Radiocapitellar Line Research Articles

Comprehensive Analysis of Pediatric Elbow Radiographic Lines and Angles.

The study aimed to determine relevant radiographic lines and angles of children's elbow. A retrospective cross-sectional study. Tertiary pediatric trauma center. X-rays of healthy children's elbows 0-18 years of age in whom the radiographic image of the elbow in 2 projections was read without signs of fracture and possible indirect signs of fracture, whereas the exclusion criterion was a clearly visible poor image projection. Gender, age [patients were divided into 6 groups-group 1 (0-3 years), group 2 (4-6 years), group 3 (7-9 years), group 4 (10-12 years), group 5 (13-15 years), group 6 (16-18 years)], side, intersection of the radiocapitellar line in the anteroposterior (AP) projection, intersection of the radiocapitellar line in the lateral projection, intersection of the anterior humeral line, Baumann angle, carrying angle, lateral capitellohumeral angle, shaft condylar angle, intersection of the coronoid line and radioulnar overlap. Two hundred elbows were evaluated. The radiocapitellar line in AP and lateral projections passed through the middle third of the capitellum in 74.5% and 93%, respectively. The anterior humeral line passed through the middle third of the capitellum in 88.5% of cases. When observing the proportion of radiocapitellar lines passing through the middle third of the capitellum in the AP, with increasing age an increasing proportion of lines pass through the middle third of the capitellum [from 8.3% in group 1 (0-3 years) to 94.1% in group 6 (16-18 years), P = 0.001] and lateral projection (from 50% in group 1%-100% in group 6, P = 0.023) and anterior humeral line (from 25% in group 1%-100% in group 6, P = 0.0001). The mean Baumman angle, carrying angle, lateral capitellohumeral angle, shaft condylar angle were 71.59 degrees, 10.97 degrees, 50.84 degrees, and 55.31 degrees, respectively. With age, the shaft condylar angle records the greatest increase (from 41.6 degrees in group 1-68.2 degrees in group 6, P = 0.000). A correlation was observed between Baumann angle and carrying angle (r = -0.674) and between Baumann angle and radioulnar overlap (r = 0.542). Considering the anatomical variability of children's elbow, radiologic measurements and their interpretation, in the context of timely diagnostics, must be approached with great caution, especially in younger age groups, because it is with them that the largest proportion of lines and angles do not follow established principles. Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

A Rare Case:Transphyseal Distal Humerus Fracture in a Newborn.

Transphyseal fractures of the distal humerus are usually seen in children younger than 3 years of age and are considered as Salter-Harris Type I epiphysiolysis. Neonatal transphyseal distal humerus injuries are extremely rare. It usually occurs due to trauma during difficult labour but can also be seen after child abuse. Since the distal humerus is composed of cartilaginous tissue in newborns, it is difficult to make a diagnosis with direct radiography. Patients are often diagnosed with elbow dislocation. However, elbow dislocation is almost never seen under the age of 3 years. Transphyseal fractures can be seen as a result of manoeuvres performed to deliver the baby during difficult normal delivery. Transphyseal humeral injuries can also be seen after caesarean section, child abuse and falling on the hyperextended arm. Clinical symptoms include pain, swelling, ecchymosis and crepitation at the elbow. Pseudoparalysis is present due to pain. In children with a history of difficult birth or trauma, evaluation with direct radiography should be performed initially. Radiocapitellar line is distorted on radiographs and the elbow joint appears subluxated. The treatment algorithm for transfusional humeral fractures in neonates is varied. It should be remembered that patients in this age group have a tremendous healing capacity. In conservative treatment, 2-4 weeks of follow-up with a long-arm splint after reduction is sufficient. In addition, closed reduction-internal fixation or open reduction-internal fixation can be applied according to the amount of displacement of the fracture. Cubitus varus, osteonecrosis, growth disturbance, decreased range of motion, compartment syndrome, neurovascular injury and infection are the main complications seen after transfusional humeral fractures.

A Comparative Study of the Modified Baumann's Angle Between the Dominant and Non-Dominant Sides in a North Indian Pediatric Population.

