Two Boys with Idiopathic Toe Walking Treated with Different AFO Design

Jenny McEwen-Hill, Don Weber


Introduction

Idiopathic toe walking (ITW) in children can lead to limitations in activity and participation in the long term. It is unclear whether the best treatment approach should be conservative or surgical. Two boys who presented with ITW, and who had conservative management including the use of two different AFO designs are described. They were referred for physiotherapy assessment. Both were toe walking 100% of the time, one with contracture (range of motion less than 0 degrees dorsiflexion (DF)) of the gastrocnemius and soleus and, one with decreased range of motion (range of motion above 0 degrees DF but less than normal range). One boy was followed for 3 years and one for 5.5 years. Conservative interventions tried had varying degrees of success. The natural history of their problem has shown a predisposition to sustained toe walking and loss of muscle length.

Case Studies

These patients followed by the authors were selected because they both had positive outcomes following the use of two different AFOs, with improvement in gait, range of motion, activity and participation. The dates and data shown in Figure 1 and Figure 2 are not a reflection of the frequency that they were seen and do not contain all of the details of the physiotherapy treatment given. R1 (first catch) and R2 (muscle length)1,2 passive range of motion measures were done for dorsiflexion with knee extension, but for the purpose of this presentation, only R2 is reported.

Case Study 1 describes a nine year old boy, diagnosed as an idiopathic toe walker by a paediatric neurologist. He has been a toe walker since he began walking. His gross motor milestones were normal. He was assessed by a physiotherapist at age 7. He walks on his toes unless requested to walk normally. He is active recreationally, playing hockey, soccer, cycling, and swimming. He had intensive physiotherapy, 2 times per week for 8 weeks, with a home program including tibialis anterior strengthening, balance exercises, functional and passive stretching of hamstrings and gastrocnemius. (Figure 1 ) There was no change in his gait or muscle length during this time. Serial casting was done for four weeks, with the cast being changed or wedged weekly. He was then seen once per week for four weeks with a program of stretching, strengthening, and gait training, to be done daily at home. Three months later, a night time ankle resting splint was dispensed to be used with a leg gaitor for sustained passive stretching of the gastrocs. Sixteen months later he was fitted with hinged AFOs with dorsi assist joints and no PF stop. They were to be worn day and night, except for sports. One month later, he was wearing his AFOs 23 hrs/day and there was a significant increase in range of motion. With the AFOs, he was never up on his toes when walking. His heels were raised 50% of the time when standing in the AFOs. Ten months after the AFOs, he had improved speed of running and skating with further increase in range of motion. In summary, intensive training with stretches, strengthening and gait training did not change his range of motion. Serial casting was successful in reducing toe walking, but did not last. Wearing of hinged AFOs with dorsi assist joints and no PF stop day and night showed greatest change in range of motion.

Case Study 2 describes a ten year old boy diagnosed as an idiopathic toe walker by a paediatric neurologist. He has been a toe walker since he began walking. His gross motor milestones were normal. There is a paternal family history of toe walking. He was assessed by a physiotherapist at age 5 and was found to have difficulties with heel toe walking unless his knees were hyper extended and his hips flexed. He was active recreationally, playing t-ball, soccer, skating, and swimming. Serial casting was done for 8 weeks, with the casts changed or wedged weekly (Figure 2 ). Hinged AFOs with PF stop were dispensed and were to be worn 20 hours per day. He was seen weekly for 4 weeks with a program of stretching, strengthening and gait training, to be done daily at home. After one year with the hinged AFOs with PF stop, he was very frustrated as they did not allow normal jumping and running. Supramalleolar orthoses (SMOs) were dispensed for daytime and the AFOs were used for night time for sustained passive stretching. Three months later skating skills and running speed were improved. He was now walking with an early heel rise. Six months later he had an increased lumbar lordosis. He could not stand with heel contact on the right. One year later he was injected with 100U Botox™ to each gastroc. There was no change in gait or range of motion with Botox™ after 1 month. Two months after Botox™, he had serial casting for 4 weeks. Energy storage and return (ESR) AFOs were dispensed, and were to be worn at all times. Three weeks later, AFOs were worn for cross-country running, and the school basketball team. Two months after receiving ESR AFOs, he had a better push-off with hockey skating. One year after the AFOs, he had decreased range in gastrocs at the same time as rapid growth. His skate blade makes full contact with ice for the first time ever. In summary, serial casting was effective initially to increase range of motion but was not as effective the second time. Toe walking has continued, although was reduced with wearing of the ESR AFOs, which increased his range of motion more than casting itself.

