Smaller epiphyseal tubercle in hips with slipped capital femoral epiphysis compared to the uninvolved contralateral hip.

Recent investigations suggest that physeal morphologic features have a major role in the capital femoral epiphysis stability and slipped capital femoral epiphysis (SCFE) pathology, with a smaller epiphyseal tubercle and larger peripheral cupping of the femoral epiphysis being present in hips with progressive SCFE compared to healthy controls. Yet, little is known on the causal versus remodeling nature of these associations. This study aimed to use preoperative magnetic resonance imaging (MRI) of patients with unilateral SCFE to perform a comparison of the morphology of the epiphyseal tubercle, metaphyseal fossa, and peripheral cupping in hips with SCFE versus the contralateral uninvolved hips. Preoperative MRIs from 22 unilateral SCFE patients were used to quantify the morphological features of the epiphyseal tubercle (height, width, and length), metaphyseal fossa (depth, width, and length), and peripheral cupping height in three dimension. The quantified anatomical features were compared between hips with SCFE and the contralateral uninvolved side across the whole cohort and within SCFE severity subgroups using paired t-test. We found significantly smaller epiphyseal tubercle heights (p < 0.001) across all severities of SCFE when compared to their uninvolved contralateral side. There was a marginally smaller metaphyseal fossa length (p = 0.05) in SCFE hips compared to their contralateral uninvolved hips, with mild SCFE hips specifically having smaller fossa and epiphyseal lengths (p < 0.05) than their contralateral uninvolved side. There were no side-to-side differences in any other features of the epiphyseal tubercle, metaphyseal fossa and peripheral cupping across all severities (p > 0.05). These findings suggest a potential causal role of epiphyseal tubercle in SCFE pathogenesis.

"Slipped capital femoral epiphysis in a 25-year-old hypogonadic man with a large cranial chondroma: causality or coincidence? ".

BACKGROUND: Slipped capital femoral epiphysis (SCFE) is a hip disorder frequently occurring in adolescence. In adults it is rare and so far very few cases have been documented. CASE PRESENTATION: This report presents a 25-year-old patient diagnosed with an anterior fossa giant chondroma, hypogonadotropic hypogonadism, and SCFE. The patient underwent surgical and hormonal therapy. His symptoms revealed, and he became a father. CONCLUSIONS: Every patient diagnosed with SCFE in adulthood should undergo endocrinological assessment based on physical examination and laboratory tests.

Patients With Symptomatic Sequelae of Slipped Capital Femoral Epiphysis Have Advanced Cartilage Wear at the Time of Surgical Intervention.

BACKGROUND: Slipped capital femoral epiphysis (SCFE) is a common hip problem in children. The resulting deformity can cause impingement similar to cam-type idiopathic femoroacetabular impingement (FAI). Although there are similarities between FAI and SCFE, deformity patterns, severity, and time of onset of symptoms varies, which may impact management. The purpose of this study was to describe patterns of articular cartilage damage in patients undergoing surgical hip dislocation for sequelae of SCFE in comparison to patients undergoing arthroscopic surgery for primary FAI. METHODS: Patients were identified who underwent surgical treatment for hip pain due to primary FAI (cam type) or sequelae of SCFE. Clinical data and radiographic measurements were recorded. Cartilage was assessed intraoperatively. Severity was classified using the modified Beck classification, while location was classified into 6 sectors. Statistical analysis was performed to test for differences in demographic and radiographic characteristics between the SCFE and FAI patients. χ2 or Fisher exact tests were used to evaluate trends in patterns of acetabular and femoral cartilage wear between SCFE and FAI groups. RESULTS: The SCFE group had 28 hips compared with 304 in the FAI group. SCFE patients were younger (19 vs. 32, P<0.001), had higher body mass index (30±5.9 vs. 24±4.8, P<0.001), and were more often male (61% vs. 27%, P<0.001). Deformity severity based on α-angle was higher in the SCFE group [AP 74 vs. 55 (P=0.001) and Dunn 72 vs. 58 (P<0.001)]. There were no significant differences with regards to lateral center edge angle, anterior center edge angle, or Tonnis angle. In both groups the most common locations for cartilage lesions in both groups were the anterior peripheral and superolateral peripheral regions with fewer but more widely distributed femoral head lesions. The SCFE group had higher rates of femoral head and superolateral central cartilage lesions compared with the FAI group. There was no statistical difference between high-grade femoral or acetabular cartilage lesions between groups. CONCLUSIONS: Patients with SCFE were younger at the time of surgery and presented with more severe deformity based on radiographic α-angle compared to patients with FAI. Our results suggest higher prevalence of femoral head lesions and more diffuse cartilage injury in patients with SCFE. This study can be used to support early surgical intervention in patients with symptomatic sequelae of SCFE due to risk of premature joint damage. LEVEL OF EVIDENCE: Level III-prognostic study.

