Re: 흔한 bursitis 점액낭염(160개 --＞ 흔한 10개 미만 점액낭) 초음파 진단

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https://www.youtube.com/watch?v=bA6XqIgSxJw

J Ultrason

. 2019 Sep 30;19(78):212–221. doi: 10.15557/JoU.2019.0032

Sonographic assessment of the anatomy and common pathologies of clinically important bursae

Slavcho Ivanoski 1,✉, Violeta Vasilevska Nikodinovska 2

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PMCID: PMC6856779  PMID: 31807327

Abstract

High-resolution ultrasonography has many advantages in the imaging of the musculoskeletal system, when compared to other imaging methods, particularly in superficial, easily accessible parts of the body. It is a perfect diagnostic tool for visualizing the most common pathologies of the musculoskeletal system, including the bursae. Inflammation of bursae is frequent, and it can mimic other diseases of the musculoskeletal system. Therefore, knowledge of normal ultrasound anatomy of the bursae, their exact location in the human body, and the sonographic signs of their most common pathologies is essential for establishing a quick and accurate diagnosis by ultrasound. Common conditions affecting bursae, leading to bursitis, include acute trauma, overuse syndromes, degenerative diseases, inflammatory conditions (rheumatoid arthritis, psoriatic arthritis, gout etc.), infections such as tuberculosis, synovial tumors and tumor-like conditions (pigmented villonodular synovitis, osteochondromatosis), and many more. This review article presents and explains ultrasound examples of the most frequent pathological conditions affecting bursae. Images include normal and pathological conditions of bursae around the shoulder joint, elbow, hip, knee, and ankle joint.

초록

고해상도 초음파 검사는

다른 영상 검사 방법과 비교할 때 근골격계 영상에서 많은 장점을 가지고 있으며,

특히 신체 표면부위나 접근이 쉬운 부위에서 더욱 효과적입니다.

근골격계의 가장 흔한 질환을 시각화하는 데 완벽한 진단 도구로,

특히 활액낭 질환을 포함합니다.

활액낭의 염증은 흔하며,

근골격계의 다른 질환과 유사한 증상을 보일 수 있습니다.

따라서

활액낭의 정상 초음파 해부학,

인체 내 정확한 위치,

가장 흔한 병리의 초음파 소견을 이해하는 것은

초음파를 통한 신속하고 정확한 진단을 위해 필수적입니다.

활액낭에 영향을 미치는 일반적인 질환으로 활액낭염을 유발하는 요인에는

급성 외상, 과사용 증후군, 퇴행성 질환, 염증성 질환(류마티스 관절염, 건선성 관절염, 통풍 등), 결핵과 같은

감염, 활막 종양 및 종양 유사 질환(색소성 결절성 활막염, 골연골종증) 등이 있습니다.

이 리뷰 논문은

활막낭에 영향을 미치는 가장 흔한 병리적 상태의 초음파 사례를 제시하고 설명합니다.

이미지는

어깨 관절, 팔꿈치, 골반, 무릎, 발목 관절 주변의 활막낭의

정상 및 병리적 상태를 포함합니다.

Keywords: high-resolution ultrasonography, bursa, anatomy, inflammation

Introduction

Bursae are defined as sac-like structures, normally filled with a small amount of fluid, communicating or not communicating with the adjacent joints, whose function is to reduce the friction between two anatomical structures, tendons or muscles and bones or the skin(1). Bursae can be either constant or adventitial. Constant bursae are formed during embryological development, lined with synovial cells, containing small amounts of synovial fluid, always appearing in the same, predictable and defined spots. Adventitial bursae are formed later during life, at sites of chronic friction or pressure, and are not lined with any synovial layer. There are about 160 different constant bursae in the human body(2).

Bursitis refers to the inflammation of a bursa, and it is characterized by synovial thickening, increased amount of fluid within the bursa, localized pain near the inflammation, and adjacent soft tissue swelling(3). Bursitis occurs in many pathological conditions. They include acute traumatic injury of the bursa; repetitive microtrauma; degenerative diseases; inflammatory conditions affecting synovia, most commonly rheumatoid arthritis and gout; various infections; synovial tumors or pseudotumors like pigmented villonodular synovitis, synovial osteochondromatosis, and many other pathologies(4).

