What is Fifth Metacarpal Fracture?
Fractures of the metacarpals, the bones in the hand, make up 40% of all hand fractures. A type of these fractures, called fifth metacarpal fractures, account for 20% of all hand fractures. These are common amongst young and active individuals. Some particular types of these fractures can lead to functional problems reducing the strength of the little finger’s grip and its joint mobility. As a result, it can lead to decreased manual dexterity, causing people to miss work and face financial consequences.
A boxer’s fracture involves the break of the neck of the fifth metacarpal, so-called because it typically results from direct trauma to a clenched fist. These fractures constitute 10% of all hand fractures. How it’s treated depends on several factors including whether it’s an open or closed fracture and its severity. Closed, mild fractures without angulation or rotation are typically treated with immobilization through an ulnar gutter splint. In contrast, severe fractures or those with nerve or blood vessel involvement may require surgery.
The metacarpals form the skeleton of the palm, connecting the wrist bones to the finger bones. Each finger, including the thumb and little finger, is supported by a metacarpal bone. A metacarpal bone has a head, shaft, neck, and base. The head links to the finger’s proximal bone distally, or toward the end, while the bases link to the wrist bones proximally, or toward the center. The neck, which is often involved in boxer’s fractures, is the slim portion of the metacarpal bone just past the base.
These metacarpal bones provide the structure for the palm and are the points where muscles attach, granting the hand the ability to move and grip. The second through fifth metacarpal bones are closely attached, making isolated fractures normally stable. The hand’s bones have a high blood supply, resulting in quick healing of fractures unless they are severe or crushed. However, if not properly treated, fractures could have a significant impact on hand function, affecting day-to-day activities, work, and sports.
What Causes Fifth Metacarpal Fracture?
A boxer’s fracture typically happens when a heavy force is applied to a clenched fist, like punching. Other causes can include a direct hit to the hand, an object hitting the hand, or injury to the back of the hand. This can result in a fracture to the neck of the 5th metacarpal bone (one of the long bones in the hand), which is specific to a boxer’s fracture.
Interestingly, unlike many other hand and wrist fractures, a boxer’s fracture usually doesn’t result from a fall onto an extended hand.
In addition to punching, metacarpal fractures can also be caused by several other factors such as falls, sports-related injuries, direct blows to the hand, and car accidents.
Risk Factors and Frequency for Fifth Metacarpal Fracture
Metacarpal neck fractures, or breaks in the bones in the hand, are quite common, with a rate of 13.6 cases per 100,000 people per year in the United States. About 40% of all hand fractures are of the metacarpals. Specifically, fractures of the 5th metacarpal neck, one specific bone in the hand, make up about 10% of these. Males are affected by this injury much more commonly than females, with five times as many cases. Particularly, boys and young men between the ages of 10 and 29 are the most affected. These injuries typically happen at home or during sports events.
- 13.6 in every 100,000 people will have a metacarpal neck fracture each year in the US.
- 40% of all hand fractures happen in the metacarpals.
- 10% of these are fractures of the 5th metacarpal neck.
- Males are 5 times more likely to experience this fracture than females.
- Young men aged 10 to 29 are at the highest risk.
- These injuries often happen at home or at sporting events.
Signs and Symptoms of Fifth Metacarpal Fracture
People with broken bones in their hands (known as metacarpal fractures) often have pain, swelling, and a distorted shape in the back of their hand. This usually happens after an event that could cause such an injury. They may also see some bruising and struggle to move the fingers on the side of their hand closest to their body.
When a doctor checks out the injured hand, they carefully compare it with the other hand. They look at several things:
- Skin: The doctor will look very closely at the skin to see if there are any cuts or scrapes, especially near the knuckle. If the bone has broken the skin, immediate surgery is needed. There’s a special type of injury called a “fight bite” that can happen if someone fractures their hand by punching someone in the face and a tooth leaves a cut or scrape. These also often need to be cleaned out with surgery.
- Neurovascular exam: When evaluating potential broken bones, it’s important to check feeling, movement, and blood flow in the parts of the hand further away from the body than where the injury occurred. It’s rare, but sometimes swelling can cause a dangerous condition called ‘compartment syndrome’ in the hand. If this isn’t caught and treated early, it can result in loss of function.
