A complete dislocation of the sternum, or breastbone, is rare due to its strong anatomical connections. While a true dislocation is rare, other injuries and conditions affecting the sternum or surrounding areas are more common and cause similar uncomfortable symptoms. Understanding the sternum’s structure helps clarify why certain injuries are more prevalent.
The Sternum’s Structure and Stability
The sternum is a flat, elongated bone in the center of the chest, forming the front of the rib cage. It consists of three main segments: the manubrium, the body, and the xiphoid process. The manubrium, the uppermost part, articulates with the clavicles and the first pair of ribs. The longest section, the body, connects to the cartilages of the second through seventh ribs. The xiphoid process, the smallest and lowest part, varies in size and shape.
The sternal segments are joined by strong, relatively immobile cartilaginous joints. Ribs connect to the sternum via costal cartilages, allowing slight flexibility during breathing while protecting vital organs. Ligaments and surrounding muscles reinforce these connections, providing stability. This design prioritizes protection and structural support over extensive movement, making true sternal dislocation unlikely.
What Can Happen Instead of a True Dislocation
Given the sternum’s stability, other conditions are often mistaken for a “dislocated sternum.”
Sternal Fractures
Sternal fractures are frequent injuries, often resulting from direct blunt trauma, such as car accidents where the chest impacts a steering wheel or from seatbelt injuries during deceleration. These fractures typically cause localized pain that intensifies with deep breathing, coughing, or movement. In some cases, a visible deformity or a palpable “step” may be present at the fracture site.
Manubriosternal Dislocation
Manubriosternal dislocation or separation, though rare, is the closest injury to a true sternal dislocation. It occurs at the joint between the manubrium and sternal body, usually due to severe force. This injury can lead to instability and significant pain at the upper part of the sternum.
Costochondritis
Costochondritis is another common cause of chest pain that can be confused with a sternum injury. This condition involves inflammation of the cartilage connecting the ribs to the sternum. It causes sharp, aching, or pressure-like pain, typically on the left side of the breastbone, worsening with movement, deep breathing, or direct pressure. Unlike fractures or dislocations, costochondritis is usually non-traumatic and is often self-limiting, resolving on its own over time.
Xiphoid Process Issues
Issues involving the xiphoid process, the small cartilaginous tip at the bottom of the sternum, can cause localized pain. This pain, sometimes called xiphoidalgia or xiphodynia, often arises from trauma, such as incorrect cardiopulmonary resuscitation (CPR), or from repetitive straining of the torso. It can manifest as tightness, pressure, or sharp pain in the lower sternum region, potentially radiating to the chest or abdomen.
Recognizing Sternum Injuries
Symptoms of sternum injuries or related conditions generally involve chest pain and discomfort. Localized pain, which can be sharp, aching, or pressure-like, is common. This pain often worsens with deep breathing, coughing, sneezing, or torso movements like twisting or bending. Swelling, bruising, or tenderness over the sternum may also be present, depending on the injury.
With more severe injuries, individuals might experience shortness of breath. This difficulty is often due to pain limiting deep breaths, though lung complications can sometimes occur. Deformity, such as a lump or step, can indicate a displaced sternal fracture. If severe pain, difficulty breathing, or a visible deformity is present, or if chest pain is accompanied by symptoms like spreading pain to arms, neck, or jaw, sweating, nausea, or lightheadedness, immediate medical attention is necessary to rule out serious conditions, including a heart attack.
Diagnosis and Management of Sternum Injuries
Medical professionals diagnose sternum-related issues through a comprehensive approach that typically begins with a detailed patient history and physical examination. During the physical exam, the doctor assesses for swelling, tenderness, and palpable deformities. Imaging techniques are often used to confirm a diagnosis and evaluate the extent of the injury. A lateral sternal X-ray can identify fractures by providing a side profile of the bone.
Computed tomography (CT) scans are frequently employed and are considered highly sensitive for detecting sternal fractures, providing detailed views of bones and joints. Ultrasound can also effectively detect sternal fractures and associated bruising. For soft tissue injuries, such as cartilage or ligaments, magnetic resonance imaging (MRI) may be used. These imaging studies also help rule out injuries to the heart or lungs.
Management of sternum injuries largely depends on the specific condition and its severity. Many sternal issues, including most fractures and costochondritis, are treated conservatively with rest, ice, and pain relievers like NSAIDs. Physical therapy plays a role in recovery, focusing on gentle range-of-motion exercises, breathing exercises to prevent lung complications, and strengthening the chest and upper body muscles. Surgical intervention is rarely needed for sternal fractures, typically reserved for severe cases involving unstable fractures, significant displacement, or persistent pain unresponsive to conservative measures. A medical evaluation is important for an accurate diagnosis and appropriate treatment plan.