Purpose: The aim of this study is to assess the short- and midterm evolution of self-care and functional mobility after multilevel surgery in children and adolescents with spastic diplegic cerebral palsy and to identify which factors could have an impact on these outcomes.

Methods: Thirty-four participants were included. All participants will be evaluated before surgery, at 9 weeks, 6,12,18, 24, 36 and 60 months. Self-care was assessed with the Pediatric Evaluation of Disability Inventory-NL (PEDI-NL). The Mobility Questionnaire47 (MobQues47) and Functional Mobility Scale (FMS) were used to measure functional mobility. Interactions between CP, personal and environmental characteristics and evolution in time were assessed.

1. Introduction Cerebral palsy (CP) is the most common physical disability with a prevalence between two and three per 1000 living births. Cerebral palsy had been defined as a group of permanent disorders of the development of movement and posture, causing activity limitations that are contributed to non-progressive disturbances that occurred in the developing fetal and infant brain. The motor disorders are often accompanied by disturbances of sensation, perception, cognition, communication and behavior, by epilepsy and by secondary musculoskeletal problems. Cerebral palsy can have an impact on the body function and on the performance of daily life activities and as such may affect the child's independence, participation and quality of life.

The impact of cerebral palsy on individuals varies widely. The SCPE describes a hierarchical classification tree of cerebral palsy subtypes: spastic CP, dyskinetic CP and ataxic CP. Spastic CP is the most common type and is seen in 85% of the children with CP. The Gross Motor Function Classification System (GMFCS) classifies children and adolescents with cerebral palsy in five levels on the basis of their functional abilities in sitting and walking. Further subdivision is made according to the topographical distribution i.e. hemiplegia, diplegia and quadriplegia. Howard et al. reported that in a group of 323 children with spastic cerebral palsy 35 % of children had hemiplegia, 28 % diplegia and 37% quadriplegia. In their study the GMFCS levels of spastic diplegic cerebral palsy were 33% with GMFCS I, 33 % GMFCS II, 28% GMFCS III and 5% GMFCS IV. This means that nearly all spastic diplegic patients have the ability to walk with or without assistive devices.

A multidisciplinary follow-up is necessary during growth of the child with CP. A good knowledge of normal developmental milestones and natural history of children with CP is important to detect and prevent early problematic situations. In normal development the period of early childhood is characterized by rapid development of locomotor skills as walking, running and stair climbing. Typically developing children learn the skill of walking between the ages of eight and eighteen months. Children further learn to talk, start potty training and start to develop their independence in self-care skills. Achieving independence in dressing may take up to four years. Tying shoelaces and completing all clothing fasteners is achieved at age of six years. During this time, parents gradually perform fewer of the tasks, and encourage their children to do more, with the ultimate goal of independence.

In comparison with typically developing children, a child with spastic diplegic CP will show delay in all milestones but will generally stand at eighteen months and most will walk independently by four years. In the self-care domain, over half of the children with cerebral palsy needed help or supervision in the areas of grooming, bathing, dressing, and toileting. The gross motor function and function of self-care skills is steadily improving. At the age of nine years most children with spastic diplegic CP reached their maximum functional potential. Öhrvall et al. described that many children with CP achieve independence but at a later age than typically developing children. They reported that children with high functioning levels in GMFCS and in the Manual Ability Classification System (MACS) could achieve good functional performance for self-care and mobility at the age of 12 years. For children with GMFCS and MACS level III and more only minor development of functional skills is seen with age, although task-orientated and goal-directed therapy can improve their functioning.

Despite the improvement in self-care with age, several studies reported that the gait pattern in children with CP is deteriorating. Due to increased muscle tone and weakness children with spastic diplegic CP walk with hip and knee flexion, inward rotation and toe walking, hereby secondary problems like muscle contractures and bony deformities slowly arise. Further during the adolescents year's rapid growth and increase of body weight can lead to worsening deformities and changes in ratio of body mass to strength. Decrease of this ratio has a negative effect on the gait pattern.