There are also two other specific things that are checked with this kind of fracture:
- Angulation: Fractures resulting from punching (known as “boxer’s fractures”) usually have a notable bend toward the back of the hand, leading to a depression in the knuckle and loss of normal shape. If the fracture is significantly bent, “pseudoclawing” can be seen due to damage to the tendons that help extend the fingers. This undesired positioning is when the finger joints closest to the hand extend too much, and the next set of joints are too flexed. X-rays can help determine how much the bone is bent.
- Rotational alignment: Any degree of twisting or turning of the broken bone is a reason to see a hand surgeon. To check for this, the doctor might have you bend your hand with certain finger joints bent and others extended. If the fingers are properly aligned, lines drawn along the fingers should come together. If the line from the pinky finger doesn’t join with the others, there might be a suspicion of rotational malalignment (twisting). This can also be checked by making sure the fingernails line up when the hand and fingers are positioned in a certain way.
Testing for Fifth Metacarpal Fracture
If you think you may have broken one of your metacarpal bones in your hand (often called a boxer’s fracture), your doctor will likely use x-ray images to check for a fracture. These images would include views from the front, side, and an angled view. The side view is particularly useful for measuring the angle of any bends in the bone caused by the fracture. Normally, the head and neck of the metacarpal form an angle of about 15°, but if there’s a break, this angle is usually bigger.
A specific type of x-ray called Brewerton’s imaging technique may also be used. For this technique, your hand is laid flat on the x-ray plate, and your finger joints are bent at a 65° angle. The x-ray beam is then angled 15° towards the ulnar side of your hand (the side with your little finger).
Recent studies have found that ultrasound can also be used to diagnose a metacarpal fracture. Normally, computed tomography (a CT scan) isn’t used for diagnosing these fractures. However, if x-rays don’t show a fracture but you have signs of a break, a CT scan can often detect damage to the metacarpal head or hidden fractures in other bones.
Treatment Options for Fifth Metacarpal Fracture
When you get bitten during a fight, you risk infection. Even small wounds need to be thoroughly cleaned and sanitized. Larger wounds often need antibiotics and a medical procedure where damaged tissue is removed.
Boxer’s fracture, a common injury where the bone of the little finger breaks, is treated differently based on the type and intensity of the fracture. Let’s look at a few treatments:
Using a Cast or Splint
If the fracture isn’t bent out of place or isn’t affecting movement of the hand, a splint can be used to keep the hand still until it heals. This is usually done using a special splint that covers the side of the arm. Sometimes, a molded support may be used.
In this case, the hand is positioned in a way where the wrist, middle and end of the fingers are slightly bent. This helps to avoid the joints shortening and causing loss of movement or function in the hand.
Adjusting the Position of the Broken Bone
The bone may need to be moved back into its place if the fracture is angled more than 30 degrees. The method usually used involves bending the finger joints while applying pressure over the fracture site. This helps to push the broken fragment of the bone back into position. After this is done, a splint is used to keep the hand still and X-rays are taken to check if the bone has been properly positioned. If it’s within acceptable limits, no surgery is required.
Surgery
Surgery may be needed for severe cases. This includes fractures that are open, heavily crushed, twisted, or associated with nerve or blood vessel injuries. Surgery might also be needed for bones that didn’t heal properly or if the bone didn’t move back to the correct position after non-surgical treatment. After surgery, the bone is fixed in place with screws or other methods.
Follow-Up Care
Your doctor will take X-rays about once a week to check if the bone is healing properly. You may need to do so every few weeks until the bone is fully healed, which usually takes around a month to a month and a half. Even after correct treatment, some changes in the hand’s appearance like the loss of knuckle shape may occur. After a short time of keeping the hand still, exercises that involve moving the finger joints can help avoid stiffness . Studies show starting exercises earlier rather than keeping the injury still for a long time, can help these injuries. If you’re still having trouble using your hand after weeks of physical therapy, you might need occupational therapy which focuses more on improving your hand’s function.
What else can Fifth Metacarpal Fracture be?
