Investigating pelvic drop gait abnormality in adolescent hip pathology patients.

BACKGROUND: Trendelenburg gait describes contralateral pelvic drop during single leg stance (SLS) with occasional lateral trunk lean compensation over the stance limb. However, quantitative research on 'uncompensated Trendelenburg' gait (pelvic drop independent of lateral trunk lean) remains sparse among populations that commonly utilize this gait pattern, such as adolescent hip pathology patients. RESEARCH QUESTION: How prevalent is uncompensated Trendelenburg among various adolescent hip pathologies and how is it related to hip load, hip abduction strength, and self-reported hip pain? METHODS: Gait, strength, and pain data were collected among 152 pre-operative patients clinically diagnosed with acetabular hip dysplasia, femoroacetabular impingement, Legg-Calvé-Perthes, or slipped capital femoral epiphysis (SCFE). Patients with ≥ 5.4° of dynamic pelvic drop in SLS were divided into a 'pelvic drop' group and screened to exclude those with excessive ipsilateral trunk lean. They were then compared to the 'stable pelvis' patients using a Mann-Whitney test. RESULTS: Dysplasia patients represented the highest proportion of the pelvic drop group (46%). The pelvic drop group showed a significant increase in self-reported hip pain (p = 0.011), maximum hip abductor moment (p = 0.002), and peak coronal power absorption at the affected hip during SLS loading response, (p < 0.001) while showing no difference in abduction strength (p = 0.381). SIGNIFICANCE: Uncompensated Trendelenburg gait may lead to increased loading of the affected hip in adolescent hip pathology patients. Disadvantageous hip biomechanics can create increased abductor muscle demand among these pathological populations, with dysplasia patients showing the highest prevalence. Maximal abduction strength did not correlate with pelvic drop. Future work should aim to identify and quantify causal factors. Increased coronal hip power absorption during weight acceptance warrants clinical attention, as there may be a detrimental, over-reliance on passive hip structures to support load among a population that that is already predisposed to hip osteoarthritis.

PROMIS Paediatric Mobility tool is correlated with accelerometer-measured physical activity in children with hip diseases.

AIMS: The reduction in mobility due to hip diseases in children is likely to affect their physical activity (PA) levels. Physical inactivity negatively influences quality of life and health. Our aim was to objectively measure PA in children with hip disease, and correlate it with the Patient-Reported Outcomes Measurement Information System (PROMIS) Mobility Score. METHODS: A total of 28 children (12 boys and 16 girls) with hip disease aged between 8and 17 years (mean 12 (SD 3)) were studied between December 2018 and July 2019. Children completed the PROMIS Paediatric Item Bank v. 2.0 - Mobility Short Form 8a and wore a hip accelerometer (ActiGraph) for seven consecutive days. Sedentary time (ST), light PA (LPA), moderate to vigorous PA (MVPA), and vigorous PA were calculated from the accelerometers' data. The PROMIS Mobility score was classified as normal, mild, and moderate functions, based on the PROMIS cut scores on the physical function metric. A one-way analysis of covariance (ANCOVA) was used to assess differences among mobility (normal; mild; moderate) and measured PA and relationships between these variables were assessed using bivariate Pearson correlations. RESULTS: Children classified as normally functioning on the PROMIS had less ST (p = 0.002), higher MVPA, (p = 0.002) and VPA (p = 0.004) compared to those classified as mild or moderate function. A moderate correlation was evident between the overall PROMIS score and daily LPA (r = 0.462, n = 28; p = 0.013), moderate-to-vigorous PA (r = 0.689, n = 28; p = 0.013) and vigorous PA (VPA) (r = 0.535, n = 28; p = 0.013). No correlation was evident between the mean daily ST and overall PROMIS score (r = -0.282, n = 28; p = 0.146). CONCLUSION: PROMIS Pediatric Mobility tool correlates well with experimentally measured levels of physical activity in children with hip disease. We provide external validity for the use of this tool as a measure of physical activity in children. Cite this article: Bone Joint J 2021;103-B(2):405-410.

Epiphyseal Translation as a Predictor of Avascular Necrosis in Unstable Slipped Capital Femoral Epiphysis.

