Metacarpal Fractures – Causes, Symptom, Treatment

Metacarpal fractures
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Metacarpal fractures account for 40% of all hand fractures.  A Boxer’s fracture is a fracture of the fifth metacarpal neck, named for the classic mechanism of injury in which direct trauma is applied to a clenched fist.  This represents 10% of all hand fractures. Treatment for a Boxer’s fracture varies based on whether the fracture is open or closed, characteristics of the fracture including the degree of angulation, shortening, and rotation, and other concomitant injuries. Immobilization with an ulnar gutter splint may be the definitive treatment for closed, non-displaced fractures without angulation or rotation, while open fractures, significantly angulated or malrotated fractures or those involving injury to neurovascular structures may require operative fixation.

Pathophysiology

The fifth metacarpal bone is one of the five metacarpal bones of the hand. The fifth metacarpal is associated with the fifth digit. The metacarpal bone consists of a head (distally located), neck, body, and base (proximally located). Axial load via direct trauma to a clenched fist transfers energy to the metacarpal bone, causing fractures most commonly at the neck, and typically resulting in apex dorsal angulation due in part to the forces exerted by the pull of the interosseous muscles. The interosseous muscles, responsible for adduction and abduction of the fingers, originate from the metacarpal shafts and insert onto proximal phalanges. The collateral ligaments also join the metacarpal bones to the proximal phalanges and must be taken into consideration during splinting to minimize the risk of loss of motion due to shortening of the ligaments. The ligaments are taut in flexion, and more slack in extension, therefore the MCP joints should be splinted in flexion to prevent shortening (intrinsic plus positioning). The arteries and nerves supplying the fingers are adjacent to the metacarpal bones and can be injured in severely displaced Boxer’s fractures, requiring surgical intervention.

Metacarpal fractures

Causes Of Metacarpal Fractures

The most common mechanism of injury for Boxer’s fracture is punching, e.g., the axial pressure applied to the metacarpal bone when the fist is in a clenched position. Direct trauma to the dorsum of the hand may also cause a fracture of the fifth metacarpal neck. Unlike many other hand and wrist fractures, a Boxer’s fracture typically does not occur with a fall onto an outstretched hand.

Metacarpal fractures

  • Injury to the phalanges – occurs with direct, blunt trauma, penetrating trauma, and crush injuries.
  • Sudden forceful  fall down
  • Road traffic accident
  • Falls – Falling onto an outstretched hand is one of the most common causes of broken and fractures.
  • Sports injuries – Many fractures occur during contact sports or sports in which you might fall onto an outstretched hand — such as in-line skating or snowboarding.
  • Motor vehicle crashes – Motor vehicle crashes can cause wrist bones to break, sometimes into many pieces, and often require surgical repair.
  • Have osteoporosis –  a disease that weakens your bones
  • Eave low muscle mass or poor muscle strength – or lack agility and have poor balance (these conditions make you more likely to fall)
  • Walk or do other activities in the snow or on the ice – or do activities that require a lot of forwarding momenta, such as in-line skating and skiing
  • Wave an inadequate intake of calcium or vitamin D
  • Football or soccer, especially on artificial turf
  • Rugby
  • Horseback riding
  • Hockey
  • Skiing
  • Snowboarding
  • In-line skating
  • Jumping on a trampoline

Symptoms of Metacarpal Fractures

The symptoms are pain and tenderness in the specific location of the hand, which corresponds to the metacarpal bone around the knuckle.

  • There will be swelling of the hand along with discoloration or bruising in the affected area. Abrasions or lacerations of the hand are also likely to occur. The respective finger may be misaligned, and the movement of that finger may be limited and painful.
  • Painful bruising and swelling of the back and front of the hand
  • The pain of the back of the hand in the area of the fractured 5th metacarpal
  • The bent, claw-like pinky finger that looks out of alignment
  • Limited range of motion of the hand and of the 4th and 5th fingers
  • When a fracture occurs, there may be a snapping or popping sensation.
  • Tenderness near the base of the pinky finger
  • Inability or limited ability to move the pinky or ring finger
  • The knuckles of the affected finger appearing flat and no longer protruding as usual
  • Problems trying to grip with the injured hand
  • Numbness
  • Coldness in the hand

Metacarpal fractures

Diagnosis of Metacarpal Fractures

History and Physical

Patients with Boxer’s fractures present with complaints of dorsal hand pain, swelling, and possible deformity in the setting of one of the mechanisms typically associated with this injury involving direct trauma to the hand.

