The radiological assessment of pelvic obliquity in cerebral palsy and the impact on hip development

Intraobserver and Interobserver Reliability of Pelvic Obliquity Measurement Methods in Patients With Idiopathic Scoliosis

BACKGROUND

Despite the importance of the assessment of pelvic obliquity, especially in the planning of surgery, there is no consensus on the pelvic obliquity measurements. The purpose of this study is to assess the intraobserver and interobserver reliability of 4 different pelvic obliquity measuring methods in patients with idiopathic scoliosis (IS): the Osebold, O'Brien, Maloney, and Allen&Ferguson methods.

METHODS

A retrospective cohort of 85 posteroanterior full-spine radiographs in the standing position of patients with IS involving the pelvic obliquity was evaluated by a team of 3 raters. The same researcher recorded the curve magnitude, apical vertebral rotation, Risser grade, curve pattern, and femoral head height difference. The pelvic obliquity angle was measured using the Osebold, O'Brien, Maloney, and Allen&Ferguson methods. The same graders were asked to regrade the same radiographs after at least 1 month.

RESULTS

The Osebold method showed the highest interobserver reliability with an ICC of 0.994 and 0.983. The Allen&Ferguson method had the lowest reliability with an ICC of 0.911 and 0.934, but all of the methods were considered having excellent reliability. The Osebold method also showed the highest intraobserver reliability, ranging from 0.909 to 0.997. The Allen&Ferguson method had the lowest intraobserver reliability, with a range of 0.741 to 0.960. Also, all observers preferred the Osebold Method. The observers reported that the Allen&Ferguson method was considered the most time-consuming method, while the least time-consuming method was specified as the Osebold method.

CONCLUSIONS

To the best of our knowledge, this study is the first to evaluate the intraobserver and interobserver reliability of pelvic obliquity among common measurement methods in patients with idiopathic scoliosis. All methods were evaluated as having excellent to good reliability in this study, but the Osebold method is the most reliable method of measuring pelvic obliquity on a frontal view radiograph in idiopathic scoliosis. The Osebold method is easier to use as it requires only the iliac crests to be visualized.

LEVEL OF EVIDENCE

Level III-Retrospective cohort study.

The relationship between hip displacement, scoliosis, and pelvic obliquity in 106 nonambulatory children with cerebral palsy: a longitudinal retrospective population-based study

BACKGROUND AND PURPOSE

The relationship between hip displacement (HD), pelvic obliquity (PO), and scoliosis in nonambulatory children with cerebral palsy (CP) has not been clearly elucidated. The aims of this population-based study were to examine the prevalence and temporal sequence of these deformities in nonambulatory children with CP and to evaluate how probable it is that severe unilateral HD contributes to development of scoliosis.

PATIENTS AND METHODS

This longitudinal study comprised 106 nonambulatory children, enrolled in a surveillance program. Pelvic radiographs for measurements of migration percentage (MP) and PO were taken once a year from the diagnosis of HD. Spine radiographs were taken in patients with clinically detected scoliosis. Radiographic follow-up continued until skeletal maturity.

RESULTS

Clinically significant scoliosis (Cobb angle ≥ 40°) occurred in 60 patients at a mean age of 11.8 years. 65 patients developed clinically significant HD (MP ≥ 40%) at a mean age of 4.8 years. 24 patients had no significant hip or spine deformities, 22 had HD only, 17 had scoliosis only, and 43 had both deformities. HD was diagnosed before scoliosis in all except 1 of the patients with both deformities. 14 of 19 patients with severe unilateral HD (MP ≥ 60%) had scoliosis convexity to the opposite side of the displaced hip.

CONCLUSION

The combination of scoliosis and HD was frequent, and HD was diagnosed first in almost all the patients. HD might be a contributory cause of scoliosis in patients with severe, unilateral HD, PO, and later scoliosis with convexity to the opposite side.

The Ambiguity of Names and Landmarks in Radiographs of the Pediatric Pelvis: Variations and a Historical Perspective

For over a century, the plain radiograph has been used to measure and predict the development of pediatric hip conditions. Classic measurements, such as the acetabular index, the center-edge angle, and the migration percentage, have stood the test of time and remain the default tools for any pediatric orthopaedic surgeons. However, in contemporary research, the terminology regarding these measurements has become markedly inconsistent. A substantial number of synonyms, acronyms, and similar, but not identical, terms are used to label measurements. This is perhaps unsurprising, considering decades of use and numerous suggested modifications. The results of treatment cannot be reliably compared if the measured parameters are not identical, and scientific analysis of disease requires consistent terminology. In this review, we aim both to provide historical definitions and identification of radiographic landmarks commonly used in three parameters of interest on pediatric AP radiographs and to examine the variability of landmarks and definitions in contemporary research.

Hip Displacement After Triradiate Cartilage Closure in Nonambulatory Cerebral Palsy: Who Needs Continued Radiographic Surveillance?

