Msk -- Knee

Front 1

1. How many layers make up the medial collateral ligament? What is located between the layers?
2. How are injuries of the MCL graded?
3. What is a Pellegrini-Stieda lesion?

Back 1

1. There are two layers: the tibiocollateral ligament (superficial layer) and the meniscofemoral and meniscotibial ligaments (deep layer). A small bursa exists between the superficial and deep layers of the MCL.
2.
- Grade 1 strain: perifascicular edema paralleling the tibiocollateral ligament with preservation of its morphology.
- Grade 2 strains: partial ruptures. Thickening of the ligament from edema and hemorrhage, perifascicular edema, and displacement of the ligament fibers
from the bony attachment.
- Grade 3 strains: complete rupture. Loss of ligament continuity, disruption of the capsular ligaments, and edema extending to the adjacent subcutaneous fat.

There is often an associated joint effusion, and occasionally a "kissing" bone contusion pattern involving the lateral femoral condyle and lateral tibial plateau.
3. Posttraumatic calcification-ossification of the proximal attachment of the MCL.

Front 2

1. What is Jumper's knee?
2. What are the imaging findings of Jumper's knee?
3. What is a useful finding that differentiates Jumper's knee from patellar tendon tear?

Back 2

1. Chronic patellar tendinosis. It is a degenerative process. There is a conspicuous absence of inflammatory cells.
2. Focal thickening and abnormal signal intensity involving the proximal third of the patellar tendon. The posterior tendon margin is usually indistinct, and it may be associated with edema in Hoffa's fat pad.
3. Involvement of the anterior fibers does not occur in Jumper's which can be useful in differentiating tendinosis from acute tears of the proximal patellar tendon.

Front 3

1. What is the DDX of a cystic structure located at the level of the joint line?
2. What is the etiology of a meniscal cyst?
3. What is a cruciate ganglion cyst?

Back 3

1. Meniscal cyst, ganglion cyst, synovial cyst, bursitis (pes-anserine).
2. Mensical cyst is caused by decompression of synovial fluid through a meniscal tear. It is seen after meniscectomy, trauma, or degeneration of a meniscus. Size of a meniscal cyst may change with different knee positions.
3. Well-defined, multilocular lesion arising from either the posterior or the anterior cruciate ligament. The ACL ganglion cyst can cause fusiform thickening of the ACL.

Front 4

1. What is the classic bone contusion pattern of ACL tears?
2. What radiographic findings are associated with an ACL tear?

Back 4

1. Lateral femoral condyle and posterolateral tibia is nearly pathognomonic of a complete ACL tear. This contusion pattern occurs when the femur externally rotates on a fixed tibia.
2.
- Deep lateral notch sign: sulcus deeper than 1.5 mm. When the ACL ruptures, there is impaction of the articular surface of the lateral femoral condyle against the posterolateral aspect of the tibia.
- Chip fracture of the posterolateral cortex of the proximal tibia created by shearing forces during subluxation of the femur
- Avulsion of the anterior tibial spine at the attachment of the ACL
- Avulsion of the lateral tibial cortex at the attachment of the lateral capsular ligament (Segond fracture)

Front 5

What are the MRI findings of a bucket handle tear?

Back 5

1. Double PCL sign:
- displaced intercondylar fragment lies inferior to the PCL, parallel ing the orientation of the PCL.
- Only seen with medial meniscal tears.
2. Flipped meniscus:
- When the peripheral fragment displaces anteriorly, it becomes juxtaposed to the anterior horn, giving the appearance that the meniscal horn has a "piggyback" companion.
- Accompanies an "absent meniscus" sign.

Front 6

1. What are the types of femoral stress fractures involving the femoral neck?
2. Where do compressive stress fractures occur and what is their prognosis?

Back 6

1. Femoral stress fractures are classified as compressive or tensile.
2. Compressive stress fracture:
- occur at the base of the femoral neck in the medial aspect of the bone.
- more common than tensile stress fracture
- commonly seen in athletes
- look for focal fusiform thickening of the periosteum caused by callus formation mimicking an osteoid osteoma.
- usually do not displace and can be treated with non-weight bearing.
3. Tensile stress fracture:
- tend to occur in older pts, especially in those with Paget's disease.
- occurs in the superior cortex of the femoral neck
- commonly progresses to a complete fracture, therefore, treated with internal fixation.

Front 7

1. What are the components of the extensor mechanism of the knee?

Back 7

1.
- Tendons of the quadriceps femoris muscles
- Patella and patellar tendon
- Patellar retinacula
- Tibial tubercle

Front 8

1. What is iliotibial band syndrome?
2. What are the MRI findings?

Back 8

1. Overuse syndrome caused by irritation of the ITT from repeated flexion and extension when it repeatedly rubs over the epicondylar prominence of the distal femur.
2.
- Fluid collection or edema in the soft tissues deep to the ITT, either directly over or slightly posterior to the epicondylar prominence of the lateral femoral condyle.
- Edema in the subcutaneous fat superficial to the ITT.
- Thickening of the ITT is a finding that is compatible with chronic disease.