Background The literature points towards the fact that paediatric elbow fractures happen more frequently and have greater variability when contrasted with adults. Between 65%-75% of pediatric fractures involve the upper extremity, and supracondylar humerus is the most common of them all. To know the exact site of injury and to estimate the degree of reduction after manipulation, the modified Baumann's angle, the Baumann's angle, the Humero-condylar angle, the Anterior humeral line, and the Radio-capitellar line are the parameters most commonly used. This study was carried out to compare the modified Baumann's angle between both upper limbs in the paediatric population. Methodology This cross-sectional study was conducted in a tertiary health care centre in Northern India for one year from September 1, 2021, to August 31, 2022. We included pediatric patients in the age group of 3-16 years. Age, sex, weight, height, BMI, secondary sexual characters, and handedness were noted in all the children enrolled in our study. In both the dominant and non-dominant sides, the mean arm length, the forearm length, the inter-epicondylar distance, the clinical carrying angle, the radiological carrying angle, and the modified Baumann's angle were calculated. Results A total of 113 children were enrolled in the study. The majority of children (71.7%) had dominance on the right side. In both the dominant side and non-dominant side, mean arm length, forearm length, inter-epicondylar distance, clinical carrying angle, radiological carrying angle, and modified Baumann's angle values were calculated. On evaluating the data statistically, a significant difference between the two sides was observed for all the parameters (p<0.05), except forearm length (p-value -0.954). Multivariate analysis showed that only BMI was significantly negatively associated with modified Baumann's angle (p=0.016), and only age (0.019) and BMI (<0.001) were found to be significantly associated with the difference in modified Baumann's angle. Conclusions The findings of this study will be helpful in the management of elbow disorders and their reconstruction following trauma. A significant difference was found in the modified Baumann's angle between dominant and non-dominant sides, and it also showed a negative significant correlation with arm length, forearm length,and the presence of secondary sexual characteristics. The equations derived in this study will be helpful in the simple derivation of the modified Baumann's angle and its differencefrom simple measurements of the upper limb parameters.

Çekilmiş Dirsek Sendromunda Radyolojik Analizin Gerekliliğinin İncelenmesi

Objective: Primary objective was to reveal the necessity of radiological analysis by investigating the differences in radiological findings in the pulled and intact sides of pulled elbow patients. The secondary goal was to examine pulled elbow patients' demographic and radiographic distributions to reveal recurrence-related risk factors.&#x0D; Materials and Methods: In this retrospective prognostic study, 80 patients, treated for pulled elbow between August 2019 and January 2022 were examined. The patient's gender, age, side, and injury mechanism information were evaluated. The radio-capitellar line, the radial epiphyseal angle, and the humero-ulnar angle were evaluated on both injured and intact side X-rays. &#x0D; Results: No missed fractures were detected, and no significant difference was found between injured and intact sides in the radiological analysis (p&gt;0.05). Recurrent dislocations were detected in 14 patients (17.5%). No significant relationship was found between recurrent pulled elbow and gender, side, mechanism of injury, and radiological findings (p&gt;0.05). &#x0D; Conclusion: Although radiographic examination of the pulled elbow is not diagnostically and prognostically necessary, radiographs of the elbow can be taken and examined regarding fracture exclusion and medicolegal concerns. There is no obvious risk factor predicting recurrent dislocation.

Ultrasound imaging in diagnostics of Monteggia lesion in children.

Purpose:The aim of the study is to evaluate the use of ultrasound imaging in diagnostics of Monteggia lesion in children where conventional radiographs and the use of the radiocapitellar line fail to provide an accurate diagnosis.Methods:Prospective diagnostic study of 70 patients treated between May 2018 and July 2021 in a pediatric level 1 trauma center. In 20 patients with the confirmed radiographic diagnosis of Monteggia lesion, an ultrasound of the humeroradial joint was performed to determine signs of both normal and dislocated elbow joint. In 36 patients with suspected humeroradial dislocation on plain radiographs, ultrasound imaging was performed to determine the definitive diagnosis. Overall, 14 patients with elbow joint injury other than humeroradial dislocation were excluded from the study.Results:The “double-hump sign” and the “congruency sign” were determined as normal findings on ultrasound of the humeroradial joint. These signs were applied to patients with unclear findings on radiographs. In three patients, the dislocation of the humeroradial joint was confirmed by ultrasound. In two patients, “defect in congruency sign” was seen during reduction despite normal radiographs, which required re-reduction. In 31 patients, dislocation of the humeroradial joint was refuted. In 34 out of the 36 patients, the diagnosis determined by ultrasound was confirmed in follow-up. Two patients did not attend the follow-up examination.Conclusion:Ultrasound imaging is an accessible, non-invasive, and dynamic point-of-care method that can be applied in children suffering from suspected humeroradial dislocation and/or subluxation.Level of evidence:Level III—diagnostic study.

