MRI of the knee (an approach)

Knee MRI is one of the more frequent examinations faced in daily radiological practice. This approach is an example of how to create a radiological report of an MRI knee with coverage of the most common anatomical sites of possible pathology.

Systematic review

A systematic review in the MRI of the knee is essential since knee anatomy itself is rather complex, and pathologies and injury patterns are manifold and only rarely lead to an abnormality of a single structure but rather show diverse findings that might need to be addressed in further patient management ¹.

Bones

The bony structures of the knee, the pictured distal femur, the patella, and the proximal tibia as well the fibular head are assessed.

• bone marrow changes, bone tumors and tumor-like lesions

Joint space and capsule

Assessment of the following structures:

• joint space

  • joint effusion if present and possible intra-articular fragments, loose bodies, osteochondromatosis

• synovia

  • synovial thickening and/or hyperenhancement and other abnormalities such as tenosynovial giant cell tumor or lipoma arborescens

• synovial plicae

• presence of popliteal cyst (whether simple or complicated by a leak and/or rupture)

Intercondylar region

Assessment of the following structures:

• cruciate ligaments

  • cruciate ligament tears, ganglion, anterior cruciate ligament graft complications, cyclops lesions, mucoid degeneration, anomalous insertion of the medial meniscus

Medial compartment

Assessment of the following structures:

• medial femoral and tibial articular cartilage and subchondral bony structures

  • chondral and osteochondral injury, subchondral fractures and subchondral cysts, osteoarthritic changes

• medial meniscus

  • meniscal tears, floating meniscus

• medial collateral ligament

  • injuries, tears

• posteromedial corner

  • posteromedial corner injury

• pes anserinus

  • pes anserinus bursitis, tendon pathology, variant anatomy

Lateral compartment

Assessment of the following structures:

• lateral femoral and tibial cartilage and subchondral bony structures

  • chondral and osteochondral injury, subchondral fractures and subchondral cysts, osteoarthritic changes

• lateral meniscus

  • meniscal tears, hypermobile lateral meniscus

• lateral collateral ligament

  • lateral collateral ligament injury

• posterolateral corner

  • posterolateral corner injury

• iliotibial tract and anterolateral ligament

  • including Segond fracture, iliotibial band syndrome, etc.

Patellofemoral compartment

• patella, trochlea and retropatellar and trochlear cartilage

  • chondral and osteochondral injury, subchondral fractures and subchondral cysts, osteoarthritic changes

• distal quadriceps tendon

  • traumatic injury, tendinopathy, gout

• patellar tendon

  • patellar tendon rupture or patellar tendinosis, Osgood-Schlatter disease, jumper's knee, patella alta, patella baja

  • patellar tendon-lateral femoral condyle friction syndrome

• knee fat pads

  • injury of the Hoffa fat pad

  • fat pad impingement

Popliteal fossa

• Baker cyst

• nerve sheath tumor

Soft tissues

Assessment of any relevant imaged muscles and the subcutaneous fatty tissue:

• muscle injury and Morel-Lavallée lesions, pre- and infrapatellar bursitis

Common pathologies

• anterior cruciate ligament tear

• medial collateral ligament tear

• meniscal tears

• chondral and osteochondral injury

• osteoarthritis

• anterior cruciate ligament graft complications

• lateral patellar dislocation / patellofemoral instability

• subchondral insufficiency fracture

• Baker cyst

• pre- and infrapatellar bursitis