J. Herman Kan

Application of 3-D printing (rapid prototyping) for creating physical models of pediatric orthopedic disorders

Three-dimensional printing called rapid prototyping, a technology that is used to create physical models based on a 3-D computer representation, is now commercially available and can be created from CT or MRI datasets. This technical innovation paper reviews the specific requirements and steps necessary to apply biomedical 3-D printing of pediatric musculoskeletal disorders. We discuss its role for the radiologist, orthopedist and patient.

Multimodality imaging of developmental dysplasia of the hip

Developmental dysplasia of the hip (DDH) is a spectrum disorder resulting in underdevelopment of the acetabulum. Radiographs and ultrasound are the mainstays for screening, with CT and MRI playing important roles in assessing outcome after treatment. The purpose of this article is to illustrate the use of multimodality imaging in the diagnosis and management of DDH.

Combined pre-injection wrist and ankle MRI protocol and steroid joint injections in juvenile idiopathic arthritis

Precise localization of affected compartments of the wrist and ankle in children with an established diagnosis of juvenile idiopathic arthritis (JIA) is clinically challenging. The purpose of this paper is to describe our experience utilizing a pre-injection MRI protocol of the wrist and ankle for localizing disease activity followed by fluoroscopically guided joint injections in children with JIA.

Wrist and Ankle MRI of Patients With Juvenile Idiopathic Arthritis: Identification of Unsuspected Multicompartmental Tenosynovitis and Arthritis

OBJECTIVE The purpose of this study was to characterize the extent of joint and tendon involvement in patients with juvenile idiopathic arthritis referred for MRI of the wrist or ankle. MATERIALS AND METHODS Forty-five patients (32 female and 13 male patients; mean age, 10 years; age range, 1-19 years) with an established diagnosis of juvenile idiopathic arthritis were referred for MRI of the wrist or ankle between January 2000 and August 2012 (39 wrists and 33 ankles). All MRI examinations and clinical notes were reviewed, and joint and tendon involvement was recorded. RESULTS Tenosynovitis was present in 50% (36/72) of examinations. Tenosynovitis was not documented in clinical notes before MRI. When tenosynovitis was present, an average of 3.5 tendons were involved (range, 1-12 tendons). For the wrist, 59% (23/39) had tenosynovitis, and the extensor digitorum tendon (23% [9/39]) was most commonly involved. For the ankle, 39% (13/33) had tenosynovitis, and the tibialis posterior tendon (33.3% [11/33]) was most commonly involved. For the wrist, 89.7% (35/39) had active joint inflammation with an average of 3.1 joints involved (range, 0-6 joints), and the intercarpal joint was most commonly involved (69% [27/39]). For the ankle, 69.7% (23/33) had active joint inflammation, with an average of 2.4 joints involved (range, 0-5 joints), and the tibiotalar joint (52% [17/33]) was most commonly involved. CONCLUSION Multicompartmental tenosynovitis and arthritis involvement is common in patients with juvenile idiopathic arthritis referred for MRI of the wrist or ankle and is underappreciated on clinical examination. International League of Associations for Rheumatology subclassification and targeted intraarticular steroid injections guided by clinical examination alone may lead to undertreatment or incorrect treatment of active disease.

Juvenile idiopathic arthritis and enthesitis-related arthropathies

Juvenile idiopathic arthritis (JIA) represents a spectrum of non-pyogenic inflammatory arthritides affecting children. The purpose of this pictorial review is to illustrate the imaging spectrum of JIA and the role of radiology in disease diagnosis and management.

MRI of Suspected Lower Extremity Musculoskeletal Infection in the Pediatric Patient: How Useful Is Bilateral Imaging?

OBJECTIVE The purpose of this study was to determine the frequency of bilateral abnormalities in children with suspected lower extremity musculoskeletal infection and the impact of detection of contralateral abnormalities by MRI on patient management. MATERIALS AND METHODS A retrospective review of 165 consecutive bilateral lower extremity MRI examinations performed for suspected musculoskeletal infection in pediatric patients (64% boys and 36% girls; mean age, 7.5 years; age range, 0-18 years) in 2010 at a childrens hospital was performed. Imaging findings were compared with the final clinical diagnosis and management. RESULTS The MRI examination was normal in 2% (4/165). Osteomyelitis was diagnosed in 33% (54/165) of the MRI examinations; among these examinations 20% (11/54) had both ipsilateral septic arthritis and osteomyelitis, 2% (1/54) had bilateral osteomyelitis, and 67% (111/165) of the examinations were negative for osteomyelitis. Bilateral abnormalities were detected in 20% (22/111) of patients without osteomyelitis, with 18% (4/22) presenting with bilateral signs or symptoms. Abnormalities in the contralateral extremity included myositis (18%, 4/22), stress reaction (18%, 4/22), subcutaneous edema (18%, 4/22), leukemia (14%, 3/22), reactive joint effusion (14%, 3/22), Baker cyst (5%, 1/22), and osteonecrosis (5%, 1/22). Identification of clinically unsuspected abnormalities of the contralateral extremity by MRI was not associated with alterations in medical or surgical management in children with or without osteomyelitis. CONCLUSION Clinically unsuspected abnormalities of the asymptomatic contralateral lower extremity are common in children referred for MRI of suspected musculoskeletal infection. However, detection of these abnormalities is not associated with alterations in patient management.

Marginal value of radiographs in the interpretation of MR images obtained for pediatric knee pain.

