Alpha Angle and Anterior Femoral Neck Offset Identify Different Cohorts of Cam Morphology: An Osteologic Study.

PURPOSE: To explore differences in cam morphology defined by alpha angle (AA) and anterior femoral neck offset (AFNO) in the context of other anthropometric parameters in an osteologic collection to further elucidate whether each measurement tool is identifying the same underlying pathology. METHODS: Anthropometric measurements of 992 cadaveric hips from the Hamann-Todd Osteological Collection were analyzed. Femurs with cam morphology were identified by AA >55° or AFNO <7 mm. Anthropometric parameters stratified by cam morphology were assessed with Wilcoxon rank-sum and Pearson χ2 tests. Multivariate logistic regressions were performed on significant variables in univariate analysis to examine the predictive ability of anthropometric variables to cam morphology. RESULTS: Cam morphology was identified in 242 hips via AA, 344 hips via AFNO, and 123 hips via both measures. Multivariate logarithmic regression analysis demonstrated that sex negatively predicted AA (females with less pathology, ß = -0.14, P = .04), race negatively predicted AA (Blacks with less pathology, ß = -0.21, P < .01), and proximal femoral osteoarthritis was positively associated with AA (ß = 0.16, P = .02), while none of these were associated with AFNO. On the other hand, right-side specimens were associated with AA (ß = 0.15, P = .02) and AFNO (ß = 0.25, P < .01), whereas the combined version was unassociated with both measures. CONCLUSIONS: In conclusion, cam morphology was identified in a modest percentage of osteologic specimens by both AA and AFNO in our study. Further, associations of multiple demographic, anthropometric, and anatomical parameters to AA and AFNO suggest they may identify different subsets of cam morphology. CLINICAL RELEVANCE: Cam morphology identified by AA versus AFNO may represent 2 different pathologic entities. Future studies should assess differences between these measures in a clinical cohort and determine whether these 2 definitions of cam morphology identify different clinical populations.

Treatment of Delbet II/III Pediatric Femoral Neck Fractures With Proximal Femoral Locking Plate Versus Cannulated Screws.

INTRODUCTION: Complications following operative treatment of pediatric femoral neck fractures include nonunion, coxa vara, and avascular necrosis (AVN). Proximal femoral locking plates (PFLPs) provide a fixed-angle construct that may reduce the rates of coxa vara, but their use in pediatric femoral neck fractures has not been studied. The purpose of this study was to evaluate rates of union, coxa vara, and AVN in traumatic pediatric femoral neck fractures treated with PFLP or cannulated screws (CS). METHODS: We retrospectively reviewed all traumatic, nonpathologic Delbet II/III femoral neck fractures in patients below 18 years of age treated with PFLP or CS. All cases had ≥6 months of radiographic follow-up to evaluate for osseous union and AVN. Changes in proximal femoral alignment were determined by measuring injured and contralateral femoral neck-shaft angle and articulotrochanteric distance (ATD) between 6 and 12 months postoperatively. RESULTS: Forty-two patients were identified with mean age at surgery of 10.7±2.9 years (range 3.3 to 16.3 years) and mean follow-up of 36±27 months. Sixteen patients (38%) underwent PFLP fixation, whereas 26 patients (62%) underwent CS fixation. When compared with the CS cohort, the PFLP cohort had a greater proportion of males (87.5% vs. 50%, P =0.02) and Delbet III fractures (68.8% vs. 15.4%, P <0.001). There was no difference between PFLP and CS cohorts with respect to rates of union (81% vs. 88%, respectively, P =0.66), AVN (25% vs. 35%, respectively, P =0.73), or secondary surgery (62% vs 62%, P =0.95). There was no significant difference in neck-shaft angle between injured and contralateral hips in those patients treated with PFLP ( P =0.93) or CS ( P =0.16). However, the ATD was significantly decreased in hips treated with CS compared with the contralateral hip (18.4±4.6 vs. 23.3±4.2 mm, P =0.001), with no significant difference in the PFLP group ( P =0.57). CONCLUSIONS: This study suggests that the use of a PFLP in Delbet II/III femoral neck fractures does not appear to significantly increase nonunion rates or AVN and maintains anatomic ATD when compared with screw fixation. LEVEL OF EVIDENCE: Level III-therapeutic study.

Comparison of Gait and Functional Outcomes Between Open and Arthroscopic Treatment of Adolescent and Young Adult Femoroacetabular Impingement.

