Differences in lateral ankle ligaments between affected and unaffected legs in children with spastic hemiplegic cerebral palsy.

OBJECTIVES

To investigate the architectural alterations of the lateral ankle ligaments in spastic hemiplegic cerebral palsy.

METHODS

Eight children (5 male and 3 female; mean age ± SD, 5.2 ± 2.7 years) with spastic hemiplegic cerebral palsy were recruited. A modified Ashworth scale and passive ankle dorsiflexion angle were evaluated. Sonograms of the anterior talofibular ligament and calcaneofibular ligament were obtained to measure ligament thickness, and the anterior talofibular/calcaneofibular ligament thickness ratio was calculated. Two sonographic measurements were taken to check for intra-rater reliability.

RESULTS

The interclass correlation coefficients of the repeated anterior talofibular ligament and calcaneofibular ligament thickness measurements in the unaffected/affected legs were 0.960/0.945 and 0.922/0.933, respectively. The anterior talofibular ligament thickness in the affected legs was significantly greater than that in the unaffected legs (2.50 ± 0.35 versus 1.40 ± 0.28 mm; P = .011), but the calcaneofibular ligament thickness in the affected legs was significantly less than that in the unaffected legs (0.80 ± 0.18 versus 1.28 ± 0.31 mm; P = .021). The anterior talofibular/calcaneofibular ligament thickness ratio in the affected legs was significantly greater than that in unaffected legs (2.10 ± 0.81 versus 1.03 ± 0.13; P = .012). The ratio was positively correlated with the modified Ashworth scale and age but negatively correlated with the passive ankle dorsiflexion angle in the affected legs.

CONCLUSIONS

This study revealed an increased anterior talofibular ligament thickness and a decreased calcaneofibular ligament thickness in the affected legs compared with the unaffected legs. These architectural features of the lateral ankle ligaments may contribute to the equinovarus deformity of the ankle together with spastic leg muscles in children with spastic hemiplegic cerebral palsy.