Written by Braden Womack with Dr. Nabil Ebraheim
Bursas are synovium-lined, sac-like structures located throughout the body between skin and tendon or tendon and bone (1,2). The main function of bursa is to reduce the friction between areas of movement and some common locations are the shoulder, knee, hip, and elbow (1). When these areas become swollen or inflamed it is known as bursitis. During this abnormality the bursa will enlarge with fluid causing any movement against or direct pressure upon the area to produce pain for the patient (2).
There are many causes of bursitis that one should be aware of, five of which are prolonged pressure, trauma, sepsis, autoimmune conditions, and idiopathic origins. Prolonged pressure is when the bursa is stressed between a hard surface and bony prominence. Examples of this prolonged pressure include over-use of the area with repetitive motions, frequently resting one’s elbow on their desk, and working on one’s knees without adequate padding. Traumatic bursitis is caused when direct pressure is applied to the bursa, often unknowingly as it may have seemed benign at the time (2). Traumatic bursitis does put the patient at risk of developing septic bursitis, often difficult to distinguish against aseptic bursitis, which is most induced by invasive procedures (2,3). Staphylococcus aureus causes roughly 80% of septic bursitis through what is believed to be a direct inoculation, instead of a hematogenous route due to the poor blood flow seen to bursas (4). Bursitis can also be caused by autoimmune conditions such as rheumatoid arthritis, osteoarthritis, systemic lupus erythematosus, scleroderma, spondyloarthropathy, and gout. The last common cause of bursitis is idiopathic in origin (2).
Bursitis can be broken up further to acute bursitis and chronic bursitis. Acute bursitis is typically caused by trauma, infection, or crystalline joint disease resulting in pain on palpation of the bursa as well as a decrease in range of motion that is secondary to pain. Whereas chronic bursitis is typically caused by inflammatory arthropathies, repetitive motions, or microtraumas most often causing painless swelling and thickening of the bursa. Examination of the skin is an important distinguishing factor for acute and chronic bursitis as trauma, erythema, and warmth should all be evaluated to make a proper diagnosis (2).
Diagnosis of many types of bursitis can be made clinically without further studies, however in the case of trauma, concern for foreign bodies, or fractures imaging can play an important role in diagnosis. Basic plain film imaging can be used when evaluating a superficial bursa however, for a deeper bursa MRI and ultrasound can be used (1). Ultrasound will also provide the added benefit of showing real-time images to observe changes in active and passive movements (2). When evaluating an inflamed bursa, aspiration is a critical tool to distinguish between septic and aseptic bursitis as the aspirated fluid should be sent for a basic cell count and cell cultures (3).
Treatment for bursitis depends on the type and causative agent as most bursitis will heal on their own without intervention. To combat the patient’s pain, bursitis can be treated with a conservative treatment plan involving rest, ice, compression, and elevation as well as NSAIDS and/or acetaminophen for pain (2). With deeper bursitis corticosteroid injections can provide symptomatic relief however, this course of treatment is not recommended for superficial bursa and can delay the diagnosis of another condition such as a tear. Physical therapy is another important treatment method to strengthen the muscles that support the area around the bursa (2). For septic bursitis the typical course of treatment is oral antibiotics as an outpatient but systemic IV antibiotics may be needed if signs of widespread sepsis are present (4). The last line of treatment is surgery which is most often used only as a last resort when all other conservative treatment methods fail (2).
References
1. Chatra PS. Bursae around the knee joints. Indian J Radiol Imaging. 2012 Jan;22(1):27-30. doi: 10.4103/0971-3026.95400. PMID: 22623812; PMCID: PMC3354353.
2. Williams CH, Jamal Z, Sternard BT. Bursitis. [Updated 2021 Aug 2]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513340/
3. Aaron, Daniel L. MD; Patel, Amar MD; Kayiaros, Stephen MD; Calfee, Ryan MD Four Common Types of Bursitis: Diagnosis and Management, American Academy of Orthopaedic Surgeon: June 2011 - Volume 19 - Issue 6 - p 359-367
4. Cea-Pereiro JC, Garcia-Meijide J, Mera-Varela A, Gomez-Reino JJ. A comparison between septic bursitis caused by Staphylococcus aureus and those caused by other organisms. Clin Rheumatol. 2001;20(1):10-4. doi: 10.1007/s100670170096. PMID: 11254233.