Using the radiocoronoid line for diagnosis of elbow dislocation.

The radiocapitellar line (RCL) has been widely used to diagnose elbow dislocation. However, there are limitations to the RCL, with the cartilaginous portion of bone making interpretation of radiographs difficult. The study aims to show that the radiocoronoid line, which connects two points on the medial aspect of the radius, proximal to the radial tuberosity, is more suited to diagnose elbow dislocations in the anterior-posterior projection. This study also observes factors affecting accuracy of the radiocapitellar line. The radiographs of 50 normal and 17 laterally dislocated elbows were obtained. An unbiased independent reviewer drew the radiocoronoid and radiocapitellar line (RCL). Four other blinded independent reviewers drew the RCL and the radiocoronoid line for 20 radiographs and repeated the process a week later. The accuracy of the RCL was assessed using distance away from bisection point of capitellum, and ratio (distance from the point where line crosses capitellum to lateral aspect of capitellum over the total width of capitellum). The relationship of the radio-coronoid line and the lateral aspect of coronoid fossa was assessed, with dislocation being the line lateral to it and normal being medial to or on it. The radiocoronoid line had a higher accuracy (95.5%) compared to RCL (32.8%), higher specificity (94%) compared to RCL (10%) as well as higher positive predictive value (85%) compared to RCL (27.4%). There was no intra- or inter-observer variability for the radio-coronoid line. Skeletal age statistically predicted the ratio for the male population ( P < 0.05), however, the independent variables did not statistically predict the dependent variables for the female and total population. The radiocoronoid line serves as an additional method to assess radiocapitellar joint lateral dislocation. It is more accurate and reliable than the radiocapitellar line in the anterior-posterior projection. Sex and skeletal age also influence the accuracy of the radiocapitellar line with the radiocapitellar line nearing the bisection point as skeletal age in males increases.

Outcomes of Treatment of Monteggia Fractures with Reduction and Internal Titanium Elastic Nail Fixation of the Ulna.

The purpose of this paper is to evaluate the usefulness of radiographic indices of humero-radial joint instability in order to predict treatment outcomes in Monteggia fractures. A retrospective analysis was conducted in a group of patients who underwent closed reduction and internal titanium elastic nail (TEN) fixation of the ulna and closed reduction of a dislocation of the radial head between 2016 and 2018. The indications for intrame-dullary fixation comprised transverse or short oblique fractures. The direction of the dislocation was classified according to Bado. The following radiographic indies were assessed: Radiocapitellar Line, Lateral Humeral Line, Proximity Index, and Radial Head Displacement Index. Treatment outcomes were assessed with the Oxford Elbow Score and Mayo Elbow Performance Score, and com-plications were assessed with a modified Clavien-Dindo-Sink scale. No coincidence between poor functional and radio-graphic outcomes was demonstrated. 1. Regardless of the severity of the injury, eligibility for surgery and correctly performed surgical treatment guarantee a good final outcome. 2. Patients treated with TEN regain their preoperative mobility. 3. There was no coincidence between poor functional and radiographic outcomes, except for one patient in whom subluxation of the radial head persisted despite surgery and was confirmed radiographically and functionally. 4. It would be beneficial for clinical practice to introduce simple, reproducible radiographic parameters for unambiguous assessment of the effectiveness of treatment and predicting treatment outcomes; unfortunately none of the parameters we investigated were sufficiently reliable. 5. The radiographic parameters analysed in this paper are dependent on the quality of the radiological examinations performed.

