Pelvis radiographs in children with cerebral palsy: effects of patient positioning on calculating migration percentages

BACKGROUND

Hip displacement in children with cerebral palsy (CP) is monitored by measuring migration percentage on anteroposterior pelvis radiographs. However, proper positioning for radiography in children with spasticity is difficult. The reliability and accuracy of migration percentage as a function of patient positioning is unknown.

OBJECTIVE

To determine the effects of patient positioning on migration percentage measurements in children with CP.

MATERIALS AND METHODS

We identified children with CP (≤18-year-old) with pelvis CT and anteroposterior pelvis radiograph obtained <6 months apart (10/2018-11/2021). Digitally reconstructed radiographs were generated from each pelvis CT, to simulate nine different patient positions: neutral; 10° and 20° lordosis and kyphosis; and 10° and 20° right rotation and left rotation. Two radiologists measured migration percentages from the simulated and real pelvis radiographs. We used Spearman's rho to assess inter-rater reliability, and Wilcoxon signed rank test to determine statistical significance.

RESULTS

We studied sixty-three children (male=41; median age=8 years; range=4-18 years). The two radiologists' migration percentage measurements were highly correlated with each other across all simulated and real radiographs (Spearman's rho=0.86-0.99, P<0.01). For both readers and hips, migration percentages measured from real radiographs were significantly different from those measured from neutral simulated radiographs (P<0.01), with median absolute difference=5-6 percentage points (PP) and interquartile range (IQR)=9-12 PP. When comparing migration percentage measurements from neutral simulated radiographs to those in kyphosis/lordosis and right/left rotations, median absolute differences were 2-4 PP (IQR=3-8 PP) and 4-15 PP (IQR=6-17 PP), respectively.

CONCLUSION

Inter-rater reliability of measured migration percentages is high, but accuracy decreases with patient positional changes.

Hip subluxation in children with spinal cord injury: Incidence and influencing factors

OBJECTIVE

Hip subluxation is a common complication in children with spinal cord injury. This study aimed to investigate the incidence and influencing factors of hip subluxation and discuss prevention strategies.

METHODS

Medical records of children with spinal cord injury were reviewed. The inclusion criteria were as follows: (1) the patient was younger than 18 years old when injured; (2) absence of traumatic or congenital pathological changes of the hip at the time of injury. The migration percentage and acetabular index were selected to evaluate hip stability and acetabulum development. Influencing factors of sex, age, injury duration, severity, level, and spasticity were analyzed.

RESULTS

A total of 146 children were enrolled. Twenty-eight children presented with hip subluxation and were significantly younger at the time of injury than those with normal hips (P = 0.002). The incidence of hip subluxation increased with the prolonged injury duration. Injury before age 6, complete injury, and flaccid lower extremities were significant influencing factors (P = 0.003, 0.004, and 0.015, respectively). The risk of hip subluxation decreased by 18% for every year older in injury age (P = 0.031) and decreased by 85% in children with spasticity (P = 0.018) than those without. However, the risk of hip subluxation in children with injury duration longer than 1 year was 7.1 times higher than those with shorter injury duration (P < 0.001).

CONCLUSIONS

The incidence of hip subluxation in children with spinal cord injury increased with the injury duration. Younger children had immature hip development. Due to complete injury and flaccid muscle, lack of protection around the hip may lead to subluxation. Follow-up and prevention of hip subluxation need the joint effort of medical staff and families.

Hip Joint Instability After Surgery Performed Through the Surgical Dislocation Approach

Background

Safe surgical dislocation of the hip is a versatile approach to the hip joint with a low complication rate. Hip joint instability is a devastating complication with poor prognosis.

Methods

All hips treated surgically through the safe surgical dislocation approach were entered in a database and the complication of hip joint instability was studied prospectively from 2000 to 2021. Instability was diagnosed by intraoperative stress examination and on postoperative radiographs. The initial deformities treated, type of instability, presumed causes, treatment provided, response to the treatment, and final result were recorded as they happened during the course of the treatment. We considered patient's age, sex, body mass index (BMI), and initial diagnosis as risk factors. We evaluated the radiographs for femoral neck shortening, lack of greater trochanteric advancement, acetabular deformity, and incongruity of the hip joint. Anterior hip precautions were initiated in the middle of the study period.

Results

22/459 hips developed hip joint instability after surgical dislocation approach performed for hip preservation. Acetabular deficiency, coxa breva, coxa valga, posterior impingement, increased anteversion, lax soft tissues, medial thigh obesity and lack of postoperative precautions seemed to contribute to instability. 50% of the hips became normal. Chondrolysis and residual subluxation were common in the others.