Orthopedic surgery aims to counteract the effect of natural history by preventing the deterioration and as such maintaining function and keeping the child ambulant. Instead of performing several single level surgeries during childhood - the birthday syndrome approach - the modern approach aims to correct both muscle imbalance and bone deformity at the same time. The latter approach is called single event multilevel surgery (SEMLS) and ensures only one admission to the hospital with one rehabilitation period. SEMLS is not a uniform procedure but is tailored to the child's needs by lengthening shortened muscle-tendon units and realigning bony levers. In the University Hospital of Pellenberg, botulinum toxin is frequently applied simultaneously to reduce spasticity. Botox treatment and surgical treatment must be seen as complementary rather than exclusive. They both deliver benefits to a more normal alignment and make optimal rehabilitation possible. In addition successful outcome after multilevel surgery requires intensive training for at least one year following surgery. Important rehabilitation goals are improvement of the range of motion, strength, balance and function.

Several studies have investigated the effects of SEMLS. Two studies identified the loss of muscle strength post SEMLS. Seniorou et al. reported that muscle strength did not reach pre-operative status one year after SEMLS. It has been shown that multilevel surgery corrects musculoskeletal pathology and significantly improves the gait pattern. In the study of Thomason et al. these results were maintained at five years after surgery. However an important goal for children and parents is not only to achieve a better gait pattern but also to obtained an improved functionality in daily life. Mc Ginley et al. and Graham et al. stressed the importance for more longterm studies with multidimensional outcome measures in all domains of the International Classification of Functioning, Disability and Health (ICF).

There is a lack of studies focusing on the impact of SEMLS on activity level like self-care and functional mobility. Still information on these outcomes is very important for children and parents before undertaken this intervention. After SEMLS the intensive rehabilitation period requires high physical and mental demands and the long lasting rehabilitation process could be strenuous for children and parents. Insufficient information about the post-surgery period could lead to frustration of the parents and children.

A few longitudinal studies measured functional mobility in daily life activities after SEMLS using the Functional Mobility Scale (FMS). Harvey et al.reported for a group of 66 children with spastic diplegic CP a deterioration at three and six months post-surgery, followed by improvement back to baseline status at one year and further improvement at two years post-surgery. Another study in nine children with spastic diplegic CP showed one year after SEMLS no differences in the FMS. Children in this study underwent also bony foot surgery as part of SEMLS. In the follow-up study of Thomason et al. nearly half of the children had improved on the distance of 50 and 500 m five years post-surgery. In this study in 19 children with spastic diplegic CP no child deteriorated on the three distances of the FMS.

Only two studies reported effects of SEMLS in the domain of self-care skills. Buckon et al. compared the evolution of self-care after selective dorsal rhizotomy (SDR) and SEMLS using the PEDI in 25 children with spastic diplegia (18 SDR, 7 SEMLS). The SDR group showed significant gains for self-care skills at six months, one year and two years. The SEMLS group demonstrated no gains six months post-surgery. However at one and two year post SEMLS a significant increase in self-care skills was found. For the caregiver assistance only at two years post-surgery there was a significant decrease in the amount of assistance. Another study of Gorton et al. in 75 children with spastic CP (GMFCS I to III) reported no significant gain in scores on the Pediatric Functional Independence Measure (WeeFIM) one year post SEMLS.

Also some studies used Quality of life (QOL) measures after SEMLS. Two studies reported improvement of functional well-being one or two years after SEMLS. However the psychosocial and emotional wellbeing remained unchanged. Weak relationship between function and psychosocial domains of QOL was previously reported by Shelly et al. The study of Himpens et al. using the CP QOL showed that children with CP after SEMLS reported a higher quality of life compared to their parents reporting.

In summary, only a paucity of studies have been set up to study the effects on outcomes such as gross motor functional skills, activities of daily living functional skills and quality of life. Nevertheless it is necessary to examine the patient not only in gait laboratories but also in the context of daily life. Previous studies had only a short follow-up. There were based on a small sample size or had children with different types of CP . Further study is clearly needed to provide more insights in the short- mid- and longterm evolution of self-care and functional mobility following SEMLS.

Furthermore, knowledge of the factors influencing this evolution is of particular interest. Several CP related, personal and environmental characteristics may determine the evolution following surgery. The understanding of the associations between functional outcomes after SEMLS and potential influencing factors will aid to set realistic expectations and appropriate treatment plans after SEMLS. However, information on influencing factors on outcome of SEMLS is very limited. Svehlik et al. found better results following SEMLS for older children than younger children. The authors hypothesized that the finished growth spurt and probable better cooperation in therapy for the older children may lead to better outcomes. As Hoffinger indicated these results should be interpreted cautiously. Both groups in the retrospective study of Svehlik et al. are not the same. The older children had a poorer ambulation caused by primarily bone deformities, while the younger children had muscle contractures and muscle activation problems. Another study of Zwick et al. suggests that girls have better outcomes than boys. To date, only limited personal characteristics like age and gender were investigated as influencing factors, other possible interfering factors like GMFCS en MACS level, number of surgery and initial level on self-care and functional mobility have to be taken into account.

