Ankle alignment after tibial lengthening and syndesmotic fixation: A comparison study

Background: This study aimed to compare two techniques of syndesmotic fixation in terms of preventing lateral malleolus migration and ankle malalignment during tibial lengthening. Methods: Children who had tibial lengthening > 20 mm using Taylor Spatial Frame were included. Two techniques of syndesmotic fixation were evaluated: Transverse tricortical screws and oblique quadricortical screws. Radiographs, before frame application and at frame removal, were reviewed. Tibial length, angular deformity, distal tibiofibular index (DTFI), proximal tibiofibular index (PTFI), and lateral distal tibial angle (LDTA) were measured. Malhotra grades and duration of external fixation were also recorded. Eighteen patients (21 limbs) were identified (transverse screws in 15 limbs and oblique screws in 6 limbs). Age and gender were similar for both groups. There was no significant difference in lengthening amount (transverse: 40 mm and oblique: 35 mm), angular correction, lateral malleolar and fibular head migration, LDTA change, and frame duration. Results: After lengthening, and only in the transverse group, DTFI and PTFI changed significantly (DTFI pre: 12 mm, post: 8 mm, P = 0.01; PTFI pre: 17 mm, post: 22 mm, P = 0.02). Two ankles in the transverse group moved from Malhotra 0 to 1; however, no grade change was noted in the oblique group. No screw-related complications were encountered in either group. Conclusion: Although migration of lateral malleolus was encountered in the transverse group, the amount of DTFI change was similar to the oblique group and no LDTA change was noted in either group. No advantage of one syndesmotic fixation method over the other was found in this study.