Variation Of Transverse Ligament Tubercles With Different Age And Gender On Multi-slice Spiral Computed Tomography

Objective To retrospectively analyze the density of atlas transverse ligament tubercles on MSCT and measure the height of the transverse ligament tubercles, to evaluate the correlation of the density and height with respect to age, gender and side-to-side differences, and the density and height variation of tubercles with growing age, then analyze the influencing factors of the tubercles.Methods A consecutive series of 339 cervical MSCT images were randomly selected from 1 January,2013 to 31 May,2014, these patients underwent a cervical or sinus MSCT at Shandong Medical Imaging Research Institute. These patients had been referred for a variety of reasons, such as head and neck discomfort, dizziness, upper extremity numbness, head and neck tumor, suspected cervical disease or sinusitis, and so on. These patients which bilateral or unilateral atlas transverse ligament tubercles could not be measured because of trauma, tumors, congenital malformation, scanning technology and other factors were excluded.170 men (50.1%) and 169 women (49.9%) were included in this study with mean age 33.3±21.6 years (range,1 month to 83 years) and 38.9±23.8 years (range,4 months to 82 years), respectively. All the patients were divided into 8 groups by age:0 to 9 years was the first group (n=56),10 to 19 years was the second group (n=58),20 to 29 years was the third group (n=37), 30 to 39 years was the fourth group (n=34),40 to 49 years was the fifth group (n=42), 50 to 59 years was the sixth group (n=39),60 to 69 years was the seventh group (n=40), above 70 years was the eighth group (n=33). Each patient was observed whether there were transverse ligament tubercles on medial surface of atlas lateral mass, and then the density and shape of atlas transverse ligament tubercles were observed. The density of transverse ligament tubercles was divided into the following four types according to whether the tubercles were visible and the density of transverse ligament tubercles. Type 0, there was no transverse ligament tubercle; type Ⅰ, transverse ligament tubercle was equal density, while the surface of bone cortex was high density; type Ⅱ, transverse ligament tubercle was mixed density or slightly higher density; type Ⅲ, almost the whole transverse ligament tubercle was high density. The bony anatomy of the atlas was displayed symmetrically by aligning the axial plane and the height of bilateral transverse ligament tubercle was measured three times for each patient, the average values were calculated and recorded. Paired samples T-test, independent samples T-test, multiple analyses of covariance, Fisher’s exact test and other statistical methods were used to statistical description and analysis. The type of density and the average height of each age group were calculated respectively, The density and the height of the transverse ligament tubercles were correlated with age, gender and side-to-side differences were analyzed by using statistical software. Finally, the inter-observer performance was assessed.Results Neither of the transverse ligament tubercles were visible in 54 (15.9%, 54/339) cases, a unilateral tubercle were observed in 3 cases (0.9%,3/339), and bilateral tubercles were seen in 282 cases (83.2%,282/339).The density type of the first group were mostly type 0, followed by type Ⅰ, type Ⅱ and type Ⅲ were rare; The density type of the second group were mostly type Ⅰ and type Ⅱ, type Ⅲ were rare; The density type of the third group were mostly type Ⅱ; The density type of the fourth to eighth group were mostly type Ⅱ and type Ⅲ, type 0 and type I were rare. There were no significant difference between men and women (F=0.022, p=0.882), as well as left side and right side (F=1.086, p=0.319). There was a close correlation between the age and the density type of the transverse ligament tubercles (χ2= 637.7, p=0.000).The average height of the left and right transverse ligament tubercles were 2.76±1.54 mm and 2.78±1.51 mm, respectively, with no significant side to side differences (t=0.769, p=0.442).The average height of the transverse ligament tubercles in men and women were 2.70±1.61 mm and 2.84±1.43 mm, respectively, with no significant gender differences (t=1.220,p=0.223).The average height of the left atlas transverse ligament tubercles in men and women were 2.71±1.62 mm and 2.81±1.45 mm, respectively, the average height of the right atlas transverse ligament tubercles in men and women were 2.70±1.61 mm and 2.87±1.41 mm respectively, with no significant gender differences (men:t=0.217, p=0.829, women:t=1.448, p=0.150), and no significant side to side differences (left: t=0.655, p=0.513, right:t=0.976, p=0.330).The average height of left and right transverse ligament tubercles on 0 to 9 years were 0.42±0.87 mm and 0.42±0.92 mm, respectively; The average height of left and right transverse ligament tubercles on 10 to 19 years were 2.21±0.97 mm and 2.23±1.18 mm, respectively; The average height of left and right transverse ligament tubercles on 20 to 29 years were 2.71±0.97 mm and 2.80±0.93 mm, respectively; The average height of left and right transverse ligament tubercles on 30 to 39 years were 3.09±0.76 mm and 3.13±0.69 mm, respectively; The average height of left and right transverse ligament tubercles on 40 to 49 years were 3.30±1.00 mm and 3.36±1.00 mm, respectively; The average height of left and right transverse ligament tubercles on 50 to 59 years were 3.60±0.87 mm and 3.68±0.65 mm, respectively; The average height of left and right transverse ligament tubercles on 60 to 69 years were 3.98±0.70 mm and 3.92±0.64 mm, respectively; The average height of left and right transverse ligament tubercles on above 70 years were 4.24±1.29 mm and 4.19±1.01 mm, respectively. The height of the transverse ligament tubercles increased linearly with age (left:r=0.723, p=0.000, right:r=0.744, p=0.000).Conclusion The transverse ligament tubercle is a bony prominence on the medial aspect of lateral mass of the atlas where the transverse ligament attaches. The tubercle is equal density and the surface of tubercle is high density, as people grow older, the density of tubercle gradually increases, and finally shows almost high density. The density of the transverse ligament tubercle on MSCT linearly increases with increasing age, and it is not affected by gender and laterality. The transverse ligament tubercle grows from nothing to something, from small to large, the height of the transverse ligament tubercle on MSCT linearly increases with increasing age, and it is not affected by gender and laterality.