Classification of idiopathic toe walking based on gait analysis: Development and application of the ITW severity classification

Abstract

Idiopathic toe walking (ITW), considered abnormal after the age of 3 years, is a common complaint seen by medical professionals, especially orthopaedic surgeons and physiotherapists. A classification for idiopathic toe walking would be helpful to better understand the condition, delineate true idiopathic toe walkers from patients with other conditions, and allow for assignment of a severity gradation, thereby directing management of ITW. The purpose of this study was to describe idiopathic toe walking and develop a toe walking classification scheme in a large sample of children. Three primary criteria, presence of a first ankle rocker, presence of an early third ankle rocker, and predominant early ankle moment, were used to classify idiopathic toe walking into three severity groups: Type 1 mild; Type 2 moderate; and Type 3 severe. Supporting data, based on ankle range of motion, sagittal joint powers, knee kinematics, and EMG data were also analyzed. Prospectively collected gait analysis data of 133 children (266 feet) with idiopathic toe walking were analyzed. Subjects’ age range was from 4.19 to 15.96 years with a mean age of 8.80 years. Pooling right and left foot data, 40 feet were classified as Type 1, 129 were classified as Type 2, and 90 were classified as Type 3. Seven feet were unclassifiable. Statistical analysis of continuous variables comprising the primary criteria showed that the toe walking severity classification was able to differentiate between three levels of toe walking severity. This classification allowed for the quantitative description of the idiopathic toe walking pattern as well as the delineation of three distinct types of ITW patients (mild, moderate, and severe).

Introduction

Toe walking is a common pattern seen in normal children less than 3 years old [1] and as a pathological pattern in neuromuscular conditions [2] and structural deformities [3]. As an isolated gait abnormality, it is known as idiopathic toe walking (ITW). It is generally accepted that idiopathic toe walkers are normal children (older than 3 years) who are observed to walk on their toes [1]. From a referring physician's perspective, anecdotal descriptions of toe walking include “walking on toes” and “bouncy gait.” Orthopaedic surgeons and physiotherapists describe toe walking in terms of decreased ankle range of motion and inability to heel strike at the initial contact of gait [4].

Gait analysis provides a further objective, quantitative description of toe walking. A number of studies have evaluated toe-walking patterns using gait analysis data [5], [6], [7], [8]. There are two approaches to describing toe walking using gait analysis: (1) delineate the entire spectrum of disorders that represent toe walking or (2) restrict the description exclusively to idiopathic toe walking. Many authors have reported toe walking in patients with cerebral palsy, describing gait patterns based on the ankle [5], [6] or knee [7]. A study by Armand et al. identified three distinct patterns of toe walking but their classification could not distinguish between etiologies of toe walking (ITW, cerebral palsy, and clubfoot) and different patient populations were heterogeneously represented across the three patterns [8]. Kelly et al.'s description of toe walking patterns differentiated children with mild spastic diplegia and idiopathic toe walking using kinematic data [9]. The approach used by authors in these previous papers was to describe toe walking within the context of other diseases and differentiate toe-walking patterns between different diagnoses. This contrasts to the approach taken in this study, which was to evaluate idiopathic toe walking exclusively.

There are few exclusive descriptions of ITW in the literature [10], [11], [12], [13]. Papers have either provided descriptive clinical reports including patient family histories, clinical range of motion, and qualitative description of toe walking patterns [10], [12] or used EMG studies to describe idiopathic toe walking in the context of cerebral palsy and/or normal children [11], [13]. Study samples in these previous reports have been quite small, ranging from 6 to 60 children. Within these referenced studies, there were noted ranges of severity in the variables they used to describe ITW [10], [11], [12], [13]. There are also patterns or constellations of abnormal features, for example ankle rocker formation, ankle range of motion, and excessive gastrocnemius activity, that represent toe walking [14]. These suggest that there is a spectrum of severity seen in ITW.

The purpose of this paper was to describe idiopathic toe walking pattern using gait analysis. Two-fold study objectives were to: (1) develop a toe walking severity classification for idiopathic toe walking and (2) apply the classification to a large sample of idiopathic toe walkers.