What is Sternoclavicular Joint Infection?
The sternoclavicular joint is a special type of joint that connects the skeleton of the upper limb to the main part of the skeleton. This joint is formed by the big, inner-side bone of the collarbone connecting with the top part of the sternum and first rib’s cartilage, providing little bone support. Inside the joint, there’s a strong, fibrous cartilage disc that offers structural support and helps prevent the collarbone from moving too far inwards. Further support is given by a strong ligament and a protective layer around it, known as a capsule.
The sternoclavicular joint is primarily held in place by two ligaments at its front and back. Despite these measures, the joint is quite flexible and can move over 30 degrees sideways and upwards-downwards, and rotate over 45 degrees. It acts quite similarly to other slightly movable joints like the one at the base of the spine and between the pelvic bones.
Blood supply to the joint is provided by branches of the suprascapular and internal thoracic arteries. The sternoclavicular joint is innervated, or provided with nerves, by the nerve supplying the muscle beneath the clavicle, and the inner-side nerves of the suprascapular area.
Infections in the sternoclavicular joint are rare, making up less than 1% of all bone and joint infections. Such an infection is usually seen in people with overall poor health or other illnesses like diabetes, those who use intravenous drugs, have weakened immune systems, or have rheumatoid arthritis. Even though rare, it is vital to diagnose and treat this condition quickly to prevent its spread into the important blood vessels behind it and into the chest cavity.
What Causes Sternoclavicular Joint Infection?
Ross and his team studied 180 cases of an infection in the joint between the sternum (the breastbone) and the clavicle (the collarbone), known as septic arthritis. They found that the bacteria Staphylococcus aureus was the most common cause, responsible for 49% of the cases. This was followed by Pseudomonas aeruginosa (10%) and Brucella melitensis (7%).
In a similar study looking at infections in the sternoclavicular joint amongst heroin addicts, Brancos and his team found the same two most common culprits: S. aureus and P. aeruginosa.
Then, in 2015, Jain and his team described an unusual cause of these infections: tuberculosis (TB). They reported a small number of cases (9 men and 4 women) where the cause of septic arthritis in the sternoclavicular joint was found to be secondary to TB.
Risk Factors and Frequency for Sternoclavicular Joint Infection
Septic arthritis of the sternoclavicular joint is a rare condition, accounting for less than 1% of all bone and joint infections. However, among people who use intravenous drugs, it’s responsible for 17% of septic arthritis cases. It’s most commonly found in men between their forty’s and fifty’s. Some reports show that 73% of these infections occur in men, with an average age of 45. It’s also worth noting that in many cases, no clear risk factor for the infection can be identified. A report featured 13 cases where eight men got the infection, with an average age of 37 years.
Signs and Symptoms of Sternoclavicular Joint Infection
Understanding a patient’s full medical background is crucial when dealing with conditions that could affect the sternoclavicular joint, as many of these conditions are systemic, i.e., they impact the body as a whole. The doctor should inquire about any family history of sternoclavicular arthritis, any intravenous drug use, as well as signs like intermittent fever, chills, night sweats, and fatigue. If a patient reports pain near the sternoclavicular joint, or along the inner collarbone, and has a history of high-risk factors or systemic complaints, this should alert the doctor to a potential infection.
An infected sternoclavicular joint will likely appear swollen, warm, sore, and red during a physical examination. The patient will feel pain when direct pressure is applied to the joint and when moving the shoulder on the same side. Usually, arthritis caused by infection will afflict one sternoclavicular joint, whereas conditions like rheumatoid arthritis tend to affect both joints at once. Changes like fluctuation, joint movement, unevenness, and bony enlargement should be noted. An uneven sternoclavicular joint might suggest dislocation, which could require emergency surgery if the joint is positioned at the back and negatively affecting blood flow or nerve function.
Testing for Sternoclavicular Joint Infection
If you’re suspected to have an orthopedic infection, your doctor will usually arrange for tests to check for elevated levels of white blood cells, erythrocyte sedimentation rate (a test that measures how quickly your red blood cells settle at the bottom of a tube, which could indicate inflammation), and C-reactive protein (a protein that increases in your blood when there’s significant inflammation in your body). However, these markers can also increase due to gout, systemic illnesses, or infections in other joints. Some patients may also have suppressed immune systems, preventing their bodies from producing noticeable changes in these lab results.
Your doctor might also test your blood for bacterial infection, as it’s estimated that about two-thirds of patients with sternoclavicular joint (the joint that connects your sternum, or breastbone, to your clavicle, or collarbone) infections are also systemically septic, meaning they have a severe body-wide infection.
Imaging studies you may undergo won’t specifically diagnose the infection, but they can help rule out other possible causes of your pain. An MRI, for example, can be beneficial for detecting swelling in the joint, nearby abscesses (localized collections of pus due to infection), or early osteomyelitis (infection of the bone). X-rays can also be useful, especially when osteomyelitis is suspected. Specifically, a CT scan could show early changes in the bone and the presence of any abscesses around the joint or behind the sternum.
