Topic 6 - the knee

Question 1

What can a joint effusion of the knee indicate?

Answer 1

• Non-specific indicator of joint pathology

* May be due to trauma, inflammation, and degenerative disorders

Question 2

What is the best position to see an anterior joint effusion at the knee?

Answer 2

• This is seen best with the knee in full extension and the foot lifted off the bed.

Question 3

What can cause inflammation of the pre patellar bursa?

Answer 3

• Inflammation of the pre-patellar bursa can occur following a direct blow, or it can be seen in those people who kneel often, such as carpet layers.

Question 4

What are the two different anterior knee bursitis’?

Answer 4

• Infrapatellar bursitis, “clergyman’s knee,” is due to kneeling in the upright posture.
• Prepatellar bursitis, housemaid’s knee, results from friction due to prolonged kneeling.

Question 5

What are some indicators of anterior knee bursitis?

Answer 5

the presence of increased flow on color or power Doppler imaging or pain during transducer palpation are indicative of an inflammatory state consistent with true bursitis

Question 6

What is the fat pad deep to the patellar tendon known as?

Answer 6

Hoffa’s fat pad.

Question 7

What is the common site for pathology of the patella tendon?

Answer 7

• usual site for tendinopathy to occur is at the inferior pole of the patella involving the deep fibres of the proximal mid tendon.

Question 8

What measurements should you do if you find patella tendonopathy?

Answer 8

• Measure the abnormal area in three planes, and give a ratio of the tendon involved to the overall cross-section of the tendon.

Question 9

What is jumpers knee?

Answer 9

• clinical syndrome affecting adults, usually athletes, who are involved in sports that require repetitive violent contraction of the quadriceps muscle.
• chronic recurrent anterior knee pain and tenderness of the patellar tendon near its insertion to the patella.
• Initially the pain is present only after activity.
• Later, it may become persistent until finally the tendon ruptures

Question 10

How does jumpers knee appear on ultrasound?

Answer 10

• the proximal patellar tendon is thickened.
• A central area of low echogenicity is visible posteriorly in the tendon close to the patellar apex and suggests a primary abnormality of the osteotendinous junction.
• More discrete focal hypoechoic areas may represent small partial tears.
• Calcification or dystrophic ossification can occur within an area of chronically inflamed or damaged tendon.

Question 11

What are Sinding-Larsen-Johansson disease and Osgood-Schlatter disease ?

Answer 11

clinical syndromes that occur in adolescence and are thought to be related to traction trauma at the immature osteotendinous junctions

Question 12

What is the difference between Sinding-Larsen-Johansson disease and Osgood-Schlatter disease?

Answer 12

• Sinding-Larsen-Johansson disease affects the proximal tendon at its insertion to the patella, whereas Osgood-Schlatter disease affects the distal tendon at its insertion into the tibial tubserosity.

Question 13

What does sinding-larsen-johansson disease look like on ultrasound?

Answer 13

• Ultrasound of Sinding-Larsen-Johansson disease and jumper’s knee are similar.
• The original description of Sinding-Larsen-Johansson disease was of a condition that occurred in adolescence, whereas jumper’s knee can occur at any age.
• It is believed that Sinding-Larsen-Johansson disease is a specific type of jumper’s knee

Question 14

What is the cause of Osgood-schlatters disease?

Answer 14

• usually a history of participation in sports and a rapid growth spurt.
• The condition is bilateral in 25% of patients
• cause is thought to be traumatic in origin, resulting in avulsion of fragments of cartilage and bone from the tibial tuberosity

Question 15

How does osgood-schlatters disease present clinically?

Answer 15

there is pain, tenderness, and soft-tissue swelling over the tibial tuberosity at the site of insertion of the patelar tendon.

Question 16

What does osgood-schlatters disease look like on sonography?

Answer 16

• swelling of the unossified cartilage and overlying soft tissues
• fragmentation, and irregularity of the ossification center with reduced internal echogenicity,
• thickening of the tendon
• infrapatellar bursitis.

Question 17

What does a patella tendon tear look like on ultrasound?

Answer 17

• An acute tendon tear usually presents with sudden pain, typically after a sports injury, and can be partial or complete.
• A discrete hypoechoic focus is visible within the tendon, representing intratendinous hematoma and edema
• Although rare, complete tenndon rupture appears as a full-thickness discontinuity of the tendon.