Complete physical exam of a potential Boxer’s fracture should include an examination of the entire hand, comparison to the contralateral hand, with special attention to the following:

  • Skin – Closely inspect the skin for any breaks, especially near the metacarpal head, typically the point of impact. When a Boxer’s fracture is sustained by a blow to the face, the recipient’s tooth may cause a laceration or abrasion known as a “fight bite.” This may require operative irrigation and debridement.
  • Neurovascular exam – As with all suspected fractures, a neurovascular exam should test for sensation, motor function, and blood flow distal to the injury.
  • Angulation – Boxer’s fractures are typically associated with apex dorsal angulation, thereby resulting in depression of the MCP joint and loss of the normal knuckle contour. With significantly angulated fractures, “pseudo-clawing” may be observed due to damage to the extensor apparatus; pseudo-clawing is a hyperextension of the MCP joint and flexion at the PIP joint. The degree of angulation is determined using plain films.
  • Rotational alignment – Any degree of malrotation warrants referral to a hand surgeon and therefore assessment of rotational alignment is a crucial component of the physical exam. Alignment can be assessed by examining the hand with the MCP and PCP joints in flexion, and DIP joints extended. If lines are drawn along the digits and extended distally, normally aligned digits will show the convergence of these lines. If the line extended from the fifth finger does not converge towards the others, suspect malrotation.
  • Malrotation – can also be detected by examining the hand with the MCPs flexed, and PCPs and DIPs extended. The fingernails should be in line along a single plane.

Imaging

  • Plain radiographs – are the standard of care to diagnose Boxer’s fractures and determine a degree of angulation. Anteroposterior, lateral, and oblique views should be obtained. The lateral view should be used to measure the degree of angulation of the shaft of the metacarpal as compared to the mid-point of the fracture fragment. Normal angulation of the metacarpal head to the neck is 15 degrees, so the angulation of the fracture should be measured as that more than the baseline of 15 degrees.
  • Ultrasound – Recent literature suggests that bedside ultrasound may also be used to make an initial diagnosis of a Boxer’s fracture.
  • CT Scan – is generally not used for the diagnosis of metacarpal fractures; however occult fractures may be detected via CT in patients for whom there is a high degree of clinical suspicion for fracture and negative plain radiographs.
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Metacarpal fractures