BACKGROUND: Management of femoroacetabular impingement (FAI) through an arthroscopic or surgical hip dislocation (SHD) approach has been shown to have similar clinical success and patient-reported outcomes. However, there are limited data comparing functional outcomes. The purpose of this study was to compare gait and functional outcomes of adolescent/young adult patients with FAI treated by either an arthroscopic or open SHD approach. METHODS: We identified prospectively enrolled adolescent/young adult patients (≤20 years old) who underwent surgical treatment for FAI through an SHD or arthroscopic approach. Participants were evaluated in a movement science lab preoperatively and postoperatively (minimum 8 months postoperatively) with barefoot walking and a 30-second single-limb balance trial on the affected side. Participants also completed the Harris Hip Score at the same timepoints. Differences from preoperative to postoperative were determined using a paired-samples t test for each surgical technique, and differences between the SHD and arthroscopic groups were determined using an independent samples t test (α=0.05). RESULTS: Fifty-five participants (42F, 16.2±1.4 y) were tested and grouped by surgical intervention. The SHD and arthroscopy groups consisted of 28 and 27 participants, respectively, with no significant difference between the SHD and arthroscopic cohorts in age (16.4±1.2 vs. 15.9±1.5 y, respectively, P =0.218) or sex distribution (78.6% vs. 74.1% females, respectively, P =0.75). Each group demonstrated significant postoperative improvement in Harris Hip Score (SHD: 64.8±16.4 to 81.8±17.8; arthroscopy: 57.0±16.7 to 84.7±19.7; preoperatively to postoperatively, respectively, both P <0.001). During gait, increased maximum hip flexion was observed following surgical intervention for the SHD group (32.3±5.7 vs. 36.1±5.2, P =0.003). No other clinically significant changes were detected in the SHD or arthroscopic groups preoperatively to postoperatively in trunk, pelvis, or hip kinematics in the coronal plane. During the balance task, neither cohort demonstrated markers of clinically significant abductor dysfunction. However, post operatively, the arthroscopy group was able to balance longer than the SHD group (18.8±7.8 vs. 14.2±2.7 s, respectively, P =0.008), although no differences were detected in trunk or pelvis position in the coronal plane during balance. CONCLUSIONS: Both open SHD and arthroscopic treatment of FAI resulted in improved clinical outcomes with no clinically significant abductor dysfunction 1 year post operatively. However, further study is needed to determine whether more dynamic tasks can potentially elicit subtle differences between the groups. LEVELS OF EVIDENCE: Level II-prospective study.

Outcomes of the Modified Dunn Procedure Versus Delayed Imhauser Osteotomy for Moderate to Severe Stable Slipped Capital Femoral Epiphysis.

BACKGROUND: Traditional management of moderate to severe stable slipped capital femoral epiphysis (SCFE) has been in situ fixation followed by reconstructive surgery if symptoms arise. This delayed approach may lead to irreversible intra-articular damage of the hip over time. The purpose of this study was to compare radiographic and clinical outcomes of the modified Dunn procedure (MDP) versus in situ fixation followed by delayed Imhauser osteotomy (DIO). METHODS: This was a retrospective study from a single institution between 2001 and 2021. Among 250 patients diagnosed with SCFE, a total of 18 (18 hips) treated with MDP and 16 (18 hips) treated with DIO for moderate to severe stable SCFE were included. Most patients who underwent DIO either had concomitant (11/18 hips) or subsequent (2/18 hips) open osteochondroplasty. Mean follow up was 4.7 years (range: 1 to 12.8 y). Radiographs were reviewed to measure Southwick angle, anteroposterior and lateral alpha (α) angles, and femoral head-neck offset ratio preoperatively and at latest follow up. Charts were reviewed for demographics, subsequent surgeries, complications, and Heyman-Herndon clinical outcomes. RESULTS: The amount of deformity correction was greater in the MDP than DIO group based on anteroposterior α angles (mean: 22.3 vs. 11.9 degrees, P =0.046) and femoral head-neck offset ratios (mean: 0.26 vs. 0.12, P =0.001). There was no significant difference in Heyman-Herndon scores (both 16/18, 88.9% good to excellent outcomes, P >0.999). Less reoperations were performed in the MDP than DIO group (2/18, 11.1% vs. 9/18, 50%; P =0.004). AVN occurred in 2/18 hips (11.1%) in the MDP group with both surgeries performed early in the series and underwent prior in situ screw fixation compared with 0/18 hips (0%) in the DIO group ( P =0.486). One patient in the DIO group was later diagnosed with osteoarthritis. CONCLUSIONS: MDP resulted in more anatomic coronal and sagittal plane deformity correction, less reoperations, and similar Heyman-Herndon clinical outcomes compared with DIO. AVN occurred in the MDP group whereas osteoarthritis occurred in the DIO group. These complications must be weighed against improved long-term clinical results for patients who would otherwise be at risk for premature degenerative joint disease due to residual proximal femoral deformity. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Does Screening Ultrasound Timing in Developmental Dysplasia of the Hip Need to be Adjusted for Moderate Preterm and Near-term Infants: A Prospective Study.

