Normal development of the hip: a geometrical analysis based on planimetric radiography

Unlike Acetabular Anteversion, Femoral Anteversion Is Not Associated with the Hip Coronal Morphotype: An Anatomic Basis for a New Hip Morphotype Classification at Total Hip Arthroplasty

BACKGROUND

Most femoral stem designs used in total hip arthroplasty (THA) take into account the proximal femoral morphotype in terms of lateralization and neck-shaft angle (NSA) but not version. The objective of this study was to analyze the acetabular anteversion and femoral anteversion (FA) values in a large cohort according to the 3-dimensional (3D) morphotype of the proximal femur. Our hypothesis was that FA is an anatomic parameter independent of the coronal morphotype (varus, neutral, valgus).

METHODS

A retrospective study based on prospectively collected data included all patients who underwent, from January 2009 to December 2021, a THA planned on the basis of a low-dose computed tomographic (CT) scan 3D. The anatomic acetabular anteversion was calculated in the anterior pelvic plane. The 3D volume models were used to measure the NSA and the FA. We used a multivariable linear regression model to assess the relationship between the NSA and the other hip parameters.

RESULTS

The study included 849 consecutive patients (430 women and 419 men), with a mean age of 62 ± 15 years and a mean body mass index of 26.8 ± 5.7 kg/m2. The etiology was primary osteoarthritis in 616 patients, osteonecrosis in 141 patients, and dysplasia in 92 patients. The mean NSA was 129° ± 7°. The femoral morphotype was vara in 112 cases and valga in 105 cases. Acetabular anteversion was significantly lower in the vara group (mean, 21° ± 9°) and higher in the valga group (mean, 26° ± 9°) compared with the neutral group (mean, 24° ± 8°) (p < 0.001). The FA did not vary significantly according to the femoral morphotype (mean, 20° ± 12°; p = 0.3), with no significant association found between the NSA and FA (β = -0.004 [95% confidence interval, -0.5 to 0.05]; p = 0.8).

CONCLUSIONS

The FA was not associated with the NSA. A hip morphotype classification combining the NSA and FA is presented for use in guiding preoperative planning in THA. Customized patient-specific stems may be of interest in some morphotypes to accurately restore the hip anatomy.

LEVEL OF EVIDENCE

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

Morphologic Development of the Posterior Sloping Angle of the Proximal Femoral Epiphysis in Children: What Is the Peak Risk Age for Slipping?

OBJECTIVE

The purpose of this study was to describe the developmental patterns of the posterior sloping angle (PSA) of the proximal femoral epiphyseal growth plate (PFEP) in a cohort of healthy Chinese children aged 5 to 14 years.

METHODS

Pelvic frog-leg lateral radiographs of 400 healthy children (n=800 hips) were retrospectively analyzed. The cohort included 215 males and 185 females with a mean age of 9.5 years (5 to 14). PSA measurements of the PFEP were obtained bilaterally from frog leg lateral radiographs. Subjects were equally divided into 10 subgroups of 40 patients each (80 hips per group) based on age, starting at 5 years of age; in addition, sex and lateral differences, as well as age-related developmental patterns were analyzed.

RESULTS

The PSA was -2.6±3.1 degrees at 5 years of age, indicating mild anterior inclination of the femoral epiphysis. It increased to 6.2±4.6 degrees at 11 years of age, decreased to 3.9±4.3 degrees at 12 years of age, and then stabilized until 14 years of age. Before 11 years of age, there was no significant sex difference in PSA values, whereas, after 11 years of age, males had a PSA of 5.8±4.3 degrees compared with 3.7±5.0 degrees in females ( P <0.001), with the former showing an average increase of ~2 to 3 degrees more. In addition, the left PSA was ~2 degrees greater than the right PSA in both men and women ( P <0.001).

CONCLUSIONS

Before puberty, PSA gradually increased with age, peaking at 11 years of age, followed by a slight decline and then stabilization. After the age of 11 years, males had higher PSA levels than females, with the PSA of the left side being significantly higher than that of the right side. Understanding these developmental patterns may aid in the assessment and monitoring of adolescent PFEP disorders.

LEVEL OF EVIDENCE

Level III-diagnostic studies.

Effects of different pelvic osteotomies on acetabular morphology in developmental dysplasia of hip in children

Developmental dysplasia of hip seriously affects the health of children, and pelvic osteotomy is an important part of surgical treatment. Improving the shape of the acetabulum, preventing or delaying the progression of osteoarthritis is the ultimate goal of pelvic osteotomies. Re-directional osteotomies, reshaping osteotomies and salvage osteotomies are the three most common types of pelvic osteotomy. The influence of different pelvic osteotomy on acetabular morphology is different, and the acetabular morphology after osteotomy is closely related to the prognosis of the patients. But there lacks comparison of acetabular morphology between different pelvic osteotomies, on the basis of retrospective analysis and measurable imaging indicators, this study predicted the acetabular shape after developmental dysplasia of the hip pelvic osteotomy in order to help clinicians make reasonable and correct decisions and improve the planning and performance of pelvic osteotomy.

Reliability and sensitivity of radiographic measures of hip dysplasia in childhood Charcot-Marie-Tooth disease

BACKGROUND

Hip dysplasia is a lack of femoral head coverage and disruption of hip and acetabular alignment and congruency, with severity ranging from mild subluxation in nascent at-risk hips to complete dislocation. Presentation of hip dysplasia in neuromuscular conditions can be sub-clinical or associated with a limp with or without hip pain, abductor and flexor weakness and reduced hip range of motion. Untreated hip dysplasia leads to early onset osteoarthritis requiring hip arthroplasty in early adulthood. Hip dysplasia occurs in 6-20% of children with Charcot-Marie-Tooth disease, however little is known about the reliability and sensitivity of detection on plain film pelvic radiographs.

METHODS

14 common measures of hip dysplasia on anteroposterior pelvis radiographs were independently assessed by 2 orthopaedic specialists in 30 ambulant children with Charcot-Marie-Tooth disease. Hip health was also categorised based on clinical impression to assess the sensitivity of radiographic measures to identify hip dysplasia status.

