Septic Bursitis

Other Names

• Septic Bursitis
• Infectious Bursitis
• Complicated Septic Bursitis

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Background

• This page refers to septic/ infectious bursitis, meaning inflammation of the bursa due to an infection

History

• Needs to be updated

Epidemiology

• About 1/3 of cases of olecranon bursitis or prepatellar bursitis are septic
• Septic olecranon and prepatellar bursitis accounts for 0.01% to 0.1% of admissions

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Introduction

Comparing septic and aseptic bursitis

Anatomic illustration of the olecranon bursa

Anterior and medial bursae about the knee.

General

• Most common in olecranon and prepatellar bursa due to superficial nature
• Seen in about 1/3 of cases of prepatellar and olecranon bursa
• Management varies widely due to absence of recommendations
• Most mild to moderate cases can be managed empirically with oral antibiotics and without aspiration
• Can be difficult to distinguish from Aseptic Bursitis

Pathophysiology of Superficial Bursa

• Usually occurs through the skin either due to
  • Direct inoculation during an injury, aspiration, or injection
  • Via spread from a skin infection
• Hematogenous contamination
  • Very rare, superficial bursa have meagre blood supply

Pathophysiology of Deep Bursa

• Far less common than superficial bursa
• Often results in diagnostic delays
• Without an obvious cause, she be ascribed to:
  • Hematogenous spread
  • Contiguous from regional arthritis, osteomyelitis, soft tissue infection

Superficial Bursitis (common)

• Olecranon Bursitis
• Prepatellar Bursitis
• Infrapatellar Bursitis

Deep Bursitis (rare)

• Subacromial Bursitis
• Ischial Bursitis
  • Reported in patients with spinal cord injury
  • Reported in patient who's occupation was weaving
• Trochanteric Bursitis

Associated Conditions

• Septic Arthritis
• Osteomyelitis
• Cellulitis

Microbiology

• Bacterial
  • Staph Aureus responsible for 80% of cases
  • Streptococci is #2
  • Less common: Coagulase-negative staphylococci, enterococci, Escherichia coli, Pseudomonas aeruginosa, and anaerobic bacteria
  • Atypical Mycobacteria has been reported in association with immunosuppression
• Fungal
  • Typically candida species
  • Exceedingly rare
  • Can mimic mechanical condition, run a chronic course

Anatomy of a Bursa

• Closed, extra-articular space that decrease friction between soft tissue and bony protuberances
• Composed of connective tissue with a synovial lining
• Can be either deep or superficial
• The number of bursa is estimated to be over 150, although this is highly variable
• Some bursa communicate with the adjacent joint cavity (e.g. iliopsoas bursa)

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Risk Factors

Demographics

• 80% are male, Age 40-80
  • Constitute population most exposed to trauma, microtrauma from occupational or recreational activities

Systemic

• Diabetes Mellitus
• Alcohol Use Disorder
• Glucocorticoid Therapy
• Rheumatoid Arthritis
• Protease inhibitor therapy to treat hepatitis C

Environmental

• Increases in summer due to increase in outdoor activities

Procedural

• Corticosteroid Injection

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Differential Diagnosis

Differential Diagnosis of Septic Bursitis

• Varies highly based on location/ risk factors
• Consider
  • Aseptic Bursitis
  • Acute Monoarthritis
  • Trauma
  • Gout
  • Pseudogout
  • Septic Arthritis
  • Cellulitis
  • Inflammatory Rheumatic Disease
  • Erysipelas
  • Hemobursa
  • Osteomyelitis

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Clinical Features

Prepatellar septic bursitis. Note the scar denoting previous bursectomy

History

• Pain
• Warmth, redness, swelling, fullness at the site
• Functional impairment of affected bursa/ extremity

Physical Exam

• If superficial, local swelling, warmth and erythema may be present
  • Observe for puncture wound, skin changes, abrasions, contusions
• If deep, physical exam findings are far more variable
• Fever is reported in 20% to 77% of cases
• Passive range of motion should be preserved
  • In Septic Arthritis, severe functional impairment/pain exists due to intra-articular effusion

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Evaluation

Ultrasonography in a patient with prepatellar septic bursitis, longitudinal view: note the anechoic bursal effusion (asterisk) and synovial lining hypertrophy (arrowhead).

Aspiration in a patient with prepatellar septic bursitis, with the needle inserted longitudinally along the axis of the probe; the needle (arrowhead) is visible within the bursal effusion (asterisk).

Computed tomography in a patient with tuberculous trochanteric bursitis, osteitis (asterisk), and a sinus tract (arrowhead).