INTRODUCTION: An initial screening ultrasound is essential for patients at higher risk of developmental dysplasia of the hip (DDH) due to breech presentation or a family history of DDH. The American Academy of Pediatrics recommends screening ultrasounds to be performed after 6 weeks of age to reduce the rate of false positives. However, there is limited evidence regarding whether these screening ultrasounds need to be adjusted for gestational age in prematurity. The purpose of this study was to evaluate the influence of moderate preterm and near-term births on screening hip ultrasounds for high-risk DDH populations. METHODS: We identified all prospectively enrolled patients in a single-center database referred for screening hip ultrasound for DDH. We included those hips referred for risk factors of DDH, including breech presentation, family history of DDH, or hip click, and excluded those with known dysplasia or referral for hip instability. Each ultrasound was measured by a pediatric radiologist to determine the alpha angle and femoral head coverage. Patients were classified as "premature" if born at <37 weeks gestation or "full term" if born at ≥37 weeks gestation. All patients underwent screening hip ultrasound between 5 and 8 weeks of age. Sonographic markers of dysplasia and the incidences of abnormal ultrasound and Pavlik harness treatment were compared between cohorts. Significance was set at P <0.05. RESULTS: A total of 244 hips in 122 patients were included, 58 hips in the premature cohort and 186 hips in the full-term cohort. The premature cohort had a significantly decreased gestational age compared with the full-term cohort (35.4 ± 1.1 vs 38.5 ± 1.1 wk, respectively, P < 0.001). However, there was no difference between premature and full-term cohorts in sex distribution (69% vs 75%, females, P = 0.39), unadjusted age at the time of ultrasound (6.6 ± 0.7 vs 6.8±0.7 wk, respectively, P = 0.07), or referral reason ( P = 0.14). On hip ultrasound, there was no difference between premature and full-term cohorts with respect to alpha angle (62.6 ± 3.3 vs 62.2 ± 5.3 degrees, P = 0.41), femoral head coverage (54.9 ± 6.3 vs 55.1 ± 10.6, P = 0.19), rate of abnormal ultrasound (18.3% vs 20.7%, respectively, P = 0.68), or the rate of Pavlik harness treatment (0% vs 5.3%, respectively, P = 0.12). DISCUSSION: There was no significant difference in alpha angle or femoral head coverage between premature and full-term patients at 5 to 8 weeks of unadjusted age. This preliminary data suggests that screening ultrasounds can be performed without adjusting for prematurity. LEVEL OF EVIDENCE: Level II, prognostic study.

Abduction Bracing Following Anterior Open Reduction for Developmental Dysplasia of the Hip Does Not Improve Residual Dysplasia or Reduce Secondary Surgery.

BACKGROUND: Abduction bracing is commonly used following open reduction and spica casting of developmental dysplasia of the hip. However, there is little evidence to support or refute this practice that carries associated cost and burden for families. The purpose of this study was to determine the efficacy of abduction bracing after open reduction in improving the acetabular dysplasia and reducing the rate of secondary surgery for residual dysplasia. METHODS: This is a retrospective study of patients treated with open reduction at a single tertiary referral center. Demographic data, severity of dislocation [International Hip Dysplasia Institute (IHDI) class], age at reduction, and casting duration were obtained. Patients were prescribed no bracing, part-time (≤18 h/d), or full-time (≥20 h/d) brace wear based on surgeon preference. Acetabular index (AI) measurements were obtained at cast removal and at 2- and 4-year follow-up. RESULTS: A total of 146 hips underwent open reduction with 61% (89/146) of hips treated with abduction bracing. There was no difference between braced and nonbraced cohorts with regards to sex, age at time of reduction, dislocation severity, cast duration, immediate postcasting AI, or incidence of medial open reduction. There was no difference in hips treated with or without brace following open reduction with regards to AI at 2 years postreduction (31.8±6.7 vs. 30.4±6.1 degrees, P =0.27) or at 4 years postreduction (24.9±6.5 vs. 24.7±6.5 degrees, P =0.97). However, further analysis showed lower mean AI at 2-year follow-up for braced versus nonbraced patients following medial open reduction (30.0±5.7 vs. 34.5±7.0 degrees, P =0.02). This difference was no longer present at 4-year follow-up (26.6±6.8 vs. 24.2±6.6 degrees, P =0.44). However, 4/19 (21%) nonbraced hips underwent secondary surgery for residual dysplasia and were consequently excluded from the AI measurement at 4 years postreduction (compared with 4/39 [10%] braced hips within the same time period). There was no difference in the rate of secondary surgery between braced and nonbraced hips (30% vs. 33%, respectively, P =0.70). Multivariate analysis demonstrated that neither IHDI classification, bracing, nor age at reduction predicted residual dysplasia. CONCLUSIONS: Abduction bracing following anterior open reduction for developmental dysplasia of the hip is not associated with decreased residual dysplasia at 2/4 years postreduction or with decreased secondary surgery. These results suggest that abduction bracing following anterior open reduction may not provide clinical benefit. However, abduction bracing may be beneficial following medial open reduction. A prospective study is necessary to provide more definitive recommendations. LEVEL OF EVIDENCE: Level III-therapeutic study.

The Significance of Isolated Hip Click as a Sign of DDH: Implications on Referral Guidelines.

