Does the Capital Femoral Physis Bony MorphologyDiffer in Children with Symptomatic Cam-type Femoroacetabular Impingement.

BACKGROUND: The epiphyseal tubercle, the corresponding metaphyseal fossa, and peripheral cupping are key stabilizers of the femoral head-neck junction. Abnormal development of these features in the setting of supraphysiologic physeal stress under high forces (for example, forces that occur during sports activity) may result in a cam morphology. Although most previous studies on cam-type femoroacetabular impingement (FAI) have mainly focused on overgrowth of the peripheral cupping, little is known about detailed morphologic changes of the epiphyseal and metaphyseal bony surfaces in patients with cam morphology. QUESTIONS/PURPOSES: (1) Does the CT-based bony morphology of the peripheral epiphyseal cupping differ between patients with a cam-type morphology and asymptomatic controls (individuals who did not have hip pain)? (2) Does the CT-based bony morphology of the epiphyseal tubercle differ between patients with a cam-type morphology and asymptomatic controls? (3) Does the CT-based bony morphology of the metaphyseal fossa differ between patients with a cam-type morphology and asymptomatic controls? METHODS: After obtaining institutional review board approval for this study, we retrospectively searched our institutional database for patients aged 8 to 15 years with a diagnosis of an idiopathic cam morphology who underwent a preoperative CT evaluation of the affected hip between 2005 and 2018 (n = 152). We excluded 96 patients with unavailable CT scans and 40 patients with prior joint diseases other than cam-type FAI. Our search resulted in 16 patients, including nine males. Six of 16 patients had a diagnosis of bilateral FAI, for whom we randomly selected one side for the analysis. Three-dimensional (3-D) models of the proximal femur were generated to quantify the size of the peripheral cupping (peripheral growth of the epiphysis around the metaphysis), epiphyseal tubercle (a beak-like prominence in the posterosuperior aspect of the epiphysis), and metaphyseal fossa (a groove on the metaphyseal surface corresponding to the epiphyseal tubercle). A general linear model was used to compare the quantified anatomic features between the FAI cohort and 80 asymptomatic hips (aged 8 to 15 years; 50% male) after adjusting for age and sex. A secondary analysis using the Wilcoxon matched-pairs signed rank test was performed to assess side-to-side differences in quantified morphological features in 10 patients with unilateral FAI. RESULTS: After adjusting for age and sex, we found that patients with FAI had larger peripheral cupping in the anterior, posterior, superior, and inferior regions than control patients who did not have hip symptoms or radiographic signs of FAI (by 1.3- to 1.7-fold; p < 0.01 for all comparisons). The epiphyseal tubercle height and length were smaller in patients with FAI than in controls (by 0.3- to 0.6-fold; p < 0.02 for all comparisons). There was no difference in tubercle width between the groups. Metaphyseal fossa depth, width, and length were larger in patients with FAI than in controls (by 1.8- to 2.3-fold; p < 0.001 for all comparisons). For patients with unilateral FAI, we saw similar peripheral cupping but smaller epiphyseal tubercle (height and length) along with larger metaphyseal fossa (depth) in the FAI side compared with the uninvolved contralateral side. CONCLUSION: Consistent with prior studies, we observed more peripheral cupping in patients with cam-type FAI than control patients without hip symptoms or radiographic signs of FAI. Interestingly, the epiphyseal tubercle height and length were smaller and the metaphyseal fossa was larger in hips with cam-type FAI, suggesting varying inner bone surface morphology of the growth plate. The docking mechanism between the epiphyseal tubercle and the metaphyseal fossa is important for epiphyseal stability, particularly at early ages when the peripheral cupping is not fully developed. An underdeveloped tubercle and a large fossa could be associated with a reduction in stability, while excessive peripheral cupping growth would be a factor related to improved physeal stability. This is further supported by observed side-to-side differences in tubercle and fossa morphology in patients with unilateral FAI. Further longitudinal studies would be worthwhile to study the causality and compensatory mechanisms related to epiphyseal and metaphyseal bony morphology in pathogenesis cam-type FAI. Such information will lay the foundation for developing imaging biomarkers to predict the risk of FAI or to monitor its progress, which are critical in clinical care planning. 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.

What Is the Accuracy and Reliability of the Peritubercle Lucency Sign on Radiographs for Early Diagnosis of Slipped Capital Femoral Epiphysis Compared With MRI as the Gold Standard?

