necessary if there's a large fracture involving the joint, if the joint is misaligned, or if splinting isn't successful or practical for your situation. Surgical options include placing a temporary pin through the joint to hold it straight, repairing the tendon with stitches, or using small screws to fix a fracture. For extensor tendon cuts, surgery is usually required to sew the tendon ends back together.

Other extensor tendon injuries along the back of the hand or fingers typically heal well with splinting if caught early. Splints must be worn continuously for eight to twelve weeks while the tendon repairs itself. If the tendon is cut, surgery to repair it is usually needed, followed by careful splinting and hand therapy.

Surgery: What to Expect

When surgery is needed, it's performed as an outpatient procedure under local anesthesia, with sedation available for select cases if needed. For mallet finger with a fracture, surgery involves realigning the bones and holding them in place with pins or small screws. The procedure typically takes 30 to 45 minutes.

For tendon lacerations, the surgeon cleans the wound and sews the torn tendon ends back together using special techniques that allow some early motion while protecting the repair. If scar tissue from an old injury is limiting motion, surgery can sometimes release the scar tissue and improve function, though results are better when injuries are treated promptly.

After surgery, your hand will be placed in a splint or cast to protect the repair. The position of the splint and how long you wear it depends on which tendon was injured and how it was repaired. Following your surgeon's instructions carefully is critical for success.

Recovery

Recovery requires patience and compliance with splinting instructions. With mallet finger treated by splinting, most people regain good function, though a slight droop or small bump at the back of the fingertip is common and rarely causes problems with daily activities. The fingertip usually regains most of its motion, and you can return to normal activities once the splint is discontinued.

After surgery or for more complex tendon injuries, hand therapy is often recommended. You'll receive a home exercise program with specific exercises to regain motion and strength while protecting the healing tendon. The therapist teaches you which movements are safe and monitors your progress. Most people can manage their recovery with these home exercises, though formal therapy sessions may be needed if you develop stiffness or have trouble following the program.

Full recovery typically takes three to four months, though you may return to many activities sooner with protection. Tendons heal slowly, and it's important not to rush the process. Following the splinting schedule and exercise program carefully gives you the best chance for a good outcome. Some stiffness is common after these injuries, but most people regain enough motion and strength to perform their normal activities without difficulty.

When to See a Specialist

If you have a drooping fingertip, a cut on the back of your hand or finger with difficulty straightening it, or any finger that won't extend properly after an injury, seek evaluation promptly. Early treatment leads to better outcomes. Even if the injury seems minor, damage to these important tendons can result in permanent deformity and loss of function if not addressed properly.

Dr. Lackey specializes in treating extensor tendon injuries, mallet finger, and other acute hand injuries. An evaluation can determine the extent of your injury and establish the right treatment plan to restore function and prevent long-term problems.