The Dynamic CT Measurement Of Patellar Tracking With Patellofemoral Pain Syndrome

ObjectiveThe purpose of this study was to investigated the dynamic patellar tracking patterns in symptomatic patients with patellofemoral pain syndrome by using 320-row dynamic volume computerized tomography during knee flexion. We also tested whether there is correlation between patellar tracking and patellofemoral indices in patients with patellofemoral pain syndrome. We hope these data may provide useful information for diagnosis and treatment in patellofemoral pain syndrome.MethodFrom Mar 2010 to Feb 2011, twenty-four female patients with patellofemoral pain syndrome in Jinan Military General Hospital were recruited in this study as experimental group by chance, in which eight patients have bilateral symptomatic knees. Their average age were 31.1 years (ranging from 18 to 46), there were thirty-two symptomatic knees in experimental group. Thirteen healthy female volunteers were recruited in this study as control group randomly, with an average age of 32.1years (ranging from 19 to 45). There were twenty-six asymptomatic knees in control group. Thirty-two symptomatic knees of experimental group and twenty-six asymptomatic knees of control group were examined with 320-row dynamic volume computerized tomography scan at every 15°from 0°to 120°during knee flexion with quadriceps isometric contraction. Three-dimensional knee images were reconstructed by using Vitrea 2.1 software. Coordinate systems based on anatomical landmarks were established and the parameters including patellofemoral indices (patellar trochlea angle, lateral patellar tilt angle, lateral patellar displacement) and patellar tracking parameters (patellar tilt, patellar shift, patellar rotation) were measured in detail. Each variable was described by its mean and standard deviation at each target flexion angle, All the results were analyzed by using two group t-test and correlation analysis, with a probability less than 0.05 regarded as significant. Result1,There is significant difference in patellar tracking and patellofemoral indices between case and control group. During 15°～45°knee flexion, there is significant difference in patellar shift between two groups (P<0.001). Significant difference in patellar rotation between two groups occurred during 15°～120°knee flexion (P<0.001). There is significant difference in patellar tilt between two groups during 15°～45°knee flexion (P<0.001). During 15°～45°knee flexion, there is significant difference in patellar trochlea angle between two groups (P<0.05). During 15°～60°knee flexion, significant difference in lateral patellar tilt angle between two groups exited (P<0.001). There is significant difference in lateral patellar displacement between two groups during 15°～60°knee flexion (P<0.001).2,We observed linear correlation between patellar tracking and patellofemoral indices. In control group, there is positive linear correlation between patellar tilt and patellar trochlea angle (r=0.7863,P<0.05, R2=0.6183); between patellar tilt and lateral patellar displacement (r=0.8432,P<0.01, R2=0.7110); between patellar rotation and lateral patellar tilt angle (r=0.7924,P<0.05, R2=0.6279); between patellar shift and lateral patellar displacement (r=0.9071,P<0.001, R2=0.8228). In case group there is positive linear correlation between patellar tilt and lateral patellar displacement (r=0.7072,P<0.05, R2=0.5001) and between patellar shift and lateral patellar displacement (r=0.7333,P<0.05, R2=0.5377). There is negtive linear correlation between patellar rotation and patellar trochlea angle (r=-0.7414,P<0.05, R2=0.5497) and between patellar rotation and lateral patellar tilt angle (r=-0.7815,P<0.05, R2=0.6107).Conclusion1,There is significant difference in patellar tracking and patellofemoral geometric modality between patients with patellofemoral pain syndrome and healthy subject.2,There is linear correlation between patellar tracking and patellofemoral geometric modality.3,Patellar tracking is under the control of patellofemoral geometric modality and soft tissue around patella during 15°～45°knee flexion, but it only restricted by the patellofemoral geometric modality during deep knee flexion.4,During 15°～45°knee flexion, the patellar tracking of patellofemoral pain syndrome contribute to clinical diagnosis and trement.