Andrew M. Zbojniewicz

Juvenile Osteochondritis Dissecans: Is It a Growth Disturbance of the Secondary Physis of the Epiphysis?

OBJECTIVE The primary physis is responsible for longitudinal bone growth. Similarly, epiphysial growth relies on endochondral ossification from the circumferential secondary physeal [corrected]. injury can result in disruption of normal ossification. The cause of juvenile osteochondritis dissecans (OCD) remains elusive. We hypothesized that juvenile OCD results from an insult affecting endochondral ossification from the secondary physis. The purpose of our study was to evaluate the MRI appearance of the distal femoral epiphysis-particularly the secondary physis-of children with juvenile OCD and to compare these findings with the MRI findings of unaffected children. MATERIALS AND METHODS Knee MRI examinations of 30 children (age range, 8 years 8 months to 13 years 4 months) with OCD and 30 matched control patients were evaluated for skeletal maturity; location of the OCD lesion, if present; secondary physeal [corrected] continuity; overlying chondroepiphysial integrity, contour, and width; signal intensity of subchondral bone; and secondary physeal [corrected] conspicuity. Variables were compared using chi-square tests. RESULTS All children were skeletally immature. Condylar lesions were medial in 24 knees and lateral in six knees. All were in the middle one third, posterior one third, or middle and posterior thirds in the sagittal plane. The majority of lesions spanned the intercondylar and middle one third of the femoral condyle in the coronal plane (73%). There was a significant difference between secondary physeal [corrected] disruption in juvenile OCD condyles compared with unaffected condyles (p < 0.001) and control condyles (p < 0.001). Compared with unaffected and control condyles, the OCD group showed chondroepiphysial widening (p < 0.001) and subchondral bone edema (p < 0.001) on MRI. Neither chondroepiphysial integrity nor chondroepiphysial contour was significantly different between groups (p = 0.21, p = 0.31, respectively). CONCLUSION MRI of children with OCD consistently showed secondary physis disruption, overlying chondroepiphysial widening, and subchondral bone edema. We suggest that disruption of normal endochondral ossification may be associated with juvenile OCD.

MR findings of synovial disease in children and young adults: Part 2

Synovium is the thin membranous lining of a joint. It produces synovial fluid, which lubricates and nourishes the cartilage and bone in the joint capsule. Synovial diseases in children can be classified as normal structures as potential sources of pathology (synovial folds: plicae, infrapatellar fat pad clefts), noninfectious synovial proliferation (juvenile idiopathic arthritis, hemophilic arthropathy, lipoma arborescens, synovial osteochondromatosis, pigmented villonodular synovitis, reactive synovitis), infectious synovial proliferation (pyogenic arthritis, tuberculous arthritis), deposition disease (gouty arthropathy), vascular malformation, malignancy (metastasis) and intra-/periarticular cysts and cyst-like structures. Other intra-articular neoplasms, such as intra-articular synovial sarcoma, can mimic synovial disease in children.

The reliability to determine "healing" in osteochondritis dissecans from radiographic assessment.

Background: Current literature supporting treatment strategies for osteochondritis dissecans (OCD) has limited prognostic utility. Presently, there is no gold standard for an OCD “healing” outcome. Accurate and reliable determination of the OCD healed status on the basis of radiographs would be valuable to provide a guide for evidence-based treatment of OCD. The purpose of this study was to determine interrater and intrarater reliability of radiographic assessment of OCD lesion healing in the knee. Methods: A hospital database identified 39 consecutive patients with OCD in 42 knees, who were treated conservatively for at least 6 months. Patients were an average age of 11.9 years (±2.4 y). A total of 102 presentation slides were prepared, each containing 2 similar radiographic views from the same patient taken 6 months (±1 mo) apart. These slides were then categorized by 4 reviewers (1 orthopaedic surgeon, 1 orthopaedic fellow, and 2 musculoskeletal radiologists) blinded to patient data, as healed, not healed, or unable to evaluate the OCD lesion. Reviewers repeated their assessment at a minimum of 3 weeks after their first read. Intrarater and interrater reliability were measured with the Cohen &kgr; coefficient and Randolph’s free-marginal multirater &kgr;, respectively, and with the percent agreement. Results: OCD lesion categorization demonstrated insufficient interrater reliability with a &kgr; of 0.44 and 63% agreement. The notch view had the highest interrater reliability with a &kgr; of 0.63% and 76% agreement, and the lateral view had the lowest interrater reliability with a &kgr; of 0.29% and 53% agreement. The OCD lesion categorization demonstrated substantial intrarater reliability with a &kgr; of 0.68% and 81% agreement. Conclusions: Reviewers did not consistently agree on the “healing” status of the OCD lesions on the basis of radiographic assessments. Standard criteria to assess healing are needed to consistently evaluate OCD knee lesions in children. Level of Evidence: Not applicable.

