ABSTRACT
Objective To find a new method of tangential view of patello femoral joint. Methods 62 cases of lateral knee radiographs were studied. The knee flexion angles, patello femoral angles, patello tibial angles and frontal patello tibial angles were measured and their relationships analyzed. The knee flexion angles and the patello femoral angles had linear relationship with a linear equation = 2 + 0.8x . The angles of posterior patellar line with tibial long axis and frontal tibial line were 3.3? and 12.7?respectively. According to the measurement results, an accessary positoning table was designed. The patients′ patello femoral joints were examined with the knee flexed at an angle of 30?. The patients were in supine position and the central X ray was angled at 73?vertically toward the film. Results 58 patello femoral joints of 40 patients were radiographically studied (10 males, 30 females) .All radiographs were classified into 4 degrees as Grade A, B, C and D. Eighteen cases were Grade A (31%), 30 cases were Grade B(52%), 8 cases were Grade C(18%)and 2 Grade D(3%).The reason for Grade D was due to small or negtive anterior patellotibial angles. Conclusion This new method of tangential view of patello femoral joint is accurate, comfortable and simple and could be used as routine examination for patello femoral joint diseases.