Imaging Anatomy Study And Clinical Significance Of Pronator Quadratus

BackgroundFracture due to trauma is very common in the clinic, especially the wrist. All the bones composed of the wrist are not only various in shape and different sizes, but also are very complex in anatomy. In the standard anteroposterior and lateral X-ray films, it’s difficult to find some occult fractures. As a result, getting misdiagnosis and delaying pathogenetic condition will cause adverse consequences. In the last century, the foreign scholars put forward the significant value of soft tissue indirect signs in the diagnosis of occult fracture, such as the scaphoid fat stripe and pronator quadratus sign and so on. However, no one mentioned it in china. Especially pronator quadratus sign is very important in the diagnosis of the fracture of radius and ulna end.ObjectiveTo investigate the morphological manifestation of pronator quadratus and clinical significance in standard lateral X-ray films and MRI images of normal wrists. It’s also to establish the range of normal values and the diagnosis standard of pronator quadratus in normal people. It is hoped to improve the diagnostic rate of occult fracture in wrist.MethodsThis study was conducted with285patients (Male,131; Female,154) who had wrist injured. These injured wrists were examined with standard X-ray films. Informed consent was obtained, and contralateral (symptomless) standard lateral X-ray films of normal wrists were obtained(Left,132; Right,153). The biggest thickness of pronator quadratus (BTPQ) was measured in the lateral radiograph, and to observe the morphological manifestation of normal pronator quadratus. Statistical analysis was performed to compare the difference of the thickness of pronator quadratus between male and female, and the difference of the morphology of pronator quadratus. Twenty volunteers were enrolled in the study, with MRI examination, and also to observe the morphological manifestation of pronator quadratus. Six cases had further examination with CT and MRI, because of the pronator quadratus swelling and pronated disability.ResultsThe mean thickness of BTPQ in the normal wrist was4.89±1.91mm, which in men was significantly larger than in women (P<0.01). The morphology of pronator quadratus was classified into four types:A, lamelliform; B, satiation; C, ambiguity in the inferior part; D, all ambiguity, which was correspondingly with MRI images. The difference of BTPQ was statistically significant (P<0.01) between men and women in A type, B type and C type respectively. Due to unclear, the D type can not be measured in the BTPQ. Overall, the difference of BTPQ (P<0.01) was statistically significant between A type and B type, and between A type and C type. The difference of BTPQ (P>0.05) were not statistically significant between B type and C type. BTPQ was7.69±2.61mm in the fracture group.ConclusionA type and B type were more than the other two types, and D type was the least. We can see that the fat in front of the pronator quadratus is clear in common. If BTPQ of men is more than6mm, and BTPQ of women is more than5mm, considering with clinic history and pronated disability, further examination should be considered to exclude occult fracture in the wrist.