Background: External tibial torsion (ETT) is a common bony deformity in children with cerebral palsy (CP). The current recommended treatment is tibial derotation osteotomy (TDO) to improve gait biomechanics. Satisfactory short-term results after TDO have been reported but long-term results have not been studied. The purpose of this study was to evaluate the long-term outcome following TDO to correct ETT in ambulatory children with CP.
Methods: Following IRB approval, gait kinematics and passive range of motion measurements were retrospectively evaluated in children with spastic CP who underwent TDO due to ETT comparing preoperative (E0), short-term postoperative (E1; 1 to 3 y post), and long-term postoperative (E2; >5 y post) results. Limbs were categorized as corrected, undercorrected, or overcorrected at both E1 and E2, by comparing mean tibial rotation (MTR) in gait to a group of typically developing children. Age at surgery, E0 MTR, E0 gait velocity, gross motor function classification system (GMFCS) score, and foot deformity were evaluated to determine their influence on long-term results.
Results: The study sample consisted of 43 legs (with E0 and E2) and 22 legs (with E0, E1, and E2). The mean age at surgery was 10.3±3.4 years (range, 6 to 19.2 y). In the group MTR trended toward improvement moving from -26±17 degrees (E0, external negative) to -16±16 degrees (E1) and relapsed to -23±17 degrees at the long term (P=0.071, E0/E1; P=0.589, E0/E2). Improvement was also seen in the transmalleolar axis (P=0.074), mean ankle rotation, and mean foot orientation (P<0.05, E0/E2). At the long-term evaluation, 16 legs (37%) were found to be in the kinematic corrected group, 25 legs (58%) in the kinematic undercorrected group, and 2 legs (5%) in the kinematic overcorrected group. There were no significant differences between the corrected and undercorrected groups of children with respect to age at surgery, GMFCS, E0 MTR, gait velocity, or foot deformity.
Conclusions: Although internal TDO improves ETT in the short term, recurrence is frequent with an apparent developmental trend toward external rotation of the tibia.
Levels of evidence: Level IV-therapeutic study.