Elsevier

Gait & Posture

Volume 40, Issue 3, July 2014, Pages 391-398
Gait & Posture

Ankle-foot orthoses that restrict dorsiflexion improve walking in polio survivors with calf muscle weakness

https://doi.org/10.1016/j.gaitpost.2014.05.016Get rights and content

Highlights

DR-AFOs as prescribed and fitted in clinical practice for polio survivors with calf muscle weakness:• Improved gait biomechanics.• Improved walking speed.• Improved self-perceived walking ability.• May improve walking efficiency, but the overall effect may depend on gait pattern characteristics and orthosis settings.

Abstract

In polio survivors with calf muscle weakness, dorsiflexion-restricting ankle-foot orthoses (DR-AFOs) aim to improve gait in order to reduce walking-related problems such as instability or increased energy cost. However, evidence on the efficacy of DR-AFOs in polio survivors is lacking. We investigated the effect of DR-AFOs on gait biomechanics, walking energy cost, speed, and perceived waking ability in this patient group.

Sixteen polio survivors with calf muscle weakness underwent 3D-gait analyses to assess gait biomechanics when walking with a DR-AFOs and with shoes only. Ambulant registration of gas-exchange during a 6 min walk test determined walking energy cost, and comfortable gait speed was calculated from the walked distance during this test. Perceived walking ability was assessed using purposely-designed questionnaires.

Compared with shoes-only, walking with the DR-AFOs significantly increased forward progression of the center of pressure (CoP) in mid-stance and it reduced ankle dorsiflexion and knee flexion in mid- and terminal stance (p < 0.05). Furthermore, walking energy cost was lower (−7%, p = 0.052) and gait speed was higher (p = 0.005). Patients were significantly more satisfied, felt safer, and less exhausted with the DR-AFO, compared to shoes-only (p < 0.05). DR-AFO effects varied largely across patients. Patients who walked with limited forward CoP progression and persisting knee extension during the shoes-only condition seemed to have benefitted least from the DR-AFO.

In polio survivors with calf muscle weakness, DR-AFOs improved gait biomechanics, speed, and perceived walking ability, compared to shoes-only. Effects may depend on the shoes-only gait pattern, therefore further study is needed to determine which patients benefit most from the DR-AFO.

Introduction

Individuals who were affected by polio at young age often have lasting pareses of their lower extremities. Although the severity of paresis and the muscles involved vary largely between polio survivors, the calf muscles are frequently affected [1], [2]. These muscles play an important role in providing ankle and knee stability during single limb support in walking [3]. If calf muscle strength is insufficient and ankle range of motion is not reduced due to muscle shortening, tibia advancement is accelerated, ankle dorsiflexion is abrupt and/or excessive, and, accordingly, knee flexion in stance is increased [1], [4].

To prevent accelerated tibia inclination and provide weight-bearing stability, patients may change their gait, essentially by avoiding their center of pressure (CoP) to progress anterior of the ankle joint in order to diminish the external dorsiflexion moment at the ankle joint [3], [5]. As a result, the limb is loaded in a more extended position, which can cause joint pain from the accumulated effects of repeated impact [6]. Calf muscle weakness can also induce overuse symptoms such as muscle pain and cramps, and/or, fatigue due to an increased walking energy cost [2], [7]. In combination with dorsal flexor weakness, the risk of tripping or falling may increase [8].

To reduce gait-related problems, polio survivors with calf muscle weakness can be provided with an ankle-foot orthosis that restricts ankle dorsiflexion in stance (DR-AFO), thereby allowing the CoP to shift forward without excessive ankle dorsiflexion [1], [6], [9]. There are two types of DR-AFOs that can do this, a hinged DR-AFO and a posterior leaf spring DR-AFO. The hinged DR-AFO restricts dorsiflexion through a joint with a stop, while allowing free plantarflexion. In the posterior leaf spring DR-AFO, both plantarflexion and dorsiflexion are restricted by the stiffness level of the spring. Beneficial effects of DR-AFOs have been reported in patients with spinal cord injury, myelomeningocele, MS, and stroke [10], [11], [12], [13], [14], although only one study investigated biomechanical effects, as well as functional effects [10]. Studying both these effects is needed to establish DR-AFO efficacy [15], which has not been previously investigated in polio survivors. Because differences in disease characteristics may affect treatment outcome, establishing the efficacy of DR-AFOs in polio is warranted.

