ObjectiveTo investigate the correlation between femoral distal medial torsion and patellofemoral joint malalignment and analyze the causes of patellofemoral joint disorders,which provide the new theory with clinical treatment.MethodsFrom May 2007 to June 2009,124 knees(95 cases) with patellofemoral joint disorders were enrolled in this study randomly.Each knee was scanned with CT in dynamic 20° -30° knee flax position.Femoral distal medial torsion angle (FMTA),patellar congruence angle (CA) and patellar tilt angle(PTA) were measured.The correlation between FMTA and CA or PTA was analyzed.Results FMTA ＜ 5° in 25 knees,≥5° in 99 knees,6 knees with trochlear dysplasia who were excluded.FMTA in 93 knees was 16.06° ± 5.68°,CA was 16.40° ± 5.48° and PTA was 19.59° ± 3.32°.The positive correlation was found between FMTA and CA when FMTA ＞ 10°through scatter diagram analysis (r =0.709,P ＜ 0.05 ).The positive correlation was found between FMTA and PTA when FMTA ＞10°( r =0.652,P ＜ 0.05),the positive trend declined when FMTA ＞ 27°.ConclusionsFemoral distal medial torsion is an important risk factor of patellofemoral joint malalignment.When FMTA ＞ 10°,FMTA and CA,PTA has positive correlation,but the positive tend between FMTA and PTA declines when FMTA ＞ 27°.