BACKGROUND: The diagnosis of slipped capital femoral epiphysis (SCFE) often is delayed. Although lack of clinical suspicion is the main cause of delayed diagnosis, typical radiographic changes may not be present during the initial phases of SCFE. The peritubercle lucency sign for follow-up of the contralateral hip in patients with unilateral SCFE may be beneficial in assisting the early diagnosis. However, the accuracy and reliability of this sign in patients with SCFE is unknown. QUESTIONS/PURPOSES: (1) What is the accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the peritubercle lucency sign on radiographs for the early diagnosis of SCFE compared with MRI as the gold standard? (2) What are the interobserver and intraobserver reliabilities of the peritubercle lucency sign on radiographs? METHODS: Between 2000 and 2017, 71 patients underwent MRI for an evaluation of pre-slip or a minimally displaced SCFE. Sixty percent of hips (43 of 71) had confirmed SCFE or pre-slip based on the presence of hip pain and MRI changes, and these patients underwent in situ pinning. Three independent experienced observers reviewed MR images of the 71 hips and agreed on the presence of a juxtaphyseal bright-fluid signal suggesting bone marrow edema in these 43 hips with SCFE, and absence MRI changes in the remaining 28 hips. The same three experienced observers and two inexperienced observers, including a general radiologist and an orthopaedic surgery resident, blindly assessed the radiographs for the presence or absence of the peritubercle lucency sign, without information about the diagnosis. Diagnostic accuracy measures including sensitivity, specificity, PPV, and NPV were evaluated. Intraobserver and interobserver agreements were calculated using kappa statistics. RESULTS: The overall accuracy of the peritubercle lucency sign on radiographs was 94% (95% CI 91 to 96), sensitivity was 97% (95% CI 95 to 99), specificity was 89% (95% CI 90 to 96), PPV was 93% (95% CI 90 to 96), and NPV was 95% (95% CI 92 to 99). All accuracy parameters were greater than 85% for the five observers, regardless of experience level. Intraobserver agreement was perfect (kappa 1.0), and interobserver agreement was excellent for the peritubercle lucency sign on radiographs across the five observers (kappa 0.81 [95% CI 0.73 to 0.88]). The reliability was excellent for experienced observers (kappa 0.88 [95% CI 0.74 to 1.00]) and substantial for inexperienced observers (kappa 0.70 [95% CI 0.46 to 0.93]), although no difference was found with the numbers available (p = 0.18). CONCLUSIONS: The peritubercle lucency sign on radiographs is accurate and reliable for the early diagnosis of SCFE compared with MRI as the gold standard. Improving the early diagnosis of SCFE may be possible with increased awareness, high clinical suspicion, and a scrutinized evaluation of radiographs including an assessment of the peritubercle lucency sign. LEVEL OF EVIDENCE: Level III, diagnostic 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.

The modified Dunn procedure provides superior short-term outcomes in the treatment of the unstable slipped capital femoral epiphysis as compared to the inadvertent closed reduction and percutaneous pinning: a comparative clinical study.

PURPOSE: The aim of this study was to compare clinical outcomes and radiographic correction after modified Dunn procedure versus inadvertent closed reduction and percutaneous pinning for the treatment of unstable slipped capital femoral epiphysis (SCFE). METHODS: We evaluated 45 patients with unstable SCFE treated using the modified Dunn procedure (n = 27) or percutaneous pinning (n = 18) during a minimum follow-up of one year. Clinical outcomes were assessed using the Heyman and Herndon scores. The Southwick angle, alpha angle, and femoral head-neck offset were used to assess radiographic correction. The occurrence of complications and unplanned re-operations were recorded. RESULTS: At latest follow-up, 67% (18/27) in the modified Dunn procedure group and 28% (5/18) in the in situ pinning group had good or excellent Heyman and Herndon outcomes (p = 0.016). The morphology of the femoral head and neck was improved in the modified Dunn procedure group compared to percutaneous pinning (Southwick angle, alpha angles; femoral head-neck offset; p < 0.001). The proportion of osteonecrosis (26 vs. 28%; p > 0.999) and unplanned re-operations (26 vs. 33%; p = 0.894) was similar in both groups. CONCLUSION: Compared to inadvertent reduction and percutaneous pinning, the modified Dunn procedure provided better clinical and radiographic outcomes with similar proportion of osteonecrosis and unplanned re-operations following an unstable SCFE.

