The xiphoid process (or xiphisternum, metasternum) is the third segment of the sternum, commonly referred to as the breast bone, in human anatomy.
It is a small section of bone located at the base of the sternum at the 10th thoracic vertebrae.
It is most commonly triangular in shape and may also features a small perforation within its structure.
In some cases, the XP will be bifurcated. This results in xiphoid process developing with two branches instead of a single point.(1)
It is considered a normal variant in structure and is often found to follow genetic familial lines.
Due to its physical form, the word xiphoid is derived from the Greek word xiphos, meaning “straight sword.”
The xiphoid process is also known by other names including;
• the ensiform
• processus xiphoideus
• or xiphoid appendix
This section of bone protrudes downward from the second portion of the sternum called the manubrium.(2)
The two sections are connected by the xiphisternal joint which, by midlife, fuses the two portions together and creates an immobile joint.
The Function
Initially made of pliable cartilage, the XP remains flexible from infancy through to young adulthood before inevitably calcifying with age through a process known as ossification.
The initial flexibility allows for proper growth and physical development through childhood and adolescence while also providing a level of protection to the development of certain internal organs, such as the heart and the esophagus.
At times, the protrusion is visible under the skin of infants and later recedes into the body.
Generally, the ossification of the xiphoid process is complete around the age of 40 resulting in the rigid structure it will maintain throughout the rest of a person’s lifespan.(3)
The XP functions as an anchor point for various muscles, most notably the diaphragm, the transverse thoracic and the rectus abdominis.
Additionally, it can serve as a physical landmark to other critical portions of the human anatomy such as the lower margin of the heart of the superior end of the liver.
It is also used as a guide in ensuring medical professionals position themselves properly when performing cardiopulmonary resuscitation, or CPR.
Improper hand placement while performing CPR can fracture the xiphoid process and, in extreme cases, break it free from the rest of the sternum.
This poses a particular risk as the floating piece of bone may then cause damage to other areas, including;
• the heart
• liver
• or lungs
The broken piece can also lead to a puncture in the diaphragm.
Xiphoid Process Pain
When pain is felt in the area of the XP it is known as xiphoid syndrome, xiphoidalgia or xiphodynia.(4)
The pain associated with xiphoidalgia is often characterized as sharp and deep.
Generally, the associated pain worsens when the area is physically compressed as well as with certain forms of movement, such as the bending or twisting of the torso.
Additionally, the pain may radiate to other areas of the body. Pain may be felt in the chest, back or other thoracic areas. In some cases, pain may also be experienced in the arms or neck.(4)
Depending on which areas are affected by the pain, the symptoms may mimic the pain symptoms commonly associated with a heart attack.(5, 6)
This may lead to the condition being under-diagnosed as more serious conditions are investigated.
Aside from heart disease, there are also similar symptoms present in the diagnosis of gallbladder disease and various forms of bone disease.
The intensity of the pain may vary. While some may find the pain tolerable, it may be unbearable for others.
In extreme cases, the severity of the pain experienced may lead to those experiencing it to become nauseated.(4)
Potential Causes of Pain
Pain may be caused by a variety of factors. While physical trauma is the most common source of the irritation, it is not the only known cause.
Some may experience xiphoid process syndrome due to other inflammatory conditions, while others may be caused by a physical malformation of structure.(4)
Additionally, the inflammation and pain associated with XP syndrome may occur spontaneously, with no easily identifiable underlying condition or injury.(4)
Injury
The most common cause of pain in the region of the xiphoid process is the result of a physical injury.(7)
This can include compression caused by a collision with an object, such as the impact of a steering wheel in a car accident, or when the area is impacted by a moving object, as may occur in various sporting activities.
Though the area is designed with some mobility, high amounts of pressure can result in a fracture.
It is also possible to injure the area when lifting a heavy object, or when the body is twisted.
This may occur when attempting a physical act that is not normally performed by the person, or within the realm of normal day-to-day activity.
Injuries of this nature may also result in localized swelling which can lead to additional tenderness when the area is touched.
A final cause of physical injury to the area can occur when suffering from a cough.
The act of coughing can be somewhat traumatic, as a large number of thoracic muscles are in use to assist the lungs with the rapid expansion and contraction required to attempt to rid a foreign object or substance.
This sort of injury is more common in conditions that result in a long-term cough, such as emphysema, though can also occur during an acute respiratory illness.
Xiphoid Process and GERD
Another common cause of discomfort around the XP is gastroesophageal reflux disease or GERD.