BACKGROUND

Recommendations with regard to the need for continued hip surveillance after skeletal maturity are based on expert opinion rather than evidence. This study aimed to determine the prevalence of and risk factors associated with progressive hip displacement in cerebral palsy (CP) after triradiate cartilage (TRC) closure.

METHODS

Patients who had spastic nonambulatory CP (Gross Motor Function Classification System IV to V) and hypertonic (spastic or mixed-type) motor type and follow-up of at least 2 years after TRC closure were included. The primary outcome variable was the hip migration percentage (MP). The secondary outcome variables included patient age at the time of TRC closure, prior preventative or reconstructive surgery, a prior intrathecal baclofen pump, history of scoliosis, history of epilepsy, a prior gastrostomy tube, a previous tracheostomy, and gender. An unsuccessful hip outcome was defined as a hip with an MP of ≥40% and/or requiring a reconstructive surgical procedure after TRC closure.

RESULTS

In this study, 163 patients met the inclusion criteria, with a mean follow-up of 4.8 years (95% confidence interval [CI], 4.4 to 5.1 years) after TRC closure at a mean patient age of 14.0 years (95% CI, 13.7 to 14.3 years). Of these hips, 22.1% (36 of 163) had an unsuccessful hip outcome. In multivariate analysis, the first MP at TRC closure (hazard ratio [HR] per degree, 1.04; p < 0.001) and pelvic obliquity (HR per degree, 1.06; p = 0.003) were independent risk factors for an unsuccessful hip outcome, but gender was not found to be significant (HR for male gender, 1.7 [95% CI, 0.8 to 3.58; p = 0.16]; female gender was the reference). However, the mean survival time for progression to an unsuccessful hip outcome was longer for female patients at 9.2 years [95% CI, 8.1 to 10.2 years]) compared with 6.2 years (95% CI, 5.6 to 6.9 years) for male patients (p = 0.02). There was also a significant improvement in survivorship for prior reconstructive surgical procedures (p = 0.002). The survivorship in patients who underwent reconstructive surgery performed at a patient age of ≥6 years was significantly higher compared with those who underwent surgery performed at <6 years of age (p < 0.05). A first MP at TRC closure of ≥35% was associated with an unsuccessful hip outcome, as determined by receiver operating characteristic (ROC) curve analysis (p < 0.001; area under the ROC curve of 0.891, sensitivity of 81%, and specificity of 94%).

CONCLUSIONS

The risk factors for the progression of hip displacement after TRC closure in patients with CP included a higher MP and increased pelvic obliquity; there was decreased survivorship for male patients and patients with no prior reconstructive surgery. Patients with these risk factors and/or an MP of ≥35% at TRC closure should have continued radiographic surveillance to detect late hip displacement.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Unilateral versus bilateral reconstructive hip surgery in children with cerebral palsy: A survey of pediatric orthopedic surgery practice and decision-making

PURPOSE

This study explored whether surgeons favor unilateral or bilateral reconstructive hip surgery in children with cerebral palsy who have unilateral hip displacement.

METHODS

An invitation to participate in an anonymous, online survey was sent to 44 pediatric orthopedic surgeons. The case of an 8 year old at Gross Motor Function Classification System level IV with migration percentages of 76% and 22% was described. Surgeons selected their surgical treatment of choice and provided their rationale. Respondents were also asked to list and rank radiographic parameters used for decision-making and multidisciplinary team members involved in decision-making.

RESULTS

Twenty-eight orthopedic surgeons from nine countries with a mean 21.3 years (range, 5-40 years) of experience completed the survey. A "bilateral VDROs with a right pelvic osteotomy (PO) was selected by 68% (19/28) of respondents; risk of contralateral subluxation (9/19; 47%) and maintaining symmetry (7/19; 37%) were the most common rationales for bilateral surgery. The remaining 32% (9/28) chose a 'right VDRO with a right PO'" with most of these (8/9; 89%) stating the left hip was sufficiently covered. Of 31 radiographic parameters identified, migration percentage, acetabular angle/index, Shenton line, neck shaft angle, and presence of open/closed triradiate growth plates were the most common. Physical therapists (68%) and physiatrists (43%) were most likely to be involved in pre-operative surgical consultation.

CONCLUSION

There is a lack of agreement on management of the contralateral hip in children with unilateral hip displacement. Further studies comparing patient important outcomes following unilateral and bilateral surgery are required.

LEVEL OF EVIDENCE

V.

Late Hip Displacement Identified in Children at Gross Motor Function Classification System II and III With Asymmetric Diplegia and Fixed Pelvic Obliquity

Risk of hip displacement in children with cerebral palsy is directly related to a child's level of motor function as classified by the Gross Motor Function Classification System (GMFCS) and is reported to be greatest at a young age. In this study, we present a series of four children with asymmetric diplegic cerebral palsy at GMFCS levels II and III, with the more involved hip showing rapid, progressive displacement at a later age. Current hip surveillance guidelines may not adequately identify hip displacement in children with asymmetric diplegia and pelvic obliquity; modifications to surveillance guidelines may be warranted. Additional investigation of hip displacement in this subset of children is required to determine whether the incidence of displacement is higher than anticipated based on the GMFCS level alone.