The characteristics of the whole pelvic morphology in slipped capital femoral epiphysis: A retrospective observational study.

Slipped capital femoral epiphysis (SCFE) is a very common disorder affecting the adolescent hip. The etiology of SCFE is multifactorial and mechanical force associated with the characteristic morphology of the hip is considered one of the causes of SCFE. We investigated the characteristics of whole pelvic morphology including pelvic incidence (PI) in patients with SCFE and compared it with pelvic morphology in healthy children. We retrospectively assessed the whole pelvic morphology of 17 patients with SCFE and 51 healthy children using their pelvic computed tomography data. We measured superior iliac angle, inferior iliac angle, and ischiopubic angle as the parameters of pelvic rotation. Additionally, we measured acetabular anteversion of the superior acetabulum (AVsup) and of the center of the acetabulum (AVcen), and measured anterior acetabular sector angle (AASA), posterior acetabular sector angle, and the superior acetabular sector angle (SASA) as parameters of acetabular coverage and PI. Each measurement was compared between the 2 groups. AASA and SASA of patients with SCFE were significantly greater than that of controls, and AVsup of patients with SCFE was significantly smaller. There were no significant differences in pelvic rotation, PI, or AVcen between the 2 groups. This is the 1st report to evaluate SCFE patients' whole pelvic morphology including PI and pelvic rotation. Our results showed that patients with SCFE have excessive coverage of the anterior and superior acetabulum, and a more retroverted cranial acetabulum as compared with healthy control subjects. Such characteristic pelvic morphology may be involved in the onset of SCFE. To clarify the mechanical forces involved in SCFE onset, further investigations of pelvic morphology and alignment, including the femur and spine, are needed.

Smaller Epiphyseal Tubercle and Larger Peripheral Cupping in Slipped Capital Femoral Epiphysis Compared with Healthy Hips: A 3-Dimensional Computed Tomography Study.

BACKGROUND: The inner surface of the capital femoral epiphysis is important for growth plate stability. However, abnormalities of epiphyseal morphology associated with the pathogenesis of slipped capital femoral epiphysis (SCFE) remain poorly understood. This study compares the 3-dimensional anatomy of the epiphyseal tubercle and peripheral cupping in hips with SCFE and normal hips. METHODS: We created 3-dimensional models of the capital femoral epiphysis with use of computed tomography (CT) imaging from 51 patients with SCFE and 80 subjects without hip symptoms who underwent CT because of abdominal pain. The height, width, and length of the epiphyseal tubercle and the peripheral cupping were measured and normalized by the epiphyseal diameter and presented as a percentage. We used analysis of variance for the comparison of the measurements between SCFE and control hips after adjusting for age and sex. RESULTS: Compared with normal hips, hips with mild SCFE had smaller mean epiphyseal tubercle height (0.9% ± 0.9% compared with 4.4% ± 0.4%; p = 0.006) and length (32.3% ± 1.8% compared with 43.7% ± 0.8%; p < 0.001). The mean epiphyseal tubercle height was also smaller in hips with moderate (0.6% ± 0.9%; p = 0.004) and severe SCFE (0.3% ± 0.8%; p < 0.001) compared with normal hips. No differences were observed for measurements of epiphyseal tubercle height and length between SCFE subgroups. The mean peripheral cupping was larger in hips with mild (16.3% ± 1.0%; p < 0.001), moderate (16.4% ± 1.1%; p < 0.001), and severe SCFE (18.9% ± 0.9%; p < 0.001) overall and when assessed individually in all regions compared with normal hips (10.6% ± 0.5%). CONCLUSIONS: Hips with SCFE have a smaller epiphyseal tubercle and larger peripheral cupping compared with healthy hips. A smaller epiphyseal tubercle may be a predisposing morphologic factor or a consequence of the increased shearing stress across the physis secondary to the slip. Increased peripheral growth may be an adaptive response to instability as other stabilizers (i.e., epiphyseal tubercle and anterior periosteum) become compromised with slip progression. Future studies are necessary to determine the biomechanical basis of our morphologic findings.

