Aims. The migration percentage (MP) is one criterion used for surgery in dislocated or displaced hips in children with cerebral palsy (CP). The MP at which a displaced hip can no longer return to normal is unclear. The aim of this paper was to identify the point of no return of the MP through a large population-based study. Methods. All children registered on the Cerebral Palsy Integrated Pathway Scotland surveillance programme undergo regular pelvic radiographs. Any child who had a MP measuring over 35% since the programme’s inception in 2013, in at least one hip and at one timepoint, was identified. The national radiography database was then interrogated to identify all pelvic radiographs for each of these children from birth through to the date of analysis. A minimum of a further two available radiographs following the initial measurement of MP ≥ 35% was required for inclusion. Results. A total of 239 children (346 hips) were identified as suitable for analysis at a mean of 6.5 years (2.0 to 14.8) follow-up. In all, 1,485 radiographs taken both prior to and after a hip had a MP ≥ 35% were examined and the MP measured to identify any progression of displacement. Interrogation of the data identified that hips with a MP up to 46% returned to a MP below 40% without intervention, and all hips with a MP equal to or greater than 46% displaced further and the MP did not return to the normal range. Statistical analysis showed the result to be 98% specific with this degree of certainty that hips reaching a MP ≥ 46% would not spontaneously regress. Conclusion. These findings are clinically relevant in showing that it may be reasonable to continue to monitor hips with a MP not exceeding 46%. This threshold will also guide referral for further management of a displacing hip. Cite this article: Bone Joint J 2021;103-B(2):411–414

Purpose. The incidence of hip displacement in children with cerebral palsy is approximately 30% in large population based studies. The purpose of this study was to report the long-term effect of hip surgery on the incidence of hip displacement using a newly validated Cerebral Palsy (CP) hip classification. Method. Retrospectively, a sub-group of 100 children who underwent surgery for hip displacement were identified from a large-population based cohort of children born with CP between January 1990 and December 1992. These children were followed to skeletal maturity and closure of their tri-radiate cartilage. All patients returned at maturity for clinical and radiographic examination, while caregivers completed the disease specific quality of life assessments. Patients were grouped according to motor disorder, topographical distribution and GMFCS. Radiographs were independently graded according to CP hip classification scheme to ensure reliability. Surgical Failures were defined as CP Grade > IV. Results. Ninety-seven children and 194 hips were available for final review. According to GMFCS, greater than half the children were GMFCS IV and V (67/94, 67%), 12 were II and 18 were III. Fifteen hips were dislocated or had salvage surgery for dislocation (15/194, 7.7%) at time of skeletal maturity. The majority of hips were graded Grade II and III (149/194, 76.8%). A total of 39 (39/194, 20%) hips were classified as surgical failure with 95% (37/39) hips occurring in GMFCS IV and V children. Conclusion. Using the CP hip classification scheme, the natural history and outcome of 100 children with CP at skeletal maturity have been described. Despite hip surveillance and surgical intervention GMFCS IV and V children are at the greatest risk for surgical failure at skeletal maturity. In this study, the majority of failures were associated with either no hip surveillance and/or index surgery at a non-specialist centre. In contrast, hip surveillance and index surgery at a specialist tertiary centre was associated with a very high probability of a successful outcome. This is the first population based cohort study of children with cerebral palsy followed from index surgery to skeletal maturity for hip displacement. Surgical success rates for the treatment of hip displacement in children with cerebral palsy have not previously been reported. This information will aid surgeons in the treatment of hip displacement in children with cerebral palsy

There is much debate about the nature and extent of deformities in the proximal femur in children with cerebral palsy. Most authorities accept that increased femoral anteversion is common, but its incidence, severity and clinical significance are less clear. Coxa valga is more controversial and many authorities state that it is a radiological artefact rather than a true deformity. We measured femoral anteversion clinically and the neck-shaft angle radiologically in 292 children with cerebral palsy. This represented 78% of a large, population-based cohort of children with cerebral palsy which included all motor types, topographical distributions and functional levels as determined by the gross motor function classification system. The mean femoral neck anteversion was 36.5° (11° to 67.5°) and the mean neck-shaft angle 147.5° (130° to 178°). These were both increased compared with values in normally developing children. The mean femoral neck anteversion was 30.4° (11° to 50°) at gross motor function classification system level I, 35.5° (8° to 65°) at level II and then plateaued at approximately 40.0° (25° to 67.5°) at levels III, IV and V. The mean neck-shaft angle increased in a step-wise manner from 135.9° (130° to 145°) at gross motor function classification system level I to 163.0° (151° to 178°) at level V. The migration percentage increased in a similar pattern and was closely related to femoral deformity. Based on these findings we believe that displacement of the hip in patients with cerebral palsy can be explained mainly by the abnormal shape of the proximal femur, as a result of delayed walking, limited walking or inability to walk. This has clinical implications for the management of hip displacement in children with cerebral palsy

