The Effects of Body Weight Supported Treadmill Training on Balance Abilities and Activities of Daily Living in Children with Spastic Cerebral Palsy following Orthopedic Surgery in the Lower Extremities

Abstract

Purpose : This study aimed to examine the effects of body weight supported treadmill training on balance ability and performance of activities of daily living in children with spastic cerebral palsy who had undergone lower-limb orthopedic surgery, and to compare training effects between those who received muscle lengthening alone and those who underwent combined surgery involving muscle lengthening and osteotomy. Methods : Participants were children diagnosed with spastic cerebral palsy who had undergone either muscle lengthening surgery or combined muscle lengthening and osteotomy. Both groups received body weight supported treadmill training in addition to conventional therapy, three times per week for 30 minutes per session over a 10-week period. Balance ability was assessed using the Korean version of the trunk control measurement scale, and activities of daily living were evaluated using the functional independence measure for children. Results : Both groups demonstrated significant improvements in overall balance ability and performance of activities of daily living following training. In the muscle lengthening group, significant gains were observed in static sitting balance, dynamic sitting balance, self-care, and mobility domains. This group also showed greater improvements than the combined surgery group in dynamic sitting balance, dynamic reaching, total balance score, self-care, and total activities of daily living score. In contrast, the combined surgery group exhibited significant improvement only in static sitting balance and mobility. The superior outcomes in the muscle lengthening group may be attributed to a shorter immobilization period after surgery, enabling earlier gait training and functional movement practice. Conclusion : Body weight supported treadmill training is an effective rehabilitation strategy for improving balance ability and activities of daily living in children with spastic cerebral palsy following orthopedic surgery. The findings suggest that early rehabilitation intervention, particularly after procedures with shorter immobilization periods, can optimize functional recovery in this population.

Ⅰ. Introduction

Cerebral palsy (CP) is defined as a group of permanent disorders of movement and posture causing activity limitations, attributed to non-progressive disturbances that occurred in the developing fetal or infant brain (Rosenbaum et al., 2007). Among the various subtypes, spastic cerebral palsy is the most common, characterized by increased muscle tone (spasticity) and impaired motor coordination (Vitrikas, 2020). In addition to these motor impairments, children with cerebral palsy often experience a wide range of comorbidities, including sensory, perceptual, cognitive, communication, and behavioral disorders, epilepsy, and secondary musculoskeletal problems (Barakat et al., 2021; Sadowska, 2020). Such complex functional limitations increase the challenges of treatment, necessitating comprehensive and multidisciplinary intervention strategies (Novak et al., 2017).

Spastic cerebral palsy is strongly associated with preterm birth or low birth weight and frequently presents bilaterally (Stavsky et al., 2017). These children often have low trunk muscle tone combined with spasticity in the lower limbs, resulting in difficulties with postural control and inefficient compensatory movements of the head, upper limbs, and trunk during gait (Heyrman et al., 2014). Over time, these motor control impairments can lead to secondary musculoskeletal problems, becoming a major factor limiting functional independence and participation in daily activities (Novak et al., 2013).

The primary orthopedic problems in children with cerebral palsy arise from abnormal muscle tone, inefficient force generation, abnormal stretch reflexes, and asymmetrical weight bearing (Damiano et al., 2000). Consequently, deformities often develop in the spine, hip, knee, and ankle joints (Shore & Graham, 2017). In clinical practice, orthopedic surgery is performed to correct such deformities early, restore proper body alignment, and improve functional movement. Surgical interventions for children with cerebral palsy can be broadly classified into soft tissue surgery and bony surgery, each with distinct purposes and techniques (Graham et al., 2016).

Muscle lengthening and tendon lengthening aim to increase joint range of motion, improve flexibility, and enhance functional alignment during gait (Sharan, 2017). Muscle lengthening, often performed on the calf muscles, helps achieve heel contact with the ground, thereby improving gait stability. Tendon lengthening addresses shortened tendons to improve joint mobility and prevent deformity progression. In contrast, bony procedures such as osteotomy are performed to correct abnormal rotation or malalignment by cutting and realigning the bone, thereby improving posture and mobility (Carty et al., 2014). For example, femoral derotation osteotomy can improve gait symmetry and stride length.

