" Study will investigate the immediate effect of DAFO usage on balance and gross motor functions in individuals with spastic diplegic cerebral palsy. The study is planned to be conducted with children aged 4-15 who have GMFCS levels 1 and 2 and who are willing to participate along with their families at the Turkey Spastic Children Foundation Metin Sabancı Special Education and Rehabilitation Center. During the dates of the study, children who meet the inclusion criteria will be evaluated. Demographic information such as age, height, and weight will be obtained for the participating children. To classify the gross motor levels of the children, the Gross Motor Function Classification System (GMFCS), the Manual Abilities Classification System (MACS) for hand skills, the Communication Function Classification System (CFCS) for communication skills, and the Eating and Drinking Ability Classification System (EDACS) for feeding skills will be used. In addition, the Gross Motor Function Measure (GMFM-88) items D and E for assessing motor skills, the Wii Balance Board for testing balance, the Pediatric Berg Balance Scale, and the functional reach test will be utilized. The balance and gross motor functions of the included children will be assessed in two different ways: with and without DAFO. Data analysis will be conducted by a blinded statistician who is not part of the research team. IBM SPSS 26 (Statistical Package for Social Sciences) will be used for statistical analysis of the data. Normality of continuous variables will be assessed using the Kolmogorov-Smirnov test. If continuous variables follow a normal (parametric) distribution, paired sample t-tests will be conducted on pre-test and post-test data. If the data are non-parametric, Wilcoxon test will be used. Pearson chi-square test or Spearman correlation coefficient will be used to determine the relationship between variables based on assumptions. Results will be evaluated at a significance level of p < 0.05 with a 95% confidence interval."

Cerebral Palsy (CP) is a group of motor disorders resulting from non-progressive damage to the immature brain, leading to movement and posture impairments. Approximately 2 to 3 out of every 1000 children worldwide are born with CP. Prevalence studies conducted before 1990 reported an increasing trend in CP prevalence. However, prevalence is not static, and improvements in prenatal care due to advancements in healthcare have led to a slight decrease in prevalence. A study in 2013 reported a prevalence rate between 2.2% and 2.3%.

Children with CP exhibit various symptoms such as contractures, spasticity, and coordination disorders, mainly affecting the musculoskeletal and nervous systems. These symptoms adversely affect their mobility, functional abilities, and quality of life.

CP is classified into three types based on movement disorder: spastic, dyskinetic, and ataxic, and into four classes based on the pattern of involvement: quadriplegic, hemiplegic, diplegic, and monoplegic. Among these, diplegic CP is the most common type, accounting for 30-35% of cases. Diplegic CP primarily affects the lower extremities more than the upper extremities. Children with diplegic CP often exhibit a pathological gait characterized by pes equinovarus, genu valgus, excessive knee flexion, increased hip adduction, and internal rotation.

The management of CP involves physiotherapy, orthotic support, surgeries, temporary medical interventions, and speech-language therapy. Orthoses, such as Ankle-Foot Orthoses (AFOs), are commonly used in CP rehabilitation. Dynamic Ankle-Foot Orthoses (DAFOs) have emerged as a popular alternative to AFOs in diplegic CP. DAFOs are designed to control muscle tone and prevent foot deformities by providing proper support to the foot's plantar surface. They allow for partial movement due to their flexible and thinner structure compared to rigid AFOs.

Studies have shown that DAFOs significantly impact gross motor skills in children with CP. DAFOs aim to manage foot deformities, increase support, facilitate skill training, and improve mobility during standing and walking.

1. Examine the effect of DAFO use on balance in children with diplegic CP.
2. Investigate the effect of DAFO use on lower extremity gross motor functions in children with diplegic CP.
3. Explore the impact of DAFO use on functionality in children with diplegic CP.

Upon obtaining meaningful results, this study aims to contribute to clinical practice and scientific research in the field of CP rehabilitation.

**Materials and Methods / Design**

**Sample Size:** The sample size of this study was determined based on a power analysis conducted using data from a similar study. With a significance level (α) of 0.05, power (1- β) of 0.90, and effect size (Cohen's d) of 0.97, it was calculated that a total of 38 patients would be sufficient to detect the difference. However, considering possible withdrawals or issues with completing the analysis, the sample size was set at a minimum of 40.

**Procedure:** The study will be conducted with the participation of children aged 4-15 diagnosed with cerebral palsy (CP) at levels 1 and 2 according to the Gross Motor Function Classification System (GMFCS) at the Metin Sabancı Special Education and Rehabilitation Center for Children with Spastic Disabilities in Turkey. The evaluation will take place among children who meet the predefined inclusion criteria during the specified dates.

Demographic information such as age, height, and weight will be collected for the participating children. Classification systems such as the Gross Motor Function Classification System (GMFCS) for assessing gross motor function, the Manual Ability Classification System (MACS) for assessing manual abilities, the Communication Function Classification System (CFCS) for assessing communication abilities, and the Eating and Drinking Ability Classification System (EDACS) for assessing eating and drinking abilities will be used. Additionally, the Gross Motor Function Measure (GMFM), Pediatric Balance Scale (PBS), and functional reach test will be employed to evaluate motor skills and balance. The children's balance and gross motor functions will be assessed using different evaluation methods with and without the use of Dynamic Ankle Foot Orthoses (DAFOs).

Inclusion Criteria:

• Diagnosed with Spastic Diplegic type of cerebral palsy
• Age between 4 and 15 years
• Using bilateral Dynamic Ankle-Foot Orthosis (DAFO)
• Communication Function Classification System (CFCS) level between 1 and 2
• Gross Motor Function Classification System (GMFCS) level between 1 and 2
• Willingness to participate in the study

Exclusion Criteria:

• Having experienced lower extremity fractures or muscle-tendon and bone surgery in the past 6 months, or having undergone spinal or orthopedic surgery affecting the lower extremities
• Exposure to any pharmacological agent or intervention inhibiting spasticity in the past 6 months.

Children with spastic diplegic cerebral palsy who are independently walking and aged between 4 and 15 years.