RISK FACTORS FOR FAILURE FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION IN A PEDIATRIC POPULATION: A NOVEL PREDICTION ALGORITHM

BACKGROUND: Pediatric anterior cruciate ligament (ACL) reconstruction is becoming increasingly common, however, there is limited literature on the risk factors for failure in this demographic. HYPOTHESIS/PURPOSE: In the present study we sought to: 1. To determine the rate of pediatric ACL reconstruction (ACLR) failure requiring revision surgery in a nationally representative sample. 2. To determine the associated patient/injury-specific risk factors for ACLR failure. 3. To examine the differences in the rate and risks of failure between pediatric and adult patients. METHODS: Patient records were drawn from Humana individual health plans and Medicare medical records. Adult and pediatric patients who underwent primary ACLR and subsequent reoperation for either ACL revision surgery or a revision meniscal procedure between 2011-2016 were identified. Multivariate regression was used to determine the significant risk factors for ACL revision and overall reoperation rates in pediatric and adult patients. A risk algorithm was developed to predict the risk of ACL revision following pediatric ACL reconstruction. RESULTS: Pediatric patients were significantly more likely to require ACL revision within one year (OR=1.97, 95%CI 1.57-2.45, p<0.0001) and five years (OR=3.22, 95%CI 2.77-3.72, p<0.0001) following their index ACLR compared to adults. Survivorship of the index ACL procedure was significantly decreased in pediatric patients (log-rank test p<0.0001) (Figure 1). Pediatric patients were also at higher risk of sustaining a contralateral ACL tear compared to adults (5.9% vs. 1.4%, respectively, p<0.0001). Meniscus injury was a risk factor for overall re-operation (OR=2.18, 95%CI 1.67-2.89 p<0.0001) as well as ACL revision (OR=2.28, 95%CI=1.66-3.21, p<0.0001) in the pediatric cohort. This increased risk was sustained despite the type of meniscal tear intervention, with patients undergoing concurrent meniscal repair (OR=1.84, 95%CI 1.43-2.38, p<0.0001) or meniscectomy (OR=2.20, 95%CI 1.72-2.82, p<0.0001) having a higher likelihood of requiring a revision ACLR. Concomitant MCL injury but not LCL injury was a risk factor for ACL revision in this cohort (OR=1.70, 95%CI 1.31-2.19, p<0.0001). Male sex and (OR=0.78, 95%CI 0.63-0.96, p=0.0204) and being >14 years old (OR=0.62, 95%CI 0.45-0.86, p=0.0035) was associated with a decreased risk of overall reoperation. The risk algorithm demonstrated the highest probability for ACLR failure in females, less than 15 years of age, with concomitant meniscus and MCL injury, demonstrating a 36% risk of failure (Table 1). CONCLUSION: Compared to adults, pediatric patients have an increased likelihood of ACL revision surgery, contralateral ACL tears, and meniscal reoperation within 5 years of an index ACLR.