RESULTS

8 measures (acetabular index, head width, lateral centre-edge angle, lateral uncoverage, medial joint width, migration percentage, neck shaft angle, triradiate status) exhibited 'excellent' reliability between clinical evaluators. 5 of the 30 patients (17%) were identified as having nascent hip dysplasia. Reliable radiographic measures that significantly distinguished between nascent hip dysplasia and healthy hips were acetabular index, lateral centre edge angle, medial joint width and migration percentage.

CONCLUSIONS

We have identified a subset of reliable and sensitive radiographic hip measures in children with Charcot-Marie-Tooth disease to prioritise during hip screening to mitigate the deleterious effects of hip dysplasia, pain and disability in adulthood.

Debilitating hip degeneration in trichothiodystrophy: Association with ERCC2/XPD mutations, osteosclerosis, osteopenia, coxa valga, contractures, and osteonecrosis

Trichothiodystrophy (TTD) is a rare, autosomal recessive, multisystem disorder of DNA repair and transcription with developmental delay and abnormalities in brain, eye, skin, nervous, and musculoskeletal systems. We followed a cohort of 37 patients with TTD at the National Institutes of Health (NIH) from 2001 to 2019 with a median age at last observation of 12 years (range 2-36). Some children with TTD developed rapidly debilitating hip degeneration (DHD): a distinctive pattern of hip pain, inability to walk, and avascular necrosis on imaging. Ten (27%) of the 37 patients had DHD at median age 8 years (range 5-12), followed by onset of imaging findings at median age 9 years (range 5-13). All 10 had mutations in the ERCC2/XPD gene. In 7 of the 10 affected patients, DHD rapidly became bilateral. DHD was associated with coxa valga, central osteosclerosis with peripheral osteopenia of the skeleton, and contractures/tightness of the lower limbs. Except for one patient, surgical interventions were generally not effective at preventing DHD. Four patients with DHD died at a median age of 11 years (range 9-15). TTD patients with ERCC2/XPD gene mutations have a high risk of musculoskeletal abnormalities and DHD leading to poor outcomes. Monitoring by history, physical examination, imaging, and by physical medicine and rehabilitation specialists may be warranted.

Is there a persistent capital femoral epiphysis growth after screw fixation for slipped capital femoral epiphysis?

Femoral neck screwing during child development is controversial. The objective of this study was to evaluate the residual growth of the capital femoral physis after screw fixation. This retrospective study included children aged younger than 12 years treated for slipped capital femoral epiphysis (SCFE) with a single percutaneous partially threaded cannulated screw. The children were followed up for at least 1 year. Some patients also underwent prophylactic contralateral screwing. Preoperative, immediate postoperative and final follow-up X-rays were evaluated to determine the degree of slippage, pin–joint ratio (PJR), neck–pin ratio (NPR), number of threads crossing the physis, neck–shaft angle (NSA), screw–physis angle and screw position in the physis. We included 17 patients (29 hips: 18 SCFE and 11 prophylactic) with a mean age of 10.1 years (range: 7.1–11.9 years) at the time of surgery. Significant evolution of radiological growth parameters of the proximal femoral physis was noted during a mean follow-up of 2.4 years (range: 1–4.3 years). The mean PJR significantly decreased from 7.3 to 6.0, the mean NPR significantly decreased from 106 to 96 and the mean number of threads beyond the physis decreased from 3.3 to 1.8. The mean NSA decreased by 6.5°, from 139° to 132.5°. Persistent capital femoral epiphysis growth occurs after screw fixation. The NSA significantly decreases over time but remains within the physiological limits.

Level of evidence: IV (case series)

Effect of positioning error on the Hilgenreiner epiphyseal angle and the head-shaft angle compared to the femoral neck-shaft angle in children with cerebral palsy

Children with cerebral palsy (CP) often have changes in proximal femoral geometry. Neck-shaft angle (NSA), Hilgenreiner epiphyseal angle (HEA) and head-shaft angle (HSA) are used to measure these changes. The impact of femoral rotation on HEA/HSA and of ab/adduction on HEA/HSA/NSA is not well known. This study aimed to determine and compare the effect of rotation, ab/adduction and flexion/extension on HEA/HSA/NSA. Radiographic measurements from 384 patients with Gross Motor Function Classification System (GMFCS) levels I-V were utilized. NSA/HSA for affected hips were used with femoral anteversion averages to create three-dimensional models of 694 hips in children with CP. Each hip was rotated, ab/adducted and flexed/extended to simulate malpositioning. HEA/HSA/NSA of each model were measured in each joint position, and differences from correct positioning were determined. Mean HEA error at 20° of internal/external rotations were -0.60°/3.17°, respectively, with the NSA error of -6.56°/9.94° and the HSA error of -3.69°/1.21°. Each degree of ab/adduction added 1° of the HEA error, with no NSA/HSA error. NSA was most sensitive to flexion. Error for all measures increased with increasing GMFCS level. HEA/HSA were minimally impacted by rotation. NSA error was much higher than HEA/HSA in internal rotation and flexion whereas HEA was sensitive to changes in ab/adduction. Given abduction is more easily detectable on imaging than rotation, HEA may be less affected by positioning errors that are common with children with CP than NSA. HSA was least affected by position changes. HEA/HSA could be robust, complementary measures of hip deformities in children with CP.