BACKGROUND: Physeal instability has been shown to be associated with a higher risk of avascular necrosis (AVN) in patients with slipped capital femoral epiphysis (SCFE). The purpose of this study was to identify additional preoperative factors associated with AVN in patients with unstable SCFE. METHODS: Basic demographic information, chronicity of symptoms, and estimated duration of nonambulatory status were noted. Preoperative radiographs were used to measure the Southwick slip angle, slip severity by Wilson criteria, and epiphyseal translation. Translation was measured by 3 distinct radiographic parameters in the position demonstrating maximal displacement. Postoperative radiographs at the time of most recent follow-up were assessed for the presence of AVN. Translation measurements were tested for inter-rater reliability. Patients who developed AVN were compared with those that did not by Fisher exact test and Wilcoxon tests. Logistic regression assessed the effect of translation on the odds of developing AVN. Receiver operating characteristic curve was plotted to assess any threshold effect. RESULTS: Fifty-one patients (55 hips) out of 310 patients (16%) treated for SCFE were considered unstable. Seventeen hips' unstable SCFE (31%) showed radiographic evidence of AVN. Slip severity by Wilson grade (P=0.009) and epiphyseal translation by all measurements (P< 0.05) were statistically significantly greater among patients who developed AVN. Superior translation had the best inter-rater reliability (intraclass correlation coefficient=0.84). Average superior translation in hips that developed AVN was 17.2 mm compared with 12.9 mm in those that did not (P<0.02). Although the receiver operating characteristic curve did not demonstrate a threshold effect for AVN, it did effectively rule out AVN in cases with <1 cm of superior translation. Age, sex, laterality, chronicity of prodromal symptoms or inability to bear weight, Southwick slip angle, and method of treatment did not vary with the occurrence of AVN. CONCLUSIONS: Epiphyseal translation, either by Wilson Grade or measured directly, is associated with AVN in patients with an unstable SCFE. LEVEL OF EVIDENCE: Level II-development of diagnostic criteria.

How Common Is Femoral Retroversion and How Is it Affected by Different Measurement Methods in Unilateral Slipped Capital Femoral Epiphysis?

BACKGROUND: Although femoral retroversion has been linked to the onset of slipped capital femoral epiphysis (SCFE), and may result from a rotation of the femoral epiphysis around the epiphyseal tubercle leading to femoral retroversion, femoral version has rarely been described in patients with SCFE. Furthermore, the prevalence of actual femoral retroversion and the effect of different measurement methods on femoral version angles has yet to be studied in SCFE. QUESTIONS/PURPOSES: (1) Do femoral version and the prevalence of femoral retroversion differ between hips with SCFE and the asymptomatic contralateral side? (2) How do the mean femoral version angles and the prevalence of femoral retroversion change depending on the measurement method used? (3) What is the interobserver reliability and intraobserver reproducibility of these measurement methods? METHODS: For this retrospective, controlled, single-center study, we reviewed our institutional database for patients who were treated for unilateral SCFE and who had undergone a pelvic CT scan. During the period in question, the general indication for obtaining a CT scan was to define the surgical strategy based on the assessment of deformity severity in patients with newly diagnosed SCFE or with previous in situ fixation. After applying prespecified inclusion and exclusion criteria, we included 79 patients. The mean age was 15 ± 4 years, 48% (38 of 79) of the patients were male, and 56% (44 of 79) were obese (defined as a BMI > 95th percentile (mean BMI 34 ± 9 kg/m2). One radiology resident (6 years of experience) measured femoral version of the entire study group using five different methods. Femoral neck version was measured as the orientation of the femoral neck. Further measurement methods included the femoral head's center and differed regarding the level of landmarks for the proximal femoral reference axis. From proximal to distal, this included the most-proximal methods (Lee et al. and Reikerås et al.) and most-distal methods (Tomczak et al. and Murphy et al.). Most proximally (Lee et al. method), we used the most cephalic junction of the greater trochanter as the landmark and, most distally, we used the center base of the femoral neck superior to the lesser trochanter (Murphy et al.). The orientation of the distal femoral condyles served as the distal reference axis for all five measurement methods. All five methods were compared side-by-side (involved versus uninvolved hip), and comparisons among all five methods were performed using paired t-tests. The prevalence of femoral retroversion (< 0°) was compared using a chi-square test. A subset of patients was measured twice by the first observer and by a second orthopaedic resident (2 years of experience) to assess intraobserver reproducibility and interobserver reliability; for this assessment, we used intraclass correlation coefficients. RESULTS: The mean femoral neck version was lower in hips with SCFE than in the contralateral side (-2° ± 13° versus 7° ± 11°; p < 0.001). This yielded a mean side-by side difference of -8° ± 11° (95% CI -11° to -6°; p < 0.001) and a higher prevalence of femoral retroversion in hips with SCFE (58% [95% CI 47% to 69%]; p < 0.001) than on the contralateral side (29% [95% CI 19% to 39%]). These differences between hips with SCFE and the contralateral side were higher and ranged from -17° ± 11° (95% CI -20° to -15°; p < 0.001) based on the method of Tomczak et al. to -22° ± 13° (95% CI -25° to -19°; p < 0.001) according to the method of Murphy et al. The mean overall femoral version angles increased for hips with SCFE using more-distal landmarks compared with more-proximal landmarks. The prevalence of femoral retroversion was higher in hips with SCFE for the proximal methods of Lee et al. and Reikerås et al. (91% [95% CI 85% to 97%] and 84% [95% CI 76% to 92%], respectively) than for the distal measurement methods of Tomczak et al. and Murphy et al. (47% [95% CI 36% to 58%] and 60% [95% CI 49% to 71%], respectively [all p < 0.001]). We detected mean differences ranging from -19° to 4° (all p < 0.005) for 8 of 10 pairwise comparisons in hips with SCFE. Among these, the greatest differences were between the most-proximal methods and the more-distal methods, with a mean difference of -19° ± 7° (95% CI -21° to -18°; p < 0.001), comparing the methods of Lee et al. and Tomczak et al. In hips with SCFE, we found excellent agreement (intraclass correlation coefficient [ICC] > 0.80) for intraobserver reproducibility (reader 1, ICC 0.93 to 0.96) and interobserver reliability (ICC 0.95 to 0.98) for all five measurement methods. Analogously, we found excellent agreement (ICC > 0.80) for intraobserver reproducibility (reader 1, range 0.91 to 0.96) and interobserver reliability (range 0.89 to 0.98) for all five measurement methods in healthy contralateral hips. CONCLUSION: We showed that femoral neck version is asymmetrically decreased in unilateral SCFE, and that differences increase when including the femoral head's center. Thus, to assess the full extent of an SCFE deformity, femoral version measurements should consider the position of the displaced epiphysis. The prevalence of femoral retroversion was high in patients with SCFE and increased when using proximal anatomic landmarks. Since the range of femoral version angles was wide, femoral version cannot be predicted in a given hip and must be assessed individually. Based on these findings, we believe it is worthwhile to add evaluation of femoral version to the diagnostic workup of children with SCFE. Doing so may better inform surgeons as they contemplate when to use isolated offset correction or to perform an additional femoral osteotomy for SCFE correction based on the severity of the slip and the rotational deformity. To facilitate communication among physicians and for the design of future studies, we recommend consistently reporting the applied measurement technique. LEVEL OF EVIDENCE: Level III, prognostic study.

