Young Athletes Who Suffer An ACL Injury Are Prone to Repeated Knee Injuries

For a young athlete, that sickening “pop” often heard when an anterior cruciate ligament (ACL) is torn can be the start of a long road back to their sport as well as a future of knee problems. While most make it back from the 8-10 months of rehabilitation, new studies show that there is a good chance that either they will require another knee surgery or suffer another injury soon after.

One factor that seems to drive future problems is the age at the first injury. The younger the athlete, the more likely there will be complications or risk of re-injury in the future. Emily Dodwell, MD, MPH, a pediatric orthopedic surgeon at Hospital for Special Surgery in New York City, recently completed an exhaustive review of the Statewide Planning and Research Cooperative System, a medical database used in New York State, to see how often an ACL surgery is followed by a second related surgery.

Between 1997 and 2010, for patients under the age of 21, there were 23,912 primary pediatric ACL reconstructive surgeries. Of those patients, 8.2% had another ACL surgery in a median time lapse of 1.6 years. In addition, 14% had a non-ACL but related knee surgery within 1 to 3 years.

As surprising as those stats are, they may still underestimate the injury recurrence rate as the data do not include injured patients who chose not to have surgery.

"The increasing rate of ACL injuries is concerning, although not surprising given greater participation in sports," said Dr. Dodwell. "For young people who have primary surgery to reconstruct a torn ACL, it is troubling that they have relatively high rates of subsequent ACL reconstruction or surgery for another knee injury. Further research is needed to determine factors associated with subsequent injury and surgery so we can implement strategies to keep our youth safe while engaging in sports.”

The study, presented at the annual meeting of the Pediatric Orthopaedic Society of North America, concluded that this increase in knee injuries comes from starting sports at a younger age, at a higher intensity and duration within a single sport.

An ACL injury at an early age also increases the chances of another injury later in life, according to a separate study. Justin P. Roe, MBBS, FRACS, from North Sydney Orthopaedic and Sports Medicine Centre presented his findings at the American Orthopaedic Society for Sports Medicine's (AOSSM) Specialty Day.

He looked at a group of 104 females and 138 males under the age of 18 who had an ACL repair surgery.

"We examined survey data from 242 patients who underwent ACL reconstruction between 1993 and 1998," said Roe. "Of this group, 75, or 31% sustained a further injury after at least 15 years."

More research is trying to find out if there are skeletal or physiological factors that may contribute to repeat injuries or if the first injury permanently weakens the knee ligaments.

"Our study shows that young knees are more prone to reinjury than the adult population when compared to other research in this area -- and is the first study to examine the incidence and risk factors for further ACL injury in a solely juvenile population over the long term," said Roe. "While surgery still may be the best option for many ACL injuries, it brings to light the important factors physicians must consider when treating the younger population."