Value Of TT-TG Distance On Diagnosis Of Recurrent Patellar Instability

Objective When diagnosed patellar instability, doctors often need to analyze both medical history and imaging findings, because of the lack of characteristic signs. In recently, a lot of domestic and international researches have shown that tibial tuberosity-trochlear groove distance is greater in patients diagnosed with patellar instability than healthy people. And they also find that TT-TG has a correlation between patellofemoral disorder. This study aimed to evaluate the value of TT-TG distance in recurrent patellar instability.Methods We chose patients whose first diagnose was recurrent patellar instability from January 2010 to December 2013 in the first affiated hospital of Anhui Medical University. Through telephone follow-up and subsequent visit, we located our subjects. All subjects underwent bilateral long leg computed tomography scan to determine TT-TG distance. TT-TG in symptomatic and asymptomatic knees in the same individual was compared statistically. We also analyzed their medical history, mechanism of injury, and distribute of symptomatic knees.Ruslts Thirty-four patients was involved in this study(7 male,27 female, aged between 14 to 31). Mean TT-TG distance in the smptomatic knee was (16.47±3.87) mm, compared to (15.61±3.52) mm in the asymptomatic knee. There was no significant difference between the two mean values(P>0.05). The number of symptomatic knee which appeared to be right was 21, when it came to left, it showed to be 13. And as many as 53 percent patients said that their first dislocation of patellar was caused by direct injury.Conclusion TT-TG distance is a high risk of patellar instability. But it shows no significant different between symptomatic knee and asymptomatic knee in unilateral recurrent patellar instability. Moreover, the asymptomatic knee has a trend to develop unstable, and the tendency would be more obvious as time goes on.