Although all these tests are helpful, the most reliable way to diagnose septic arthritis (a painful infection in a joint) in the sternoclavicular joint is through arthrocentesis. This process involves drawing out fluid from the joint to check for high cell counts, a high percentage of a certain type of white cell called neutrophils, and the presence of bacteria. If there are more than 50,000 cells and more than 90% are neutrophils, and no crystals are found in the fluid, it could indicate an infection. A positive result for bacteria confirms the infection.
While blood cultures are often taken during these evaluations, they cannot fully confirm the infection. As a matter of fact, only about 53% of patients with sternoclavicular joint arthritis are found to have bacteria in their blood. Despite this relatively low detection rate, the test is still considered valuable in aiding the diagnosis.
Treatment Options for Sternoclavicular Joint Infection
Sternoclavicular joint infections can be quite serious and generally require more than just medication. In some cases, treatment may involve a procedure where a needle is used to drain the infection site. However, the most effective treatment usually involves a surgical procedure. In this procedure, the infected area is thoroughly cleaned out (irrigation) and any unhealthy tissue is eliminated (debridement).
This may be followed by a course of tailored intravenous antibiotics. During surgery, doctors exercise caution to evaluate the surrounding areas for trapped abscesses that might keep the infection going. In complex cases where the infection is caused by aggressive organisms or persistent, removal of part of the collar bone (the medial clavicle) might be necessary. When doing this, it’s important to protect the structures behind the breastbone and surrounding ligaments.
If these ligaments are damaged during the procedure, it can lead to pain and instability. There are examples of patients having good functional results after undergoing resection arthroplasty, a surgical procedure that involves the removal of sternoclavicular joint bits and intramedullary ligament reconstruction. This is usually followed by four to eight weeks of intravenous antibiotics.
In less severe cases or in patients with a strong immune system, less invasive management may be an option. In some instances, treatment with antibiotics alone has shown successful results. However, larger and long-term studies are needed to confirm the effectiveness of this approach. Some studies suggest a treatment called needle lavage but there has been limited evidence to confirm its reliability.
If a significant amount of tissue needs to be removed during the procedure, additional coverage in the form of a skin graft, or flap, might be required. Although this is not common, techniques such as using a portion of the pectoral muscle to cover the area have shown excellent outcomes.
Usually, a team of physicians including an infectious disease specialist is involved in treating sternoclavicular joint infections to ensure the best patient outcome. After the operation, or if they opt for non-surgical management, patients can expect to take antibiotics for at least two weeks, depending on the type of infection and the recommendation of the infectious disease specialist.
What else can Sternoclavicular Joint Infection be?
If someone has an infection in the sternoclavicular joint (where the collarbone meets the breastbone), doctors need to consider other conditions that can cause similar symptoms. These conditions might include:
- Arthritis in the sternoclavicular joint
- An infection in the bone of the collarbone (clavicular osteomyelitis)
- A break in the collarbone (clavicular fracture)
- A break in the breastbone (sternal fracture)
- Inflammation in the lining of the lungs (pleuritis)
- Gout
- Dislocation of the sternoclavicular joint
- Condensing osteitis of the clavicle (a rare condition causing bone to thicken)
- Mediastinitis (inflammation of the tissues in the chest)
- A break in the rib (rib fracture)
What to expect with Sternoclavicular Joint Infection
If sternoclavicular joint infections (infections in the joint between the collarbone and breastbone) are spotted and treated quickly, the patient’s chances of recovery are excellent. There have been cases where infections were treated with the removal of the joint leading to no loss of function in the affected upper arm. However, if the infection is left untreated, it can potentially spread to the chest area and become life-threatening if it affects structures behind the breastbone.
After surgery, the initial focus is on getting rid of the infection and ensuring proper healing of the soft tissues. Once the source of the infection is under control, the next step is to improve the functioning of the limb. In cases where sternoclavicular joint is unstable, physical therapy has shown to be helpful. So, if a patient’s recovery is slow post-surgery, additional treatments like physical therapy can be given to boost the rehabilitation process and improve the overall outcome.
Possible Complications When Diagnosed with Sternoclavicular Joint Infection
Complications that could arise after surgery include a required additional surgery, bone infection (osteomyelitis), loss of skin on the affected area that may need flap coverage, instability of the joint, the need for joint reconstruction, difficulty clearing the infection, and potential spread to the chest wall or mediastinal part (the space in the chest between the lungs and the heart). Also, patients could face chronic pain when moving their shoulder or when lifting heavy objects, especially in the event of persistent infections or if a diagnosis is delayed.
- Requirement of another surgery
- Bone infection
- Skin loss over the affected area
- Joint instability
- Need for joint reconstruction
- Inability to fully clear the infection
- Possible spread of the infection to the chest wall or mediastinal area
- Chronic pain associated with shoulder movement or heavy lifting
Preventing Sternoclavicular Joint Infection
If you make changes to certain risk factors that you can control, and understand the risks associated with injecting drugs directly into your veins, it’s possible to lower the chances of catching an infection in the joint where your sternum (breastbone) meets your clavicle (collarbone).