Imaging Parameters of Hip Dysplasia in Cerebral Palsy: A Systematic Review

Background

Cerebral Palsy is the leading cause of childhood physical disability globally. The motor disorders of CP are often associated with musculoskeletal anomalies, of which hip displacement is the second most common abnormality after abnormalities of foot and ankle. Various radiological parameters have been described in the literature which detects and quantifies hip dysplasia, with MP being the current gold standard. This study aims to review these radiological indicators of hip dysplasia in children with cerebral palsy from the published literature.

Methods

A literature search using PubMed, Embase, and Google Scholar was done on 15th June 2021 focusing on surveillance of hip dysplasia in cerebral palsy. The studies to be included were to have used anyone or more radiological parameter for detection of hip dysplasia with the use of any of the radiological methods.

Results

The initial search yielded 1184 results. After the screening of the abstracts and full texts, a final of 30 studies was included for this systematic review. The majority of the studies were graded as Level 3 evidence (16/30), followed by Level 2 studies (14/30). X-ray was the most common modality of detection of dysplasia followed by CT scan, ultrasonography, and arthrogram. The reproducibility of the various parameters shows good to excellent intraclass coefficients.

Conclusions

Parameters other than MP can be used to screen hips in CP. This would be useful in patients in whom either the lateral acetabular edge is not discernible on a plain anteroposterior radiograph or there are issues in the positioning of the patient. Additional views and structures can be visualized which can lead to improved screening and planning. Further investigations are required to appreciate the full potential of these parameters and how they can be better utilized.

Graphical abstract

Long-Term Evolution of the Hip and Proximal Femur after Hip Reconstruction in Non-Ambulatory Children with Cerebral Palsy: A Retrospective Radiographic Review

Background: Hip displacement in children with cerebral palsy (CP) has a higher prevalence in non-ambulatory children. Progression can lead to pain, pelvic obliquity and difficulty with sitting. This can be addressed with hip reconstruction. Our study aims to report the long-term radiological outcomes after hip reconstruction, in particular the evolution of femoral head deformity. Methods: A total of 58 hips of non-ambulatory children with CP were evaluated retrospectively using pre-operative, early (median 120 days) and late post-operative (median 8.6 years) anteroposterior standardised radiographs. All the hips were treated with femoral shortening varus derotation osteotomy (VDRO), pelvic osteotomy and an open reduction, if indicated. The radiographical indices measured included the migration percentage (MP), sharp angle, acetabular index, centre-edge angle, neck shaft angle, head shaft angle, pelvic obliquity, femoral head sphericity, femoral head deformity (FHD) and growth plate orientation. Results: Improvements in hip congruency and morphology were evident after reconstructive hip surgery. These were maintained at the late post-operative time point. Median MP improved from 56% (IQR 46–85%) to 0% (IQR 0–15%) at early follow-up. This increased to 12% (IQR 0–20%) at late follow-up. Pre-operatively, FHDs of 14 hips (24%) were classified as grade A (spherical femoral head). This increased to 22 hips (38%) at early follow-up and increased further to 44 hips (76%) at late follow-up. Conclusions: Our study shows that hip reconstruction reduces hip displacement in the long term, indicated by decreased post-operative MP maintained at long-term follow-up. Although non-ambulatory children lack weight-bearing forces promoting bone remodelling, improved femoral head morphology after surgery alters the forces between the acetabulum and the femoral head. Mild femoral head deformity (grades A and B) remained stable and even improved after surgery, postulated to be due to severe osteoporosis allowing remodelling.

Australian hip surveillance guidelines at 10 years: New evidence and implementation

Optimum management of hip displacement in children with cerebral palsy (CP) is facilitated by an approach that focuses on anticipatory and preventive measures. Hip surveillance programs for children with CP were developed at the beginning of the new millennium, with the purpose of identifying hip displacement sufficiently early to permit a choice of effective management options. In the early years, hip surveillance was guided by epidemiological analysis of population-based studies of prevalence. In Australia, a National Hip Surveillance in CP Working Group was first convened in 2005. This resulted in a 2008 Consensus Statement of recommendations published and endorsed by Australasian Academy of Cerebral Palsy and Developmental Medicine (AusACPDM). The group undertook that the recommendations should be reviewed every 5 years to ensure currency and congruency with the emerging evidence base. As new evidence became available, hip surveillance guidelines developed, with the most recent 2020 Australian Hip Surveillance Guidelines endorsed by the AusACPDM. Implementing comprehensive hip surveillance programs has now been shown to improve the natural history of hip dislocations and improve quality of life. Standardised hip surveillance programs can also facilitate planning for multicentre research through harmonisation of data collection. This, in turn, can help with the identification of robust new evidence that is based on large cohort or population studies. Here a review of evidence informing the updated 2020 Hip Surveillance Guidelines is presented.

