Bursitis is a painful inflammatory condition affecting bursae—small fluid-filled sacs that cushion points of friction between muscles, tendons, and bones near joints.

These sacs facilitate smooth movement by reducing friction during motion. When bursae become inflamed or irritated, discomfort, swelling, and restricted movement ensue.

Mechanical Stress and Repetitive Motion

The most common cause of bursitis is mechanical overuse resulting from repetitive movements or sustained pressure on bursae. Occupations and activities involving prolonged kneeling, leaning on elbows, or repetitive arm motions exert persistent stress, especially around commonly affected sites such as shoulders, elbows, hips, and knees.

For instance, carpet layers, gardeners, painters, and athletes involved in overhead throwing often develop bursitis due to the cumulative impact on periarticular bursae. Continuous pressure compresses the bursae between surrounding tissues and bony prominences, leading to inflammation over time.

Traumatic Injuries

Direct trauma to a bursa is another significant trigger for bursitis. Even minor blunt injuries may cause irritation or bleeding within the bursal sac, resulting in swelling and pain. Frequently, patients may not recall this trauma, especially if initially asymptomatic. Acute trauma disrupts the normal cushioning function of the bursa and can exacerbate inflammatory cascades, elevating the risk for both non-infectious and infectious bursitis.

Infectious Causes

Though less prevalent, septic bursitis arises when bacteria invade the bursa, typically via skin punctures or surrounding infections. Staphylococcus aureus is the predominant pathogen implicated. Infection transforms the sac’s fluid into pus, causing severe pain, redness, swelling, and systemic symptoms such as fever. Prompt identification and treatment with antibiotics are critical to prevent complications including abscess formation or systemic spread.

Systemic and Inflammatory Diseases

Bursitis frequently coexists with chronic systemic inflammatory disorders. Conditions such as rheumatoid arthritis, gout, psoriatic arthritis, and systemic lupus erythematosus contribute to bursal inflammation either directly through autoimmune mechanisms or indirectly via crystals deposition (in gout). These diseases alter immune responses, predispose to persistent inflammation, and reduce tissue resilience against mechanical stressors.

Anatomical and Physiological Factors

Aging joints and associated degenerative changes increase susceptibility to bursitis. With advancing age, tendons and muscles lose elasticity and repair capacity, causing greater strain on bursae during movement. Structural anomalies like leg length discrepancy or joint misalignment impose asymmetric loading on bursae, promoting inflammation. Additionally, obesity exaggerates mechanical loading on lower extremity bursae, particularly hips and knees, elevating bursitis risk.

Other Contributing Factors

Repetitive stress from certain hobbies or athletic pursuits, poor posture, and incorrect technique in physical activities can initiate bursitis. Prolonged immobilization or inactivity might also affect bursal health by impairing normal fluid circulation within the sac. Moreover, certain medications and metabolic disorders can influence tissue integrity, indirectly encouraging bursitis development.

Dr. Angela Voight, M.D., an orthopedic sports medicine physician at Summit Orthopedics, is noted for her specialization in treating bursitis among other conditions. She states her goal as follows: “My goal is to help people return to the activities they love as quickly and safely as possible. I want patients to feel as though they are well cared for, that their concerns are heard, and that we work together to find the best treatment plan."

Bursitis is primarily caused by repetitive mechanical stress and traumatic injury to bursa sacs, with additional factors including infections and systemic inflammatory diseases playing critical roles. Aging, anatomical variations, and lifestyle factors further predispose individuals to this condition. Accurate identification of the causative factors, combined with adequate preventive and therapeutic measures, is essential to alleviate symptoms and restore functional mobility.