The hinged AFO (Fig. 6 ) used in the first case study has no plantarflexion stop. It uses preflexed ankle joints to create the dorsiflexion assist needed to inhibit plantarflexion. The strength of the dorsiflexion assist can be varied by choosing the size (paediatric, medium, or large), the durometer (75, 85, 95) and the number of joints used (medial, lateral or both). The ideal stiffness of the joints is the least amount possible to prevent toe walking during normal every day walking and low force activities. During running, sports and other high force activities, the orthosis should not restrict the ankle plantarflexion needed for forward propulsion. The hinged AFO successfully prepositions the foot in dorsiflexion producing the three rockers of normal gait during walking (Fig. 3 ) and running (Fig. 4 ). The absence of a plantar stop in the orthosis allows plantarflexion for forward propulsion during terminal stance in walking (fig 3C2 ) and the generation phase of running (figure 4C2 ). A dynamic stretch of the triceps surae muscle using body weight forces was also observed. (Figure 3B2 and Figure 4B2 ).

The design of the ESR (energy storage and return) AFO (Fig. 7 ) used in Case Study 2 incorporates polypropylene reinforcements in the posterior leaf and plantar surfaces of the orthosis. The stiffness due to the shape and thickness of the posterior leaf is designed to create a dynamic control of ankle dorsiflexion/plantarflexion best suited to the person's weight and activity level. The ESR AFO mechanically controls ITW in the same way as the hinged AFO with one notable exception. At terminal stance in walking (Fig. 5A ) and generation phase in running (Fig 5B ) the ESR AFO resists forward tibial progression. The inertia of the body above the knee results in a knee extensor moment creating a stretch on the gastrocnemius muscle.

Both orthoses inhibit ITW without restricting the close to normal plantarflexion needed for propulsion in running and other high force activities. For Case Study 1, the hinged AFO with no PF stop was chosen because he was not on his toes 100% of the time, and shortening of the gastrocnemius was minimal. It was felt that he would benefit from the large range and minimal restriction provided by the hinged AFO. The ESR AFO was used in Case Study 2 because this boy had a very strong predisposition to walking on his toes 100% of the time when not concentrating. He has always had stiffer shorter muscles. The increased stiffness of the ESR AFO was more appropriate to resist the shorter, stiffer and overactive gastrocnemius.

Discussion

Previous studies have provided little detail about the role of the authors' respective disciplines in the treatment of these children. The terms physiotherapy, bracing/orthoses and stretching do not describe what has been done. These two case studies have examined in more detail the role of two different brace designs in improving range of motion and gait in two children. The authors believe that the improvement in gait from the use of the orthoses (Figure 3 , Figure 4 , and Figure 5 ) is three- fold: it improves function, provides a dynamic stretch of the muscle and provides a motor learning/gait training effect by reinforcing a normal gait pattern.

The importance of dynamic stretch has been recognized for some time by the Tardieus who provided the only data so far on how many hours of dynamic stretch per day must be done to prevent contracture in children with CP.3 Uncertainty remains about the mechanism of this change in muscle length and why it is better with dynamic stretch.4 Gorter et al5 describe how all types of stretching need to be integrated in a child's day with the end result to improve or maintain the children's activities and participation. The orthoses both provide a dynamic stretch with walking and a sustained passive stretch when used at night time with a gaitor.

