Bursitis 

Bursae are saclike structures between skin and bone or between tendons, ligaments, and bone. They are lined by synovial tissue, which produces fluid that lubricates and reduces friction between these structures. Bursitis occurs when the synovial lining becomes thickened and produces excessive fluid, leading to localized swelling and pain.^{[1, 2, 3]} See the images below.

Recent studies

In a study of 25 cases of postarthroplasty trochanteric bursitis requiring corticosteroid injection, Farmer et al found that corticosteroid injections were effective treatment and that nonoperative management may be more likely to fail in young patients and patients with leg-length discrepancies. Of the 25 hips, 11 required multiple corticosteroid injections, and symptoms resolved in 20 but not in 5 cases.^[4]

Pretell et al described distal "Z" lengthening of the fascia lata in 13 hips and reported that 12 of the 13 patients reported good results. According to the authors, this technique is less aggressive and can be performed under local anesthesia with little morbidity and disability. Mean surgical time for the procedure was 15 minutes, and 1 seroma was reported as a complication.^[5]

According to Martinez-Taboada et al, in patients with severe septic bursitis, but without extensive cellulitis, aspiration plus I.V. cloxacillin may be sufficient treatment, and in patients with more severe cases of septic bursitis, aspiration along with cloxacillin plus gentamicin may be appropriate in the majority. The investigators studied 82 patients with severe septic bursitis, and the most frequent bacterium isolated was Staphylococcus aureus.^[6]

Bursitis is defined as inflammation of a bursa. A bursa is a lubricating sac of synovial fluid that minimizes friction between moving parts of an extremity. Most people have approximately 160 bursae in the body.

In bursitis, a bursa, which is not normally palpable, becomes swollen, tender, and painful. Pain is aggravated by movement of the specific joint, tendon, or both.

There are three stages of bursitis: acute, recurrent, and chronic.^[7] During the acute phase of bursitis, local inflammation occurs and the synovial fluid is thickened, which results in painful movement. Chronic bursitis leads to continual pain and can cause weakening of overlying ligaments and tendons and, ultimately, rupture of the tendons. Because of the possible adverse effects of chronic bursitis on overlying structures, bursitis and tendinitis may occur together; the differential diagnosis should include both of these diagnoses.

Frequency

Bursitis accounts for 0.4% of all visits to primary care clinics. The incidence of bursitis is higher in athletes, with an incidence of up to 10% in runners.

The most common locations of bursitis are the subdeltoid, olecranon, ischial, trochanteric, and prepatellar bursae. Approximately 85% of cases of septic superficial bursitis occur in men.

Bursitis has many causes, such as autoimmune disorders, crystal deposition (gout or pseudogout), infectious diseases, traumatic events, and hemorrhagic disorders, as well as being secondary to overuse. Repetitive injury within the bursa results in local vasodilatation and increased vascular permeability, which stimulate the inflammatory cascade.

Systemic diseases such as rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, scleroderma, systemic lupus erythematosus, pancreatitis, Whipple disease, oxalosis, uremia, hypertrophic pulmonary osteoarthropathy, and idiopathic hypereosinophilic syndrome have also been associated with bursitis.

In addition, bursitis and other soft-tissue disorders have been associated with generalized hypermobility. Some rheumatic conditions, such as gout, can predispose patients to bursitis.

Infectious bursitis is most common in superficial bursae. Staphylococcus aureus is the most common causative organism and is present in 80% of cases of septic bursitis. However, many other organisms have been implicated in septic bursitis, including bacterial, mycobacterial, and fungal microbes. Factors predisposing individuals to infection include diabetes mellitus, steroid therapy, uremia, alcoholism, and trauma. Septic bursitis most commonly occurs secondary to traumatic injury or cellulitis in overlying skin.

Varying degrees of local inflammation occur in bursitis. The synovial cells increase in thickness and may undergo villous hyperplasia. Granulation tissue and fibrous tissue may form. The bursa becomes filled with fluid, which is often rich in fibrin, and the fluid can become hemorrhagic.^[8]

Patients with bursitis have a history of pain with motion and at rest; swelling; and, often, decreased range of motion of the affected joint.

On physical examination, patients have tenderness at the site of the inflamed bursa. If the bursa is superficial, physical examination findings are significant for localized tenderness, warmth, edema, and erythema of the skin. Joint motion is preserved in septic bursitis; other types of bursitis are associated with limited range of motion. Reduced active range of motion with preserved passive range of motion is suggestive of bursitis, but the differential diagnosis includes tendinitis and muscle injury. A decrease in both active and passive range of motion is more suggestive of other musculoskeletal disorders.

Patients with septic bursitis may have fever, bursal warmth, tenderness that is more severe than in nonseptic bursitis, and associated cellulitis.

In patients with chronic bursitis, the affected limb may show disuse atrophy and weakness. Tendons may also be weakened and tender.

Surgery is not required in most cases of bursitis. Surgical procedures that can be used to treat chronic bursitis, which is refractory to more conservative treatment, are aspiration, incision and drainage, excision of chronically inflamed bursae, and removal of underlying bony prominences.

There are 2 types of bursae: constant and adventitial. Both types can be involved in acute or chronic bursitis.

