Meniscus Injury

Key Features

• Most meniscus injuries occur with acute injuries or repeated microtrauma, such as squatting or twisting

• Joint line pain and pain with deep squatting are the most sensitive signs

• Difficulty with knee extension suggests an internal derangement that should be evaluated urgently with MRI

Clinical Findings

• Injuries to a meniscus can lead to pain, clicking, and locking sensation

• Patient may have an antalgic (painful) gait and difficulty with squatting

• Effusion or joint line tenderness may be present

• Swelling usually occurs during the first 24 hours after meniscus injury

• Meniscus tears rarely lead to the immediate swelling that is commonly seen with fractures and ligament tears

Diagnosis

• The McMurray test, the modified McMurray test, and the Thessaly test can be performed to confirm the diagnosis (Table 41–6)

• Most symptomatic meniscus tears cause pain with deep squatting and when waddling (performing a "duck walk")

• Radiographs

  • Usually normal

  • May show joint space narrowing, early osteoarthritis changes, or loose bodies

• MRI

  • Best diagnostic tool for meniscal injuries (93% sensitivity and 95% specificity)

  • High signal through the meniscus (bright on T2 images) represents a meniscal tear