Ultrasonography can be a valuable tool for the detection and eval‎uation of bursitis. Its specificity and sensitivity in the assessment of bursal pathology, especially in superficially localized bursae, is comparable to MRI(5). Normal bursae are usually barely or not visible at all using ultrasound (Fig. 1). A major ultrasound sign of bursitis is the enlargement of a bursa, with an increased amount of fluid within it, which can be anechoic in some cases. In other cases, increased echogenicity is apparent due to debris, blood in acute trauma, or puss – if infection appears. Other signs include thickening of the hyperechoic synovial wall, which can be either uniform or irregular. The latter sign is more often present in cases of chronic bursitis. Hyperechoic edema of surrounding soft tissue or lymphedema with increased vascularity on Doppler is a common sonographic sign of bursitis (Fig. 2).

소개

활액낭은 일반적으로 소량의 액체로 채워진 주머니 모양의 구조물로, 인접한 관절과 연결되어 있거나 연결되어 있지 않으며, 두 개의 해부학적 구조물, 힘줄 또는 근육과 뼈 또는 피부 사이의 마찰을 줄이는 기능을 합니다(1). 활액낭은 상수성 또는 부속성일 수 있습니다.

상수 활액낭 Constant bursae 은

태아 발달 과정에서 형성되며, 활막 세포로 덮여 있으며 소량의 활막 액체를 포함하며,

항상 동일한 위치에 예측 가능하고 명확하게 나타납니다.

부속 활액낭 Adventitial bursae 은

생애 후반에 만성적인 마찰이나 압력 부위에서 형성되며,

활막층으로 덮여 있지 않습니다.

인간 몸에는

약 160개의 다양한 상수 활액낭이 존재합니다(2).

Constant bursae are formed during embryological development, lined with synovial cells, containing small amounts of synovial fluid, always appearing in the same, predictable and defined spots. Adventitial bursae are formed later during life, at sites of chronic friction or pressure, and are not lined with any synovial layer. There are about 160 different constant bursae in the human body(2).

활액낭염은

활액낭의 염증을 의미하며,

활액막의 두꺼워짐,

활액낭 내 액체 양의 증가,

염증 부근의 국소적 통증,

주변 연부 조직의 부종(3)이 특징입니다.

Bursitis refers to the inflammation of a bursa,

and it is characterized by synovial thickening,

increased amount of fluid within the bursa,

localized pain near the inflammation, and

adjacent soft tissue swelling

활액낭염은

다양한 병리적 상태에서 발생합니다.

이에는

활액낭의 급성 외상성 손상; 반복적인 미세 외상; 퇴행성 질환;

활막을 침범하는 염증성 질환(가장 흔히 류마티스 관절염과 통풍);

다양한 감염; 활막 종양 또는 가성 종양(예: 색소성 융모결절성 활막염, 활막 골연골종증) 및

기타 많은 병리학적 상태가 포함됩니다(4).

초음파 검사는

활액낭염의 진단 및 평가에 유용한 도구입니다.

활액낭 병변의 평가에서,

특히 표면적으로 국소화된 활액낭의 경우,

초음파의 특이도와 민감도는 MRI와 유사합니다((5)).

정상적인 활액낭은

초음파로 거의 또는 전혀 보이지 않습니다(그림 1).

활액낭염의 주요 초음파 소견은

활액낭의 확대와 내부 액체 양의 증가로,

일부 경우 무반향성으로 나타날 수 있습니다.

다른 경우 급성 외상 시 잔여물, 혈액, 또는 감염 시 고름으로 인해

반향 증가가 관찰될 수 있습니다.

다른 소견으로는

고에코성 활막 벽의 두꺼워짐이 있으며,

이는 균일하거나 불규칙할 수 있습니다.

후자의 소견은 만성 활액낭염에서 더 자주 관찰됩니다.

주변 연부 조직의 고에코성 부종 또는

도플러에서 혈관 증가를 동반한 림프부종은 활액낭염의 흔한 초음파 소견입니다(그림 2).

Fig. 1.

