Assessment of Five-Foot Plantar Morphological Pressure Points of Children with Cerebral Palsy Using or Not Dynamic Ankle Foot Orthosis

Cerebral palsy (CP) commonly results in gait deviations due to spasticity, motor impairment, balance deficits, and muscle weakness, leading to ankle-foot lever-arm dysfunction and foot deformities. Ankle-foot orthoses (AFOs) are used to control deformity, improve alignment, and promote more normal gait. Dynamic ankle-foot orthoses (DAFOs), which are thin, flexible, and include underfoot arch supports, may influence proximal muscle activity and provide proprioceptive feedback, potentially improving posture and balance. While many studies have evaluated AFO effects on gait kinematics/kinetics, few have examined plantar pressure distribution, and none specifically during DAFO use. The study aimed to evaluate whether DAFOs alter plantar pressure distribution during gait in children with spastic CP, hypothesizing that DAFO use would redistribute plantar loads, particularly increasing lateral/hindfoot activation during stance, and thereby support improved gait function.

Prior work shows various AFO designs (solid, hinged, posterior leaf spring, ground-reaction, DAFO) alter ankle-foot kinematics and kinetics, improving parameters such as stride length, walking speed, ankle dorsiflexion, and reducing pathological plantarflexion and knee hyperextension in children with CP. Systematic reviews report increased ankle dorsiflexion during stance and swing with posterior AFOs and possible improvements in gross motor function. DAFOs, compared with rigid AFOs, may allow greater ankle range of motion, provide underfoot arch support, and distribute plantar loads more evenly, influencing proximal joint mechanics. Plantar pressure studies in CP without orthoses have shown higher pressures in forefoot and midfoot and lower in hindfoot; hemiplegic and diplegic patterns show medial heel and first metatarsal loading differences. However, the literature indicates a gap: plantar pressure distribution during gait with DAFOs has not been well studied, motivating the current investigation.

Design: Within-subject comparison of plantar pressure distribution under two walking conditions: (1) only shoes and (2) DAFO with shoes. Order of conditions was counterbalanced. Participants: Eight children with spastic diplegic CP (age 4–12 years); GMFCS levels I (n=2) and II (n=6); maximum Modified Ashworth Scale spasticity level 3 in ankle muscles. All had received physical therapy. Exclusion: surgery within previous 12 months or botulinum toxin within previous 6 months. Ethical approval: Ankara University Faculty of Medicine IRB (2022-370); informed consent obtained. Orthoses: DAFO3 (n=6) and DAFO4 (n=2), fabricated in the Ankara University Department of Prosthetics and Orthotics by the same experienced clinician. DAFOs were supra-malleolar, thin (approx. 3/32 in polypropylene), flexible devices with contoured footplates, underfoot support for transverse, medial, and lateral longitudinal arches, calcaneal support, toe elevation features (greater elevation for 2nd–4th toes, lesser for 1st), and a 45° Velcro ankle strap to control calcaneal displacement. Plantarflexion block with allowed dorsiflexion via material flexibility; no hinge; posterior coverage up to ~5–7.5 cm above malleoli. Shoes designed for DAFO use were worn in both conditions to standardize footwear. Measurement: Plantar pressure recorded with WalkinSense system (version 0.96, Tomorrow Options Microelectronics, S.A.) using 8 sensors affixed to standard socks. Relevant sensor placements included: #1 under the 1st metatarsal, #2 under the 5th metatarsal, #3 lateral midfoot, #4 lateral heel, #5 medial heel. Dynamic walking trials performed; plantar pressures recorded. For analysis, mid-stance phase pressure values and sensor activation percentages were extracted. Statistics: Descriptive statistics computed. Within-subject comparisons between only shoes vs DAFO with shoes used Wilcoxon signed-rank tests (SPSS v23). Due to small sample and heterogeneity, nonparametric tests were chosen. Significance level p<0.05.

Participants: n=8 children with mild CP; mean age 9 ± 3.3 years; weight 31 ± 10.2 kg; height 126.5 ± 19.2 cm; all right-leg dominant. Primary outcomes (mid-stance): - Maximum pressure (kg/cm²): only shoes 1.99 vs DAFO with shoes 1.71 (p=0.123; not significant). - Maximum pressure sensor location: only shoes sensor 2 (5th metatarsal) vs DAFO with shoes sensor 3 (lateral midfoot) (p=0.037; significant shift). Sensor activation percentages: - Sensor 1 (1st metatarsal): decreased from 92% (only shoes) to 24.5% (DAFO) (p=0.028). - Sensor 4 (lateral heel): increased from 58% to 90% (p=0.036). - Sensors 2, 3, and 5: changes not statistically significant (p=0.161 each in reported comparisons), though sensor 3 median activation increased numerically (81% to 88%). Interpretation: Without DAFO, higher activation at sensors 1, 2, and 3 indicated greater forefoot and medial-lateral midfoot loading. With DAFO, decreased 1st metatarsal activation and increased lateral heel activation indicate a lateral/posterior shift of plantar load during stance, suggesting more even pressure distribution and enhanced lateral hindfoot engagement.

The DAFO’s design—arch support, toe elevation, and mediolateral stabilization with controlled ankle motion—appears to redistribute plantar loads during stance, decreasing forefoot (1st metatarsal) activation and increasing lateral heel activation. This aligns with DAFO’s goals to manage equinus/crouch features by promoting dorsiflexion control and reducing abnormal plantarflexion. Prior literature shows AFOs can improve gait kinematics and kinetics (e.g., increased dorsiflexion in stance/swing, reduced knee hyperextension), and DAFOs may allow greater ankle range than rigid AFOs. The observed shift of maximum pressure from the 5th metatarsal region to lateral midfoot and increased hindfoot activation may reflect improved roll-over and base of support, potentially mitigating midfoot break and supporting lever-arm function in CP gait. Given reports of forefoot/midfoot overloading and hindfoot underloading in CP, DAFO-induced redistribution toward the hindfoot/lateral structures could be beneficial for stability and energy efficiency. This study adds novel evidence using plantar pressure distribution to assess DAFO effects during gait, complementing traditional gait analysis findings.

DAFO use in children with mild spastic CP altered plantar pressure distribution during gait, decreasing forefoot (1st metatarsal) activation and increasing lateral heel activation in mid-stance, with a significant shift of the location of maximum pressure. These findings indicate that DAFOs may improve the gait cycle by promoting more even plantar load distribution and influencing foot motion. Future research should include larger cohorts, long-term follow-up, and direct comparisons with other orthotic designs to determine optimal prescriptions and their functional impacts.

- Small sample size (n=8) and participant heterogeneity limit statistical power and generalizability. - Short-term assessment only; long-term effects of DAFO on function and plantar pressures were not evaluated. - No direct comparison with other orthotic designs in plantar pressure outcomes; only DAFO versus shoes was tested.