Slipped capital femoral epiphysis in an adult with congenital hypopituitarism: A case report.

RATIONALE: Slipped capital femoral epiphysis (SCFE) is a common hip problem in adolescents, usually individuals between 8 and 15 years old. Because of the frequent finding of growth abnormalities in affected children, various endocrine disturbances have been reported as the cause of the disease. However, there are few case reports of older patients in previous literature. To the best of our knowledge, congenital hypopituitarism with normal growth hormone (GH) level has not been reported. PATIENT CONCERNS: We describe a 29-year-old man who had a 3-month history of pain in the left hip with tall stature and unobvious secondary sexual characteristics. Laboratory testing showed low thyroxine, low cortisol, low follicle-stimulating hormone, low luteinizing hormone, low testosterone, but normal GH. DIAGNOSES: Brain magnetic resonance imaging showed pituitary hypoplasia. An anteroposterior pelvis radiograph showed severe varus SCFE in the left hip, it was also confirmed with computed tomography scans. INTERVENTIONS: The patient was treated with levothyroxine, hydrocortisone, and testosterone replacement therapy before surgery. We performed open reduction and anatomical reduction by Dunn's procedure. OUTCOME: We have followed this patient for 6 months, the left hip mobility gradually improved. No slip in the contralateral proximal femoral physis has been observed. LESSONS: When unobvious secondary sexual characteristics and body abnormalities were found in clinical practice, endocrine condition should be evaluated, since the contralateral side may prone to slip due to the lack of endocrine therapy.

The Peritubercle Lucency Sign is a Common and Early Radiographic Finding in Slipped Capital Femoral Epiphysis.

BACKGROUND: A rotational mechanism of slipped capital femoral epiphysis (SCFE) in which the epiphyseal tubercle acts as a fulcrum has been recently described. However, there is limited radiographic evidence supporting this theory. We aimed to investigate whether a radiographic lucency around the epiphyseal tubercle (peritubercle lucency sign) could be observed before or at the diagnosis of a subsequent slip in patients initially presenting with unilateral SCFE. METHODS: We evaluated 70 patients with unilateral SCFE who were followed until a contralateral slip was diagnosed, and 180 patients with unilateral SCFE who had no contralateral slip until skeletal maturity between 2000 and 2017. We revised anteroposterior and lateral radiographs from the initial presentation, surveillance, and diagnosis of a contralateral SCFE. The presence or absence of the peritubercle lucency sign in the contralateral initially uninvolved hip was recorded for every radiograph. The presence of hip pain, and the presence of classic radiographic parameters for SCFE diagnosis (epiphyseal tilt and Klein's line) were recorded when the peritubercle lucency sign became noticeable. RESULTS: The peritubercle lucency sign was observed in 84% [59/70; 95% confidence interval (CI), 73%-92%] of the patients who developed contralateral slip. Most patients (46/59=78%; 95% CI, 65%-87%; P<0.001) had the peritubercle lucency sign visible within 9 months after the initial diagnosis of unilateral SCFE. The sign preceded the definitive diagnosis of the contralateral slip at a median of 9 weeks (interquartile range, 0 to 10 wk). At the time of first observation of the peritubercle lucency sign, 36% (25/70; 95% CI, 25%-48%) of the patients were asymptomatic and 49% (34/70; 95% CI, 36%-61%) of the hips showed no abnormalities in the tilt angle or the Klein line. Among patients who did not experience a contralateral slip (n=180), the sign was observed in 2 patients (1.1%; 95% CI, 0.2%-4.4%). The sensitivity was 84% and specificity was 99%. CONCLUSIONS: A peritubercle lucency is an early imaging sign, present in >80% of contralateral slips following an initial presentation of unilateral SCFE. The presence of the peritubercle lucency sign may be helpful for contralateral hip surveillance. Future studies are necessary to establish the clinical validity of the peritubercle lucency sign and whether it may serve as a predictor of contralateral involvement. LEVEL OF EVIDENCE: Diagnostic level III.