Treatment of Metacarpal Fractures

Non-Surgical

Treatment available can be broadly

  • Get medical help immediately – If you fall on an outstretched arm, get into a car accident or are hit while playing a sport and feel intense pain in your shoulder area, then get medical care immediately.  cause significant pain in the front part of your shoulder, closer to the base of your hand. You’ll innately know that something is seriously wrong because you won’t be able to lift your arm up above the heart level. Cleaning and treating any wounds on the skin of the injured hand.
  • Apply ice to your fractured area immediately – Before going to the hospital metacarpal fractures /boxer’s fracture(regardless if you had surgery or not), you should apply a bag of crushed ice (or something cold) to your injured in order to reduce the swelling and numb the pain. Ice therapy is effective for acute (recent) injuries that involve swelling because it reduces blood flow by constricting local blood vessels. Apply the crushed for 15 minutes three to five times daily until the soreness and inflammation eventually fades away
  • Immobilization Alone – For a Boxer’s fracture that is closed, not angulated, and not malrotated or otherwise displaced, splinting is used for initial immobilization. A Boxer’s fracture should be immobilized with an ulnar gutter splint. Alternatively, a pre-made Galveston splint or a custom orthosis may be used. The hand should be positioned in the intrinsic plus position for splinting mild wrist extension, 70 to 90 degrees of flexion at MCP joint, and slight flexion at the DIP and PIP joints. Flexion of these joints is important to prevent shortening of the collateral ligaments and subsequent loss of range of motion and functional impairment.
  • Lightly exercise after the pain fades – After a couple of weeks when the swelling has subsided and the pain has faded away, remove your arm sling for short periods and carefully move your arm in all different directions. Don’t aggravate the metacarpal fractures /boxer’s fracture so that it hurts, but gently reintroduce movements to the involved joints and muscles. Start cautiously, maybe starting with light calisthenics and then progress to holding light weights (five-pound weights to start).
  • Practice stretching and strengthening exercises – of the fingers, elbow, and shoulder if your doctor recommends them.
  • A splint – which you might use for a few days to a week while the swelling goes down; if a splint is used initially, a cast is usually put on about a week later.
  • A cast – which you might need for three to five weeks or longer, depending on how bad the break is (you might need a second cast if the first one gets too loose after the swelling goes away.)
  • Get a supportive arm sling – Due to their anatomical position, metacarpal fractures /boxer’s fracture can’t be cast like a broken limb can. Instead, a supportive arm sling or “figure-eight” splint is typically used for support and comfort, either immediately after the injury if it’s just a hairline fracture or following surgery, if it’s a complicated fracture. 
  • Get a referral to physical therapy – Once you’ve recovered and able to remove your arm sling splint for good, you’ll likely notice that the muscles surrounding your metacarpal fractures /boxer’s fracture look smaller and feel weaker. That’s because muscle tissue atrophies without movement. If this occurs, then you’ll need to get a referral for some physical rehabilitation. Rehab can start once you are cleared by your orthopedist, are pain-free, and can perform all the basic arm and phalanges movements. A physiotherapist or athletic trainer can show you specific rehabilitation exercises and stretches to restore your muscle strength, joint movements, and flexibility
  • Taping the hand – as a type of soft splint, with the pinky and ring finger, taped together to help in healing correction of the dislocated bone, which may be done with anesthesia

Rest Your Hand

Once you’re discharged from the hospital in an arm sling, your top priority is to rest your hand and not further inflame the injury. Of course, the arm sling not only provides support, but it also restricts movement, which is why you should keep it on even during sleep. Avoiding the temptation to move your hand and arm will help the bone mend quicker and the pain fades away sooner.
  • Depending on what you do for a living and if the injury is to your dominant side, you may need to take a couple of weeks off work to recuperate.
  • Healing takes between four to six weeks in younger people and up to 12 weeks in the elderly, but it depends on the severity of the radial and phalangeal fractures 
  • Athletes in good health are typically able to resume their sporting activities within two months of breaking they’re depending on the severity of the break and the specific sport.
  • Sleeping on your back (with the sling on) is necessary to keep the pressure off your shoulder and prevent stress.

Eat Nutritiously During Your Recovery

All bones and tissues in the body need certain nutrients in order to heal properly and in a timely manner. Eating a nutritious and balanced diet that includes lots of minerals and vitamins is proven to help heal broken bones of all types, including. Therefore, focus on eating lots of fresh produce (fruits and veggies), whole grains, lean meats, and fish to give your body the building blocks needed to properly repair your. In addition, drink plenty of purified water, milk, and other dairy-based beverages to augment what you eat.

  • Broken bones need ample minerals (calcium, phosphorus, magnesium, boron) and protein to become strong and healthy again.
  • Excellent sources of minerals/protein include dairy products, tofu, beans, broccoli, nuts and seeds, sardines, and salmon.
  • Important vitamins that are needed for bone healing include vitamin C (needed to make collagen), vitamin D (crucial for mineral absorption), and vitamin K (binds calcium to bones and triggers collagen formation).
  • Conversely, don’t consume food or drink that is known to impair bone/tissue healing, such as alcoholic beverages, sodas, most fast food items, and foods made with lots of refined sugars and preservatives.
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Medication

The following medications may be considered doctor to relieve acute and immediate pain

The appropriate treatment for a Boxer’s fracture on the initial presentation varies based on whether the fracture is open or closed, the degree of angulation, rotation, and other concomitant injuries. Due to the risk of infection from “fight bite,” even very small wounds should be thoroughly irrigated, and there should be a low threshold for antibiotic treatment.