In 1994, a register for cerebral palsy and a health-care programme were started in southern Sweden with the aim of preventing dislocation of the hip in children with cerebral palsy. It involved all children with cerebral palsy born in 1992 or later. None of the 206 affected children born between 1992 and 1997 has developed a dislocation following the introduction of the prevention programme. Another 48 children moved into the area and none developed any further dislocation. Of the 251 children with cerebral palsy, aged between five and 11 years, living in the area on January 1, 2003, only two had a dislocated hip. One boy had moved into the area at age of nine with a dislocation and a girl whose parents chose not to participate in the programme developed bilateral dislocation. One boy, whose condition was considered to be too poor for preventative surgery, developed a painful dislocation of the hip at the age of five years and died three years later. Eight of 103 children in a control group, consisting of all children with cerebral palsy living in the area between 1994 and 2002, and born between 1990 and 1991, developed a dislocation of the hip before the age of six years. The decreased incidence of dislocation after the introduction of the prevention programme was significant (p < 0.001). Dislocation of the hip in cerebral palsy remains a serious problem, and prevention is important. Our screening programme and early intervention when lateral displacement of the femoral head was detected appear to be successful

Aims. The Uppföljningsprogram för cerebral pares (CPUP) Hip Score distinguishes between children with cerebral palsy (CP) at different levels of risk for displacement of the hip. The score was constructed using data from Swedish children with CP, but has not been confirmed in any other population. The aim of this study was to determine the calibration and discriminatory accuracy of this score in children with CP in Scotland. Methods. This was a total population-based study of children registered with the Cerebral Palsy Integrated Pathway Scotland. Displacement of the hip was defined as a migration percentage (MP) of > 40%. Inclusion criteria were children in Gross Motor Function Classification System (GMFCS) levels III to V. The calibration slope was estimated and Kaplan-Meier curves produced for five strata of CPUP scores to compare the observed with the predicted risk of displacement of the hip at five years. For discriminatory accuracy, the time-dependent area under the receiver operating characteristic curve (AUC) was estimated. In order to analyze differences in the performance of the score between cohorts, score weights, and subsequently the AUC, were re-estimated using the variables of the original score: the child’s age at the first examination, GMFCS level, head shaft angle, and MP of the worst hip in a logistic regression with imputation of outcomes for those with incomplete follow-up. Results. The discriminatory accuracy of the score in the new population of 367 children was high (AUC 0.78 (95% confidence interval (CI) 0.71 to 0.86)). The calibration of the score was insufficient (slope 0.48 (95% CI 0.31 to 0.65)), and the absolute risks of displacement of the hip in this population were overestimated. The AUC increased with re-estimated weights (0.85 (95% CI 0.79 to 0.91)). Conclusion. The CPUP Hip Score had a high ability to discriminate between children at different levels of risk for displacement of the hip. The score overestimated the absolute risks of displacement in this population, which may have resulted from differences in the way children were initially registered in the two programmes. The results are promising, but the score weights may need re-estimation before its clinical application in Scotland. Cite this article: Bone Joint J 2022;104-B(5):640–644