Morphologic Features of the Contralateral Femur in Patients With Unilateral Slipped Capital Femoral Epiphysis Resembles Mild Slip Deformity: A Matched Cohort Study.

BACKGROUND: Hip osteoarthritis has been reported in the contralateral hip in patients who had been treated for unilateral slipped capital femoral epiphysis (SCFE) during adolescence. Although this might be related to the presence of a mild deformity, the morphologic features of the contralateral hip in unilateral SCFE remains poorly characterized. QUESTIONS/PURPOSES: Do measurements of (1) femoral head-neck concavity (α angle and femoral head-neck offset), (2) epiphyseal extension into the metaphysis (epiphyseal extension ratio and epiphyseal angle), and (3) posterior tilt of the epiphysis (epiphyseal tilt angle) differ between the contralateral asymptomatic hips of patients treated for unilateral SCFE and hips of an age- and sex-matched control population without a history of hip disease? METHODS: From January 2005 to May 2015, 442 patients underwent surgical treatment for SCFE at our institution. Patients were included in this study if they had a pelvic CT scan and unilateral SCFE defined by pain or a limp in one hip without symptoms or obligatory external rotation with flexion in the contralateral hip and no evidence of SCFE findings on available radiographs. Seventy-two (16%) patients had a pelvic CT scan; however, 32 patients with bilateral involvement and one patient with CT imaging of inadequate quality for multiplanar reformatting were excluded. Thirty-nine control subjects were identified from a preexisting database of patients who underwent pelvic CT between January 2008 and January 2014 for assessment of abdominal pain in the setting of suspected appendicitis. Patients in the contralateral asymptomatic hip group then were matched to control subjects using a modified nearest-neighbor approach based on sex and age. Patients in the contralateral asymptomatic hip group were separated in males and females and control subjects were assigned to an appropriate sex category. Then subjects closest in age were matched with each patient. If more than one subject was available as a match for a given patient, the control subject with the closest BMI was selected. The contralateral asymptomatic hip and matched groups had 19 (49%) male patients and 20 (51%) female patients, with mean ages (± SD) of 16 (± 3) years and 16 (± 3) years, respectively (p = 0.16). Matched subjects had a mean BMI of 25 ± 4 kg/m and the mean BMI difference among groups was 5 ± 5 kg/m (p < 0.001). According to the Southwick radiographic criteria nine patients (23%) had a mild slip, 10 (26%) had a moderate slip, and 19 (49%) had severe SCFE. The α angle and femoral head-neck offset, epiphyseal extension ratio and epiphyseal angle, and epiphyseal tilt were assessed in the anterior, anterosuperior, and superior femoral planes on radially reformatted CT by one observer not involved in clinical care of the patients. Inter- and intrarater reliability were determined on 10 randomly selected hips assessed by the same observer and another observer and it was found to be excellent for all femoral measurements (intraclass correlation coefficients > 0.85). Paired t-tests were used to compare the contralateral asymptomatic hip of patients with SCFE and control hips. RESULTS: The head-neck junction showed decreased concavity in the contralateral femur of patients with unilateral SCFE compared with control subjects as assessed by slightly higher mean α angle in the anterosuperior plane (51° ± 6° versus 48° ± 7°; mean difference, 2°, 95% CI, 0°-5°; p = 0.04) and slightly higher median α angle in the superior plane (45° [range 37°-72°] versus 42° [range, 36°-50°], median shift, 4° [range, 2°-5°], p < 0.001), and slightly lower head-neck offset (anterosuperior: 5 mm ± 2 mm versus 6 mm ± 2 mm, mean difference, -1mm [range, -1 mm to 0 mm], p = 0.009; superior: median, 6 mm [range, 1 mm-8 mm] versus 7 mm [range, 5 mm-9 mm]; median shift, -1 mm [range, -1 mm to 0 mm], p < 0.001). There was less epiphyseal extension in the anterosuperior plane as evidenced by lower epiphyseal extension ratio (72% ± 6% versus 75% ± 6%; p = 0.005) and higher epiphyseal angle (64° ± 7° versus 60° ± 7°; p = 0.003). The epiphysis was slightly more posteriorly tilted (anterior plane tilt: 8° ± 6° versus 5° ± 4°; p = 0.03) and more vertically oriented (superior plane tilt 11° ± 5° versus 14° ± 4°; p = 0.006) in the contralateral asymptomatic hip of patients with SCFE. CONCLUSIONS: The contralateral femur in patients treated for unilateral SCFE shows decreased concavity of the head-neck junction assessed by a higher α angle and reduced head-neck offset compared with age- and sex-matched control subjects. Because we noted lower epiphyseal extension but a more posteriorly tilted epiphysis, the reduced concavity resembles a mild slip deformity rather than an idiopathic cam morphologic feature. CLINICAL RELEVANCE: Although we noted a difference in the morphologic features of the head-neck junction between the two groups, the clinical significance is unclear because most differences were rather small. However, our findings suggest that the uninvolved hip in patients with unilateral SCFE may have a subtle asymptomatic cam morphologic feature that may be identified only with advanced imaging (CT or MRI). Future studies should investigate whether these morphologic changes influence development of contralateral SCFE or symptomatic femoroacetabular impingement in the contralateral hip of patients with unilateral SCFE and establish thresholds for indication of prophylactic fixation to avoid further slip and worsening of the morphologic features of the cam-femoroacetabular impingement.

