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Sternum or the breastbone refers to the long flattened dagger shaped bone situated along the midline in the center of the chest. It connects to the rib bone by means of tough elastic tissue (cartilage) forming the front part of the rib cage.

An Introduction To The Sternum Or Breastbone

The sternum plays a very significant role in the normal functioning of the body. The sternum is connected to the rib by coastal cartilage to complete the rib cage circle. The rib cage circle thus formed protects the vital organs like the heart, lungs, and major blood vessels from physical damage. [1]

Sternum Fracture

A fracture of the breastbone is called a sternum fracture. The incidence of breastbone fractures is higher in females than in males. A sternum fracture is commonly noted in adults over the age of 50 years. Children are less prone to sternum fractures. [2]

A sternum or breastbone fracture is noted in 5-8% of individuals who have experienced a trauma to the chest. It has been reported that about 60-90% of the sternum fractures occur due to motor accidents. The absence of airbags and failure to wear seatbelts are the most common reasons for sternum fractures in motor accidents. During a collision, the chest of a driver who is not wearing a seat belt suddenly strikes the steering wheel or hits against the hard dashboard, resulting in a breastbone injury. A breastbone injury also can occur when the chest suddenly flexes. [3]

Other causes of sternum fractures can include occupational or sports-related injuries. Research studies have shown that people who work in high-rise construction sites and warehouses are at a risk of a sternum fracture due to falls. People participating in sports such as wrestling, football, hockey, martial arts, weightlifting, and boxing are also at risk of sustaining a sternum fracture, owing to falls or direct blows to the chest. The risk of a sternum fracture due to falls or trauma can increase when the bone structure is weakened due to certain underlying disorders, such as osteoporosis. [4]

Signs And Symptoms Of A Sternum Fracture

The signs and symptoms of a breastbone fracture include the following [5]:

  • A crunching sound or grinding noise at the site of the injury.
  • Bruising, tenderness and inflammation over the fracture or chest site.
  • Pain in the chest region.
  • Breathing difficulty or pain in the chest when one coughs, laughs or sneezes.
  • Sudden contraction of the muscles (muscle spasm).
  • A deformed appearance of the rib cage.

Breastbone fractures associated with rib fractures can result in serious internal injuries to the heart and lungs. The features of such cases are dependent upon the type of organ involved and the severity of the injury to the underlying organ.

Diagnosis Of A Sternum Fracture

The diagnosis of a breastbone fracture is based on a history of chest trauma, physical examination findings, and imaging techniques.

The doctor feels the breastbone to identify any changes in the shape or discontinuity in the structure. The chest region is also examined for deformations, bruising, or swelling. 

Plain X-rays of the upper chest determine the severity and location of the sternal fracture. In case of severe injury, specialized imaging studies such as CT and MRI are done to detect any other associated injuries. 

The doctor particularly looks out for the presence of internal injuries such as those to the lungs and the heart. Other additional tests may also be advised depending upon the suspected organ or structure injured. [5]

Dangers Of A Sternum Fracture

We mainly associate sternum fractures with the possibility of injuries to the heart and lungs. Other related injuries that are noted to occur in individuals with a fracture of the breastbone include damage to blood vessels in the chest, injury to the abdominal organs and vertebral fracture.

Breastbone fractures are also generally accompanied by rib fractures. The prevalence of death from sternum fracture associated injuries is estimated to be about 25-45%.

Since the rib cage and the sternum cover vital organs like the heart and lungs, chest injury can result in a life-threatening situation, due to injuries such as punctured lungs or a ruptured aorta.

Injuries related to a sternum fracture include [5]: 

  • A bruise to the heart (cardiac contusion)
  • Blood in the chest cavity (hemothorax)
  • A bruise in the lung (pulmonary contusion) 
  • Aortic injury 
  • Rib fracture 
  • Spinal cord injuries 

Studies have shown that 10% of breastbone fractures are associated with spinal fractures and about 20% of breastbone injuries are related to rib fractures.

Other complications arising from a breastbone fracture include:

  • Infection the in bone (osteomyelitis)
  • Disease of the lung (pneumonia)
  • A collapse of lungs

Breastbone fractures cause damage to the blood vessels or the ligaments around the ribcage in many instances. 

Incorrect healing or failure of bone fusion can result in a deformity of the bone. 

In some cases, the nonunion can compress the blood vessels or nerve cells, leading to a condition referred to as thoracic outlet syndrome.

Read More: Lisfranc Fracture – Commonly Missed Diagnosis

Sternum Fracture Treatment, Prognosis, And Prevention

Sternum fracture treatment

The treatment of a sternum fracture is dependent upon the severity of the fracture and the type of organ involved (if any). Life-saving measures are initiated if severe or life-threatening injuries to the lungs, heart or blood vessels are noted. [5]

In the absence of such injuries or, once the condition of the affected individual is stabilized, other treatment measures are started.

The supportive treatment for sternum fractures includes rest for about 10-24 weeks and applying a cold compress to the injured region to help reduce inflammation. However, care should be taken not to apply pressure. 

Individuals suffering from sternal fractures are advised not to perform any actions such as lifting, carrying, or pushing heavy objects, and overhead work until it is healed. 

Patients can take medications to reduce pain and inflammation. 

While the requirement for surgery in sternum fracture cases is quite low, it may be needed when large fractures or involvement of underlying organs are included.

Patients with isolated sternal fractures generally require short admissions to hospital for pain control and most of them recover completely over a period of 9-12 weeks with an average of 10.4weeks. Two-thirds of these patients require only analgesia and their predominant symptom is chest pain during this period. [5]

Prognosis of sternum fracture

Breastbone fractures take about 10 to 24 weeks to heal until a complete recovery is achieved. During this period, doctors observe if there is any chest pain. Nonunion of breastbone fracture is rarely seen.

Prevention

The majority of sternum fractures are caused due to traffic collisions. Wearing seat belts can prevent breastbone fractures in such situations. 

Wearing protective equipment while involved in contact or high impact sports and while working at high-rise construction sites can prevent a sternum fracture in these groups of individuals. Lifting or pulling heavy equipment at work without proper protective gears should be avoided.