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Background: Cam morphology develops during skeletal growth, but its influence on cartilage and the labrum in high-impact athletes later in life is unknown., Purpose: To (1) explore the association between the presence and duration of cam morphology during adolescence and the cartilage and labral status 7 to 12 years later and (2) report the prevalence of cartilage loss and labral damage in a population of young male athletes (<32 years old) who played professional soccer during skeletal growth., Study Design: Cohort study (Prognosis); Level of evidence, 2., Methods: A total of 89 healthy male academy soccer players from the Dutch soccer club Feyenoord (aged 12-19 years) were included at baseline. At baseline and 2.5- and 5-year follow-ups, standardized supine anteroposterior pelvis and frog-leg lateral radiographs of each hip were obtained. At 12-year follow-up, magnetic resonance imaging of both hips was performed. Cam morphology was defined by a validated alpha angle ≥60° on radiographs at baseline or 2.5- or 5-year follow-up when the growth plates were closed. Hips with the presence of cam morphology at baseline or at 2.5-year follow-up were classified as having a "longer duration" of cam morphology. Hips with cam morphology only present since 5-year follow-up were classified as having a "shorter duration" of cam morphology. At 12-year follow-up, cartilage loss and labral abnormalities were assessed semiquantitatively. Associations were estimated using logistic regression, adjusted for age and body mass index., Results: Overall, 35 patients (70 hips) with a mean age of 28.0 ± 2.0 years and mean body mass index of 24.1 ± 1.8 participated at 12-year follow-up. Cam morphology was present in 56 of 70 hips (80%). The prevalence of cartilage loss was 52% in hips with cam morphology and 21% in hips without cam morphology (adjusted odds ratio, 4.52 [95% CI, 1.16-17.61]; P = .03). A labral abnormality was present in 77% of hips with cam morphology and in 64% of hips without cam morphology (adjusted odds ratio, 1.99 [95% CI, 0.59-6.73]; P = .27). The duration of cam morphology did not influence these associations., Conclusion: The development of cam morphology during skeletal growth was associated with future magnetic resonance imaging findings consistent with cartilage loss in young adults but not with labral abnormalities., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: The Anna Foundation (Anna Fonds) and the Dutch Orthopaedic Research and Education Foundation provided financial support for this study. D.E. has received a personal educational grant (€2200) from Zimmer Biomet. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Cam morphology describes an asphericity of the femoral head that develops during adolescence, is highly prevalent in athletes, and predisposes individuals to future osteoarthritis. However, it's aetiology remains poorly understood. The aim of this study was to perform 3-year longitudinal follow-up of a control population and football club academy cohort to compare the change in hip and growth plate anatomy between athletes and controls. MRI and questionnaires were used to characterise change in hip and growth plate anatomy and quantify activity levels. 121 male academy footballers and 107 male and female controls participated at baseline. Footballers experienced significantly greater increases in femoral head asphericity (4.83 degrees (95% CI: 2.84 to 6.82), p < 0.001) than controls. A positive correlation existed between activity levels and change in femoral head morphology (coefficient 0.79, p  ≤  0.001). Greatest morphological change occurred in individuals aged 11-12 years at baseline, with no significant change in individuals aged 14 years and older at baseline. Cam morphology development was secondary to soft tissue hypertrophy and lateral growth plate extension. In conclusion, excessive loading of the hip joint through exercise prior to 14 years of age may result in growth plate adaptations causing cam morphology. Potential interventions may include training type and load modification in young adolescent football players., (© 2021. The Author(s).)

Introduction: Adolescent total hip arthroplasty (THA) is guarded partially due unclarity as to when pediatric hip joints reach full development. This study sought to identify when maximum acetabular and femoral head diameters are achieved with relation to chronological and skeletal age., Materials and Methods: Consecutive femoral head and acetabular diameters were measured in a random sample of 54 female and 78 male subjects, which were queried from a historical collection of annual radiographs of children. Femoral head and triradiate physeal plates were scored according to Oxford bone parameters., Results: At 14 years females had femoral diameters of 4.16 +/- 0.23 cm and acetabular diameters of 5.15 +/- 0.30 cm. At 16 years males had femoral diameters of 4.85 +/- 0.30 cm and acetabular diameters of 5.90 +/- 0.35 cm. In the year following maximal femoral Oxford scores, no significant change was seen in femur and acetabulum diameters in females and in femur diameters in males. In the year following maximal acetabular Oxford scores, there was a significant increase in both femur and acetabulum diameters in both females and males., Conclusions: Females on average reach maximum pelvis maturity at 14 years and males reach maximum pelvis maturity at 16 years. A closed femoral head was found to be a good marker of full hip growth, while a closed triradiate was not. This study provides anatomical data for surgeons to consider in assessing risk factors of THA failure in adolescents., (© 2020 American Association of Clinical Anatomists.)

Background: Cam morphologies seem to develop with an increased prevalence in adolescent boys performing high-impact sports. The crucial question is at what age the cam morphology actually develops and whether there is an association with an aberration of the shape of the growth plate at the cam morphology site., Questions/purposes: (1) What is the frequency of cam morphologies in adolescent ice hockey players, and when do they appear? (2) Is there an association between an extension of the physeal growth plate and the development of a cam morphology? (3) How often do these players demonstrate clinical findings like pain and lack of internal rotation?, Methods: A prospective, longitudinal MRI study was done to monitor the proximal femoral development and to define the appearance of cam morphologies in adolescent ice hockey players during the final growth spurt. Young ice hockey players from the local boys' league up to the age of 13 years (mean age 12 ± 0.5 years) were invited to participate. From 35 players performing on the highest national level, 25 boys and their parents consented to participate. None of these 25 players had to be excluded for known disease or previous surgery or hip trauma. At baseline examination as well as 1.5 and 3 years later, we performed a prospective noncontrast MRI scan and a clinical examination. The three-dimensional morphology of the proximal femur was assessed by one of the authors using radial images of the hip in a clockwise manner. The two validated parameters were: (1) the alpha angle for head asphericity (abnormal > 60°) and (2) the epiphyseal extension for detecting an abnormality in the shape of the capital physis and a potential correlation at the site of the cam morphology. The clinical examination was performed by one of the authors evaluating (1) internal rotation in 90° of hip and knee flexion and (2) hip pain during the anterior impingement test., Results: Cam morphologies were most apparent at the 1.5-year follow-up interval (10 of 25; baseline versus 1.5-year follow-up: p = 0.007) and a few more occurred between 1.5 and 3 years (12 of 23; 1.5-year versus 3-year follow-up: p = 0.14). At 3-year follow-up, there was a positive correlation between increased epiphyseal extension and a high alpha angle at the anterosuperior quadrant (1 o'clock to 3 o'clock) (Spearman correlation coefficient = 0.341; p < 0.003). The prevalence of pain on the impingement test and/or restricted internal rotation less than 20° increased most between 1.5-year (1 of 25) and the 3-year follow-up (6 of 22; 1.5-year versus 3-year follow-up: p = 0.02)., Conclusion: Our data suggest that a cam morphology develops early during the final growth spurt of the femoral head in adolescent ice hockey players predominantly between 13 to 16 years of age. A correlation between an increased extension of the growth plate and an increased alpha angle at the site of the cam morphology suggests a potential underlying growth disturbance. This should be further followed by high-resolution or biochemical MRI methods. Considering the high number of cam morphologies that correlated with abnormal clinical findings, we propose that adolescents performing high-impact sports should be screened for signs of cam impingement, such as by asking about hip pain and/or examining the patient for limited internal hip rotation., Level of Evidence: Level I, prognostic study., Competing Interests: All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2021 by the Association of Bone and Joint Surgeons.)