Pelvic obliquity associated with neuromuscular scoliosis in cerebral palsy: cause and treatment

STUDY DESIGN

Literature Review.

OBJECTIVE

Review the etiology, clinical manifestations, diagnosis, and treatment of pelvic obliquity in cerebral palsy patients with neuromuscular scoliosis. Neuromuscular scoliosis (NMS) in cerebral palsy (CP) patients is rapidly progressive and often leads to an imbalance in musculoskeletal mechanics that extends to the pelvis. A horizontal misalignment of the pelvis in the frontal plane known as pelvic obliquity (PO) is a common finding in this population. When untreated, PO can exacerbate the back pain, postural strain, and walking difficulties experienced by these patients. Establishing the manifestation and treatment plan for PO in the setting of NMS can provide valuable insight for diagnosis and management.

METHODS

A comprehensive literature review was performed on the etiology, clinical manifestations, diagnosis, and treatment of pelvic obliquity in the setting of NMS in CP. The advantages and limitations of measurement and treatment options were evaluated.

RESULTS

PO is categorized into suprapelvic, infrapelvic, and intrapelvic causes, each presenting with a unique pattern of pathology. NMS in CP with hip contractures and structural deformities fall into these categories. The Maloney and O'Brien methods of pelvic measurement have demonstrated superior utility and are recommended for clinical diagnosis. The management of PO in NMS patients is focused on the cause of malalignment, with posterior fusion, contracture release, and osteotomy encompassing the mainstay of treatment.

CONCLUSION

PO is commonly found in patients with NMS in cerebral palsy. There is currently no standard method for determining the PO angle. Interventions designed to reduce scoliotic curves and release tissue contractures can level the pelvis and restore proper alignment of the spine and sacrum in the coronal plane in these patients. Further understanding of the causes of PO in NMS, as well as the establishment of a standardized measuring technique and diagnostic parameters will allow for more effective treatment options and improve outcomes in patients with CP.

LEVEL OF EVIDENCE

N/A.

Hip subluxation and osteophye morphology are related to coronal contracture of the hip

Coronal hip contracture induces pelvic obliquity in the presence of hip osteoarthritis (HOA), followed by the functional leg-length discrepancy. To promote accurate diagnosis of contracture and proper management of soft tissue release in total hip arthroplasty (THA), this study aimed to clarify the morphological features on plain radiographs that are related to contracture in patients with HOA. Two hundred forty-three hips of 231 patients with HOA who underwent primary THA were included in this study. Preoperative pelvic radiographs of the bilateral hips in maximum adduction and abduction were used to quantify contracture. Patients were grouped according to their contracture as having abduction contracture, adduction contracture, or minimal contracture. We investigated HOA, subluxation, anatomical factors, spinal factors, and the morphology of osteophytes at the inferomedial femoral head and compared parameters among groups to clarify the predictors of contracture. Eighteen hips (7.6%) were classified as having adduction contracture and 23 (9.4%) as having abduction contracture. Crowe classification, leg-length discrepancy, and osteophyte morphology showed significant correlations with adduction contracture. Factors significantly correlated with abduction contracture were offset difference, pelvic obliquity, functional femoral anteversion, and osteophyte morphology. Multivariate logistic regression analysis showed that the factor most strongly related to adduction contracture was Crowe III classification, whereas the strongest predictor of abduction contracture was osteophyte morphology. In conclusion, hip subluxation was related to the adduction contracture of the hip, whereas osteophyte morphology was related to abduction contracture.

Residual lumbar hyperlordosis is associated with worsened hip status 5 years after scoliosis correction in non-ambulant patients with cerebral palsy

BACKGROUND

Cerebral palsy (CP) is a static encephalopathy with progressive musculoskeletal pathology. Non-ambulant children (GMFCS IV and V) with CP have high rates of spastic hip disease and neuromuscular scoliosis. The effect of spinal fusion and spinal deformity on hip dislocation following total hip arthroplasty has been well studied, however in CP this remains largely unknown. This study aimed to identify factors associated with worsening postoperative hip status (WHS) following corrective spinal fusion in children with GMFCS IV and V CP.

METHODS

Retrospective review of GMFSC IV and V CP patients in a prospective multicenter database undergoing spinal fusion, with 5 years follow-up. WHS was determined by permutations of baseline (BL), 1 year, 2 years, and 5 years hip status and defined by a change from an enlocated hip at BL that became subluxated, dislocated or resected post-op, or a subluxated hip that became dislocated or resected. Hip status was analyzed against patient demographics, hip position, surgical variables, and coronal and sagittal spinal alignment parameters. Cutoff values for parameters at which the relationship with hip status was significant was determined using receiver operating characteristic curves. Logistic regression determined odds ratios for predictors of WHS.