Question 18

How do meniscal cysts present clinically?

Answer 18

• may present as a palpable soft tissue swelling centered over the joint line may change size, depending on the position of the knee, being largest when the knee is extended.
• Meniscal cysts are most often seen in association with horizontal and complex tears of the lateral meniscus
• Less commonly, they are associated with tears involving the medial meniscus

Question 19

Describe different types of tears of the MCL?

Answer 19

o Partial tears – the ligament becomes enlarged and hypoechoic with the loss of one or both of the echoic margins.
o Complete tears – fluid filled gap.
o Chronic tears – increased size, mucoid degeneration, and calcification.

Question 20

What is the function of the MCL?

Answer 20

• limits extension of the knee and is taut in the erect position

Question 21

What makes up the pes anserinus?

Answer 21

• common insertion of three tendons
o the gracilis
o Sartorius
o Semitendinosus

Question 22

How can the abnormal pes anserinus appear?

Answer 22

• The abnormal pes appears enlarged and hypoechoic, best appreciated by comparing to the asymptomatic side

Question 23

What is the function of the ITB?

Answer 23

• stabilises the knee

* assists the quadriceps in knee extension

Question 24

Where does the ITB insert?

Answer 24

• At the knee it crosses the lateral condyle and inserts into the anterior surface of the tibia at Gerdy’s Tubercle

Question 25

What is important when scanning the ITB?

Answer 25

• Comparison with the other side is important to identify minor degrees of enlargement.

Question 26

What is ITB syndrome?

Answer 26

• ITB Syndrome occurs when the tendon is inflamed by ‘snapping’ over the femoral condyle.
• This is usually a clinical diagnosis.

Question 27

What does ITB syndrome look like on ultrasound?

Answer 27

On ultrasound the ITB appears enlarged and hypoechoic.

• Look for fluid in or thickening of the bursa

Question 28

What is the function of the LCL?

Answer 28

• This prevents over-extension of the knee.

Question 29

How is the LCL different to the MCL?

Answer 29

It is separate to the joint capsule and not attached to the meniscus

Question 30

What is the function of the bicep femoris?

Answer 30

• This is the flexor of the knee joint and also an extensor of the hip when the knee is extended.

Question 31

What are the attachments of the biceps femoris?

Answer 31

• Originating from the ischial tuberosity it inserts onto the head of fibula, splaying out to form a cowl around the outside of the lateral ligament.

Question 32

What is a bakers cyst?

Answer 32

• Distension of the gastrocnemio-semimembranosus bursa in the posteromedial knee

Question 33

Where will you find a bakers cyst?

Answer 33

• The deep component lies between the medial head of gastrocnemius (MHGC) and the joint capsule
• A superficial component extends inferiorly between the muscle belly of MHGC and the skin.

Question 34

How does a bakers cyst appear on ultrasound?

Answer 34

• Look for a fluid collection just medial to the MHGC tendon

* This bursa has a characteristic ‘C’ or reversed ‘C’ shape when viewed in transverse

Question 35

What can aid in detection of a bakers cyst?

Answer 35

• flex and extend the knee several times to pump fluid through the narrow neck into the bursa and make it more obvious

Question 36

What should you look for once you have detected a bakers cyst?

Answer 36

• Look at the wall thickness, and internal contents, that is, loose bodies, debris. Is it painful on compression?
• Look for evidence of leakage, for example, pointed inferior margin, poorly defined inferior wall, hypoechoic fluid collecting down the postero-medial calf superficial to the medial gastrocnemius muscle, induration of skin and subcutaneous tissues, oedema of the adjacent muscles, tenderness in the calf due to irritant nature of the fluid.

Question 37

Why should you check for a bakers cyst during a DVT study?

Answer 37

• as an enlarged cyst or one that has leaked and ruptured can have a similar clinical presentation to a suspected DVT.

Question 38

What can low level echoes in a bakers cyst represent?

Answer 38

Low level echoes are common within Baker Cysts’ and in most occasions doesn’t represent haematoma.

Question 39

What can echogenic foci in a bakers cyst represent?

Answer 39

These echognic focii are sometimes referred to as rice bodies. The appearance of these is typical of rheumatoid but it is important to be aware that they will appear in other clinical settings.