Aims. The purpose of this study was to compare the prevalence of hip displacement and dislocation in a total population of children with cerebral palsy (CP) in Scotland before and after the initiation of a hip surveillance programme. Patients. A total of 2,155 children with CP are registered in the Cerebral Palsy Integrated Pathway Scotland (CPIPS) surveillance programme, which began in 2013. Physical examination and hip radiological data are collected according to nationally agreed protocols. Methods. Age, Gross Motor Function Classification System (GMFCS) level, subtype of CP, migration percentage (MP), and details of hip surgery were analyzed for all children aged between two and 16 years taken from a time of census in March 2019 and compared to the same data from the initial registration of children in the CPIPS. Displacement of the hip was defined as a MP of between 40% and 99%, and dislocation as a MP of 100%. Results. A total of 1,646 children were available for analysis at the time of the census and 1,171 at their first registration in CPIPS. The distribution of age, sex, and GMFCS levels were similar in the two groups. The prevalence of displacement and dislocation of the hip before surveillance began were 10% (117/1,171) and 2.5% (29/1,171) respectively, and at the time of the census were 4.5% (74/1,646) and 1.3% (21/1,646), respectively. Dislocation was only seen in GMFCS levels IV and V and displacement seen in 90.5% (67/74) of these levels and 9.5% (7/74) in levels I to III. In total, 138 children had undergone hip surgery during the study period. The hip redisplaced after the initial surgery in 15 children; seven of these had undergone a second procedure and at the time of the census the hips in all seven had a MP < 40. Conclusion. Hip surveillance appears to be effective and has reduced the prevalence of hip displacement by over half and dislocation almost by half in these children. Cite this article: Bone Joint J 2020;102-B(3):383–387

We have tested the reliability of a recently reported classification system of hip morphology in adolescents with cerebral palsy in whom the triradiate cartilage was closed. The classification is a six-grade ordinal scale, based on the measurement of the migration percentage and an assessment of Shenton’s arch, deformity of the femoral head, acetabular deformity and pelvic obliquity. Four paediatric orthopaedic surgeons and four physiotherapists received training in the use of the classification which they applied to the assessment of 42 hip radiographs, read on two separate occasions. The inter- and intra-observer reliability was assessed using the intraclass correlation coefficient and found to be excellent, with it ranging from 0.88 to 0.94. The classification in our study was shown to be valid (based on migration percentage), and reliable. As a result we believe that it can now be used in studies describing the natural history of hip displacement in cerebral palsy, in outcome studies and in communication between clinicians

In cerebral palsy, the site and severity of the brain lesion are directly linked to gross motor function and the development of musculoskeletal deformities. The relationship between walking ability and orthopaedic surgery in children with cerebral palsy is not fully understood. The development of new tools such as the Functional Assessment Questionnaire and the Functional Mobility Scale can be used to give new insights on the functional impact of multilevel surgery. These scales are most useful as part of systematic, long-term follow-up

1. Correction of equinus deformity in cerebral palsy either by elongation of the tendo calcaneus or by gastrocnemius recession gives satisfactory results without splintage or bracing after operation. 2. Gastrocnemius recession is the operation of choice in paraplegic spastic cerebral palsy, and wherever possible in tetraplegic cerebral palsy. In hemiplegia the whole of the triceps surae is usually involved, and elongation of the tendo calcaneus is almost always needed. 3. Correction at operation should aim to result in a mild degree of equinus deformity at the end of the growth period in hemiplegic spastic cerebral palsy. Over-enthusiastic gastrocnemius recession can lead to excessive weakness of the calf in some patients

Aims. Reimers migration percentage (MP) is a key measure to inform decision-making around the management of hip displacement in cerebral palsy (CP). The aim of this study is to assess validity and inter- and intra-rater reliability of a novel method of measuring MP using a smart phone app (HipScreen (HS) app). Methods. A total of 20 pelvis radiographs (40 hips) were used to measure MP by using the HS app. Measurements were performed by five different members of the multidisciplinary team, with varying levels of expertise in MP measurement. The same measurements were repeated two weeks later. A senior orthopaedic surgeon measured the MP on picture archiving and communication system (PACS) as the gold standard and repeated the measurements using HS app. Pearson’s correlation coefficient (r) was used to compare PACS measurements and all HS app measurements and assess validity. Intraclass correlation coefficient (ICC) was used to assess intra- and inter-rater reliability. Results. All HS app measurements (from 5 raters at week 0 and week 2 and PACS rater) showed highly significant correlation with the PACS measurements (p < 0.001). Pearson’s correlation coefficient (r) was constantly over 0.9, suggesting high validity. Correlation of all HS app measures from different raters to each other was significant with r > 0.874 and p < 0.001, which also confirms high validity. Both inter- and intra-rater reliability were excellent with ICC > 0.9. In a 95% confidence interval for repeated measurements, the deviation of each specific measurement was less than 4% MP for single measurer and 5% for different measurers. Conclusion. The HS app provides a valid method to measure hip MP in CP, with excellent inter- and intra-rater reliability across different medical and allied health specialties. This can be used in hip surveillance programmes by interdisciplinary measurers. Cite this article: Bone Jt Open 2023;4(5):363–369