What Is the Association Among Epiphyseal Rotation, Translation, and the Morphology of the Epiphysis and Metaphysis in Slipped Capital Femoral Epiphysis?

BACKGROUND: Contemporary studies have described the rotational mechanism in patients with slipped capital femoral epiphysis (SCFE). However, there have been limited patient imaging data and information to quantify the rotation. Determining whether the epiphysis is rotated or translated and measuring the epiphyseal displacement in all planes may facilitate planning for surgical reorientation of the epiphysis. QUESTIONS/PURPOSES: (1) How does epiphyseal rotation and translation differ among mild, moderate, and severe SCFE? (2) Is there a correlation between epiphyseal rotation and posterior or inferior translation in hips with SCFE? (3) Does epiphyseal rotation correlate with the size of the epiphyseal tubercle or the metaphyseal fossa or with epiphyseal cupping? METHODS: We identified 51 patients (55% boys [28 of 51]; mean age 13 ± 2 years) with stable SCFE who underwent preoperative CT of the pelvis before definitive treatment. Stable SCFE was selected because unstable SCFE would not allow for accurate assessment of rotation given the complete displacement of the femoral head in relation to the neck. The epiphysis and metaphysis were segmented and reconstructed in three-dimensions (3-D) for analysis in this retrospective study. One observer (a second-year orthopaedic resident) performed the image segmentation and measurements of epiphyseal rotation and translation relative to the metaphysis, epiphyseal tubercle, metaphyseal fossa, and the epiphysis extension onto the metaphysis defined as epiphyseal cupping. To assess the reliability of the measurements, a randomly selected subset of 15 hips was remeasured by the primary examiner and by the two experienced examiners independently. We used ANOVA to calculate the intraclass and interclass correlation coefficients (ICCs) for intraobserver and interobserver reliability of rotational and translational measurements. The ICC values for rotation were 0.91 (intraobserver) and 0.87 (interobserver) and the ICC values for translation were 0.92 (intraobserver) and 0.87 (intraobserver). After adjusting for age and sex, we compared the degree of rotation and translation among mild, moderate, and severe SCFE. Pearson correlation analysis was used to assess the associations between rotation and translation and between rotation and tubercle, fossa, and cupping measurements. RESULTS: Hips with severe SCFE had greater epiphyseal rotation than hips with mild SCFE (adjusted mean difference 21° [95% CI 11° to 31°]; p < 0.001) and hips with moderate SCFE (adjusted mean difference 13° [95% CI 3° to 23°]; p = 0.007). Epiphyseal rotation was positively correlated with posterior translation (r = 0.33 [95% CI 0.06 to 0.55]; p = 0.02) but not with inferior translation (r = 0.16 [95% CI -0.12 to 0.41]; p = 0.27). There was a positive correlation between rotation and metaphyseal fossa depth (r = 0.35 [95% CI 0.08 to 0.57]; p = 0.01), width (r = 0.41 [95% CI 0.15 to 0.61]; p = 0.003), and length (r = 0.56 [95% CI 0.38 to 0.75]; p < 0.001). CONCLUSION: This study supports a rotational mechanism for the pathogenesis of SCFE. Increased rotation is associated with more severe slips, posterior epiphyseal translation, and enlargement of the metaphyseal fossa. The rotational nature of the deformity, with the center of rotation at the epiphyseal tubercle, should be considered when planning in situ fixation and realignment surgery. Avoiding placing a screw through the epiphyseal tubercle-the pivot point of rotation- may increase the stability of the epiphysis. The realignment of the epiphysis through rotation rather than simple translation is recommended during the open subcapital realignment procedure. Enlargement of the metaphyseal fossa disrupts the interlocking mechanism with the tubercle and increases epiphyseal instability. Even in the setting of a stable SCFE, an increased fossa enlargement may indicate using two screws instead of one screw, given the severity of epiphyseal rotation and the risk of instability. Further biomechanical studies should investigate the number and position of in situ fixation screws in relation to the epiphyseal tubercle and metaphyseal fossa. LEVEL OF EVIDENCE: Level III, prognostic study.

