Correlation between tibial tubercle-trochlear groove and 3D shift_{active extension} in patellar dislocation: An active...

To investigate the correlation between 3D shift_{active extension} (lateral patellar shift in active extension position based on newly established 3D measurement method) and static tibial tubercle-trochlear groove (TT-TG) distance in full knee extension with muscle relaxation.

42 knees of 24 patients with recurrent patellar dislocation were included in the study group and 38 knees of 30 subjects were included in the control group. TT-TG distance, bisect offset index_{muscle relaxation}, bisect offset index_{active extension} and 3D shift_{active extension} were measured to investigate the correlation between patellar lateral shift measurements and TT-TG distance.

In the recurrent patellar dislocation group, the correlation between TT-TG distance and 3D shift_{active extension} (r = 0.76 [95 % CI, 0.61 to 0.86]) was significantly higher than correlation between TT-TG distance and bisect offset index_{active extension} (r = 0.61 [95 % CI, 0.32 to 0.79]) and correlation between TT-TG distance and bisect offset index_{muscle relaxation} (r = 0.6 [95 % CI, 0.32 to 0.80]), with p = 0.01 and p = 0.03, respectively.

Significantly stronger correlation between TT-TG distance and 3D shift_{active extension} in patients with patellar dislocation was observed in this study. 3D shift_{active extension} could be considered as a preoperative evaluation for tibial tubercle osteotomy to both characterize the patellar lateral shift and estimate tibial tubercle lateralization to simplify the preoperative assessment procedures. The 3D shift_{active extension} obtained under muscle contraction conditions both simulated the functional state of the patellofemoral joint and improved the limitations of the 2D measurements, helping to improve surgical decision-making for functional rehabilitation.

Level III.