Imaging of osteochondritis dissecans.

Osteochondritis dissecans (OCD) can affect both adults and children, however the imaging characteristics and significance of imaging findings can differ in the juvenile subset with open physes. Radiography and magnetic resonance imaging (MRI) are the primary modalities used to aid in diagnosis, to define a treatment plan, to monitor progress, to assess surgical intervention, and to identify postoperative complications. Newer imaging techniques under continuous development may improve the accuracy of MRI for diagnosis and staging of OCD, and eventually may help to predict the durability of tissue-engineered constructs and cartilage repair.

Pediatric Triplane Ankle Fractures: Impact of Radiographs and Computed Tomography on Fracture Classification and Treatment Planning

BACKGROUND The purpose of this study was to compare the reliability of triplane fracture classification, displacement measurement, and treatment planning with the use of radiographs with and without computed tomography. METHODS One pediatric radiologist, one musculoskeletal radiologist, and three fellowship-trained pediatric orthopaedic surgeons rated a spectrum of twenty-five triplane fractures with use of radiographs alone and then with computed tomography scans on two separate occasions (two to four weeks apart). Raters classified the fracture pattern with use of the Rapariz classification system, measured the maximum intra-articular displacement, and drew the fracture on four outlines of the distal part of the tibia: one lateral view, one anteroposterior view, one axial view above the tibial physis, and one axial view below the physis. Reliability was assessed with kappa values and intraclass correlation coefficients. RESULTS The Rapariz triplane fracture classification had poor inter-rater reliability (a kappa of 0.17) and intra-rater reliability (a kappa of 0.31) with radiographs alone but moderate inter-rater reliability (a kappa of 0.41) and intra-rater reliability (a kappa of 0.54) with the addition of computed tomography. After reviewing computed tomography, raters changed the fracture pattern in 46% of ratings, the displacement from ≤2 mm to >2 mm in 39% of ratings, the treatment from nonoperative to operative in 27% of ratings, and either the orientation or number of screws in 41% of ratings. CONCLUSIONS Computed tomography had a definite impact on the fracture classification, displacement, and treatment plan, supporting its use as an adjunct to radiographs for the treatment of pediatric triplane fractures.

MRI of displaced meniscal fragments

A torn meniscus frequently requires surgical fixation or debridement as definitive treatment. Meniscal tears with associated fragment displacement, such as bucket handle and flap tears, can be difficult to recognize and accurately describe on MRI, and displaced fragments can be challenging to identify at surgery. A displaced meniscal fragment can be obscured by synovium or be in a location not usually evaluated at arthroscopy. We present a pictorial essay of meniscal tears with displaced fragments in patients referred to a pediatric hospital in order to increase recognition and accurate interpretation by the radiologist, who in turn can help assist the surgeon in planning appropriate therapy.

