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 — from a fall, blow, or blunt impact — can trigger bursitis. Even seemingly minor injuries may irritate the bursal lining or cause bleeding within the bursal sac, leading to inflammation, swelling, and pain. Because bursae provide cushioning for tendons and bones, disruption to their structure can interfere with their protective function and provoke an inflammatory cascade. In some cases, trauma may even increase susceptibility to infection by compromising skin integrity. While repetitive stress remains a more common precipitant of bursitis, trauma is a recognized—and sometimes overlooked—cause, especially in superficial bursae.

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 often coexists with chronic systemic inflammatory or crystal‑arthropathy disorders. Autoimmune conditions such as rheumatoid arthritis, psoriatic arthritis, systemic lupus erythematosus, and spondyloarthropathies may trigger bursal inflammation through immune‑mediated inflammatory processes.

Meanwhile, in conditions like gout, crystal deposition (e.g. urate crystals) can accumulate in bursae, provoking local inflammation. These systemic diseases alter normal immune responses and tissue resilience — increasing the likelihood that bursal tissue will react with inflammation, especially when combined with mechanical stress or repetitive use.

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.