Background: Developmental dysplasia of the hip (DDH) is the most common joint disease in child orthopedics. Secreted Frizzled-Related Protein 3 (FRZB) plays an important role in joint development. however, no direct association between FRZB and DDH has been demonstrated., Methods: Analysis of genotype distribution and allele frequency for detected single nucleotide polymorphisms (SNP) of FRZB was performed. FRZB expression was assayed in DDH joint tissues. Further experiments to identify the chondrogenic properties of FRZB were conducted. Potential upstream miRNAs for FRZB were assayed in DDH., Results: Significant difference in genotype distribution for rs3768842 (OR=1.46, P=0.0081) and rs2242040 (OR=0.65, P=0.0067) was found. DDH joint tissues showed significantly higher FRZB expression. FRZB demonstrated chondrogenic and anti-hypertrophic properties in vitro . FRZB modulated cell adhesion pathway and cell spreading by regulating integrins expressions. Upstream miRNAs regulating FRZB expression were identified in DDH synovial fluid. Experiments indicated that downregulated miRNA-454 caused FRZB upregulation in DDH joint., Conclusion: Dysregulated FRZB and its loci were associated with DDH. As a Wnt antagonist with chondrogenic properties, FRZB modulated cell adhesion pathway and cell spreading by regulating integrins expressions. FRZB in multiple DDH joint tissues might be mediated by the dysregulated miRNA expression profiles in the joint synovial fluid.

Context: Among patients with type 1 diabetes (T1D), the risk of hip fracture is up to 6-fold greater than that of the general population. However, the cause of this skeletal fragility remains poorly understood., Objective: To assess differences in hip geometry and imaging-based estimates of bone strength between youth with and without T1D using dual-energy x-ray absorptiometry (DXA)-based hip structural analysis., Design: Cross-sectional comparison., Participants: Girls ages 10 to 16 years, including n = 62 with T1D and n = 61 controls., Results: The groups had similar age, bone age, pubertal stage, height, lean mass, and physical activity. Bone mineral density at the femoral neck and total hip did not differ in univariate comparisons but was lower at the femoral neck in T1D after adjusting for bone age, height, and lean mass. Subjects with T1D had significantly lower cross-sectional area, cross-sectional moment of inertia, section modulus, and cortical thickness at the narrow neck, with deficits of 5.7% to 10.3%. Cross-sectional area was also lower at the intertrochanteric region in girls with T1D. Among those T1D subjects with HbA1c greater than the cohort median of 8.5%, deficits in hip geometry and strength estimates were more pronounced., Conclusions: DXA-based hip structural analysis revealed that girls with T1D have unfavorable geometry and lower estimates of bone strength at the hip, which may contribute to skeletal fragility and excess hip fracture risk in adulthood. Higher average glycemia may exacerbate effects of T1D on hip geometry., (• The Author(s) 2020. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The epiphyseal tubercle plays an important role in epiphyseal stabilization. While the majority of studies have focused on tubercle morphology, there is a paucity of information on the morphological features of the metaphyseal fossa, where the tubercle sits on the metaphysis. The goal of this study was to determine the developmental changes in the capital femoral metaphyseal fossa. Computed tomography of the pelvis from 80 children and adolescents 8-15 years old were used to create three-dimensional models of the proximal femur. Depth, width, length, and surface area of the metaphyseal fossa were measured and the impact of age and sex on fossa morphology was assessed using the linear regression and two-way analysis of variance, respectively. The metaphyseal fossa was located in the posterosuperior quadrant of the metaphysis without any variations in the location with increasing age (P > .1). However, with increasing age, there was a reduction in all metaphyseal fossa measurements including the depth, length, width, and surface area (P < .01). No significant differences were noted for the metaphyseal fossa measurements between males and females (P > .1). The metaphyseal fossa reduces in size from 8 to 15 years of age in a similar fashion in males and females. As the metaphyseal fossa adjacent to the tubercle matches the area where a focal radiolucency has been observed in early slipped capital femoral epiphysis (SCFE), further studies should clarify the mechanisms by which the interlocking interaction of the epiphyseal tubercle and its fossa contributes to or is affected by SCFE., (© 2020 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Importance: Peak bone strength, which occurs in early adulthood, is an important marker of the future risk of osteoporosis. It is therefore important to identify modifiable early life factors that are associated with the attainment of peak hip strength., Objective: To investigate the association of time spent in moderate to vigorous-intensity and light-intensity physical activity throughout adolescence with peak hip strength in adulthood., Design, Setting, and Participants: The Avon Longitudinal Study of Parents and Children is a prospective birth cohort study that initially recruited all pregnant women residing within the catchment area of 3 health authorities in southwest England who had an expected delivery date between April 1, 1991, and December 31, 1992. In total, 15 454 eligible pregnant women were enrolled, and 15 589 infants were delivered. Of those, 14 901 infants were alive at age 1 year. The present analysis examined 2569 healthy offspring who had valid physical activity measurements obtained during a clinical assessment for at least 1 age (12, 14, 16, and/or 25 years), with up to 4 repeated accelerometer assessments performed (1 per age-associated clinical visit). Data were analyzed from June 2019 to June 2020., Exposures: Trajectories of accelerometer-assessed time spent in moderate to vigorous-intensity and light-intensity physical activity at ages 12, 14, 16, and 25 years (measured in minutes per day) were identified using latent trajectory modeling. Moderate to vigorous-intensity and light-intensity physical activity were determined using established thresholds of acceleration counts per minute., Main Outcomes and Measures: Femur neck bone mineral density (BMD; measured in g/cm2) at age 25 years assessed by dual-energy radiography absorptiometry scans of the hip., Results: A total of 2569 participants (1588 female participants [62%]) were included in the analysis. Male participants spent more time in moderate to vigorous-intensity activity at each age and had greater adult femur neck BMD than female participants. For each sex, 3 moderate to vigorous-intensity trajectory subgroups and 3 light-intensity trajectory subgroups were identified. With regard to the moderate to vigorous-intensity trajectories, most male participants (85%) were in the low adolescent subgroup, with only 6% and 9% in the high early-adolescent and high mid-adolescent subgroups, respectively. Moderate to vigorous-intensity trajectories in female participants were divided into low adolescent-low adult (73%), low adolescent-high adult (8%), and high adolescent (19%) subgroups. Light-intensity physical activity trajectories were classified into low nonlinear, moderate decreasing, and high decreasing subgroups for both sexes. Femur neck BMD in male participants was greater in the high early-adolescent subgroup (0.38 g/cm2; 95% CI, 0.11-0.66 g/cm2) and the high mid-adolescent subgroup (0.33 g/cm2; 95% CI, 0.07-0.60 g/cm2) compared with the low adolescent (reference) subgroup. Femur neck BMD in female participants was greater in the high adolescent subgroup (0.28 g/cm2; 95% CI, 0.15-0.41 g/cm2) but not in the low adolescent-high adult subgroup (-0.12 g/cm2; 95% CI, -0.44 to 0.20 g/cm2) compared with the low adolescent-low adult (reference) subgroup. A sensitivity analysis using a negative-outcome control variable to explore unmeasured confounding supported these findings. The light-intensity trajectories were not associated with femur neck BMD; for example, differences in femur neck BMD between the high decreasing and low nonlinear subgroups were 0.16 g/cm2 (95% CI, -0.08 to 0.40 g/cm2) in male participants and 0.20 g/cm2 (95% CI, -0.05 to 0.44 g/cm2) in female participants., Conclusions and Relevance: Supporting high-intensity physical activity throughout early life may help to maximize peak hip strength and prevent osteoporosis in later life. Replication of our findings in independent studies will be important.

Objectives: The aims of the present study were to monitor, by radiographic examination, the skeletal development of the pelvis and the femorotibial joints of the domestic cat from the first week of life until the closing of the growth plates., Methods: Radiographic examinations were collected from 15 domestic cats at weekly intervals during the first month and every 2 weeks from the second to the fourth month of age. After that, examinations were performed monthly until the age of 18 months., Results: The ischiopubic growth plate closed at 2 months of age, followed by the fusion of the iliopubic, ilioischial, proximal femoral, greater trochanter and proximal fibular growth plates. The distal femur and proximal tibial growth plates were the last to close, with fusion occurring at 18 months. The mean time to closure of the iliopubic, ilioischial and distal femoral growth plates was shorter in females. The ossification centers first appeared, in ascending order, beginning with the lesser trochanter, followed by the greater trochanter, proximal fibular epiphysis, tibial tuberosity, patella, ischial tuberosity and lateral sesamoid of the popliteus muscle., Conclusions and Relevance: The complete closure of the growth plates of domestic cats occurs at approximately 18 months of age. Skeletal maturation at approximately 18 months of age is an important parameter to be considered in radiographic evaluation of certain skeletal changes, evolution of fractures and nutritional imbalance.

