The smallest and lowermost section of the breastbone or sternum is known as the xiphoid process. This bony structure forming the tip of the sternum is also referred to as ‘metasternum’ or ‘xiphisternum.’ It is sometimes called the ensiform process. At birth, it is a cartilaginous projection, slim in shape and somewhat triangulated in the form. It gradually ossifies and merges with the sternum during adulthood.
During clinical case studies and observations, it serves as an anatomical landmark in the torso. It is highly susceptible to getting damaged or splintered if a CPR (cardiopulmonary resuscitation) is not conducted scientifically or appropriately.
The etymology can be traced to ‘xiphos’ which is a Greek word meaning ‘straight sword.’ Anatomical examination of the breastplate bone clearly shows that its extremity (the margin or tip) is shaped roughly like the edge of a straight sword. The Latin expression ‘processus xiphoids’, when translated into English, stands for ‘xiphoid process.’ Alternatively, the root meaning of the ancient Greek and classical Latin terms for bone is also sword-like.
Pinpointing the location at the end of the chestbone, it lies in the middle of the vertebral column. The ‘xiphisternal joint’ (xiphisternal synchondrosis), the junction where the body of the sternum meets the xiphoid is situated inferiorly opposite to T9 vertebra. The edge of xiphoid process is at the same level as the T10 vertebra.
The xiphisternum extends from the 9th rib pair of thoracic vertebra just at the junction where this rib meets the sternum. A small orifice or opening marks the extension, starting from its uppermost end where it is also at its broadest. It is linked here to the body of sternum by a partially movable sinewy joint called syndesmosis. Looking upwards from the tip of the sternum, the xiphoid process comes first, above it lie the body, and the manubrium is the topmost section.
Xiphoid Process Structure
Structurally, the xiphoid appendix is cartilaginous from birth through to the teenage years, ossifying fully in the superior part by the time one becomes an adult. The structural form of the ensiform process are enumerated below:
- Anterior plane (Front): Attached partially to the Rectus abdominis muscle and the frontal costoxiphoid ligament on both the ends
- Posterior surface (Back): Linked to the backside of the costoxiphoid ligament and a few fibers of the diaphragm as well as to the Transversus thoracis.The inferior part of the abdominal diaphragm which also lies in the posterior plane is associated with the liver’s left lobe, a bit on the falciform ligament’s left side.
- Superior (Upper): Its articulation is with the inferior part of the body of the sternum. While at the front of the superior section, on either side is a smoothened groove that partly accepts the 7th rib pair’s costal cartilage
- Inferior (Lower): It articulates with the linea alba via the extremity which is pointed.
- Lateral Surfaces: They are connected to the abdominal muscles’ aponeuroses.
Formation, Growth, & Development
The metasternum or xiphoid extension which originates as a cartilaginous structure is at the right from birth. As the newborn grows into an infant, its tip not only becomes visible but upon touching (just beneath the sternal notch) feels like a lumpy mass. During inception, it is a structure composed of hyaline cartilages that remains in this state until childhood.
The xiphoid process should fuse with the body of sternum before one attains the age of thirty. Normally, it should join with the body via a synarthroses (an immovable fibrous joint) between the ages of 15 and 30. However, this fusion more often than not takes place when the individual is forty years old.
Nevertheless, on very rare occasions, it remains disunited or dissociated. The ossification process, in which the lowest segment of the sternum transforms into a bony structure commences after infancy. But the development process of bone formation progresses very slowly and by the time the transformation is complete one is in his or her forties.
It could be broad and slender appearing forked or split, arched, and even having perforations. Now, these morphological variations normally tend to be genetic or hereditary. It is worthwhile to note that these disparities do not in any way have a bearing on its functioning.
Additionally, the deviations from the norm, as far as its shape, size, and structure is concerned do not lead to any health hazards. Of all the numerous variances in its shape, the most common include:
- Forking in the middle of the lower end, bifurcating into right and left branches
- Perforation or hole characterized by a tiny opening
Xiphoid Process functions
The xiphoid process serves as a significant and strategic junction for a lot of important muscles.
- Articulating Point: For instance, it is one of the articulating points for the diaphragm (rounded skeletal muscle which forms the basilar section of the ribcage). It separates the abdomen from the ribcage for promoting respiration.
- Offers Support: Two vital abdominal muscles, ‘transverse abdominis’ and ‘rectus abdominis’ play a crucial role in expanding and compressing the abdomen transmit through the xiphisternum. These muscles offer backup to the spinal muscles during the performance of arduous activities and also assist in breathing.
