Some 30 per cent of anterior cruciate ligament (ACL) tears heal within two years without knee surgery. This finding challenges the long-standing assumption that these ligaments won鈥檛 mend themselves if ruptured, and letting the injuries heal without surgery could be an option for some people.
The ACL straddles the knee to connect bones in the leg 鈥� the tibia in the shin to the femur in the thigh. Injuries to it are common in some sports, especially those that involve sudden changes of direction, such as football (soccer) or tennis.
Reconstructive surgery is often done to replace a torn ACL and stabilise the knee. Studies show, however, that around two-thirds of young people who undergo these reconstructions , and one in four .
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Fortunately, mounting evidence suggests that rehabilitating ACL injuries with exercise might work in some cases. New work by at the University of Melbourne, Australia, and her colleagues has found that with rehabilitation alone, a much larger fraction of torn ACLs appear to heal than expected.
The team analysed MRI scans to examine rates of healing among active adults in Sweden, aged between 18 and 35 years, who had completely ruptured an ACL.
Participants in the randomised trial either received surgery to replace their ACL or had rehabilitation.
Sixteen people in the group of 54 who managed their injury only with strengthening exercises had some degree of healing within two years. Their scans showed that the ligament had regrown to form one continuous length, albeit a bit thicker or thinner.
Signs of ACL healing were visible on some MRI scans from people in this group as early as three months after injury.
鈥淚t appears that ACLs can heal to varying degrees and in different ways,鈥� says Filbay.
Daniel Belavy at Bochum University of Applied Sciences in Germany says the study alone won鈥檛 be enough to change clinical practice, but provides solid evidence that torn ACLs can heal. 鈥淚t gets harder to deny the evidence when the evidence piles up,鈥� he says.
Larger MRI studies might help physicians predict at the three-month mark which ACL tears are likely to heal and who needs surgery, says Filbay. Healing could depend on , if it has been ripped off the bone, whether the ruptured ends are aligned or if the torn tissues have been dislodged, she suggests.
Filbay is also exploring whether using a brace that holds the injured knee at 90 degrees and pushes the torn ligament back together promotes healing. Preliminary findings from the first 80 participants testing the knee brace indicate that about 90 per cent of people had signs of healing three months after injury.
British Journal of Sports Medicine
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