Currently, hip sonography is used for early diagnosis and for monitoring developmental dysplasia of the hip (DDH) treatment in many countries. An early pioneer of ultrasonography for early diagnosis of DDH was Graf. Based on the Graf approach, hip ultrasonography is more sensitive and specific than radiography for the diagnosis of DDH, because of its capability to show cartilaginous structures of the hip joint. The aim of this study was to compare radiographic and ultrasonographic findings in patients treated for DDH. This study included 88 infants (98hips) treated for DDH. Radiography was simultaneously used for treatment and follow-up evaluation in addition to ultrasonography after six months of age. A retrospective evaluation was made of the ultrasonographs and radiographs of these infants. Of the total 98 hips, 28 were normal both ultrasonographically and radiographically, and a pathologic hip was demonstrated in 32 hips both sonographically and radiographically. Hip ultrasonography showed abnormal development in 32 hips, while radiography showed abnormal development in 70 hips. In 38 hips, the findings were normal according to ultrasonography but pathological according to radiography. There were no hips that were normal radiographically but pathological sonographically. When radiography is accepted as the standard imaging method in our study patients, the sensitivity and specificity of hip ultrasonography were determined as 45.7% [95% confidence interval (CI): 41.5-45.7] and 100% (95% CI: 89.4-100), respectively. These findings suggest that hip maturation apparent on ultrasonography may not be consistent with radiographic hip development in infants treated for DDH.

Background: Acetabular version influences joint mechanics and the risk of impingement. Cross-sectional studies have reported an increase in acetabular version during adolescence; however, to our knowledge no longitudinal study has assessed version or how the change in version occurs. Knowing this would be important because characterizing the normal developmental process of the acetabulum would allow for easier recognition of a morphologic abnormality., Questions/purposes: To determine (1) how acetabular version changes during adolescence, (2) calculate how acetabular coverage of the femoral head changed during this period, and (3) to identify whether demographic factors or hip ROM are associated with acetabular development., Methods: This retrospective analysis of data from a longitudinal study included 17 volunteers (34 hips) with a mean (± SD) age of 11 ± 2 years; seven were male and 10 were female. The participants underwent a clinical examination of BMI and ROM and MRIs of both hips at recruitment and at follow-up (6 ± 2 years). MR images were assessed to determine maturation of the triradiate cartilage complex, acetabular version, and degree of the anterior, posterior, and superior acetabular sector angles (reflecting degree of femoral head coverage provided by the acetabulum anteriorly, posteriorly and superiorly respectively). An orthopaedic fellow (GG) and a senior orthopaedic resident (PJ) performed all readings in consensus; 20 scans were re-analyzed for intraobserver reliability. Thereafter, a musculoskeletal radiologist (KR) repeated measurements in 10 scans to test interobserver reliability. The intra- and interobserver interclass correlation coefficients for absolute agreement were 0.85 (95% CI 0.76 to 0.91; p < 0.001) and 0.77 (95% CI 0.70 to 0.84), respectively. All volunteers underwent a clinical examination by a senior orthopaedic resident (PJ) to assess their range of internal rotation (in 90° of flexion) in the supine and prone positions using a goniometer. We tested investigated whether the change in anteversion and sector angles differed between genders and whether the changes were correlated with BMI or ROM using Pearson's coefficient. The triradiate cartilage complex was open (Grade I) at baseline and closed (Grade III) at follow-up in all hips., Results: The acetabular anteversion increased, moving caudally further away from the roof at both timepoints. The mean (range) anteversion angle increased from 7° ± 4° (0 to 18) at baseline to 12° ± 4° (5 to 22) at the follow-up examination (p < 0.001). The mean (range) anterior sector angle decreased from 72° ± 8° (57 to 87) at baseline to 65° ± 8° (50 to 81) at the final follow-up (p = 0.002). The mean (range) posterior (98° ± 5° [86 to 111] versus 97° ± 5° [89 to 109]; p = 0.8) and superior (121° ± 4° [114 to 129] to 124° ± 5° [111 to 134]; p = 0.07) sector angles remained unchanged. The change in the anterior sector angle correlated with the change in version (rho = 0.5; p = 0.02). The change in version was not associated with any of the tested patient factors (BMI, ROM)., Conclusions: With skeletal maturity, acetabular version increases, especially rostrally. This increase is associated with, and is likely a result of, a reduced anterior acetabular sector angle (that is, less coverage anteriorly, while the degree of coverage posteriorly remained the same). Thus, in patients were the normal developmental process is disturbed, a rim-trim might be an appropriate surgical solution, since the degree of posterior coverage is sufficient and no reorientation osteotomy would be necessary. However, further study on patients with retroversion (of various degrees) is necessary to characterize these observations further. The changes in version were not associated with any of the tested patient factors; however, further study with greater power is needed., Level of Evidence: Level II, prognostic study.

The basic law of mechanobiology states that the external form and internal architecture of the skeleton and joints follow the functional stimuli that act upon them. Radiographs and magnetic resonance imaging reflect the loading history of the growing child, enabling an experienced radiologist to analyze the clinical functioning of patients by interpreting imaging studies. Concerning the hip joint, the physes of the coxal femoral end, the coxal femoral epiphysis with its epiphyseal growth plate, as well as the apophysis of the greater trochanter with its trochanteric growth plate, are the essential organ structures subject to internal forces. They determine the definitive geometric shape of the proximal femur. Indirectly they influence the appearance of the acetabulum and the centration of the hip joint., Competing Interests: None declared., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Introduction: Developmental dysplasia of the hip (DDH) is a major cause of disability in children, and the genetic mechanism of this disease remains unclear. In our previous study, we found that pregnancy-associated plasma protein-A2 (PAPP-A2) was associated with DDH significantly., Objectives: The aim of this study was to investigate the insulin-like growth factor (IGF) expression and collagen synthesis as well as cartilage proliferation-related proteins in the case of abnormal expression of Pappa2 in mice to research the relationship between PAPP-A2 and the pathological changes of DDH., Methods: In vivo animal experiments, the mice were directly injected with 50 µl of Cas9/PAPP-A2 sgRNA lentiviruses around the hip to downregulate the Pappa2 gene expression and injected with control lentiviruses on the other side, then to observe the expression and localization of related proteins. And in an in vitro experiment, mice fibroblasts and primary chondrocytes were cultured with insulin-like growth factor binding protein-5 (IGFBP-5) protein, PAPP-A2 protein and Cas9/PAPP-A2 sgRNA lentiviruses to detect of related proteins and mRNA expression., Results: Cartilage proliferation-related proteins demonstrated a significant decrease in the PAPP-A2 knockdown hips acetabulum and femoral head cartilage, meanwhile the IGF expression was also downregulated in the soft tissue around the acetabulum compared with the control hips. Furthermore, the role PAPP-A2 played in chondrocytes and fibroblasts was the same as in the in vivo experiments, downregulation of PAPP-A2 expression or upregulation of IGFBP-5 expression can reduce collagen synthesis and cartilage proliferation., Conclusions: PAPP-A2 may be involved in the development of the mouse hip joint by interfering the fibrous and cartilaginous metabolism via IGF pathway-associated proteins pathway.

Background and Objective: Hip dysplasia has been associated with risk factors such as breech presentation, female gender or family history. However, external factors, such as the use of baby carriers, seem to influence the development of the hip in the first months of life. The aim of this study is to evaluate the position of the hips of babies placed in different types of baby carriers by ultrasound image., Method: An ultrasound study of the hips of healthy babies between 1.5 and 3.5 months of age was carried out, when the children were carried in three different baby backpacks, which provide different degrees of support for the babies' thighs. All hips were typeI according to the Graf classification. Graf's alpha angle, acetabular coverage and distance to the pubis were assessed at baseline (examination table) and when the children were carried in the three different backpacks., Results: In all cases, the babies showed normal values in the three studied parameters, without statistically significant differences between any of the situations. There were also no differences in the ultrasound parameters related to the sex, age or weight of the baby., Conclusions: The right hip of the babies shows normal ultrasound parameters when placed in any of the baby carriers studied., (Copyright © 2019 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.)