- Tracing Pericardium: It also functions as a significant landmark for tracing the pericardium (the two-tiered serous membrane that encircles the heart) while performing pericardiocentesis on a patient suffering from cardiac tamponade. The pericardium has to be aspirated with a syringe via the xiphoid for drawing out fluid for assay.
- Bridge: It also forms a bridge with the solar plexus’s or celiac plexus cartilage (complex mesh of nerves situated in the abdominal cavity, at the backside of the stomach’s fundus).
- Linkage: The costal cartilages of the rib pairs of the thoracic cage are also linked with it indirectly.
The xiphisternum as a single, fused, and unified bony outgrowth has tremendous clinical importance. Its significance can be gauged from the following medical conditions:
- Serves as an important marker during the administration of cardiopulmonary resuscitation. Due care should be taken while carrying out CPR as applying too much pressure during chest compressions could lead to its breakage, ultimately causing diaphragmatic lacerations or perforations. The liver getting punctured leading to fatal hemorrhaging is the worst possible scenario.
- Individuals above 40 years in whom the ossification of the metasternum remains incomplete might be conscious of this condition, misconstruing it as some sort of aberration
- Sometimes soreness and pain felt in this area as well as in the remaining section of the breastbone could be a sign of xiphoidalgia or xiphodynia, a very rare musculoskeletal disorder. Many signs and symptoms of this condition are similar to those of several thoracic and abdominal disorders that could create a lot of confusion.
- Used as a passage for conducting pericardiocentesis, a method whereby fluid is drawn out of the pericardium for temporarily stabilizing a patient suffering from pericardial tamponade
Conditions associated with the Xiphoid Process
1. Xiphodynia or Xiphoidalgia
Xiphodynia variously referred to as ‘Xiphoidalgia’ or ‘Xiphoid Syndrome’ signifies or denotes pain in the xiphoid. The sensation is felt as a consequence of soreness, tumescence or protrusion of the bony projection.
Swelling, tenderness or protuberance of the structure (most common causes of xiphodynia) could result from the following conditions:
- In case an individual becomes too obese or loses excess weight, an inordinate disproportionateness of the physique is created. This exerts pressure on the xiphoid process and makes the metasternum to bend.
- Performing strenuous exercises for a long duration or lifting heavy objects on a regular basis also creates intense pressure on it and causes it to stick out or bend.
- Fractured, splintered or damaged structure causes severe cardiac stress or trauma. Damage or fracture could occur because of:
- Improper CPR application
- Whiplash injuries caused by car accidents
- Participation in contact sports
- Accidentals falls
Following are some rare causes of xiphoidalgia:
- Acid reflux caused by GERD (gastroesophageal reflux disease)
- Gorging or overeating
- Straining the torso on a recurrent basis
Signs & Symptoms
- Discomfort in the chest
- Tender or sore chest
- An excessive backache
- Soreness in the shoulders
- A feeling of discomfort in the region surrounding the stomach or above it
- Excessive vomiting
- Excruciating pain in the shoulders and chest
Xiphoidalgia, by and large leads to shooting pain in the shoulders and back. The pain which originates in the xiphisternum spreading to anterior and posterior regions. An imaging or radiological assay usually confirm its diagnosis. Other diagnostic methods include ultrasound scan and x-ray.
Though it is easily diagnosable, the disorder is remarkably rare. Owing to the condition’s uncommonness, its occurrence is usually either overlooked or ignored or diagnosed incorrectly leading to further complications.
The pain can be extreme or mild and the treatment depends upon the severity or intenseness of pain.
If it pains mildly, then non-steroidal anti-inflammatory drugs (NSAIDs), analgesics, and anodynes are normally taken. One needs to take both NSAIDs and anodynes at the same time as the former helps arrest inflammation and reduce its intensity while the latter offers relief from pain.
Medical professionals generally prescribe opioids like morphine, codeine, hydrocodone, and oxycodone as second-line therapy when analgesics do not work. However, only consume those opioid drugs prescribed by a registered medical practitioner. Alongside opioids, one can resort to hot and cold therapies for alleviating the pain and getting relief.
It helps in relaxing the stiffness or tightness in the muscles and joints around the sternum or substernal areas. On the other hand, applying cold compresses and packs aids in mitigating numbing or radiating pain. This also checks and reduces tenderness or swelling. Though a patient can take advantage of heat and ice therapies on a DIY basis, it is always better to engage a professional.
