Poster 229: Improved Epiphyseal Socket Placement with Intraoperative 3D Fluoroscopy: Consecutive Series of Pediatric All-epiphyseal Anterior Cruciate Ligament Reconstruction.

OBJECTIVES: All-epiphyseal anterior cruciate ligament reconstruction (ACLR) is a safe procedure for skeletally immature patients with ACL tears because the sockets are contained within the epiphysis and do not cross the growth plate. However, due to the undulation of the distal femoral physis, accidental disturbance of the growth plate during tunnel placement is possible. It is imperative to obtain intraoperative imaging to view the trajectory of the guide wire prior to reaming the socket. The purpose of this study was to investigate the effect of the use of 3D intraoperative fluoroscopy on socket placement in patients undergoing all-epiphyseal ACLR. We hypothesized that 3D imaging would allow for better intraoperative visualization of the growth plate and a smaller incidence of growth plate violation. METHODS: Patients under the age of 18 who underwent a primary ACLR between 2011 and 2018 by the senior authors were retrospectively reviewed. Patients that underwent an all-epiphyseal ACLR with an available postoperative MRI were included. Demographic data, surgical details and type of intraoperative fluoroscopy were collected. The minimal distances between the femoral socket and distal femoral physis (DFP) and tibial socket and proximal tibial physis (PTP) were recorded. Sockets that touched the physis or extended into the metaphysis were recorded as zero. Patients were split into two groups; a 2D imaging group that received intraoperative anterior to posterior and lateral fluoroscopic radiographs and a 3D fluoroscopy imaging group. Interrater reliability of radiographic measurements was evaluated using intraclass correlation coefficient (ICC). Statistical analysis was performed using a student’s t-test to determine differences between groups. RESULTS: 72 patients fit the inclusion criteria and were retrospectively reviewed. 54 patients had 2D imaging and 18 patients had 3D imaging. The mean age of the cohort at time of surgery was 12.3 ± 1.5 years, 79% of patients were male, and 54% tore their left ACL. The mean time from surgery to postoperative MRI was 2.0 ± 1.1 years. The ICC was 0.92 (95% CI 0.35-0.98), indicating almost perfect interrater reliability. The mean difference in distance between the tibial socket and the PTP was significantly less in the 2D imaging group than the 3D imaging group (1.2 ± 1.7mm vs 2.5 ± 2.2mm, p=0.03). (Table 1). The femoral socket touched or extended beyond the DFP significantly less in the 2D group than in the 3D group (13% vs 43%, p<0.000). CONCLUSIONS: There was a significantly decreased incidence of DFP violation with use of 3D intraoperative imaging for all-epiphyseal ACLR socket placement. Surgeons should consider utilizing 3D imaging to potentially decrease the rate of growth disturbance due to physis violation in these patients.