Canine hip dysplasia and developmental dysplasia of the human hip share demographic, phenotypic, and clinical features including the predisposition to develop osteoarthritis in affected joints. To support the results of genetic mapping studies for CHD and its concomitant osteoarthritis with functional information, we performed RNA-seq on hip capsule and teres ligament of affected and unaffected dogs. RNA seq showed that expressed genes segregated according age, capsule or ligament, and hip phenotype. Expression of HHIP, DACT2, and WIF1 was significantly higher in capsule from control hips than dysplastic hips indicating a disruption of the hedgehog signaling pathway. Expression of SPON 1, a key component of the WNT pathway, was increased significantly in both dysplastic capsule and ligament while FBN2 and EMILIN3 were significantly increased in dysplastic capsule. Of genes associated with human hip osteoarthritis, expression of ACAN, IGF1, CILP2, COL11A1, COL8A1, and HAPLN was increased significantly in dysplastic capsule. The significant increase in expression of PLA2F, TNFRSF, TMEM, and IGFBP in dysplastic capsule indicated an injury response. Gene set enrichment analysis revealed that genes involved in extracellular matrix structure, epithelial to mesenchymal transition, myogenesis, growth factor signaling, cancer and immune pathways were enriched in dysplastic capsule. For teres ligament from dysplastic joints, genes in retinoic signaling pathways and those encoding extracellular matrix molecules, but not proteoglycans, were enriched. Hip tissues respond to abnormal mechanics early in dysplastic hip development and these pathways present targets for intervention in the early synovitis and capsulitis secondary to canine and human hip dysplasia. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:313-324, 2019., (© 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

We aimed to investigate the early radiological effects of Dega and Pemberton iliac osteotomies that were performed in patients aged 4-8 years with developmental dysplasia of the hip on development of hip joint. Dega osteotomy or Pemberton osteotomy was performed in 76 hips of 58 patients because of developmental dysplasia of the hip between September 2011 and June 2015 and were evaluated retrospectively. Of a total of 76 hips, Pemberton osteotomy was performed on 39 (19 unilateral) and Dega osteotomy was performed on 37 (21 unilateral). In all hips, the acetabular index, acetabular depth ratio, centre-edge angle of Wiberg, and Reimer's index values were recorded preoperatively and at the final follow-up. We measured the surface areas of the femoral head ossific nucleus in patients with unilateral dysplastic hips and compared results before both osteotomy procedures and at the final follow-up. There were no statistically significant differences between the groups in terms of the acetabular index and acetabular depth ratio values (P>0.05) preoperatively and at the final follow-up, but the mean centre-edge angle of Wiberg and Reimer's index values showed significant statistical differences in favor of the Dega procedure (P<0.05). There was a statistically significant difference in favor of the Pemberton procedure when the mean ratio of the surface area of the femoral head ossific nucleus on the dysplastic side in relation to the normal side was compared preoperatively (P=0.042) and at the final follow-up (P=0.027) in unilateral hips. Although Dega and Pemberton osteotomies produce satisfactory radiological outcomes at early stages in children aged 4-8 years with developmental dysplasia of the hip, a higher rate in the surface area of the femoral head ossific nucleus was observed in the Pemberton osteotomy group, which also had a lower mean age than the Dega osteotomy group.

Recently, more attention has been paid to the role of the acetabular labrum. Therefore, we designed a retrospective cohort study of patients with residual hip dysplasia (RHD) who underwent magnetic resonance imaging (MRI). The objective of this study was to investigate an association between the MRI appearance of the labrum before school age and the natural history of RHD.We retrospectively investigated 45 hips of 40 patients who underwent MRI at about 3 and 4 years of age for RHD and were conservatively followed up with until 6 years of age or older. We evaluated the extent of eversion with a new method that measures the β angle (MRI β angle) using landmarks of the Graf method on MRI T2*-weighted images. The outcome measure was the Severin classification at the final follow-up. We compared the radiographic and MRI parameters at approximately 3 and 4 years of age between the good and poor outcome groups. The Student t test or one-way analysis of variance was used to compare the quantitative variables between groups. The Chi-square test was used to perform a ratio comparison.Although there was a significant difference in the center-edge (CE) angle, there was no significant difference in the acetabular index and the ratio of the presence of femoral head necrosis and the break in Shenton line between the good and poor groups. The MRI β angle was significantly greater in the poor outcome group than in the normal and good outcome groups. The cut-off value of the MRI β angle to differentiate the good and poor outcome groups was 65°, and its specificity and sensitivity were 92% and 53%, respectively.There was labral eversion on MRI scans in patients with RHD. Acetabular development before adolescence was poorer with greater labral eversion on MRI scans. The specificity for poor acetabular development was high when the MRI β angle was 65° or more. The MRI β angle has the potential to predict acetabular development.

The mechanical loading environment influences the development and maturation of joints. In this study, the influence of imbalanced muscular loading on joint development was studied using localized chemical denervation of hip stabilizing muscle groups in neonatal mice. It was hypothesized that imbalanced muscle loading, targeting either gluteal muscles or quadriceps muscles, would lead to bilateral hip joint asymmetry, as measured by acetabular coverage, femoral head volume and bone morphometry, and femoral-acetabular shape. The contralateral hip joints as well as age-matched, uninjected mice were used as controls. Altered bone development was analyzed using micro-computed tomography, histology, and image registration techniques at postnatal days (P) 28, 56, and 120. This study found that unilateral muscle unloading led to reduced acetabular coverage of the femoral head, lower total volume, lower bone volume ratio, and lower mineral density, at all three time points. Histologically, the femoral head was smaller in unloaded hips, with thinner triradiate cartilage at P28 and thinner cortical bone at P120 compared to contralateral hips. Morphological shape changes were evident in unloaded hips at P56. Unloaded hips had lower trabecular thickness and increased trabecular spacing of the femoral head compared to contralateral hips. The present study suggests that decreased muscle loading of the hip leads to altered bone and joint shape and growth during postnatal maturation. Statement of Clinical Significance: Adaptations from altered muscle loading during postnatal growth investigated in this study have implications on developmental hip disorders that result from asymmetric loading, such as patients with limb-length inequality or dysplasia. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1128-1136, 2017., (© 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Background: Infants with a dislocated and unstable hip that does not lend itself to stabilisation may be treated using overhead traction to achieve gradual reduction of the hip joint. The aim of this paper was to analyse the radiological outcomes of overhead traction therapy and the effect of duration of traction on the occurrence of complications and final treatment outcomes. Material and methodd. A retrospective analysis of medical records of 26 children (34 affected hips) involved three independent observers assessing radiological parameters before the surgery and at follow-up visits at least two years after the therapy., Results: Overhead traction was used for an average of 35 days (range: 15-43 days). Twenty six hips were treated solely with reduction and immobilisation in a 'human position' plaster cast. Three hips were qualified for surgery immediately after a preliminary traction period. Five hips showed a suboptimal result following the immobilisation period. A MANOVA model revealed that the following factors had a significant effect on the treatment outcome: superior centring ratio of Smith (with the lowest values recorded in patients with residual hip dysplasia, p = 0.001) and acetabular angle of Sharp (with the lowest values found in patients requiring surgery, p = 0.01). Statistical tests did not show a correlation between the duration of traction and disturbance of proximal femoral metaphysis growth assessed according to Bucholz and Ogden classification. Fifteen hips were classified as type I, eight hips were graded as type II and also eight hips as type III., Conclusions: The lowest values of acetabular angle of Sharp were recorded in patients requiring surgery and the lowest superior centring ratio of Smith was found in those with residual hip dysplasia. The duration of overhead traction did not directly correlate with the final outcome; it only seemed to be an indicator of the severity of hip dysplasia. Routine use of overhead traction before undertaking closed reduction does not probably decrease the incidence of proximal femoral growth disturbance.

