Effects of the Twin Shoe (Darco) to compensate height differences in normal gait
Introduction
Load-relieving shoes are used both in post-surgical treatment of foot injuries or in foot pathologies, such as rheumatoid arthritis or diabetes, and for prevention of foot overloading problems, e.g. causing ulceration [1], [2], [3], [4]. Several shoe designs exist, including healing sandals, removable walking boots and ankle-foot orthoses [3]. These shoe designs are supposed to protect regions at risk from overloading and to support the healing process while maintaining the ability to walk. Bus et al. [5] emphasized that forefoot off-loading shoes are effective in relieving the forefoot and in supporting the healing of a diabetic foot, however, walking comfort is compromised. A reason for the discomfort could be that many relieving shoe types such as the Ortho Wedge Healing Shoe™ or the Wound Care Shoe System (WCS™) manufactured by Darco (Europe) GmbH have an elevated sole. If they are worn unilaterally they result in a functional leg length discrepancy causing discomfort as normal gait is disturbed [3].
Limb length discrepancy provokes mechanical and functional alterations in gait and postural sway, supination deformity of the foot of the short leg, changes in joint moments and powers as well as pelvic obliquity that can lead to degenerative disorders in the hip and deformities in the spine [6]. Therefore, in the long term, pain occurs in the contralateral leg [3]. Furthermore, patients with postural impairments are at an increased risk to fall while walking with soles of different heights [3]. There is evidence that limb length discrepancy stresses the structures of the lower back, however, a correlation to low back pain remains unclear [7]. An elevated shoe is related to a moderate or severe limb length discrepancy and can therefore lead to the consequences described before. Therefore, a temporary adjustment of the contralateral sole of the shoe is recommended to compensate the height difference [8], [9], [10] and to avoid an asymmetrical gait pattern.
As a solution to this problem Darco developed the Twin Shoe as a partner to Darco's orthopaedic shoes with an elevated sole. The Twin Shoe is currently available at Darco (Europe) GmbH. It suits the Ortho Wedge Healing Shoe™ and the Wound Care Shoe System (WCS™). Worn on the contralateral leg, the Twin Shoe aims to compensate height differences in normal gait so that an elevation of the sole of the patient's normal shoe is no longer necessary. The aim of this study was to investigate the efficacy of using the Twin Shoe in combination with the WCS™ and the Wedge Shoe™ on biomechanics in normal gait. It was hypothesized that using the Twin Shoe would lead to a significant reduction of gait asymmetry.
Section snippets
Subjects
Fifteen healthy subjects – 4 women and 11 men – took part in the study. Their mean age was 26.1 (±9) years with a range between 17 and 56 years (Table 1). The participants were recruited from several faculties of the local university and personal contacts. After being informed about the aims and procedures of the measurements they gave consent. The study was approved by the ethical committee of the medical faculty of the local university.
Medical footwear
In this study three shoe products manufactured by Darco
Results
Wearing an elevated shoe (WCS or Ortho Wedge) caused a significantly increased hip adduction and pelvic tilt upwards on the ipsilateral side. By using the Twin Shoe a significant compensation was observed (Table 4 and Fig. 2a and b).
Furthermore, hip flexion in the elevated leg and hip extension in the contralateral leg were increased in both normal shoe conditions. These asymmetries were compensated by wearing the Twin Shoe (Table 4). The trunk was increasingly tilted forward in normal shoe
Discussion
The aim of this study was to investigate the effects of using the Twin Shoe in combination with elevated orthopaedic shoes on the biomechanics of normal gait. Results showed that walking in orthopaedic shoes without an elevated sole on the contralateral foot led to apparent gait alterations. The subjects demonstrated significantly asymmetrical movement patterns at the hip in the frontal plane, the knee and the foot in the sagittal plane. The greater hip flexion in the elevated leg could be
Conclusion
In conclusion, wearing a therapeutic shoe without compensation on the contralateral limb leads to significantly asymmetric movement patterns and loads in the lower extremity and the lower back. The application of the Twin Shoe as a partner shoe led to an almost complete compensation of these asymmetries and a more symmetrical gait pattern compared to wearing a normal shoe. A complete compensation was not achieved but all joint movements were more symmetrical, forces and moments were reduced and
Conflict of interest
Financial and material support of the study was provided by Darco (Europe) GmbH.
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