Aims. Hip disease is common in children with cerebral palsy (CP) and can decrease quality of life and function. Surveillance programmes exist to improve outcomes by treating hip disease at an early stage using radiological surveillance. However, studies and surveillance programmes report different radiological outcomes, making it difficult to compare. We aimed to identify the most important radiological measurements and develop a core measurement set (CMS) for clinical practice, research, and surveillance programmes. Methods. A systematic review identified a list of measurements previously used in studies reporting radiological hip outcomes in children with CP. These measurements informed a two-round Delphi study, conducted among orthopaedic surgeons and specialist physiotherapists. Participants rated each measurement on a nine-point Likert scale (‘not important’ to ‘critically important’). A consensus meeting was held to finalize the CMS. Results. Overall, 14 distinct measurements were identified in the systematic review, with Reimer’s migration percentage being the most frequently reported. These measurements were presented over the two rounds of the Delphi process, along with two additional measurements that were suggested by participants. Ultimately, two measurements, Reimer’s migration percentage and femoral head-shaft angle, were included in the CMS. Conclusion. This use of a minimum standardized set of measurements has the potential to encourage uniformity across hip surveillance programmes, and may streamline the development of tools, such as artificial intelligence systems to automate the analysis in surveillance programmes. This core set should be the minimum requirement in clinical studies, allowing clinicians to add to this as needed, which will facilitate comparisons to be drawn between studies and future meta-analyses. Cite this article: Bone Jt Open 2023;4(11):825–831

Scoliosis is a common problem in cerebral palsy typified by rapid progression that often leads to large curve magnitudes even after skeletal maturity. The purpose of this study was to determine the relationship between curve progression and disease severity in cerebral palsy according to the Gross Motor Function Classification (GMFCS). This retrospective study reviewed 34 children with a known diagnosis of cerebral palsy who were scheduled for or have already had surgical stabilization for scoliosis. Two patients (6%) were classified as GMFCS level III, 13 (38%) as GMFCS level IV, and 19 (56%) as GMFCS level V. There were no patients in GMFCS levels I or II. Between the more severely involved children in GMFCS levels IV and V, there were no significant differences in curve magnitude at first presentation (means, 41.4 and 45.3 degrees, respectively; p=O.72), peak curve progression (28.2 degrees – interval 1.5 years, 31.4 degrees – interval 1. 75 years, respectively; p=O.35), or age at onset of peak curve progression (12.2 and 11.2 years, respectively). When adjusted for age at presentation, however, there was some indication of a difference in initial curve magnitude between GMFCS levels IV and V (least squares means, 35.7 and 49.2 degrees, respectively; p=O.10). The small number of patients in GMFCS level III precluded statistical analysis. In this study, the nature of scoliosis in cerebral palsy was found to be related to functional level. Once scoliosis has been diagnosed, children in the higher GMFCS levels have an increased risk of rapid and unpredictable curve progression

Purpose. The aim of this study was to identify if perioperative outcomes were different in patients with cerebral palsy undergoing unilateral or bilateral hip reconstruction. Method. All consecutive hip reconstructions for cerebral palsy performed by the senior author (FNT) within a tertiary-referral centre were identified between January 2012 and July 2016. Patients were stratified by age, gender, GMFCS and side of procedure. Length of surgery, pre- and post- operative haemoglobin, length of stay and immediate post-operative complications were measured. Results. 158 procedures were performed; 96 bilateral and 62 unilateral (37 left, 25 right). In bilateral procedures, operative time was 14 minutes longer (p= 0.07) and haemoglobin decrease was 1.85g/l greater (p= 0.34) with equivalent length of stay (average 6.4 days) and complication rate when compared to those undergoing unilateral procedures. Irrespective of procedure, those with a GMFCS level V had a longer length of stay (p< 0.05) and post-operative complication rate (p< 0.05) when compared to patients with GMFCS level IV. Conclusion. No significant differences were noted in the outcome measures when comparing unilateral and bilateral hip reconstructions in our group of patients with cerebral palsy. This suggests that concurrent prophylactic surgical management of the radiologically stable hip is a safe surgical option in this high-risk group of paediatric patients in an appropriate tertiary care setting with multidisciplinary team support