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Normal subacromial-subdeltoid bursa. There is a minimal amount of anechoic fluid within the bursa (arrows), located between the deltoid muscle (D) and the supraspinatus muscle tendon (arrowhead). H-humeral head

정상적인 견갑하-삼각근 하부 활액낭. 활액낭 내부에 최소량의 무음성 액체(화살표)가 존재하며, 이는 삼각근(D)과 상완골두 건(화살표 머리) 사이에 위치해 있습니다. H-상완골두

Fig. 2.

Bursitis.

Prepatellar bursa is filled with fluid, debris, and irregular synovia (arrows). Hyperechoic edema of surrounding soft tissue can be noted. Inflammation of the superficial part of the patellar ligament is also visible (arrowhead). P-patella

활액낭염. 

슬개골 전방 활액낭에 체액, 잔여물, 불규칙한 활액막(화살표)이 채워져 있습니다. 

주변 연부 조직의 고에코성 부종이 관찰될 수 있습니다. 

슬개골 인대의 표면 부분의 염증이 또한 관찰됩니다(화살표 머리). 

P-슬개골 

Recent advances in ultrasound imaging could further improve the detection of bursal pathology, and delineate very small fluid collections, undetectable with conventional ultrasound methods. Several techniques of ultrasound elastography, a qualitative or quantitative method that uses mechanical stress applied to the tissue, and causes changes dependent on elastic tissue properties, show promising results for bursal disease diagnosis.

Cases of retrocalcaneal, subacromial-subdeltoid or deep infrapatellar bursae can be detected as small, soft areas, compared to nearby tendons presenting as stiff zones using ultrasound elastography(6).

The purpose of this review article is to demonstrate the anatomical localization of clinically most important bursae of the upper and lower extremity using high-resolution ultrasonography, and to explain the ultrasound diagnosis of the most frequent and clinically most important pathologies of bursae.

초음파 영상 기술의 최근 발전은 활액낭 질환의 진단 정확도를 더욱 향상시킬 수 있으며, 전통적인 초음파 방법으로는 탐지할 수 없는 매우 작은 체액 집적을 명확히 구분할 수 있습니다. 초음파 탄성 촬영술은 조직에 기계적 스트레스를 가해 탄성 조직의 특성에 따라 변화가 발생하는 정성적 또는 정량적 방법으로, 활액낭 질환 진단에 유망한 결과를 보여줍니다. 

후경골, 견갑하-삼각근하 또는 심부 슬개골하 활액낭의 경우, 초음파 탄성 촬영술을 통해 주변 힘줄이 경직된 영역으로 나타나는 것과 대비되어 작은 부드러운 영역으로 검출될 수 있습니다(6). 

이 리뷰 논문의 목적은 

상지 및 하지에서 임상적으로 가장 중요한 활액낭의 해부학적 위치를 고해상도 초음파를 사용하여 보여주고, 

활액낭의 가장 흔하고 임상적으로 중요한 병리의 초음파 진단을 설명하는 것입니다. 

Imaging findings

Shoulder

Subacromial-subdeltoid bursa is clinically the most important bursa of the shoulder. However, there are also several other bursae around the shoulder joint: coracobrachial bursa, subcoracoid bursae, and subscapularis subtendinous bursa(7).

Subacromial-subdeltoid bursa is the largest bursa of the human body, but the two walls of the bursa are normally only up to 2 mm apart(8). It is composed of subacromial and subdeltoid portions, which in the majority of people communicate by a connective tissue band(9). Normal subacromial-subdeltoid bursa is localized between the rotator cuff tendons and the deltoid muscle, and the rotator cuff tendons and the acromion.

For the best representation of the bursa by ultrasound, the patient’s hand should be resting on the iliac wing, while the arm should be positioned posteriorly. The transducer should follow the long axis of the supraspinatus tendon (Fig. 3A). The bursa is normally visible on the ultrasound scan as a thin, linear, anechoic structure between hyperechoic peribursal fat, but the synovia is not apparent on ultrasound(8) (Fig. 3B).

영상 소견 

어깨 

영상 소견 어깨 견봉하-삼각근 하 점액낭은 

임상적으로 어깨에서 가장 중요한 점액낭입니다. 

