Mallet Finger: Causes, Symptoms & Splint Treatment

What Is Mallet Finger?

Mallet finger is an injury to the extensor tendon at the end of the finger that causes the fingertip to droop and prevents you from straightening it. The tendon either tears or pulls a small piece of bone away from the finger, disrupting the connection that allows you to extend your fingertip.

Mallet finger, also known as "baseball finger" or "drop finger," is one of the most common tendon injuries affecting the hand. The condition gets its name from the characteristic drooping appearance of the affected fingertip, which resembles a mallet or hammer. This injury specifically affects the distal interphalangeal (DIP) joint – the joint closest to the fingernail.

The extensor tendon runs along the back of the finger and is responsible for straightening the fingertip. When this tendon is damaged, the delicate balance of forces that controls finger movement is disrupted. The finger's flexor tendons (which bend the finger) continue working normally, but without the opposing force of the extensor tendon, the fingertip remains in a bent position. Understanding this mechanism is essential because it explains why continuous splinting is so important for healing.

There are two main types of mallet finger injuries that healthcare providers distinguish between when planning treatment. The first type is a purely tendinous injury, where the tendon itself tears or ruptures without involving the bone. The second type is a bony mallet finger, where the tendon remains intact but pulls away a fragment of bone from the distal phalanx (the bone at the fingertip). This avulsion fracture can range from a small chip to a larger fragment involving a significant portion of the joint surface.

Anatomy of the Extensor Mechanism

To understand mallet finger, it helps to know how the finger's extensor mechanism works. The extensor tendon travels along the back of the finger and splits into three slips near the middle joint (PIP joint). The central slip attaches to the middle phalanx, while the two lateral bands rejoin and attach to the distal phalanx. This terminal insertion is exactly where mallet finger injuries occur.

The extensor tendon is quite thin at its insertion point – only about 1-2 millimeters thick. This makes it vulnerable to injury from relatively minor trauma. Unlike the thick, powerful flexor tendons on the palm side of the finger, the extensor tendon at the fingertip has minimal structural reserve. Even a small disruption can completely prevent extension of the DIP joint.

Who Gets Mallet Finger?

Mallet finger can affect anyone, but certain patterns are commonly observed. The injury occurs most frequently in the dominant hand, which makes sense given that this hand is used more actively in sports and daily activities. Among the fingers, the middle, ring, and little fingers are most commonly affected, while the thumb is rarely involved due to its different anatomy.

Athletes are at higher risk, particularly those involved in ball sports such as basketball, volleyball, baseball, and cricket. The classic mechanism involves a ball striking the extended fingertip. However, mallet finger is not exclusively a sports injury. Many cases occur during everyday activities such as making beds, tucking in sheets, or reaching into tight spaces. Workplace injuries, particularly in manual labor occupations, also account for a significant proportion of cases.

What Are the Symptoms of Mallet Finger?

The main symptoms of mallet finger include a fingertip that droops downward and cannot be straightened, pain at the back of the fingertip near the nail, swelling at the DIP joint, and tenderness when pressing over the injured area. The finger can still be straightened passively by using your other hand.

The most obvious and characteristic symptom of mallet finger is the drooping fingertip. When you try to straighten your finger, the DIP joint remains bent while the rest of the finger extends normally. This creates a distinctive appearance where the last joint of the finger hangs down at an angle, typically ranging from 20 to 60 degrees. The droop is often immediately noticeable and can be quite dramatic in some cases.

Pain is present in most mallet finger injuries, though the intensity can vary considerably. Some patients report significant pain at the time of injury, often described as a sudden, sharp sensation at the back of the fingertip. Others may not experience severe pain initially, especially if the adrenaline from sports or activity masks the discomfort. Over the following hours and days, a dull, aching pain typically develops around the DIP joint.

Swelling is another common symptom, usually localized to the area around the DIP joint. The swelling may develop immediately after the injury or gradually over the first few days. In some cases, bruising may also appear, extending along the back of the fingertip or around the nail. The combination of swelling and pain can make the finger feel stiff and uncomfortable.

Passive vs. Active Extension

An important distinguishing feature of mallet finger is the difference between passive and active extension. While you cannot straighten the fingertip using your own muscle power (active extension), you can use your other hand to push the fingertip into a straight position (passive extension). This demonstrates that the joint itself is not damaged or blocked – only the tendon mechanism that powers the movement is affected.

This characteristic is important for diagnosis and has implications for treatment. If passive extension is also limited or impossible, there may be joint damage, scarring, or another condition that requires different management. Healthcare providers will always test both active and passive extension when evaluating a potential mallet finger injury.

