Plantar load transfer in children: a descriptive study with two pathological case studies

Masking approaches to analyse plantar pressure data of new and confident walking infants

BACKGROUND

Due to its easy and straightforward use, regional analysis with the "standard" mask is the most common approach for quantifying plantar pressures in infancy. Such a mask, however, identifies foot regions based on typical foot proportions and pressure gradients. Alternatively, the use of a customised mask retaining infants' feet proportions has not been explored.

RESEARCH QUESTION

Does a customised mask scaled on infants' feet improve processing of pressure data collected during walking development compared with a standard mask?

METHODS

Thirteen infants walked across an EMED xl platform. Steps were grouped applying eight foot-regions standard and customised masks. To evaluate masks' performance, peak pressure (PP) and contact area (CA) were extracted from each region, and mask. Intra-individual coefficients of variation were then calculated for each variable, and compared between masks using a Mann-Whitney U test (p < 0.05). Unsuccessful masks application was reported, expressed as percentage of data loss.

RESULTS

For CA variation, significant differences were found in all the regions but the lateral toes in new (Z = -0.184, p = 0.8540) and confident walking (Z = -1.562, p = 0.118). For PP variation, a significant difference was found in confident walking within the lateral midfoot (Z = -2.598, p = 0.009). With the standard mask, 22-27 % of data was lost in new and confident walking respectively, compared to 1.6-0 % with the customised. As a result, the customised mask characterised the more variable steps, demonstrating higher variation compared to the standard mask.

SIGNIFICANCE

Identifying foot regions using a mask based on infants' feet proportions yielded an improved performance compared to the standard mask. With the customised mask, we retained almost all the steps and characterised the variability of the data, thereby providing an appropriate approach for infants' pressure data processing. Application of the customised mask could therefore be beneficial in future studies analysing highly variable data sets.

Kinematic differences in the presentation of recurrent congenital talipes equinovarus (clubfoot)

BACKGROUND

The tibialis anterior tendon transfer (TATT) is the suggested surgical intervention in the Ponseti method for treatment of dynamic recurrent congenital talipes equinovarus (clubfoot) presenting as hindfoot varus and forefoot supination during the swing phase of gait. The indication for surgery, however, is typically based on visual assessment, which does not sufficiently examine the variability of foot motion in this cohort.

RESEARCH QUESTION

The aim of this research was to determine whether subgroups, based on foot model kinematics, existed within a clubfoot cohort being considered for TATT surgery.

METHODS

Sixteen children with recurrent clubfoot that had been previously treated with the Ponseti method and were being considered for tendon transfer surgery were prospectively recruited for this study and were required to attend a pre-surgery data collection session at the Queensland Children's Motion Analysis Service (QCMAS). Data collected included standard Plug-in-Gait (PiG) kinematics and kinetics, Oxford Foot Model (OFM) foot kinematics, and regional plantar loads based on anatomical masking using the integrated kinematic-pressure method.

RESULTS

Results of this study identified two clear subgroups within the cohort. One group presented with increased hindfoot inversion across 91 % of the gait cycle. The second group presented with increased hindfoot adduction across 100 % of the gait cycle. Hindfoot adduction was statistically significantly different between the two groups.

SIGNIFICANCE

The identification of these two groups propose a need for further classification of deformity within this cohort and query the appropriateness of this surgical intervention for both presentations.