OBJECTIVE Radiographs are often obtained before MRI in the evaluation of pediatric knee pain, but the value of these radiographs is undefined. The purpose of this study was to determine the marginal value of knee radiographs in the interpretation of knee MR images requested by pediatric sports medicine and orthopedic subspecialists. MATERIALS AND METHODS Knee MRI examinations of 194 pediatric patients (mean age, 14 [SD, 3.1] years; range 4-18 years) performed over a 3-year period were reviewed retrospectively. Patients were separated into groups based on MRI findings: normal, ligamentous injury, osteochondral injury, or both ligamentous and osteochondral injury. Two pediatric radiologists blinded to the MRI findings reviewed the knee radiographs in consensus and categorized the findings into the same groups. Radiographic and MRI findings were compared, and the influence of radiographic findings on MRI interpretation was designated as noncontributory if radiographic findings did not aid MRI interpretation, erroneous for false-negative and false-positive radiographic findings, or helpful if radiographs aided MRI interpretation. RESULTS Radiographic findings were normal in 166 of 194 cases (86%). Among the 166, MRI findings were normal in 73 (44%) cases and abnormal in 93 (56%). Twenty-five of 28 patients (89%) with abnormal radiographic findings had abnormal MRI findings. Radiographs were deemed helpful in 14 of the 25 cases (56%) and noncontributory in 11 (44%). Overall, radiographs were helpful in 14 of 194 cases (7%), noncontributory in 84 (43%), and erroneous in 96 (50%). CONCLUSION In the interpretation of knee MRI studies requested by pediatric sports medicine and orthopedic subspecialists for knee pain, radiographs provide limited marginal value. Reliable clinical predictors are needed to identify which subset of pediatric patients with knee pain referred for MRI will benefit from the acquisition of knee radiographs.

Pre-authorization processes have no effect on patients undergoing knee MRI in a pediatric setting when evaluated by specialists

ObjectivePre-authorization processes are often used by medical insurance companies to reduce costs by managing the utilization of advanced diagnostic imaging, and their impact on patient care is unclear. The purpose of our study is to determine if a pre-authorization process increases the rate of surgically significant abnormal knee MRI and surgical referrals compared with patients referred from pediatric orthopedic specialists who do not undergo a pre-authorization process.Materials and methodsA retrospective study was performed; 124 patients were identified who were referred for knee MRI by a pediatric orthopedist. The study population included patients who underwent an insurance pre-authorization process and the control group consisted of those who did not. The results of the MRI and whether they were deemed surgically significant, in addition to surgical referral, were recorded and compared.ResultsThe study and control groups showed no statistically significant difference in outcome with regard to surgically significant findings on MRI (p = 0.92) or whether the patient required surgery (p = 0.6).ConclusionsIn this population, there is no difference in the likelihood of an abnormal knee MRI demonstrating surgically significant findings or referral to surgery in patients who did and those who did not undergo an insurance pre-authorization process when patients are referred from a pediatric orthopedic specialist. The insurance pre-authorization process does not appear to have an impact on patient diagnosis and treatment and may unnecessarily add bureaucracy and costs.

Hamate-pisiform coalition complicated by fracture in a pediatric patient

Coalition of the carpal bones is a relatively uncommon anatomic anomaly. The majority of carpal coalitions occur between the lunate and triquetrum. There are rare reports of coalition involving the hamate and pisiform. We report a case of a previously asymptomatic male who sustained minor trauma and was found to have hamate-pisiform coalition complicated by a minimally displaced pisiform fracture.

Modified Friedman technique: a new proposed method of measuring glenoid version in the setting of glenohumeral dysplasia

BackgroundGlenoid version angles are measured to objectively follow changes related to glenohumeral dysplasia in the setting of brachial plexus birth palsy. Measuring glenoid version on cross-sectional imaging was initially described by Friedman et al. in 1992. Recent literature for non-dysplastic shoulders advocates time-consuming reconstructions and reformations for an accurate assessment of glenoid version.ObjectiveTo compare Friedman’s original method for measuring glenoid version to a novel technique we developed (“modified Friedman”) with the reference standard of true axial reformations.Materials and methodsWith institutional review board approval, we retrospectively examined 30 normal and dysplastic shoulders obtained from magnetic resonance imaging examinations of 30 patients with an established diagnosis of brachial plexus birth palsy between January 2012 and September 2017. Four pediatric radiologists performed glenoid version measurements using Friedman’s method, the modified Friedman method and a previously described true axial reformation method. The modified Friedman technique better accounts for scapular positioning by selecting a reference point related to the acromion-scapular body interface. Inter-rater reliability and inter-method agreement were assessed using intraclass correlation, paired t-tests and mixed linear model analysis. Equivalence tests between methods were performed per reader.ResultsGlenoid version measurements were significantly different when comparing Friedman’s method to true axial reformations in normal (-10.8±5.7° [mean±standard deviation] vs. -8.8±5.3°; P≤0.001) and dysplastic shoulders (-34.6±17.7° vs. -28.1±17.5°; P≤0.001). Glenoid version measurements were not significantly different when comparing the modified Friedman’s method to true axial reformations in normal (-6.3±5.8° vs. -8.8±5.3°; P=0.06) and dysplastic shoulders (-29.0±18.3° vs. -28.1±17.5°; P=0.06). Friedman’s method was not equivalent to true axial reformations for measurements in dysplastic shoulders for all readers (P=0.68, 0.81, 0.86, 0.99); the modified Friedman method was equivalent to of true axial reformations for measurements in dysplastic shoulders for 3 of 4 readers (P≤0.001, P≤0.001, P≤0.001, P=0.10).ConclusionIn glenohumeral dysplasia, the modified Friedman method and post-processed true axial reformations provide statistically similar and reproducible values. We propose that our modified Friedman technique can be performed in lieu of post-processed true axial reformations to generate glenoid version measurements.