ACL Rupture in Children Information

Due to the nature of the knee joint, active children are prone to knee injuries. A torn or ruptured anterior cruciate ligament (ACL) is one of the most common type of knee injuries.

Contact sports or sports that involve swift, abrupt movements such as pivoting, stopping suddenly or changing direction quickly are the most common cause of ACL injuries.

An ACL injury can also occur when a child jumps and lands on the feet with knees straight and locked instead of flexed as this puts excessive pressure on the knee joint and can cause the rope like ACL to tear to break apart.

ACL rupture in three times more common in teenage girls than in boys. This is due to:

  • Oestrogen hormones which result in weaker collagen
  • Anatomical tight notch
  • A wider pelvis leads to altered mechanics which increases valgus stress on landing from a jump


ACL injuries can be very painful and can cause the child to be unsteady on their feet and to have difficulty walking. Depending on the age of the child and the severity of the injury, a torn ACL often requires surgery in addition to physiotherapy.



  • Pain when bearing weight on the affected leg or at rest
  • Swelling of the knee joint which can occur within 24 hours of the injury
  • There will most likely be some instability when walking and the feeling of being unstable or ‘wobbly’ on the leg along with the sensation of the knee feeling not as tight or compact as it was previously
  • Often children will report feeling and hearing a ‘pop’ sound which occurs when the ligament tears


If a child has suffered a knee injury they should stop activity immediately and seek medical attention to prevent any further injury to the knee. 

In the interim, the knee should be iced regularly for 20 minute intervals. The knee should be elevated as much as possible to reduce swelling. It is advised not to bear weight on the affected leg.