Does a History of Slipped Capital Femoral Epiphysis in Patients Undergoing Femoroacetabular Osteoplasty for Femoroacetabular Impingement Affect Outcomes Scores or Risk of Reoperation?

BACKGROUND: Femoroacetabular impingement (FAI) can occur after slipped capital femoral epiphysis (SCFE) regardless of slip severity and even after in situ pinning. These patients represent a rare and unique demographic that is largely unreported on. It is important to further characterize the clinical presentation of these patients, associated treatment modalities, and the efficacy of these treatment modalities. QUESTIONS/PURPOSES: (1) How do patients with post-SCFE FAI typically present in terms of radiographic and surgical findings? (2) How do their hip-specific and general-health outcomes scores after mini-open femoroacetabular osteoplasty compare with those obtained in a matched group of patients with FAI caused by other etiologies? (3) How do those groups compare in terms of the proportion who undergo conversion to THA? METHODS: Between 2013 and 2017, 20 patients had femoroacetabular osteoplasty for post-SCFE FAI. During that time, general indications for this procedure were symptomatic FAI demonstrated on radiographs and physical exam. Of those, none was lost to follow-up before a minimum of 2 years, leaving all 20 available for matching, and all 20 had suitable matches in our database for patients who underwent femoroacetabular osteoplasty for other diagnoses. Matching was performed by surgeon, patient age, patient gender, and BMI. The matching group was drawn from a large database of patients who had the same procedure during the same period. We matched in a 1:3 ratio to arrive at 60 randomly selected control patients in this retrospective, comparative study. Patient demographics, medical history, clinical presentation, radiographic parameters, and intraoperative findings were compared between the two groups. At a minimum of 2 years of follow-up, the latest clinical functional outcome scores (Hip Disability and Osteoarthritis Outcome Score Jr and SF-12) and proportions of conversion to THA were compared between the groups. RESULTS: A greater percentage of patients with a history of SCFE than those without prior SCFE demonstrated full chondral lesions intraoperatively (90% [18 of 20] versus 32% [19 of 60], odds ratio 7 [95% confidence interval 1 to 178]; p < 0.01). A greater percentage of patients with a history of SCFE also demonstrated labral calcifications intraoperatively compared with those without prior SCFE (65% [13 of 20] versus 35% [21 of 60], OR 3 [95% CI 1 to 10]; p = 0.04). Radiographically, patients with SCFE had greater preoperative alpha angles than did patients without SCFE (94° ± 13° versus 72° ± 22°; p = 0.01) as well as lower lateral center-edge angles (25° ± 8° versus 31° ± 8°; p = 0.04). There was no difference in postoperative follow-up between patients with a history of SCFE and patients without a history of SCFE (4 ± 2 years versus 4 ± 2 years; p = 0.32). There was no difference in the mean postoperative outcome scores between patients with a history of SCFE and patients without (Hip Disability and Osteoarthritis Outcome Score Jr: 75 ± 28 points versus 74 ± 17 points; p = 0.95; SF-12 physical score: 40 ± 11 points versus 39 ± 8 points; p = 0.79). There was no difference with the numbers available in the percentage of patients who underwent conversion to THA (15% [3 of 20] versus 12% [7 of 60], OR 1.36 [95% CI 0 to 6]; p = 0.71). CONCLUSION: Patients with FAI after SCFE present with a greater degree of labral and chondral disease than do patients without a history of SCFE. However, at short-term follow-up, the proportion of patients who underwent conversion to THA and patients' postoperative outcome scores did not differ in this small, comparative series between patients with and without SCFE. Further evaluation with long-term follow-up is needed, especially given the more severe chondral damage we observed in patients with SCFE at the time of surgery. LEVEL OF EVIDENCE: Level III, therapeutic study.

Clinical and radiological outcomes of chronic severe slipped capital femoral epiphysis patients treated by surgical dislocation and modified Dunn osteotomy: Case series.

OBJECTIVES: This study aims to evaluate the clinical and radiological outcomes of patients with chronic severe slipped capital femoral epiphysis (SCFE) treated by surgical dislocation and modified Dunn osteotomy (MDO). PATIENTS AND METHODS: This retrospective study, conducted between January 2010 and December 2017, included nine patients (8 males, 1 female; mean age 12.6 years; range, 7 to 16 years) with nine hips. The degree of corrections in Southwick angle and alpha angle were measured on frog-leg views. Range of motion (ROM) of the hips was measured at each follow-up visit. Heyman and Herndon classification system and Harris Hip Score (HHS) were evaluated for clinical and functional outcomes at the latest follow-up visit. RESULTS: The mean follow-up time was 34.8 months. Avascular necrosis complication was observed in one hip. Except two patients with lateral femoral cutaneous neuropathy, none of the patients suffered from any other complications. Mean preoperative Southwick angle of 59.1° was corrected to an angle of -0.8° postoperatively. Alpha angles were calculated as 44.6° postoperatively. Modified Dunn osteotomy resulted in marked improvement in hip ROM in all directions and increased HHS. CONCLUSION: Our results encourage us to use this method in treating SCFE patients with chronic severe slips.