Incremental Value of SPECT/CT in the Detection of Femoral Head Viability in Slipped Capital Femoral Epiphysis.

In this article, we discuss the role of 99mTc-methylene diphosphonate SPECT/CT in 2 cases of slipped capital femoral epiphysis. We describe the incremental value of SPECT/CT in determining the viability of the femoral head and the implications in management of patients with slipped epiphysis.

Pseudohypoparathyroidism type 1B in a patient conceived by in vitro fertilization: another imprinting disorder reported with assisted reproductive technology.

Pseudohypoparathyroidism type 1B (PHP1B) is characterized by renal tubular resistance to parathyroid hormone (PTH) leading to hyperphosphatemia, hypocalcemia, elevated PTH, and hyperparathyroid bone changes. PHP1B is an imprinting disorder that results from loss of methylation at the maternal GNAS gene, which suppresses transcription of the alpha subunit of the stimulatory G protein of the PTH receptor. Emerging evidence supports an association between assisted reproductive technologies (ART) and imprinting disorders; however, there is currently little evidence linking PHP1B and ART. We present a twin boy conceived by ART to parents with no history of subfertility who presented at age 12 with bilateral slipped capital femoral epiphysis and bilateral genu valgum deformity. Clinical and laboratory investigation revealed markedly elevated PTH, low ionized calcium, elevated phosphorus, TSH resistance, and skeletal evidence of hyperparathyroidism, leading to the diagnosis of PHP1B. A partial loss of methylation at the GNAS exon A/B locus was observed. The patient's dizygotic twin sibling was asymptomatic and had normal laboratory evaluation. This is the second reported case of a child with PHP1B conceived by ART, further supporting the possibility that ART may lead to an increased risk for imprinting defects.

Diagnosis and treatment of slipped capital femoral epiphysis: Recent trends to note.

Slipped capital femoral epiphysis (SCFE) is not frequently encountered during routine practice and diagnosis and treatment are often delayed. It is important to understand symptoms and imaging features to avoid delayed diagnosis. After the diagnosis is made correct classification of the disease is required. The classification should be based on the physeal stability in order to choose safe and effective treatment. However, surgeons should bear in mind that the assessment is challenging and actual physeal stability is not always consistent with the stability predicted by a clinical classification method. TREATMENT OF STABLE SCFE: Closed reduction is not indicated for stable SCFE, where continuity between the epiphysis and metaphysis has not been disrupted. Treatment method(s) is (are) chosen from in-situ fixation, osteotomy and femoroacetabular impingement treatment. A single screw fixation is often used to fix the epiphysis and the dynamic method is considered especially for young patients. Traditional three-dimensional trochanteric osteotomies have been associated with procedural complexity and uncertainty. A simpler osteotomy method using an updated imaging analysis technology should be considered. Modified-Dunn procedure is indicated for a severe stable SCFE. However, caution is required because recent studies have reported a high rate of complications including postoperative femoral head avascular necrosis (AVN) and hip instability when this method is indicated for stable SCFE. TREATMENT OF UNSTABLE SCFE: Treatment of unstable SCFE is difficult and complication rate is high. Most of unstable SCFE patients were previously treated with closed method and it was difficult to predict an occurrence of postoperative AVN. However, treatment of unstable SCFE has gradually changed in recent years and many studies have shown that physeal hemodynamics can be assessed during treatment. Preoperative assessments include contrast-enhanced MRI and bone scintigraphy. Intraoperative assessments include confirmation of bleeding after drilling the femoral head and monitoring the intracranial pressure by laser doppler flowmetry. It is expected that postoperative AVN can be prevented in many cases by performing the treatment while assessing the intraoperative physeal hemodynamics. Open surgeries have begun to be indicated in the treatment of unstable SCFE through either of anterior approach or (modified) Dunn procedure. The authors expect that recent improvements in assessment of physeal hemodynamics and open treatment method provide improved clinical outcomes in the treatment of SCFE.

Treatment of Unstable Slipped Capital Epiphysis Via the Modified Dunn Procedure.

