Comparison of Growth Plate Violations for Transtibial and Anteromedial Surgical Techniques in Simulated Adolescent Anterior Cruciate Ligament Reconstruction

Background: Increases in the rates and intensity of youth sports participation have led to an elevated incidence of anterior cruciate ligament (ACL) injuries and reconstruction in adolescents. Traditional reconstruction techniques in the skeletally immature patient may violate the growth plates and potentially lead to deformities. Hypothesis/Purpose: The purpose of this study was to compare the volume and location of femoral growth plate violations resulting from anteromedial (AM) and transtibial (TT) techniques in ACL reconstruction. The hypothesis was that the more oblique angle used in femoral tunnels drilled with the AM portal technique would produce larger and more lateral violations compared with those resulting from TT tunnels. Study Design: Controlled laboratory study. Methods: Growth plate disturbances were quantified by performing simulated reconstructions in computer models created from magnetic resonance imaging scans of the knees of 17 adolescent participants. Locations of tunnels drilled with simulated AM and TT portal techniques were specified by an orthopaedic surgeon blinded to the locations of the femoral physes in the knee models. Tunnels with lengths of 20, 25, and 30 mm were placed in each model using simulated drill diameters of 7, 8, and 9 mm in addition to a 4.5-mm tunnel breaching the lateral cortex. Normalized measures of the volume and laterality of violations were computed. Results: Tunnels drilled with the AM portal technique disrupted a significantly larger percentage of the physis (P =.007), but the difference was not substantial. Tunnels drilled with the AM portal technique produced violations that were more lateral in the physis than those drilled with the TT technique (P <.001). Tunnels drilled with the AM portal technique resulted in mean violations that were 5.1% ± 2.1% of the physis as compared with 4.7% ± 2.0% for TT tunnels. The mean value for a normalized measure of the laterality of the violation (L score) was 0.590 ± 0.115 for tunnels drilled with the AM portal technique and 0.290 ± 0.104 for TT tunnels. The AM approach produced 16 of 153 simulated reconstructions with growth plate violations greater than 8% compared with only 10 with the TT approach. Conclusion: Results suggest that the AM approach produces growth plate violations that are larger and more lateral than the violations generated using the TT technique. AM approaches were more likely to remove more than 8% of the physeal volume, a level previously identified as posing a greater risk of growth disturbances. While the difference in the mean physeal volume removed between the approaches was small, the violations for the AM approach were much more lateral, a finding of potentially greater clinical significance. Clinical Relevance: As progressively younger patients are considered candidates for ACL reconstruction, knowledge of how variations in technique affect the developing knee is critical to preventing iatrogenic injuries.