Three-dimensional transfer of tibial tuberosity for patellar instability with patella alta preserves patellar position and clinical outcomes: A minimum 3-year follow-up study

Abstract

BackgroundThe three-dimensional (3D) transfer of tibial tuberosity has been reported to improve patellofemoral congruity and showed good clinical outcomes during the short follow-up, however, little is known about whether the patellar position and clinical outcomes are preserved at longer follow-ups and the risk factors for poor clinical outcomes. HypothesisWe hypothesized that patellar position and clinical outcomes would be preserved and the predisposing factors were associated with poor clinical outcomes after the 3D transfer of tibial tuberosity. Patients and methodsThirty-nine patients, with a mean age of 27.9 (15–52) years, who underwent the 3D transfer of the tibial tuberosity were enrolled. Patellar position was evaluated using the Caton-Deschamps index and patellar tilt. Clinical outcomes were evaluated with Lysholm and Kujala scores pre- and postoperatively. Age, body mass index (BMI), radiographic measurements, and range of motion (ROM) were compared between the poor group (defined as <80 points on Kujala score) and the good group (≥80 points). The mean follow-up period was 54.1 (36–100) months. ResultsPatellar position decreased from 1.32 (1.21–1.53) preoperatively to 0.99 (0.84–1.07) at the final follow-up, according to the Caton-Deschamps index (p < 0.01). The mean patellar tilt decreased from 26.0° (21–40°) to 15.1° (5–28°) (p < 0.01). Kujala and Lysholm scales improved from 59.1 to 54.2 to 90.1 and 91.8 at final follow-up, respectively (p < 0.01). Increased BMI, lower femorotibial angle, limited ROM, and poor preoperative clinical outcomes were the predicting factors for poor postoperative clinical outcomes (p < 0.05). ConclusionThe 3D transfer for patellar instability with patella alta preserved the patellar position and clinical outcomes for at least 3 years. Predisposing factors that may potentially affect postoperative clinical outcomes of the 3D transfer of tibial tuberosity include an increased BMI, valgus knee, limited ROM, and poor preoperative clinical outcomes.