Corticoids or local anesthetics
If none of the above methods or drug therapies prove effective, the cause of extreme pain could be ascribed to a deep-seated problem or condition, like a fracture or crack. In such situations, the physician usually recommends syringing corticoids or local anesthetics straight into Xyphoid. It helps in reducing swelling and decreasing body’s immune response. Since corticosteroids or corticoids contain very potent chemicals, the side-effects of administering these steroid-based hormones could often turn out to be disastrous, even life-threatening. For instance, the side-effects could lead to gastrointestinal perforation or pneumothorax, and both these infections could turn fatal.
Another very practical and safe treatment is rib belts and abdominal supports. Rib belts are mainly used for expediting the healing a fractured sternum (including the ensiform process) or ribs either naturally or following a bone fracture repair surgery. These belts have an elastic framework with loop closures and front hooks to furnish supporting pressure to the upper and middle back as well as the ribcage if the latter is injured. Sometimes abdominal supports are used along with rib belts for supporting and compressing the core muscles during xiphoid process herniation.
In case all the aforementioned therapies are in vain, the only treatment is removing the sternum appendix surgically. Xiphoidectomy or the surgical resection of the xiphisternum is the last line of treatment for managing xiphoid syndrome.
2. Fractured or Broken Metasternum
The tapering metasternum is free floating at its tip and unprotected by the ribcage making it somewhat vulnerable to injuries and fractures.
It is liable to breaking or getting severely damaged during a whiplash injury that inflicts a heavy and sudden blow to the torso, particularly in the chest. It may be due to a vehicular mishap, accidental trip when one falls flat on his or her face or at some stage of CPR. The sudden forced snapping causes it to perforate the diaphragm and pierce its way through the liver. This eventually results in traumatic hepatic hematoma which could be fatalistic.
Signs and Symptoms
- Intolerable pain in the epigastrium and chest
- Bloating in the epigastric region
- Breathing difficulty owing to the diaphragm’s perforation
- Cramping of the abdominal muscles connected to this bony projection including the rectus abdominis, transverse abdominis, and linea alba
- Shoulder pain
An x-ray, ultrasound or MRI scan can reveal a fractured or splintered ensiform process.
- Self-healing: The end segment of the sternum tends to heal on its own and becomes fixated with the body. The fractured structure heals thoroughly within six weeks.
- Rib Belts & Physiotherapy: Wearing a rib belt together with abdominal support, taking light meals, and undergoing physiotherapy speeds up the healing process. One can opt for a specialized surgical procedure for an accelerated recuperation.
- Surgery: A sophisticated surgical instrument known as ‘Talon’ is used for performing the operation. The surgery has to be carried out with extreme care as even the slightest oversight or inadvertence could punctuate the liver. This eventually leads to internal hemorrhage.
Morgagni a hernia or retrosternal diaphragmatic hernia
Retrosternal diaphragmatic hernia, sometimes referred to as retrosternal diaphragmatic hernia is an extremely rare hereditary disorder. The herniation is parasternal or retrosternal, ascribable to congenital anterior diaphragmatic imperfection. The herniation originates and progresses via the ‘foramen of Morgagni.’
The foramen of Morgagni develops (sandwiched between diaphragm and xiphoid) in individuals whose diaphragms do not have sternal slips.
Signs & symptoms
- Unclear clinical manifestations comprising respiratory complications like chest pain and dyspnea (difficulty in breathing)
- Gastrointestinal problems including vomiting and nausea
Diagnosis & Treatment
This congenital diaphragmatic defect can be easily detected through an X-ray, ultrasound or CT scan. Morgagni Hernia can be repaired through minimally invasive laparotomy or thoracotomy procedures.
Xiphoidectomy: Surgical Resection of the Xiphoid Process
Xiphoidectomy is performed when all other viable options to get rid of xiphodynia prove ineffective. This surgical process is also carried out to prevent a fractured metasternum from perforating vital internal organs including the stomach and liver. Moreover, complicated surgical procedures related to the epigastrium or the upper abdomen cannot be carried out successfully if the epigastric region is not exposed fully.
To have unhindered access to the superior abdominal region, carrying out xiphoidectomy becomes indispensable.
- For conducting the surgery, the orthopedic surgeon makes an incision from the superior or lower end of the xiphoid, starting from the midline and going down to the tip. A thick lump of fat is separated from the posterior rectus sheath, and the xiphoid process is uncovered with a self-retaining retractor.
- After that, the bony outgrowth is dissected and severed from the sternum through electrosurgical dissection. High-voltage electrocoagulation current is used for cutting and detaching to minimize bleeding from several arterial interface points.
The operated area remains tender and swollen for a few days, following the surgery, and the patient is usually able to continue with normal lifestyle within 6-8 weeks.