Orthopedic surgery plays a crucial role in correcting lower-limb deformities, restoring alignment, and improving postural stability and functional mobility in children with spastic cerebral palsy. However, surgery alone cannot fully restore motor function. In the immediate postoperative period, weight-bearing restrictions and muscle weakness often limit independent ambulation (Miller et al., 2021). At this stage, appropriate gait rehabilitation is essential for relearning normal gait patterns and restoring balance (AI Shami, 2024). Early postoperative rehabilitation is also critical to prevent muscle atrophy and integrate surgically achieved biomechanical alignment into functional movement.

One intervention that meets these objectives is body weight-supported treadmill training (BWSTT). Body weight-supported treadmill training is a task-oriented training method in which a portion of the body weight is supported (Macko et al, 2001; Visintin et al., 1998), enabling children to safely perform repetitive and rhythmic walking practice (Begnoche & Piett, 2007). By reducing gravitational load, body weight-supported treadmill training can effectively improve muscle strength, endurance, balance control, gait rhythm, and symmetry, as well as enhance selective motor control and coordination (Grecco et al., 2013).

Although several studies have reported the effects of body weight-supported treadmill training, few have compared the differences in training outcomes according to orthopedic surgical technique in children with spastic cerebral palsy who have undergone lower-limb surgery. However, most previous studies on the effects of body weight-supported treadmill training after orthopedic surgery in children with spastic cerebral palsy have either analyzed a single group based solely on the presence or absence of surgery or grouped various surgical techniques together without distinction (Grecco et al., 2013). Such approaches fail to account for the differences in biomechanical correction mechanisms between muscle lengthening procedures and osteotomy, and do not adequately explain the variations in postoperative recovery processes and gait re-learning patterns. For example, muscle lengthening primarily focuses on increasing muscle–tendon length and flexibility, thereby improving joint range of motion and gait patterns, whereas osteotomy corrects bony alignment and rotational deformities, directly influencing weight-bearing and gait symmetry.

In this context, distinguishing the effects of body weight-supported treadmill training according to surgical type (on recovery speed, balance strategies, and improvements in functional mobility) is critical for the development of optimal postoperative rehabilitation protocols and the establishment of individualized treatment plans tailored to each patient. Despite this clinical relevance, there is a notable lack of studies directly comparing the effects of body weight-supported treadmill training by surgical type, highlighting the significance of the present study in addressing this gap in the literature and providing evidence-based guidance for rehabilitation practice.

Therefore, the present study aimed to investigate the effects of body weight-supported treadmill training on balance ability and activities of daily living (ADL) in children with spastic cerebral palsy following lower-limb orthopedic surgery, and to compare outcomes between a muscle lengthening group and a combined surgery group (muscle lengthening plus osteotomy). Additionally, this study seeks to provide clinical evidence for the use of body weight-supported treadmill training as an effective rehabilitation program to promote functional recovery and independence in children with spastic cerebral palsy after orthopedic surgery.

Ⅱ. Methods

1. Study design

This quasi-experimental study employed a non-equivalent control group pretest–posttest design to examine the effects of body weight-supported treadmill training on balance ability and activities of daily living in children with spastic cerebral palsy, according to different lower-limb orthopedic surgical techniques. Participants were allocated into two groups based on the type of orthopedic surgery previously performed: (1) a muscle lengthening group, in which surgery was performed to elongate spastic lower-limb muscles, and (2) a combined surgery group, in which both muscle lengthening and osteotomy for bone realignment were conducted. Both groups received the same body weight-supported treadmill training, and their balance ability and performance of activities of daily living were assessed before training and after 10 weeks of training, with analyses conducted within and between groups.

2. Participants

Fourteen children diagnosed with spastic cerebral palsy by specialists in rehabilitation medicine or neurology/neurosurgery were recruited using a snowball sampling method through healthcare institutions, welfare centers, and private rehabilitation facilities in the Busan–Gyeongnam region

Inclusion criteria were as follows: (1) age between 6 and 12 years with spastic diplegia; (2) gross motor function classification system (GMFCS) levels II–III; (3) history of either lower-limb muscle lengthening surgery alone or combined muscle lengthening and osteotomy; (4) at least three months post–lower-limb orthopedic surgery; and (5) ability to understand and follow the researcher’s instructions.