Objectives: This study examines the relationship between the morphology of the lumbosacral transitional vertebra (LTV) and asymmetrical development of the hip joints in dogs., Methods: A total of 4000 dogs which had been consecutively scored for canine hip dysplasia were checked for the presence of a LTV. A LTV was noted in 138 dogs and classified depending on the morphology of the transverse processes and the degree of contact with the ilium., Results: In dogs with an asymmetrical LTV, the hip joint was significantly more predisposed to subluxation and malformation on the side of the intermediate or sacral-like transverse process (p <0.01), on the side of the elevated pelvis (p <0.01), or when an asymmetrical LTV resulted in pelvic rotation on its long axis (p <0.01), whereas hip joint conformation was less affected on the side featuring a free transverse process (p <0.01)., Clinical Significance: The results support our hypothesis that an asymmetrical LTV favours pelvic rotation over its long axis, resulting in inadequate femoral head coverage by the acetabulum on one side. Inadequate coverage of the femoral head favours subluxation, malformation of the hip joint, and secondary osteoarthritis. Asymmetrical hip conformation may therefore be the sequela of a LTV and mask or aggravate genetically induced canine hip dysplasia.

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., (© 2016 Wiley Periodicals, Inc.)

Objectives: This study aims to evaluate the relationship of early-term radiological changes with development of the hip joint after Pemberton osteotomy., Patients and Methods: This study, which was conducted between January 2010 and December 2014, included 101 hips (26 bilateral) of 75 patients (25 males, 50 females; mean age 31.5 months; range 15 to 71 months) which were performed Pemberton osteotomy due to developmental dysplasia of the hip. Radiologically, we assessed the parameters of center-edge angle, acetabular index (AI), and acetabular depth index (ADI). We measured the surface area of the femoral head ossific nucleus on anterior-posterior pelvic X-rays. We graded the degree of hip dislocation according to Tönnis classification while the femoral head avascular necrosis was graded according to Kalamchi-MacEwen classification. We separated the operated hips in all patients and in only unilaterally operated patients in three groups according to their follow-up durations as 12 months, 12 to 24 months, and more than 24 months. We analyzed the associations of radiological parameters in all follow-up durations., Results: Mean follow-up duration was 22.5 months (range, 6 to 66 months). Preoperative mean AI was 42.25° (range, 29° to 60°) and last follow-up mean AI was 20.45° (range, 10° to 32°). Preoperative mean ADI was 16.48° (range, 9°-30°) and last follow-up mean ADI was 26.1° (range, 23°-47°). Sixty hips were Tönnis type 4, 26 hips were type 3, and 15 hips were type 2. According to follow-up duration classification; there were 32 hips (21 unilateral) with 12 month-follow-up, 43 hips (17 unilateral) with 12-24 month-follow-up, and 26 hips (11 unilateral) with more than 24-month follow-up. We applied shortening osteotomy to 18 femurs. According to Kalamchi-MacEwen classification; avascular necrosis type 1 was present in 16 hips, type 2 in two hips, type 3 in three hips, and type 4 in two hips. We performed revision operations for five hips because of recurrent subluxations., Conclusion: We observed progressive improvements in hip joints and consequently in radiological parameters in the early-term after Pemberton osteotomy.

Purpose: Early identification and intervention with conservative measures is important to help manage hip dysplasia in children with a high adductor and iliopsoas tone and delay in weight bearing. The effect of a daily standing program with hip abduction on hip acetabular development in ambulatory children with cerebral palsy was studied., Method: The participants were 26 children with spastic diplegia cerebral palsy (CP), classified at Level III according to the Gross Motor Function Classification System (GMFCS). Thirteen children stood with hip abduction at least 1 h daily from 12 to 14 months of age to 5 years with an individually fabricated standing frame with hip abduction., Results: At the age of 5 years, radiologic results of the study group were compared with a comparison group of 13 children with spastic diplegia CP who had not taken part in a standing program. The migration percentage in all children who stood with abduction remained within stable limits (13-23%) at 5 years of age, in comparison to children who did not stand in abduction (12-47%) (p < 0.01)., Conclusions: The results indicate that a daily standing program with hip abduction in the first 5 years may enhance acetabular development in ambulatory children with spastic diplegia CP., Implications for Rehabilitation: Abnormal acetabular development is a problem related to mobility problems and spasticity muscles around the hip. The literature suggests that postural management and standing programs could reduce levels of hip subluxation and increase function in children with cerebral palsy. A standing program with hip abduction can be a beneficial to develop more stable hips in children with spastic diplegic GMFCS level III.

The recognition of hips at risk of displacement in children with cerebral palsy (CP) is a difficult problem for the orthopaedic surgeon. The Gross Motor Function Classification System (GMFCS) and head-shaft angle (HSA) are prognostic factors for hip displacement. However, reference values for HSA are lacking. This study describes and compares the development of HSA in normal hips and children with CP. We selected 33 children from a retrospective cohort with unilateral developmental dysplasia of the hip (DDH) (five boys, 28 girls) and 50 children (35 boys, 15 girls) with CP with GMFCS levels II to V. HSA of normal developing hips was measured at the contralateral hip of unilateral DDH children (33 hips) and HSA of CP children was measured in both hips (100 hips). Measurements were taken from the radiographs of the children at age two, four and seven years. The normal hip HSA decreased by 2° per year (p < 0.001). In children with CP with GMFCS levels II and III HSA decreased by 0.6° (p = 0.046) and 0.9° (p = 0.049) per year, respectively. The HSA did not alter significantly in GMFCS levels IV and V. Between the ages of two and eight years, the HSA decreases in normal hips and CP children with GMFCS level, II to III but does not change in GMFCS levels IV to V. As HSA has a prognostic value for hip displacement, these reference values may help the orthopaedic surgeon to predict future hip displacement in children with CP., (©2015 The British Editorial Society of Bone & Joint Surgery.)

Background: Coxa valga is a common clinical feature of hereditary multiple exostoses (HME). The current study aimed to determine the unique developmental pattern of the hip in patients with HME and evaluate the factors that influence its progression., Methods: Thirty patients (57 hips) with HME were divided into two groups according to the Hilgenreiner epiphyseal angle (HEA). Twenty-two patients (44 hips) including 13 men and 9 women were assigned to group 1 (HEA <25°), and 8 patients (13 hips) including 3 men and 5 women were assigned to group 2 (HEA ≥25°). The mean age at the initial presentation was 6.0 (4-12) years with 6.8 (4-11) years of follow-up in group 1, and 10.4 (8-13) years with 5.4 (2-9) years of follow-up in group 2. We measured the HEA, neck-shaft angle (NSA), acetabular index (AI), center-edge angle (CEA), and migration percentage (MP) for radiographic evaluation., Results: Among the hips, 50 (87.7%) hips had coxa valga and 27 (47.4%) hips had abnormal MP (42.1% were borderline and 5.3% were subluxated). There was a significant difference in the HEA and NSA between the groups (p < 0.001 and p < 0.05, respectively). The HEA significantly correlated with the development of the NSA and no correlation was found between the HEA and AI, CEA, and MP., Conclusions: There was a significant relationship between the HEA at the initial presentation and the NSA at skeletal maturity. We should consider guided growth for patients with lower HEA to prevent significant coxa valga deformity with close follow-up.

Objective: To evaluate associations of measures assessed by radiography, 2-D CT, and 3-D CT of the hip joints of immature dogs with osteoarthritis in the same joints at maturity., Animals: 46 hound-type dogs from a colony predisposed to osteoarthritis., Procedures: Images of hip joints (1/dog) were obtained at 16, 32, and 104 weeks of age. Radiographic measures included Norberg angle, distraction index, and osteoarthritis score. Two-dimensional CT measures included acetabular index, percentage of femoral head coverage, and center edge, horizontal toit externe, acetabular anteversion, and ventral, dorsal, and horizontal acetabular sector angles. Three-dimensional CT measures were femoral head and neck volume, femoral neck angle, and femoral head and neck radius. Differences among measures at 16 and 32 weeks in dogs with different osteoarthritis scores at later time points, relationships among variables at each time point, and relationships of single and combined measures with the presence of osteoarthritis at 104 weeks were evaluated., Results: The 16- and 32-week distraction index, center edge angle, dorsal acetabular sector angle, horizontal acetabular sector angle, percentage of femoral head coverage, acetabular index, and Norberg angle and the 32-week femoral neck angle varied significantly with osteoarthritis severity at 104 weeks. Presence of osteoarthritis in mature dogs was most strongly associated with 16-week combined measures of distraction index and center edge angle and 32-week combined measures of dorsal acetabular sector angle and Norberg angle., Conclusions and Clinical Relevance: Changes in hip joint morphology associated with radiographic signs of osteoarthritis were detectable as early as 16 weeks of age and varied with osteoarthritis severity in adult dogs. The use of combined hip joint measures may improve early identification of dogs predisposed to hip joint osteoarthritis.

