What is a mallet finger injury?

Mallet finger injuries (MFI) affect the fingertip joint, called the distal interphalangeal (DIP) joint.¹ They are usually caused by sudden, forceful movement of the DIP joint, which causes the fingertip to droop so that you are unable to straighten it back into its original position.¹ This is because the ‘extensor force’ that allows you to straighten or extend your finger is lost between the middle joint of the finger, called the proximal interphalangeal (PIP) joint, and the DIP joint.¹ Resultantly, MFIs are a common finger injury among athletes and people who play sports.¹

Typical symptoms of MFIs include a drooping fingertip that you are unable to straighten, pain, tenderness, and possible swelling and bruising around the joint.² If you go to the doctors with these symptoms, they may recommend an X-ray to have a look at your finger and help make a diagnosis.^2,3  

MFIs can be either soft-tissue or bony mallet injuries.⁴ 

Soft-tissue MFIs occur when a tendon is ruptured or divided.^3,4 Tendons are found throughout the body.⁵ They are tough and fibrous but flexible tissues that connect bones and joints.⁵ They pass forces created by muscles to bone, which allows the finger to move.⁵ When a tendon becomes damaged in a soft-tissue MFI, these forces are disrupted, so the finger droops and is no longer able to straighten.³ 

Bony MFIs occur when a tendon injury causes an avulsion fracture.^3,2 This is when a fragment of bone is pulled away from the rest of the bone by the soft tissue to which it is attached.⁶ This also causes the extensor forces to be disrupted so that the finger droops and is no longer able to straighten.³

The injury can then be further classified into more specific subtypes using the Patel-Gerberman, Wehbe-Schneider and Doyle classification systems.^1,4

Patel-gerbeman classification

The Patel-Gerbeman classification categorises the MFI based upon the time that has elapsed since the initial injury. This is used to determine whether an MFI is acute (an injury that occurs suddenly) or chronic (a long-term injury).⁷ Acute MFIs have lasted for less than 4 weeks after the initial injury, whereas chronic MFIs have lasted for longer than 4 weeks since the initial injury.¹

Wehbe-schneider classification

The Wehbe-Schneider classification is a set of criteria that is used only to categorise bony MFIs. It categorises fractures into three types based on the extent of the bone fracture, and then into three further subtypes based on the degree to which the injury involves the joint.¹ 

The doyle classification

The Doyle classification is a set of criteria that can be used to describe both bony and soft-tissue MFIs. It considers whether the injury is open (the skin is broken) or closed (the skin is not broken), and also how severe the bone fracture is.^1,4

These classifications can help inform a doctor about which type of treatment would best help your MFI heal.

How are mallet finger injuries treated?

Treatments for MFIs aim to bring your tendon or bone back together to allow your finger to heal and restore the ability to straighten your finger.⁸ The initial treatment for mallet-finger injuries is usually a finger splint.¹ Splints are medical devices that are put onto your finger to keep it straightened and extended.¹ They are usually used for around 6-8 weeks, allowing the DIP joint to heal back into its original position.^3,9

Most splints work in a similar way, but there are many different types of splints made from a range of materials, including plastic, thermoplastic, and aluminium.¹ A doctor will help you to decide which splint is the best for your injury and lifestyle. If splinting does not work, a doctor may consider surgery as the next step in your treatment, but this is rare.^1,2 

After treatment, it may take several months for your finger to return to normal.²

How is healing measured?

The Crawford scale is usually used to evaluate how well your MFI has healed.^1,9 

Table detailing the Crawford scale for mallet finger injuries. Created by Chloe Donkin.

Why do some mallet finger injuries heal better than others?

Delayed treatment

If mallet finger injuries are left untreated, they can worsen, leading to the affected fingertip becoming stiff or misshapen.⁴ In the most extreme cases, this can result in complications like:

• Prolonged pain⁹ 
• Extensor lag, a condition where you cannot straighten your finger fully without assistance^4,9
• Swan-neck deformity, a condition that causes the finger to bend abnormally, resembling the shape of a swan’s neck^1,4,9
  • It happens when the mechanism that allows your finger to straighten is severely impaired, causing the PIP joint to be bent backwards and the DIP joint to be bent forward^10,11 

Treating MFIs early can help to avoid worsening injuries; however, they can still occur after treatment.³

Type and severity of your injury

The type and severity of your MFI can affect how well it will heal.