Exclusion criteria included: (1) visual–perceptual or cognitive impairments limiting participation in body weight-supported treadmill training; (2) cardiopulmonary disease; and (3) postoperative complications such as bone sclerosis, infection, or pressure ulcers. The participants’ general and medical characteristics are presented in Table 1.

Table 1. General characteristics and medical history of the participants

Numbers indicate frequency (n), data are expressed as mean±standard deviation, LLL and RLL ; the number of surgical procedures on left lower and right lower limb

3. Study Procedure

Prior to the commencement of the experiment, this study was approved by the Institutional Review Board of Dong-Eui University (IRB No. DIRB-201601-HR-R-004) to ensure compliance with the Bioethics and Safety Act and to prevent any infringement on the dignity and safety of participants. The purpose of the study, experimental procedures, potential risks, and benefits were fully explained to all participants and their parents or legal guardians. Written informed consent for voluntary participation was obtained from all participants and their guardians. Participants were informed that they could withdraw from the study at any time during the research process without any personal disadvantage.

Participants with spastic cerebral palsy were assigned to one of two groups according to the type of orthopedic surgical technique received: (1) the muscle lengthening group, in which spastic lower-limb muscles were surgically elongated, and (2) the combined surgery group, in which muscle lengthening was performed along with osteotomies of the femur, tibia, and ankle bones for realignment. In the muscle lengthening group, immobilization with a cast was applied for up to 45 days, whereas in the combined surgery group, casting lasted for more than 45 days. Long-leg or short-leg casts were used to support the operated joints and restrict movement.

Following cast removal, a neurodevelopmental treatment program was implemented for 40 minutes per session, over 8 weeks, to ensure that children could adapt to therapy without pain. This program included passive range of motion exercises for the operated lower limbs, muscle stretching, strengthening exercises, sit-to-stand practice, and assisted standing and walking on a support surface with therapist assistance.

Body weight-supported treadmill training commenced approximately 8 weeks after NDT, upon approval from the attending physician confirming that participants could perform independent standing and walking. The body weight-supported treadmill training was conducted for 10 minutes per session, three times per week, for a total of 10 weeks. After completing NDT, all participants in both groups performed gait training on a treadmill (Sky Life 5100, Daehan Running Machine, Korea) using a body weight support harness system. To maximize plantar sensory input during the gait cycle, participants did not wear ankle–foot orthoses (AFOs) or shoes during training; instead, they wore thin, non-slip socks. The initial body weight support was set at 30 % and gradually reduced over the course of training. Treadmill inclination was maintained at 0 %, and speed was initially set between 0.1 and 0.8 km/h to promote a natural gait pattern, with adjustments made according to each child’s abilities. By the end of the 10-week program, speed was increased up to 1.3 ㎞/h.

4. Measurement tools and methods

1) Balance abilities

The trunk control ability of children with spastic cerebral palsy was assessed using the Korean version of the trunk control measurement scale (K-TCMS) (Ko & Jung, 2017). This assessment tool requires no specialized equipment other than a chair, small objects (e.g., balls, blocks), and a stopwatch, and can objectively evaluate functional changes in trunk control in children with cerebral palsy aged 5 years and older within approximately 15~20 minutes (Heyrman et al., 2014; Meyns et al., 2017; Sæther et al., 2015).

The K-TCMS consists of three subscales with a total of 15 items: static sitting balance (5 items, 20 scores), dynamic sitting balance (7 items, 28 scores), and dynamic reaching (3 items, 10 scores), with a maximum total score of 58 scores. Static sitting balance evaluates the ability to maintain postural alignment and stability while sitting upright on a chair or mat without external support. Dynamic sitting balance assesses the ability to maintain balance during voluntary tasks such as weight shifting, trunk tilting, and reaching. Dynamic reaching evaluates the ability to selectively rotate and control the trunk toward one side while the opposite side remains fixed.

Each item is scored from 0 (unable to perform), to 2 (partial performance or loss of balance), or 3 (accurate performance with balance maintained). Higher scores indicate better trunk control ability. The K-TCMS has demonstrated excellent inter-rater reliability (ICC= 0.94~0.98) in evaluating trunk control in children with cerebral palsy, making it a valuable tool for both clinical and research settings (Heyrman et al., 2011).

