Poster 278: Low Distal Femoral Epiphysis Height May Be a Risk Factor for Growth Disturbance Following All-inside All-Epiphyseal Anterior Cruciate Ligament Reconstruction

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Objectives: To date, no study has analyzed the relationship between epiphyseal size and the risk of clinically relevant physeal violation in skeletally immature patients who underwent all-epiphyseal anterior cruciate ligament reconstruction (ACLR). The dramatic rise in participation of children and adolescents in sport activities in the last few decades has led to a likewise dramatic increase in the number of anterior cruciate ligament (ACL) injuries diagnosed in this population. The standard adult ACL reconstruction (ACLR) is performed by drilling holes that cross the region where the physes were present on both the distal femur and proximal tibia. When this technique is performed in pediatric patients, there is concern about growth cartilage damage with potential leg length discrepancy (LLD) and limb angular deformity over time. The purpose of this study was to measure the width and height of the distal femoral epiphysis (DFE) and evaluate if a small-size epiphysis is a risk factors for growth disturbance following all-inside all-epiphyseal ACLR. Methods: A consecutive series of skeletally immature patients treated with all-inside all-epiphyseal ACLR at a single tertiary-care hospital from 2010 to 2017 were included. Intraoperative 2D imaging was used for all the patients during the procedure. Demographic, surgical, clinical and radiological data were collected; epiphyseal height and width were measured on MRI imaging. The coronal plane with the visualization of popliteus tendon was selected, and the measurements were done on this slice. The epiphyseal thickness was measured on the lateral condyle since the femoral tunnel is drilled on this part of the knee in the all-epiphyseal ACLR technique. The location of the plane with popliteus tendon insertion allows for a standardized method of measurement in the proximity of the femoral tunnel location. The enrolled patients were then divided into two cohorts based on the subsequent development of growth arrest of the distal femur during the follow-up. Growth arrest was defined as a post-surgical complication resulting in 20 mm or more of LLD and/or a progressive deformity of the lower limb that required subsequent surgical procedures. Results: Fifty-three patients were included in the analysis; 7 of them had clinically relevant growth arrest of the distal femur after all-inside all-epiphyseal ACLR and necessitated subsequent medical procedures. We found a statistically significant difference in the height of the lateral DFE between the cohort of patients that developed subsequent growth disturbances and the other cohort (21.5 ± 1 mm vs 24.0 ± 2.6 mm), (p < 0.001). There was no statistically significant difference between the 2 groups considering the epiphyseal width (72.3 ± 1.9 mm vs. 71.1 ± 5.7 mm, p = 0.3). To standardize the size of epiphyseal height involved in the drilling process in different patients, the height of the lateral DFE was then related to the diameter of the femoral tunnel drilled during reconstruction. A statistically significant difference of this ratio was found between the 2 groups (2.2 ± 0.14 vs. 2.7± 0.4, p<0.001). Conclusions: Physeal violation is a possible complication to consider when ACLR is performed in skeletally immature patients. A wide variety of surgical techniques used for pediatric ACLR have been described with the goal of providing knee stability while minimizing physeal injury and subsequent growth disturbance. Low lateral DFE height may be a risk factor for skeletal growth arrest in patients undergoing all-inside all-epiphyseal ACLR. Surgeons must be aware of this measurement when performing this technique in the skeletally immature patients with small epiphyses. Further studies are necessary to better define a DFE height threshold as a risk factor for growth disturbance.