Orthopaedic Surgery - Prepatellar Bursitis

Basics

Prepatellar bursitis is inflammation or distention of the:

Prepatellar bursa

located directly anterior to the patella.

Bursae are small, fluid-containing sacs positioned between tissues that move against one another. Their purpose is to:

Reduce friction

and facilitate smooth movement.

The bursal lining consists of synovial tissue that both:

Produces

and

Resorbs fluid.

Classification

Prepatellar bursitis may be classified as:

Traumatic

Septic

Inflammatory

Traumatic Bursitis

Traumatic bursitis may result from:

A direct blow

or

Repeated low-grade pressure and microtrauma.

Septic Bursitis

Septic bursitis results from:

Infection of the prepatellar bursa.

This may follow:

Skin abrasion

Puncture wound

Direct inoculation

or occasionally spread from surrounding tissue.

Inflammatory Bursitis

The bursa may become inflamed in association with systemic or crystal-related disease such as:

Gout

Rheumatoid arthritis

and, much less commonly,

Tuberculosis

or other chronic inflammatory/infectious disorders.

Synonyms

Common historical names include:

Housemaid’s knee

Carpenter’s knee

Carpet-layer’s knee

These terms reflect the association with repeated:

Kneeling.

Epidemiology

Prepatellar bursitis is:

Common.

It is especially frequent in:

Middle-aged and older adults

and in individuals whose work or activities require prolonged kneeling.

Both sexes may be affected.

Risk Factors

The principal risk factor is:

Repeated pressure or trauma over the anterior knee.

High-risk activities include occupations involving:

Frequent kneeling

Crawling

Direct pressure on the kneecap

Examples include:

Flooring work

Carpentry

Carpet laying

Household cleaning

Genetics

There is no known Mendelian inheritance pattern.

Etiology

Common causes include:

Acute direct trauma

and

Repetitive minor trauma.

Acute Trauma

A direct injury such as:

A fall onto the knee

or

Motor vehicle trauma

may produce hemorrhage and inflammation within the bursa.

Repetitive Microtrauma

Repeated kneeling may irritate the synovial lining and lead to:

Chronic fluid accumulation

Synovial thickening

and sometimes

Fibrosis.

Diagnosis

Diagnosis is primarily based on:

History

Physical examination

and, when infection is suspected,

Bursal aspiration.

Signs and Symptoms

Typical findings include:

Anterior knee swelling

Pain

Tenderness

and sometimes

Erythema.

Pain

Pain is often worsened by:

Kneeling

Direct pressure over the patella

and

Knee movement when the enlarged bursa is compressed.

Swelling

The characteristic finding is a:

Visible, localized swelling directly over the patella.

The swelling is typically:

Extra-articular

rather than representing a true knee-joint effusion.

Erythema and Warmth

Redness and increased warmth may occur in both inflammatory and septic bursitis.

Marked:

Erythema

Tenderness

Warmth

or systemic symptoms should increase concern for:

Infection.

Physical Examination

The affected knee should be compared with the:

Contralateral side.

Bursa Examination

Assess:

Size of swelling

Tenderness

Fluctuance

Skin integrity

Warmth

Erythema

Joint Effusion

Determine whether there is an associated:

Intra-articular effusion.

In isolated prepatellar bursitis, the swelling remains primarily:

Anterior to the patella.

Extensor Mechanism

Palpate the:

Quadriceps tendon

Patella

Patellar tendon

and confirm active:

Knee extension.

This helps exclude associated:

Patellar fracture

Quadriceps tendon rupture

Patellar tendon rupture.

Patellar Tenderness

Direct bony tenderness over the patella should raise concern for:

Fracture

or another osseous abnormality.

Range of Motion

Knee motion may be mildly limited because of:

Pain or mechanical pressure from the enlarged bursa.

Marked pain with passive range of motion is less typical and should raise concern for:

Septic arthritis or another intra-articular process.

Laboratory Tests

Routine laboratory studies are not required in every uncomplicated traumatic case.

If infection is suspected, useful tests may include:

Complete blood count

ESR

CRP

Bursal Aspiration

When septic bursitis is suspected, aspirated fluid should be sent for:

Cell count with differential

Gram stain

Culture and sensitivity

Crystal analysis

Crystal Analysis

Crystal examination may identify:

Monosodium urate crystals

or

Calcium pyrophosphate crystals

suggesting:

Gout

or

CPPD.

Imaging

Plain Radiographs

AP and lateral knee radiographs may be obtained when there is concern for:

Fracture

Foreign body

Calcification

Underlying bony abnormality

or another intra-articular disorder.

Radiographs are often normal in isolated bursitis.

Ultrasound

Ultrasound may help demonstrate:

Fluid within the prepatellar bursa

and can assist with:

Needle aspiration

when the anatomy is difficult or the collection is small.

Pathological Findings

In septic prepatellar bursitis, the most common causative organism is:

Staphylococcus aureus.

Other gram-positive organisms, particularly:

Streptococcal species

may also be responsible.