When Symptoms Appear

In most cases, symptoms of mallet finger appear immediately after the injury. The fingertip drops and won't straighten from the moment the injury occurs. However, some patients may not notice the problem right away, particularly if swelling or pain distracts them from the functional deficit. Occasionally, patients present days or even weeks after the initial injury, having initially dismissed the drooping as temporary.

What Causes Mallet Finger?

Mallet finger is caused by forceful flexion of an extended fingertip, which tears the extensor tendon or avulses a bone fragment. Common causes include balls striking the fingertip during sports, fingers catching on objects like bedding or clothing, falls onto an outstretched hand, and crush injuries from doors or machinery.

The underlying mechanism of mallet finger is always the same: a sudden, forceful flexion (bending) of the fingertip while the extensor tendon is under tension trying to keep the finger straight. This creates a tearing force at the tendon's insertion point that exceeds the tissue's strength. The specific circumstances that create this force can vary widely, from high-energy sports injuries to seemingly minor everyday accidents.

Ball sports represent one of the most common causes of mallet finger. In basketball, volleyball, and baseball, players frequently have their fingertips struck by balls traveling at significant speed. The classic scenario involves catching or blocking a ball when the finger is extended – the ball's impact forces the fingertip to bend suddenly against the resistance of the taut extensor tendon. Football, rugby, and cricket also carry risk, as do any sports involving ball handling.

Household and occupational activities account for many mallet finger injuries that occur outside of sports. Making beds is a surprisingly common cause – fingers can catch in sheets and blankets, creating the sudden flexion force needed to damage the tendon. Tucking in bedding, reaching behind furniture, or grabbing objects in tight spaces can all result in mallet finger if the fingertip is forced to bend unexpectedly. These injuries often surprise patients because the precipitating event seems so minor.

Mechanisms of Tendon Damage

When mallet finger occurs, the extensor tendon can fail in several ways. In purely soft tissue injuries (about 60% of cases), the tendon itself ruptures. This can happen through the substance of the tendon or at its insertion onto the bone. The tendon tissue may be weakened by degenerative changes in older patients, making it more susceptible to injury from relatively minor trauma.

In bony mallet finger (about 40% of cases), the tendon remains intact but pulls away a fragment of bone from the base of the distal phalanx. This avulsion fracture occurs because the bone-tendon junction is the weakest point in some individuals. The size of the bone fragment can vary considerably – from a tiny flake to a large piece involving more than one-third of the joint surface. Larger fragments may cause joint instability and often require more careful management.

Risk Factors

Several factors can increase the risk of mallet finger or influence the injury pattern. Age plays a role, with middle-aged and older adults more likely to sustain tendinous injuries due to degenerative changes in the tendon. Younger patients are more likely to have bony avulsion injuries because their tendons are relatively stronger than their growing bone. Previous finger injuries, arthritis, and certain inflammatory conditions may also increase susceptibility.

Occupational factors are important – workers in manual trades, particularly those handling heavy materials or working with their hands in confined spaces, face increased risk. Certain hobbies, such as gardening or DIY projects, can also predispose to mallet finger injuries when hands are repeatedly placed in vulnerable positions.

When Should You See a Doctor for Mallet Finger?

You should seek medical care promptly if your fingertip droops and won't straighten after an injury. Early treatment produces better outcomes, so aim to be seen within the first few days. Seek immediate care if there is significant bleeding, visible bone, severe deformity, or numbness in the finger.

If you suspect you have mallet finger, seeking medical attention within the first one to two weeks of injury gives you the best chance of a good outcome. While mallet finger is not a medical emergency that requires immediate hospital care, delaying treatment can result in poorer healing and increased risk of permanent deformity. The sooner proper splinting begins, the better the tendon can heal in the correct position.

In most healthcare systems, a mallet finger injury can be appropriately managed by your primary care physician, an urgent care clinic, or a hand therapy clinic with occupational therapists who specialize in hand injuries. Many countries have rapid-access hand injury clinics specifically designed for conditions like mallet finger, which allow patients to be seen quickly without needing an emergency department visit.

There are certain situations where more urgent evaluation is warranted. If the injury resulted in a visible open wound over the fingertip, if bone is exposed, or if there is significant bleeding, you should seek care immediately as these indicate an open injury that needs prompt treatment to prevent infection. Similarly, if the finger appears significantly deformed beyond the typical mallet droop, if there is numbness or tingling in the fingertip, or if the finger appears pale or blue, immediate evaluation is necessary.