2) Activities of daily living

The performance of activities of daily living in children with cerebral palsy was assessed using the functional independence measure for children (WeeFIM). The WeeFIM is an adaptation of the functional independence measure (FIM) for adults, modified and developed to reflect developmental stages in children, and is used to assess the level of functional independence and daily living performance in children aged 6 months to 7 years, or in children with disabilities whose developmental age is below 7 years (Msall et al., 1994). This tool focuses on disability rather than impairment, evaluating the degree of independence in daily activities. It consists of three domains —self-care, mobility, and cognition—divided into six subdomains and a total of 18 items.

Self-care (8 items) includes eating, grooming, bathing, dressing (upper and lower body), and bowel/bladder management. Mobility (5 items) assesses transfers between bed, chair, and wheelchair; transfer to the toilet; walking or wheelchair mobility; and stair climbing. Cognition (5 items) evaluates comprehension, expression, social interaction, problem-solving, and memory.

Each item is scored on a 7 points scale: complete independence or modified independence (points 6~7), need for assistance (points 3~5), or complete dependence (points 1~2). The total score ranges from 18 to 126, with higher scores indicating greater functional independence. The WeeFIM demonstrates excellent intra- and inter-rater reliability (ICC>0.95) and shows significant correlations with GMFCS levels and gross motor function changes, making it a standardized tool for quantitatively assessing daily living performance and the degree of dependence or independence in children (Ottenbacher et al., 2000).

5. Data analysis

Data collected in this study were analyzed using SPSS 28.0 for Windows (IBM Corp., USA), with the significance level (α) set at .05. Descriptive statistics were calculated to summarize the participants’ general and medical characteristics. The normality of the measured variables was verified using the Shapiro–Wilk test, after which non-parametric tests were conducted.

Within-group comparisons of pre-training and post-10-week training changes in balance and activities of daily living for the muscle lengthening group and the combined surgery group were analyzed using the Wilcoxon signed-rank test. Differences in change scores between the two groups were compared using the Mann–Whitney test.

Ⅲ. Results

1. Balance abilities

Within-group changes in balance ability before and after 10 weeks of training in the muscle lengthening group and the combined surgery group are presented in Table 3. In both groups, overall balance ability significantly increased after 10 weeks of training compared to baseline (p<.05). When analyzed by subscale, the muscle lengthening group showed significant improvements in both static sitting balance and dynamic sitting balance, whereas the combined surgery group showed a significant improvement only in static sitting balance.

Table 3. Within-group analysis of balance ability before and after 10 weeks of training in the muscle lengthening and combined surgery group (unit: scores)

Between-group differences in change scores for balance ability are presented in Table 4. Significant differences were found between the two groups in dynamic sitting balance, dynamic reaching, and overall balance ability (p<.05).

Table 4. Between-group comparison of change differences in balance ability before and after training in the muscle lengthening and combined surgery group (unit: scores)

2. Activities of daily living

Within-group changes in activities of daily living before and after 10 weeks of training in the muscle lengthening group and the combined surgery group are presented in Table 5. In both groups, activities of daily living scores significantly increased after 10 weeks of training compared to baseline (p<.05). When analyzed by subscale, the muscle lengthening group showed significant improvements in the self-care and mobility domains, whereas the combined surgery group showed a significant improvement only in the mobility domain.

Table 5. Within-group analysis of activities of daily living before and after 10 weeks of training in the muscle lengthening and combined surgery group (unit: scores)

Between-group differences in change scores for activities of daily living are presented in Table 6. Significant differences were found between the two groups in the self-care domain and in overall activities of daily living performance (p<.05).

Table 6. Between-group comparison of change differences in activities of daily living before and after training in the muscle lengthening and combined surgery group (unit: scores)

Ⅳ. Discussion

This study examined the effects of body weight-supported treadmill training on balance ability and activities of daily living in children with spastic cerebral palsy who had undergone lower-limb orthopedic surgery, and compared training effects between the muscle lengthening group and the combined surgery group. The findings indicated that both groups showed significant improvements in balance and activities of daily living after 10 weeks of body weight-supported treadmill training. However, differences emerged between groups in domain-specific changes from baseline to post-training, as well as in change scores, depending on the surgical technique.