Context: Calcium intake during growth is essential for future bone health but varies widely between individuals and populations. The impact on bone of increasing calcium intake is unknown in a population where low calcium intake, stunting, and delayed puberty are common., Objective: To determine the effect of prepubertal calcium supplementation on mean age at peak velocity for bone growth and mineral accrual., Design and Setting: Prospective follow-up of boys in rural Gambia, West Africa, who had participated in a double-blind, randomized, placebo-controlled trial of calcium supplementation., Participants: Eighty boys, initially aged 8.0-11.9 years, were followed up for 12 years., Interventions: Subjects received 1 year of calcium carbonate supplementation (1000 mg daily, 5 d/wk)., Main Outcome Measures: Dual-energy x-ray absorptiometry measurements were carried out for whole body (WB), lumbar spine, and total hip bone mineral content, bone area (BA), and WB lean mass. Super imposition by translation and rotation models was made to assess bone growth., Results: Age at peak velocity was consistently earlier in the calcium group compared to the placebo group, for WB bone mineral content (mean, -6.2 [SE, 3.1]; P = .05), WB BA (mean, -7.0 [SE, 3.2] mo; P = .03), lumbar spine and total hip BA. By young adulthood, supplementation did not change the amount of bone accrued (mineral or size) or the rate of bone growth., Conclusions: Twelve months of prepubertal calcium carbonate supplementation in boys with a low calcium diet advanced the adolescent growth spurt but had no lasting effect on bone mineral or bone size. There is a need for caution when applying international recommendations to different populations.

To provide the best possible care to patients with developmental dysplasia of the hip, it is helpful to understand the normal growth and development of the hip joint; the pathoanatomy, epidemiology, and diagnosis of the condition; and the natural history of a missed diagnosis of dislocation, subluxation, and dysplasia.

Ideally, developmental dysplasia of the hip is treated early in childhood by nonsurgical methods. If these methods are ineffective, surgical reduction in a nonambulating child is required. A young child (age 6 to 18 months) who requires surgical reduction can be treated by formal anterior open reduction or by the medial Ludloff approach to the hip. Additional bony procedures are usually not required in these young patients. Delayed diagnosis is still common, requiring surgical reduction for children of walking age. These older children usually require formal open reduction (anterior approach) plus an associated bony osteotomy (acetabular, proximal femoral, or, in some cases, both types of osteotomies) to better stabilize the hip. The addition of a proximal femoral derotational shortening osteotomy for open reduction in older children was first used in children older than 3 years, but now it is commonly used in children as young as 2 years. This osteotomy decreases the forces on the reduced hip and minimizes the chances for redislocation and osteonecrosis. In all surgical procedures for developmental dysplasia of the hip, the surgeon must avoid too great a focus on bony osteotomies because the management of soft-tissue abnormalities is critical in achieving a stable reduction.

The current treatment of painful hip dysplasia in the mature skeleton is based on acetabular reorientation. Reorientation procedures attempt to optimize the anatomic position of the hyaline cartilage of the femoral head and acetabulum in regard to mechanical loading. Because the Bernese periacetabular osteotomy is a versatile technique for acetabular reorientation, it is helpful to understand the approach and be familiar with the criteria for an optimal surgical correction. The femoral side bears stigmata of hip dysplasia that may require surgical correction. Improvement of the head-neck offset to avoid femoroacetabular impingement has become routine in many hips treated with periacetabular osteotomy. In addition, intertrochanteric osteotomies can help improve joint congruency and normalize the femoral neck orientation. Other new surgical techniques allow trimming or reducing a severely deformed head, performing a relative neck lengthening, and trimming or distalizing the greater trochanter.  An increasing number of studies have reported good long-term results after acetabular reorientation procedures, with expected joint preservation rates ranging from 80% to 90% at the 10-year follow-up and 60% to 70% at the 20-year follow-up. An ideal candidate is younger than 30 years, with no preoperative signs of osteoarthritis. Predicted joint preservation in these patients is approximately 90% at the 20-year follow-up. Recent evidence indicates that additional correction of an aspheric head may further improve results.

Developmental dysplasia of the hip represents a spectrum of disease ranging from transient neonatal instability to established dislocation. It is accepted that female sex, breech presentation, and family history are risk factors for the disease. Early diagnosis by clinical examination or ultrasound imaging is emphasized, with splint treatment ideally commencing by 6 weeks of age. Treatment using the Pavlik harness is successful in up to 90% of patients. Ultrasound imaging is the gold standard for monitoring a patient during harness wear. Failed splintage or late presentation usually necessitates surgical intervention depending on the patient's age and the severity of the hip dysplasia and displacement.

Background: Elite-level sports activities have been associated with hip osteoarthritis and cam-type deformity., Purpose: To analyze the appearance and prevalence of an abnormal cam-type deformity of the proximal femur and its potential association to hip pain in adolescent and young adult athletes., Study Design: Cross-sectional study; Level of evidence, 3., Methods: A total of 77 elite-level male ice hockey players were evaluated with a questionnaire, clinical examination, and magnetic resonance imaging. The questionnaire and clinical examination were used to determine whether the hip being evaluated was symptomatic and what the internal rotation of the hip was. Magnetic resonance imaging was used to determine physeal status (open/closed) and α angle of the cranial half of the proximal femur using a standard clockface system., Results: The mean age of the patients was 16.5 years (range, 9-36 years); 15 of 77 (19.5%) athletes had a history of hip pain and a positive impingement test finding. The α angles were higher in athletes with closed physes versus open physes (58° vs 49°, respectively; P < .001). Symptomatic athletes had higher α angles compared with asymptomatic athletes at the 12-o'clock (52° vs 46°, respectively; P = .022), 1-o'clock (62° vs 52°, respectively; P < .001), and 2-o'clock (59° vs 50°, respectively; P < .001) positions. Internal rotation was significantly decreased in symptomatic compared with asymptomatic athletes (17° vs 23°, respectively). Higher α angles in the anterosuperior quadrant were significantly associated with decreased internal rotation., Conclusion: The data suggest that playing ice hockey at an elite level during childhood is associated with an increased risk for cam-type deformity and hip pain after physeal closure.

The pathogenesis and clinical course of hip dysplasia in cerebral palsy and Down syndrome is different than idiopathic developmental dysplasia of the hip. Unlike idiopathic developmental hip dysplasia, hip development in cerebral palsy and Down syndrome is typically normal in utero and instability develops after birth secondary to musculoskeletal disorders associated with the disease condition. For this reason, treatment protocols in Down syndrome and cerebral palsy hip dysplasia differ greatly from protocols designed to treat idiopathic hip dysplasia. The purpose of this review is to describe the pathologic hip morphology that results from cerebral palsy and Down syndrome.

Several authors have suggested that the final five weeks of gestation are a critical period for the development of the hip. In order to test the hypothesis that gestational age at birth may influence the development of the hip joint, we analysed the sonographic findings in 1992 hips (in 996 term newborns) with no risk factor for developmental dysplasia of the hip. The 996 infants were born at a mean gestational age of 39 weeks (37 to 41). The mean bony roof angle (α), cartilage roof angle (β) and the distribution of the type of hip were compared between the 37th, 38th, 39th, 40th and 41st birth week groups. There was a significant difference in the distribution of type of hip between the different birth week groups (p < 0.001), but no significant difference between the α angles of all groups (p = 0.32). There was no correlation between birth week and roof angle (p = 0.407 and p = 0.291, respectively) and no significant correlation between birth weight and roof angle (p = 0.735 and p = 0.132, respectively). The maturity of the infant hip, as assessed sonographically, does not appear to be affected by gestational age, and the fetal development of the acetabular roof appears to plateau from 37 weeks.

