Predicting Late Follow-up and Understanding Its Consequences in Growth Modulation for Pediatric Lower Limb Deformities

Background: Growth modulation with implants facilitates correction of angular deformities and limb-length discrepancies (LLDs) in children. Close follow-up is necessary when using growth modulation to prevent overcorrection. We examined factors associated with late follow-up and overcorrection rates in patients with late versus timely follow-up. Methods: This was a retrospective review of growth modulation procedures in children at 1 institution from 2000 through 2014. Procedures were assigned to the following categories on the basis of deformity: ankle valgus, genu valgum, genu varum, knee flexion contractures, and LLDs. Radiographic and clinical parameters were assessed. Late follow-up was defined as delaying a recommended appointment by ≥6 months. Loss to follow-up was defined as failure to return for a recommended postoperative appointment. Associations were evaluated using the following tests: χ2, Fisher exact, analysis of variance, Mann-Whitney U, and logistic regression. Statistical significance was set at P<0.05. Results: Of the 112 patients, there were 41 cases of genu valgum, 23 of ankle valgus, 18 each of genu varum and LLD, and 12 of knee flexion contractures. Twenty-two patients had late follow-up. Another 22 patients were lost to follow-up with retained implants. Patients with late follow-up had significantly higher odds of experiencing overcorrection deformities versus patients with timely follow-up (odds ratio, 19.2; 95% confidence interval, 5.2-71.4; P<0.005). The only deformity for which there was a significant difference in final alignment between patients with timely versus late follow-up was genu valgum (P<0.005). Late follow-up was associated with having a primary language other than English (P=0.05) and being obese/overweight (P=0.004). Conclusions: Late follow-up and loss to follow-up were common, occurring in 39% of patients combined. Late follow-up was associated with overcorrection in guided-growth procedures, as were overweight/obesity and primary language other than English. Level of Evidence: Level IV—retrospective case series.