Growth of the capitellar ossification center and its relationship within the lateral condyle of the distal humerus in skeletally immature elbows: a study using MR images

To more accurately interpret the anterior humeral and radiocapitellar lines on simple radiographs of pediatric elbow, we investigated age-related changes of the capitellar ossific nucleus (CON) by using MRIs. Elbow MRIs from 79 children aged 1-16 years and free from demonstrable lesions in the distal humerus were retrospectively reviewed. On coronal images, the distal cartilaginous vertex of the capitellum, which articulates with the center of the radial head, was situated about 15%p laterally from the center of CON regardless of age. On sagittal images, the anterior humeral line passed the center of CON in older children (>6 years), but passed anteriorly in children with an age ≤6 years. Also on sagittal images, the anterior cartilaginous vertex of the capitellum was positioned within 10% of the level of the center of CON in all age groups. Recognition of the capitellar ossification pattern within the lateral condyle would aid in more accurate assessment of pediatric elbows on simple radiographs. Based on the results of the present MRI study, the following points were identified for the interpretation of simple radiographs: (1) The radiocapitellar line on anteroposterior views intersects the CON by about 15%p laterally regardless of age; (2) The anterior humeral line on lateral views intersects the center of the CON in older children, but passes anteriorly in younger (≤6 years) children; and (3) The radiocapitellar line on lateral radiographs invariably passes the center of CON regardless of the age.

An Alternative to the Traditional Radiocapitellar Line for Pediatric Forearm Radiograph Assessment in Monteggia Fracture.

To find a new reference for assessment of pediatric forearm radiographs besides the traditional RCL. RCLs were drawn on the anteroposterior (AP) and lateral radiographs of 170 normal pediatric forearms. Three lines were drawn on each radiograph: the first was drawn along the longitudinal center of the radial neck (N-line); the second, along the radial shaft (S-line); and the third, through the midpoints of the proximal and distal radial physes (P-line). The P-line was least likely to miss the capitellum on both AP views and lateral views, and the P-line most frequently passed through the central third of the capitellum on both AP views and lateral views. Our proposed radiocapitellar P-line was found to be much more reliable in younger children than traditional RCLs.

Missed Pediatric Monteggia Fractures.

* Careful scrutiny of radiographs is important in the assessment of pediatric elbow injuries. Disruption of the radiocapitellar line and an increased bow of the posterior ulnar border are sometimes subtle signs of a Monteggia injury.* An attempt at closed reduction up to 4 weeks after injury has been cited in the literature as successfully treating some missed injuries.* Operative reduction of chronic radial-head dislocation provides good to excellent range of motion and functional outcome in the setting of irreducible chronic radial-head dislocation.* Ulnar osteotomy and correction of the ulnar deformity component of the missed Monteggia injury are the key to indirect anatomic reduction of the radiocapitellar joint.* Supplemental procedures aimed at increasing the stability of the radiocapitellar joint (e.g., annular ligament reconstruction, radiocapitellar Kirschner wire fixation, radioulnar Kirschner wire fixation) should be directed by a thorough assessment of radiocapitellar stability following ulnar osteotomy and correction of the ulnar deformity.

A Retrospective Study Comparing Crossed and Lateral Wire Configurations in Paediatric Supracondylar Fractures.

Background:Supracondylar fractures are common in children and are associated with significant morbidity.The purpose of our study was to assess and compare the clinical and radiological outcome of management of supracondylar fractures by both wire configurations, along with identifying factors that predispose to complications.Materials & Methods:We retrospectively reviewed all paediatric cases admitted with a supracondylar fracture over a five year period. We reviewed case notes, theatre records and radiographs to determine the age of the patient, classification of fracture, treatment method, delay to theatre, duration of surgery, wire configuration, Baumann´s angle, radiocapitellar alignment, anterior humeral alignment and complications.Results:During the five year period we admitted 132 patients and complete notes were available for 123 patients for analyses. For all the patients managed with wire stabilisation 23% developed complications, including 13% with significant complications including nerve injuries and fracture displacements. All five nerve injuries had crossed wires, whereas all for fracture displacements had lateral wires. Baumann´s angle was 76.7 degrees in the group with no complication and 72.2 degrees in the significant complication group (p=0.02). Radiocapitellar line and anterior humeral line were not satisfactory in 5% and 15% of the group with no complications, and 17% and 33% of the group with significant complications.Conclusion:We found more complications in lateral pinning configurations, although all nerve injuries were in patients with crossed wire configurations. The factors we believe are associated with a higher likelihood of complications are inadequate post-operative radiological appearance.

