Septic Sternoclavicular Joint: A Case Report

Case Description 

A previously healthy 23-year-old male construction worker who occasionally lifts weights awoke one morning with left anterior chest pain. There was no history of trauma. He played recreational basketball the night before, and felt very mild symptoms in the left sternoclavicular region. Three days before the onset of his symptoms, he lifted weights, including bench press. He felt no symptoms during or after his weight training. The morning of his onset of symptoms, the patient presented to the emergency department due to the severity of his pain. He was tender at his left upper-medial chest. Vital signs were normal. A chest radiograph was negative, and he was prescribed ibuprofen and hydrocodone-acetaminophen for possible costochondritis. Three days later the patient returned to the emergency department, complaining of severe, unimproved pain. Examination continued to show tenderness at the left upper-medial chest. He now had mild redness, warmth, and fullness at the area of his pain and tenderness. He also had reduced shoulder range of motion (ROM). Vital signs continued to be normal. No further diagnostics tests were performed at this time, and he was given a nonsteroidal anti-inflammatory drug (NSAID) for pain.

The patient visited his primary care physician (PCP) later the same day. Blood work and magnetic resonance imaging (MRI) with contrast were ordered. The patient was prescribed prednisone 60mg daily for 7 days for possible costochondritis, and hydrocodone-acetaminophen was also given for pain. He was told to stop taking any previously prescribed NSAIDs. Blood work showed a white blood cell count of 15.2×109 cells/L, erythrocyte sedimentation rate (ESR) of 44mm, and C-reactive protein (CRP) level of 10.4mg/dL. MRI showed extensive edema in the left anterior upper-chest wall most extensively involving the medial pectoralis major muscle with extension to the adjacent soft tissues and a small amount of fluid within the left sternoclavicular joint. MRI findings were thought to be consistent with a partial tear of the superior sternal head of the left pectoralis major muscle, with a sympathetic effusion in the left sternoclavicular joint as a result of the muscle tear. The patient's PCP referred the patient to our sports medicine clinic for management of this pectoralis major tear.

The patient presented to our sports medicine clinic 5 days after the onset of his symptoms. On a scale of 10, he complained his pain was 8 to 10, with no significant change in symptoms since being started on the prednisone 2 days earlier. The hydrocodone-acetaminophen provided minimal relief. He reported chills, but had not recently checked his temperature. He denied intravenous (IV) drug use, history of infection, or skin breakdown anywhere in his body. He was involved in a monogamous sexual relationship. He denied family history of rheumatologic or other autoimmune diseases. On examination, he had normal body weight and normal muscle bulk. He was toxic appearing, unable to walk without significant pain, necessitating the use of a wheelchair for mobility. His skin was warm and sweaty, but his temperature was 37°C and pulse 80 beats per minute. He had redness, warmth, swelling, and tenderness anterior, inferior, and lateral to his sternoclavicular joint. Shoulder ROM was severely limited in all planes due to pain at his left anteromedial chest. There was no increased pain with resisted shoulder adduction. Distal neurovascular examination was intact. Because a septic joint was suspected, he was referred to orthopedics for further evaluation and management, including aspiration of the sternoclavicular joint. One and a half milliliters of bloody fluid was obtained and sent for culture analysis. Blood cultures were obtained and the patient was admitted to the hospital.

In the hospital, the patient was started on IV vancomycin. The prednisone and hydrocodone-acetaminophen were discontinued, and shortly afterward he became febrile up to 39.5°C. On re-review of the MRI, subtle evidence of osteomyelitis and small abscess formation compatible with the patient's joint infection was now appreciated (Fig 1, Fig 2). Aspirate and blood cultures grew methicillin-sensitive Staphylococcus aureus (MSSA). After 3 days of IV antibiotic therapy in the hospital, the patient's symptoms were mildly improved, he was still febrile, and CRP was increased at 21.5mg/dL. The patient was taken for thoracic surgery, and his lateral manubrium, proximal clavicle, and entire sternoclavicular joint were resected. A purulent soft-tissue tract originating from the sternoclavicular joint was encountered. Intraoperative cultures grew out MSSA. Pathology of the resected bone was consistent with acute osteomyelitis. The patient returned to operating room on hospital day 6 for further wound débridement. On hospital day 8, the patient's wound was again débrided, and then closed with a pectoralis major flap with the assistance of the plastic surgery service. A peripherally inserted central catheter line was placed, and on hospital day 13 the patient was dismissed to home with a plan for 4 weeks of home IV nafcillin therapy and close outpatient monitoring. On dismissal, the patient was ambulating without need for an assistive gait device. He needed minimal assistance for bathing, dressing, grooming, and hygiene. Active ROM of the left arm was permitted although the arm was not to be raised above the head until after follow-up evaluation. No predisposing factor was found for the infection. Transesophageal echocardiogram was negative for endocarditis.

