O3227: Early Postoperative Complication Following Tibial Tubercle Osteotomy in Young Patients with Patellofemoral Instability: Does Distalization Increase Risk? A Multicenter Cohort Analysis

Background: Tibial tubercle osteotomy (TTO) is a surgical technique utilized in the management of patellofemoral instability (PFI) to correct both lateralization of the extensor mechanism and patella alta. Techniques including tubercle distalization require complete osteotomy detachment and have been associated with an increased risk of complications in the literature, albeit in predominantly adult cohorts. Adolescent-only cohorts undergoing TTO are lacking. The purpose of this study is to compare two tubercle osteotomy techniques in regard to their risk of postoperative complication within a multicenter, adolescent cohort of PFI patients.

Methods: A retrospective comparative study was conducted from 2007-2021 at two large tertiary care pediatric hospitals identifying adolescent and young adult patients who presented for surgical treatment of PFI undergoing TTO. Groups were stratified base on the type of TTO: Anteromedialization in isolation (AM) and Anteromedialization with concomitant distalization (AMD). Demographics and radiographic measures including Tibial Tuberosity - Trochlear Groove (TT-TG) Distance, Caton-Deschamps index (CDI), Dejour and Oswestry-Bristol dysplasia classifications, number of dislocations, number of screws, type of osteotomy (slope or step-cut), and timing of MPFL reconstruction (staged or concurrent) were recorded. Postoperative complications were identified via chart review and recorded using the modified Clavien-Dindo-Sink (CDS) classification system. Bivariate testing was conducted to compare variables among treatment groups.

Results: Study criteria identified 125 patients undergoing tubercle osteotomy (75 AM and 50 AMD). Treatment cohorts had similar demographics, TT-TG distance and Dejour classification (Table 1). AMD had a higher CDI than AM patients (1.37±0.21 vs. 1.29±0.18, p=0.027). Slope-cut was the preferred type overstep-cut among both the cohorts of AM and AMD (p < 0.001). Mean follow up was similar between both the groups at 1.95±2.07 years in the AM group and 1.91±2.05 years in the AMD group (p=0.5). Overall complication across both cohorts was reported 19.3% of cases (n=24/125). Overall, the most common complication was Grade III in 14 patients (11.2%), followed by Grade II in 7 patients (5.5%) and Grade I in 2 patients (1.6%). Overall, 19 (15.2%) patients required a return to the OR for early postoperative complication or re-dislocation. Re-dislocation following TTO was seen in a total of 4 cases (3.2%). No significant differences between AM and AMD groups were noted with respect to grade of complication, individual complication, re-dislocation or return to OR (p >0.05) as reported in Table 2.

Conclusion: Our large multicenter cohort analysis of adolescents and young adults undergoing TTO, the overall complication rate was observed at either similar or lower to prior adult studies. Distalization did not increase the risk of complications compared to adult literature where consensus is lacking. Findings from this study serve to improve patient counseling for adolescent PFI patients undergoing TTO and demonstrate similar risk profiles between TTO techniques when distalization is being considered.