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

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

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

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

The acetabulum in healed Legg-Calvé-Perthes disease is cranially retroverted and associated with global reduction of femoral head coverage: a matched-cohort study.

To evaluate the acetabular morphology in healed Legg-Calvé-Perthes disease after skeletal maturity using computed tomography (CT) scan and to compare with matched controls. We identified 33 (37 hips) patients with healed Legg-Calvé-Perthes disease and closed triradiate cartilage who underwent pelvic CT scan. Each patient was matched based on sex, age and side to a subject with no history of hip disease who had undergone pelvic CT evaluation because of abdominal pain. Both cohorts had 23 (70%) males and mean age of 16.4-16.5 ± 3.6 years. Two independent readers assessed lateral center-edge angle (LCEA), acetabular inclination angle (IA), acetabular depth-width ratio (ADR), acetabular version 10 mm below the dome (cranial) and at the acetabular center and anterior (AASA) and posterior acetabular sector angles (PASA). All measurements had good to excellent interobserver agreement (intraclass coefficients ≥ 0.87). The hips in the Legg-Calvé-Perthes disease cohort had a smaller mean ± standard deviation (SD) superior, anterior and posterior acetabular coverage as assessed by LCEA (13.2° ± 10.7° versus 28.2° ± 3.4°; P < 0.0001), IA (11.6° ± 6.7° versus 3.5° ± 2.8°; P < 0.0001), AASA (52.4° ± 9.5° versus 59.3° ± 5.0°; P = 0.001) and PASA (79.3° ± 5.9° versus 92.3° ± 5.5°; P < 0.0001) compared with controls. The acetabulum was shallower (ADR 287 ± 45 versus 323 ± 28; P = 0.0002) and the acetabular version was decreased cranially (0.4°±9.2° versus 8.2°±6.8°; P = 0.0002) and at the acetabular center (13.7°±5.1° versus 17.2° ±3.8°; P = 0.004) in Legg-Calvé-Perthes disease hips. After skeletal maturity, hips with healed Legg-Calvé-Perthes disease have shallower and more cranially retroverted acetabula, with globally reduced coverage of the femoral head compared with age-, sex- and side-matched control hips.

Contralateral slip after unilateral slipped capital femoral epiphysis is associated with acetabular retroversion but not increased acetabular depth and overcoverage.