그러나 어깨 관절 주변에는 여러 개의 다른 점액낭이 있습니다: 

견갑골-상완골 점액낭, 견갑골 하 점액낭, 견갑골 하 점액낭(7). 

견봉하-삼각근 점액낭은 인체에서 가장 큰 점액낭이지만, 

점액낭의 두 벽은 일반적으로 2mm 정도밖에 떨어져 있지 않습니다(8). 

이 점액낭은 견봉하부 및 견갑하부 부분으로 구성되어 있으며, 대부분의 경우 결합 조직 밴드로 연결되어 있습니다(9). 정상적인 견봉하-견갑하 점액낭은 회전근개 힘줄과 삼각근, 그리고 회전근개 힘줄과 견봉 사이에서 국소화되어 있습니다.

초음파로 점액낭을 가장 잘 표현하려면

환자의 손은 장골 날개에 올려놓고

팔은 뒤로 젖혀야 합니다.

트랜스듀서는 상근 힘줄의 장축을 따라야 합니다(그림 3A).

점액낭은 일반적으로 초음파 스캔에서

고에코성 점액낭 주위 지방 hyperechoic peribursal fat 사이의 얇고 선형적인 무에코 구조로 보이지만,

활액은 초음파에서는 보이지 않습니다(8) (그림 3B).

https://www.e-ultrasonography.org/upload/jksmu-25-3-109.pdf#:~:text=hyperechoic%20peribursal%20fat%20and%20deltoid%20muscle%20into,are%20represented%20as%20excrescences%20of%20the%20greater

Fig. 3.

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A. Eval‎uation of the subacromial-subdeltoid bursa. Positioning of the patient and the transducer. B. Normal subacromial-subdeltoid bursa in the longitudinal plane (arrows). Arrowhead-supraspinatus tendon, H-humeral head, T-tuberculum majus, D-deltoid muscle

A. 견봉하-삼각근 점액낭의 평가. 환자와 변환기의 위치. B. 세로면에서 정상적인 견봉하-삼각근 점액낭 (화살표). 화살표-상근 힘줄, H-상완골두, T-대결절, D-삼각근

One may distinguish between communicating and non-communicating subacromial-subdeltoid bursitis(10). The most common type of subacromial-subdeltoid bursitis is the communicating variant, when the bursa interconnects with the glenohumeral joint. It occurs in cases involving a total rotator cuff tear, either traumatic or degenerative in nature (Fig. 4). Non-communicating subacromial-subdeltoid bursitis could be a result of shoulder overuse, direct traumatic blow to the bursa, osteoarthritis, rheumatoid arthritis, etc. (Fig. 5).

아크로미오-삼각근 점액낭염은

소통형과 비소통형으로 나눌 수 있습니다(10).

One may distinguish between communicating and non-communicating subacromial-subdeltoid bursitis

가장 흔한 유형의 아크로미오-삼각근 점액낭염은 소통형으로,

점액낭이 견관절과 연결되어 있습니다.

이 유형은

외상성 또는 퇴행성 성질의 회전근개 전체 파열이 있는 경우에 발생합니다(그림 4).

비소통성 견봉하-삼각근 점액낭염은

어깨의 과다 사용, 점액낭에 대한 직접적인 외상성 타격, 골관절염, 류마티스 관절염 등으로

인해 발생할 수 있습니다(그림 5).

https://pmc.ncbi.nlm.nih.gov/articles/PMC4504865/

Fig. 4.

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Communicating subacromial-subdeltoid bursitis. Communication (arrowhead) between the glenohumeral joint and the bursa (arrows) is visible through a total tear of the supraspinatus tendon. The bursa is filled with a moderate amount of hyperechoic fluid. H-humeral head

교신성 견봉하-삼각근 점액낭염. 상완골과 점액낭(화살표) 사이의 교신(화살표)이 상완골두 힘줄의 완전 파열을 통해 보입니다. 점액낭에는 적당한 양의 고에코 액체가 채워져 있습니다. H-상완골두

Fig. 5.