BACKGROUND: The modified Dunn procedure has been shown to be safe and effective in treating unstable slipped capital femoral epiphysis (SCFE). We present a consecutive series of unstable SCFE managed by a single surgeon with a focus on timing of surgical intervention, postoperative complications, and radiographic results. METHODS: Thirty-one consecutive unstable SCFEs were treated. Demographics, presentation time to time of operation, surgical times, and complications were recorded. Bilateral hip radiographs at latest follow-up were utilized to record slip angle, α angle, greater trochanteric height, and femoral neck length. RESULTS: Thirty-one consecutive hips in 30 patients were reviewed: 15 males (50%) and 15 females (50%), average age 12.37 years (range, 8.75 to 14.8 y), 20 left hips (65%) and 11 right hips (35%). Mean follow-up was 27.9 months (range, 1 to 82 mo). Time from presentation to intervention averaged 13.9 hours (range, 2.17 to 23.4 h). Two patients (6%) developed avascular necrosis at average 19 weeks postoperative. Three patients (10%) developed mild heterotopic ossification requiring no treatment. Two patients (6%) required removal of symptomatic hardware. One patient had hardware failure and in no patients was nonunion, delayed union, or postoperative hip subluxation/dislocation seen. Three patients (10%) presented with bilateral, stable SCFE requiring contralateral in situ pinning. Five patients (16%) had sequential SCFE requiring treatment with 1 patient having an acute, unstable SCFE 10 months after the previous realignment. Mean postoperative slip angle measured 2.5 degrees (range, +19 to -9.4 degrees) (SD, 7.2), α angle 47.43 degrees (range, 34 to 64 degrees) (SD, 7.49), greater trochanteric height averaged 3.5 mm below the center of femoral head (-17.5 to +25 mm), and mean femoral neck length difference measured -7.75 mm (range, -1.8 to -18.6 mm). CONCLUSIONS: A single surgeon series of unstable SCFEs treated by a modified Dunn procedure showed a 6% incidence of avascular necrosis and low complication rates at latest follow-up. Radiographs showed restoration of the slip angle, α angle, femoral neck length, and greater trochanteric height. This series reveals the safety and effectiveness of the modified Dunn procedure for unstable SCFE. LEVEL OF EVIDENCE: Level III-retrospective review.

Musculoskeletal complications following total body irradiation in hematopoietic stem cell transplant patients.

Total body irradiation (TBI) is commonly used in conditioning regimens for allogeneic hematopoietic stem cell transplantation (HSCT) to treat benign and malignant disease. Though life-saving, these therapies place patients at risk for important side effects, including musculoskeletal complications such as short stature, osteonecrosis, slipped capital femoral epiphysis, and the development of benign and malignant bone tumors. With an increasing number of HSCT survivors, there is a growing need for awareness of the musculoskeletal complications of HSCT and TBI.

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.

Prepubertal onset of slipped capital femoral epiphysis associated with hypothyroidism: a case report and literature review.

BACKGROUND: Slipped capital femoral epiphysis (SCFE) is a common hip disorder characterized by displacement of the capital femoral epiphysis from the metaphysic through the femoral epiphyseal plate. SCFE usually occurs during puberty, with obesity a common risk factor. We experienced a rare case of SCFE associated with hypothyroidism in a prepubescent patient who was not obese. CASE PRESENTATION: The patient was an 8-year-old boy suffering from bilateral SCFE with hypothyroidism. The patient's growth had started to slow at 4 years of age, and at 8 years he was of short stature. During his evaluation for SCFE management, primary hypothyroidism was diagnosed due to the presence of anti-thyroid peroxidase and anti-thyroglobulin antibodies. After the patient was treated for hypothyroidism, which improved his thyroid function, surgery was performed for bilateral SCFE. CONCLUSIONS: Among the 42 patients with SCFE associated with hypothyroidism in the literature, most SCFE occurred during puberty or in adults with delayed epiphyseal closure. Only two patients (4.8%), including the present patient, were ≤9 years old. Although being overweight or obese is common for patients with SCFE associated with hypothyroidism (76.0%), it was not observed in the present case. Persistent hypothyroidism, however, may be a risk factor for SCFE even before puberty and without obesity.

Acetabular Retroversion, but Not Increased Acetabular Depth or Coverage, in Slipped Capital Femoral Epiphysis: A Matched-Cohort Study.