• Constant bursae

  • Form during embryologic development
  • Lined with endothelial cells
  • Located between tendon and bone or skin
  • Contain synovial cells that secrete a lubricating fluid rich in collagen and proteoglycans
• Adventitial bursae

  • Form later in life in response to repeated trauma or constant friction and pressure
  • Lack endothelial cells
  • Do not contain synovial fluid
  • Examples include those that develop over a bunion and osteochondroma

Upper-extremity bursae

There are approximately 160 bursae in the human body, all of which can become injured. Three upper-extremity bursae most commonly affected are the subacromial, subscapular, and olecranon bursae.^[9]

• Subacromial bursitis: The subacromial bursa is a synovial-lined sac that separates the superior surface of the supraspinatus tendon from the overlying coracoacromial arch and the deltoid muscle. This bursa facilitates movement of the supraspinatus tendon and becomes inflamed secondary to repetitive overuse injury of the supraspinatus tendon. Subacromial bursitis is often coexistent with supraspinatus tendinitis and partial- or complete-thickness tears of the supraspinatus tendon.^[10]
• Subscapular bursitis: Subscapular bursae are found between the anterior surface of the scapula and the posterior chest wall. The 2 commonly affected bursae are located superomedially between the serratus anterior muscle and the chest wall. These bursae become inflamed as a result of abnormal bony structures or soft-tissue changes that affect the movement of the scapula over the posterior chest wall.
• Olecranon bursitis: There are 2 olecranon bursae that can become inflamed: one lies between the tendon of the triceps muscle and the posterior ligament of the elbow and the olecranon; the other is more superficial, lying between the attachment of the triceps to the olecranon and the skin. The more superficial bursa is predisposed to direct trauma or cumulative microtrauma from activities requiring frequent elbow motion (eg, swimming, skiing, gymnastics, weight lifting). This type of bursitis is often recurrent.^{[11, 12, 13]}

Lower-extremity bursae

Several lower-extremity bursae can also be affected; the most common ones are in the hip, the knee, and the ankle.^{[14, 15, 16]}

• Ischiogluteal bursitis: The ischiogluteal bursa lies deep to the gluteus maximus over the ischial tuberosity. Inflammation of this bursa is associated with sedentary occupations and is caused by direct stress on the bursa, giving it the nickname weaver's bottom. Patients have pain with sitting and walking and have localized tenderness over the ischial tuberosity. Physical examination is often significant for pain with passive hip flexion and resisted hip extension.
• Greater trochanter bursitis: There are up to 3 bursae associated with the greater trochanter. Bursitis of the greater trochanter is common in overweight, middle-aged women, and it is associated with acute trauma, overuse, and mechanical factors. The clinical presentation is of deep, aching lateral hip pain that may radiate into the buttocks or lateral knee. Pain is worse with activity and stretching and may be worse at night. Patients have severe tenderness to palpation over the greater trochanter. On physical examination, pain also occurs with resisted hip abduction and external rotation.^{[17, 18, 19, 20]}
• Bursitis of the knee: The knee has 11 associated bursae, of which 4 are commonly involved: medial collateral ligament bursa, the pes anserine, prepatellar, and Baker's cyst (popliteal bursitis).^[15]

  • Medial collateral ligament bursitis: The medial collateral ligament bursa is most commonly injured secondary to a twisting injury with external tibial rotation. Medial joint line pain occurs and may limit knee extension. This may be confused with a meniscal tear on physical examination.
  • Pes anserine bursitis: Pes anserine bursitis occurs behind the medial hamstring, under the insertion site of the sartorius, gracilis, and semitendinous muscles on the medial flare of the tibia just below the tibial plateau. This condition is not usually associated with overuse but may occur in patients with medial compartmental osteoarthritis. Clinically, patients complain of pain and tenderness over the anteromedial knee that is worse with knee flexion. This condition may be confused with medial meniscal pathology.^{[21, 22]}
  • Prepatellar bursitis: Prepatellar bursitis, also known as housemaid's knee, occurs anteriorly over the patella. It is associated with trauma or with chronic, repetitive kneeling. This bursa is also a common site for septic bursitis, and this diagnosis should be considered when there is skin injury, erythema, warmth, or severe tenderness over the patella. In patients with septic prepatellar bursitis, the patella is not palpable and knee flexion is painful.
  • Baker's cyst (popliteal bursitis): Popliteal bursae, or Baker's cysts, occur in the posterior joint capsule of the knee, with associated local swelling and pain with walking, jumping, and squatting. MRI or ultrasound can differentiate an isolated bursitis from intra-articular injury (also see the eMedicine Radiology article Baker Cyst).
• Retrocalcaneal bursitis: The most commonly inflamed bursa in the ankle is the retrocalcaneal bursa, which is anterior to the Achilles tendon and posterior to the calcaneus. Bursitis in this region is commonly caused by local trauma associated with poorly designed shoes. Patients complain of posterolateral heel pain and may have a posterior heel prominence, often called a "pump bump," as well as local swelling and tenderness over the Achilles tendon. Pain is increased by squeezing the bursa from side to side and anterior to the Achilles. A heel lift and open-back shoes help alleviate pressure.^[23]