In the muscle lengthening group, significant improvements were observed in both static sitting balance and dynamic sitting balance after training, with greater change scores than the combined surgery group in dynamic sitting balance, dynamic reaching, and overall balance. These results are consistent with Grecco et al. (2013), who reported that treadmill gait training was superior to overground gait training in enhancing functional balance and lateral postural control. Particularly, repetitive and rhythmic lower-limb movements during treadmill training may enhance trunk stability and balance strategies, and activate the central pattern generator at the spinal cord level, thereby facilitating motor function recovery (Barbeau, 2003; Dimitrijevic et al., 1998). Additionally, significant improvements in the self-care and mobility domains, as well as in overall activities of daily living, may be attributed to the shorter immobilization period after surgery, allowing for earlier coordination training of the upper and lower limbs and trunk stabilization. These findings align with previous studies by Grecco et al. (2013), Johnston et al. (2011), and Cherng et al. (2007), which reported that body weight-supported treadmill training contributes not only to improvements in gross motor function and mobility but also to enhanced overall activities of daily living performance.

In contrast, the combined surgery group showed increases in dynamic sitting balance and dynamic reaching after 10 weeks, but these changes were not statistically significant; significant improvement was observed only in static sitting balance. Such limited changes may be due to the longer immobilization period following muscle lengthening combined with osteotomy, as well as proximal muscle weakness, which together necessitate a longer rehabilitation period before substantial improvements in gait posture and functional mobility can be achieved (Rodda et al., 2006; Stout et al., 2008). Regarding activities of daily living, significant improvement was observed only in the mobility domain, while changes in self-care were limited. This may be explained by the focus of early rehabilitation on restoring functional movements and mobility after an extended immobilization period. Nevertheless, the significant improvement in mobility after 10 weeks suggests that body weight-supported treadmill training, by comprehensively enhancing gait speed, stride length, and balance strategies, can positively influence daily mobility-related activities in children with cerebral palsy who have limited or no ambulatory ability (Cherng et al., 2007; Schindl et al., 2000; Willoughby et al., 2010).

Children with spastic cerebral palsy experience differences in immobilization periods after lower-limb orthopedic surgery depending on the surgical technique and extent of intervention. According to Novacheck and Gage (2007), children with cerebral palsy often present with multilevel and multiplanar deformities, for which single-event multilevel surgery-performing multiple procedures under a single anesthesia-is commonly applied. Although single-event multilevel surgery reduces the number of hospital admissions and facilitates a consistent rehabilitation plan, when both tendon lengthening and grafting, along with corrective osteotomy, are performed, an immobilization period of approximately 4~12 weeks is required. During this time, children are unable to engage in physical activity of sufficient intensity to develop cardiopulmonary endurance and muscle strength, leading to deconditioning and progressive decline in functional mobility (Dimitrijevic et al., 1998; Palisano et al., 1997). Such changes may negatively affect subsequent balance and activities of daily living performance.

In contrast, when only muscle lengthening is performed, the required immobilization period is relatively short-approximately 3~6 weeks-allowing for earlier weight-bearing and training. A shorter immobilization period facilitates earlier initiation of treadmill training, which may provide opportunities to acquire efficient motor control patterns based on the newly realigned biomechanical structure following surgery.

Significant differences were also observed between the muscle lengthening group and the combined surgery group in the changes in balance ability and activities of daily living performance before and after body weight–supported treadmill training. Specifically, significant differences were found in dynamic sitting balance, dynamic reaching, and overall balance ability for balance outcomes, as well as in self-care and overall performance for activities of daily living. These findings suggest that differences in surgical techniques for children with spastic cerebral palsy may influence the rate and extent of postoperative recovery of physical function and mobility.

