Comparison of tibial tubercle-Roman arch distance and tibial tubercle-trochlear groove distance in patients with patellar dislocation or subluxation.

Objective: To compare tibial tubercle-trochlear groove (TT-TG) and tibial tubercle-Roman arch (TT-RA) distances in patients with patellar dislocation or subluxation, evaluate TT-RA reliability and reproducibility, and determine pathological threshold values for surgical treatment using magnetic resonance imaging (MRI) and computed tomography (CT).

Materials And Methods: Retrospective analysis included 259 patient and 262 control examinations of knee MRIs and/or CTs performed. TT-RA, TT-TG, and tibial tubercle-posterior cruciate ligament (TT-PCL) distances, Roman Arch height, trochlear sulcus angle, and total femoral condyle width were measured by two radiologists, and trochlear morphology was assessed. Measurements were compared using the Student's t-test. Reliability and reproducibility were evaluated using intraclass correlation coefficients (ICC). Receiver Operating Characteristic (ROC) analysis determined pathological thresholds, and Pearson correlation compared TT-TG and TT-RA.

Results: TT-RA, TT-TG, TT-PCL distances, and trochlear sulcus angles were significantly different between patient and control groups (p < 0.001). Subgroup analyses for MRI and CT also showed significant differences (p < 0.001). TT-RA distance had higher ICC values for reproducibility and reliability (> 0.959; > 0.988). ROC analysis determined MRI thresholds as TT-RA > 17.30 mm, TT-TG > 13.30 mm, TT-PCL > 23.8 mm, and trochlear sulcus angle > 146°; for CT, TT-RA > 18.80 mm, TT-TG > 15.60 mm, TT-PCL > 21.5 mm, and trochlear sulcus angle > 148°. Strong correlation was found between TT-TG and TT-RA distances (r = 0.867, p < 0.001).

Conclusion: TT-RA distance is a reliable and reproducible method for tibial tubercle localization and shows higher reliability than TT-TG. Thresholds of 17.3 mm (MRI) and 18.8 mm (CT) for TT-RA can guide surgical indications.

Key Points: Question The reliable measurement of the tibial tubercle lateralization is crucial for planning the treatment of patients with patellar dislocation/subluxation. Findings The tibial tubercle-Roman arch (TT-RA) distance is more reliable and repeatable than the tibial tubercle-trochlear groove (TT-TG) distance in patients with patellar dislocation and subluxation. Clinical relevance TT-RA distance can be used in clinical practice as an alternative to tibial tubercle-trochlear groove (TT-TG) distance for surgical treatment indications in patients with patellar subluxation and dislocation.