In Case Study 1, attempts at gait training without an orthosis were unsuccessful in improving range of motion and it was not until the hinged AFO with DF assist and free PF was applied that he had a sustained change in his range of motion and significant change in his gait (Feb 08, Fig. 1 ). Presently he can walk without his AFOs for short periods of time and not exhibit toe walking. At a recent appointment, he expressed that he was not yet ready to stop using the AFOs in case toe walking returned. In Case Study 2, hinged AFOs with plantarflexion stops were dispensed early in the treatment programme (Oct 03, Fig 2 ). They were useful for night time sustained passive stretching, but only functioned to maintain his range of motion. Better compliance in using the current ESR AFOs compared to the previous hinged AFOs (with PF stops), caused the greatest increase in range of motion to date. Without orthoses, the second boy continues to walk on his toes unless he is aware that he is being observed.

Both boys can demonstrate normal gait, but for an unknown reason, cannot sustain this gait pattern. Motor learning for them does not seem to have moved to the automatic phase where this skill is mediated by non-conscious processes.6 In Case Study 2, the initial application of the hinged AFO with PF stop (Oct 03, Fig 2 ) had a significant and adverse effect on this child's gross motor function and ability to participate, resulting in the rejection of this device. At present he would rather not wear his AFOs, but also does not wish to return to his previous toe walking and contracted state. With use of the recent AFOs and the subsequent improvement in range of motion, both boys reported improvement in performance of sports and speed of running.

Toe walking may be seen in children under the age of 2 as a normal variant in the development of gait. Heel strike is present in most children by age 18 months,7 but in some toddlers, toe walking remains with growth and age. Idiopathic toe walking is a diagnosis of exclusion and a condition that occurs in children of unknown cause, characterized by the persistence of a toe-toe gait pattern in the absence of neurological, orthopaedic or other cause.8 There is sometimes limitation of passive range of motion for dorsiflexion with knee extension9,10 and it has not yet been determined if muscle shortening has been there since birth or developed as a result of the toe walking.11

In a recent study, children with ITW were studied using gait analysis and significant deviations in both kinematics and kinetics at the level of the ankle were identified. When requested, 17% of children could normalize stance and swing variables.12 Hicks et al13 demonstrated a more variable pattern of ankle motion in children with ITW with significant plantar flexion during stance phase. Policy et al14 found that there was premature firing of the gastrocs in swing in children with ITW. Normal children who are asked to toe walk have the same gait pattern as those who are ITW.15

There is limited literature on the treatment of idiopathic toe walking. It is not clear how treatment was selected for each child and it is possible that the least affected were mostly in the untreated group and the most affected mostly in the surgical group. Studies of children who had surgical lengthening of tendo Achilles had sample sizes of 15 to 20 children.8,16,17,18 Surgical intervention8,16,17,18 resulted in improvements in gait, but gait abnormalities remained17 and some children were still toe walking. Hemo et al18 found significant improvement in mean ankle dorsiflexion in stance and maximum swing phase ankle dorsiflexion after surgery. Peak ankle power generation increased but did not reach normal levels at one year post surgery.18

Stricker et al,19 Eastwood et al20 Stott et al21 did comparative studies on three different treatment modalities: observation, cast/brace treatment or surgical lengthening of triceps surae. Comparisons of the treatments showed that with no treatment or casting/splinting, there was some improvement, but not to the same degree as surgery.19,20,21 Serial casting alone showed improvement in gait and range of motion for the short term.22,23,24 A group of young children where found to have good results with Botox™, with the majority of children having a heel toe walking pattern 12 months following the injections.25

Conclusions

Previous studies do not provide any conclusive recommendations that correct idiopathic toe walking. Surgeons might argue that they can achieve permanent results with muscle or the tendo Achilles lengthening. However, in these case studies, the conservative intervention of using orthoses has demonstrated benefits without the resulting loss of strength of surgery. We do not know the long-term result of using these devices. It will be interesting to continue to follow children prescribed with AFOs over the long term to determine if and when they are able to walk normally without these devices. Because there is so little understood about the etiology of ITW, choosing the correct intervention is challenging. We believe that there may be distinct types of children with ITW and have chosen to use two different devices to reflect this. Further research is required to determine how to manage ITW. In presenting these two case studies of children, it is hoped that we have provided more detail about the possible interventions of a physiotherapist and orthotist in the management of ITW and that these particular devices will be considered if "bracing" is determined to be the best intervention.

References

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Jenny McEwen-Hill (PT)

Don Weber CO(c)