Anatomical Components Associated With Increased Tibial Tuberosity–Trochlear Groove Distance

Abstract

Background: Increased tibial tuberosity–trochlear groove (TT-TG) distance is an important indicator of medial tibial tubercle transfer in the surgical management of lateral patellar dislocation (LPD). Changes to TT-TG distance are determined by a combination of several anatomical factors. Purpose: To (1) determine the anatomical components related to increased TT-TG distance and (2) quantify the contribution of each to identify the most prominent component. Study Design: Case-control study; Level of evidence, 3. Methods: Included were 80 patients with recurrent LPD and 80 age- and body mass index–matched controls. The 2 groups were compared in TT-TG distance and its related anatomical components: tibial tubercle lateralization (TTL), trochlear groove medialization, femoral anteversion, tibiofemoral rotation (TFR), tibial torsion, and mechanical axis deviation (MAD). The Pearson correlation coefficient ( r) was calculated to evaluate the association between increased TT-TG distance and its anatomical parameters, and factors that met the inclusion criteria of P < .05 and r ≥ 0.30 were analyzed via stepwise multivariable linear regression analysis to predict TT-TG distance. Results: The LPD and control groups differed significantly in TT-TG distance, TTL, TFR, and MAD ( P < .001 for all). Increased TT-TG distance was significantly positively correlated with TTL ( r = 0.376; P < .001), femoral anteversion ( r = 0.166; P = .036), TFR ( r = 0.574; P < .001), and MAD ( r = 0.415; P < .001), and it was signficantly negatively correlated with trochlear groove medialization ( r = −0.178; P = .024). The stepwise multivariable analysis revealed that higher TTL, excessive knee external rotation, and excessive knee valgus were statistically significant predictors of greater TT-TG distance ( P < .001 for all). The standardized estimates that were used for evaluating the predictive values were larger for TFR compared with those for TTL and MAD. Conclusion: TTL, TFR, and MAD were the main independent anatomical components associated with increased TT-TG distance, with the most prominent component being TFR. The association of TT-TG distance to each component analyzed in our study may help guide surgical planning.