Overcoverage of the femoral head by the acetabulum, increased acetabular depth and retroversion have been associated with the etiology of slipped capital femoral epiphysis (SCFE). However, limited evidence exists about the impact of the acetabular morphology on the development of a contralateral slip following an initial presentation of unilateral SCFE. We aimed to investigate whether acetabular overcoverage as assessed by an increased lateral center-edge angle (LCEA) and low Tönnis angle, increased acetabular depth assessed by the acetabular depth-width ratio (ADR) and the presence of coxa profunda; and acetabular retroversion assessed by the presence of the crossover sign were associated with a contralateral slip in patients presenting with unilateral SCFE. We evaluated 250 patients with initial diagnosis of unilateral SCFE (average age, 12.5 ± 1.7 years), who had not undergone prophylactic fixation on the contralateral hip for a median follow-up of 49 months (interquartile range: 25-76 months). Endpoints were the development of a contralateral slip (70 patients, 28%) or skeletal maturity assessed by complete closure of the proximal femoral growth plate (180 patients, 72%). We measured the LCEA, Tönnis angle, ADR, and the coxa profunda sign on an anteroposterior pelvic radiograph. The crossover sign was assessed in 208 hips who had a secondary ossification center in the posterior acetabular rim. For each additional degree of LCEA, the odds of contralateral slip decreased 8% [odds ratio = 0.92; 95% confidence interval (CI), 0.87-0.98; P = 0.009]. Tönnis angle (P = 0.11), ADR (P = 0.20) and coxa profunda (p = 0.37) had no association with a contralateral slip. The presence of crossover sign increased two and half times the odds for a contralateral slip (odds ratio = 2.5; 95% CI = 1.12-5.64; P = 0.03). Acetabular retroversion, but not acetabular overcoverage or increased acetabular depth, was associated with contralateral SCFE development in patients with unilateral SCFE. Level of evidence: prognostic level II.

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

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

Age- and sex-specific morphologic changes in the metaphyseal fossa adjacent to epiphyseal tubercle in children and adolescents without hip disorders.

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

Increased body mass index percentile is associated with decreased epiphyseal tubercle size in asymptomatic children and adolescents with healthy hips.

PURPOSE: To investigate whether body mass index (BMI) percentile impacts the morphology of the capital femoral epiphysis in children and adolescents without hip disorders. METHODS: We assessed 68 subjects with healthy hips who underwent a pelvic CT for evaluation of appendicitis. There were 32 male patients (47%) and the mean age was 11.6 years (sd 2.3). The BMI (k/m2) was calculated for sex- and age-related percentiles according to the Centers for Disease Control and Prevention growth charts. CT images were segmented, and the epiphysis and metaphysis were reformatted using 3D software. We measured the epiphyseal tubercle (height, width and length), the metaphyseal fossa (depth, width and length) and the peripheral cupping of the epiphysis. All measurements were normalized to the diameter of the epiphysis. Pearson's correlation analysis was used to assess the correlations between the variables measured and BMI percentile adjusted for age. RESULTS: Following adjustment to age, increased BMI correlated to decreased tubercle height (r =-0.34; 95% confidence interval (CI) -0.53 to -0.11; p = 0.005), decreased tubercle length (r = -0.32; 95%CI -0.52 to -0.09; p = 0.008) and decreased tubercle width (r = -0.3; 95% CI -0.5 to -0.07; p = 0.01). There was no correlation between BMI and metaphyseal fossa and epiphyseal cupping measurements. CONCLUSION: The association between increased BMI percentile and decreased epiphyseal tubercle size, without changes of the metaphyseal fossa and peripheral cupping suggests another morphological change of the femur that may be associated with decreased growth plate resistance to shear stress. Further study is necessary to investigate whether the epiphyseal tubercle size plays a role in the pathogenesis of slipped capital femoral epiphysis in obese children and adolescents. LEVEL OF EVIDENCE: Level IV.

The metaphyseal fossa surrounding the epiphyseal tubercle is larger in hips with moderate and severe slipped capital femoral epiphysis than normal hips.

PURPOSE: To compare the 3D morphology of the metaphyseal fossa among mild, moderate and severe stable slipped capital femoral epiphysis (SCFE) and normal hips. METHODS: We identified pelvic CT of 51 patients (55% male; mean 12.7 years (sd 1.9; 8-15)) with stable SCFE. In all, 16 of 51 hips (31%) had mild, 14 (27%) moderate and 21 (41%) severe SCFE. A total of 80 patients (50% male; mean age 11.5 years (sd 2.3; 8 to 15)) with normal hips who underwent pelvic CT due to abdominal pain made up the control cohort. CT scans were segmented, and the femur was reformatted using 3D software. We measured the metaphyseal fossa depth, width, length and surface area after the epiphysis was subtracted from the metaphysis in the 3D model. RESULTS: The metaphyseal fossa width was significantly larger in severe (adjusted difference: 6.9%; 95% confidence interval (CI) 2.1 to 11.8; p = 0.001), moderate (6.5%; 95% CI 0.8 to 12.2; p = 0.02) and mild SCFE (6.2%; 95% CI 0.8 to 11.6; p = 0.01), in comparison with normal hips. Severe SCFE showed larger fossa length compared with mild SCFE (6.8%; 95% CI 0.6 to 13.0; p = 0.02) and normal hips (6.0%; 95% CI 1.4 to 10.6; p = 0.004). The fossa surface area was larger in severe (3.5%; 95% CI 1.3 to 5.7; p < 0.001) and moderate SCFE (2.7%; 95% CI 0.1 to 5.2; p = 0.03) when compared with normal hips. There were no differences in fossa depth between SCFE and normal hips. CONCLUSION: The metaphyseal fossa is wider and more extensive but not deeper in hips with moderate and severe SCFE in comparison with normal hips. Although hips with severe SCFE had larger length and surface area than mild SCFE hips, further research is needed to clarify whether enlargement of the metaphyseal fossa is a consequence of slip progression. LEVEL OF EVIDENCE: III.

