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Varied TT-TG distance found during flexion of unstable knees
Among patients with symptomatic instability, researchers of this study found the mean tibial tuberosity–trochlear groove distance varied by 5.7 mm between 5° and 30° of flexion, indicating the impact of tibial tuberosity–trochlear groove distance in patellar tracking.
Researchers measured knee flexion angles and corresponding tibial tuberosity–trochlear groove (TT-TG) distances, bisect offset and patellar tilt among 51 symptomatic knees in 38 patients who underwent dynamic kinematic CT during a cycle of knee extension from flexion. For comparison, researchers interpolated results to standardized intervals between 5° and 30° of knee flexion and 37 knees had data for these intervals.
Andrew J. Cosgarea
Results showed a significant correlation between bisect offset and patellar tilt with TT-TG distance over all flexion angles. According to interpolated results, the mean tibial TT-TG distance of approximately 17.5±5.8 mm at 5° flexion decreased to approximately 15.5 mm at 10°. This figure changed to 13±5.5 mm at 20° and 11.5±4.9 mm at 30° flexion. Compared with 30° knee flexion, researchers found mean TT-TG distance was 1.5-times greater at 5° with 70.3% of knees showing a TT-TG distance of more than 15 mm vs. 24.3% of knees at 30°. – by Casey Tingle
Disclosures: Tanaka receives support from Toshiba America Medical Systems. Please see the full study for a list of all other authors’ relevant financial disclosures.