Front 9

When given an axial view through the patella, how do you know what side is medial or lateral?

Back 9

1. Medial facet is more acutely angled. Lateral facet is more horizontally oriented and longer.

Front 10

1. What tendons comprise the pes anserine?
2. Where do they insert?
3. What structure separates the pes anserine tendons from the medial collateral ligament?
4. What is the DDX of cystic structure in the medial aspect of the knee?

Back 10

1. Say Grace before Tea: Sartorius, Gracilis, and semiTendinosis.
2. Posteromedial aspect of the proximal tibia.
3. Pes anserine bursa which is located deep to the sartorius muscle and superficial to the medial collateral ligament and the semimembranosus. Internal septations within the bursa are common. Chronically, it may lead to erosive changes in the medial tibia.
4. Meniscal cyst, ganglion cyst, synovial cyst, semimembranosus bursa, and pes-anserine bursitis.

Front 11

1. How is the ACL recontruction procedure done?
2. How do you determine placement of the femoral tunnel?
3. How do you determine placement of the tibial tunnel?
4. What is the most common cause of impingement?
5. What are the MRI findings of impingement?

Back 11

1. Central third of the patellar tendon is resected with bone plugs at each end. This graft is secured in bone tunnels in the posterolateral femur and anterior tibia by screws.
2. On a lateral radiograph, the femoral tunnel should be positioned at the intersection of Blumensaat's line (intercondylar roof) and posterior femoral cortex.
3. The position to the tibial tunnel should be entirely posterior and parallel to the tibial intersection of Blumensaat's line when the knee is in full extension.
4. Tibial tunnel is placed too anteriorly on the tibia.
5. Increased SI in the graft at the point of impingement.

Front 12

1. What are the two bands of the PCL and what are their functions?

Back 12

1. It is composed of two important bands; the anterolateral band that tightens when the knee flexes and the posteromedial band that tightens when the knee extends.

Front 13

1. What is the most common type of patellar dislocation?
2. What are the MRI findings in lateral patellar dislocation?
3. What should you assess when there is a patellar dislocation?

Back 13

1. A lateral patellar dislocation is the most common type of patellar dislocation and occurs when there is forced internal rotation of the femur on a fixed, externally rotated tibia with the knee in flexion.
2. Bone contusion on the medial facet of the patella and lateral aspect of the lateral femoral condyle with disruption of the medial patellar retinaculum.
3. Look for osteochondral defect and assess for trochlear groove hypoplasia.

Front 14

1. What is Hoffa's disease?
2. What is the MRI appearance?

Back 14

1. Painful condition caused by one acute traumatic episode or repetitive trauma to the anterior knee that produces hemorrhage and necrosis in the fat pad.
2.
- Intense edema within the infrapatellar fat pad during the acute phase of the disease. Bowing of the patellar tendon from mass effect may be evident.
- When the condition is chronic or subacute, fibrin and hemosiderin
depositions affect the signal intensity in the fat, producing regions of low signal intensity on T1W and T2W images.

Front 15

What is localized anterior arthrofibrosis (cyclops lesion)?

Back 15

1. Complication of arthroscopic acl repair. Look for nodular mass in the anterior joint recess adjacent to the ACL graft.

Front 16

What are the bone findings in hypothyroidism in kids?

Back 16

- Markedly delayed bone maturation especially involving the carpus.
- brachycephaly
- enlarged sella turcica
- wormian bones
- scfe
- epiphyseal fragmentation

Front 17

1. What processes affect the medial tibial metaphysis?
2. What is the erosive change on the medial side of the proximal tibial metaphysis in syphilis called?
3. What are the imaging findings in Blounts disease?

Back 17

1. Blounts disease and Syphilis.
2. Wimberger sign (moth eaten appearance of the medial aspect of the proximal tibial metaphysis).
3.
- Beak-like appearance of the proximal tibial metaphysis.
- Irregular, widened down-sloping physis
- Poorly formed and down-sloping medial epiphysis.
- Overgrowth of cartilage overlying the medial tibial plateau
- Enlargement of the medial femoral condyle.
- Varus deformity of tibia (resulting in bow-leggedness).

Front 18

1. What are the imaging findings of Blount's disease?
2. What physiologic process can give similar findings?

Back 18

1.
- AKA tibia vara
- local growth disturbance of the medial proximal tibial epiphysis.
- abrupt angle at the beaked medial tibial metaphysis.
- MRI may show articular cartilage hypertrophy, angulation, and and an enlarged medial meniscus.
2. Normally as toddlers begin to walk their bones will bend medially, a phenomenon known as physiologic bowing. The bowing will normally resolve, in contrast to tibia vara, which progresses to increasing varus deformity.

Front 19

Spontaneous osteonecrosis of knee (SONK)

Back 19

- Affects the medial femoral condyle.
- Affects middle aged to elderly pts. OCD affects younger pts.
- Location is different than OCD which affects the lateral aspect of the femoral epicondyle.

Front 20

Pelligrini-Stieda disease

Back 20

Heterotopic ossification at site of proximal MCL from prior injury