Correlation between plain radiographs and three-dimensional reconstruction on measurements of proportion of posteri- or malleolar fragments to tibial plafond

Abstract

Objective To investigate the correlation between plain radiographs and three-dimensional reconstruction on measurements of proportion of posterior malleolar fractures to tibial plafond. Methods From June 2013 to Dec. 2014, data of 27 patients with posterior malleolar fractures involving the tibial plafond who had undergone surgical treatment were retrospectively analyzed. There were 10 males and 17 females. The mean patient age was 48.9 years (range, 15-70 years). There were 14 cases of trimalleolar fracture, 11 of bimalleolar fracture and 2 cases with only posterior malleolar fracture. According to the Lauge-Hansen classification system, there were 22 cases of supination-external rotation, 1 of pronation-external rotation, 2 of pronation-abduction and 2 of unclassified type. According to the AO/OTA classification system, there were 22 cases of B, 3 of C and 2 of unclassified type. According to the Haraguchi classification system, there were 15 cases of type I and 12 of type II. There were 2 cases with the deep deltoid ligament disrupted and 3 cases with the inferior tibiofibular syndesmosis injury. The width of the posterior plafond fragment (PPF) and the remaining plafond fragment (RPF) were measured on the lateral plain radiograph. After 3D reconstruction was established, the area of the PPF and the RPF was measured. The width ratio of the PPF and the total plafond fragment (TPF) and the area ratio of the PPF and the TPF were calculated. Results The width ratio of the PPF and the TPF was 31.10% (range, 11.86%-52.24%), the area ratio of the PPF and the TPF was 20.13% (range, 5.86%-35.22%) and the correlation coefficient (r) between the width ratio of the PPF and the TPF and the area ratio of the PPF and the TPF was no statistically significant (r=0.350, P= 0.073). Concusion The width ratio of the PPF and the TPF could not represent the area ratio of the PPF and the TPF in the patients with the posterior malleolar fracture who's fracture line involved the plafond, and the ratio could be overrated in the lateral X-rays measurements. According to the plain radiographs, the evaluation of the proportion of posterior malleolar fragments to tibial plafond could not be as a reliable criterion for internal fixation of the posterior malleolar fragments. Key words: Ankle joint; Fractures bone; Imaging, three-dimensional