What to Expect at the Doctor's Visit

When you see a healthcare provider for suspected mallet finger, they will take a history of how the injury occurred and examine your finger. The examination involves observing the characteristic droop, testing your ability to actively extend the fingertip, checking passive range of motion, and assessing for tenderness over the back of the DIP joint. They will also evaluate the skin, circulation, and sensation in the fingertip.

Most patients with suspected mallet finger will have an X-ray taken. This is important to determine whether there is a bony avulsion fracture and, if so, how large the fragment is. X-rays also reveal whether the joint surfaces are properly aligned (congruent) or if there is any subluxation (partial dislocation) of the joint. These findings influence treatment decisions, particularly regarding whether surgical consultation is needed.

How Is Mallet Finger Diagnosed?

Mallet finger is diagnosed through physical examination showing the characteristic drooping fingertip that cannot be actively straightened but can be passively extended. X-rays are routinely performed to identify bony avulsion fractures and assess joint alignment. The diagnosis is usually straightforward based on the clinical presentation.

The diagnosis of mallet finger is primarily clinical, meaning it is made based on the history of injury and physical examination findings. The combination of a trauma mechanism involving forced flexion of the fingertip, the characteristic drooping appearance, and the inability to actively straighten the DIP joint while passive extension remains possible is essentially diagnostic. Experienced clinicians can often make the diagnosis within moments of seeing the finger.

During the examination, the healthcare provider will systematically assess several aspects of the finger. They observe the resting position of the finger, noting the degree of droop at the DIP joint. They test active extension by asking you to straighten your finger as much as possible – in mallet finger, the DIP joint remains flexed while the PIP (middle) joint extends normally. They then test passive extension by gently straightening the fingertip with their hand – this should be possible with normal range, unless there is associated joint damage or swelling limiting movement.

Palpation (feeling) of the finger reveals tenderness over the dorsal (back) surface of the DIP joint, where the tendon inserts. The examiner will also assess the skin integrity, looking for any wounds that might indicate an open injury. Circulation and sensation in the fingertip are checked to ensure there is no vascular or nerve damage, which would change the urgency and nature of treatment.

X-Ray Findings

X-rays are an essential part of the mallet finger evaluation. Lateral (side-view) radiographs of the affected finger provide the most useful information. These images can show whether the injury is purely tendinous (no visible bony abnormality) or involves an avulsion fracture. If a fracture is present, the X-ray reveals the size of the bone fragment, which is typically described as a percentage of the joint surface involved.

Perhaps most importantly, X-rays assess joint congruence – whether the joint surfaces remain properly aligned. In some bony mallet fingers, particularly those with larger fracture fragments, the distal phalanx may subluxate (partially dislocate) in a volar (palm-ward) direction. This joint subluxation is a key finding that often indicates the need for surgical consultation, as splinting alone may not maintain adequate joint alignment.

Classification of Mallet Finger

Healthcare providers may classify mallet finger injuries to guide treatment decisions. The most commonly used system divides injuries into types based on the mechanism and findings. Type I involves a closed tendinous injury with or without a small avulsion fracture. Type II is an open injury with tendon laceration. Type III involves a large bony avulsion (typically more than one-third of the joint surface) or joint subluxation. Understanding the type helps determine whether splinting alone is appropriate or if surgical consultation is needed.

How Is Mallet Finger Treated?

Mallet finger is treated with continuous splinting for 6-8 weeks, keeping the fingertip straight while allowing the tendon to heal. The splint must be worn 24 hours a day without removal. After initial splinting, gradual weaning over 2-4 weeks follows. Surgery is rarely needed and is reserved for specific situations like large bone fragments or joint subluxation.

The cornerstone of mallet finger treatment is splinting. The principle is simple: by holding the fingertip in a straight (or slightly hyperextended) position continuously, the torn tendon ends are brought into contact and can heal. This requires absolute immobilization of the DIP joint – even brief removal of the splint or bending of the fingertip can disrupt the healing tissue and effectively reset the clock on recovery. This is why patient understanding and compliance are so crucial to successful treatment.

Multiple splint designs are used for mallet finger, all sharing the common goal of immobilizing the DIP joint in extension. Stack splints are perhaps the most commonly used – these are pre-formed plastic splints that fit over the fingertip and hold it straight. Custom-molded thermoplastic splints are made by hand therapists and can be tailored precisely to the individual finger. Aluminum and foam splints offer another option that can be easily adjusted. The choice of splint often depends on local practice, patient factors, and the treating therapist's preference.