The purpose of this study was to investigate the effect of DR-AFOs in polio survivors with calf muscle weakness on different levels of functioning, including gait biomechanics, walking energy cost, speed, and perceived walking ability, compared to walking with shoes only.

Section snippets

Study population

A consecutive series of sixteen polio survivors with paretic calf muscles due to poliomyelitis, who were provided with a DR-AFO during a visit to the outpatient clinic, participated in this study. Inclusion criteria were (a) residual paresis of the plantarflexor muscles due to poliomyelitis (i.e., a MRC score <5 and/or unable to perform ≥3heel rises) as confirmed by the rehabilitation specialist, (b) ability to walk for at least six minutes continuously, (c) a prescription of a DR-AFO at least

Results

Baseline patient and DR-AFO characteristics are shown in Table 1 for each of the 16 patients. Four patients had a posterior leaf spring DR-AFO, 12 had a hinged DR-AFO. Three patients did not use their hinged DR-AFO.

One patient could not complete the shoes-only measurement due to an unrelated illness. This patient only completed the questionnaires about perceived walking ability. Due to technical issues, shoes-only and DR-AFO kinematic and kinetic data from one patient and shoes-only kinetic

Discussion

This is the first study that investigated the effect of DR-AFOs on different levels of functioning in polio survivors with calf muscle weakness. Compared to walking with shoes only, we found improvements with wearing the DR-AFO at the ICF component of ‘body functions and structures’ for forward CoP progression and sagittal ankle and knee kinematics during stance, and at the ICF component of ‘activities and participation’ for gait speed and stride length. Furthermore, the patients' perceived

Conclusion

We demonstrated that in polio survivors with calf muscle weakness, DR-AFOs significantly improved gait biomechanics, speed, and perceived walking ability compared to waking with shoes-only. Moreover, they reduced walking energy cost to nearly significant levels. These findings support the use of DR-AFOs as a treatment option to maintain or improve functional abilities in these patients. Nevertheless, DR-AFO efficacy seemed to vary between patients and may be related to orthosis settings and the

Conflicts of interest

All authors declare that they have no conflict of interests with this publication.

Acknowledgements

We would like to thank C.H.M. van Schie, N.M. Otterman and M.A.N. Siebrecht for their contribution in data collection.

Appendix A. Supplementary material

The purposely-designed questionnaire on perceived walking ability can be found as online supplementary material.

References (30)

  • A. Bickerstaffe et al.

    Circumstances and consequences of falls in polio survivors

    J Rehabil Med

    (2010)
  • F. Nollet et al.

    Orthoses for persons with postpolio syndrome

  • D.J. Bregman et al.

    Spring-like Ankle Foot Orthoses reduce the energy cost of walking by taking over ankle work

    Gait Posture

    (2011)
  • A. Danielsson et al.

    Energy expenditure in stroke subjects walking with a carbon composite ankle foot orthosis

    J Rehabil Med

    (2004)
  • C. Beekman et al.

    The effects of a dorsiflexion-stopped ankle-foot orthosis on walking in individuals with incomplete spinal cord injury

    Top Spinal Cord Inj Rehabil

    (2000)
  • Cited by (33)

    • Energy cost optimized dorsal leaf ankle-foot-orthoses reduce impact forces on the contralateral leg in people with unilateral plantar flexor weakness

      2022, Gait and Posture
      Citation Excerpt :

      Additionally, higher impact forces may increase the external knee flexion moment which might explain quadriceps overload often reported in people with plantar flexor weakness [4]. To improve gait in people with plantar flexor weakness, ankle-foot orthoses (AFOs) are commonly provided [12–14]. In general, AFOs successfully improve walking speed and restrain excessive ankle dorsiflexion, which reduces the downward velocity of the center of mass during the weight shift.

    • Bracing: Upper and Lower Limb Orthoses

      2021, Physical Medicine and Rehabilitation Clinics of North America
    View all citing articles on Scopus
    View full text