The Role of Hyperinsulinemia in Slipped Capital Femoral Epiphysis.

BACKGROUND: Obesity in the prepuberal stage has been directly associated with slipped capital femoral epiphysis (SCFE). Serum insulin level increases in the prepuberal and adolescence stage, to a greater extent in the obese population. The main objective of this article was to analyze the relationship between insulin levels and SCFE. METHODS: A case-control study was conducted between January 2018 and April 2019. The study group was formed with patients with SCFE and the control group with patients from the pediatric obesity clinic of our hospital selected during their initial evaluation. None were being treated for obesity. Anthropometric measurements of size, weight, waist circumference, and blood pressure were taken. Body mass index (BMI) and waist-height index of all patients were calculated. According to BMI for age, they were classified as normal, overweight, or obese. Serum determinations of glucose, insulin, glycated hemoglobin, lipid profile, and complete blood count were analyzed. Insulin resistance was diagnosed with Homeostatic Model Assessment (HOMA) >3. Insulin levels >13 U/mL for girls and >17 U/mL for boys were considered as hyperinsulinemia. RESULTS: We studied 14 patients with SCFE and 23 in the control group. The mean age and BMI in both groups were similar. The elevation of serum insulin was significantly higher in the SCFE group (P=0.001) as was HOMA (P=0.005). Triglycerides and very-low-density lipoprotein were higher in the SCFE group (P=0.037 and 0.009, respectively). Glycemia, glycated hemoglobin, total cholesterol, high-density lipoprotein, low-density lipoprotein, and neutrophils showed no significant difference. CONCLUSIONS: Patients with SCFE showed elevated levels of insulin, HOMA, triglycerides, and very-low-density lipoprotein, even higher than the control group. Our study demonstrates a significant association between abnormally high serum insulin levels and SCFE. The known effects of insulin on growth cartilage may explain the physeal mechanical insufficiency to support the abnormally high or repetitive loads in accelerated growth stages that lead to SCFE. LEVEL OF EVIDENCE: Level III-case-control, prognostic study.

Capital Femoral Epiphyseal Cupping and Extension May Be Protective in Slipped Capital Femoral Epiphysis: A Dual-center Matching Cohort Study.

BACKGROUND: Peripheral cupping of the capital femoral epiphysis over the metaphysis has been reported as a precursor of cam morphology, but may also confer stability of the epiphysis protecting it from slipped capital femoral epiphysis (SCFE). The purpose of this study was to investigate the relationship between a novel morphologic parameter of inherent physeal stability, epiphyseal cupping, and the development of SCFE in a dual-center matched-control cohort study. METHODS: We performed a dual-center age-matched and sex-matched cohort study comparing 279 subjects with unilateral SCFE and 279 radiographically normal controls from 2 tertiary children's hospitals. All SCFE patients had at least 18 months of radiographic follow-up for contralateral slip surveillance. Anteroposterior and frog lateral pelvis radiographs were utilized to measure the epiphyseal cupping ratio and the current standard measure of inherent physeal stability, the epiphyseal extension ratio. RESULTS: Control hips were found to have greater epiphyseal cupping than the contralateral uninvolved hip of SCFE subjects both superiorly (0.28±0.08 vs. 0.24±0.06; P<0.001) and anteriorly (0.22±0.07 vs. 0.19±0.06; P<0.001). The 58/279 (21%) subjects who went on to develop contralateral slip had decreased epiphyseal cupping superiorly (0.25±0.07 vs. 0.23±0.05; P=0.03) and anteriorly (0.20±0.06 vs. 0.17±0.04; P<0.001). When we compared controls with hips that did not progress to contralateral slip and hips that further developed a contralateral SCFE, 1-way ANOVA demonstrated a stepwise decrease in epiphyseal cupping and epiphyseal extension ratio in the anterior and superior planes from control hips to contralateral hips without subsequent slip to contralateral hips that developed a SCFE (P<0.01 for each). CONCLUSIONS: This study provides further evidence that epiphyseal cupping around the metaphysis is associated with decreased likelihood of SCFE and may reflect increased inherent physeal stability. Epiphyseal cupping may represent an adaptive mechanism to stabilize the epiphysis during adolescence at the long-term cost of the eventual development of associated cam-femoroacetabular impingement deformity. LEVELS OF EVIDENCE: Level III-prognostic Study.

Evaluation of the Three-Dimensional Translational and Angular Deformity in Slipped Capital Femoral Epiphysis.