Significance of the Lateral Humeral Line for Evaluating Radiocapitellar Alignment in Children.

The radiocapitellar line (RCL) was originally described for evaluation of the alignment of the RC joint on lateral images of the elbow. Although, many authors have translated the utilization of RCL into coronal imaging, previous studies have not been performed to confirm validity. The purpose of this paper was to identify an accurate way of evaluating pediatric RC alignment in the coronal plane. Thirty-seven anteroposterior (AP) radiographs of 37 children were evaluated to determine the position of the RC joint in the coronal plane. All had acceptable magnetic resonance imaging (MRI) studies available for comparison. The lateral humeral line (LHL), consisting of a line along the lateral edge of the ossified condyle of the distal humerus parallel to the axis of the distal humeral shaft, was studied as it related to the lateral cortex of the radial neck. Three children with a confirmed diagnosis of a Bado III, lateral displaced radius, Monteggia fracture were also evaluated. The LHL passed along the edge of or lateral to the radial neck on all AP radiographs and all MRI studies. The RCL failed to intersect the capitellum on 2 AP radiographs. On MRI, the RCL also passed lateral to the capitellar ossification center in 3 patients. In addition, the RCL was seen passing through the capitellum at a mean of the lateral 30% (range, 0% to 64%) on AP radiographs and 26% (range, 0% to 48%) on MRI. For all 3 children with a Bado III Monteggia fracture, the LHL crossed the radial neck and the RCL did not intersect the capitellum. The RCL can fail to intersect the capitellar ossification center on AP radiographs and MRI in pediatric elbows without injury. The LHL consistently lies lateral to the radial neck in normal elbows and medial to the lateral aspect of the radial neck on all Bado III fracture-dislocations. It, therefore, can be used as an adjunct in evaluating the RC joint on AP imaging. The RCL most commonly intersects the lateral one third of the ossification center on both plain radiographs and MRIs. Level III-diagnostic.

Eccentric rule of the radiocapitellar line from radiographs of normal elbows in young children.

Eccentric rule of the radiocapitellar line from radiographs of normal elbows in young children.

Eccentric Capitellar Ossification Limits the Utility of the Radiocapitellar Line in Young Children.

The radiocapitellar line (RCL) has long been used for the radiographic evaluation of elbow alignment. In children, the capitellar ossific nucleus serves as a proxy for the entire capitellum, but this substitution has not been verified. Using magnetic resonance imaging (MRI), we sought to understand how maturation of the ossific nucleus of the capitellum affects the utility of RCL throughout skeletal maturation of the elbow. The RCL was drawn on coronal and sagittal MRIs in 82 children (43 boys, 39 girls; age range, 1 to 13 y) with at least 3 patients in each 1-year interval age group. The perpendicular distance of the RCL from the center of both the cartilaginous capitellum and the capitellar ossific nucleus was measured relative to its total width, and a percent offset for each measurement was calculated. Logarithmic regression analysis was performed to analyze the effect of age and sex on percent offset. The RCL reliably intersected with the central third of the cartilaginous capitellum at all ages in both planes. Although the RCL intersected with the ossified capitellum in all but 3 measurements, it intersected with the central third of the ossified capitellum less often in younger children in both sagittal (B=0.47, P<0.001) and coronal (B=0.31, P=0.002) planes. Percent offset decreased significantly with age in a logarithmic manner in both sagittal (r=0.57, P<0.001) and coronal (r=-0.47, P<0.001) planes. 95% confidence intervals predict that the sagittal plane RCL will accurately intersect the central third of the ossified capitellum by age 10 years in girls and age 11 years in boys but not in the coronal plane. Eccentric ossification of the capitellum explains RCL variability in young children. The RCL does not reliably intersect the central third of the ossified capitellum until ages 10 years in girls and 11 years in boys in the sagittal plane. The RCL should be used within its limitations in skeletally immature children and should be combined with advanced imaging if necessary.