When a doctor is trying to diagnose a fracture in the 5th metacarpal (one of the bones in your hand), there are other conditions that could potentially cause the same symptoms. Some of these might include growths in the bone known as chondromas, a deep cut in the soft tissues of the hand, and types of cancer known as sarcomas.
Another condition that might be considered is a ‘boxer’s knuckle’. This is a tear in a certain part of the knuckle joint (the sagittal band) that causes the tendon, a kind of strong tissue, to shift out of place.
To tell these conditions apart from a metacarpal fracture, doctors will usually rely on the patient’s medical history, and might also use imaging techniques such as X-rays.
What to expect with Fifth Metacarpal Fracture
Studies show that if you break your 5th metacarpal neck (the long bone in your hand leading to your little finger), and it’s angled less than 70° with no rotation, your hand will still function highly effectively. This is as per the quickDASH scores (a measure for hand injuries) taken at four months after the injury. Usually, these breaks tend to heal within eight weeks without any complications. That being said, total recovery might take several months.
Common signs of a broken 5th metacarpal include pain, stiffness, weakened muscle strength, and a bump at the injury site. Despite these symptoms, this kind of injury generally doesn’t have a severe impact on your hand’s functionality. However, it’s worth noting that if you have diabetes or if you smoke, it could slow down the healing of the broken bone.
Possible Complications When Diagnosed with Fifth Metacarpal Fracture
When the neck of the 5th metacarpal bone in the hand is fractured, there can be several complications. These may include the finger being rotated out of position, the fracture not healing (nonunion), stiffness of the joint, a weaker grip, damage to nerves and blood vessels, and loss of the 5th knuckle’s aesthetic appearance. Open fractures, or those sustained from a punch (fight bites), carry a higher risk of infection. If a fracture doesn’t fully heal, it can lead to ongoing pain and even re-break. All these risks should be discussed with the patient when considering surgical and nonsurgical treatments.
Common complications:
- Malrotation of the digit
- Nonunion
- Joint stiffness
- Grip weakness
- Neurovascular injury
- Loss of the 5th knuckle’s aesthetic appearance
- Infections from open fractures or fight bites
- Chronic pain from incompletely healed fractures
- Refracture
Recovery from Fifth Metacarpal Fracture
Physiotherapy is especially important in helping restore full functionality of the hand. The main goals of rehabilitation are to regain full muscle strength and achieve the best possible flexibility. Correctly applying a splint or brace is key, as not doing so can cause stiffness, pressure sores, or even compartment syndrome, which is a very serious condition. For these types of fractures, the best way to splint the wrist is to position it at a 20° extension, bend the MCP joint to between 60° and 70°, and extend the interphalangeal joint.
After surgery, starting exercises that help increase the movement range, without any resistance, is typically suggested around 2 to 3 weeks after the injury. These types of exercises help prevent scarring, improve blood flow at the fracture site, and reduce swelling. Passive movements can be started once the clinical and x-ray examinations show sufficient healing. For most hand bone fractures, gentle resistance exercises can usually start about 4 weeks after the injury. However, the active movement should be restricted when healing has not yet begun.
Preventing Fifth Metacarpal Fracture
Boxer’s fractures often occur due to damage to the fifth bone in the hand, and usually result from powerful impacts. There are several steps that can be taken to prevent these injuries, such as wearing protective gear for your hands, using the correct motion when participating in sports, avoiding reckless behavior, and making sure your home is safe. If complications arise following an injury, further preventive actions may be necessary.
For patients experiencing minimal pain and no abnormal twisting of the bone, a simple approach might be enough, even if the bone is somewhat bent. However, if the bend is severe, if there are multiple fractures on the bone, if there are injuries to the nerves or blood vessels, if the hand function is seriously affected, or if the pain is intense, a specialist hand surgeon should be consulted. Annoying twisting of the bone is not okay because it considerable impacts the hand’s function and it causes fingers to cross over when making a fist.
Patients should understand the need for check-up appointments and sticking with the rehabilitation plan after their treatment. Ensuring patients follow these steps, speeds recovery, and reduces the risk of further complications.