BACKGROUND: The clinical significance of an isolated hip click remains unclear. The rates of developmental dysplasia of the hip (DDH) in those referred for hip click vary from 0% to 28%. The purpose of this study was to evaluate the rate of DDH in patients prospectively referred for isolated hip click. METHODS: We prospectively enrolled patients referred to a single pediatric orthopaedic center with concern for DDH secondary to isolated hip click felt by the pediatrician on examination. Patients with known sonographic abnormalities or risk factors for DDH (breech presentation or positive family history) were excluded. Ultrasounds were obtained upon initial presentation and defined as abnormal if alpha angle <60 degrees and/or femoral head coverage (FHC) <50%. Mild dysplasia, analogous to Graf IIa physiological immaturity, was defined as alpha angle 50<α<60 and/or <50% FHC in a patient <3 months age. Severe dysplasia was defined as ≤33% FHC, which has been proposed to be sonographically consistent with a hip dislocation. RESULTS: Two hundred fifty-five children were referred for isolated hip click. One hundred eighty-nine patients (74%) had normal ultrasound whereas 66 patients (26%) had sonographic abnormalities (mean age 6.5±6.2 wk at initial ultrasound). Fifty patients (19.6%) demonstrated physiological immaturity, 3 patients (1.2%) demonstrated moderate sonographic dysplasia, and 13 patients (5.1%) had sonographic findings consistent with severe dysplasia or dislocated hip. Hips with severe dysplasia were younger than the remaining population (2.8±2.4 wk vs. 6.6±6.2 wk, P <0.001) with no difference in sex distribution ( P =0.07) or first-born birth order ( P =0.36). For those with sonographic abnormality, 18 (27%) patients were treated with Pavlik harness, 1 (2%) was treated with abduction orthosis, and the remainder (71%) were observed for resolution of physiological immaturity. CONCLUSIONS: Infants with isolated hip click identified by their pediatrician may have higher rates of dysplasia than previously reported. We recommend screening ultrasound and/or orthopaedic referral for all infants with isolated hip click. LEVEL OF EVIDENCE: Level II-prospective prognostic study.

The Role of the Artery of Ligamentum Teres in Revascularization in Legg-Calve-Perthes Disease.

INTRODUCTION: A recent cadaveric study supported that most immature hips are supplied by the artery of ligamentum teres and suggested this medial vascular source may influence the pattern of revascularization in Legg-Calve-Perthes disease (LCPD). The purposes of this study were to characterize the perfusion pattern of the capital femoral epiphysis and determine the role of the artery of ligamentum teres in early revascularization of LCPD. METHODS: Retrospective review of perfusion magnetic resonance imaging (pMRI) from 64 hips in early stage LCPD (Waldenström stage I to IIa) was performed. Two independent graders categorized perfusion pattern based on the presence of perfusion medially (from artery of ligamentum teres) and/or laterally (from the medial femoral circumflex artery) on coronal and sagittal MRI series: type 1-lateral perfusion only, type 2-separate medial and lateral perfusion, or type 3-coalescent medial and lateral perfusion. Lateral pillar classification was obtained for hips that reached mid-fragmentation. RESULTS: We identified 64 patients (75% male) with mean age at diagnosis of 8.5±2.1 years. 36% (23/64) hips underwent pMRI during stage I and 64% (41/64) during stage IIa. pMRI revealed separate and distinct medial and lateral sources of perfusion (type 2) in 50% (32/64) hips. In stage I, the distribution of type 1/2/3 hips was found to be 26%/52%/22%. However, in stage IIa there was a nonsignificant trend toward greater coalescence of the medial and lateral perfusion with a distribution of type 1/2/3 of 7%/49%/44% (P=0.07). There was a nonsignificant trend toward weak negative linear correlation between lower initial perfusion grade and worsened lateral pillar classification at mid-fragmentation (r=-0.25, P=0.05). CONCLUSION: The presence of separate and distinct areas of perfusion of medial and lateral capital femoral epiphysis provides further evidence of the role of the ligamentum teres vessels in revascularization during the early stages of LCPD. The changes in perfusion pattern with disease progression likely reflect that medial femoral circumflex artery and ligamentum teres vessel revascularization occur separately, but ultimately coalesce posteriorly over time. LEVEL OF EVIDENCE: Level II-prognostic study.

The Clinical Significance of Infolded Limbus on Postreduction Arthrogram in Developmental Dysplasia of the Hip.

BACKGROUND: The purpose of this study was to investigate whether presence of an infolded limbus on hip arthrogram at index closed reduction was associated with increased residual dysplasia or secondary surgery. METHODS: We retrospectively reviewed all patients who underwent closed reduction for dysplasia of the hip with a minimum 2-year follow-up between 1980 and 2016. Demographic data was obtained including the age at reduction and severity of dislocation based on the International Hip Dysplasia Institute (IHDI) classification. Arthrograms performed at time of closed reduction were separately reviewed by 3 fellowship-trained pediatric orthopaedic surgeons to evaluate for an infolded limbus. The primary radiographic outcome was acetabular indices at 2 and 4 years postreduction. We also assessed the presence of avascular necrosis and rate of secondary reconstructive surgery for residual dysplasia. RESULTS: A total of 182 hips in 165 patients underwent closed reduction at a mean age of 9.8±4.5 mo and were followed a mean of 9.0±4.9 y. An infolded limbus was identified in 20.3% (37/182) hips with substantial agreement among the 3 graders (Fleiss κ=0.75). The frequency of labral infolding increased with the severity of dislocation (8.8%% of IHDI II, 26.7% IHDI III, and 25.0% of IHDI IV hips; P=0.03). Hips with infolded limbus were older at reduction (12.4±5.3 vs. 9.2±5.8 mo, P=0.001). The mean acetabular index was higher in hips with infolded limbus than hips without at 2 years postreduction (34.8±4.8 vs. 32.6±5.8 degrees, respectively; P=0.04). However, multivariate analysis revealed that only the severity of dislocation predicted dysplasia at 2 years postreduction. No significant difference in acetabular index was seen at 4 years postreduction (27.2±7.4 vs. 25.4±6.5 degrees, P=0.24). There was no difference in avascular necrosis between groups (P=0.74). There was no difference in rate of secondary surgery between hips with labral infolding and those without (35% vs. 30%, respectively; P=0.52). CONCLUSIONS: An infolded limbus was more common in older patients with more severe dislocations. However, it is not associated with increased residual dysplasia or secondary surgery and may have limited utility in decision-making during closed reduction. LEVEL OF EVIDENCE: Level II-prognostic study.