Differential Diagnosis

Important alternatives include:

Septic arthritis

Cellulitis

Patellar fracture

Intra-articular effusion

Inflammatory arthritis

Crystal arthropathy

Traumatic hematoma

Septic Arthritis

Septic arthritis usually produces:

Severe pain with passive joint motion

Marked restriction of motion

and often a:

True intra-articular effusion.

This distinction is clinically important because septic arthritis requires urgent treatment.

Cellulitis

Cellulitis may produce:

Diffuse erythema

Warmth

Tenderness

without a clearly defined fluctuant bursal collection.

Treatment

General Principles

Treatment depends on whether the bursitis is:

Traumatic

Inflammatory

or

Septic.

Traumatic or Aseptic Bursitis

Initial management generally includes:

Activity modification

Avoidance of kneeling

Compression

Ice or heat for comfort

NSAIDs when appropriate

Immobilization

A knee immobilizer may be used temporarily when pain is substantial.

Prolonged immobilization should generally be avoided because it can lead to:

Knee stiffness

and

Quadriceps weakness.

Spontaneous Resolution

Many traumatic cases improve with:

Conservative treatment alone.

Aspiration in Aseptic Bursitis

Aspiration may be considered for a very large or symptomatic bursa, but repeated aspiration should be avoided when possible because it increases the risk of:

Infection

and

Chronic drainage.

Septic Bursitis

When infection is suspected:

Aspirate the bursa before antibiotics when clinically feasible

and obtain appropriate cultures.

Antibiotic Therapy

Empiric treatment should cover common gram-positive organisms, particularly:

Staphylococcus aureus

while awaiting culture results.

The antibiotic route and setting depend on:

Severity

Systemic illness

Comorbidities

Local infection extent.

Not every septic bursitis case requires parenteral therapy; clinically stable patients may sometimes be managed with appropriate oral antibiotics and close follow-up.

Hospital Admission

Hospitalization and intravenous antibiotics are appropriate when there is:

Systemic toxicity

Rapidly progressive infection

Ascending lymphangitis

Immunocompromise

or inability to manage safely as an outpatient.

Incision and Drainage

Operative drainage may be required when there is:

Persistent purulent collection

Failure to improve with aspiration and antibiotics

Loculated infection

or

Chronic draining infection.

Physical Therapy

Formal therapy is not routinely required in uncomplicated cases.

It may be useful after prolonged symptoms or immobilization to restore:

Knee range of motion

Quadriceps strength

Normal gait.

Medication

NSAIDs

NSAIDs may be used for:

Pain

and

Inflammation

in traumatic or noninfectious bursitis.

Analgesics

Acetaminophen or other analgesics may be used when NSAIDs are inappropriate.

Antibiotics

Antibiotics are indicated for:

Septic bursitis.

Definitive therapy should be adjusted according to:

Culture and susceptibility results.

Surgery

Surgical excision or bursectomy is uncommon.

It may be considered for:

Chronic recurrent bursitis

Persistent fibrotic or thickened bursa

Painful nodular synovial thickening

Refractory septic bursitis

Chronic Bursectomy

Patients with longstanding occupational bursitis may occasionally develop:

Fibrosis

Thickened synovium

or

Painful nodules

that fail to respond to conservative treatment.

These may require:

Surgical bursectomy.

Follow-Up

Follow-up should be individualized according to:

Cause

Symptoms

and

Response to treatment.

Septic cases require closer reassessment to ensure:

Clinical improvement

Resolution of erythema

Decreasing swelling

No progression of infection.

Referral

Urgent orthopaedic or hospital evaluation is appropriate for:

Suspected septic arthritis

Progressive septic bursitis

Ascending lymphangitis

Systemic illness

Failure of outpatient treatment.

Prognosis

The prognosis is generally:

Good.

Most traumatic or inflammatory cases improve with:

Activity modification

NSAIDs

Protection from pressure

and time.

Septic Prognosis

Septic bursitis usually responds well when treated promptly with:

Appropriate drainage

and

Antibiotic therapy.

Complications

Infection

A previously sterile bursa may become infected, particularly after:

Repeated aspiration

Skin breakdown

or

Direct contamination.

Chronic Drainage

Repeated procedures or persistent infection may lead to:

A draining sinus

or chronic wound problems.

Recurrence

Continued kneeling or failure to modify the provoking activity may result in:

Recurrent bursitis.

Stiffness

Prolonged immobilization can cause:

Loss of knee motion

and

Quadriceps weakness.

Patient Monitoring

Patients should be monitored for:

Swelling

Pain

Erythema

Warmth

Range of motion

and, in infectious cases,

Signs of systemic spread.

Key Principle

Prepatellar bursitis is inflammation or distention of the bursa directly anterior to the patella, most commonly caused by repetitive kneeling, direct trauma, or infection.

The key clinical distinction is between:

Aseptic traumatic/inflammatory bursitis

and

Septic bursitis.

Most aseptic cases respond to:

Pressure avoidance, symptomatic treatment, and short-term activity modification, whereas suspected septic bursitis requires:

Aspiration, culture-directed antibiotic therapy, and drainage when necessary.