In contrast, the study by Grecco et al. (2013) reported significant improvements in gross motor function (GMFM-88) and 6-minute walk distance after 12 weeks of treadmill training in both the soft-tissue surgery group and the combined soft-tissue and bone surgery group, but a significant difference in change scores between groups was found only for diastolic blood pressure. Although that study did not assess balance ability or activities of daily living performance, the observed differences between the two studies may be related to variations in intervention duration, weekly training frequency, and specific implementation methods. Whereas the previous study applied treadmill training once a week for 12 weeks, the present study implemented a similar total intervention period of 10 weeks but with three sessions per week. The higher weekly intervention frequency substantially increased the cumulative training volume, which may have contributed to detecting differences in recovery between surgical techniques not only in walking ability but also in more complex functional domains such as balance ability and activities of daily living performance.

In summary, while the previous study did not demonstrate clear differences in training effects according to orthopedic surgical technique, the present study identified significant intergroup differences in specific domains of balance ability and activities of daily living performance. These results highlight the need for tailored treadmill training programs based on surgical technique in the early postoperative rehabilitation phase, not only to improve walking ability but also to enhance balance and activities of daily living.

These findings suggest that the surgical techniques and immobilization periods for the lower limbs in children with spastic cerebral palsy may influence the rate and extent of postoperative rehabilitation progress, and in particular, highlight the need for early rehabilitation interventions following muscle lengthening surgery. In particular, the findings highlight the importance of early rehabilitation interventions following muscle lengthening. Body weight-supported treadmill training, as a task-specific approach, enables children to perform gait cycles in a controlled environment (Macko et al., 2001; Visintin et al., 1998), while body weight support via a harness promotes biomechanical alignment, minimizes compensatory movements, and allows for repeated practice without fatigue (Begnoche & Piett, 2007). Furthermore, repetitive walking training on a treadmill can activate the spinal central pattern generator, strengthening intermuscular coordination required for balance and gait (Dimitrijevic et al., 1998). Therefore, body weight-supported treadmill training appears to be an effective rehabilitation strategy for improving both balance and activities of daily living performance in children with spastic cerebral palsy, regardless of the surgical technique.

This study has several limitations. First, the small sample size and heterogeneity in participants’ age, functional level, and surgical sites and extent limit the generalizability of the findings. Second, only the effects of 10 weeks of treadmill training were analyzed, without follow-up to determine the long-term sustainability of the effects. Third, the assessment tools for balance and activities of daily living may not have fully captured all functional changes. Fourth, extraneous factors such as home activity levels and participation in other rehabilitation therapies were not fully controlled.

Clinically, it is recommended that body weight-supported treadmill training be implemented as early as possible after lower-limb surgery in children with spastic cerebral palsy. In particular, to improve self-care function, reducing the immobilization period and incorporating integrated upperand lower-limb training may be beneficial. Future studies should include long-term follow-up to verify the persistence of these effects and develop optimized training protocols according to surgical type and rehabilitation initiation timing.

Ⅴ. Conclusion

This study investigated the effects of body weight-supported treadmill training on balance ability and performance of activities of daily living in children with spastic cerebral palsy who had undergone lower-limb orthopedic surgery, and compared training outcomes between the muscle lengthening group and the combined surgery group. The results showed that, in both surgical groups, balance ability and activities of daily living improved after 10 weeks of body weight-supported treadmill training; however, differences between groups were observed in domain-specific improvements and change scores.

In the muscle lengthening group, significant improvements were found in total balance score, static sitting balance, and dynamic sitting balance, as well as in both self-care and mobility domains of activities of daily living. In contrast, the combined surgery group demonstrated significant improvements only in total balance score and static sitting balance, and, in terms of activities of daily living, improvement was observed only in the mobility domain. Between-group comparisons of change scores revealed that the muscle lengthening group achieved significantly greater gains than the combined surgery group in dynamic sitting balance, dynamic reaching, total balance ability, self-care, and total activities of daily living performance.

These findings suggest that body weight-supported treadmill training is an effective rehabilitation strategy for functional recovery in children with spastic cerebral palsy regardless of the orthopedic surgical technique. Notably, the greater functional gains observed in the muscle lengthening group, which had a shorter immobilization period, underscore the importance of early rehabilitation intervention. Clinically, it is recommended that body weight-supported treadmill training be initiated as early as possible after surgery in children with spastic cerebral palsy. Future research should include long-term follow-up to verify the sustainability of training effects and to develop optimized protocols tailored to surgical technique and timing of rehabilitation initiation.