Late Hip Dysplasia After Normal Ultrasound in Breech Babies: Implications on Surveillance Recommendations.

BACKGROUND: There is significant controversy in the literature over rates of late-developing dysplasia following normal screening ultrasound in breech babies, with reported rates varying from 7% to 29%. The purpose of this study is to investigate the rates of radiographic dysplasia in breech babies after a normal ultrasound with a minimum of 1 year of radiographic follow-up. METHODS: This study was an institutional review board-approved prospective study of all patients referred by their pediatrician for concern for developmental dysplasia of the hip between July 2008 and August 2014. We identified all subjects with breech presentation and excluded those with an abnormal initial examination/ultrasound or with <12 months of radiographic follow-up. Anterior-posterior pelvis films were obtained after >12 months and acetabular indices (AIs) were measured and compared with contemporary normative data. Dysplasia was diagnosed as >2 SDs above the mean. RESULTS: A total of 654 patients were referred with a history of a breech presentation, and 150 (22.9%) were found to have clinical instability or sonographic evidence of dysplasia on initial presentation and were observed with serial imaging or treated. Of the remaining 504 subjects with a normal clinical examination and screening ultrasound, 133 (26.4%; 74.4% females, 25.6% males) were followed until at least 12 months of age. Of those presenting at age 12 to 14 months, the mean AI was 0.42±0.83 SD above the mean with a skew towards elevated AIs. At the final follow-up (mean: 20.7±6.7 mo), the mean AI was 0.05±0.92 SD above the mean, and only 3/133 (2.2%) patients had a dysplastic hip. No patients underwent treatment other than an observation during the study period. CONCLUSIONS: One in 5 breech babies have dysplasia at presentation, but late dysplasia following normal screening ultrasound may be less common than previously reported and may be due to our prolonged follow-up period. We recommend surveillance of breech babies with follow-up visits after 12 months of age since earlier visits may offer limited benefits. LEVEL OF EVIDENCE: Level II-prospective prognostic study.

Subtle Slipped Capital Femoral Epiphysis Is not Associated With Idiopathic Cam Morphology.

BACKGROUND: The etiology of idiopathic cam morphology remains unclear. One theory suggests that subtle slipped capital femoral epiphysis (SCFE) leads to proximal femoral changes resulting in cam morphology. The purpose of this study was to evaluate the association between subtle SCFE and cam morphology in a large osteological collection. METHODS: We examined 962 cadaveric hips to measure 2 markers of cam morphology, alpha angle and anterior femoral head-neck offset (AHNO), and a validated, objective marker of subtle SCFE deformity (calcar ridge line offset). When the femur is viewed medially, the calcar ridge line extends from the lesser trochanter proximally along the postero-inferior femoral neck and points toward the fovea. In SCFE-like deformity, the fovea deviates posteriorly from this projected line. Pearson correlations were performed to evaluate for possible association of calcar ridge line offset with alpha angle and AHNO. In addition, a multiple regression analysis was performed to determine the influence of age, alpha angle, and AHNO on calcar ridge line offset. RESULTS: There was no clinically relevant association between the calcar ridge line offset and alpha angle (r=-0.02, P=0.58) or AHNO (r=0.08, P=0.012). Furthermore, specimens whose calcar ridge line deviated 1 SD above the mean (more SCFE-like deformity) had a smaller alpha angle (46.6±9.1 vs. 48.3±10.6, P=0.046) and greater AHNO (0.83±0.19 vs. 0.77±0.16, P<0.001), both reflecting less cam-like morphology. On regression analysis, increasing age and increasing AHNO (decreased cam morphology) predicted increased calcar ridge line offset, though the model accounted for only 1.2% of the variance. CONCLUSIONS: Subtle SCFE-like deformity, as objectively measured from the calcar ridge line, was not predictive of more cam-like morphology, and in fact mild opposite associations were found. Further study is needed to identify other potential etiologies of idiopathic cam morphology. CLINICAL RELEVANCE: We present evidence from a large, well-documented osteological collection indicating that subtle SCFE is not associated with idiopathic cam morphology.

