Normal Percentile Reference Curves and Correlation of Acetabular Index and Acetabular Depth Ratio in Children.

BACKGROUND: Radiographic surveillance of the hip is vital in the diagnosis and treatment of developmental dysplasia of the hip (DDH) in children. The acetabular index (AI) and the acetabular depth ratio (ADR) are radiographic parameters for evaluation of acetabular morphology. Normal reference curves for these parameters that allow for serial evaluation of acetabular development in a manner that is independent of age are necessary and clinically useful. The purpose of this study was (1) to establish normal values of AI and ADR in the normally developing pediatric hip up to age 14, (2) to generate percentile reference curves of both parameters, (3) to determine the extent of correlation between AI and ADR, and (4) to assess intrarater and interrater reliability of AI measurement. METHODS: We identified 1734 patients who underwent anterior-posterior pelvic radiography between 2004 and 2014. A total of 1152 patients (age range, 0.15 to 13.97 y; 2304 hips) were identified as radiographically normal in the radiology report, signed by the attending pediatric radiologist on the basis of the absence of structural deformity of the hip and previously established reference values for DDH assessment. A review of the medical records confirmed that patients had no diagnosis of DDH or any other orthopaedic hip pathology. The AI and ADR were measured in all radiographs. Normal values and fully parametric percentile curves were generated from birth to skeletal maturity. Correlation between AI and ADR was assessed using linear regression analysis. RESULTS: Normal AI decreased, and ADR increased, with age. Percentile curves were generated for AI and ADR. Using the provided equations, measured values can be converted to age-appropriate percentile and Z-score. The 2 parameters exhibited strong correlation (Pearson correlation=-0.789, P<0.001). For every unit increase in ADR, AI decreased by 0.94 degrees. CONCLUSIONS: We present updated normative values of AI that expand up to age 14, and novel reference values for ADR. The reference curves allow for the easy conversion of measured values to percentile and Z-score. Using the presented method during surveillance of the pathologic hip, change in acetabular development can now be assessed in a manner that is independent of age and the natural development of the acetabulum. LEVEL OF EVIDENCE: Level IV-case series.

Outcomes of Isolated Varus Derotational Osteotomy in Children With Cerebral Palsy Hip Dysplasia and Predictors of Resubluxation.

BACKGROUND: The appropriate intervention for hip subluxation or dislocation in children affected by cerebral palsy (CP) remains controversial. The purpose of this retrospective study was to report radiographic and clinical outcomes following isolated femoral varus derotational osteotomy (VDRO) in children with CP hip dysplasia. Risk factors for resubluxation and avascular necrosis (AVN) were also examined. METHODS: A cohort of 100 patients (199 hips) with CP treated with isolated VDRO between 2003 and 2009 was reviewed. All but 1 patient received bilateral surgery. Patients were followed for an average of 5.4 years (range, 1.03 to 10.20 y). Anteroposterior pelvic radiographs were used to assess migration percentage (MP), Shenton's line, and presence of AVN. Resubluxation was defined as a postoperative break in Shenton's line. Radiographic outcomes and risk analysis was performed in the 91 subjects (179 hips) with radiographic follow-up >1 year. RESULTS: Significant improvement was observed in MP, and all hips had a reconstituted Shenton's line following surgery. Over the course of follow-up, 16% of hips were noted to have a repeat break in Shenton's line. Univariate risk analysis showed preoperative MP, Gross Motor Function Classification System (GMFCS) level, and age at surgery were risk factors for a recurrent line break. Preoperative MP and GMFCS level were found to be predictors of resubluxation in multivariate analysis. AVN was detected in 10 hips (5.7%). GMFCS level V patients were more at risk for resubluxation, but less at risk for AVN when compared with ambulatory (GMFCS I/II/II) patients and GMFCS level IV patients. CONCLUSIONS: Performing a VDRO without additional procedures provided a stable and concentrically reduced hip joint in this population of children with CP. Attention should be paid to initial ambulatory status during the postoperative period. Concomitant procedures such as pelvic osteotomy should be considered for patients of GMFCS level IV and V, as these patients were more at risk for recurrent subluxation. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Acetabular Remodeling After a Varus Derotational Osteotomy in Children With Cerebral Palsy.