Children’s orthopaedics

The February 2015 Children’s orthopaedics Roundup360 looks at: Hip dislocation in children with CTEV: two decades of experience; Population-based prevention of DDH in cerebral palsy: 20 years’ experience; Shoulder derotation in congenital plexus palsy; Back pain in the paediatric population: could MRI be the answer?; Intercondylar fracture of the humerus in children; The Dunn osteotomy in SUFE; Radiocapitellar line a myth!; Do ‘flatfooted’ children suffer?

A line drawn along the radial shaft misses the capitellum in 16% of radiographs of normal elbows.

The radiocapitellar line (RCL) is a routinely referenced radiographic measurement for evaluating injury of the pediatric elbow, such as a Monteggia fracture. It is most commonly described as a line drawn along the radius that should intercept the center of the capitellum in a normal elbow. However, the RCL has not been rigorously defined or validated in young children. The RCL was drawn out on the anteroposterior and lateral radiographs of 116 normal pediatric elbows by 3 examiners. On each radiograph, lines were drawn along the longitudinal center of the radial neck as well as the radial shaft. The distance from each of these lines to the center of the capitellum was defined as the line-capitellar distance (LCD). The LCD was standardized to the patient size and correlated with patient variables. Of the 2052 RCLs drawn, 50% (1029/2052) fell outside the middle third of the capitellum and 8.6% (176/2052) missed the capitellum completely. Lines drawn along the radial neck in the anteroposterior and lateral views missed the capitellum less frequently (1.2% vs. 12.7%, P<0.0001) and passed through its central third less (77.8% vs. 44.7%, P<0.0001) when compared with lines drawn using the radial shaft. Lines along the radial neck intersected the capitellum significantly more often on the lateral view than on the anteroposterior view (98.8% vs. 96.8%, P=0.06) and were more likely to pass through the center third of the capitellum (77.8% vs. 55.5%, P<0.0001). With both techniques of drawing the RCL, the percent of measurements falling within the middle third of the capitellum was higher in patients above 5 years of age (P<0.001). The RCL is more reliable in older patients and shows considerable variation in infants. The RCL does not invariably bisect or fall within the middle third of the capitellum in normal pediatric elbows. Therefore, an abnormal RCL is suggestive but not pathognomonic for injury such as Monteggia fracture. An RCL drawn along the radial shaft will miss the capitellum in 15.6% of elbows. The most consistent RCL is drawn along the radial neck on the lateral view. Patient variables such as age and sex should be considered in the ability of the RCL to identify elbow injury. Diagnostic Level 3.

Absence of Radiographic Abnormalities in Nursemaid’s Elbows

Disagreement exists between physicians on the usefulness of a prereduction radiograph for diagnosis and treatment of nursemaid's elbows in children. Some evidence suggests that nursemaid's elbows have identifying features on radiographs. This study compares the radiographs of nursemaid's elbows to normal, control elbows in children and hypothesizes that differentiating features do not exist on radiograph. For this retrospective case-control study, hospital billing records were searched to identify all patients under age 6 treated with closed reduction for a nursemaid's elbow between November 2005 and October 2009. Twenty-seven nursemaid's elbows were age-matched and sex-matched to 27 normal "comparison view," control elbows. Radiocapitellar line offset, proximal radial length, anterior fat pad angle, and visibility of the posterior fat pad were measured on the radiographs by 2 raters. Their interrater reliability was assessed with intraclass correlations, and the nursemaid's and control elbow measures were compared using Wilcoxon tests. Nursemaid's elbows and healthy control elbows did not differ significantly in offset of the radiocapitellar line from the capitellum center on anteroposterior (P=0.49) or lateral views (P=0.67), in proximal radial length (P=0.95), anterior fat pad angle (P=0.49), or posterior fat pad visibility (P=1.00) on lateral views. Nursemaid's elbows are indistinguishable from healthy elbows on radiograph. Thus, the term "radial head subluxation" appears to be a misnomer, and prereduction radiographs should only be used to eliminate the possibility of fracture. From a radiologic perspective, nursemaid's elbows remain a diagnosis of exclusion. Therapeutic Level III-retrospective comparative study.

