By Jordana Bieze Foster
Two large studies presented in late March at the annual meeting of the American Academy of Orthopaedic Surgeons (AAOS) added to the evidence that pediatric patients have an elevated risk of surgical revision after anterior cruciate ligament (ACL) reconstruction, and a third study suggested that returning to sports too early may be a contributing factor.
Researchers from several Kaiser Permanente Medical Group locations in southern California retrospectively reviewed more than 21,000 cases of primary ACL reconstruction and stratified them by age group. The revision-free survival rate at five years was highest in patients older than 40 years and lowest in patients aged 21 years and younger; the five-year revision rate of 9% for the latter group was 7.8 times higher than for the former.
Within the youngest group of patients, factors associated with higher risk of revision included male gender, body mass index of less than 30 kg/m2, and white race. Allografts were associated with higher risk of revision than bone-patellar tendon-bone (BPTB) autografts in all patients younger than 40 years, and hamstring autografts were associated with a higher risk of revision than BPTB autografts in those younger than 21 years.
“Understanding the age-related risk factors associated with revision after ACL reconstruction may help with patient counseling and optimal graft choice,” said Gregory B. Maletis, MD, an orthopedic surgeon at Kaiser Permanente Medical Center in Baldwin Park, CA, who presented the findings at the AAOS meeting.
In a separate AAOS presentation, researchers from the Hospital for Special Surgery (HSS) in New York City analyzed a New York State database and identified nearly 24,000 patients younger than 21 years who were at least one year removed from primary ACL reconstruction (median follow-up time, 6.7 years). They found that 8.2% of those patients had undergone additional ACL reconstructions and 14% had undergone additional non-ACL knee surgery. The side of the operation was not noted in the database, so it is unclear how many of those additional ACL reconstructions were revisions of the primary reconstruction and how many involved the contralateral knee.
Risk factors associated with revision included younger age at the time of primary ACL surgery, male gender, white race, private insurance, higher hospital ACL procedure volume, and higher surgeon ACL procedure volume. Graft type and surgical technique were not noted in the database.
“Younger children may participate in more risky activities than older children, and ACL reconstruction for open physes may be less reliable than in skeletally mature patients,” said Emily R. Dodwell, MD, a pediatric orthopedic surgeon at HSS, who presented the findings at the AAOS meeting.
But a third study presented at the meeting suggests young athletes may be at higher risk for revision ACL surgery because they are returning to sports before they have recovered the functional movement skills needed to do so safely.
Researchers from Duke University in Durham, NC, assessed Functional Movement Screen (FMS) and Lower Quarter Y-Balance Test (LQYBT) performance in 39 adolescents and 16 adults who had undergone ACL reconstruction nine months earlier.
The composite FMS scores for all participants, regardless of age, were low enough to suggest an increased risk of injury based on the cutoff score of 14 published in several unrelated FMS studies. The 17 skeletally immature patients in particular scored lower on the straight leg raise (SLR) test than the skeletally mature adolescents or the adults. On the LQYBT, there was a wider range of anterior reach asymmetry in the adolescents than in the adults.
“The adolescent’s musculoskeletal system is different from the adult’s,” said Matthew J. Boyle, MD, now a pediatric orthopaedic fellow at Boston Children’s Hospital, who presented the findings at the AAOS meeting. “The SLR results probably reflect some sort of core weakness. More of a rehab focus on core strengthening would improve their scores, and hopefully improve their outcomes.”
Maletis GB, Chen J, Inacio MC, et al. Anterior cruciate ligament reconstruction: Age-related risk factors for revision. Presented at the American Academy of Orthopaedic Surgeons annual meeting, Las Vegas, NV, March 2015.
Dodwell E, McCarthy MM, Pan T-J, et al. Long term follow up of pediatric ACL reconstruction in New York State: High rates of subsequent ACL reconstruction. Presented at the American Academy of Orthopaedic Surgeons annual meeting, Las Vegas, NV, March 2015.
Boyle MJ, Butler RJ, Queen RM. Functional movement recovery after anterior cruciate ligament reconstruction in adolescent patients. Presented at the American Academy of Orthopaedic Surgeons annual meeting, Las Vegas, NV, March 2015.