RESULTS

Eighty four patients were included. 37 (44%) had WHS postoperatively. ROC analysis and logistic regression demonstrated that the only spinopelvic alignment parameter that significantly correlated with WHS was lumbar hyperlordosis (T12-L5) > 60° (p = 0.028), OR = 2.77 (CI 1.10-6.94). All patients showed an increase in pre-to-postop LL. Change in LL pre-to-postop was no different between groups (p = 0.318), however the WHS group was more lordotic at BL and postop (pre44°/post58° vs pre32°/post51° in the no change group). Age, sex, Risser, hip position, levels fused, coronal parameters, global sagittal alignment (SVA), thoracic kyphosis, and reoperation were not associated with WHS.

CONCLUSION

Postoperative hyperlordosis(> 60°) is a risk factor for WHS at 5 years after spinal fusion in non-ambulant CP patients. WHS likely relates to anterior pelvic tilt and functional acetabular retroversion due to hyperlordosis, as well as loss of protective lumbopelvic motion causing anterior femoracetabular impingement.

LEVEL OF EVIDENCE

III.

Is the Gothic Arch a reliable radiographic landmark for migration percentage in children with cerebral palsy?

INTRODUCTION

Reimers migration percentage (MP) is the gold standard for measuring hip displacement in children with cerebral palsy (CP). Hip surveillance registries proposed using the top of the Gothic arch (GA) as a modification in patients with acetabular dysplasia because the classical method (CM) described by Reimers may underestimate hip migration. The aim of this study is to assess the inter- and intra-observer reliability of the modified method (MM) versus the CM and identify their effect on the MP.

METHODS

We performed a retrospective review of 50 children with CP, who had a hip radiograph at our institution between 1st April 2014 and 28th February 2018. All hip radiographs were carefully selected to show the presence of a GA. Four observers measured the MP using the CM and MM for each patient. Interclass coefficient was used to estimate inter- and intra-observer reliability.

RESULTS

Inter-observer reliability was excellent for the CM with ICC 0.96 (95% CI 0.94 to 0.97) and good for the MM, ICC 0.78 (95% CI 0.51 to 0.89) p < 0.001. Intra-observer reliability was excellent for both methods raging from ICC 0.94 to 0.99 for the CM and ICC 0.89 to 0.95 for the MM. The mean MP was 19% for the CM and 28% for the MM (p < 0.001).

CONCLUSION

The CM is more reliable than the MM to measure hip migration in children with CP. If the CM is used and acetabular dysplasia with a GA are present on the hip radiograph, then a 9% hip migration underestimation should be considered on decisions for both referral and surgical management.

LEVEL OF EVIDENCE

II.

Outcome of Femoral Varus Derotational Osteotomy for the Spastic Hip Displacement: Implication for the Indication of Concomitant Pelvic Osteotomy

No previous studies have suggested a reliable criterion for determining the addition of a concomitant pelvic osteotomy by using a large patient cohort with quadriplegic cerebral palsy and a homogenous treatment entity of femoral varus derotational osteotomies (VDRO). In this retrospective study, we examined our results of hip reconstructions conducted without a concomitant pericapsular acetabuloplasty in patients with varying degrees of hip displacement. We wished to investigate potential predictors for re-subluxation or re-dislocation after the index operation, and to suggest the indications for a simultaneous pelvic osteotomy. We reviewed the results of 144 VDROs, with or without open reduction, in 72 patients, at a mean follow-up of 7.0 (2.0 to 16.0) years. Various radiographic parameters were measured, and surgical outcomes were assessed based on the final migration percentage (MP) and the Melbourne Cerebral Palsy Hip Classification Scale (MCPHCS) grades. The effects of potential predictive factors on the surgical outcome was assessed by multivariate regression analysis. A receiver operating characteristic (ROC) curve analysis was also performed to determine whether a threshold of each risk factor existed above which the rate of unsatisfactory outcomes was significantly increased. In total, 113 hips (78.5%) showed satisfactory results, classified as MCPHCS grades I, II, and III. Thirty-one hips (21.5%) showed unsatisfactory results, including six hip dislocations. Age at surgery and preoperative acetabular index had no effects on the results. Lower pre- and postoperative MP were found to be the influential predictors of successful outcomes. The inflection point of the ROC curve for unsatisfactory outcomes corresponded to the preoperative MP of 61.8% and the postoperative MP of 5.1%, respectively; these thresholds of the pre- and postoperative MP may serve as a guideline in the indication for a concomitant pelvic osteotomy. Our results also indicate that the severely subluxated or dislocated hip, as well as the hip in which the femoral head is successfully reduced by VDRO but is still contained within the dysplastic acetabulum, may benefit from concomitant pelvic osteotomy.

