Pediatric ACL Injury Symptoms

• Popping Sensation: A sudden, audible or felt “pop” in the knee is a hallmark of ACL injury, often described by the athlete and sometimes heard by nearby players or coaches
• Immediate Swelling: Rapid swelling of the knee, typically developing within the first few hours and reaching maximum swelling within 24 hours of injury, is characteristic. This swelling represents hemarthrosis — blood within the joint — which is found in 10–65% of pediatric ACL tears
• Variable Pain: Pain at the time of injury may be intense, but some children report that pain diminishes significantly after the initial event — leading to a false sense of reassurance. Pain that increases in the days following the injury is common.
• Knee Instability: A sensation that the knee has shifted, given way, or feels unstable with twisting or pivoting movements. Notably, younger and less skeletally mature patients may report instability less frequently than adults.
• Difficulty Returning to Play: Most athletes are able to bear weight after an ACL tear, though weight bearing may be painful acutely. Inability to continue playing or to return to sport activities is nearly universal.
• Restricted Range of Motion: Depending on swelling and pain, children may have restricted bending and straightening of the knee in the acute phase.

In adults, the subjective sensation of knee instability is prominent and reliably reported. In children — particularly pre-pubertal patients — the sensation of instability may be absent or significantly underreported, even in the presence of a complete ACL tear. This can lead to a longer time to diagnosis and, in some cases, multiple episodes of “giving way” before the injury is formally identified. Parents and coaches should not rely on the absence of instability complaints to rule out an ACL tear.

If your child sustains a knee injury during sport with any of the above features, the following immediate steps are recommended:

• Stop Activity: Stop all athletic activity immediately and remove the child from play
• RICE Protocol: Apply ice to the knee for 20-minute intervals, and elevate the leg to reduce swelling
• Protect from Weight Bearing if Painful: If weight bearing is significantly painful, keep the child off their feet until evaluated
• Seek Medical Evaluation: Seek evaluation at an emergency department or urgent care if swelling is severe or weight bearing is impossible. For less acute presentations, contact Dr. Patel’s office directly to arrange a prompt evaluation.

Research consistently demonstrates that delayed diagnosis and delayed surgical treatment, when indicated, significantly increases secondary joint damage. ACL-injured patients managed non-operatively experience instability, lower rates of return to their pre-injury sport, and a higher incidence of meniscal tears. Studies show that these same consequences are associated with delayed surgery — meaning the window for optimal outcomes is not unlimited. Families in the Chicagoland area should seek a knee specialist with expertise in pediatric ACL injuries as promptly as possible after injury.

An MRI is essential to confirm the diagnosis. While X-rays may be obtained in the emergency setting to rule out fractures, only MRI can directly visualize the ACL and identify associated meniscal, cartilage, and bone injuries. Dr. Patel’s practice offers same-day MRI access to expedite diagnosis and treatment planning.