The Association of α Angle on Disease Severity in Adolescent Femoroacetabular Impingement.

BACKGROUND: Femoroacetabular Impingement (FAI) is a common cause of hip pain in adolescent patients. Clinical exam and radiographic markers, such as α angle and lateral center edge angle (LCEA), are commonly used to aid in the diagnosis of this condition. The purpose of this study was to correlate preoperative α angle and LCEA with preoperative symptoms, intraoperative findings, and preoperative and postoperative patient reported outcomes (PROs) in the adolescent patient. METHODS: A retrospective analysis of prospectively collected data was conducted for all patients who underwent operative intervention for FAI at an academic institution over an 11-year period. Preoperative imaging was obtained and measured for LCEA and α angle. PROs (modified Harris Hip Score, Hip Disability and Osteoarthritis Outcome Score, and UCLA score) were collected preoperatively, as well as 1, 2, and 5 years postoperatively. Operative intervention was either open surgical hip dislocation or arthroscopic, and intraoperative disease was graded using the Beck Classification system. Patients with minimum 1-year follow-up were included in statistical analysis. RESULTS: There were 86 hips (64 female hips) included with an average age of 16.3 years (range, 10.4 to 20.5 y), with an average of 37 months of follow-up. There was no correlation between severity of preoperative symptoms or difference between pre and postoperative PROs for both α angle and LCEA. Overall, significant improvement was noted in modified Harris Hip Score, Hip Disability and Osteoarthritis Outcome Score, and UCLA Score (P<0.001 for each). Independent of preoperative symptoms, increased α angle correlated with more severe intraoperative labral disease (P<0.001), and longer length of labral tear (Corr 0.295, P<0.01). Femoral head and acetabular articular cartilage damage did not correlate with α angle or LCEA, nor did overall severity of disease. CONCLUSIONS: In adolescent patients with FAI, increased α angle was found to significantly correlate with labral pathology, including increased length of tear and severity of disease, irrespective of preoperative symptoms or postoperative patient reported outcomes. LEVEL OF EVIDENCE: Level III-retrospective.

Normative Values for Capital Femoral Epiphyseal Extension of the Developing Hip Based on Age, Sex, and Oxford Bone Age.

BACKGROUND: Recent evidence suggests that increasing capital femoral epiphyseal extension may be an adaptive response that underlies the development of most cam morphology, whereas slipped capital femoral epiphysis is associated with its deficiency. However, there is an absence of rigorous data on the normal development of epiphyseal extension in the hip joint in modern adolescents. The aim of this study was to establish normative values for anterior and superior epiphyseal extension in a normal adolescent control population. METHODS: A total of 210 pediatric subjects (420 hips) between the ages of 8 and 17 years old at the time of presentation who received pelvic radiographs were retrospectively reviewed. Basic demographic data were collected. All subjects with underlying hip pathology were excluded. Epiphyseal extension ratio (EER) was measured, defined as the ratio of extension of the capital femoral epiphysis down the femoral neck relative to the diameter of the femoral head. Superior EER was measured on the anterioposterior view and anterior EER on the frog-leg lateral view bilaterally. Skeletal maturity was graded based on Oxford bone age (OBA) at the proximal femur. RESULTS: The superior EER increased from 0.63±0.05 at age 8 to 0.80±0.05 at age 17. The anterior EER similarly increased from 0.56±0.06 at age 8 to 0.74±0.05 at age 17. The superior and anterior EERs increased with age in a linear fashion for males (r=0.80 and 0.75, respectively) and females (r=0.67 and 0.65) through physeal closure. When subjects were standardized by the OBA stage of the femoral head, females and males showed no statistical difference at OBA stages 6, 7 or 8. CONCLUSIONS: Superior and anterior EER increased throughout adolescent development until physeal closure. When controlling for skeletal maturity, there were no significant differences between sexes. This normative data may help guide future management and research of slipped capital femoral epiphysis and cam morphology. LEVEL OF EVIDENCE: Level II, Diagnostic.

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.

Pediatric Supracondylar Humerus Fractures: AAOS Appropriate Use Criteria Versus Actual Management at a Pediatric Level 1 Trauma Center.