A condition involving stomach acid flowing back up through the esophagus, GERD can produce pain in the same regions as XP.
As the acid flows up the esophagus, it becomes irritated and inflamed. This pain can be similar to that of xiphoid process syndrome based on where the esophagus is located within the body.
Since the pains may be similarly located, it can be easy to mistake the symptoms of one condition for the other.
It is also important to note that having one condition does not necessarily lead to the other, though it is possible to experience symptoms of both conditions simultaneously.
Changes in Body Weight
Some cases of xiphoid process pain have been noted in persons who have undergone significant weight loss.
As a person gains weight, additional fat will be deposited in the abdomen. This can cause the organs to shift and the ribcage to expand, especially in cases of medical obesity.
This can result in additional outward pressure against the ribs and sternum, ultimately resulting in pain.
When the same person loses the excess fat, the internal organs may shift again.
The ribcage may continue to protrude outward even as the stomach area becomes smaller, resulting in irritation around the xiphoid process.
Often, this pain subsides with little or no treatment, especially at the body adjusts to its new size.
Treatment
A diagnosis of xiphoid process pain is not necessarily indicative of a more serious health condition and can be treated on its own when medically necessary.
It is more common in those with an enlarged xiphoid process as well as those who have experienced a previous injury to the area.
In most cases, the pain will subside on its own, with or without treatment.
Though the pain may last only a few minutes, it is possible for the pain to persist for months resulting in a condition referred to as hypersensitive xiphoid syndrome or xiphoid syndrome.(8)
Typical treatment for xiphoid syndrome begins with analgesics or nonsteroidal anti-inflammatory drugs, also known as NSAIDs.(9)
This treatment course is considered to be fairly low risk in the medical community.
It is important to evaluate any other medical treatments that may be in use with your physician to avoid potentially dangerous interactions.
This includes any other prescribed or over-the-counter medications as well as any dietary supplements in use.
The application of heat may be recommended as part of the treatment course as an additional way to provide relief from the associated discomfort.
Further, physical therapy may be prescribed to assist in maintaining mobility and strength within the check wall muscles.
If initial treatment does not provide relief from the pain of xiphoid syndrome, additional measures may be considered.
Some find relief through the use of an elastic rib belt. As the belt applies pressure to the sternum, pain symptoms may lessen.(10)
The use of opioid medications may be recommended if other pain relievers have been found ineffective.
Finally, an injection of corticosteroids or lidocaine may be administered into the xiphisternal joint to provide relief.
Under specific circumstances, surgery may be required if the pain is found to be caused by a structural abnormality.(7)
Such an abnormality may occur naturally, but can also be caused by the improper healing of a previous injury.
In cases involving a broken xiphoid process, the pull of the abdominal muscles on the broken piece of the structure may lead it is sit lower in the abdomen than it would otherwise.(11)
A new bone structure is formed between the broken piece and the rest of the sternum as part of the healing process.
The elongated structure of the xiphoid process, once healing is complete, may increase the likelihood of physical discomfort in the area.
Additionally, should the xiphoid process break away from the rest of the sternum resulting in a free-floating bone fragment, it may need to be removed if it poses a risk to surrounding tissues.
Conclusion
It is important to note that some medical treatments and all surgical procedures are associated with a level of risk.
Often, your physician will recommend a treatment because they feel the potential positive outcome is worth the risk involved based on the severity and the frequency of your symptoms.
Be sure to speak with your physician about any concerns you may have regarding your treatment.
References
(1)https://en.wikipedia.org/wiki/Xiphoid_process
(2)www.brighthub.com/science/medical/articles/57775.aspx
(3)Abnormal Skeletal Phenotypes: From Simple Signs to Complex Diagnoses Alessandro Castriota-Scanderbeg, Bruno Dallapiccola Springer Science & Business Media 2006
(4)http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2045657/
(5)http://www.ncbi.nlm.nih.gov/pubmed/9517698
(6)http://www.ncbi.nlm.nih.gov/pubmed/26073251
(7)http://occmed.oxfordjournals.org/content/early/2013/12/09/occmed.kqt132.full
(8)http://www.nejm.org/doi/full/10.1056/NEJM195510062531403
(9)“healthfixit.com/xiphoid-process-pain/#treatment-for-xiphoid-process-pain
(10)Waldman SD, Atlas of Uncommon Pain Syndromes, Elsevier Health Sciences 2013, p 193-194
(11)http://www.sciencedirect.com/science/article/pii/S1572346105000115
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