Computed tomography-based pathogenic investigation of patellar dislocation

Purpose: To compare various values in computed tomography (CT) scanning between patella dislocation patients and health controls, to define the difference between the two groups, and to determine the rate of patellofemoral anatomical deformities in patients, providing relevant evidence for the appropriate treatment. Method: 100 health controls and 100 patients with patella dislocation from 2005 to 2014 were retrospectively analyzed through CT scanning. 6 values, including lateral patellofemoral angle, patella inclination angle, congruence angle, sulcus angle, trochlear groove depth, and tibial tuberosity-trochlear groove distance, were measured to identify the differences between controls and patients. Result: All of the six values were found to be significantly different between the 2 groups (P<0.05), lateral patellofemoral angle (-12.73±17.77 vs. 7.82±5.34), patella inclination angle (22.93±11.34 vs. 8.67±3.56), congruence angle (40.24±26.24 vs. 5.25±20.68), sulcus angle (155.85±11.39 vs. 140.22±5.49), trochlear groove depth, and TT-TG (19.84±6.27 vs. 14.12±4.00). And there were 88.75% patients with trochlear dysplasia, 52.04% patients’ TT-TG distance was greater than or equal to 20 mm. Conclusion: Majority of patella dislocation patients were affected by patellofemoral anatomical deformities, so for patients, especially for children and young adolescent patients, conservative treatment could not remove the causation of dislocation and prevent redislocation obviously, early detection and diagnosis should to be advocated, and more aggressive etiotropic treatments based on patients’ pathogenetic condition should be performed to prevent redislocation and sequelae.