OBJECTIVES: The purpose of this study was to characterize management of supracondylar humerus fractures (SCHFs) at a level 1 trauma center and identify factors contributing to divergence in management from American Academy of Orthopedic Surgeons (AAOS) the Appropriate Use Criteria (AUC) recommendations. METHODS: A query revealed 556 patients with diagnoses of SCHF between 2013 and 2015 at a pediatric level 1 trauma center. Patients were excluded if they were younger than 2 years of age, older than 12 years of age, were polytrauma patients, or if there was not sufficient clinical or radiographic documentation, resulting in 449 patients. Urgent/emergent intervention was defined as surgery within 8 hours of presentation. Binomial logistic regression assessed whether various factors predicted operative versus nonoperative management. RESULTS: Operative management was undertaken in 0/208 (0%) type I fractures, 61/106 (57.0%) type II fractures, and 135/135 (100%) type III fractures. Comparison with AUC recommendations revealed disagreement in 31% (138/449) of cases. Among 449 patients, 44 were treated nonoperatively despite AUC recommendations for operative treatment. All 44 of these patients were type II SCHFs managed nonoperatively. There were no definitive cases of malalignment or loss of alignment in these nonoperative cases. Factors predictive of operative management were anterior humeral line not intersecting the capitellum (odds ratio, 200; P<0.001) and increasing age (odds ratio, 1.53; P=0.024). The AUC more frequently recommended urgent/emergent operative intervention (148/449, 33.0%) than was performed at our pediatric level 1 trauma center (50/449, 11.1%). The majority of this disagreement (94/98, 95.9%) consisted of uncomplicated type III SCHF treated operatively in >8 hours. None of these patients developed compartment syndrome or required an open reduction. CONCLUSIONS: The American Academy of Orthopedic Surgeons AUC recommended operative and urgent/emergent intervention more frequently than was performed at a level 1 pediatric trauma center. Patient age and alignment of the anterior humeral line with the capitellum, though not specifically addressed in the AUC, were most predictive of operative versus nonoperative management at our institution.

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.

Micrometastatic Drug Screening Platform Shows Heterogeneous Response to MAP Chemotherapy in Osteosarcoma Cell Lines.

BACKGROUND: Approximately 80% of patients with osteosarcoma harbor subclinical pulmonary micrometastases at diagnosis. Conventional chemotherapy includes methotrexate, doxorubicin, and cisplatin (MAP); however, this regimen and thus overall survival (60%-70%) have remained largely unchanged for 30 years. It therefore is necessary to identify novel therapeutics targeting the metastatic progression of osteosarcoma. QUESTIONS/PURPOSES: This laboratory study explored application of osteosarcoma spheroids (sarcospheres) for drug screening with the following purposes: (1) to characterize sarcosphere size; (2) to establish accurate measurement of sarcosphere growth; (3) to confirm sarcosphere uniformity; and (4) to apply the platform to evaluate MAP chemotherapy. METHODS: Sarcospheres were first characterized to establish accurate measurement of sarcosphere growth and uniform production. The refined platform then was applied to evaluate MAP chemotherapy to validate its use in drug screening. Sarcospheres were generated from highly metastatic human cell lines (143B, MG-63.3, and LM7) by centrifugation to form three-dimensional aggregates modeling micrometastases. Sarcospheres were matured for 24 hours and then incubated with or without drug from Days 0 to 2. Size was assessed by diameter and volume using brightfield microscopy. Growth was measured by volume and resazurin reduction in viable cells. Sarcosphere uniformity was assessed by diameter and resazurin reduction at Day 0 and the Z' factor, a measure of assay suitability for high-throughput screening, was calculated at Day 2. Sarcospheres were treated with individual MAP agents (0 to 1000 µmol/L) to determine concentrations at which 50% of growth from Days 0 to 2 was inhibited (GIC50). Cell lines resistant to MAP in sarcospheres were treated in monolayer for comparison. RESULTS: Sarcosphere diameter and growth from Days 0 to 2 were quantitatively dependent on the number of cells seeded and the cell line used. Accurate measurement of growth occurred after resazurin incubation for 6 hours, without EDTA-mediated permeabilization, and was correlated with the number of cells seeded and sarcosphere volume for 143B (Spearman's r: 0.98; p < 0.001), MG-63.3 (0.99; p < 0.001), and LM7 (0.98; p < 0.001). Sarcospheres met established criteria for screening applications as mean Z' factors were greater than 0.5 for all cell lines. Response to MAP therapy was cell line-dependent, because MG-63.3 and LM7 sarcospheres exhibited greater than 2000-fold resistance to methotrexate (GIC50 = 88 ± 36 µmol/L and 174 ± 16 µmol/L, respectively) compared with the 143B cell line (GIC50 = 0.04 ± 0.01 µmol/L; p < 0.001 for MG-63.3 and LM7). MG-63.3 monolayers were more sensitive to methotrexate (GIC50 = 0.01 ± 0.01 µmol/L; p < 0.001) than MG-63.3 sarcospheres, whereas LM7 monolayers remained chemoresistent (GIC50 not reached). CONCLUSIONS: This study developed and validated a drug screening platform for progression of osteosarcoma micrometastases. It also highlights heterogeneity among osteosarcoma cell lines. These findings appear to reflect known patient-to-patient heterogeneity and underscore the importance of evaluating multiple tumor models when testing drugs for the treatment of osteosarcoma. CLINICAL RELEVANCE: The described approach is a promising starting point for drug screening in osteosarcoma because it is tailored to evaluate micrometastatic disease. A reliable and rapid method to identify novel therapeutics is critical to improve stagnant outcomes for patients with osteosarcoma.

Femoral Version and Tibial Torsion are Not Associated With Hip or Knee Arthritis in a Large Osteological Collection.