The purpose of this study was to quantify three-dimensional translational and angular deformity (defined as theta) present at the proximal femoral physis in slipped capital femoral epiphysis (SCFE), and to use theta to differentiate between SCFE hips, contralateral unaffected hips, and normal hips by comparing to the current gold standard measure of the Southwick slip angle (SSA). 3DCT reconstructions of the pelvis and femur in SCFE patients and normal adolescents were obtained and pelvic position was standardized. The center point and direction vector of the femoral epiphysis was determined. The femoral neck axis was defined. The angle between the femoral neck axis and epiphysis vector defined the 3D angle of deformity (theta). The 3D translation of the femoral epiphysis, measured as a percentage of femoral neck diameter, was measured in three planes. The average theta angle was significantly greater in SCFE hips (46.5 ± 24.3°) compared with control (13.7 ± 6.4°) or normal (11.7 ± 3.7°) hips (p < 0.001). There was no significant difference in theta angle between control and normal hips (p = 0.468). Theta angle correlated strongly with SSA (rs = 0.737, p < 0.001). Statement of clinical significance: The proximal femoral deformity in patients with slipped capital femoral epiphysis can be defined by measuring displacement of the epiphysis in all three dimensions in relation to the femoral neck axis. This information can be used in epiphyseal reorientation surgery to ensure anatomic reduction. The similarity between control and normal hips may argue against the thought that there is pre-existing deformity in a pre-slip condition of unaffected contralateral hips in SCFE patients. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:1081-1088, 2020.

Alpha Angle as a Predictor of Impending Contralateral Slipped Capital Femoral Epiphysis in an Asian Population.

BACKGROUND: Prophylactic pinning of the uninvolved side after unilateral slipped capital femoral epiphysis (SCFE) is controversial. The alpha angle, a measurement of femoral head-neck aspherity, was proposed as a predictor of progression of contralateral SCFE with a treatment threshold of greater than 50.5°. The aim of this study was to evaluate its validity in our cohort of patients. METHODS: A retrospective review of a 10-year series of patients who presented with unilateral SCFE was conducted. Minimum follow-up duration to identify contralateral progression was 18 months. Age, sex, ethnicity, and endocrinopathies were noted. Alpha angle measurements of the unaffected hip were performed by two independent observers. The average values of measurements were used for analysis. Univariate and multivariate logistic regression analyses were performed to identify predictors of contralateral progression. A receiver operating characteristic (ROC) curve was generated. RESULTS: There were 43 patients with unilateral SCFE. Seven patients (16.3%) developed contralateral SCFE. There were 31 males (72.1%) and 12 females (27.9%). The mean duration from index surgery to contralateral fixation was 43.9 weeks (range, 16.2 to 77 weeks). The mean alpha angle was significantly higher in the patients with contralateral progression (mean, 50.7°; standard deviation [SD], 5.4°; range, 43.8° to 58.5°) than in the patients without progression (mean, 43.0°; SD, 4.2°; range, 33.0° to 52.5°; p < 0.001). The alpha angle was also identified as a statistically significant predictor of contralateral progression on multivariate analysis (p = 0.02). The intraclass correlation coefficient for interobserver reliability was moderately strong at 0.76 (95% confidence interval, 0.55 to 0.87). The area under the ROC curve was 0.88. The treatment threshold of 50.5° had a sensitivity of 0.43, specificity of 0.94, and number needed to treat (NNT) of 2.7. The ideal treatment threshold derived from the ROC curve was 49.0°, which had a sensitivity of 0.71, specificity of 0.89, and an NNT of 1.7. CONCLUSIONS: Alpha angle is a potential predictor of contralateral hip involvement in children with SCFE who may benefit from prophylactic hip fixation. Results from our series suggest a treatment threshold be 49.0°. However, given the limited sample size and moderately strong interobserver reliability, larger studies are needed to validate our findings.

Treatment of Unstable Versus Stable Slipped Capital Femoral Epiphysis Using the Modified Dunn Procedure.

BACKGROUND: The modified Dunn procedure (open subcapital realignment via a surgical dislocation approach) has been shown to be a safe and effective way of treating acute, unstable slipped capital femoral epiphysis (SCFE). There is a paucity of literature comparing the modified Dunn procedure in stable SCFE. The purpose of this study was to compare acute, unstable versus chronic, stable SCFE managed with the modified Dunn procedure. METHODS: A retrospective chart review was performed on 44 skeletally immature patients who underwent the modified Dunn procedure for SCFE. Patients were divided into stable or unstable based on clinical presentation and intraoperative findings. Demographics, radiographic measurements, and complications were recorded and compared. χ and t tests were used to compare variables. RESULTS: In total, 31 consecutive hips (29 patients) with acute, unstable slips, and 17 consecutive hips (15 patients) with chronic, stable slips were reviewed. Average age was 12.5 and 13.8 years for acute and chronic, respectively (P=0.05). Mean follow-up was 27.9 months (unstable) and 35.5 months (stable). Average postoperative Southwick angle was 14.2 degrees; (unstable) and 25.3 degrees (stable) (P=0.001). Greater trochanteric height averaged 6.2 mm below the center of the femoral head in the acute group and 6.2 mm above center in the chronic group (P<0.001). Average femoral neck length measured 34.1 mm (unstable) and 27.1 mm (stable) (P<0.001). Two patients (6%) developed avascular necrosis (AVN) in the unstable group, with 5 patients (29.4%) in the stable group (P=0.027). All patients with hip instability (N=3) developed AVN. CONCLUSIONS: Although both acute, unstable and chronic, stable SCFE can be successfully treated with the modified Dunn procedure, the complication rate is statistically higher in patients with stable SCFE, specifically both AVN rate and postoperative instability. In addition, it is more difficult to establish normal anatomic indexes with regard to greater trochanteric height and femoral neck length. This procedure has great utility in the correction of the anatomic deformity associated with SCFE, but should be used with caution in patients with chronic, stable SCFE. LEVEL OF EVIDENCE: Level III-retrospective review.