BACKGROUND: Femoral head overcoverage by a deep and retroverted acetabulum has been postulated as a mechanical factor in slipped capital femoral epiphysis (SCFE). We assessed acetabular depth, coverage, and version in the hips of patients with unilateral SCFE; in the contralateral, uninvolved hips; and in healthy control hips. METHODS: Thirty-six patients affected by unilateral SCFE were matched to 36 controls on the basis of sex and age. The acetabular depth-width ratio (ADR), the lateral center-edge angle (LCEA), the anterior and posterior acetabular sector angle (ASA), and version (10 mm distal to the highest point of the acetabular dome and at the level of the femoral head center) were assessed on computed tomography (CT). A repeated-measures analysis of variance was used to assess differences among the SCFE, contralateral, and matched-control hips. Pairwise comparisons were conducted using Bonferroni correction for multiple comparisons. RESULTS: The mean coronal ADR was significantly lower in the hips affected by SCFE (311.6) compared with the contralateral hips (336.1) (p = 0.001) but did not differ from that of controls (331.9) (p = 0.08). The mean LCEA was significantly lower in the SCFE hips (29.8°) compared with the contralateral hips (33.7°) (p < 0.001) but did not differ from that of controls (32.2°) (p = 0.25). The mean anterior ASA did not differ between the SCFE hips (65.0°) and the contralateral hips (66.0°) (p = 0.68) or the control hips (64.5°) (p = 1.00). The mean posterior ASA in the SCFE hips (92.5°) was significantly lower than that in the contralateral hips (96.5°) (p = 0.002), but no difference was observed between the SCFE hips and controls (96.0°) (p = 0.83). The acetabulum was retroverted cranially in the SCFE hips compared with the contralateral hips (2.7° versus 6.6°; p = 0.01) and compared with controls (2.7° versus 9.6°; p = 0.005). A lower mean value for acetabular version at the level of the femoral head center was also observed in the SCFE hips compared with the contralateral hips (13.9° versus 15.5°; p = 0.04) and compared with controls (13.9° versus 16.0°; p = 0.045). No significant difference (p > 0.05) in acetabular measurements was observed between the contralateral and control hips. CONCLUSIONS: In SCFE, the acetabulum has reduced version but is not deeper, nor is there acetabular overcoverage. Additional longitudinal studies will clarify whether acetabular retroversion is a primary abnormality influencing the mechanics of SCFE development or an adaptive response to the slip. Our data suggest that the contralateral, uninvolved hip in patients with unilateral SCFE has normal acetabular morphology. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Microarray analysis of slipped capital femoral epiphysis growth plates.

BACKGROUND: Microarray technology has been used to analyze gene expression in patients with and without slipped capital femoral epiphysis (SCFE). METHODS: Proximal femoral physis core biopsies from two patients with SCFE were compared with two control specimens from age-matched patients without SCFE. Extracted RNA from frozen ground samples was subjected to microarray analysis with data tests for statistical significance between SCFE and control tissues. RESULTS: Compared to controls, SCFE samples demonstrated significant up-regulation in gene expression pathways involving physiological defense and inflammatory responses and significant down-regulation in the regulation of cellular physiologic processes, cellular metabolic pathways, and skeletal development pathways including expression of aggrecan and type II collagen, genes affecting physeal structure and integrity. CONCLUSIONS: Up-regulation of inflammatory and immune response pathways in SCFE compared to controls relates to physeal mechanical displacement in SCFE. Globalized down-regulation of several other pathways suggests growth plate weakening. These novel microarray findings further define SCFE etiology.

Validity and Clinical Consequences of a Rotational Mechanism for Slipped Capital Femoral Epiphysis.

