Gait Inefficiency in Spina Bifida

Normal walking mechanisms are designed to reduce the excursion of the centre of mass in all three anatomic planes and so to reduce the energy expenditure. Children with low lumbar level spina bifida walk with a gross lateral sway, with flexed hips and knees and with marked pelvic rotation. This is very energy consuming. It was shown by Duffy et al (1996) that it is the lateral trunk sway (compensating for the weak hip abductors) that has the most influence on the raised oxygen cost. There is a positive correlation between increasing pelvic obliquity, pelvic rotation and hip ab/adduction and oxygen cost. It was shown that a posterolateral psoas transfer cannot reduce the oxygen cost of walking.

Bare et al looked at the kinematics of children with spina bifida and concluded that pelvic obliquity was the abnormality that correlated most closely with increased energy consumption and inferred that failure of the abductors to control the centre of mass displacements was the prime cause of energy inefficiency in these individuals. The increased pelvic rotational range seen did not seem to lead to an increase in energy consumption. They were not able to demonstrate significant deviations from normal in the centre of mass displacements compared with normals however they only examined 14 spina bifida patients.

Alman et al retrospectively examined 52 children with L3 and L4 lesions to assess whether dislocated hips were best left dislocated or reduced. Theoretically, a reduced hip would be able to generate better coronal plane truncal control than one without an effective fulcrum but the differences were not significant and the cases where surgery failed were worse than not operating at all. A successful operation led to a superior gait efficiency but the 20% of reduced hips that subluxed or dislocated subsequently fared worse than the untreated ones. A subgroup of 12 patients with L4 as their lowest functioning level had oxygen costs performed with the successfully operated group having a cost of .27 ml/Kg/M compared with the unoperated group with a cost of .36 ml/Kg/M.

Another cause of inefficient gait is the failure of the ankle dorsiflexion knee extension couple resulting from external tibial torsion as shown by Vankoski et al. The failure of lever arms at the hip and the foot are common with patients suffering from cerebral palsy.

It is the practice of many centres to encourage all children with spina bifida to walk. The single greatest predictive factor of long-term ambulation is the neurological level of the lesion. Children with high lesions will go off their feet, children with sacral lesions will continue to walk. There is however a big group in the middle and the question is what will happen to them.

Serial measurements in spina bifida patients have shown that in contrast with CP, with age the oxygen cost tends to drop to more normal levels in the early teenage years. A failure to do so puts them at risk of eventually stopping walking. This an important finding because it can guide treatment objectives (walking versus non walking).

Orthotic measures have been examined with respect to gait efficiency with benefits being shown from AFOs and more extensive devices. Although AFO use would be expected to have a beneficial effect on the sagittal kinematics and kinetics this is not seen in all the studies that have shown reduced energy consumption associated with AFO use (Duffy, 2000). The ultimate aid for efficient locomotion in high level children is the wheelchair (Williams, 1983).

References

Alman BA, Bhandari M, Wright JG. Function of dislocated hips in children with lower level spina bifida. J Bone Joint Surg Br 1996;78(2):294-8.

Bare A, Vankoski SJ, Dias L, Danduran M, Boas S. Independent ambulators with high sacral myelomeningocele: the relation between walking kinematics and energy consumption. Dev Med Child Neurol 2001;43(1):16-21.

Duffy CM, Hill AE, Cosgrove AP, Corry IS, Graham HK. The influence of abductor weakness on walking in spina bifida. Gait Posture 1996;4:34-38.

Beneficial effect of AFOs:

Duffy CM, Graham HK, Cosgrove AP. The influence of ankle-foot orthoses on gait and energy expenditure in spina bifida. J Pediatr Orthop 2000;20(3):356-61.

Stott NS, Zionts LE, Gronley JK, Perry J. Tibialis anterior transfer for calcaneal deformity: a postoperative gait analysis. J Pediatr Orthop 1996;16(6):792-8.

Galli M, Crivellini M, Fazzi E, Motta F. Energy consumption and gait analysis in children with myelomeningocele. Funct Neurol 15(3):171-5.

Thomas SE, Mazur JM, Child ME, Supan TJ. Quantitative evaluation of AFO use with myelomeningocele children. Z Kinderchir 1989;1(38):38-40.

Vankoski SJ, Michaud S, Dias L. External tibial torsion and the effectiveness of the solid ankle-foot orthoses. J Pediatr Orthop 2000;20(3):349-55.

Above knee orthotic use:

Cuddeford TJ, Freeling RP, Thomas SS, et al. Energy consumption in children with myelomeningocele: a comparison between reciprocating gait orthosis and hip-knee-ankle-foot orthosis ambulators. Dev Med Child Neurol 1997;39(4):239-42.

Lough LK, Nielsen DH. Ambulation of children with myelomeningocele: parapodium versus parapodium with Orlau swivel modification. Dev Med Child Neurol 1986;28(4):489-97.

Katz DE, Haideri N, Song K, Wyrick P. Comparative study of conventional hip-knee-ankle-foot orthoses versus reciprocating-gait orthoses for children with high-level paraparesis. J Pediatr Orthop 1997;17(3):377-86.

Guidera KJ, Smith S, Raney E, et al. Use of the reciprocating gait orthosis in myelodysplasia. J Pediatr Orthop 1993;13(3):341-8.

Merkel KD, Miller NE, Merritt JL. Energy expenditure in patients with low-, mid-, or high-thoracic paraplegia using Scott-Craig knee-ankle-foot orthoses. Mayo Clin Proc 1985;60(3):165-8.

Wheelchair use:

Williams LO, Anderson AD, Campbell J, Thomas L, Feiwell E, Walker JM. Energy cost of walking and of wheelchair propulsion by children with myelodysplasia: comparison with normal children. Dev Med Child Neurol 1983;25(5):617-24.