General

• Clinical features are often insufficient to distinguish from other causes of bursitis
• Bursal effusion, erythema and pain are not sufficiently specific
• One study of 55 publications concluded the cause of bursitis can not be determined based on clinical findings alone

Aspiration

• Advocated if any uncertainty in diagnosis, especially in deeper bursa
• Appropriateness of routine aspiration in patients with mild symptoms is not widely agreed upon
  • In most cases, microbiology data does not affect the choice of antibiotics or clinical course
  • Thus, bursal fluid aspiration, analysis is not routinely necessary

Fluid Analysis

• Gross appearance provides diagnostic orientation
  • Clear yellow or blood tinged: aseptic
  • Cloudy or purulent: septic
• Cell count
  • Higher in septic than aseptic bursitis
  • No universally agreed upon cutoff for distinguishing between them
  • One study: septic bursitis WBC (690 to 418,000/mm3) vs aseptic bursitis WBC (50 to 10,000/mm3)
  • In patients with prepatellar bursitis: WBC cutoff of 2000/mm3 was 94% sensitive and 79% specific
• Culture
  • Culture should be sent even if positive for monosodium urate crystals, as co-infection does occur
  • Strongly consider continuing antibiotic therapy until culture results are available
  • Identifies organism in 67^ to 100% of patients
• Gram Stain
  • Positive results vary widely from 15% to 100%

Serology

• Blood Culture
  • Diagnostic yield is low
  • Bacteremia is uncommon in superficial septic bursitis
  • Across studies, rate of positive blood culture ranges from 4% to 30%

Radiographs

• Radiographs of the affect joint are typically obtained
  • In the absence of trauma or foreign body, they may not be necessary
• Potential findings
  • Soft tissue swelling
  • Subcutaneous fat stranding
  • Enthesophytes
  • Rarely, gas bubbles indicating infection by a gas-producing organism

Ultrasound

• Findings
  • Swelling or bursal effusion
  • Edema, cobblestoning
  • Thickening of the bursal wall
• Bursal effusion in septic bursitis
  • Thick and echogenic
  • Mimics hypertrophy of the bursal synovial lining
  • Compressible, mobilizable
  • Absence of increased blood flow on power doppler
• Aid in differential diagnosis
  • Detect foreign bodies
  • In patients with gout, can see tophus, rheumatoid nodule or calcifications
• Limitations
  • Can not distinguish septic bursitis from other causes of bursitis (crystal, rheumatic, post-traumatic, etc)
• Rare considerations
  • Grain-of-rice appearance of small echogenic structures has been reported in tuberculosis, rheumatoid arthritis
• Procedural
  • Aspiration can be guided with ultrasound
  • May not be necessary for superficial bursa
  • Often necessary for deeper structures

MRI

• Not typically indicated
• Helpful for
  • Look for abscess, evidence of osteitis
  • Can help differentiate septic from aseptic bursitis

CT

• Indications unknown

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Classification

Ho and Su Severity Classification

• Mild
  • Mild-to-moderate local inflammation
  • Usually without skin breaching or systemic signs
  • Treatment: oral antibiotics, outpatient follow up
• Moderate
  • Moderately severe local inflammation
  • With or without minor skin breaching and systemic signs
  • Treatment: oral antibiotics, outpatient follow up
• Severe
  • Extensive infection with marked erysipelas or an infected wound
  • Systemic signs including a fever and rigors
  • Peripheral blood white blood cell count > 10,000/mm3
  • Treatment: admission, IV antibiotics

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Management

Antibiotic Therapy

• General
  • No clear recommendations from any medical societies
• Empiric treatment
  • Coverage against staphylococci, streptococci
  • Initiate after aspiration if appropriate
  • Examples: penicillin or first-generation cephalosporin, amoxicillin/clavulanic acid
• PO vs IV
  • Oral antibiotics are usually appropriate in most patients without systemic symptoms
  • IV antibiotics should be utilized in systemically ill or immunocompromised patients
• Duration
  • Varies widely across publications, no agreed upon duration
  • Typically adjust based on clinical course of 2 to 3 weeks
  • 2 weeks has been proposed for mild or moderate cases
  • In severe cases, IV antibiotics for the first 4-10 days followed by oral antibiotics

Operative

• Indications
  • Not well standardized
  • Consider as second line treatment for refractory or recurrent cases
  • Consider for severe infection, skin complications, foreign bodies, depressed immunity, or unfeasible needle aspiration
• Technique
  • Bursectomy

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Rehab and Return to Play

Rehabilitation

• No clear guidelines, varies depending on location and treatment

Return to Play/ Work

• No clear guidelines, varies depending on location and treatment

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Prognosis and Complications

Prognosis

• Surgical
  • Swiss study using bursectomy for moderate/severe olecranon bursitis had a failure rate of 13%
  • Review study: failure rates of 20% after bursectomy compared to 0-14% after antibiotics only (need citation)
  • Review of 29 studies of olecranon bursitis suggested surgery is less effective, produced more complications

Complications

• Post operative
  • Complication rates are high in surgical than non-surgical patients
• Recurrent infection

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See Also

• Infectious Disease Main
• Bursopathies Main

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