Conclusion

Surgical dislocation approach disrupts the soft tissue restraints of the hip and joint stability depends on bony morphology, abductor muscle tension, and postoperative precautions. Several risk factors were subjective and speculative, but awareness of all the potential risk factors and prevention and treatment options should decrease this complication.

Level of Evidence

IV Case series.

Periacetabular osteotomy with or without femoral osteotomy for the treatment of hip subluxation in children and young adults with cerebral palsy

Background

This study is aimed to investigate retrospectively the radiographic and clinical outcomes in children and young adults with cerebral palsy (CP) undergoing periacetabular osteotomy (PAO) with or without femoral osteotomy (FO) for hip subluxation.

Methods

A consecutive cohort of twenty-one patients (23 hips) with symptomatic CP hip subluxation were treated with PAO with or without FO and reviewed retrospectively. Two patients (2 hips) were excluded due to insufficient follow-up and lost to follow-up, respectively. The Reimers migration percentage, lateral center-edge angle (LCEA), Sharp angle, neck-shaft angle (NSA), femoral anteversion (FNA), Gross Motor Function Classification System (GMFCS) and hip pain were assessed.

Results

Twenty-one hips (19 patients) with CP treated with PAO with or without FO were included. Five hips received PAO. Sixteen hips underwent PAO with FO. Mean age at surgery was 19 ± 6 and 15 ± 4 years for PAO and PAO plus FO, respectively. Mean follow-up was 44.0 ± 28.3 months for PAO and 41.5 ± 17.2 months for PAO + FO. All hips were painful before surgery and painless at final visits. The GMFCS improved by one level in 10 of 19 patients. There was significant increase in LCEA (p < 0.001) and decrease in the Reimer’s MP (p < 0.001), NSA (p < 0.001) and Tonnis angle(p < 0.001) postoperatively. Resubluxation occurred in 7 hips (30%) due to insufficient correction and loosening of fixation. Nervus cutaneus femoris lateralis was impaired in 4 patients after surgery. There was no avascular necrosis of the femoral head, resubluxation or infection.

Conclusion

PAO with or without FO can be effective for children and young adults with concomitant hip subluxation and CP.

Avascular necrosis after femoral neck fracture in children and adolescents: poor prognosis and risk factors

INTRODUCTION

Avascular necrosis (AVN) after femoral neck fracture (FNF) is a rare and severe paediatric condition, but only few studies described its prognosis and risk factors. The present study aimed to evaluate the outcomes and independent factors for poor prognosis of AVN after FNF in children and adolescents.

METHOD

This retrospective study included children and adolescents with AVN after FNF who received conservative treatment (CT group) or non-vascularized bone grafting (NVBG group) between 2000 and 2018. The primary outcomes were the risk of hip arthritis (Tönnis grade) and hip deformity risk (Stulberg classification). All patients were followed for at least two years to assess AVN progression.

RESULTS

Study included 81 patients. In the CT group, 23/43 patients (53.4%) developed hip arthritis, and 24/43 patients (55.8%) showed hip deformity. In the NVBG group, 23/38 patients (60.5%) developed hip arthritis, and 34/38 patients (89.5%) had a hip deformity. The multivariable analysis indicated that NVBG surgery had no significant effect on the outcomes. Post-treatment femoral head collapse (P = 0.05, OR = 3.80, 95% CI = 1.01-14.29) and post-treatment hip subluxation (P = 0.01, OR = 2.85, 95% CI = 2.31-129.56) were independent risk factors for severe hip arthritis. Post-treatment femoral head collapse (P < 0.01, OR = 7.64, 95% CI = 3.23-18.04) and pre-treatment hip subluxation (P = 0.02, OR = 7.33, 95% CI = 1.44-37.41) were independent risk factors for severe hip deformity.

CONCLUSION

Neither CT nor NVBG have demonstrated superiority regarding long-term outcomes in patients with AVN after FNF. Upon the disease progression to severe collapse with subluxation and severe arthritis, further hip preservation attempts could be futile.