Juvenile Osteochondritis Dissecans: Correlation Between Histopathology and MRI

OBJECTIVE The objective of our study was to correlate specimens of juvenile osteochondritis dissecans (OCD) lesions of the knee to MRI examinations to elucidate the histopathologic basis of characteristic imaging features. MATERIALS AND METHODS Five children (three boys and two girls; age range, 12-13 years old) who underwent transarticular biopsy of juvenile OCD lesions of the knee were retrospectively included in this study. Two radiologists reviewed the MRI examinations and a pathologist reviewed the histopathologic specimens and recorded characteristic features. Digital specimen photographs were calibrated to the size of the respective MR image with the use of a reference scale. Photographs were rendered semitransparent and over-laid onto the MR image with the location chosen on the basis of the site of the prior biopsy. RESULTS A total of seven biopsy specimens were included. On MRI, all lesions showed cystlike foci in the subchondral bone, bone marrow edema pattern on proton density-or T2-weighted images, and relatively thick unossified epiphyseal cartilage. In four patients, a laminar signal intensity pattern was seen, and two patients had multiple breaks in the subchondral bone plate. Fibrovascular tissue was found at histopathology in all patients. Cleft spaces near the cartilage-bone interface and were seen in all patients while chondrocyte cloning was present in most cases. Focal bone necrosis and inflammation were infrequent MRI findings. Precise correlation of the MRI appearance to the histopathologic overlays consistently was found. CONCLUSION A direct correlation exists between the histopathologic findings and the MRI features in patients with juvenile OCD. Additional studies are needed to correlate these MRI features with juvenile OCD healing success rates.

Feasibility of ultrashort TE (UTE) imaging of children at 1.5 T.

Ultrashort TE (UTE) is a relatively new MRI technique that allows for the visualization of tissue structures with short T2 components that show little or no signal on all conventional MR imaging sequences. This technique, to the best of our knowledge, has been described only in adults and uses a half excitation pulse and radial k-space data acquisition to produce echo times of less than 100 microseconds with no need for additional hardware modifications. We describe the feasibility of using a 2-D UTE sequence in vivo on a routine 1.5 T clinical MR scanner to depict various musculoskeletal structures in children.

Imaging assessment of patellar instability and its treatment in children and adolescents

Transient patellar dislocation is a common entity in children and adolescents, characterized by lateral dislocation of the patella, usually with spontaneous reduction. Many predisposing conditions have been described, including trochlear dysplasia, excessive lateral patellar tilt, patella alta and lateralization of the tibial tuberosity. Associated injuries are bone bruises of the patella and lateral femoral condyle, tears of the medial retinaculum that include the medial patellofemoral ligament (MPFL), tears of the vastus medialis obliquus muscle, injuries of articular cartilage, and intra-articular bodies. Children who are refractory to conservative management, have a large cartilage defect, or are at substantial risk for recurrent dislocations are candidates for surgical procedures to prevent future dislocations. Procedures can include MPFL repair or reconstruction, tibial tubercle repositioning and lateral retinacular release. The purpose of this review is to illustrate the imaging findings of transient patellar dislocation in the acute setting, the normal imaging appearance after surgical intervention, and post-surgical complications.

Intracapsular Origin of the Long Head of the Biceps Tendon With Glenoid Avulsion of the Glenohumeral Ligaments

An 18-year-old woman presented with a history of recurrent glenohumeral dislocations involving her right dominant shoulder. Physical examination suggested physiologic hyperlaxity and anterior instability. Magnetic resonance arthrography demonstrated an anomalous intracapsular origin of the long head of the biceps tendon (LHBT), with normal-appearing LHBT in the intertubercular groove. Diagnostic arthroscopy confirmed the absence of the LHBT attachment on the superior labrum. Instead, the LHBT originated from the capsule of the shoulder joint. Diagnostic arthroscopy also revealed glenoid avulsion of the glenohumeral ligaments (GAGL) lesion as a tear in the anterior-inferior capsule near its insertion on the glenoid and labrum. An arthroscopic anterior capsulolabral repair was performed with rotator interval closure by imbrication of superior and middle glenohumeral ligaments. A retrospective review of the magnetic resonance arthrogram identified irregularity and interposition of contrast between the capsule and the anterior-inferior labrum that was reproduced in the abduction-external rotation view corresponding with the GAGL lesion seen at arthroscopy. At 12 months postoperatively, the patient demonstrated full range of motion and no signs of instability. This case report helps to raise awareness about 2 rare shoulder lesions: the anomalous origin of LHBT and the GAGL lesion. Diagnosing such lesions on preoperative magnetic resonance imaging may aid in operative planning and avoid unexpected intraoperative findings.