The aims of this study were to investigate the evolution in self-care and functional mobility at different time points over the first year following SEMLS and to assess if determinants could be identified that have an influence on these time trends.

Methods:

This prospective longitudinal study has a 5 year follow-up period. This study reports the short-term, midterm and longterm outcomes, i.e. at 2, 6, 12, 24, 36 and 60 months after SEMLS. Outcome measures were collected before surgery (time interval between one month to one day before surgery; T1) and at defined intervals after surgery, at 9 weeks (T2), 6 months (T3), 1 year (T4), 18 months (T5), 2 years (T6), 3 years (T7) and 5 years (T8). At this moment participants completed follow-up at 2 years.

All 34 participants were followed by the CP-reference center of the University Hospital of Pellenberg. The surgical recommendation was based to the participants' needs and determined by a comprehensive evaluation, including a standardized physical examination, radiographic evaluation and instrumental gait analysis.

All children and adolescents were hospitalized for one week after surgery in the University Hospital of Pellenberg. One week post-surgery they were discharged wearing plaster casts below-the-knee and removable knee braces. Participants received physiotherapy at home (five times a week) which consisted of passive joint mobilization. Four weeks after surgery participants were hospitalized again for rehabilitation at the University Hospital of Pellenberg or at the rehabilitation center 'Pulderbos' at Zandhoven. Rehabilitation comprised intensive individualized physiotherapy including an exercise programme of two hours per day, two hours positioning (standing table and specific stretch positions in prone and supine). The exercise programme consists of strength training and gait reeducation. Additionally, occupational therapy was provided if necessary (three times a week, 30-45 minutes) and focused on training upper limb function, transfers and activities of daily living (eating, washing, grooming,…). The rehabilitation period (hospital Pellenberg or rehab center Pulderbos) ranged from six to twelve weeks. Children and adolescents were discharged from the rehabilitation unit when independent walking with kaye-walker was possible. At home, rehabilitation was continued with the private physiotherapist with a frequency of five times a week up to six months post-surgery. At six months the frequency was individually adopted according to their needs. The children attending special education school had physiotherapy at school combined with private physiotherapy. The rehabilitation programme was similar in the two involved centres.

The Pediatric Evaluation of Disability Inventory (PEDI), Mobility Questionnaire47 (MobQues47), Functional Mobility Scale (FMS) and Manual Muscle Testing (MMT) were measured before surgery and after surgery at nine weeks, six months and one year. The CP QOl Child was measured before SEMLS and at one, three and five years following surgery.

All baseline assessments were conducted in the hospital of Pellenberg, assessment at nine weeks after surgery was performed at the rehabilitation unit, i.e. Pellenberg or Pulderbos. The following assessments took place during the follow-up consultations in the University Hospital of Pellenberg. The same assessor (senior occupational therapist) evaluated all participants, supported by two junior physiotherapists. Clinical assessments were practiced jointly in order to standardize assessment procedures.

Age, gender, intelligence and type of school, the level of Gross Motor Function Classification System (GMFCS) and Manual Ability Classification System (MACS) were collected before surgery. Also the surgical procedures and botulinum injections were documented.

Inclusion Criteria:

• diagnosis of diplegic CP (Rosenbaum et al., 2007);
• GMFCS levels I, II, and III;
• aged between 6 and 25 years;
• bilateral surgery.

Exclusion Criteria:

• other diagnosis than cerebral palsy;
• severe mental retardation (IQ < 50).

All consecutive children and adolescents with spastic diplegic CP who underwent multilevel surgery in the University Hospital of Pellenberg were screened for entry in the study between December 2012 and August 2014. SEMLS was defined as orthopedic surgery (soft-tissue or bony surgical procedures, combined or not with botulinum toxin injection) at two or more anatomical levels during one operative procedure, requiring only one hospital admission and rehabilitation period.