Reliability of Radiographic Assessments of the Hip in Cerebral Palsy

INTRODUCTION

Children with cerebral palsy are at risk for progressive hip displacement. Since surveillance for hip displacement uses specific radiographic measurements to guide decision making, it is important to establish the reliability of these measurements, which include Reimer's migration percentage (MP), acetabular index or acetabular angle (AI or AA), and pelvic obliquity (PO). The purpose of this study was to determine the intraobserver and interobserver reliability of these radiographic measures among an international group of pediatric orthopaedic surgeons participating in the prospective international multicenter Cerebral Palsy Hip Outcomes Project (CHOP) currently underway to evaluate the outcomes of hip interventions in cerebral palsy.

METHODS

Two compact discs (CDs) containing the same 25 anteroposterior pelvis radiographs in Digital Imaging and Communications in Medicine (DICOM) format were provided to participating surgeons at least 2 weeks apart. To reduce the likelihood of recall or any effects of learning or fatigue, the order of the radiographs varied on the 2 CD versions, and participating surgeons received the 2 CDs in random order. The intraclass correlation coefficients (ICCs) were calculated to assess interobserver and intraobserver reliability. Mean absolute differences of hip measurements obtained at 2 time points were also calculated.

RESULTS

The MP had the highest reliability followed by PO, AI, and AA with a mean intrarater ICC (SD; range) of 0.95 (0.04; 0.84 to 0.98); 0.92 (0.03; 0.85 to 0.97); 0.84 (0.05; 0.75 to 0.92); and 0.82 (0.14; 0.51 to 0.98); respectively. The mean interrater ICC (SD; range) for MP, PO, AI, and AA were 0.94 (0.05; 0.78 to 0.99); 0.90 (0.04; 0.76 to 0.99); 0.79 (0.08; 0.52 to 0.93); and 0.69 (0.23; 0.42 to 0.98) for MP, PO, AI, and AA, respectively. The mean (SD; 95% confidence interval) for the absolute difference between the 2 measurements for the raters was 4.9% (2.9%; 3.4%-6.4%); 3. 8 degrees (1.2 degrees; 3.1-4.5 degrees); 2.6 degrees (1.5 degrees; 1.7-3.5 degrees); and 1.3 degrees (0.3 degrees; 1.29-1.31 degrees) for MP, AI, AA, and PO, respectively.

CONCLUSIONS

MP is a reproducible measure with excellent intrarater and interrater reliability. However, differences in MP of <7% should be treated with caution as these might be a consequence of measurement error. Although we found a high level of intrarater and interrater reliability of the AI, AA, and PO, these measurements are more variable and not ideal for use as discrete outcome measures. Instead, these parameters might be useful for prognostication and decision making when consistent trends are observed longitudinally over time which might be better indications of true change.

Patterns of hip migration in non-ambulant children with cerebral palsy: A prospective cohort study

BACKGROUND

In children with cerebral palsy (CP), we have little information on when hip migration (HM) starts, what causes hip displacement, how HM changes over time, and how to halt this migration to avoid surgery.

OBJECTIVES

We aimed to estimate the prevalence of HM percentage (HMP)>40% in a homogeneous population of non-ambulant children with CP and model the changes in HMP over a 2.6-year mean follow-up.

METHODS

From September 2009 to September 2015, this observational, prospective, multicenter cohort study recruited 235 children from 51 centers who were 3 to 10 years old and had levels IV and V of the Gross Motor Function Classification System for CP. The outcomes were yearly HMP measurements by the Reimers index. Only children with at least one hip with HMP≤40% at baseline were included in trajectory modeling. Comparisons of chidren's characteristics between trajectory groups were adjusted by the false discovery rate method.

RESULTS

The prevalence of children with at least one hip with HMP>40% was estimated at 24.3% (95% confidence interval 18.6-30.0). Pelvic obliquity was observed in 51.4% and 24.4% of children with asymmetric and symmetric HMP (P=0.002). The trajectory modelling identified 3 types of MP changes over time. Many children (67.4% and 79.3% for the right and left hip) could be assigned to the "stable" trajectory group.

CONCLUSIONS

In non-ambulant children with CP, the prevalence of HM requiring surgery is low and most hips remain practically stable over time.

Inter- and Intraobserver Reliability of Pelvic Obliquity Measurement Methods in Patients With Cerebral Palsy

STUDY DESIGN

Retrospective, chart review.

OBJECTIVES

The identification and management of pelvic obliquity in neuromuscular scoliosis can be difficult; therefore, appropriate evaluation of this pathology is important. Variations in presentation have resulted in various methods of measurement, without a consensus or gold standard measurement. This study is the evaluation of reliability of five methods commonly used to determine pelvic obliquity in the frontal plane.

SUMMARY OF BACKGROUND DATA

Previous studies have used five different methods (ie, the Maloney method, the O'Brien method, the Osebold method, the Allen and Ferguson method, and the Lindseth method) to determine pelvic obliquity in the frontal plane.