BACKGROUND: Tibial torsion and femoral anteversion are common rotational abnormalities in children, and their courses are most often benign and self-resolving. Although neither usually requires surgical treatment, the decision to perform a derotational osteotomy is usually based on the degree of functional impairment. Neither condition is thought to influence the development of osteoarthritis of the hip or knee; however, to date there have been no large scale studies confirming this. METHODS: Tibial torsion and femoral version in 1158 cadaveric tibiae and femora were measured using a camera setup based on previously described radiographic landmarks. Any specimens with obvious traumatic, rheumatic, or metabolic abnormalities were excluded. Degenerative joint disease of the hip and knee were each graded from 0 to 6. Correlations between tibial torsion, femoral version, age, race, and sex with osteoarthritis of the hip and knee joints were evaluated with multiple regression analysis. RESULTS: The mean and SDs of tibial torsion and femoral anteversion were 7.9±8.8 and 11.4±12.0 degrees, respectively. African Americans had significantly increased tibial torsion (5.1±8.7 vs. 9.2±8.5 degrees, P<0.0005) and greater femoral anteversion (14.1±11.9 vs. 10.2±11.8 degrees, P<0.0005) compared with whites. The average grades for hip and knee osteoarthritis were 3.1±1.4 and 2.7±1.4. Using multiple regression analysis neither tibial torsion nor femoral version were independent predictors of hip or knee arthritis (P>0.05 for all). DISCUSSION: This study confirmed previously reported differences in the rotational profiles between races and sexes. However, neither tibial torsion nor femoral anteversion had a significant influence on the development of arthritis of the hip or knee. CLINICAL RELEVANCE: These results support the practice of treating tibial torsion and femoral anteversion based on the symptomatology of the patient. Parents of asymptomatic children can be reassured that long-term consequences are unlikely.

Increased and decreased pelvic incidence, sagittal facet joint orientations are associated with lumbar spine osteoarthritis in a large cadaveric collection.

PURPOSE: Degenerative joint disease of the lumbar spine is a pervasive problem in healthcare; however, its aetiology and risk factors remain poorly defined. There have been recent attempts to correlate the anatomic parameters of facet angle and pelvic incidence with spine osteoarthritis, although data remains limited. The purpose of this experiment was to determine how age, gender, race, facet angle, tropism, and pelvic incidence correlate to facet joint osteoarthritis in the lumbar spine. METHODS: A total of 576 cadaveric lumbar spines were obtained. Using validated techniques, facet angle, tropism, and pelvic incidence were measured. Osteoarthritis of the lumbar spines was graded from 0-4 at each level. Correlations between osteoarthritis and age, gender, facet angle, tropism, and pelvic incidence were evaluated with regression analysis. RESULTS: Facet angle became more coronally oriented, and facet tropism increased from L1-L2 to L5-S1. Arthritis was highest at the L4-L5 joint (2.2 ± 1.1), compared to the L5-S1 (2.1 ± 1.1), L3-L4 (1.9 ± 1.1), L2-L3 (1.5 ± 1.0) and L1-L2 (1.0 ± 1.0) joints (p < 0.001). Age was the strongest predictor of arthritis at all levels (standardized betas 0.342 through 0.494, p < 0.001). Correlations between gender, race and osteoarthritis were not significant at any level. A decreased facet angle was predictive of increased arthritis at each joint level (standardized betas -0.091 through -0.153, p < 0.05 for all). Tropism was a predictor of increased arthritis at caudal levels. Pelvic incidence was a predictor of increased arthritis at L3-L4 (standardized beta 0.080, p = 0.02), L4-L5 (standardized beta 0.081,p = 0.02), and L5-S1 (standardized beta 0.100, p = 0.01). CONCLUSIONS: Facet arthritis was correlated with a more sagittal orientation of the facet joints, increased tropism, and perturbations of pelvic incidence.

Pelvic incidence: an anatomic investigation of 880 cadaveric specimens.

PURPOSE: Pelvic incidence is a position- and posture-independent parameter used to quantify sagittal balance of the spine, sacrum, pelvis and hips. Its functional consequences have been associated with a number of different pathologies of the spine. However, there exists considerable controversy over which demographic features contribute to the development of pelvic incidence. METHODS: 880 cadaveric skeletons from the Hamann-Todd Osteological Collection were obtained. The innominate bones and sacrum were reconstructed, and pelvic incidence was measured using a previously validated technique. Specimens with obvious fracture, infection, or rheumatologic conditions were excluded from study. Descriptive data of age at the time of death, gender, race and height were collected. RESULTS: The average pelvic incidence was 46.0° ± 11.0°. Pelvic incidence did not change with age (r = 0.026, p = 0.288). There was no difference in pelvic incidence measurements between females and males (47.2° ± 13.8° vs. 45.8° ± 10.4°, respectively; p = 0.257), although this analysis was under-powered. Pelvic incidence was higher in African-Americans compared to Caucasians (48.9° ± 11.0° vs. 44.9° ± 10.8°; p = 0.001). There was no association between height and pelvic incidence (r = -0.042, p = 0.164). CONCLUSIONS: This study represents the largest single cohort of pelvic incidence measurements reported in the literature. Our data suggest that pelvic incidence does not change with age or height, although racial differences do exist. As spine care providers increasingly rely on pelvic incidence as an important means to quantify sagittal balance, the normative data provided herein will provide an essential reference.