Regardless of splint type, the key principles remain the same. The splint should hold the DIP joint in neutral or slight hyperextension (about 0-10 degrees). The PIP joint (middle joint) should remain free to move – immobilizing this joint is unnecessary and can lead to stiffness. The splint must be comfortable enough to wear continuously but secure enough to prevent any flexion of the fingertip. Regular monitoring by a hand therapist ensures the splint remains properly fitted and the skin underneath stays healthy.

Treatment Timeline

The typical treatment protocol involves three phases. During the first phase (weeks 1-6 or 1-8), the splint is worn continuously, 24 hours a day, 7 days a week. The only exception is brief splint changes if the skin becomes wet or irritated, and even during these changes, the fingertip must be kept absolutely straight – patients are taught to support the finger on a flat surface while changing splints. Active movement of the PIP joint is encouraged during this phase to prevent stiffness.

The second phase (weeks 6-10 or 8-12) involves gradual weaning from the splint. Patients begin removing the splint for short periods during low-risk activities, while continuing to wear it during sleep, sports, and any activities with risk of re-injury. Active extension exercises begin under therapist guidance. The weaning schedule is individualized based on healing progress.

The final phase focuses on return to full activity. The splint is discontinued once active extension is stable, though it may be recommended for sports or heavy manual work for several additional weeks. Gentle strengthening exercises may be prescribed. Full recovery typically takes 3-4 months from the initial injury, though some residual stiffness or minor extension lag is common.

When Is Surgery Needed?

Surgery for mallet finger is uncommon, with conservative splinting being successful in the vast majority of cases. However, surgical consultation is appropriate in certain situations. These include bony mallet injuries where the avulsion fragment involves more than one-third of the joint surface, injuries with volar subluxation of the distal phalanx, open injuries requiring wound management, and cases where prolonged conservative treatment has failed.

When surgery is performed, various techniques may be used depending on the specific injury pattern. Options include pinning the joint in extension, using small screws or wires to fix large bone fragments, or tendon repair for open injuries. The surgeon will discuss the specific approach and expected outcomes based on the individual injury characteristics.

What Can You Do Yourself for Mallet Finger?

While professional splinting is essential, you can support healing by keeping the splint dry and clean, monitoring for skin problems, maintaining movement in non-affected joints, managing pain with over-the-counter medications, and strictly following the splint-wearing schedule. Never bend the fingertip during treatment.

Self-care plays an important role in mallet finger treatment, complementing the professional splinting and therapy you receive. Your daily actions and vigilance can significantly influence the outcome. Understanding what you can do at home helps you become an active participant in your recovery rather than a passive recipient of treatment.

Splint care is paramount. Keep the splint dry during bathing by using a waterproof cover or keeping your hand out of the water. If the splint becomes wet, dry it carefully – for stack splints, you can tape the finger to a flat surface (like a tongue depressor) while drying, ensuring the fingertip never bends. Check the splint fit daily; it should be snug but not tight enough to impair circulation. Watch for signs of skin irritation including redness, blistering, or maceration (soft, white, wrinkled skin from moisture).

Maintaining movement in your non-affected joints is important to prevent stiffness. Gently bend and straighten the middle joint (PIP) of the affected finger several times a day – only the tip needs to stay still. Move all the joints of your other fingers normally. These exercises maintain flexibility and prevent the secondary stiffness that can complicate recovery if the whole hand becomes immobile.

Pain Management

Most mallet finger injuries cause relatively mild pain that can be managed with over-the-counter medications. Paracetamol (acetaminophen) is usually sufficient for discomfort. Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen can help if there is significant swelling, though some practitioners prefer to avoid these as they may theoretically slow tendon healing – ask your healthcare provider for guidance. Elevation of the hand above heart level during the first few days can help reduce swelling.

If pain is severe or worsening despite medication, this warrants a check-up to ensure the splint is properly fitted and there are no complications. Pain should gradually improve over the first one to two weeks; persistent or increasing pain may indicate a problem that needs professional assessment.

What to Avoid

The most important thing to avoid is any bending of the fingertip during the splinting period. This means being extremely careful during splint changes and avoiding activities that might knock the splint or stress the finger. While most work and daily activities can continue, you should avoid situations where the finger might be caught or struck, and you may need to modify how you perform certain tasks.

What Happens After Mallet Finger Treatment?

After completing splint treatment, most patients achieve good finger function, though a small permanent droop of 5-10 degrees is common. Full recovery takes 3-4 months. Occupational therapy may be recommended for exercises to restore strength and flexibility. Return to sports and heavy activities is usually possible after 3 months.