Soft tissue surgery as an initial treatment for hip displacement in spastic cerebral palsy

Objective: To use the measurement of migration percentage (MP) to evaluate the long-term radiographic results of soft tissue surgery as the first treatment for hip displacement in spastic bilateral cerebral palsy. A secondary objective was to identify predictive factors of stability (i.e., less than 30% of MP in the long term), after surgical correction. Methods: In this longitudinal cohort study, we reviewed the electronic medical records and radiographs of all consecutive patients with cerebral palsy operated for the correction of hip displacement between 1984 and 2013 in a referral orthopedic public hospital in Brazil. Patients were included if they had received, as the first surgical procedure, soft-tissue release. All surgeries were bilateral and symmetrical. We used the available radiographs to evaluate the migration percentage (MP), acetabular index (AI), pelvic obliquity (PO) angle, head-shaft angle (HSA), congruence and femoral head sphericity, and function using the GMFCS (Gross Motor Function Classification System). Results: we included 93 patients, all operated before being 12 years old, with follow-up of 10 years in average, 73 (78%) of them with good results (MP < 30%). We found association between preoperative MP ≤ 40%, AI ≤ 25°, and postoperative symmetry with good results, with a cut-off value of 38% of MP and 27° of acetabular index being predictive. Discussion: The role of soft tissue releases remains controversial owing to small sample sizes, heterogeneity, variety range of ages, definitions used for outcome, and lack of statistical quality. Our results were better in combined tenotomies, in diparetic patients aged more than six years, and in patients with lower initial values of MP and AI. Radiographic variables had good correlation with each other and association with results, with cut-off values for MP and AI PRE.

Neglected subluxation of the hip after trauma: A case report

Introduction

In children, the pelvis contains a large amount of cartilage components; therefore, when traumatic hip dislocation spontaneously reduces, it can be impossible to see on X-ray or computed tomography (CT) images in some cases, which can delay its detection.

Case presentation

We report the case of a 10-year-old boy who was injured by being hit by a car while walking. Upon diagnosis of pelvic ring fracture, the patient received conservative treatment. Seven months after injury, the patient was referred to our department with the chief complaint of limping.

Diagnosis

Marked limitation was observed in the left hip with extension of −40°, abduction of 10°, and internal rotation of 20°. X-ray revealed narrowing of the left hip joint space, with deformity of the femoral head, obturator foramen narrowing, and the break in the Shenton line. CT revealed proximal dislocation of the posterior acetabular wall and posterior subluxation of the femoral head. Magnetic resonance imaging (MRI) revealed necrosis of the femoral head.

Intervention

Operation was performed with soft tissue dissection, varus-extension-internal rotation femoral osteotomy, greater trochanteric epiphysiodesis, and pelvic osteotomy (incomplete periacetabular osteotomy: IPO). After operation, complete paralysis of the sciatic nerve was observed.

Outcomes

At 1 year after operation, the patient's limited range of motion (ROM) and femoral head necrosis had improved. The sciatic nerve paralysis had fully recovered.

Conclusion

If hip extension, abduction, and internal rotation are limited and X-ray reveals a break in the Shenton line., subluxation of the hip should be suspected.

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Pelvic fractures in children.

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Limited ROM in hip.

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Break in Shenton line.

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Subluxation of hip.

Hip Dysplasia: Clinical Signs and Physical Examination Findings

Hip dysplasia is a common developmental disorder of the dog, consisting of varying degrees of hip laxity, progressive remodeling of the structures of the hip, and subsequent development of osteoarthritis. It is a juvenile-onset condition, with clinical signs often first evident at 4 to 12 months of age. A tentative diagnosis of hip dysplasia can be made based on signalment, history, and physical examination findings. The Ortolani test is a valuable tool for identifying juvenile dogs affected with this condition. Further diagnostics can then be prioritized, contributing to prompt diagnosis and appropriate treatment.

Evaluation and treatment of developmental hip dysplasia in the newborn and infant

Developmental dysplasia of the hip (DDH) encompasses a spectrum of physical and imaging findings. The child's hip will not develop normally if it remains unstable and anatomically abnormal by walking age. Therefore, careful physical examination of all infants to diagnosis and treat significant DDH is critical to provide the best possible functional outcome. Regardless of the practice setting, all health professionals who care for newborns and infants should be trained to evaluate the infant hip for instability and to provide appropriate and early conservative treatment or referral.

Magnetic resonance imaging in traumatic hip subluxation

Athletic traumatic hip subluxations are rare. Classic radiographic features have been well described. This case highlights the potential pitfalls of immediate magnetic resonance imaging. Femoral head contusions and acetabular rim fractures are common associated findings usually apparent with magnetic resonance imaging (MRI). However, in this case an MRI done 3 hours post injury failed to show any edema in either location, making the appearance of these findings on subsequent MRIs difficult to interpret. An acute MRI more than 48 hours post injury may have been more helpful.