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Non-communicating subacromial-subdeltoid bursitis. An increased amount of fluid in the bursa (arrows) in a patient with calcifying supraspinatus tendinopathy (filled arrow). T-tuberculum majus

비소통성 견봉하-삼각근 점액낭염. 석회화 상근 건염 (채워진 화살표)이 있는 환자의 점액낭 (화살표)에 체액이 증가했습니다. T-tuberculum majus

Elbow

Two clinically important bursae are localized near the elbow. Bicipitoradial bursa, around the distal biceps tendon, and superficial olecranon bursa. Olecranon bursa is the most superficial bursa of the human body. It is positioned between the ulnar olecranon and the skin. Olecranon bursa is normally not visible on ultrasound.

To achieve the best sonographic eval‎uation of the bursa, the patient’s hand and elbow should be in 90 degrees flexion, with the palmar side of the hand facing towards the table. The transducer should be positioned in the longitudinal or transverse plane, over the olecranon of the ulna which is used as a bony landmark (Fig. 6A). Olecranon bursitis often occurs in persons with more pronounced, palpable olecranon (Fig. 6B and C). Common etiology includes a traumatic event or infection; even a minor, sometimes neglected trauma or repetitive microtrauma can lead to olecranon bursitis (also known as student’s elbow, miner’s elbow)(11). However, septic olecranon bursitis is not uncommon either, due to its superficial localization and poor vascularity, particularly in immunocompromised patients(12), occurring in about a third of patients with bursal inflammation(11). Olecranon bursa is most commonly affected by inflammation of all the constant bursae(12).

팔꿈치 임상적으로 중요한 

두 개의 점액낭이 팔꿈치 근처에 위치합니다. 

상완 이두근 힘줄 주변의 상완 이두근 점액낭과 

표면적인 오크레나 점액낭이 있습니다. 

Bicipitoradial bursa, around the distal biceps tendon, and

superficial olecranon bursa.

오크레나 점액낭은 

인체에서 가장 표면적인 점액낭입니다. 

이 점액낭은 척골 오크레나와 피부 사이에 위치합니다. 

오크레나 점액낭은 

일반적으로 초음파에서는 보이지 않습니다. 

점액낭을 가장 잘 평가하기 위해서는 

환자의 손과 팔꿈치를 90도 구부리고 

손바닥이 테이블을 향하도록 해야 합니다. 

트랜스듀서는 

뼈의 지표로 사용되는 척골의 오크레칸 위에 

세로 또는 가로로 배치해야 합니다(그림 6A). 

올레크라논 활액낭염은 올레크라논이 더 두드러지고 촉지 가능한 경우에 자주 발생합니다(그림 6B 및 C). 일반적인 원인은 외상이나 감염이며, 경미하거나 소홀히 된 외상 또는 반복적인 미세 외상도 올레크라논 활액낭염(학생의 팔꿈치, 광부의 팔꿈치라고도 함)(11)을 유발할 수 있습니다. 그러나, 점액낭의 표면적인 위치와 혈관 분포가 불량하기 때문에, 특히 면역력이 약한 환자에서(12) 점액낭염이 있는 환자의 약 3분의 1에서 발생하는 화농성 상완골 상과염도 드물지 않습니다(11). 상완골 상과 점액낭은 모든 상과 점액낭 중 염증에 가장 흔히 영향을 받는 부위입니다(12).

Fig. 6.

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A. Eval‎uation of the olecranon bursa. Positioning of the patient and the transducer. B. Superficial olecranon bursitis in the transverse plane (*). O-olecranon. C. Superficial olecranon bursitis in longitudinal plane (*). O-olecranon

Hip

There are three bursae around the trochanter major of the femur. Trochanteric bursa, which is the largest of the three, covers the lateral insertion of the medial gluteus muscle and posterior trochanteric facet. Subgluteus medius bursa is located between the tendon of gluteus medius and the lateral facet. Subgluteus minimus bursa can be found between the gluteus minimus tendon and the anterior facet of the femur(13). It is proposed that pain of the lateral hip, known as greater trochanteric pain syndrome, is in most cases a result of pathology involving gluteal tendons or the iliotibial band. Fluid within bursae is secondary to these conditions, the primary trochanteric bursitis being very rare(14).