We studied prospectively the impact of a hip surveillance clinic on the management of spastic hip disease in children with cerebral palsy in a tertiary referral centre. Using a combination of primary clinical and secondary radiological screening we were able to detect spastic hip disease at an early stage in most children and to offer early surgical intervention. The principal effect on surgical practice was that more preventive surgery was carried out at a younger age and at a more appropriate stage of the disease. The need for reconstructive surgery has decreased and that for salvage surgery has been eliminated. Displacement of the hip in children with cerebral palsy meets specific criteria for a screening programme. We recommend that hip surveillance should become part of the routine management of children with cerebral palsy. The hips should be examined radiologically at 18 months of age in all children with bilateral cerebral palsy and at six- to 12-monthly intervals thereafter. A co-ordinated approach by orthopaedic surgeons and physiotherapists may be the key to successful implementation of this screening programme

We reviewed the evidence for hip surveillance in children with cerebral palsy from the published literature. Publications were identified using the Cochrane controlled trials register, the MEDLINE, EMBASE and CINAHL databases and by hand searching key journals and their references. Studies were included if they reported the frequency, associated risk factors or surveillance measures undertaken to identify subluxation or dislocation of the hip in children with cerebral palsy. Assessment of the quality of the methodology was undertaken independently by two researchers. Four studies described the natural history, incidence and risk factors for dislocation of the hip. Two reported their surveillance results. Approximately 60% of children who were not walking by five years of age were likely to develop subluxation of the hip, with the greatest risk in those with severe neurological involvement. The introduction of surveillance programmes allowed earlier identification of subluxation and reduced the need for surgery on dislocated hips. Surveillance can identify children most at risk of subluxation using radiological methods which are widely available

Pelvic obliquity is a common finding in adolescents with cerebral palsy, however, there is little agreement on its measurement or relationship with hip development at different gross motor function classification system (GMFCS) levels. . The purpose of this investigation was to study these issues in a large, population-based cohort of adolescents with cerebral palsy at transition into adult services. . The cohort were a subset of a three year birth cohort (n = 98, 65M: 33F, with a mean age of 18.8 years (14.8 to 23.63) at their last radiological review) with the common features of a migration percentage greater than 30% and a history of adductor release surgery. . Different radiological methods of measuring pelvic obliquity were investigated in 40 patients and the angle between the acetabular tear drops (ITDL) and the horizontal reference frame of the radiograph was found to be reliable, with good face validity. This was selected for further study in all 98 patients. . The median pelvic obliquity was 4° (interquartile range 2° to 8°). There was a strong correlation between hip morphology and the presence of pelvic obliquity (effect of ITDL on Sharpe’s angle in the higher hip; rho 7.20 (5% confidence interval 5.59 to 8.81, p < 0.001). This was particularly true in non-ambulant adolescents (GMFCS IV and V) with severe pelvic obliquity, but was also easily detectable and clinically relevant in ambulant adolescents with mild pelvic obliquity. . The identification of pelvic obliquity and its management deserves closer scrutiny in children and adolescents with cerebral palsy. Cite this article: Bone Joint J 2015;97-B:1435–40

Botulinum toxin A (BoNT-A) is a substance that requires repeated application due to its effectiveness being lost 12–16 weeks post application. Performing these intra-muscular injections under anesthesia reduces pain and distress during applications, ensuring effective and successful functional results. This study evaluates motor development of patients undergoing 3 or more repeated BoNT-A application in a tertiary pediatric hospital and the safety as well as effect of 3 different types of anesthesia. 75 children with cerebral palsy who underwent BoNT-A application at least three times consecutively with 6-month intervals and a total of 320 procedures admitted between January 2008 and January 2018 were retrospectively examined. Gross Motor Function Classification System (GMFCS) was employed in motor development evaluation. To observe the improvement in motor development, those with 2-1-0 level decreases in GMFCS classes were grouped and compared in terms of birth time, birth weight, cerebral palsy type and first BoNT-A application age. The 3 types of anesthesia methods (sedation analgesia, larengeal mask anesthesia (LMA) and inhalation mask anesthesia) applied during the procedures were compared in terms of sedation, procedure, recovery and total operation room time. The mean age of the children for all procedures was 45.51 ± 22.40 months. As a result of procedures, significant motor development was observed in 60 (80%) patients (p <0,000∗). No significant difference was observed when the children with cerebral palsy whose GMFCS declined in the form of level 2, 1 and unchanged were compared in terms of first application age, birth weight and gestational age. It was found that 106 (33.1%) were applied sevoflurane with anesthesia mask, 103 (32.1%) were administered sevoflurane with laryngeal mask, and 111 (34.6%) were sedation-analgesia. Only 10 out of 320 procedures were seen to develop side effects (8 vomiting, 2 bronchospasm). In the patients who underwent sedation analgesia during the first 3 BoNT-A procedures, the duration of recovery and total operating room time was seen to be significantly shorter than the others, while there was no difference between the anesthesia methods in the 4th and subsequent procedures. Regardless of the type of anesthesia, the recovery and total operating room times of those having undergone 6 or more procedures were longer than those with less than 6 procedures (p <0.009, p <0.016, respectively). As conclusion, repeated BoNT-A applications in children with CP provides progress in motor steps, it can be applied safely and effectively under anesthesia. Sedation analgesia application provides easier recovery compared to general anesthesia with LMA and mask only in the first three applications. However, recovery time increases with 4 and more repeated applications as the number of applications increases

