A popping or cracking noise emanating from the sternum (breastbone) is usually associated with the joints between the breastbone and ribs. These bones are connected to each other by a length of cartilage (costal cartilage) that extends from the rib and attaches to the sternum.
The cartilage of the first seven ribs articulate with the sternum at the sternocostal joints. These cartilages also articulate with the ribs at the costochondral joints. The clavicle also articulates with the sternum at the sternoclavicular joint although this is less likely to be associated with any audible clicking. The popping or cracking noise may be accompanied by breast bone pain, tenderness and/or joint swelling.
Why do the sternal or rib joints click?
The exact mechanism of popping or cracking of any joint is not known. It may be due to the ‘snapping’ of ligaments or tendons, gas bubbles released from the joint fluid (cavitation) or partial dislocation (sublaxation). At times a grating noise may be heard, like two rough surfaces scraping against each other. This may occur if there is erosion of the bone or joint lining which occurs as a consequence of certain types of arthritis that persist over a long period of time.
Popping joints are not usually considered to be a medical problem unless there is pain, swelling or limited mobility associated with the cracking or clicking. In these cases, inflammation of the joint is likely and the popping noise may settle, along with the pain and swelling, over time or with the use of anti-inflammatory drugs.
The popping may occur spontaneously but usually occurs with movement like when breathing deeply or stretching the arms wide. The popping may sometimes relieve the pain, if present. In some cases, stress may aggravate the popping sound and breast bone pain.
Causes of Popping, Cracking Sternum or Ribs
Some of the causes of the clicking of the sternum or rib may include :
- Trauma. Injury to the chest area, example – assault, falls or car accident injuries where there is impact with the steering wheel.
- Physical strain. This may be seen in excessive weight lifting (bench pressing) or other activities that put pressure on the chest wall, its muscles and bones. A person who supports their body weight on one hand or elbow over long periods may transfer the weight across the costal cartilage and thereby strain the joint possibly leading to inflammation or sublaxation.
- Costochondritis is the inflammation of the costal cartilage and usually affects the fourth to sixth ribs. This may be caused by infections, postoperatively (like in cardiothoracic ‘open heart’ surgery) or after repeated minor trauma and/or physical strain. Pain and tenderness is usually present although swelling is not typically evident.
- Tietze’s syndrome is similar to costochondritis but usually affects the second and third ribs and more commonly occurs in young girls. Apart from pain, there is also detectable swelling. It is usually caused by the repeated minor trauma or physical strain, including persistent coughing or repeated vomiting.
- Muscle spasm may also cause sublaxation of the joint as the degree of flexibility is limited due to ‘tight’ muscles. This is usually accompanied by chest pain. Refer to the article on Muscle Chest Pain.
- Osteoarthritis or rheumatoid arthritis. These types of arthritis do not commonly affect these joints or cause clicking but it may be possible in widespread cases of arthritis. Joint degeneration due to chronic arthritis could cause a grating sound.
- Calcification of the costal cartilage.