The ACL runs through the middle of the knee and stops the shin bone sliding forwards and twisting under the thigh bone. It is usually torn when the foot is planted and the knee twists or changes direction, as in football, badminton or a slip.
The two menisci are C-shaped cartilage cushions that spread load across the knee. In younger people they tear with a twist on a bent knee. From middle age onwards, they become more brittle and can tear with minimal injury, often alongside early arthritis.
A clinician examines the knee for stability and meniscus signs; tests such as the Lachman test are very sensitive for ACL tears when swelling allows.
MRI confirms ACL and meniscus tears and shows any other damage. An X-ray is used to check for fractures. In older knees, MRI often shows meniscus tears that are not the main cause of pain, so the findings are interpreted alongside the examination.
Two trials shape this approach. In the KANON trial, young active adults with an acute ACL tear who had structured rehabilitation, with reconstruction later only if needed, did as well at two years as those reconstructed early, and about six in ten avoided surgery. In a Finnish trial (Sihvonen and colleagues), keyhole trimming of a wear-related meniscus tear was no better than a placebo operation.
At VinayakM, a twisted knee is examined by an orthopaedic surgeon who treats sports and knee injuries, so the choice between rehabilitation and surgery is made on what your knee and your goals need.
Often yes, once the swelling settles. The problem is usually instability when turning or changing direction, rather than straight-line walking.
Not always. Many people, especially those who do not play pivoting sports, do well with rehabilitation. Surgery is recommended for knees that keep giving way, for pivoting sports, and when other structures are damaged.
Usually nine to twelve months, and only after strength and movement tests show the knee is ready. Returning too early increases the risk of re-injury.
Keyhole trimming does not help most wear-related tears. Tears that lock the knee, and some tears in younger people, are treated surgically, with repair preferred where possible.
ACL and meniscus injuries increase the long-term risk of arthritis. Protecting the meniscus, restoring stability where needed, and keeping the muscles strong all help.
Written in our own words. Textbooks were used as background reading and are cited; no text, figures or tables have been reproduced from them.
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