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Fig 1. Fat-saturated T2-weighted coronal image through the sternoclavicular joints shows a small amount of fluid in the left sternoclavicular joint (arrow) with mild bone marrow edema in the adjacent manubrium (arrowhead). The distal clavicle is normal, without bone marrow edema. Diffuse edema is present in the surrounding soft tissues, most marked in the pectoralis major.

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Fig 2. Fat-saturated T2-weighted axial image through the clavicular heads shows mild soft tissue thickening and edema about the left clavicular head, extending along the anterior chest wall. A small fluid collection or abscess is shown anterior to the clavicular head (arrow).

Discussion 

This case highlights an unusual case of septic arthritis. Septic joints usually present in older patients with known risk factors for immunosuppression.2 This patient was young and otherwise healthy, denying any predisposing factors for infection. Physical examination was initially benign. Vital signs were normal. Subsequent laboratory investigations revealed signs of infection, with elevated white blood cell counts, ESR, and CRP. He was taking acetaminophen and either NSAIDs or prednisone, which could have masked fever. The patient also gave a history of fairly consistent weight training, but reported no symptoms during or immediately after lifting weights. The patient's symptoms started 3 days after his last session of weight lifting, which would not be consistent with a traumatic muscle tear.

The MRI findings were unusual for septic arthritis and osteomyelitis in that the majority of the abnormal signal was in the extra-articular soft tissues and eccentrically located anteriorly. The joint findings were limited to a very small effusion and subtle enhancing bone marrow edema involving only the manubrial side of the joint. The typical findings of septic arthritis and osteomyelitis include abnormal signal in the bones on both sides of the joint and at least moderate effusion. In this case, the patient had been taking steroids, which likely altered the MRI findings. Medications taken and the clinical findings need to be considered when interpreting imaging findings to suggest a diagnosis.

This case is also unusual in that no predisposing factor for the infection was found. A 2004 review of all septic sternoclavicular joint cases reported in the medical literature found that the most common known predisposing factor was IV drug abuse.1 In this study, cases of IV drug abusers were younger (average age, 35y) and more likely to be male (91%) than the cases who were not IV drug abusers (48y, 69% male). Although no drug testing was performed, the patient denied drug use and examination of the patient's body did not reveal any scars or wounds associated with IV needle use. Other common risk factors for septic sternoclavicular joint include distant site of infection, diabetes mellitus, and trauma.1

Accurate needle placement for joint aspiration is important for confirming the diagnosis and identifying the infectious organism. For the sternoclavicular joint, however, joint aspiration can be very difficult, given the small size of the joint and its proximity to vital structures. Ultrasound guidance for needle placement can be useful in these cases. Diagnostic ultrasound can also help determine if joint fluid is present.3, 4

The patient's long-term prognosis is likely good, despite resection of the sternoclavicular joint and proximal clavicle.5 The sternoclavicular joint acts mainly as a strut, holding the upper limb away from the trunk to allow freedom of movement.6 If the strong costoclavicular ligaments are preserved, the remaining distal clavicle will maintain position and continue to function well.7 The thoracic surgeons at our institution advocate use of a pectoralis major muscle flap to close the wound and minimize infection while still preserving pectoralis major function.5 Rehabilitation will entail gradual return to full active ROM, then introduction of strengthening exercises, especially for the scapular stabilizers. In our clinical experience, most patients recover well within 3 to 6 months with appropriate therapies.

Septic sternoclavicular arthritis is rare, accounting for only 1% of all septic joints. The most common causative agent is Staphylococcus aureus. Resection of the joint is indicated for cases complicated by abscess, bone destruction, or mediastinitis.1, 5 For unclear reasons, axial, mostly cartilaginous joints like the pubic symphysis, sacroiliac joint, and sternoclavicular joint are susceptible to infection in younger patients. In older patients, larger synovial joints are more likely to be infected, including the knee, hip, shoulder, wrist, and ankle.2 In cases where the diagnosis is unclear, but septic joint is suspected, it is reasonable to treat empirically after obtaining appropriate cultures, given the risk of further morbidity with delayed therapy.

Conclusions 

Septic arthritis is an uncommon but potentially disabling and life-threatening medical condition. Although infection is infrequently encountered in physical medicine and rehabilitation or sports medicine clinics, it should be considered in the differential diagnosis for any case with unusual symptoms or an unclear clinical picture localizing to the sternoclavicular joint region.