The Research Of Patellofemoral Alignment By Dynamic CT

Objective:(l).The purpose of this study was to evaluate the reproducibility of the parameters (seven parameters) which have been described for the additional measurement of patellofemoral alignment on CT scan.(2). The purpose of this study was to evaluate the patellar motion as knee flection by dynamic CT in patients with anterior knee pain syndrome.Material and methods:(1). Fifteen patients (30 knees) ,with anterior knee pain syndrome were randomly selectedfor this study. At each knee position in 0 and 30 of flexion, axial CT image of thepatellofemoral joints was obtained on the condition of the thigh muscle relaxation. The seven parameters were measured by additional and single means. For statistical analyses, we studied the reproducibility by means of the intraclass correlation coefficient (ICC). (2). Twenty-five patients (33 knees) ,with anterior knee pain syndrome participated in thestudy. The patellofemoral joints were examined with the knee in 0 ,15 ,30 and 40of flexion. At each knee position, kinematic axial CT image was obtained on the condition of the thigh muscle relaxation and contraction. Fifty healthy volunteers (30 knees) with no history of previous or current knee problems also underwent CT scanning following the same procedure. Three angles were measured: patellar tilt angle (PTA), femoral trochlear angle (FTA), and congruence angle (CA). For statistical analyses, we used the Wilcoxon matched test and the Mann-Whitney U-test.Results:(1). In the knee at 0 and 30 of flexion. The parameters of PTA and LPA by both means of additional and single, the CA and the FTA by means of additional showedexcellent reliability (ICC>90%). The parameters of CA showed excellent reliability (ICC>90%) by means of single. The LS by the two ways, the FTA and the FTD by single showed poor correlation (ICC<75%). The others parameters showed moderate correlation (ICC>75%).(2). In 30 of flexion to extension, contraction of the thigh muscle increased CA anddecrease the PTA (p<0.05) in symptomatic knees (quantitative). In the same way contraction of the muscles caused shift and tilt of the patella in symptomatic knees (qualitative). The most frequently observed was tilt and lateralisation. With the contraction of the muscle, among the twelve symptomatic knees which were normal when their musclewere relaxing, four had lateral tilt or shift in 30 of flexion. With the contraction of the muscle, six of the remained eight normal knee were found potential abnormity at the patella position in 15 of flexion to extension.Conclusion:(1). In our conclusion, the parameters of PTA LPA CA FTA showed excellent reliability bythe means of CT additional scan. Especially for evaluating the dynamic patellar motion,the parameters of CA and FTA were better by the means of additional than by the means ofsingle.(2). In our opinion, By the additional dynamic CT the qualitative and quantitativeevaluation of the imaging in the first 30 of flexion with thigh muscle contraction is necessary for a correct diagnosis.