The outcome after mallet finger treatment depends on several factors, including the type of injury, how quickly treatment was started, and how well the splinting protocol was followed. With proper treatment, the majority of patients – approximately 80-90% – achieve a satisfactory result with functional finger movement and minimal residual deformity.

It is important to have realistic expectations about the outcome. While the goal is to restore full extension of the fingertip, many patients are left with a small residual extension lag – the inability to completely straighten the DIP joint. An extension lag of 5-10 degrees is considered an acceptable outcome and typically does not significantly impact function. Larger extension lags (more than 20 degrees) or painful limitation of movement may require additional treatment or evaluation.

After the splint is discontinued, the finger may feel weak and stiff initially. The strength and flexibility improve over several weeks to months as normal use resumes. Occupational therapists can prescribe specific exercises to accelerate this recovery, including gentle stretching, grip strengthening, and dexterity activities. Most patients return to near-normal function within 3-4 months of the initial injury.

Long-Term Outcomes

Long-term studies of mallet finger treatment show generally favorable results. Most patients report being satisfied with their outcome and able to return to their previous activities, including sports and work requiring fine motor skills. The cosmetic appearance is usually acceptable, though some patients notice that the affected finger looks slightly different from the others.

Complications are uncommon but can occur. The most frequent issue is persistent extension lag, which may be purely cosmetic or occasionally functionally limiting. Secondary swan neck deformity – where the middle joint hyperextends while the fingertip remains drooped – can develop if the mallet injury is not adequately treated. This deformity affects hand function and can be difficult to correct. Arthritis of the DIP joint is possible in the long term, particularly following bony mallet injuries, though this is not always symptomatic.

Return to Activities

Returning to work is usually possible throughout treatment for most occupations. Office workers, professionals, and those in light duty jobs can typically continue working while wearing the splint. Manual laborers, healthcare workers, and others whose jobs require extensive hand use may need modified duties or temporary restrictions. Discuss your specific work requirements with your treating therapist or physician.

Return to sports follows a more gradual timeline. Low-risk activities like walking, cycling, and swimming (with waterproof splint protection) can continue during treatment. Ball sports and activities with significant risk of finger injury should be avoided until the splint is discontinued and the finger has regained strength, typically around 3 months from the initial injury. Protective taping or a soft splint may be recommended for sports participation for an additional few weeks.

What Complications Can Occur with Mallet Finger?

Potential complications of mallet finger include persistent extension lag, swan neck deformity, skin problems from splinting, joint stiffness, and DIP joint arthritis. Most complications can be minimized with proper treatment and monitoring. Untreated mallet finger carries the highest risk of permanent deformity.

While mallet finger generally has a good prognosis with proper treatment, complications can occur. Understanding these potential issues helps patients recognize problems early and seek appropriate care. Most complications are manageable, especially when identified promptly.

Persistent extension lag is the most common complication, occurring to some degree in a significant proportion of treated patients. A small extension lag (less than 10-15 degrees) is usually considered acceptable and rarely affects function. Larger lags may occur due to inadequate healing of the tendon, often related to poor splint compliance, delayed treatment, or severe initial injury. If a significant lag persists after completing the standard treatment protocol, additional splinting or, rarely, surgical intervention may be considered.

Swan neck deformity is a secondary complication that can develop in untreated or inadequately treated mallet finger. When the extensor mechanism at the DIP joint is disrupted, the forces acting on the finger become unbalanced. Over time, the lateral bands that normally extend the DIP joint can migrate upward, causing the PIP joint to hyperextend while the DIP joint remains flexed. This characteristic deformity significantly impacts hand function and can be challenging to correct once established.

Skin Complications

Skin problems under the splint are common but usually preventable with good care. Maceration (soft, white, soggy skin) occurs when the skin stays wet, emphasizing the importance of keeping the splint dry. Pressure sores can develop if the splint is too tight or has sharp edges. Allergic reactions to splint materials are occasionally seen. Regular monitoring of the skin during treatment, with prompt reporting of any problems to the hand therapist, allows early intervention before serious skin breakdown occurs.

Stiffness

Stiffness of the treated finger is common during and after splinting but usually resolves with time and exercise. The DIP joint may be stiff initially after splint removal, requiring gentle stretching to regain full flexion. More concerning is stiffness of the PIP joint, which should remain free during mallet finger treatment. If the PIP joint becomes stiff, this may indicate that the splint was incorrectly applied (immobilizing both joints) or that the patient was not performing the recommended PIP mobility exercises.