Iliopsoas bursa is the largest bursa around the hip. For the assessment of the iliopsoas bursa pathology, the patient should be resting supine with 180° hip extension. The transducer should be positioned in the longitudinal plane, over the femoral head and femoral neck which are used as bony landmarks (Fig. 7A). The bursa should be seen between the musculotendinous part of iliopsoas muscle and the anterior capsule of the hip(15) (Fig. 7B). Iliopsoas bursa communicates with the hip joint in 15% of adults(16), and an enlarged bursa can be a consequence of hip pathology: osteoarthritis, inflammatory disease etc.(17), or primary bursitis.

고관절

대퇴골의 대퇴골두 주변에는 세 개의 점액낭이 있습니다.

세 개 중 가장 큰 대퇴골두 점액낭은

내측 둔근의 측면 삽입부와 후방 대퇴골두면을 덮고 있습니다.

중둔근 점액낭은

중둔근 힘줄과 측면면 사이에 위치합니다.

대퇴근 점액낭은

대퇴근 힘줄과 대퇴골의 전방 면 사이에 있습니다(13).

대퇴근 점액낭은

대퇴근 힘줄이나 장경근에 관련된 병리학적인 결과로 발생하는 경우가 대부분이라고 제안되고 있습니다.

점액낭 내의 체액은

이러한 상태에 이차적으로 발생하며,

일차적인 대퇴골과 점액낭염은 매우 드문 경우입니다(14).

장요근 점액낭은

고관절 주변에서 가장 큰 점액낭입니다.

장요근 점액낭의 병리를 평가하기 위해서는

환자가 180°로 고관절을 펴고 누운 자세로 휴식을 취해야 합니다.

트랜스듀서는 뼈의 지표로 사용되는 대퇴골두와 대퇴골 경부 위에 세로면으로 배치해야 합니다(그림 7A). 점액낭은 장요근의 근육과 힘줄 부분과 고관절의 전방 캡슐 사이에서 볼 수 있습니다(15) (그림 7B). 장요근 점액낭은 성인의 15%에서 고관절과 연결되어 있으며(16), 점액낭이 비대해진 것은 고관절의 병리(골관절염, 염증성 질환 등(17)) 또는 원발성 점액낭염의 결과일 수 있습니다.

Fig. 7.

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A. Eval‎uation of the iliopsoas bursa. Positioning of the patient and the transducer. B. Iliopsoas bursitis in the longitudinal plane. Enlarged, fluid-filled iliopsoas bursa (arrow) is visible deep to the ileopsoas tendon (arrowhead). An increased amount of fluid in the anterior hip recess (*)

A. 장골근 점액낭의 평가. 환자와 변환기의 위치. B. 세로면에서의 장골근 점액낭염. 장골근 힘줄(화살표)의 깊은 곳에 확대되고 액체로 채워진 장골근 점액낭(화살표)이 보입니다. 전방 고관절 오목부(*)에 액체 양이 증가했습니다.

Knee

There are several bursae around the knee. They include prepatellar, deep and superficial infrapatellar bursae, and suprapatellar bursa anteriorly to the knee; Baker’s cyst in posterior knee compartment; medial collateral ligament bursa (Fig. 8), semimembranosus–medial collateral ligament bursa, and pes anserine bursa medially; lateral collateral ligament bursa, and iliotibial bursa laterally to the knee(5).

무릎

무릎 주변에는 여러 개의 점액낭이 있습니다. 무릎 앞쪽에는 슬개골 앞, 슬개골 아래 깊은 곳 및 표면적인 점액낭이 있으며, 무릎 앞쪽에는 슬개골 위 점액낭이 있습니다. 무릎 뒤쪽의 베이커 낭종, 내측 측부 인대 점액낭(그림 8), 반막근-내측 측부 인대 점액낭, 내측의 페스 안세린 점액낭, 무릎 옆의 외측 측부 인대 점액낭 및 장경근 점액낭(5)이 있습니다.

Fig. 8.

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Medial collateral ligament bursitis. There is a large amount of anechoic fluid filling the bursa (*) between the superficial and deep layers of the medial collateral ligament. M-medial meniscus, T-tibia, F-femur

During the embryological development, the suprapatellar bursa is divided from the knee joint with a thin septum or plica, but later the plica disappears, and it normally communicates with the knee joint in over 80% of adult individuals(18). Suprapatellar bursa is situated between the intercondillar fossa of the femur and the quadriceps tendon.

