Magnetic Resonance Imaging Enables Precise Quantification of Patellar Height and Engagement in Patients Undergoing Tibial Tubercle Distalization Osteotomy for Objective Patellar Instability.
INTRODUCTION The objective of this study is to evaluate the improvements in patellar height and the amount of correction of Caton-Deschamps index (CDI), patellar height index (PHI), and sagittal patellofemoral engagement (SPE) after surgery of tibial tubercle osteotomy (TTO) and medial patellofemoral ligament (MPFL) reconstruction for objective patella instability (OPI) associated with patella alta. METHODS A consecutive series of TTO and MPFL reconstruction between 2021 and 2023 were prospectively enrolled. All patients underwent pre-operative and post-operatively (7 months) X-rays and Magnetic resonance imaging (MRI). Imageries were reviewed by three independent reviewers to measured CDI, PHI and SPE. RESULTS A total of 50 patients were enrolled in this study (mean age: 22.2 ± 7.2 years; 48% male). The mean tibial distalization was 6.7 mm ± 2.7. CDI decreased from 1.25 ± 0.2 to 0.97 ± 0.1 (p < 0.001). PHI improved from 1.28 ± 0.2 (mean ± SD) to 1.04 ± 0.19 (p < 0.001), and SPE from 31% ± 18.7 to 60% ± 13.5 (p < 0.001). CONCLUSION A standardized MRI protocol allows reproducible quantitative assessment of patellar height and sagittal patellofemoral engagement following distalization TTO. LEVEL OF EVIDENCE IV.