Pathophysiology of Hip Disorders in Patients with Mucopolysaccharidosis IVA

Patients with mucopolysaccharidoses IVA (MPS IVA) have a progressive accumulation of the specific glycosaminoglycans (GAGs): chondroitin-6-sulfate (C6S) and keratan sulfate (KS), leading to the degeneration of the cartilage matrix and its connective tissue perturbing the regular microarchitecture of cartilage and successively distorting bone ossification and growth. Impaired cartilage quality and poor bone mineralization lead to serious hip disorders in MPS IVA patients. Although hip dysplasia is seen widely in musculoskeletal abnormality of this disorder, the pathophysiology of the hip bone and cartilage morphology in these patients remains unclear. Until now, no systemic study of the hip joints in MPS IVA has been reported by using the combined images of plain film radiographs (PFR) and Magnetic Resonance Imaging (MRI). This study aimed to assess the bony and cartilaginous features of hip joints and to explore the potentially related factors of femoral head osteonecrosis (FHN) and hip subluxation/dislocation in patients with MPS IVA. Hip joints in MPS IVA patients were retrospectively reviewed, based on the findings of PFR and MRI data from 2014 to 2019. Demographic information was also collected and analyzed with imaging measurements. A total of 19 patients (eight boys and 11 girls) were recruited, and 38 hip joints in these patients were examined. Eleven patients (57.9%) had FHN. FHN patients were statistically compared with those without FHN. Correlations between cartilaginous femoral head coverage (CFHC) and acetabular index (AI), cartilaginous AI (CAI), or neck-shaft angle (NSA) were investigated in patients with hip subluxation or dislocation. The greater cartilaginous coverage of the hips than their osseous inherency was observed. Significant correlation was observed between CFHC and AI (r =-0.351, p = 0.049) or CAI (r =-0.381, p = 0.032). Severe subluxations or dislocations were more likely to be present in those with more dysplastic bony and cartilaginous hips. In conclusion, our study provides the first systemic description of bony and cartilaginous characteristics in the hip morphology of MPS IVA patients. We have demonstrated that plain radiography alone leads to a misunderstanding of hip morphology and that MRI measurements with PFR are an essential tool to evaluate the 'true' characterization of hips for MPS IVA patients.

Analysis of Proximal Femoral Parameters in Adolescent Idiopathic Scoliosis

BACKGROUND

Assessment of the proximal femoral parameters in adolescent idiopathic scoliosis using three-dimensional radiological image reconstructions may allow better characterization than conventional techniques.

METHODS

EOS 3D reconstructions of spines and femurs of 320 scoliotic patients (10-18 years old) and 350 control children lacking spinal abnormality were performed and 6 proximal femoral parameters measured.

RESULTS

Individuals with adolescent idiopathic scoliosis showed a small but statistically significant decrease in neck shaft angle (average difference=2.58°) and a higher (0.22°) femoral mechanical axis-femoral shaft angle. When the two sides were compared based on curve direction, greater changes in the neck shaft angle and femoral mechanical axis-femoral shaft angle were found on the side of the convexity.

CONCLUSIONS

Patients with adolescent idiopathic scoliosis were found to have a small but significantly lower neck shaft angle and higher femoral mechanical axis-femoral shaft angle, which related to the curve direction. This is postulated to be due to mechanical compensation for altered balance and centre of gravity associated with a scoliosis deformity, although the observed difference likely has negligible clinical effect.

Age at Onset of Walking in Infancy Is Associated With Hip Shape in Early Old Age

Bones' shapes and structures adapt to the muscle and reaction forces they experience during everyday movements. Onset of independent walking, at approximately 12 months, represents the first postnatal exposure of the lower limbs to the large forces associated with bipedal movements; accordingly, earlier walking is associated with greater bone strength. However, associations between early life loading and joint shape have not been explored. We therefore examined associations between walking age and hip shape at age 60 to 64 years in 1423 individuals (740 women) from the MRC National Survey of Health and Development, a nationally representative British birth cohort. Walking age in months was obtained from maternal interview at age 2 years. Ten modes of variation in hip shape (HM1 to HM10), described by statistical shape models, were ascertained from DXA images. In sex-adjusted analyses, earlier walking age was associated with higher HM1 and HM7 scores; these associations were maintained after further adjustment for height, body composition, and socioeconomic position. Earlier walking was also associated with lower HM2 scores in women only, and lower HM4 scores in men only. Taken together, this suggests that earlier walkers have proportionately larger (HM4) and flatter (HM1, HM4) femoral heads, wider (HM1, HM4, HM7) and flatter (HM1, HM7) femoral necks, a smaller neck-shaft angle (HM1, HM4), anteversion (HM2, HM7), and early development of osteophytes (HM1). These results suggest that age at onset of walking in infancy is associated with variations in hip shape in older age. Early walkers have a larger femoral head and neck and smaller neck-shaft angle; these features are associated with reduced hip fracture risk, but also represent an osteoarthritic-like phenotype. Unlike results of previous studies of walking age and bone mass, associations in this study were not affected by adjustment for lean mass, suggesting that associations may relate directly to skeletal loading in early life when joint shape changes rapidly. © 2018 American Society for Bone and Mineral Research.

3-dimensional metrics of proximal femoral shape deformities in Legg-Calvé-Perthes disease and slipped capital femoral epiphysis

Legg-Calvé-Perthes disease (LCPD) and slipped capital femoral epiphysis (SCFE) are two common pediatric hip disorders that affect the 3-dimensional shape and function of the proximal femur. This study applied the principles of continuum mechanics to statistical shape modeling (SSM) and determined 3-D metrics for the evaluation of shape deformations in normal growth, LCPD, and SCFE. CT scans were obtained from 32 patients with asymptomatic, LCPD, and SCFE hips ((0.5-0.9 mm)² in-plane resolution, 0.63 mm slice thickness). SSM was performed on segmented proximal femoral surfaces, and shape deformations were described by surface displacement, strain, and growth plate angle metrics. Asymptomatic normal femurs underwent coordinated, growth-associated surface displacements and anisotropic strains that were site-specific and highest at the greater trochanter. After size- and age-based shape adjustment, LCPD femurs exhibited large displacements and surface strains in the femoral head and neck, with associated changes in femoral head growth plate angles. Mild SCFE femurs had contracted femoral neck surfaces, and surface displacements in all regions tended to increase with severity of slip. The results of this paper provide new 3-D metrics for characterizing the shape and biomechanics of the proximal femur. Statement of Clinical Significance: Quantitative 3-D metrics of shape may be useful for understanding and monitoring disease progression, identifying target regions for shape modulation therapies, and objectively evaluating the success of such therapies. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1526-1535, 2018.

PREDICT-CP: study protocol of implementation of comprehensive surveillance to predict outcomes for school-aged children with cerebral palsy

OBJECTIVES

Cerebral palsy (CP) remains the world's most common childhood physical disability with total annual costs of care and lost well-being of $A3.87b. The PREDICT-CP (NHMRC 1077257 Partnership Project: Comprehensive surveillance to PREDICT outcomes for school age children with CP) study will investigate the influence of brain structure, body composition, dietary intake, oropharyngeal function, habitual physical activity, musculoskeletal development (hip status, bone health) and muscle performance on motor attainment, cognition, executive function, communication, participation, quality of life and related health resource use costs. The PREDICT-CP cohort provides further follow-up at 8-12 years of two overlapping preschool-age cohorts examined from 1.5 to 5 years (NHMRC 465128 motor and brain development; NHMRC 569605 growth, nutrition and physical activity).