For the sonographic eval‎uation of the suprapatellar bursa, the patient should rest in the supine position with 25–30 degrees knee flexion. The transducer should be positioned in the longitudinal plane, proximal to the upper pole of the patella used as bony landmark (Fig. 9). Suprapatellar bursa is enlarged in the majority of pathologic conditions affecting the knee and producing excessive fluid within the joint. Even small amounts of fluid in the suprapatellar bursa can be visualized by high-resolution ultrasound, which is comparable to MRI in the detection of fluid and synovitis both in the suprapatellar recess and the Baker’s cyst(19,20). The quantity(21), but also the quality of the effusion within the suprapatellar recess or the Baker’s cyst can be adequately assessed by ultrasonography(22). The fluid within the recess can be anechoic or hypoechoic (Fig. 10), hyperechoic, containing blood in cases of severe trauma or severe arthritis. Sometimes fat fluid level can be visible within the recess as a sign of intraarticular fracture(22) (Fig. 11).

Fig. 9.

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Eval‎uation of the suprapatellar bursa. Positioning of the patient and the transducer

Fig. 10.

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Pigmented villonodular synovitis of the knee. The suprapatellar bursa is filled with hypoechoic fluid; irregular synovial hypertrophy (arrows). F-femur, *-quadriceps tendon

Fig. 11.

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Lipohemarthrosis. A large amount of hyperechoic fluid (arrow) with fat-fluid level (filled arrow) can be visualized within the recess in a patient with plateau tibial fracture. *-quadriceps tendon, F-Femur

Baker’s cyst is the normal gastrocnemius-semimembranosus bursa, in some adults communicating with the posterior part of the knee capsule through a thin neck(23) (Fig. 12A). Baker’s cyst is located between the semimembranosus and medial head of gastrocnemius tendons. To eval‎uate its presence and pathology by ultrasound, the patient should lie prone with a fully extended knee. The transducer should be placed in the longitudinal or transverse plane, in the medial half of the popliteal fossa, centered between the semimembranosus and medial gastrocnemius tendons which can serve as anatomic landmarks (Fig. 12 B).

Fig. 12.

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A. Baker’s cyst in the transverse plane, localized between the semimembranosus tendon (arrow) and the medial head of the gastrocnemius muscle (arrowhead). The cyst is communicating with the knee joint through a thin neck. F-Femur. B. Eval‎uation of Baker’s cyst. Positioning of the patient and the transducer. C. Baker’s cyst in the longitudinal plane. Several ossified bodies (arrows) can be seen within the cyst due to secondary osteochondromatosis

Its presence is often related to knee effusion, and it occurs in about 40% of patients with mass lying posterior to the knee(24). The cyst enlarges frequently in cases of knee overuse, osteoarthritis of the knee, arthritis, pigmented villonodular synovitis, synovial osteochondromatosis (Fig. 12C) etc. Rupture of a Baker’s cyst with synovial fluid leakage in the calf is the most common and very painful complication. In case of Baker’s cyst rupture, there is a free soft-tissue fluid around the cyst visible on ultrasound.

Prepatellar bursa is normally a very thin structure, filled with a minimal amount of fluid, not visible on ultrasound. It is localized between the patellar surface and the proximal part of the patellar ligament and the skin.

For the sonographic assessment of prepatellar bursitis, the patient should rest supine, with the knee in partial (25–30 degrees) flexion. The transducer should be placed in the longitudinal position, over the inferior patellar pole which is used as a bony landmark (Fig. 13). Prepatellar bursitis, also known as housemaid’s knee is a common painful condition, easily visible sonographically (Fig. 14). In the majority of cases, it is a result of chronic overuse. Less commonly, it develops as a consequence of direct traumatic blow(25). Professions involving prolonged kneeling such as floor layers, carpenters, auto mechanics, housemaids and others are especially prone to prepatellar bursitis.

Fig. 13.

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Eval‎uation of the prepatellar bursa. Positioning of the patient and the transducer

Fig. 14.