Identification of the Artery of Adamkiewicz Using Multidetector Computed Tomography Angiography (MCTA).

Objective The aim of the present study is to evaluate the artery of Adamkiewicz by multidetector computed tomography angiography (MCTA) in a Brazilian population. Methods Two independent observers evaluated 86 coronary MCTA examinations. The variables studied included the identification of the artery of Adamkiewicz at its origin level, and its entry side in the spine. Results The artery of Adamkiewicz was detected in 71 (82.5%) examinations. The origin level was identified between the 9th and 11th thoracic vertebrae (T9 and T11) in 56 (79.2%) patients. In 65 (91.5%) patients, the artery was on the left side. The identification of the artery of Adamkiewicz using MCTA showed high reproducibility. Conclusions Our results were consistent with the literature regarding the identification of the artery of Adamkiewicz using MCTA, suggesting that this technique should be considered as an option to recognize this structure. In addition, we found that the distribution of the artery of Adamkiewicz in the Brazilian population is similar to that of other populations, that is, its most common origin is at the left side, between the 8th and 12th thoracic vertebrae (T8-T12).

Ultrasonographic evaluation of Achilles tendon repair after percutaneous sectioning for the correction of congenital clubfoot residual equinus.

BACKGROUND: Most cases of congenital clubfoot treated with the Ponseti technique require percutaneous Achilles tenotomy to correct the residual equinus. Clinical evidence suggests that complete healing occurs between the cut tendon stumps, but there have not yet been any detailed studies investigating this reparative process. This study was performed to assess Achilles tendon repair after percutaneous section to correct the residual equinus of clubfoot treated with the Ponseti method. METHOD: A prospective study analyzed 37 tenotomies in 26 patients with congenital clubfoot treated with the Ponseti technique, with a minimum follow-up of 1 year after the section. The tenotomy was performed percutaneously with a large-bore needle bevel with patient sedation and local anesthesia. Ultrasonographic scanning was performed after section to ascertain that the tenotomy had been completed and to measure the stump separation. In the follow-up period, the reparative process was followed ultrasonographically and assessed at 3 weeks, 6 months, and 1 year posttenotomy. RESULTS: The ultrasonography performed immediately after the procedure showed that in some cases, residual strands between the tendon ends persisted, and these were completely sectioned under ultrasound control. A mean retraction of 5.65 mm+/-2.26 mm (range, 2.3 to 11.0 mm) between tendon stumps after section was observed. Unusual bleeding occurred in one case and was controlled by digital pressure, with no interference with the final treatment. After 3 weeks, ultrasonography showed tendon repair with the tendon gap filled with irregular hypoechoic tissue, and also with transmission of muscle motion to the heel. Six months after tenotomy, there was structural filling with a fibrillar aspect, mild or moderate hypoechogenicity, and tendon scar thickening when compared with a normal tendon. One year after tenotomy, ultrasound showed a fibrillar structure and echogenicity at the repair site that was similar to a normal tendon, but with persistent tendon scarring thickness. CONCLUSIONS: There is a fast reparative process after Achilles tendon percutaneous section that reestablishes continuity between stumps. The reparative tissue evolved to tendon tissue with a normal ultrasonographic appearance except for mild thickening, suggesting a predominantly intrinsic repair mechanism.