METHODS AND ANALYSES

This population-based cohort study undertakes state-wide surveillance of 245 children with CP born in Queensland (birth years 2006-2009). Children will be classified for Gross Motor Function Classification System; Manual Ability Classification System, Communication Function Classification System and Eating and Drinking Ability Classification System. Outcomes include gross motor function, musculoskeletal development (hip displacement, spasticity, muscle contracture), upper limb function, communication difficulties, oropharyngeal dysphagia, dietary intake and body composition, participation, parent-reported and child-reported quality of life and medical and allied health resource use. These detailed phenotypical data will be compared with brain macrostructure and microstructure using 3 Tesla MRI (3T MRI). Relationships between brain lesion severity and outcomes will be analysed using multilevel mixed-effects models.

ETHICS AND DISSEMINATION

The PREDICT-CP protocol is a prospectively registered and ethically accepted study protocol. The study combines data at 1.5-5 then 8-12 years of direct clinical assessment to enable prediction of outcomes and healthcare needs essential for tailoring interventions (eg, rehabilitation, orthopaedic surgery and nutritional supplements) and the projected healthcare utilisation.

TRIAL REGISTRATION NUMBER

ACTRN: 12616001488493.

Dynamic long leg casting fixation for treating 12- to 18-month-old infants with developmental dysplasia of the hip

Objective To evaluate the effect of dynamic long leg casting in paediatric patients with developmental dysplasia of hip (DDH) diagnosed at 12-18 months. Methods The adductor tenotomy, closed reduction, and dynamic long leg casting method was adopted to treat paediatric patients with DDH. The hips were divided into four groups according to the Tonnis radiographic dislocation classification. Groups were also classified according to the baseline acetabular index (AI): 30°-35°, 36°-40°, and > 40°. The outcomes of the reductions were evaluated according to McKay's hip function criteria and Severin's radiological criteria. Results A total of 246 patients (339 hips) had complete follow-up data. After 3 months of orthosis fixation, the results were satisfactory in 264 hips (77.88%). Hip function was rated as 'excellent' or 'good' in 43 of 51 (84.31%) Tonnis type 1 hips, 125 of 155 (80.65%) type 2 hips, 70 of 90 (77.78%) type 3 hips, and 34 of 43 (79.07%) type 4 hips. The higher the baseline AI, the lower the rates of 'excellent' and 'good' hip function. Favourable radiological results (Severin types I and II) were found in 266 of 339 (78.47) hips. Conclusions Dynamic long leg casting is an effective method for treating patients with DDH aged 12-18 months at diagnosis.

Normal radiological unossified hip joint space and femoral head size development during growth in 675 children and adolescents

Evaluation of hip joint space width during child growth is important to aid in the early diagnosis of hip pathology in children. We established reference values for hip joint space and femoral head size for each age. Hip joint space development during growth was retrospectively investigated medial and cranial in 1350 hip joints of children using standard anteroposterior supine plain pelvic radiographs. Maximum capital femoral epiphysis diameter and femoral radii were further more investigated. Hip joint space values show a slow decline during growth. Joint space was statistically significantly (p < 0.006) larger in boys than girls. Our hip joint space measurements on supine subjects seem slightly larger than those reported by Hughes on standing subjects. Evaluation of the femoral head diameter and the radii showed a size curve quite parallel to the known body growth charts. Radii medial and perpendicular to the physis are not statistically significantly different. We recommend to compare measurements of hip joint space at two locations to age dependent charts using the same imaging technique. During growth, a divergence in femoral head size from the expected values or loss of the spherical shape should raise the question of hip disorder. Clin. Anat. 30:267-275, 2017. © 2016 Wiley Periodicals, Inc.

Ontogeny of the male femur: Geometric morphometric analysis applied to a contemporary Spanish population

OBJECTIVE

To describe the morphological changes of the male femur during the adolescent growth spurt and to compare the pattern obtained with that reported previously for females.

MATERIAL AND METHODS

Two hundred and forty males from a Spanish population aged between 9 and 16 years were analysed, based on telemetries. Size and shape variation of the femur was quantified by 22 2D-landmarks and analysed using geometric morphometric methods. Likewise, the variation of neck-shaft and bicondylar angles were also determined and evaluated by Student's t-test. Sexual differences were analysed by comparing results here obtained on boys with those corresponding to girls reported in a previous study.

RESULTS

In males, both size and shape varied significantly with age, with males having larger dimensions than females. In general terms, these changes are generally characterised by an increase in robustness of the femur and shape modifications in the epiphyses. During growth, the neck-shaft angle decreases and the size of the greater and lesser trochanters increase. A significant increase of distal epiphyseal dimensions was recorded, mainly in the medial condyle. The angular remodeling of both the neck and the bicondylar regions of the male femur continues until 16 and 15 years, respectively. Female and male femur each followed divergent growth trajectories. Males showed a greater variability in neck-shaft and bicondylar angles than females.

DISCUSSION

The timing, morphology and growth trajectories provided on the femur during development can be very helpful in anthropological, paleoanthropological and evolution studies.

Sex Differences in Cartilage Topography and Orientation of the Developing Acetabulum: Implications for Hip Preservation Surgery

BACKGROUND

Increased attention is being placed on hip preservation surgery in the early adolescent. An understanding of three-dimensional (3-D) acetabular development as children approach maturity is essential. Changes in acetabular orientation and cartilage topography have not previously been quantified as the adolescent acetabulum completes development.

QUESTIONS/PURPOSES

We used a novel 3-D CT analysis of acetabular development in children and adolescents to determine (1) if there were sex-specific differences in the growth rate or surface area of the acetabular articular cartilage; (2) if there were sex-specific differences in acetabular version or tilt; and (3) whether the amount of version and tilt present correlated with acetabular coverage.

METHODS

We assessed acetabular morphology in 157 patients (314 hips); 71 patients were male and 86 were female. Patient ages ranged from 8 years to 17 years. A 3-D surface reconstruction of each pelvis was created from CT data using MIMICs software. Custom MATLAB software was used to obtain data from the 3-D reconstructions. We calculated articular surface area, acetabular version, and acetabular tilt as well as novel measurements of acetabular morphology, which we termed "coverage angles." These were measured in a radial fashion in all regions of the acetabulum. Data were organized into three age groups: 8 to 10 years old, 10 to 13 years old, and 13 to 17 years old.

