Septic arthritis of the temporomandibular joint assessed by US and CT

A 59-year-old female patient presented to the emergency department with complaints of pain and swelling in the right pre-auricular region for one day. The pain seemed to be aggravated by chewing. Clinical examination revealed a right pre-auricular tumefaction without fluctuation. Laboratory tests showed increased C-reactive protein.

The patient underwent an ultrasound examination of the salivary glands, which showed an unremarkable appearance of the parotid glands. However, an increased amount of fluid within the synovial compartment of the temporomandibular joint (TMJ) was noticed. Floating echogenic foci were found in the fluid, but the synovial vascularity was not increased.

Maxillofacial computed tomography confirmed the existence of marked TMJ effusion with synovial enhancement and multiple enhancing septations. There was no evidence of bone erosion or destruction.

Empiric intravenous antibiotic therapy had already been initiated after the collection of blood samples for culture. In light of the described imaging findings, surgical drainage was performed under the assumption that the patient had temporomandibular joint septic arthritis. Purulent drainage fluid was collected during the procedure and submitted to the laboratory for culture, but it was negative. However, methicillin-susceptible Staphylococcus aureus was detected in blood cultures and clinical improvement followed the switch to culture-directed antibiotic therapy.

Septic arthritis of the TMJ is an infection affecting the temporomandibular joint space. [1] It is a rare condition with a reported incidence of 2 to 10 cases per 100,000 people. [2] Male patients are affected more often. [1] The high vascularity of the TMJ's synovial membrane makes this joint more vulnerable to hematogenous spread of pathogens. [2] Other mechanisms include contiguous dissemination of micro-organisms (eg. in odontogenic or upper respiratory infections) or direct inoculation in the postoperative or trauma setting. [3] Commonly isolated pathogens include Staphylococcus species (predominantly Staphylococcus aureus), Neisseria species, Hemophilus influenzae, Streptococcus species, Pseudomonas aeruginosa, Escherichia coli and Aspergillus flavu. Systemic and autoimmune conditions, such as rheumatoid arthritis, diabetes, immunosuppression, and hypogammaglobulinemia are risk factors. [1]

Patients may present with pain, pre-auricular swelling, trismus, malocclusion, lymphadenopathy, fever, and malaise. A delay in diagnosis may occur due to subtle local and systemic symptoms. [4]

Neutrophilia and an increased C-reactive protein concentration can be found in patients with this condition. [5] Nevertheless, laboratory tests lack specificity and are inconclusive without additional diagnostic investigations. [3] Imaging studies can be helpful to support the diagnosis. Increased intracapsular fluid results in joint space widening, which can be detected in plain films. Ultrasound enables early detection of fluid effusions and assessment of synovial vascularity by color Doppler imaging, which can be increased in this setting. [6] Contrast-enhanced CT is also useful for the detection of joint effusions. [7] Other relevant findings that can be depicted on CT are condylar surface changes, however, these are delayed findings that only become evident after 7-10 days and that may be nonspecific in cases of preexisting degenerative joint disease. Ankylosis can also be seen as an even later manifestation. MRI of the TMJ is regarded as the imaging gold standard due to its excellent anatomic depiction of the joint. [8] MRI findings are identical to those of septic arthritis in other joints and include joint effusion, synovial enhancement, and edema of the bone marrow and adjacent soft tissue [9].

Due to the rarity of this condition, there are no evidence-based recommendations for how it should be managed. Treatment includes broad-spectrum empiric antibiotics followed by culture-directed antibiotic therapy. However, cultures are frequently negative, particularly in cases in which joint aspiration is performed after the initiation of empiric antibiotic therapy. Interventional procedures may be needed, such as arthroscopic surgery, incision and drainage, or surgical resection of the affected area. [3] A complete recovery is possible with appropriate management. [2]

Possible complications may include the local spread of infection, recurrence, destruction of joint articular surfaces, bony ankyloses or fibrotic alterations of the TMJ, acute malocclusion symptoms, limited mouth opening, swelling, and tenderness. [7] Prompt diagnosis and treatment are essential because this condition might be life-threatening or severely incapacitating. [3]

Written informed patient consent for publication has been obtained.