BACKGROUND: Recent anatomic data supports a mechanism for slipped capital femoral epiphysis (SCFE) where the metaphysis rotates on the epiphysis through the eccentrically located epiphyseal tubercle as a pivot. The validity of such a mechanism and its clinical consequences have not been well investigated. METHODS: This cadaveric study defined the normal location of the calcar ridge line in 100 paired femora and compared them with 11 SCFE specimens, and with 25 immature femora where the metaphysis was rotated 30, 60, and 90 degrees on the epiphysis to model progressive SCFE. Coronal, sagittal, and axial plane deformity were measured on the rotational model to define the characteristic deformity caused by rotation, and lateral epiphyseal foramina stretch was measured to quantify the protective effect of an eccentric pivot. RESULTS: The posterior displacement of the fovea with respect to the calcar ridge line was 1±5 mm for the controls, versus 23±10 mm for the SCFE specimens (P<0.0005), and posterior displacement increased with incremental rotation in the rotational model (P<0.0005). The rotational model found minimal varus deformity, but substantial extension and retroversion, with deformities of 0±5, -16±12, and -38±9 degrees, respectively, at 90 degrees of rotation. The eccentric pivot mitigated lateral epiphyseal vessel stretch by 55% to 70%. CONCLUSIONS: This study provides strong anatomic support for a rotational mechanism for stable SCFE. When the metaphysis is rotated on the epiphysis acutely, minimal varus deformity is created, while substantial retroversion occurs. As this rotation occurs the eccentric pivot protects the lateral epiphyseal vessels, and likely accounts for the low rate of avascular necrosis observed in stable SCFE. CLINICAL RELEVANCE: If SCFE is treated in an open manner then the presence of a chronic rotational deformity should be considered. When planning osteotomies for deformity after a stable SCFE, any suspected varus component should be carefully investigated as it may represent retroversion deformity brought into view by external rotation posturing of the leg.

Multi-scale finite element model of growth plate damage during the development of slipped capital femoral epiphysis.

Slipped capital femoral epiphysis (SCFE) is one of the most common disorders of adolescent hips. A number of works have related the development of SCFE to mechanical factors. Due to the difficulty of diagnosing SCFE in its early stages, the disorder often progresses over time, resulting in serious side effects. Therefore, the development of a tool to predict the initiation of damage in the growth plate is needed. Because the growth plate is a heterogeneous structure, to develop a precise and reliable model, it is necessary to consider this structure from both macro- and microscale perspectives. Thus, the main objective of this work is to develop a numerical multi-scale model that links damage occurring at the microscale to damage occurring at the macroscale. The use of this model enables us to predict which regions of the growth plate are at high risk of damage. First, we have independently analyzed the microscale to simulate the microstructure under shear and tensile tests to calibrate the damage model. Second, we have employed the model to simulate damage occurring in standardized healthy and affected femurs during the heel-strike stage of stair climbing. Our results indicate that on the macroscale, damage is concentrated in the medial region of the growth plate in both healthy and affected femurs. Furthermore, damage to the affected femur is greater than damage to the healthy femur from both the micro- and macrostandpoints. Maximal damage is observed in territorial matrices. Furthermore, simulations illustrate that little damage occurs in the reserve zone. These findings are consistent with previous findings reported in well-known experimental works.

Pelvic Incidence and Acetabular Version in Slipped Capital Femoral Epiphysis.

BACKGROUND: The etiology of slipped capital femoral epiphysis (SCFE) is multifactorial, but the role of sagittal balance of the pelvis as a contributing factor to its development has not been well studied. Our primary purpose was to determine whether a smaller pelvic incidence (PI), a position-independent anatomic parameter that regulates pelvic orientation, could be a factor that increases shear stress in the epiphyseal growth plate and potentially contributes to the development of SCFE. We also set out to determine whether acetabular retroversion was associated with SCFE. METHODS: We obtained 14 cadaveric pelvi from the Hamann-Todd Osteological Collection whose femurs showed evidence of post-SCFE deformity. Two hundred age-matched, sex-matched, and race-matched pelvi were used as controls. PI and acetabular version were measured using standardized lateral photographs and goniometers, respectively. T tests were performed to evaluate for differences in measured parameters between groups. RESULTS: The mean PI was 40.6±6.1 degrees for SCFE specimens and 47.4±9.9 degrees for normal specimens (P=0.01). The mean version of SCFE and normal acetabula was 15±7 and 17±6 degrees, respectively (P=0.39). There was also no significant difference in version between SCFE acetabula and the contralateral, uninvolved acetabular of the same specimen (15±7 vs. 17±8 degrees, P=0.33). CONCLUSIONS: Specimens with SCFE deformity demonstrated a smaller PI than a large cohort of normal control specimens. We found no significant difference between acetabular version of specimens with and without SCFE deformity. Contralateral or unaffected acetabuli of SCFE specimens were not more retroverted than the affected side of the same specimen. CLINICAL RELEVANCE: Sagittal balance of the pelvis, and particularly decreased PI, may play an important role in the development of SCFE. The influence of mechanical factors beyond the hip joint in the development of SCFE should be considered by clinicians.