RESULTS

Male patients had less acetabular anteversion in all three age groups, including at maturity (7° versus 13°, p<0.001; 10° versus 17°, p<0.001; 14° versus 20°, p<0.001). Males had less acetabular tilt in all three age groups (32° versus 34°, p=0.03; 34° versus 38°, p<0.001; 39° versus 41°, p=0.023). Increases in anteversion correlated with increased posterior coverage angles (r=0.805; p<0.001). Increases in tilt were correlated with increases in superior coverage angles (r=0.797; p<0.001). The posterosuperior regions of the acetabulum were the last to develop and this process occurred earlier in females compared with males. Articular surface area increased from 18 (8-10 years) to 24 cm(2) (13-17 years) in males and from 17 (8-10 years) to 21 cm(2) (13-17 years) in females. [corrected]. Articular surface area was higher in males beginning in the 10- to 13-year-old age group (p=0.001).

CONCLUSIONS

Using a novel technique to analyze acetabular morphology, we found that acetabular development occurs earlier in females than males. The posterosuperior region of the acetabulum is the final region to develop. The articular cartilage surface area and articular cartilage coverage of the femoral head are increasing in addition to total coverage of the femoral head during the final stages of acetabular development.

LEVEL OF EVIDENCE

Level III, prognostic study.

The underused hip in ipsilaterally orthotics-dependent children

BACKGROUND

The aim of this investigation is the development of primarily healthy hips in children who have required orthoses/protheses over the long term due to ipsilateral distally located deformities of the leg. These children show ipsilateral in-toeing gait and Duchenne's limping followed by a coxa valga antetorta and facultative hip decentration. A practical question is whether these hips are in danger of decompensation. An additional theoretical question is how the external shape and internal architecture changes if a primarily healthy hip is underused.

METHODS

Ten children with healthy hips who are unilaterally long-term orthotics/prosthetics-dependent agreed to undergo an instrumental gait analysis. The results were analyzed and correlated with clinical findings, a common activity score and planimetric radiographic data.

RESULTS

The intra-individual comparison revealed a number of significant changes in the hip of the deformed leg (p < 0.05). Clinically, the internal rotation was increased (15° ± 4.2°), while the external rotation was diminished (13° ± 1.3°). Radiologically, the projected caput-collum-diaphyseal angle, the lesser trochanter to articular surface distance and the head-shaft angle were increased by 11.1° ± 15.4°, 5.8 ± 4.2 mm and 11.9° ± 0.6°, respectively. Both the Sharp and acetabular angles were increased, the former by 3.6° ± 0.6° and the latter by 3.2° ± 0.6°. Kinetic gait analysis showed increased stride length (6.8 ± 3.7 cm), shortened stance phase (6.6 ± 1.6 %) and reduced forces transmitted to the ground (92.2 ± 34.3 N). The kinematic analysis showed increased hip abduction (14.0° ± 8.2°), while the pelvic obliquity was not significantly changed (0.01° ± 0.01°).

CONCLUSIONS

Duchenne's limp and lack of weight-bearing stress are the decisive pathogenic factors of the underused coxa valga and acetabular dysplasia. These changes follow the mechanobiological concept of "function modifies design", which means function influences external shape and internal architecture of bones and joints. As a practical consequence we recommend that one pelvic radiograph be performed as a precaution at the end of puberty of children with these conditions.

LEVEL OF EVIDENCE

Level II retrospective study.

The Hyperflexible Hip: Managing Hip Pain in the Dancer and Gymnast

Context:

Dance, gymnastics, figure skating, and competitive cheerleading require a high degree of hip range of motion. Athletes who participate in these sports use their hips in a mechanically complex manner.

Evidence Acquisition:

A search of the entire PubMed database (through December 2013) and additional searches of the reference lists of pertinent articles.

Study Design:

Systematic review.

Level of Evidence:

Level 3.

Results:

Whether innate or acquired, dancers and gymnasts have some hypermobility that allows their hips to be placed in potentially impinging or unstable positions required for their given activity. Such extremes of motion can result in both intra-articular and extra-articular impingement as well as compensatory osseous and muscular pathology. In addition, dancers and gymnasts are susceptible to impingement-induced instability. Dancers with innate generalized hyperlaxity are at increased risk of injury because of their activities and may require longer recovery times to return to play. Both nonoperative and operative treatments (arthroscopic and open) have an important role in returning flexibility athletes to their preoperative levels of sport and dance.

Conclusion:

Because of the extreme hip motion required and the compensatory soft tissue laxity in dancers and gymnasts, these athletes may develop instability, impingement, or combinations of both. This frequently occurs in the setting of subtle pathoanatomy or in patients with normal bony anatomy. With appropriate surgical indications and the correct operative technique, the treating surgeon can anticipate high levels of return to play for the gymnast and dancer with hip pain.

Treatment of hip subluxation in skeletally mature patients with cerebral palsy

Hip subluxation is common in children with spastic cerebral palsy. Most physicians favor intervention to treat hip subluxation in skeletally immature patients with cerebral palsy. However, treatment in skeletally mature patients with cerebral palsy is controversial. The goal of this study was to evaluate radiographic and clinical outcomes after hip reconstruction in skeletally mature patients with cerebral palsy. The authors performed a retrospective review of all skeletally mature patients (n=20) with cerebral palsy who underwent hip surgery for subluxation at the authors' institution between 2005 and 2011. Charts were reviewed for demographic characteristics, procedure, follow-up, and complications. Acetabular index, migration index, and neck-shaft angle were measured on preoperative and most recent radiographs. Average follow-up was 2.2 years. Average migration index for the entire group improved from 57% to 20% (P<.0001). Of patients who had all radiographic abnormalities addressed at surgery (varus derotational femoral osteotomy for neck-shaft angle >135°, open reduction for migration index >50%, and acetabular osteotomy for acetabular index >25°), 91% had a final migration index of less than 25%. In patients who did not have all radiographic abnormalities addressed, 33% had a migration index of less than 25% at final follow-up. No intraoperative complications occurred; however, 13 patients had at least 1 postoperative complication. Hip subluxation in skeletally mature patients with cerebral palsy is difficult to treat and is associated with a high incidence of complications. The likelihood of a successful outcome appears to be related to the appropriateness of the surgical procedure. When all radiographic abnormalities were addressed during surgery, a successful radiographic outcome at final follow-up was much more likely than when intervention was less comprehensive.

