Meniscal Cysts

Question 1

Meniscal Cysts

Answer 1

local collection of synovial fluid within or adjacent to the meniscus

Question 2

Incidence of Meniscal Cysts

Answer 2

• no studies

- 1-4% of knee MRI

Question 3

Demographics

Answer 3

• MC a/w meniscal tear

- no trend in age

Question 4

Location

Answer 4

1. Perimeniscal cysts

2. Parameniscal cysts

Question 5

Perimeniscal Cysts

Answer 5

• small lesions of fluid within the meniscus

- Medial > lateral (2:1)

Question 6

Medial Perimeniscal Cysts- Location

Answer 6

posterior horn

Question 7

Lateral Perimeniscal Cysts-Location

Answer 7

anterior horn or mid-portion

Question 8

Parameniscal Cysts- eponym

Answer 8

Baker’s Cysts

Question 9

Parameniscal Cysts

Answer 9

• extruded fluid outside the meniscus (MC)

- usually located btw SM and medial head of gastroc

Question 10

Meniscal Cysts- Mechanism of Injury

Answer 10

• mensical tear fxns as a 1 way valve

- synovial fluis extrudes and then concentrates to form gel-like material

Question 11

Parameniscal Cysts- Pathoanatomy

Answer 11

horizontal and complex tears usually

Question 12

Perimeniscal Cysts- pathoanatomy

Answer 12

radial or vertical tears

Question 13

Meniscal Cysts- Associated Conditions

Answer 13

• articular cartilage injury

- ACL tear

Question 14

Meniscus Anatomy- Composition

Answer 14

• fibroelastic cartilage
• interlacing netwerk of collagen, proteoglycan and cellular elements
• composed of 65-75% water

Question 15

what is the main type of collagen in meniscus

Answer 15

90% type 1 collagen

Question 16

Medical Meniscus- shape

Answer 16

stretched out, C-shape with triangular cross section

Question 17

Lateral Meniscus- shape

Answer 17

• more circular in shape

- covers a larger articular surface compared to medial

Question 18

Medial Meniscus- blood supply

Answer 18

• medial inferior genicular artery

- supplies peripheral 20-30%

Question 19

Lateral Meniscus- blood supply

Answer 19

• lateral inferior vehicular artery

- supplies peripheral 10-25%

Question 20

Synovial Fluid- blood supply

Answer 20

• central 75% of meniscus ‘ receive nutrition through diffusion

Question 21

Symptoms

Answer 21

• asymptomatic
• pain-localized to M/L joint line or back of knee
• Mechanical sx- locking and clocking
• delayed or intermittent knee swelling
• weakness/claudication (NV impingement)

Question 22

Examination

1. inspection
2. palpation
3. motion

Answer 22

1. popliteal mass-best visualized in extension
2. joint line tenderness/palpable mass
3. crepitus

Question 23

Radiographs

Answer 23

should be normal in young pt with an acute meniscal injury or cyst

Question 24

MRI- indication

Answer 24

most sensitive diagnostic test for meniscal cyst or tear

Question 25

MRI- findings

Answer 25

- cysts with bright T2 signal - necrotic tissue, nerve sheath tissue and pus can all resemble cysts on T2-weighted MRIS - IV contrast enhancement may be needed

Question 26

Treatment- Non-operative Mgmts

Answer 26

1. rest, NSAIDS, rehab | 2. aspiration and steroid injection

Question 27

Treatment- rest, NSAIDS, rehabilitation

Answer 27

Indications - First line for small perimeniscal and parameniscal cysts Outcomes -trial of medical therapy to observe patients pain response

Question 28

Treatment- Aspiration and steroid injection

Answer 28

Indications - isolated baker's cysts in young pt Technique - cysts drainage - u/s guided injection into the cysts Outcomes - poor outcomes in older degenerative meniscal tears with associated cysts

Question 29

Treatment- Operative

Answer 29

1. Arthroscopic debridement, cyst decompression and meniscal resection 2. cyst excision using open posterior approach

Question 30

Treatment- Arthroscopic debridement, cyst decompression and meniscal resection

Answer 30

Indications -perimensical with an associated tear that is not amendable to repair (i.e. complex, degenerative, radial tear) Technique - decompress cyst completely - perform partial meniscectomy Outcome - incomplete meniscal resection may lead to recurrence

Question 31

Treatment- Cyst excision using open posterior approach

Answer 31

Indications -symptomatic parameniscal cysts Outcomes -incomplete resection may lead to recurrence

Question 32

Technique for Cyst excisions using open posterior approach?

Answer 32

- patient prone - curved incision over popliteal fossa - Interval- medial head gastric and SM - sharp dissection of cysts margins to joint capsule