Imaging

Meniscal Tear (Knee)

Preliminary Diagnosis: Meniscal Tears (Knee)

I. What imaging technique is first-line for this diagnosis

Magnetic resonance imaging (MRI) of the knee. Routine examinations do not need contrast. In the postoperative patient, the use of intraarticular contrast may help differentiate meniscal postoperative changes from re-tears.

II. Describe the advantages and disadvantages of this technique for diagnosis of meniscal tears (knee)

Advantages

  • Diagnostic for meniscal tears.

  • Useful for the categorization of the meniscal tear configuration (horizontal/radial/vertical), extension (central/peripheral, anterior horn/body/posterior horn), and stability (stable/unstable flaps or fragments), as well as depicting compartmental chondral/osseous abnormalities and the presence of other internal derangements of the knee joint.

  • Does not include exposure to ionizing radiation.

Disadvantages

  • Expensive and time-consuming imaging modality.

  • Requires significant patient cooperation and the images are susceptible to motion artifact; uncooperative patients may need sedation.

  • Closed bore magnets may be uncomfortable for claustrophobic and obese patients.

III. What are the contraindications for the first-line imaging technique?

  • Patients with non-MRI compatible implanted devices.

  • Relatively contraindicated in pregnant women within the first trimester due to the lack of studies regarding the effect of the magnetic field on the embryo.

IV. What alternative imaging techniques are available?

  • Computed tomography with intraarticular injection of contrast (CT-arthrography).

  • Knee arthrograms (serial radiographs after intraarticular injection of contrast, with or without air).

V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of meniscal tears (knee).

CT-Arthrography

Advantages

  • Does not involve magnetic fields, representing a suitable method for patients with contraindications to MRI.

  • May be diagnostic.

Disadvantages

  • Exposure to ionizing radiation.

  • This technique is more invasive than MRI, requiring intraarticular injection of contrast media.

Knee arthrograms

Advantages

  • Does not involve magnetic fields, representing a suitable method for patients with contraindications to MRI.

  • May be diagnostic, but may require additional studies.

Disadvantages

  • Exposure to ionizing radiation.

  • This technique is more invasive than MRI, requiring intraarticular injection of contrast media.

VI. What are the contraindications for the alternative imaging techniques?

CT arthrograms

  • Contraindicated in pregnant women, especially within the first and second trimesters.

  • In patients with prior allergic reactions (e.g., itching, rash, angioedema of the throat, anaphylaxis) to iodinated intravenous contrast, one should consider the risks and benefits of CT arthrography and arthrography. These patients should be pretreated with steroids and antihistamines for a minimum of 13 hours prior to imaging.

Knee arthrograms

  • Contraindicated in pregnant women, especially within the first and second trimesters.

  • In patients with prior allergic reactions (e.g., itching, rash, angioedema of the throat, anaphylaxis) to iodinated intravenous contrast, one should consider the risks and benefits of arthrography. These patients should be pretreated with steroids and antihistamines for a minimum of 13 hours prior to imaging.

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