A Novel Classification System for Slipped Capital Femoral Epiphysis Based on the Radiographic Relationship of the Epiphyseal Tubercle and the Metaphyseal Socket.

Recent studies have suggested that the epiphyseal tubercle serves as a fulcrum for rotation in slipped capital femoral epiphysis (SCFE). However, radiographic evidence of the rotational mechanism is limited. In this study, we describe a novel radiographic staging system for SCFE based on the anatomic relationship between the epiphyseal tubercle and the metaphyseal socket. METHODS: We reviewed the cases of 469 patients with SCFE who were treated at our institution between 2000 and 2017. SCFE was classified according to our proposed staging system using the preoperative lateral radiograph. Normal hips were considered to be Stage 0. In Stage 1, the tubercle is concentric within its metaphyseal socket, which is enlarged and may present peritubercle radiolucency. In Stage 2, there is evidence of eccentricity of the tubercle, which remains in contact with the posterior wall of the socket. In Stage 3, the tubercle and metaphyseal lucency reach the posterior cortex of the femoral neck. A complete dislodgment of the tubercle from the metaphysis is present in Stage 4. Intra- and interobserver agreement, and correlations between the staging system and the traditional classifications of severity, stability, and chronicity, were estimated. RESULTS: The distribution by stage was as follows: 2% of the hips were classified as Stage 0, 19% were Stage 1, 48% were Stage 2, 15% were Stage 3, and 16% were Stage 4. The staging system had excellent intraobserver (κ = 0.89 [95% confidence interval (CI) = 0.83 to 0.96]) and interobserver agreement (κ = 0.87 [95% CI = 0.72 to 1.00]). There was a high correlation between the staging system and SCFE severity as assessed by the Southwick angle (r = 0.77 [95% CI = 0.73 to 0.82]; p < 0.001). There was a moderate correlation between the staging system and the Loder classification of stability (r = 0.55 [95% CI = 0.48 to 0.62]; p < 0.001) and a negligible correlation with the classification of chronicity (r = 0.19 [95% CI = 0.10 to 0.28]; p < 0.001). CONCLUSIONS: The proposed staging system for SCFE is highly reliable and correlates well with the severity of SCFE based on the degree of displacement, with moderate correlation shown for stability. This new staging system helps in understanding the rotational mechanism of SCFE, warranting further investigation to determine its clinical application. CLINICAL RELEVANCE: The novel classification has the potential for the identification of hips that demonstrate subtle SCFE or are at pre-slip stage, or those at risk for osteonecrosis of the femoral head, failure of fixation, or slip progression.

Relative contribution of epiphyseal tubercle and peripheral cupping to capital femoral epiphysis stability during daily activities.

Epiphyseal tubercle and peripheral cupping can influence the development of slipped capital femoral epiphysis (SCFE) and Cam morphology. During normal skeletal growth, epiphyseal tubercle shrinks while the peripheral cupping grows. We hypothesized that epiphyseal tubercle act as the primary stabilizer of the head-neck junction at early stages and this role is gradually transferred to epiphyseal cupping as the tubercle shrinks and cupping grows. From a cohort of 80 boys and girls (8-15 years old) with normal hips, CT scans of 5 subjects corresponding to minimum, 25th percentile, median, 75th percentile and maximum relative tubercle and cupping height were used to develop 3D finite element models. In vivo measured hip loads were used to study load sharing between the tubercle and peripheral cupping under combined and uniaxial loads exerted on femoral head during a range of daily activities. Lower epiphyseal tubercle height, larger epiphyseal cupping height and bigger differences in tubercle and cupping heights were strongly associated with increased epiphyseal cupping to epiphyseal tubercle stress ratios (R2 > 0.7). We found lower peripheral cupping stresses relative to the tubercle (cupping to tubercle stress ratio <1) in hips with larger tubercle and smaller cupping. The relative decreases in tubercle size along with increased in peripheral cupping in our models gradually shifted the load distribution to higher stresses in the periphery compared to the epiphyseal tubercle area (cupping to tubercle stress ratio >1). Both tubercle and cupping play a substantial role in sharing the generated stresses across the head-neck junction under all tested loading conditions. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1571-1579, 2019.

Predicting Risk of Contralateral Slip in Unilateral Slipped Capital Femoral Epiphysis: Posterior Epiphyseal Tilt Increases and Superior Epiphyseal Extension Reduces Risk.

