Radiographical verification for clinical representativeness of femoral component of quadriceps angles as quadriceps femoris

10.6492/FJMD.202208_13(3).0002

Chen-Heng Hsu；Chi-Chuan Wu；Yi-Hsun Yu；Po-Cheng Lee；Ying-Chao Chou；Yung-Heng Hsu；Wen-Ling Yeh

patellar malalignment ； pelvic width ； Q-angle ； representativeness

Formosan Journal of Musculoskeletal Disorders

13卷3期（2022 / 08 / 01）

116 - 123

英文

Background: A quadriceps angle (Q-angle) had been supported to affect the patellar tracking by lateral traction forces. However, whether the femoral component of the Q-angle can represent the action of the quadriceps femoris has not yet been confirmed in the literature. Purpose: The aim of this retrospective study intended to use plain radiography to verify whether the femoral component of a Q-angle can represent the action of the quadriceps femoris. Methods: Between May 2013 and July 2017, 100 consecutive young adult patients (50 men and 50 women, aged 34 ± 5 and 33 ± 6 years, respectively) who sustained chronic unilateral lower extremity injuries (unilateral femoral or tibial nonunions or malunions) were studied. The pelvis and contralateral lower extremity were intact at the time of injury. The evaluation was for the contralateral intact lower extremity, and the injured lower extremity was not involved. The full-length standing scanogram was used to evaluate the pelvic width (PW), femoral head distance (HD), contralateral femoral length (FL) without injury, rectus Q-angle (R-Q angle), vastus Q-angle (V-Q angle), and clinical Q-angle (C-Q angle; i.e., Q-angle). Results: FL was statistically different between sexes (average, 44.5 cm in men and 40.6 cm in women; p < 0.001). Other parameters (PW, HD, R-Q angle, V-Q angle, and C-Q angle) were not statistically different (p > 0.05). PW/FL ratio was statistically different between sexes (average, 0.63 in men and 0.69 in women; p < 0.001). High correlation occurred among C-Q angle, R-Q angle, and V-Q angle (correlation coefficient of 0.738 to 0.931). The simple linear regression revealed of (C-Q angle) = 0.91 (R-Q angle) + 3.56° or (C-Q angle) = 0.93 (V-Q angle) + 0.38° in 100 patients. The multiple linear regression revealed of (C-Q angle) = 0.72 (R-Q angle) (p < 0.001) + 0.21 (V-Q angle) (p = 0.009) + 2.61°. Conclusion: The femoral component of a Q-angle may be used to represent the action of the quadriceps femoris. A shorter FL in women as compared to men may misidentify a wider PW visually.