Myths in medicine

There are many myths in modern medicine.1 Myths are good stories that are easy to remember, and when they include a mechanical explanation for changes in pain that make intuitive sense, they catch on and live for a long time. One such story is that meniscal tears cause pain, which can be relieved by removal of the damaged meniscal tissue.1 This myth has been ‘busted’ by randomised, double-blinded trials in middle-aged and older patients demonstrating knee arthroscopy to be no better for degenerative meniscal tears than placebo surgery.2 3 But why does knee arthroscopy provide no better pain relief than placebo surgery?

Deconstructing a myth

The rationale for cutting away damaged meniscal tissue is based on the premise that the injured or damaged parts of the meniscus are the primary cause of the patient’s pain and discomfort. More likely, the knee pain is explained by the presence of early degenerative changes (including degenerative meniscal tissue) or established osteoarthritis in the knee and not because of a direct link between pain and meniscal damage per se.4 Meniscal tears are common in the symptom-free general middle-aged and older population with and without signs of radiographic knee osteoarthritis.5 6 Similarly, in patients with knee trauma, meniscal tears are frequently seen in the uninjured contralateral leg.7 Such studies debunk the explanation that meniscal tears always cause pain; the simple ‘car mechanic’ analogy—cutting tissue away—does not apply.

Meniscal tears often …