The purpose of this study is to investigate whether the dynamic hip immobilization is more favourable for lessening ischemic injury to the immature femoral head than a static immobilization. 152 Japanese white rabbits were divided into four groups randomly, and the hips were immobilized into "human" position (group A), "frog leg" position (group B) and "dynamic frog leg" position (group C). Group D was used as control. Ten rabbits in each group were killed, and the hip specimens were harvested at 1, 2, and 3 weeks after immobilization. Bcl-2/Bax expression balance and chondrocytes apoptosis were analyzed. The remaining eight rabbits in each group were used to measure the blood supply of capital femoral epiphysis by selective vascular perfusion with Indian ink. The Bcl-2/Bax expression ratio in group C was significantly increased than that in group A and B (p<0.001), while that was not significantly different from control group (p=0.0592). At three weeks after immobilization, the average apoptotic ratio was 36.7%, 45.8%, and 26.7% in group A, B and C, respectively (p<0.01). There was no significant difference between group C and normal control (p=0.0597). The perfusion ratio was 0.03±0.03, 0.03±0.02, and 0.08±0.03 in group A, B and C respectively, and 0.12±0.04 in control group (p<0.05). Thus, the dynamic immobilization model exhibited a relatively less chondrocytes apoptosis and disturbance to the femoral head perfusion than other immobilizations in vivo, which therefore may be useful for reducing avascular necrosis following the treatment of developmental dysplasia of the hip.

The purpose of this study was to investigate the development of the osseous acetabular index (OAI) and cartilaginous acetabular index (CAI) using MRI. The OAI and CAI were measured on the coronal MR images of the hip in 81 children with developmental dysplasia of the hip (DDH), with a mean age of 19.6 months (3 to 70), and 241 normal control children with a mean age of 5.1 years (1 month to 12.5 years). Additionally the developmental patterns of the OAI and CAI in normal children were determined by age-based cross-sectional analysis. Unlike the OAI, the normal CAI decreased rapidly from a mean of 10.17° (sd 1.60) to a mean of 8.25° (sd 1.90) within the first two years of life, and then remained constant at a mean of 8.04° (sd 1.65) until adolescence. Although no difference in OAI was found between the uninvolved hips in children with unilateral DDH and normal hips (p = 0.639), the CAI was significantly different between them both (p < 0.001). The normal CAI has fully formed at birth, and is maintained constantly throughout childhood. The CAI in the unaffected hips in children with unilateral DDH is also mildly dysplastic.

Background: Shelf acetabuloplasty has the potential to cause iatrogenic acetabular growth arrest, although accelerated acetabular growth has been reported based on plain radiographic evaluations in patients with Legg-Calvé-Perthes disease. Because plain radiographs may be limited in depicting actual acetabular morphology, it is unclear whether there are growth disturbances., Questions/purposes: We therefore determined (1) whether focal or generalized acetabular growth stimulation or retardation occurred based on CT analysis in combination with plain radiographic assessment; and (2) whether radiographically assessed femoral head deformity, subluxation, and acetabular dysplasia were associated with residual zonal rim dysplasia of the acetabulum., Methods: We examined 14 patients who had undergone shelf acetabuloplasty for "reducible subluxation" and underwent CT scans at a mean 7 years after surgery (range, 3-11 years). We measured radiographic indices reflecting acetabular depth and rim dysplasia on multiplanar reformatted images in 10 radial planes and on plain radiographs and calculated their operation-to-control ratios to assess growth changes. The mean age at surgery was 9.3 years (range, 7-12 years)., Results: We observed generalized accelerated growth in 11 hips and equivocal growth in three. None of the 14 hips showed an abrupt change in acetabular geometry. Despite improved acetabular depth in all hips, eight hips had focal rim dysplasia in the superior zone on CT examinations, and this was associated with a smaller center-edge angle, a greater deformity index, and preexisting acetabular dysplasia., Conclusions: Our observations support the notion that shelf acetabuloplasty has a favorable, stimulatory effect on acetabular growth. However, the possible persistence of preexisting zonal rim dysplasia should be considered.

Purpose: The aim of this study was to analyse the results of treatment of sonographically diagnosed type IIb developmental hip dysplasia and to identify residual hip dysplasia using clinical and radiological assessment., Methods: We retrospectively reviewed the data of 49 children (59 type IIb and 39 type I hips, according to Graf's monographic classification) treated in abduction braces. The mean age was 9.1 years (range 4-15) at latest follow-up., Results: According to the clinical classification of Mckay in Barrett's modification, all the type I and type IIb hips had very good results. No statistical differences were found between type I and IIb hips when comparing both measured radiological parameters and radiological results according to the Severin classification at latest follow-up. Using our criteria (two or more radiological parameters were outside of their normal range), 12 out of 49 type IIb hips demonstrated persistent dysplasia. Of the 12 hips, eight sonograms were normal at the end of treatment and four patients failed to normalise. No type I hips demonstrated two or more abnormal radiographic parameters at latest follow-up., Conclusions: Despite obtaining normal sonograms at the end of treatment, some children with type IIb dysplasia may demonstrate radiographic evidence of persistent hip dysplasia over a longer follow-up period. Our results suggest that these children should be monitored until skeletal maturity.

Aim: To determine whether there is a seasonal variation in the phenotypic hip score of dogs born in New Zealand as assessed by the New Zealand Veterinary Association (NZVA) canine hip dysplasia (CHD) scheme., Methods: Data from dogs born in New Zealand between 1988 and 2009 that have been scored for CHD were retrospectively evaluated for the effect of month of birth on radiographic phenotype. Data included both the total score and the subtotal score, comprising Norberg's angle, the subluxation score and changes to the cranial acetabular edge, for each dog. Datasets were created for all breeds combined and for the four most populous breeds using the scheme (German Shepherd dog, Labrador Retriever, Golden Retriever and Rottweiler) and stratified according to month of birth and season. Due to the skewed nature of the data, a Kruskal-Wallis Rank Sum test was used to test for statistical significance. Additionally, χ² analysis was performed using the median of each dataset (proportion above/below the median). The null hypothesis was that there would be no effect of month of birth, and hence seasonality, on hip phenotype for dogs born and scored in New Zealand by the NZVA., Results: For all breeds combined, month of birth had an effect on total and subtotal NZVA CHD scores (p<0.001) with a lower total hip score in the autumn months of March and April than other months. When individual large breed data were analysed, there was an effect of month of birth on total and subtotal scores for the Labrador Retriever and the Rottweiler (p ≤ 0.05), but not the German Shepherd dog or Golden Retriever breeds., Conclusions: Being born in the autumn was associated with a protective effect on hip phenotype in some breeds. These results suggest that weather and/or another seasonal factor may have a significant environmental effect on the phenotype of the coxofemoral joint., Clinical Relevance: The protective effect of being born in autumn suggests that a decreased level of exercise during subsequent development over winter may positively impact on final coxofemoral joint conformation. Whilst statistically significant, the magnitude of the sparing effect is not likely to be clinically relevant. However, this study, in concert with other studies, may suggest that the effects of exercise can be manipulated to improve hip phenotype.

Dual-energy X-ray absorptiometry hip scans of 1,760 population-based Caucasians, 599 girls and 642 boys aged 6-19 years and 270 women and 249 men aged 20-90 years, were analyzed with the hip structural analysis (HSA) software to present age- and sex-specific normative HSA data of the femoral neck (FN). Measured traits included bone mineral density (BMD), cross-sectional area (CSA), section modulus (Z), periosteal diameter (PD), endosteal diameter (ED), cortical thickness (CT), and cross-sectional moment of inertia (CSMI). When plotting the measured traits versus age, the curves increased with higher ages until statistically significant break points were reached, for all traits at age 17 in girls and age 19 in boys. After the break points, PD and ED increased with higher ages but, as ED increased more than PD, BMD and CT decreased significantly with higher ages. The decline in BMD was counteracted by the increase in bone size so that there was only a nonstatistically significant decrease in bone strength, estimated as Z and CSMI, from break point to age 90. The partial preservation of bone strength was more obvious in men than in women as the decline in BMD was higher in women than in men, while the expansion in PD was larger in men than in women. The sex difference in the normative FN bone strength data seems to be related to sex discrepancies in the development of both bone mass and geometrical parameters during both growth and adulthood.

