Without the essential nutrients supplied by blood vessels, healing cannot take place.The two most common causes of a meniscal tear are traumatic injury (often seen in athletes) and degenerative processes, which are the most common tear seen in all ages of patients. Meniscal tears can occur in all age groups. Traumatic tears are most common in active people aged 10–45. Traumatic tears are usually radial or vertical in the meniscus and more likely to produce a moveable fragment that can catch in the knee and therefore require surgical treatment.A meniscus can tear due to an internally or externally rotated knee in a flexed position, with the foot in a flexed position. It is not uncommon for a meniscal tear to occur along with injuries to the anterior cruciate ligament ACL and the medial collateral ligament MCL — these three problems occurring together are known as the "unhappy triad," which is seen in sports such as football when the player is hit on the outside of the knee. Individuals who experience a meniscal tear usually experience pain and swelling as their primary symptoms. Another common complaint is joint locking, or the inability to completely straighten the joint. This is due to a piece of the torn cartilage preventing the normal functioning of the knee joint.Degenerative tears are most common in people from age 40 upward but can be found at any age, especially with obesity.
However, the use of the drug continued to grow, as did the number of babies born with birth defects. In 1985 the label was updated to include a boxed warning. In early 1988 the FDA called for another advisory committee, and FDA employees prepared an internal memo estimating that around 1,000 babies had been born with birth defects due to isotretinoin, that up to around 1,000 miscarriages had been caused, and that between 5,000 and 7,000 women had had abortions due to isotretinoin. The memo was leaked to the New York Times a few days before the meeting, leading to a storm of media attention. In the committee meeting, dermatologists and Roche each argued to keep the drug on the market but to increase education efforts; pediatricians and the Centers for Disease Control and Prevention (CDC) argued to withdraw the drug from the market. The committee recommended restricting physicians who could prescribe the drug and requiring a second opinion before it could be prescribed. The FDA, believing it did not have authority under the law to restrict who had the right to prescribe the drug, kept the drug on the market but took further unprecedented measures: it required Roche to make warnings yet more visible and graphic, provide doctors with informed consent forms to be used when prescribing the drug, and to conduct follow up studies to test whether the measures were reducing exposure of pregnant women to the drug.