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Prepatellar bursitis (*). The prepatellar bursa is enlarged, filled with a copious amount of anechoic fluid and debris. P-patella. Arrows-patellar ligament

Superficial infrapatellar bursa is normally situated between the skin and the distal part of the patellar ligament. For the best representation of the superficial as well as deep infrapatellar bursa, the patient should lie supine, with a partially flexed (30 degrees) knee. The transducer should be in the longitudinal plane, following the fibrillar structure of the patellar ligament, just above the tibial tuberosity which could be used as bony landmark (Fig. 15). Superficial infrapatellar bursitis is also known as clergyman’s knee. In the majority of cases, it results from an acute traumatic injury (direct blow to the bursa) or chronic overuse(26) (Fig. 16).

Fig. 15.

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Eval‎uation of the infrapatellar bursae. Positioning of the patient and the transducer

Fig. 16.

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Superficial infrapatellar bursitis (arrows). There is a moderate amount of fluid accumulated superficially to the distal part of the patellar ligament (*)

Deep infrapatellar bursa is located between the inferior part of the patellar ligament and the anterior tibial surface (Fig. 15). Normal bursa in some situations can be visualized by ultrasound as a very small collection of anechoic fluid(27) posteriorly to the patellar ligament (Fig. 17). The etiology of the deep infrapatellar bursitis includes excessive sports activity, especially long-distance running and jumping (Fig. 18).

Fig. 17.

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Normal deep infrapatellar bursa can be seen as a small, triangular fluid collection (arrowhead) deep to the distal part of the patellar ligament (arrows), superficial to the tibial surface (T)

Fig. 18.

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Deep infrapatellar bursitis. A lobulated, enlarged deep infrapatellar bursa (arrows) deep to the distal part of the patellar ligament (arrowhead)

Ankle

There are two clinically important bursae near the Achilles tendon(28). The deeper, retrocalcaneal bursa lies between the distal anterior part of the Achilles tendon and the posterosuperior part of the calcaneus. Normal retrocalcaneal bursa, which is a constant bursa, can be visible on ultrasound in almost 25% of healthy individuals(27). The superficial, or also called “Achilles”, bursa is situated between subcutaneous fat tissue and the distal Achilles tendon or the calcaneal surface.

In order to eval‎uate both bursae by ultrasound, the patient should lie prone, with feet hanging over the bed. The calcaneal tuberosity can be used as bony landmark for identifying the bursae. The transducer should be positioned in the longitudinal plane, following the Achilles tendon (Fig. 19).

Fig. 19.

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Eval‎uation of the superficial and deep retrocalcaneal bursae. Positioning of the patient and the transducer

The deep retrocalcaneal bursa is more commonly affected by various inflammatory diseases, traumatic and overuse injuries than the superficial Achilles bursa. Inflammation of the deep retrocalcaneal bursa combined with insertional Achilles tendinopathy, formerly known as Haglund “impingement” syndrome(29,30), is a common type of bursitis (Fig. 20). The superficial retrocalcaneal bursa is an adventitial bursa that can form after birth as a result of chronic friction, usually in people wearing tight shoes(29).

Fig. 20.

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Deep retrocalcaneal bursitis (*) in a patient with insertional Achilles tendinopathy (arrows). The Achilles tendon is swollen, with disrupted fibrillar pattern and calcifications near the insertion. C-calcaneus

Conclusion

High-resolution ultrasonography has many advantages in the imaging of the musculoskeletal system, including the imaging of the bursae, compared to other imaging methods, particularly in superficial, easily accessible parts of the body. The main advantages of the technique include ease of use, good acceptance by the patients, low cost of the examination in comparison to other modalities such as MRI, and the possibility of side-to-side comparison. It is arguably a perfect method for diagnosing the most common pathologies of the bursae. However, good knowledge of normal ultrasound anatomy of the bursae, their exact location and the most common bursal pathologies is essential for establishing quick and accurate diagnosis by ultrasound.

Footnotes

Conflict of interest

The authors do not report any financial or personal connections with other persons or organizations which might negatively affect the contents of this publication and/or claim authorship rights to this publication.

References

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