Surgery

Closed Reduction

Closed reduction is required for a Boxer’s fracture with significant angulation greater than 30 degrees.

  • Analgesia Options – for the procedure include a hematoma block or an ulnar nerve block. Younger children or very anxious patients may require procedural sedation, but this procedure typically is tolerated well without sedation.
  • A closed reduction of a Boxer’s fracture – is accomplished by using the “90-90 method.” The MCP, DIP, and PIP joints should all be flexed to 90 degrees. The clinician should then apply volar pressure over the dorsal aspect of the fracture site while applying pressure axially to the flexed PIP joint. This axial pressure to the PIP applies dorsal force to the distal fracture fragment. The clinician should be able to feel the reduction when it has been achieved. The injury should be immobilized with an ulnar gutter splint, and post-reduction films should be taken to assess for adequate reduction . The fifth metacarpal neck can tolerate angulation of up to 50-60 degrees and management may be continued non-operatively if remains within acceptable tolerances.
  • Surgical Referral – Surgical referral is indicated for fractures that are open, severely comminuted, associated with neurovascular injury, and for fractures with any malrotation. Surgical referral is also appropriate for fractures with significant angulation if the initial provider is unsuccessful in achieving adequate reduction and alignment outside acceptable parameters.  Surgical options include open reduction internal fixation or closed reduction percutaneous pinning.

Boxer’s Fracture Treatment Self-Care at Home

Home care for boxer’s fractures can be divided into care prior to seeing a doctor and care after a diagnosis of a boxer’s fracture is made.

  • The immediate goals of caring for an injured hand are to minimize pain and swelling, minimize the risk of infection of any open cuts, and to prevent further injury caused by an unstable fracture.
  • The best approach to reduce pain and swelling is to apply an ice pack to the injured area. If ice is not available, placing a towel soaked in cold water on the injured hand will work. Elevating the injured hand will also help reduce swelling.
  • An open cut sustained at the time of injury suggests an open fracture-a type of broken bone that is at increased risk for infection and poor healing. All cuts should be washed with soap and water and then covered with a clean bandage immediately to reduce the risk of infection.
  • A key technique to prevent further injury from a fracture is to immobilize the injured hand. This is often best accomplished by holding the injured hand in the uninjured hand. In addition, take care not to use the injured hand to lift objects or perform any task that would place stress on it. Using a broken hand that is not properly immobilized can cause damage to surrounding muscles, blood vessels, tendons, ligaments, and nerves.
  • Home care after the diagnosis of the boxer’s fracture is based on how the doctor treated the hand. Home care includes pain management, cast or splint care, and monitoring for signs of infection.
  • Bones, like many other parts of the body, contain nerve fibers that transmit the sensation of pain. Pain from broken bones is caused by swelling due to injury of the tissues around the fracture site, or by the broken bone moving against the nerve fibers. Pain should lessen once a broken bone is immobilized and movement is prevented. Some degree of pain may still persist. When a doctor writes a prescription for pain medication, it is important to take the medication as prescribed. This will help alleviate pain and will minimize the risk of any unwanted side effects from the medication.
  • Splinting or casting commonly is performed on all boxer’s fractures that do not require immediate surgery. All splints and casts should be kept dry in order to maintain their strength. A complication that can be seen with this procedure is the cast becoming too tight from the swelling of the fracture. When this happens, you may feel pain under the cast or splint. Another sign is numbness or tingling in the fingers on the casted hand. In addition, the finger may become cool to the touch. When this occurs, call your doctor or report to a hospital’s emergency department immediately for evaluation.
  • Infection can occur at an open cut. Wounds should be kept clean and covered until healing is complete. If stitches are used to close a cut, the doctor will provide additional instructions on how to care for the stitches, and when they should be removed. It is important to follow these directions carefully to minimize the risk of infection. Monitor any cuts for signs of infection. Warning signs of infection include redness, red streaking away from the cut, warmth, or swelling around the site of the cut. Pus may also drain from the wound. Any of these signs require immediate evaluation.
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Next Steps

A person with a boxer’s fracture frequently is advised to follow-up with a bone specialist (orthopedic surgeon) or a hand specialist to ensure that the broken bone mends properly. The hand specialist may be either an orthopedic surgeon or a plastic surgeon who specializes in hand injuries.