Slipped Capital Femoral Epiphysis Presenting as Quadriceps Strain.

An active 14-year-old adolescent boy with left hip pain of 3 weeks in duration was referred for physical therapy consultation by his pediatrician, with a diagnosis of left quadriceps strain. Based on the findings during examination, the physical therapist immediately contacted the pediatrician to request radiographs, which confirmed a diagnosis of slipped capital femoral epiphysis. J Orthop Sports Phys Ther 2019;49(5):356. doi:10.2519/jospt.2019.8772.

Patients with severe slipped capital femoral epiphysis treated by the modified Dunn procedure have low rates of avascular necrosis, good outcomes, and little osteoarthritis at long-term follow-up.

AIMS: The modified Dunn procedure has the potential to restore the anatomy in hips with severe slipped capital femoral epiphyses (SCFE). However, there is a risk of developing avascular necrosis of the femoral head (AVN). In this paper, we report on clinical outcome, radiological outcome, AVN rate and complications, and the cumulative survivorship at long-term follow-up in patients undergoing the modified Dunn procedure for severe SCFE. PATIENTS AND METHODS: We performed a retrospective analysis involving 46 hips in 46 patients treated with a modified Dunn procedure for severe SCFE (slip angle > 60°) between 1999 and 2016. At nine-year-follow-up, 40 hips were available for clinical and radiological examination. Mean preoperative age was 13 years, and 14 hips (30%) presented with unstable slips. Mean preoperative slip angle was 64°. Kaplan-Meier survivorship was calculated. RESULTS: At the latest follow-up, the mean Merle d'Aubigné and Postel score was 17 points (14 to 18), mean modified Harris Hip Score was 94 points (66 to 100), and mean Hip Disability and Osteoarthritis Outcome Score was 91 points (67 to 100). Postoperative slip angle was 7° (1° to 16°). One hip (2%) had progression of osteoarthritis (OA). Two hips (5%) developed AVN of the femoral head and required further surgery. Three other hips (7%) underwent implant revision due to screw breakage or change of wires. Cumulative survivorship was 86% at ten-year follow-up. CONCLUSION: The modified Dunn procedure for severe SCFE resulted in a low rate of AVN, low risk of progression to OA, and high functional scores at long-term follow-up. The slip deformities were mainly corrected but secondary impingement deformities can develop in some hips and may require further surgical treatment. Cite this article: Bone Joint J 2019;101-B:403-414.

Capital Femoral Epiphyseal Extension May Confer Physeal Stability in Slipped Capital Femoral Epiphysis.

BACKGROUND: Factors including obesity and morphologic parameters around the hip that increase physeal stress are associated with an increased risk of slipped capital femoral epiphysis (SCFE). Recent evidence suggests that superior epiphyseal extension may confer stability to the physis and help protect against SCFE. The purpose of this study is to investigate the relationship between epiphyseal extension and SCFE using an age-matched and sex-matched cohort study. METHODS: We generated 2 separate cohorts for comparison: 89 patients with unilateral SCFE and 89 healthy subjects with no evidence of hip disease or deformity. We utilized the anterior-posterior and lateral films of the hip to measure the Southwick angle and the epiphyseal extension ratio (EER), defined as the ratio of extension of the capital femoral epiphysis down the femoral neck relative to the diameter of the femoral head. We then compared these measurements between cohorts and in subgroup analysis based on slip stability and whether subjects progressed to a contralateral slip. RESULTS: The SCFE cohort demonstrated a decreased superior epiphyseal extension ratio compared with control (superior EER 0.71 vs. 0.68, P=0.002). There was also a significant downward trend in superior EER from the control subjects (0.71±0.07) to the stable slips (0.69±0.06) to the unstable slips (0.65±0.04) with an overall difference between the groups (P=0.001). Eighteen of 44 (41%) subjects with unilateral stable slips and at least 6 months of follow-up went on to develop SCFE of the contralateral limb. The subjects who developed contralateral slips were younger (11.6±1.2 vs. 12.7±1.4 y, P=0.008); however, there was no difference in superior or anterior epiphyseal extension (P=0.75 and 0.23, respectively). There was no significant linear correlation between Southwick angle and superior or anterior EER (r=0.13 and 0.17, respectively, P>0.05 for both). CONCLUSIONS: Increasing capital femoral epiphyseal extension may confer physeal stability in the setting of SCFE. We propose that this epiphyseal extension reflects an adaptive response to limit physeal stress and reduce the risk for progression to SCFE. LEVEL OF EVIDENCE: Level III-prognostic study.

