CT DETERMINATION OF TIBIAL TUBERCLE LATERALIZATION IN PATIENTS PRESENTING WITH ANTERIOR KNEE PAIN

Anterior knee pain is commonly associated with patellofemoral malalign ment. Both conventional radiographic measurements and CT measurements have been proposed to define and confirm the sometimes difficult clini cal diagnosis of anterior knee pain secondary to patellofemoral malali gnment. Using CT imaging with computerized technique to measure anatom ic relationships, we evaluated patients (n=50) with anterior knee pain for excessive lateralization of the tibial tubercle. The symptomatic knee of each patient was compared with their asymptomatic knee as well as with the knees of patients with other causes of anterior knee pain (n=10) and with the knees of asymptomatic controls (n=10), The sympto matic knee of patients with suspected patellofemoral malalignment demo nstrated significantly greater lateralization of the tibial tubercle ( 12.2 +/- 0.5 mm) than did the asymptomatic knee (9.0 +/- 0.7 mm). The symptomatic knees of patients with patellofemoral malalignment also de monstrated significantly greater lateralization of the tibial tubercle than did the knees of patients with other causes of anterior knee pai n (5.9 +/- 0.9 mm). When a control population was added to the analysi s, the patients with symptomatic patellofemoral malalignment demonstra ted significantly greater lateralization of the tibial tubercle than d id the controls (6.4 +/- 0.4 mm). Using a critical value of 9 mm later alization, the CT diagnosis of patellofemoral malalignment had a speci ficity of 95% and a sensitivity of 85%. We conclude that CT determinat ion of tibial tubercle position assists the diagnosis of patellofemora l malalignment.