  • Follow-up should occur within 1 week of the initial injury if there is not a critical amount of angulation. If angulation of the fracture exceeds acceptable levels, follow-up should occur sooner.
  • If a plaster splint is placed in your doctor’s office, or in the emergency department, and you develop increased pain or numbness in your fingers, or if your fingers become cold and blue, then loosen the splint, notify your doctor, and return to the emergency department immediately.

Follow-Up

Boxer’s fractures should be sent for repeat radiographs within one week to assess alignment.

  • Radiographs should be obtained every two weeks following, until clinical and radiographic healing are present, typically between four to six weeks. Even with the adequate reduction, some cosmetic deformity may persist, with loss of the normal knuckle contour.
  • After a short period of immobilization, the passive and active range of motion exercises should be performed to alleviate stiffness of the MCP and PIP joints. Literature supports the early mobilization of these injuries rather than prolonged immobilization. If any loss of function persists after several weeks of these exercises, referral to occupational therapy is warranted.

Complications

Unfortunately, irrespective of chosen treatment modality, metacarpal fractures have complications associated with them, and treating those is essential to achieve good outcomes. Scope for complications is greater with open injuries and those with a soft tissue damage component. The greater the damage to surrounding soft tissues, the poorer the outcome tends to be, and the incidence of complications increases. Conversely, in young and healthy patients, complications are less common.

 Metacarpal fracture complications include:

  • Compartment syndrome – Severe trauma and/or soft tissue injury may result in compartment syndrome of the hand whether or not the injury presents in a closed (as opposed to open) fashion.  Although relatively rare compared to the lower extremities, acute compartment syndrome of the hand should be ruled out in all clinical presentations associated with significant hand soft tissue swelling/deformity.
  • Stiffness – Stiffness is common and often coexists with tendon adhesions. Longer immobilization periods, as well as periosteal stripping and neurovascular injuries, increase the risk of it. Prevention includes using low profile plates, splinting in functional positions, pain control, and early mobilization. In severe cases, tenolysis might be needed to improve the outcome.
  • Malunion – Malunion is the most common complication and results in a deformity, which can be problematic both functionally and cosmetically. Extensors are more likely to be affected than flexors in metacarpal fractures because of bone shortening. Surgery is required to treat malunion if indicated in a particular patient.
  • Non-union – Non-union is a lack of bone healing four months after the injury. It is rare and commonly associated with nerve injury, infection, bone loss, and revascularizing methods of fixation. Diagnosis is made clinically with the help of radiological evidence. It can result from inadequate immobilization, failed fixation, bone loss, and poor tissue approximation. The treatment is a stable fixation with or without bone grafting. Occasionally tenolysis is also required to improve function.
  • Tendon rupture – Plate fixation runs a risk of tendon irritation and in worst cases, rupture. If plates are used, periosteal closure should be done whenever possible to reduce this risk.  Healthcare providers should evaluate extensor tendon function following operative and nonoperative management of these injuries.
  • Infection (including osteomyelitis) – Although metacarpal osteomyelitis is rare, it requires removal of all metalwork, taking cultures from tissues, and thorough debridement. Over 50% of such infections ends in amputation.
  • Cold intolerance – Cold intolerance is a known complication of hand trauma and may affect over a third of patients.
  • Chronic pain – Intra-articular fractures have a slightly worse prognosis, with 40% of patients with metacarpal base fractures reporting chronic pain irrespective of management method. Arthrodesis can be performed to manage this if severe.
  • Instability – Long-term instability is a risk, particularly in thumb base fractures.

References

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