METHODS

Radiographic images of 50 patients with neuromuscular scoliosis involving the pelvic girdle were identified and evaluated by a team of 5 raters. Each rater was instructed to apply five commonly used methods of measuring pelvic obliquity. The same raters were asked to rate the same radiographs again after a minimum of one month. The interobserver reliability was assessed using the intraclass correlation coefficient (ICC) and the intraobserver analysis was assessed using the Pearson correlation. A rating greater than 0.8 was considered excellent reliability.

RESULTS

The Maloney method showing the highest interobserver reliability of ICC of 0.965 and 0.964. The Lindseth method had the lowest ICC, but all the methods were considered highly reliable by the rating classification system. The Maloney method also showed the highest intraobserver reliability, ranging from 0.845 to 0.962. The Allen and Ferguson method had the lowest intraobserver reliability.

CONCLUSIONS

Many of the methods tested had excellent reliability in this study, but our data suggest the Maloney method is the most reliable method of measuring pelvic obliquity on a frontal view radiograph.

LEVEL OF EVIDENCE

Level III, retrospective, comparative study.

Pelvic obliquity and measurement of hip displacement in children with cerebral palsy

Background and purpose - Pelvic obliquity, common in individuals with cerebral palsy (CP), changes the muscle force vector on the hip joint and probably affects the risk of hip dislocation. We evaluated a new method for measurement of hip displacement in CP that takes the pelvic obliquity into account: the pelvic adjusted migration percentage (PAMP). Children and methods - From the Swedish surveillance program for cerebral palsy (CPUP), the first pelvic radiograph of 268 children <18 years in southern Sweden during a 3-year period were evaluated. Pelvic obliquity, PAMP, and the migration percentage (MP) were measured. 50 radiographs were randomly selected for analysis of interrater reliability by three raters using the intraclass correlation coefficient (ICC). The correlations between PAMP/MP and pelvic obliquity were analyzed with Pearson correlation coefficients. Results - The interrater reliability for all 3 measurements was high (ICCs 0.88-0.97). The correlation between the high side of the pelvic obliquity and the difference between right and left hip displacement was higher for PAMP (r = 0.70) than for MP (r = 0.41). Interpretation - The new PAMP measurement showed high interrater reliability and a higher correlation with pelvic obliquity than MP. We suggest the use of PAMP at least in hips with a pelvic obliquity exceeding 5°.

Natural history of scoliosis in cerebral palsy and risk factors for progression of scoliosis

BACKGROUND

Scoliosis in cerebral palsy (CP) often occurs and causes a disturbance in daily life. The purpose of this study was to investigate the natural history of scoliosis in cerebral palsy and determine risk factors for the progression of scoliosis using multivariate analyses.

METHODS

We revised 113 patients with CP (47 males and 66 females) who had scoliosis with a curve of at least 10° were reviewed and retrospectively investigated these cases of scoliosis and analyzed the risk factors for the progression of this condition.

RESULTS

The mean follow-up period was 16.5 years and the mean age at onset of scoliosis was 6.6 years (range: 1-16 years). In 59 patients (52%), the age at onset of scoliosis was under 6 years. On the final radiographs, the mean Cobb angle was 55.1° (range: 10° to 169°). After the age of 20 years, 13 of 40 patients (32.5%) had a progression of over 10° in scoliosis. Multivariate analyses showed the risk factors for the progression of scoliosis to be hip displacement (p = 0.0038), the onset of scoliosis before the age of 6 years (p = 0.0024), and 30° of the Cobb angle before the age of 10 years (p < 0.001). A subtype of CP (spastic quadriplegia) was identified as a potential risk factor.

CONCLUSIONS

After the age of 20 years, 32.5% patients had a progression of over 10° in scoliosis. Risk factors for the progression of scoliosis in CP included hip displacement, early-onset scoliosis, and Cobb angle of 30° before the age of 10 years.

LEVEL OF EVIDENCE

Prognostic level IV - case series.

Postural asymmetry in non-ambulant adults with cerebral palsy: a scoping review

PURPOSE

Non-ambulant adults with cerebral palsy are vulnerable to development of postural asymmetry and associated complications. The primary aim of this scoping review was to identify postural deformities in non-ambulant adults with cerebral palsy.

MATERIALS AND METHODS

Comprehensive searches were undertaken in EMBASE, CINAHL, AMED, Cochrane, Psych INFO, and Joanna Briggs (1986-Jan 2017), supplemented by hand searching. Two reviewers independently extracted data using a customised tool focusing on study design, participant characteristics, postural descriptors, measurement tools, and interventions.

RESULTS

From 2546 potential records, 17 studies were included. Variability in populations, reporting methodology, and measurement systems was evident. Data suggest more than 30% of this population have hip migration percentage in excess of 30%, more than 75% experience "scoliosis", and more than 40% demonstrate pelvic obliquity. Estimates ranged from 14% to 100% hip and 32% to 87% knee contracture incidence. Conservative interventions were infrequently and poorly described.

