Meniscal tears

Meniscal tears are injuries to the meniscus, C-shaped fibrocartilaginous structures acting as cushions between the femoral condyles and tibial plateau. Meniscal tears can be partial or complete and can be caused by trauma (from non-contact sports) or degeneration (such as osteoarthritis).

The pathophysiology of meniscal tears involves disruption of the meniscal tissue, resulting from acute trauma or degeneration. Traumatically torn menisci possess a higher degree of degeneration than intact menisci, suggesting that patients with a traumatic meniscal tear may already have had a certain degree of meniscal degeneration. On a molecular level, traumatic meniscus tears exhibit a higher inflammatory/catabolic response as evidenced by higher levels of chemokine and matrix metalloproteinase expression than degenerative tears.

Risk factors for meniscal tears include advanced age, sports participation (especially pivoting sports such as basketball, soccer, and football), certain occupations associated with kneeling and squatting, and higher BMI. Traumatic meniscal tears are often associated with concomitant ACL injuries. Knee osteoarthritis is the most important risk factors for degenerative meniscal tears.

The clinical course of meniscal tears often involves symptoms such as knee pain, swelling, and mechanical symptoms such as locking, popping, catching, or buckling. Physical examination often reveals posterior knee pain with deep flexion, knee effusion, joint line tenderness, limited ROM, and signs of trauma. Specific diagnostic tests include McMurray test, Thessaly test, Apley grind test, bounce home test, anterior drawer test, and medial-lateral grind test.

The prognosis of meniscal tears depends on factors such as tear location, size, and chronicity. While many tears can be managed conservatively, larger, unstable tears may require surgical intervention for optimal outcomes. The failure rate of meniscal repair at 5 years is reported to be 22.3-24.3%. Meniscal tears managed conservatively and total meniscectomy are associated with an increased risk of developing arthritic changes on imaging.