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.