Three-dimensional quantitative analysis of the proximal femur and the pelvis in children and adolescents using an upright biplanar slot-scanning X-ray system

BACKGROUND

The anatomy and biomechanics of the pelvis and lower limbs play a key role in the development of orthopaedic disorders.

OBJECTIVE

This study aimed to establish normal reference standards for the measurement of gender-specific pelvic and femoral parameters in children and adolescents with the EOS 2-D/3-D system.

MATERIALS AND METHODS

EOS 2-D images of 508 individuals (ages 4-16 years) were obtained as part of routine diagnostics. Patients with lower limb abnormalities were excluded. Pelvic and femoral surface 3-D models were generated and clinical parameters calculated by sterEOS 3-D reconstruction software. Data were evaluated using Spearman correlation, paired-samples and independent-samples t-test and linear regression analysis.

RESULTS

Changes in anatomical parameters were found to correlate with age and gender in 1) femoral mechanical axis length: 27.3-43.7 cm (males), 25.5-41.2 cm (females), 2) femoral head diameter: 29.4-46.1 mm (males), 27.7-41.3 mm (females), 3) femoral offset: 26.8-42.4 mm (males), 25.5-37.9 mm (females) and 4) femoral neck length: 35.1-52.9 mm (males), 32.8-48.1 mm (females). There was no gender-specific correlation for the neck shaft angle with values from 130.4° to 129.3°, for femoral torsion (22.5°-19.4°), for sacral slope (39.0°-44.4°) and for lateral pelvic tilt (5.1 mm-6.2 mm). Sagittal pelvic tilt exhibited no significant correlation with age showing average values of 6.5°.

CONCLUSIONS

The EOS 2-D/3-D system proved to be a valuable method in the evaluation of female and male developmental changes in pelvic and lower limb anatomical parameters, in normal individuals younger than 16 years of age.

Radiographic changes in nutritional ricket hips in children in response to treatment

PURPOSE

To review radiographic changes in the proximal femurs of children of different ages during the course of treatment for nutritional rickets.

METHODS

Pelvic radiographs of 161 children aged ≤ 13 years with nutritional rickets were retrospectively reviewed. Patients were treated with dietary counselling and vitamin D and calcium supplementation. Patients were followed up at week 3 and thereafter at a 2-month interval until ulnar convexity was achieved. Sequential radiographs of the hips in children of different ages were reviewed for each growth plate in terms of (1) the direction of growth, (2) active areas, (3) contribution of growth, and (4) the structure of the epiphysis. Radiographs were superimposed for comparison by matching the triradiate cartilage and the ischial portion of the obturator foramen.

RESULTS

The direction of growth of the growth plates was from the physeal plate that is the longitudinal growth plate of the neck (LGP), the femoral neck isthmus (FNI), and the trochanteric growth plate (TGP) to the diaphyseal region, and from the perichondrium to the ossification centre in the proximal femoral epiphysis. Before the age of one year, the growth zone of the proximal femur was homogenous, with no differentiation between the LGP, FNI, and TGP. By the age of 2 years, the differentiation was more clearly established; the FNI was usually smaller than the TGP and LGP. By the age of 3 years, the FNI became prominent and the TGP remained small. By the age of 4 years, the ossification centre of the greater trochanter appeared, and the LGP extended medially as a medial overhang (MOH). During the children's growth, the LGP, FNI, or TGP remained active to a variable extent and were distinct until the age of 6 years. Gradually, the periphery of the LGP became less active than the centre of the LGP and gave rise to the 'eye sign'. The MOH generally ceased to be active beyond the age 9 years. By the age of 12 years, the TGP and FNI were minimally active and only the centre of the LGP remained active.

CONCLUSION

The mineralisation process of healing rickets provides a useful biological marker for patterns of growth. Knowledge of the quantitative contribution of various growth plates of the proximal femur in childhood may increase the understanding of the pathomechanism of hip deformations.

Reliability of radiologic measures of hip displacement in a cohort of preschool-aged children with cerebral palsy

BACKGROUND

Radiologic hip surveillance is recommended for children with cerebral palsy (CP) at risk of hip displacement. Young children with abnormal proximal femoral geometry (Hilgenreiner epiphyseal angle, HEA) may be more likely to develop hip displacement, less likely to respond to nonsurgical intervention, and may benefit from earlier surgical referral. The reliability of radiographic measures of migration percentage (MP) in the immature pelvis of young children has been reported in smaller retrospective studies; HEA has not been examined in this population. This prospective study describes the reliability of MP and HEA in very young children with CP.

METHODS

Participants were entered from tertiary referral center CP clinics into a prospectively recruited population-based cohort for hip surveillance with pelvic radiography using standardized patient position, at 18, 24, 30, 36, and 48 months. All Gross Motor Function Classification System (GMFCS) levels were included. Two independent raters assessed radiographs for HEA and MP. The intraclass correlation coefficient (ICC) was computed as a measure of interrater and intrarater reliability. The correlation coefficient between HEA and femoral position was computed.

RESULTS

Ninety-eight children less than 25 months (spasticity=83, 85%; GMFCS IV-V=38, 39%), and 114 children 25 to 48 months (spasticity=96, 85%; GMFCS IV-V=37, 32%) were included from 133 unique participants (spasticity=111, 84%; GMFCS IV-V=42, 32%). Of these 79 children were studied in both age groups. Overall interrater and intrarater reliability of MP was high [ICC=0.93; 95% confidence interval (CI), 0.91-0.95]; SEM was 3.9% (single) and 5.5% (sequential). Perfect concordance for classification of marked hip displacement (MP>30%) occurred in 217 cases (95.2%); nonweighted κ=0.80; 95% CI, 0.68-0.91. For HEA, overall reliability was high (ICC=0.89; 95% CI, 0.85-0.93); SEM=4.8% (single) and 6.7% (sequential). Correlation between changes in HEA and femoral abduction was poor (coefficient=-0.27, P=0.244).

