Bursitis

KEY FACTS

Terminology

• Bursitis: Inflammation of lining of bursa

Imaging

• Majority of bursae are not visible on US unless distended with fluid or proliferative synovial tissue
• Acute bursitis: Thin-walled bursa distended with hypoechoic fluid, peribursal hyperemia
• Chronic bursitis: Thickening of bursal wall, more mature synovial proliferation, more echogenic content, & increased likelihood of intrabursal hyperemia

Can simulate soft tissue mass or abscess

If echogenic foci in distended bursa, consider crystal deposition
• Most bursae are accessible to US examination

Use minimal transducer pressure to avoid effacement of superficial bursae

Amiable to US-guided aspiration ± injection

Top Differential Diagnoses

• Cystic collection from underlying structure, e.g., parameniscal cyst
• Abscess or collection
• Cyst adjacent to bursa, e.g., epidermoid or hematoma

Clinical Issues

• Treatment

Rest; antiinflammatory agents: US-guided corticosteroids ± long-acting, local anesthetic injection

Excision for resistant cases

Diagnostic Checklist

• Small amount of fluid is normal in subacromial-subdeltoid bursa, deep infrapatellar bursa, & retrocalcaneal bursa
• Bursitis is common; infective bursitis is uncommon
• Synovial-type bursa are prone to every synovial-based pathology

TERMINOLOGY

Synonyms

• Bursopathy, student’s elbow (olecranon bursitis), ischial tuberosity (ischiogluteal) bursitis, trochanteric (hip) bursitis, prepatellar bursitis (housemaid’s knee), infrapatellar bursitis (preacher’s knee)

Definitions

• Bursitis: Inflammation of lining of bursa

Bursa: Synovial-lined sac interspersed between tissues at areas of friction

2 types of bursae

– Synovial bursae: Constant synovial-lined bursae, which develop in utero in defined anatomical locations

– Adventitious bursae: Nonsynovial-lined bursae, which are acquired post partum due to friction between opposing tissues

IMAGING

General Features

• Best diagnostic clue

Fluid-distended sac in typical location
• Location

Subacromial-subdeltoid bursa: Large bursa overlying rotator cuff tendons

– Communicates with glenohumeral joint if full-thickness tear of supraspinatus/infraspinatus tendons

Olecranon bursa: Overlies olecranon process & distal end of triceps tendon

Ischial tuberosity bursa: Between ischial tuberosity (hamstring tendon attachment) & gluteus maximus muscle

Iliopsoas bursa: Large bursa between iliopsoas tendon & anterior part of hip joint

– Communicates with hip joint in 15% of subjects

Trochanteric bursa: Laterally overlies gluteus medius & minimus tendon insertion into greater trochanter femur

Subgluteus minimus bursa: Between gluteus minimus tendon & anterior facet greater trochanter

Subgluteus medius bursa: Between gluteus medius tendon & posterosuperior facet greater trochanter

Semimembranous bursa: Posteromedial to semimembranous musculotendinous junction & tendon posteromedial aspect distal thigh

Pes anserine bursa: Between sartorius, gracilis, semitendinosus tendons, & posteromedial tibia

Prepatellar bursa: Overlies inferior pole of patella & proximal patellar tendon

Infrapatellar bursa: Overlies mid-to-distal aspect of patellar tendon

– Do not confuse with deep infrapatellar bursa

Small amount of fluid in deep infrapatellar bursa is normal

Retrocalcaneal bursa: Between calcaneus, Achilles tendon, & Kager fat pad

– Small amount of fluid in retrocalcaneal bursa is normal

Superficial calcaneal bursitis: Overlies distal aspect of Achilles tendon
• Size

Few mm to several cm, depending on degree of bursal distension
• Morphology

Communicating or noncommunicating bursa

– Communicating refers to bursa communicating with adjacent joint, e.g., iliopsoas bursa

Radiographic Findings

• Radiography

Soft tissue swelling

Ultrasonographic Findings

• General

Majority of bursae not visible on US unless distended with fluid or proliferative synovial tissue

Distended hypoechoic bursa

– Thickened wall ± internal septation ± hemorrhage

Acute bursitis: Thin-walled bursa distended with hypoechoic fluid, peribursal hyperemia

Chronic cases: Greater thickening of bursal wall, more mature synovial proliferation, more echogenic content, & increased likelihood of intrabursal hyperemia

– May simulate abscess or soft tissue mass

– Especially for olecranon & ischiorectal bursa
• Subacromial-subdeltoid bursitis

Associated with tendinosis, tendon tears, & impingement

Fluid collects in dependent positions

– Lateral aspect of greater tuberosity, over bicipital groove, near coracoid, & deep to acromion

Bursal wall thickening & hyperemia generally not featured

– If present, consider inflammatory arthropathy & check for rice bodies (uncommon)
• Olecranon bursitis

Common site for crystal deposition (echogenic foci within distended bursa)
• Ischial tuberosity bursitis: Large, irregular bursa with moderate wall thickening ± internal septa ± debris
• Iliopsoas bursitis: Large bursa beneath musculotendinous portion of iliopsoas muscle, anterior to hip joint capsule

Usually associated with hip arthropathy, e.g., inflammatory arthropathy or osteoarthritis
• Trochanteric bursitis: Uncommon

Most cases of trochanteric pain syndrome due to gluteus medius, minimus tendinosis, or tears
• Semimembranous bursitis: May become inflamed due to impingement against osteophytes over medial aspect of tibial plateau
• Pes anserinus bursitis: Large, distended bursa indented by 3 tendons (looks like goose foot)

Prone to synovial proliferation
• Prepatellar bursitis: Often just subtle, hypoechoic, ill-defined band in prepatellar tissues

Usually due to repetitive trauma from kneeling (e.g., housemaid, carpet layer)

Occasionally infected (penetrating trauma)
• Infrapatellar bursitis: Similar to prepatellar bursitis but located more distally
• Retrocalcaneal bursitis: Small amount of fluid in retrocalcaneal bursa is seen in 35% of normal subjects

Larger amount of fluid, bursal wall thickening, synovial proliferation, & peribursal or intrabursal hyperemia are indicative of bursitis

Nearly always associated with Achilles tendinosis

MR Findings

• T1WI

Homogeneous decreased signal intensity mass at typical location
• T2WI

Fluid-filled sac

± inflammatory debris (isointense) or, less commonly, calcification (hypointense)

± rice bodies (fibrin nodules, T1 & T2 hypointense)
• T1WI C+

± immediate bursal wall enhancement with delayed enhancement of bursal content

Imaging Recommendations

• Best imaging tool

US

Most bursae accessible to US

– Facilitates US-guided aspiration or injection
• Protocol advice

High-resolution (> 10 MHz) linear transducer for superficial bursae

– Lower resolution (~ 7 MHz) for deeper bursae

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Tags: Diagnostic Ultrasound Musculoskeletal

Apr 9, 2020 | Posted by admin in MUSCULOSKELETAL IMAGING | Comments Off

KEY FACTS

Terminology

TERMINOLOGY

Synonyms

IMAGING

General Features

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Bursitis

Bursitis

Imaging

Top Differential Diagnoses

Clinical Issues

Diagnostic Checklist

Definitions

Radiographic Findings

Ultrasonographic Findings

MR Findings

Imaging Recommendations

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Bursitis

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