Meniscal Cysts Flashcards
Meniscal Cysts
local collection of synovial fluid within or adjacent to the meniscus
Incidence of Meniscal Cysts
- no studies
- 1-4% of knee MRI
Demographics
- MC a/w meniscal tear
- no trend in age
Location
- Perimeniscal cysts
2. Parameniscal cysts
Perimeniscal Cysts
- small lesions of fluid within the meniscus
- Medial > lateral (2:1)
Medial Perimeniscal Cysts- Location
posterior horn
Lateral Perimeniscal Cysts-Location
anterior horn or mid-portion
Parameniscal Cysts- eponym
Baker’s Cysts
Parameniscal Cysts
- extruded fluid outside the meniscus (MC)
- usually located btw SM and medial head of gastroc
Meniscal Cysts- Mechanism of Injury
- mensical tear fxns as a 1 way valve
- synovial fluis extrudes and then concentrates to form gel-like material
Parameniscal Cysts- Pathoanatomy
horizontal and complex tears usually
Perimeniscal Cysts- pathoanatomy
radial or vertical tears
Meniscal Cysts- Associated Conditions
- articular cartilage injury
- ACL tear
Meniscus Anatomy- Composition
- fibroelastic cartilage
- interlacing netwerk of collagen, proteoglycan and cellular elements
- composed of 65-75% water
what is the main type of collagen in meniscus
90% type 1 collagen
Medical Meniscus- shape
stretched out, C-shape with triangular cross section
Lateral Meniscus- shape
- more circular in shape
- covers a larger articular surface compared to medial
Medial Meniscus- blood supply
- medial inferior genicular artery
- supplies peripheral 20-30%
Lateral Meniscus- blood supply
- lateral inferior vehicular artery
- supplies peripheral 10-25%
Synovial Fluid- blood supply
- central 75% of meniscus ‘ receive nutrition through diffusion
Symptoms
- 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)
Examination
- inspection
- palpation
- motion
- popliteal mass-best visualized in extension
- joint line tenderness/palpable mass
- crepitus
Radiographs
should be normal in young pt with an acute meniscal injury or cyst
MRI- indication
most sensitive diagnostic test for meniscal cyst or tear
MRI- findings
- 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
Treatment- Non-operative Mgmts
- rest, NSAIDS, rehab
2. aspiration and steroid injection
Treatment- rest, NSAIDS, rehabilitation
Indications
- First line for small perimeniscal and parameniscal cysts
Outcomes
-trial of medical therapy to observe patients pain response
Treatment- Aspiration and steroid injection
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
Treatment- Operative
- Arthroscopic debridement, cyst decompression and meniscal resection
- cyst excision using open posterior approach
Treatment- Arthroscopic debridement, cyst decompression and meniscal resection
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
Treatment- Cyst excision using open posterior approach
Indications
-symptomatic parameniscal cysts
Outcomes
-incomplete resection may lead to recurrence
Technique for Cyst excisions using open posterior approach?
- patient prone
- curved incision over popliteal fossa
- Interval- medial head gastric and SM
- sharp dissection of cysts margins to joint capsule