CONCLUSIONS

MP and HEA can be reliably applied to very young children with CP, with high reliability for both measures. Measured HEA values appear to be independent of patient position, and may reflect genuine changes in proximal femoral geometry. A longitudinal study should be performed to determine the relationship between HEA and later hip outcomes.

LEVEL OF EVIDENCE

Level I/II--testing and development of diagnostic tests.

Ontogeny of the female femur: geometric morphometric analysis applied on current living individuals of a Spanish population

In this study we describe the development of the female femur based on the analysis of high-resolution radiographic images by means of geometric morphometrics, while assessing the usefulness of this method in these kinds of studies. The material analysed consisted of digital images in DICOM format (telemetries), corresponding to 184 left femora in anterior view, obtained from the database of the Hospital Sant Joan de Déu of Barcelona (Spain). Bones analysed corresponded to individuals from 9 to 14 years old. Size and shape variation of the entire femur was quantified by 22 two-dimensional landmarks. Landmark digitisation errors were assessed using Procrustes anova test. Centroid size (CS) variation with age was evaluated by an anova test. Shape variation was assessed by principal component analysis. A mancova test between the first five principal components and age, using the CS as covariable, was applied. Results indicated that both size and shape vary significantly with age. Several age-related shape changes remained significant after removing the allometric effect. In general, an increase in the robustness of the bone and noticeable phenotypic changes in certain areas of the femur were observed. During growth in the proximal region of the femur, the collo-diaphyseal angle decreases, the neck of the femur widens and the fovea moves to a lower position, standing more in line with the plane of the neck. Likewise, the size of the greater and lesser trochanters increase. In the distal region, a significant increase of epiphyseal dimensions was recorded, mainly in the medial condyle. The angular remodelling of the neck and the bicondylar region of the femur in females continues until 13 years old. The information provided in the present study increases our knowledge on the timing and morphology of the femur during development, and in particular the morphology of the different femoral ossification centres during development.

Australian Cerebral Palsy Child Study: protocol of a prospective population based study of motor and brain development of preschool aged children with cerebral palsy

BACKGROUND

Cerebral palsy (CP) results from a static brain lesion during pregnancy or early life and remains the most common cause of physical disability in children (1 in 500). While the brain lesion is static, the physical manifestations and medical issues may progress resulting in altered motor patterns. To date, there are no prospective longitudinal studies of CP that follow a birth cohort to track early gross and fine motor development and use Magnetic Resonance Imaging (MRI) to determine the anatomical pattern and likely timing of the brain lesion. Existing studies do not consider treatment costs and outcomes. This study aims to determine the pathway(s) to motor outcome from diagnosis at 18 months corrected age (c.a.) to outcome at 5 years in relation to the nature of the brain lesion (using structural MRI).

METHODS

This prospective cohort study aims to recruit a total of 240 children diagnosed with CP born in Victoria (birth years 2004 and 2005) and Queensland (birth years 2006-2009). Children can enter the study at any time between 18 months to 5 years of age and will be assessed at 18, 24, 30, 36, 48 and 60 months c.a. Outcomes include gross motor function (GMFM-66 & GMFM-88), Gross Motor Function Classification System (GMFCS); musculoskeletal development (hip displacement, spasticity, muscle contracture), upper limb function (Manual Ability Classification System), communication difficulties using Communication and Symbolic Behaviour Scales-Developmental Profile (CSBS-DP), participation using the Paediatric Evaluation of Disability Inventory (PEDI), parent reported quality of life and classification of medical and allied health resource use and determination of the aetiology of CP using clinical evaluation combined with MRI. The relationship between the pathways to motor outcome and the nature of the brain lesion will be analysed using multiple methods including non-linear modelling, multilevel mixed-effects models and generalised estimating equations.

DISCUSSION

This protocol describes a large population-based study of early motor development and brain structure in a representative sample of preschool aged children with CP, using direct clinical assessment. The results of this study will be published in peer reviewed journals and presented at relevant international conferences.

TRIAL REGISTRATION

Australia and New Zealand Clinical Trials Register (ACTRN1261200169820).

Midterm results after subtrochanteric end-to-side valgization osteotomy in severe infantile coxa vara

BACKGROUND

For the treatment of the severe infantile coxa vara it is mandatory for the orthopaedic surgeon to observe the mechanobiology of the growing hip before and after the surgical intervention. We hereby would like to present our experiences with the subtrochanteric end-to-side valgization osteotomy and to compare the procedure with the alternatively used Y-shaped osteotomy as described by Pauwels.

METHODS

Thirteen patients (20 hips) who had undergone subtrochanteric end-to-side valgization were followed for a mean 6.2 years (range, 0.8 to 12.8 y). At the time of surgery the mean age was 7.1 years (range, 2.0 to 13.3 y), last follow-up examination was performed at a mean of 13.4 years of age (range, 5.1 to 18.3 y). The deformities were etiologically based on 5 entities: congenital coxa vara (n=1), osteochondrodysplasias (n=12), postosteomyelitic coxa vara (n=5), and avascular femoral head necrosis in the course of congenital dysplasia of the hip (n=2). The follow-up rate was 100%.In addition, we analyzed a total of 93 pelvic radiographies with a total of 139 hip joints. Thirty angles and distances were assessed according to parameters described in the literature.

RESULTS

Although preoperatively 12 patients presented with a positive Trendelenburg's sign, it was only present postoperatively in 2 patients. Duchenne's limp reduced from 10 to 1. All of the 15 preoperatively apparent nonunions could be healed by means of surgery. Two hips redeveloped pathologically lowered collodiaphyseal angles postoperatively, one of which had to undergo revision surgery. Preoperatively 15 out of 20 patients (75%) showed nonunions all of which healed after surgery. No recurrence could be seen at the time of the last follow-up.The following angles were assessed on plain radiographies of the pelvis preoperatively and directly postoperatively as well as on the last follow-up at a mean of 85 months: CCD-angle 98 degrees/156 degrees/144 degrees, EY-angle 55 degrees/5 degrees/15.7 degrees, AY-angle 32 degrees/75 degrees/66 degrees, CE-angle 20 degrees/25 degrees/18 degrees, AC-angle 20 degrees/18 degrees/20 degrees. The articulotrochanteric distance was 5 mm/26 mm/14 mm.