Bony vs soft-tissue MFIs

When treated properly, bony MFIs are likely to heal faster than soft-tissue MFIs.¹² This means that you may need to use a splint for a longer period of time if you have a soft-tissue MFI.¹²

MFI severity

The severity of your MFI can affect healing time; if classified as more severe using the Wehbe-Schneider and Doyle classification systems, it may take longer to heal with just a splint, or it may require surgery. Typically, open injuries with more severe fractures take longer to heal.⁴ 

Acute vs. chronic MFIs

Most acute injuries can heal well without surgery using a splint. Some chronic injuries may be treated with a splint if they are caught early enough (4–8 weeks after the injury) and if the finger is not stuck in an abnormal position.¹ Surgery may be necessary as a treatment for severe acute injuries, severe chronic injuries, and chronic injuries that do not respond to splinting. 

Your age

Older adults are more likely to become injured from lower-impact activities, like making a bed, than younger adults and children.¹³ They may also experience a slower healing process and necessitate additional care.⁸ They are also at a higher risk of experiencing complications following an MFI, like extensor lag (where you cannot straighten your finger fully without assistance), joint stiffness and weaker tendons and bones, which increases the risk of a subsequent injury occurring.^5,8,9,14,15, 

Not using your splint properly

Splinting is the most common treatment for MFIs.¹ Using a splint properly and continuously for the period recommended by your doctor is essential for healing a mallet finger injury.⁹ Removing the splint too soon or not using the splint properly means that your injury is less likely to heal fully.⁹

This includes:

• Keeping the injured fingertip in a supported and straight position at all times²
• Changing or cleaning the splint properly by following the guidance provided by your doctor on how to reapply and secure a new splint^1,2
• Cleaning the skin on the injured finger regularly^1,2
• Keeping the splinted finger dry at all times
  • This is because the wet skin can struggle to dry underneath the splint, meaning that your finger can become sore 
  • If the finger does get wet, you should change the splint²
• Wearing the splint for the amount of time that your doctor has recommended to make sure that the tendon or bone is brought back together²

Splint complications

Sometimes, there are complications that can make it difficult to wear a splint. This includes irritation of the area where you are wearing the splint, ulcers, skin damage and partial joint dislocation.¹⁶

Surgical complications

There are sometimes complications that occur after surgery that make healing difficult. This includes, but is not limited to, infections, nail abnormalities, joint incongruity (where the finger joints do not align or fit together properly) and pain.^1,16 Additionally, surgical treatments for MFIs often use a wire to straighten the joints.¹ Sometimes, these wires can be inadequately placed or can loosen, break or move. This leads to ‘implant failure’, which can complicate the healing process.^1,16,17 

Occupational or lifestyle demands

If you have a physically demanding job or hobby that involves the use of your hands, you may be more likely to reinjure yourself or delay the healing process.

• Depending on your job, you may need to take some time off from work 
• You should avoid sports or exercise involving your hands while you are healing 

When to seek help?

The NHS website advises that you should call 111 or get help from 111 online if:

• You cannot straighten your finger 
• Your finger is painful or tender 
• Your finger is swollen or bruised

Final thoughts

Mallet finger injuries are usually very treatable with successful results when they are treated early.⁴ Despite this, several factors can influence how well your injury heals. For the best chances of healing:

• You must use your splint properly and follow the instructions provided by your doctor^2,9
• To allow the finger to heal, you must not bend your finger during this time
• You should avoid reinjury by limiting activities that put your finger at risk²
• You should perform hand exercises if advised to do so by your doctor²

Summary

Mallet finger injuries (MFI) occur when the tendon or bone at the fingertip is damaged, causing the distal interphalangeal (DIP) joint to droop. They are classified by timing (acute vs. chronic), fracture severity, and whether the injury is open or closed. Most cases are treated with splinting for 6–8 weeks, while surgery is only needed for severe or unresponsive cases. Healing is assessed using the Crawford scale.

Poor outcomes are more likely with delayed treatment, severe or chronic injuries, older age, improper splint use, splint or surgical complications, and reinjury from occupational or lifestyle demands. Despite these risks, most MFIs heal successfully if treated early and managed properly.