Morphology and distribution characteristics of subchondral bone cysts in the talus based on CT three-dimensional reconstruction / 中华创伤杂志

ABSTRACT

Objective:To analyze the morphology and distribution characteristics of subchondral bone cysts of the talus by CT three-dimensional reconstruction.Methods:A total of 176 patients diagnosed with subchondral bone cyst of the talus after CT scan of the ankle or foot from 2015 to 2020 were retrieved from the imaging report database of Tianjin Hospital, including 77 males and 99 females, aged 14-84 years［(56.1±14.0)years］. After three-dimensional reconstruction of the talus and cyst area by Mimics 20.0 software, an equal 2×2 grid configuration was constructed to divide the domed articular surface into four regions anteromedial, anterolateral, posteromedial and posterolateral. For subchondral cyst of the talus, area involved under grid localization, gender, age and side of the onset were recorded. The anteroposterior diameter, transverse diameter, depth, surface area and volume of the subchondral bone cyst of the talus were measured.Results:Subchondral cyst of the talus was anteromedial in 131 patients (74.4%), anterolateral in 5(2.8%), posteromedial in 34(19.3%), and posterolateral in 6(3.4%). Subchondral cyst of the talus occurred in the older aged (≥60 years) for 78 patients (44.3%), in the middle aged (45-59 years) for 62(35.2%), in young adults for 32(18.2%), and in preadolescents for 4(2.3%). The age composition of the subchondral cyst of the talus involving the anteromedial, anterolateral, posteromedial and posterolateral regions was 59(49, 64)years, 44(39, 45)years, 61(54, 68)years and 40(22, 58) years, respectively (all P<0.01). There were no statistically significant differences in gender and side of the onset (all P>0.05). The anteroposterior diameter of the subchondral bone cysts located anteromedially, anterolaterally, posteromedially and posterolaterally was (9.7±4.4)mm, (3.5±1.1)mm, (10.3±4.4)mm and (2.1±0.8)mm, respectively; the transverse diameter was (5.4±1.7)mm, (3.9±1.8)mm, (5.9±2.2)mm and (3.4±1.1)mm, respectively; the depth was (7.1±2.4)mm, (3.2±2.2)mm, (8.2±3.0)mm and (3.9±1.9)mm, respectively; the surface area was 156.1(82.6, 198.2)mm 2, 23.0(21.4, 28.9)mm 2, 180.0(75.1, 230.4)mm 2 and 28.0(20.3, 36.7)mm 2, respectively; the volume was 77.1(37.1, 129.1)mm 3, 23.9(14.2, 37.8)mm 3, 104.6(37.7, 157.4)mm 3 and 13.0(10.4, 16.0)mm 3, respectively. When comparing the anteroposterior diameter, transverse diameter, depth, surface area and volume of the subchondral bone cysts in the anteromedial and posteromedial regions with the anterolateral and posterolateral regions, the differences were statistically significant (all P<0.01) except for the transverse diameter of the subchondral bone cysts in the anteromedial region and the anterolateral region ( P>0.05). In addition, the depth of subchondral bone cysts in the anteromedial region was significantly greater than that in the posteromedial region ( P<0.05). Conclusions:Subchondral bone cysts of the talar are commonly found in the middle- and old-aged population. Anteromedial lesions of the talar dome are the most commonly seen, with large and deeply involved cysts, followed by posteromedial lesions of the dome, while anterolateral and posterolateral lesions of the dome are less common and have smaller cyst sizes. An equal 2×2 grid configuration for talar cysts is useful in positioning and characterizing bone cysts, and can assist clinicians in accurately diagnosing and treating bone cysts.