CONCLUSIONS

The subtrochanteric end-to-side valgization osteotomy showed to be highly effective in the management of the infantile coxa vara, improving the clinical impairment of the patients postoperatively. All of the preoperatively present nonunions showed osseous consolidation at follow-up examination. Only minor revarization tendencies could be found. The procedure is technically less demanding, safer and more efficient regarding the lengthening of the affected limb in comparison to the Y-shaped intertrochanteric osteotomy as described by Pauwels.

LEVEL OF EVIDENCE

Case-control study (EBM-level III).

Evaluation of experienced surgeons' decisions regarding the need for secondary surgery in developmental dysplasia of the hip

BACKGROUND

We aimed to evaluate experienced surgeons' decisions regarding the need for secondary surgery in developmental dysplasia of the hip (DDH) at 5 to 7 years of age.

METHODS

We selected 21 hips from 17 patients who had mid-term and skeletally mature radiographs and who had neither had complications nor secondary surgery until skeletal maturity after having an initial soft tissue surgery for DDH before the age of 18 months. Twenty experienced orthopaedic surgeons evaluated the mid-term follow-up radiographs of these hips in terms of their need for secondary surgery.

RESULTS

On the basis of management grading of the observers at mid-term follow-up, the risk of unnecessary surgical management was 12% in hips that would eventually be normal at skeletal maturity. The risk of not performing needed surgery was 40% in hips that would eventually become dysplastic at skeletal maturity. Experience of the surgeons in terms of years had no significant effect on the management decisions. The center-edge angle, the acetabular index angle (AIA), percentage of femoral head coverage, Shenton line, and the acetabular angle of Sharp were the 5 most commonly used radiographic parameters at mid-term follow-up to assess whether a secondary surgery would be needed. Center-edge angle, AIA, femoral head coverage, and Shenton line correlated, whereas the acetabular angle did not significantly correlate with surgeons' quantitative management decisions on the basis of mid-term radiographs.

CONCLUSIONS

Experienced surgeons are more likely to opt for nonoperative management in hips that show no ischemic changes or instability at 5 to 7 years of age even in the presence of slightly abnormal radiographic measurements. AIA is considered the best radiographic parameter for making decisions regarding the need for secondary surgery in DDH at 5 to 7 years of age.

LEVEL OF EVIDENCE

Level II prognostic study.

Utility of combined hip abduction angle for hip surveillance in children with cerebral palsy

BACKGROUND

Spontaneous hip lateralization complicates the management of non-ambulatory children with cerebral palsy (CP). It can be diagnosed early using radiographs, but it involves standardization of positioning and exposure to radiation. Hence, the aim of this study was to assess the utility of Combined hip abduction angle (CHAA) in the clinical setting to identify those children with CP who were at greater risk to develop spontaneous progressive hip lateralization.

MATERIALS AND METHODS

One hundred and three children (206 hips) with CP formed our study population. There were 48 boys and 55 girls aged 2-11 years (mean 5.03 years). 61 children were Gross Motor Function Classification System (GMFCS) level 5, while 42 were GMFCS level 4. Clinical measurements of CHAA were statistically correlated with radiographic measurements of Reimer's migration percentage (MP) for bivariate associations using χ(2) and t tests.

RESULTS

CHAA is evaluated against MP which is considered as a reliable measure of hip subluxation. Thus, for CHAA, sensitivity was 74.07% and specificity was 67.35%. False-positive rate was 32.65% and false-negative rate was 25.93%.

CONCLUSIONS

Our study shows that correlation exists between CHAA and MP, which has been proved to be useful for hip screening in CP children at risk of hip dislocation. CHAA is an easy, rapid, cost-effective clinical test which can be performed by paraclinical health practitioners (physiotherapists) and orthopedic surgeons.

Gillette Gait Index in adults

Gillette Gait Index (GGI) is a very useful tool to assess gait abnormalities. However, it seems that it has only been validated in children with cerebral palsy. Nevertheless, the parameters used to compute GGI are not specific to children population. Our aim is to demonstrate that GGI could also be used to evaluate adults gait abnormalities. 44 adults (25 healthy and 19 pathological) participated to this study. Pathological subjects had a diagnosis of central nervous system pathology (6 with spinal cord injury and 13 with brain injury). We first, compared the kinematic parameter values of our healthy adult group to healthy children group in previous studies. It appears that those parameters' variability is a bit lower in adults, which makes the GGI more sensitive. Moreover, the GGI in adults is too much dependent on one parameter among the 16 proposed by Schutte et al. (2000), the "Time of Peak Flexion". Finally, the Edinburgh Visual Gait Score (EVGS) is correlated to GGI in children. To emphasize the relevance of GGI in adults, we have evaluated the correlation between EVGS and GGI in our pathological group. Those two parameters are indeed highly correlated. All these results allow us to conclude that the GGI computed with the 15 remaining parameters is a useful tool to assess gait abnormalities in adults.

Angle estimation of human femora in a three-dimensional virtual environment

The estimation of human femur morphology and angulation provide useful information for assisted surgery, follow-up evaluation and prosthesis design, cerebral palsy management, congenital dislocation of the hip and fractures of the femur. Conventional methods that estimate femoral neck anteversion employ planar projections because accurate 3D estimations require complex reconstruction routines. In a recent work, we proposed a cylinder fitting method to estimate bifurcation angles in coronary arteries and we thought to test it in the estimation of femoral neck anteversion, valgus and shaft-neck angles. Femora from 10 patients were scanned using multisliced computed tomography. Virtual cylinders were fitted to 3 regions of the bone painted by the user to automatically estimate the femoral angles. Comparisons were made with a conventional manual method. Inter- and intra-reading measurements were evaluated for each method. We found femoral angles from both methods strongly correlated. Average anteversion, neck-shaft and valgus angles were 17.5°, 139.5°, 99.1°, respectively. The repeatability and reproducibility of the automated method showed a 5-fold reduction in inter- and intra-reading variability. Accordingly, the coefficients of variation for the manual method were below 25% whereas for the automated method were below 6%. The valgus angle assessment was globally the most accurate with differences below 1°. Maximum distances from true surface bone points and fitting cylinders attained 6 mm. The employment of virtual cylinders fitted to different regions of human femora consistently helped to assess true 3D angulations.