Gait abnormalities following slipped capital femoral epiphysis treated with in situ fixation.

BACKGROUND: Slipped capital femoral epiphysis (SCFE) is a common disorder in adolescent for which no consensus exists regarding management. The aim of the present study was to analyze gait modifications following SCFE treated with in situ fixation (ISF) and to relate it to radiologic stage. RESEARCH QUESTION: To verify if gait biomechanics are impaired in patients with SCFE and to try to determine a degree of slippage from which gait modifications would appear. METHODS: We evaluated 16 patients treated by ISF for SCFE with slippage ranging from 11° to 61°. Gait variables were compared to normal population according to age and walking speed and were normalized in Z-scores. RESULTS: Spatiotemporal parameters, mechanical and energetic variables were inferior to |1.5| Z-scores and considered as normal. Kinematics showed increase of pelvic tilt and hip adduction. Kinetic variables showed modifications with increased hip extension moment. There was also a strong increase in power of hip extensor. Hip extension moment and power of hip extensors were significantly correlated to radiologic stage. Analysis of ROC curves showed a cut-off value of slippage about 25°-30° affecting kinematics of pelvis and hip and kinetic variables. CONCLUSION: The gait variables were close to normal values. Main modifications were observed in kinematic and kinetic data with a significant increase in extension moment and power generated at the operated hip. This could participate to long-term joint degradation observed in SCFE, even in mild slips. The clinical message is to control regularly SCFE with initial slippage greater than >25-30° to allow for early diagnosis of premature hip osteoarthritis.

Long-term hip function in slipped capital femoral epiphysis treated with in situ pinning.

BACKGROUND: In recent years, there has been a trend toward more aggressive management of slipped capital femoral epiphysis (SCFE) with acute anatomical realignment; however, the literature is unclear with regard to the indications for this. QUESTIONS/PURPOSES: To collect long-term patient-reported outcome scores on a group of SCFE patients using modern hip scores. The second aim was to determine whether there is a threshold level of deformity beyond which patients have predictably poor outcomes following in situ pinning. PATIENTS AND METHODS: Patients presenting with SCFE between 2000 and 2009 completed a survey consisting of three modern hip scores and were classified into poor, intermediate, and good outcome groups. The posterior slope angle (PSA) was used to measure slip deformity. We examined the relationship between patient characteristics and functional outcomes. The relationship between PSA score and overall outcome was examined using receiver operator curve (ROC) analysis. RESULTS: The total study population was 63; 14% patients had poor, 29% had intermediate, and 57% had good functional outcomes. The mean Non-Arthritic Hip Scores (NAHSs) for those with poor outcomes was 51, 76 in the intermediate group, and 95 in the good group ( p <0.001). PSA was significantly lower in those with good functional outcomes. ROC analysis demonstrated that a higher PSA was moderately predictive of a poor clinical outcome (area under the curve of 0.668). In both the poor and intermediate outcome groups, 50% of patients had a PSA of 40° or greater, whereas only 31% of those with good clinical outcomes had PSA of 40° or greater. CONCLUSIONS: A significant proportion of post-SCFE patients have ongoing suboptimal hip function after pinning in situ. Those with a PSA more than 40° have a higher chance of a poor outcome.

Similar femoral growth and deformity with one screw versus two smooth pins for slipped capital femoral epiphysis.

PURPOSE: To compare longitudinal growth and cam deformity of the proximal femur after treatment for slipped capital femoral epiphysis (SCFE) with one screw versus two smooth pins. METHODS: We studied 43 patients (29 males, 14 females; mean age, 12.1 years; range, 9.5-14 years) with idiopathic unilateral SCFE treated with in situ fixation with one cannulated screw (group A, n = 23) or two smooth pins (group B, n = 20). Anteroposterior and frog-leg radiographs of the pelvis were evaluated for each patient at initial presentation, post-operatively and at physeal closure. Longitudinal growth was evaluated using the femoral neck length (FNL), the caput-collum-diaphyseal (CCD) angle, and the articulo-trochanteric distance (ATD). Cam deformity was assessed using the anterior offset α-angle and the head-neck offset ratio (HNOR). The mean follow-up was 5.1 years (range, 4-7 years). RESULTS: Postoperatively, the mean CCD angle was 138.3°, the mean α-angle was 66.1° and the mean HNOR was - 0.030. At physeal closure, mean CCD angle significantly decreased to 133.6°, mean α-angle significantly reduced to 52.1°, and mean HNOR significantly improved to + 0.039. CCD, FNL, ATD, α-angle, and HNOR were not different between groups. CONCLUSIONS: One screw or two smooth pins result in similar longitudinal growth and deformity of the proximal femur after SCFE. The femoral head-neck junction remarkably improves until physeal closure; however, residual cam deformity is not avoided after in situ pinning. The complication rate with smooth pins is higher.