Aims. Hip displacement, common in patients with cerebral palsy (CP), causes pain and hinders adequate care. Hip reconstructive surgery (HRS) is performed to treat hip displacement; however, only a few studies have quantitatively assessed femoral head sphericity after HRS. The aim of this study was to quantitatively assess improvement in hip sphericity after HRS in patients with CP. Methods. We retrospectively analyzed hip radiographs of patients who had undergone HRS because of CP-associated hip displacement. The pre- and postoperative migration percentage (MP), femoral neck-shaft angle (NSA), and sphericity, as determined by the Mose hip ratio (MHR), age at surgery, Gross Motor Function Classification System level, surgical history including Dega pelvic osteotomy, and triradiate cartilage status were studied. Regression analyses using linear mixed model were performed to identify factors affecting hip sphericity improvement. Results. A total of 108 patients were enrolled. The mean preoperative MP was 58.3% (SD 31.7%), which improved to 9.1% (SD 15.6%) at the last follow-up. NSA and MHR improved from 156.5° (SD 11.5°) and 82.3% (SD 8.6%) to 126.0° (SD 18.5°) and 89.1% (SD 9.0%), respectively. Factors affecting the postoperative MHR were preoperative MP (p = 0.005), immediate postoperative MP (p = 0.032), and history of Dega osteotomy (p = 0.046). Conclusion. We found that hip sphericity improves with HRS. Preoperative MP, reduction quality, and acetabular coverage influence femoral head remodelling. We recommend that surgeons should consider intervention early before hip displacement progresses and that during HRS, definite reduction and coverage of the femoral head should be obtained. Cite this article: Bone Joint J 2021;103-B(1):198–203

1. Thirteen years of experience in charge of treatment in a Residential School for Cerebral Palsy, and a review of 466 operations performed on children handicapped by this condition, form the basis for this attempt to frame the indications and contra-indications for operation. 2. A brief description is given of the more commonly performed operations, with an indication of the results that are likely to be obtained. 3. Orthopaedic surgery has a worth-while contribution to make in the treatment of cerebral palsy. When the cases are selected with care, when the appropriate orthopaedic measures are skilfully performed and when the patients are adequately supervised afterwards, the benefits of surgery are greater than those provided by any other treatment, and they are achieved more quickly. 4. The desire to improve and the "inner urge" of the patient to succeed may be the most important single factor in his rehabilitation

This study compares the initial outcomes of minimally invasive techniques for single-event multi-level surgery with conventional single-event multi-level surgery. The minimally invasive techniques included derotation osteotomies using closed corticotomy and fixation with titanium elastic nails and percutaneous lengthening of muscles where possible. A prospective cohort study of two matched groups was undertaken. Ten children with diplegic cerebral palsy with a mean age of ten years six months (7.11 to 13.9) had multi-level minimally invasive surgery and were matched for ambulatory level and compared with ten children with a mean age of 11 years four months (7.9 to 14.4) who had conventional single-event multi-level surgery. Gait kinematics, the Gillette Gait Index, isometric muscle strength and gross motor function were assessed before and 12 months after operation. The minimally invasive group had significantly reduced operation time and blood loss with a significantly improved time to mobilisation. There were no complications intra-operatively or during hospitalisation in either group. There was significant improvement in gait kinematics and the Gillette Gait Index in both groups with no difference between them. There was a trend to improved muscle strength in the multi-level group. There was no significant difference in gross motor function between the groups. We consider that minimally invasive single-event multi-level surgery can be achieved safely and effectively with significant advantages over conventional techniques in children with diplegic cerebral palsy