BACKGROUND: The optimal surgical intervention for hip dysplasia in cerebral palsy (CP) is controversial. The purpose of this study was to determine (1) whether an isolated varus derotation osteotomy (VDRO) for the treatment of CP hip dysplasia allows for acetabular remodeling as measured by acetabular depth ratio (ADR), (2) the predictive factors for acetabular remodeling after an isolated VDRO for the treatment of CP hip dysplasia, and (3) to establish the normal ADR in typical children for comparison. METHODS: Eighty-seven CP patients (174 hips) treated with an isolated VDRO between 2003 and 2009 were retrospectively reviewed. The average age at surgery was 4.6 years (range, 2.4 to 10.6 y) and the average follow-up period was 5.1 years (range, 1.1 to 9.9 y). Acetabular remodeling was assessed on radiographs by the ADR. Changes in preoperative and postoperative ADR were analyzed using linear mixed-effects models. Patients were divided into 2 different groups for the postoperative ADR analysis: Gross Motor Function Classification System (GMFCS) levels I, II, and III compared with GMFCS levels IV and V. The progression of ADR versus age was determined in a set of 917 normal children (1834 hips) for comparison. RESULTS: There was a statistically significant increase (improvement) in ADR postsurgically for the collective CP set (P<0.001) and for both GMFCS categories (I/II/III, IV/V: P<0.001). GMFCS level, sex, and intraoperative neck shaft angle (NSA) were determined to be significant predictors for postoperative ADR improvement. GMFCS level was the most significant predictor for an increase in ADR after surgery (P<0.001). Less improvement in ADR was observed in patients of GMFCS levels IV and V compared with patients of GMFCS levels I, II, and III (P<0.001). A lower intraoperative NSA resulted in greater postoperative increase in ADR (P<0.05). CONCLUSIONS: Overall, isolated VDRO allowed for acetabular remodeling in CP hip dysplasia. Acetabular remodeling was increased in patients of GMFCS levels I, II, and III compared with patients of GMFCS levels IV and V. Increased varization at the time of VDRO improved acetabular remodeling. This study recommends considering GMFCS level and intraoperative NSA during surgical planning for CP hip dysplasia.

Rate of Correction and Recurrence of Ankle Valgus in Children Using a Transphyseal Medial Malleolar Screw.

BACKGROUND: Transphyseal medial malleolar screw (TMMS) hemiepiphysiodesis is an effective treatment for ankle valgus in children. There is limited evidence on the effect of age and diagnosis on the rate of correction as well as the deformity recurrence after screw removal. The purpose of this study was to determine (1) the rate of correction of ankle valgus after hemiepiphysiodesis using a TMMS, (2) the effects of clinical diagnosis and age at surgery on the rate of correction, and (3) the rate of valgus recurrence after TMMS removal. METHODS: In this retrospective study we included 16 male and 21 female patients (63 ankles) with an average age at surgery of 11.0 years (range, 5.4 to 14.8 y) who underwent TMMS hemiepiphysiodesis for the treatment of ankle valgus. There was a mean radiographic follow-up of 1.6 years (range, 0.4 to 4.9 y) before screw removal. For subjects who received screw removal (43 ankles), the average time from insertion to removal of the screw was 1.4 years (range, 0.4 to 5.2 y). Valgus deformity was assessed on anteroposterior ankle radiographs by measurement of tibiotalar angle. Linear mixed effects models were used to determine rates of correction and valgus recurrence. RESULTS: The average rate of correction in tibiotalar angle was 0.37±0.04 degrees per month (P<0.001). Clinical diagnosis and age at surgery significantly affected the amount of postoperative correction in tibiotalar angle (P<0.05). Eighteen of 22 ankles (81.8%) demonstrated recurrence of ankle valgus after screw removal. The average recurrence rate in patients who underwent screw removal was 0.28±0.08 degrees per month (22 ankles, P=0.002). CONCLUSIONS: This study supports the effectiveness of the TMMS hemiepiphysiodesis for treating pediatric ankle valgus, but the effects of additional skeletal growth should be considered as the ankle may rebound into valgus after correction and screw removal. The results from this study can help with surgical planning to predict the amount of correction that may be achieved depending on underlying diagnosis and age at surgery. LEVEL OF EVIDENCE: Level IV-retrospective study.

Radiographic and plantar pressure assessment of pes planovalgus severity in children with cerebral palsy.

BACKGROUND: Pes planovalgus is common in children with cerebral palsy. Although severity influences treatment, there still lacks standard clinical measurements to objectively quantify pes planovalgus in this population. The comparison of pedobarographic data and radiographic measurements to clinical evaluation has not been reported in this population. METHODS: 395  feet were identified from a population of ambulatory pediatric patients with cerebral palsy. Each patient initially underwent clinical evaluation by an experienced physical therapist who classified feet as: 136 controls, 116 mild, 100 moderate, and 43 severe pes planovalgus. Quantitative measurements were then calculated from antero-posterior and lateral radiographs of the foot. Pedobarographic analysis included the arch index, center of pressure index, and a newly defined medial index. FINDINGS: A multivariate analysis was performed on the radiographic and pedobarographic measurements collected. It identified seven variables that improved objective classification of pes planovalgus severity when utilized together. These include the foot progression angle, initial contact force, arch index, medial index, antero-posterior talonavicular coverage, lateral calcaneal pitch and lateral Meary's angle. While the lateral calcaneal pitch angle statistically differed amongst all severity classes, no pedobarographic value statistically differed between all severity classes. INTERPRETATION: Overall, the combination of radiographic and pedobarographic measurements provides valuable information for objectively classifying severity of pes planovalgus in children with cerebral palsy by utilizing these values together rather than independently. In a clinical setting, radiographs and pedobarographic data may be obtained to enhance assessment of severity and guide treatment.

The role of gait analysis in treating gait abnormalities in cerebral palsy.

Individuals with cerebral palsy (CP) cannot take a normal activity like walking for granted. CP is the most common pediatric neurologic disorder, with an incidence of 3.6 per 1000 live births. The current trend in the treatment of individuals with CP is to perform a thorough evaluation including a complete patient history from birth to present, a comprehensive physical examination, appropriate radiographs, consultation with other medical specialists, and analysis of gait.