CONCLUSION

Many non-ambulant adults with cerebral palsy experience postural asymmetry associated with windswept hips, scoliosis, pelvic obliquity, and limb contracture. Options for non-radiographic monitoring of postural asymmetry should be identified, and conservative interventions formally were evaluated in this population. Implications for rehabilitation The common postural asymmetries of windswept hips, scoliosis, pelvic obliquity, and limb contracture require standardised clinical measurement. Radiography is most commonly used to monitor postural asymmetry in this population, but standardised positioning is not applied and may not be feasible indicating a need for alternate methods and rigorous documentation. The Posture and Postural Ability Scale may be considered for use in the management of body shape in adults with CP.

Combined pelvic and femoral reconstruction in children with cerebral palsy

Objective

The primary aim of this study was to determine the effect of age, femoral head migration, and ambulatory status on radiographic outcomes after combined pelvic and femoral reconstruction in children with cerebral palsy. The secondary aim was to evaluate the fate of the opposite hip after unilateral reconstruction.

Methods

A retrospective cohort study design of consecutive patients from 1995–2009 was used. The records were screened for patients who underwent varus derotational osteotomy and modified Dega osteotomy.

Results

Eighty-five hips in 71 patients were included. The mean age was 8.4 ± 3.2 years and the mean follow-up was 6.6 ± 3.1 years. The final measures were a mean migration index of 20% ± 15.58%, centre edge angle of 28.45° ± 15.98°, and Sharp’s angle of 40.75° ± 8.5°. Those values were not correlated with age and the initial migration index. Nonambulatory status did not negatively affect hip stability. Final measurements of the contralateral hips were similar to the reconstructed hips, and the cumulative incidence for later reconstruction was 5.67%.

Conclusions

Regardless of age, preoperative displacement, and ambulation, the combined procedure provides durable radiographic improvement. In unilateral cases, there is a low risk of later deterioration of the opposite side.

Management of the spastic hip in cerebral palsy

PURPOSE OF REVIEW

Spastic hip dysplasia (SHD) is a common finding in patients with cerebral palsy, with a higher incidence in more involved patients, causing disability and reducing quality of life in these patients. SHD is the most serious orthopedic problem seen in cerebral palsy patients, and requires special attention and tenacious evaluation of the patients. The aim of this article is to review the new developments in the treatment of SHD.

RECENT FINDINGS

Patients with cerebral palsy were shown to have better hip joint morphology when they had access to hip surveillance programmes, with proactive search of patients with progressing hip subluxation and early intervention. Prediction of progression of SHD is now available based on the experience of these programmes.Patients who underwent hip joint reconstruction showed that incongruent joints remodeled following a Dega osteotomy. Patients who underwent a varus osteotomy of the femoral neck without pelvic reconstruction had a higher rate of recurrence when they were older and the SHD was more severe. Health-related quality of life measures improved following hip joint reconstructions and salvage procedures.

CONCLUSION

Patients with cerebral palsy should be monitored with a well-defined hip surveillance programme, with early identification and timely intervention for SHD.

A balanced approach for stable hips in children with cerebral palsy: a combination of moderate VDRO and pelvic osteotomy

BACKGROUND

Hip reconstructive surgery in cerebral palsy (CP) patients necessitates either femoral varus derotational osteotomy (VDRO) or pelvic osteotomy, or both. The purpose of this study is to review the results of a moderate varisation [planned neck shaft angle (NSA) of 130°] in combination with pelvic osteotomy for a consecutive series of patients.

METHODS

Patients with CP who had been treated at our institution for hip dysplasia, subluxation or dislocation with VDRO in combination with pelvic osteotomy between 2005 and 2010 were reviewed.

RESULTS

Forty patients with a mean follow-up of 5.4 years were included. The mean age at the time of operation was 8.9 years. The majority were non-ambulant children [GMFCS I-III: n = 11 (27.5 %); GMFCS IV-V: n = 29 (72.5 %)]. In total, 57 hips were treated with both femoral and pelvic osteotomy. The mean pre-operative NSA angle of 152.3° was reduced to 132.6° post-operatively. Additional adductor tenotomy was performed in nine hips (16 %) at initial operation. Reimers' migration percentage (MP) was improved from 63.6 % pre-operatively to 2.7 % post-operatively and showed a mean of 9.7 % at the final review. The results were good in 96.5 % (n = 55) with centred, stable hips (MP <33 %), fair in one with a subluxated hip (MP 42 %) and poor in one requiring revision pelvic osteotomy for ventral instability.

CONCLUSIONS

This approach maintains good hip abduction and reduces soft-tissue surgery. Moderate varisation in VDRO in combination with pelvic osteotomy leads to good mid-term results with stable, pain-free hips, even in patients with severe spastic quadriplegia.