Limitations of the Radiocapitellar Line for Assessment of Pediatric Elbow Radiographs

The radiocapitellar line (RCL) is recommended for evaluating radiocapitellar alignment in skeletally immature elbows, yet its parameters have not been clearly defined. This study systematically assesses the RCL relationship in normal elbows, investigating the impacts of radiographic view, choice of anatomic landmarks, patient age, forearm position, and observer bias on the manner in which the RCL intersects the capitellum. On radiographs of 20 normal elbows (age range, 1 to 8 y), 3 pediatric orthopaedic surgeons, blinded to clinical history, drew lines (RCLs) on anteroposterior and lateral projections, along the radial shaft and neck, and with and without the capitellum visible. Line placement was repeated 2 weeks later. The relationship of each RCL to the capitellum was assessed continuously using the perpendicular distance to the center of the capitellum, normalized to capitellar width [line-capitellar distance (LCD)], and categorically as passing through the middle third, outer two-thirds, or outside the capitellum. Of the 480 RCLs drawn, 23 (5%) missed the capitellum and 224 (47%) missed the middle third. More radial neck than shaft lines intersected the middle third on both anteroposterior and lateral views (P < 0.05, Fisher exact test), with the lowest LCD values for neck lines on the lateral view (P < 0.05, analysis of variance (ANOVA)). More RCLs intersected the middle third when the capitellum was visible than when it was obscured (P = 0.03, Fisher exact test), suggesting an effect of observer bias. Patient age correlated inversely with LCD (P < 0.001). The angle between the neck and shaft lines correlated positively with LCD (P < 0.001), suggesting an impact of forearm rotation position. Intraobserver and interobserver reliability was moderate-to-substantial (κ = 0.40-0.75). The RCL best defines normal radiocapitellar alignment when the line is drawn along the radial neck on the lateral view, although this relationship is affected by bias, patient age, and forearm rotation position. The RCL does not reliably intersect the middle third of the capitellum, arguing against its sufficiency for assessing precise radiocapitellar alignment. Diagnostic Level 3.

Tardy Displacement of Traumatic Radial Head Dislocation in Childhood

The diagnosis of traumatic dislocation of the radial head, either isolated or as part of a Monteggia fracture-dislocation, was delayed in 10 of the 110 children treated with these injuries during the study period. In eight children, the dislocation was overlooked on the initial radiographs. In two children, the radial head was reduced on the initial elbow radiographs, but it was dislocated 10 days later in one child and 21 days later in the other. The most likely explanation is that the radial head dislocated at the time of impact, spontaneously reduced by the time the first radiographs were obtained, and redislocated while the arm was in a cast. We conclude that radiographic assessments of the radiocapitellar joint, by using the radiocapitellar line, are required in children with elbow and forearm injuries at presentation and when the cast is removed.

Radiographic changes with radial head subluxation in children

Radial head subluxation (RHS) produces no radiographic abnormalities according to most experts. However, recent anecdotal case reports have identified displacement of the radiocapitellar line (RCL) in pediatric patients with RHS. To verify this finding, we retrospectively reviewed all patients less than 5 years of age who received elbow and forearm radiographs in our emergency department. From January 1988 through April 1989, we identified 20 cases of RHS. Of the 20 radiographs, 5 (25%) were read by the attending radiologist as abnormal due to RCL displacement indicating subluxation of the radiocapitellar articulation. All 5 of these radiographs had RCL displacement greater than 3 mm. The remaining normal radiographs had RCL displacement less than or equal to 3 mm. The presence of RCL displacement without disruption of the radiocapitellar articulation confirms the diagnosis of RHS, but does not appear to change treatment or outcome in this subset of patients. In addition, radiographs may not be mandatory when the diagnosis of RHS is certain. We suggest obtaining radiographs if the history (i.e., fall) or physical examination is atypical or if reduction is unsuccessful to rule out more serious injuries such as radial head dislocation or fracture.