BACKGROUND: Femoral morphology may influence the etiology of slipped capital femoral epiphysis (SCFE). We investigated whether radiographic parameters of femoral head-neck morphology are associated with a subsequent contralateral slip in patients presenting with unilateral SCFE. METHODS: We evaluated 318 patients treated for unilateral SCFE between 2000 and 2017. There were 145 males (46%), and the mean age in the series was 12.4 ± 1.7 years. The patients were followed for a minimum of 18 months or until the development of a contralateral slip (70 patients, 22%). We measured the epiphyseal tilt, epiphyseal extension ratio, alpha angle, and epiphyseal angle of the uninvolved, contralateral hip at initial presentation. Multivariable logistic regression analysis was used to assess whether femoral measurements were associated with the occurrence of a contralateral slip. Receiver operating characteristic (ROC) curves were used to determine optimal thresholds of radiographic measures to determine an increased risk of a contralateral slip. A number-needed-to-treat (NNT) analysis was conducted to evaluate the effectiveness of the femoral measurement thresholds in preventing a contralateral slip. RESULTS: Multivariable analysis, controlling for triradiate cartilage status, identified the lateral tilt angle and the superior epiphyseal extension ratio as independent factors associated with the likelihood of a contralateral slip. For each additional degree of posterior tilt, the odds of a contralateral slip increase by 8% (odds ratio [OR] = 1.08; 95% confidence interval [CI] = 1.02 to 1.14; p = 0.008), and for each 0.01 increase in the superior epiphyseal extension ratio, the odds of a contralateral slip decrease by 6% (OR = 0.94; 95% CI = 0.88 to 0.99; p = 0.03). A threshold for the epiphyseal tilt of 10° corresponded to a predicted probability of a contralateral slip of 54% in patients with open triradiate cartilage and an NNT of 3.3. CONCLUSIONS: In patients presenting with unilateral SCFE, a higher posterior tilt of the epiphysis increases the risk while an increased superior extension of the epiphysis reduces the risk of a contralateral slip. Our findings may assist the discussion about contralateral prophylactic pinning in patients with unilateral SCFE. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

A Technique for Dynamic Cervical Magnetic Resonance Imaging Applied to Cervical Spondylotic Myelopathy: A Reliability Study.

STUDY DESIGN: Cross-sectional study. OBJECTIVE: To evaluate morphometric variations of the cervical spine in patients with cervical spondylotic myelopathy (CSM) using a standard technique of dynamic magnetic resonance imaging (MRI), to assess the inter- and intraobserver reliability of measurements of morphometric parameters based on this imaging, and to compare the resulting measurements with those previously published. SUMMARY OF BACKGROUND DATA: Because dynamic factors may contribute to the etiology and severity of CSM, dynamic (flexion-extension) MRI may be useful to better evaluate for spinal stenosis and cord compromise. METHODS: Dynamic cervical MRI was obtained using a standard protocol with the neck in neutral, flexion, and extension positions. The morphometric parameters considered were anterior length of the spinal cord (ALSC), posterior length of the spinal cord (PLSC), spinal canal diameter, and spinal cord width. Two observers analyzed the parameters independently, and the inter- and intraobserver reliabilities were assessed by the intraclass correlation coefficient (ICC). RESULTS: A total of 18 patients were included in the study and all completed the dynamic MRI acquisition protocol. The inter- and intraobserver reliabilities demonstrated "almost perfect agreement" (ICC >0.9, P < 0.001) for ALSC and PLSC in all positions. The spinal canal diameter had inter- and intraobserver reliability classified as "almost perfect agreement" (ICC: 0.83-0.98, P < 0.001 and ICC: 0.90-0.99, P < 0.001, respectively) in all positions. The spinal cord width had inter- and intraobserver reliability classified as "substantial agreement" (ICC: 0.73-0.94, P < 0.001 and ICC: 0.79-0.96, P < 0.001, respectively) in all positions. ALSC and PLSC in neutral, flexion, and extension positions from the present study were significantly greater compared to the measurements previously published (P < 0.001). CONCLUSION: The dynamic MRI protocol presented was safe and may allow a more complete evaluation of variations in the cervical spine in patients with CSM than traditional MRI protocols. The morphometric parameters based on this protocol demonstrated excellent inter- and intraobserver reliabilities. LEVEL OF EVIDENCE: 4.