Purpose: The purpose of this study was to simplify and enhance the ultrasound (US) analysis of the infant's hip by introducing a novel parameter named "L value" into the widely used Graf method., Methods: We analysed 508 ultrasonographic images of the hips in infants aged three months. The images were first evaluated using the Graf measurements. On the same images, two additional measurements were performed in order to define the new parameter that was named L value. The threshold values of the new L value were identified based on the highest specificity as well as sensitivity for discrimination between the Graf groups. Those values were then used in order to reclassify the hips into three simplified groups. Inter-observer agreement was estimated by Cohen's kappa coefficient., Results: The threshold values for the L value between Graf groups Ia and Ib was 0.46, between Ib and IIb was 0.68 and between IIb and IIc was 0.92. Correlation analysis between Graf's classification and the values of the L value was performed and was proved to be statistically significant, r = 0.49; p < 0.001. After simplifying the classification into three newly defined groups of patients depending on the degree of hip development, the correlation coefficient was much higher, r = 0.94, r (2) = 0.88 for p < 0.001. Inter-observer agreement for the L value was substantial., Conclusions: The new L value parameter in Graf's ultrasound hip evaluation enables a faster, simpler, more reliable and more unbiased classification for developmental dysplasia of the hip as the L value changes proportionally with the hip maturity.

Developmental dysplasia of the hip can arise in utero due to a dislocating posture, sometimes associated with predisposing genetic factors. The ideal time for diagnosis is during the neonatal period and adequate screening procedures must be in place. Indeed, the plasticity of hyaline cartilage and fibrocartilage combined with the growth potential at this age nearly always result in rapid complete resolution of the deformity. Ultrasound, when indicated, is the best imaging modality for diagnostic confirmation. It allows evaluation of the osteocartilaginous structures, joint space and soft tissues. Ultrasound provides the clinician with a reliable morphologic and dynamic evaluation tool improving the diagnostic accuracy and guiding orthopedic treatment. Our experience, dating back to 1985, is based on a population imaged between 2007 and 2009. From a total of 2480 neonates screened because of abnormal finding or risk factors, we identified 257 cases of dislocation (10%) in 191 neonates : 14 cases of nonreducible dislocation (10 neonates), 30 cases of reducible hip dislocation (24 neonates), 97 cases of dislocatable hip (73 neonates) and 116 cases of subluxable hip (84 neonates). Clinical and sonographic follow-up demonstrated therapeutic success in 237 cases (93%) and failure in 20 cases (one case of subluxable hip, two cases of dislocatable hip, three cases of dislocated hip, 14 cases of nonreducible hip dislocation). Imaging follow-up (6 to 24 months) showed asymmetry in the size of the proximal femoral epiphyses in 20 cases (with resolution in 10 cases), three cases of dysplasia and one case of post-reduction osteochondritis., (Copyright © 2010. Published by Elsevier Masson SAS.)

Pediatric proximal femur dual-energy X-ray absorptiometry (DXA) scans present analytic challenges because of the lack of standard points of reference in the growing skeleton. The Iowa Bone Development Study (IBDS) developed a modified pediatric-specific proximal femur analysis protocol using Hologic software. Serial DXA measurements were obtained for 214 children at approximate ages 5, 8, 11, and 13 yr. Standard analysis procedures as described by the manufacturer (Hologic default) were compared with the IBDS protocol. The IBDS protocol yielded lower but more stable results for bone area, bone mineral content (BMC), and bone mineral density for total hip, femoral neck, trochanter, and intertrochanter as a result of more precisely controlling the regions of interest. Linear regression models with body size, age, and gender as predictors were developed to examine variation in measurements. Coefficients of determination (R(2)) with the IBDS protocol were greater for each time point, demonstrating that the modified protocol was better aligned with body size. Similarly, Spearman correlation coefficients between total hip and hip subregions were consistently higher for BMC and bone area with the IBDS protocol with differences more notable among younger children. The IBDS protocol provides a reproducible method for evaluating pediatric proximal femur DXA scans during growth., (Copyright © 2010 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.)

Background: Disturbed muscle balance in the hip joints of children with cerebral palsy (CP) shifts the pivoting point from the middle of the femoral head to the lesser trochanter. Forces that dislocate the femoral head progressively change acetabular shape, producing inadequate femoral head covering. The aim of the study was to carry out a radiological evaluation of hip congruency in children with CP after surgical treatment., Material and Methods: The study group consisted of CP patients operated on due to lower limb dysfunction between 1988 and 2001. All patients had undergone multilevel soft tissue release. A total of 52 children reported for follow-up examinations. There were 18 patients with hemiparesis (32%), 19 with diparesis (36%), and 15 with tetraparesis (29%). The age at surgery was between 2 and 19 y.o. (average age 7.33 y.o.). Radiological evaluation of the hip joints focused on changes in the migration index and the shaft-neck angle., Results: The mean migration index before surgery was 30.4% in the group of diparetic and tetraparetic children. At the last follow-up examination, the average migration index was 32.5% on the right side and 25.6% on the left side (p>0.05). There was a statistically significant decrease in the value of the migration index in children operated on before the age of 8 years (p=0.007). In children operated on after the age of 8, the change in the migration index value did not exceed 0.5% (p>0.05)., Conclusions: 1. The mean migration index did not change significantly in the study group of surgically treated CP children. 2. Surgery had no influence on the shaft-neck angle 3. Surgery prevented progression of the migration index.

Objectives: To evaluate distinctive features of pelvis and hip joint development of English Bulldogs throughout the first year of life., Methods: The pelves of 20 English Bulldogs were radiographed at three different ages (<4, 6-8, and 12-14 months). At each time point, the dogs were clinically evaluated and the abnormal hip joints were classified as mild, moderate, or severely deformed. The pelves were compared to a phantom study in which external rotation of a normal hemipelvis around its long axis was artificially created at different degrees, with different pelvic inclinations, and classified as either normal and without deformity, or as mild, moderate, or severely deformed. Hip joints and pelvic scores were statistically compared., Results: Although none of the dogs were considered lame at the end of the study, none of the hips showed normal development; 77.5% were moderately to severely deformed at 12-14 months of age. At this age, 75% of the hemipelves had moderate to severe torsional deformity (>5.2 degrees of external rotation), with retroversion of the acetabulum confirmed by the presence of the crossover sign. An external rotation of the hemipelvis on its long axis >5 degrees was likely associated with a moderate to severely altered hip joint conformation., Clinical Significance: Abnormal hip conformation was common in this series of English Bulldogs. Torsional deformity of the pelves with acetabular retroversion was a common and distinctive feature, which has not yet been thoroughly studied in dogs. These findings need further evaluation in English Bulldogs as well as in other breeds.

The existing studies on the development of the hip joint predominantly focus on either the acetabulum or the proximal femur. This paper investigates the parallel geometrical development of both, the proximal femur and the acetabulum during growth. Six hundred and seventy-five hips with an age from 9 months to 16 years were studied by means of planimetric radiography; angles and lever arms were determined. Although the apophyseal angles remain virtually unchanged throughout growth, the epiphyseal angles and the neck-shaft angle undergo typical changes until the age of 10 years. Subsequently, there are no major changes in the angular conformation of the proximal femur, whereas acetabular coverage and its centric alignment continue to develop further until the end of skeletal growth. The load and muscle lever arms increase until the end of growth with their ratio remaining constant after the age of 10 years. We present correlated data on the geometrical development of the acetabulum and the proximal femur. The interpretation of our findings is to some extent limited by the two-dimensionality of planimetric radiography. Our results do, however, support the timing of corrective osteotomies of the proximal femur relatively soon after the age of 10 years.

The morphogenesis, remodeling, and degeneration of diarthroidial joints are directly under the control of the loading histories created by the musculoskeletal system during development and aging. The altered loading histories in individuals with cerebral palsy (CP) lead to aberrations in joint morphogenesis and an acceleration of joint degeneration. To understand this process in the hip, the normal ontogeny of the hip joint is reviewed with special attention to the mechano-biological factors associated with joint morphogenesis, endochondral ossification, and cartilage degeneration. A contrast is then made with the mechano-biological alterations observed with CP and the consequent influence on joint destruction. The features of the pathogenesis are: (1) altered muscular activity and restricted range of motion result in abnormal joint morphology, subluxation, and poor coverage of the femoral head; (2) joint incongruities created in early development cause local stress concentrations that can mechanically damage the articular cartilage; (3) the reduced magnitudes of muscular forces reduce the contact pressures at the joints, creating thinner cartilage and osteopenia; and (4) the thinner cartilage degenerates early, and subchondral bone collapse further contributes to the mechanical destruction of the remaining cartilage.