Magnetic resonance imaging of knee injuries in children

Diagnostic Performance of MRI Versus CT in the Evaluation of Intra-articular Osteochondral Fracture in Pediatric Patients With Acute Traumatic Lateral Patellar Dislocation

Background:

Evaluation of intra-articular osteochondral fractures in children with acute traumatic lateral patellar dislocation (LPD) is important for determining treatment options.

Purpose:

To (1) compare the diagnostic accuracy of computed tomography (CT) and magnetic resonance imaging (MRI) for evaluating intra-articular osteochondral fractures; (2) compare the interpretation of CT and MRI images between radiologists and pediatric orthopaedic surgeons (POS); and (3) investigate any clinical factors influencing the accuracy of CT and MRI evaluations.

Study Design:

Cohort study (diagnosis); Level of evidence, 2.

Methods:

We reviewed 35 knees in 35 patients (mean age, 12.2 ± 1.2 years; 12 boys and 23 girls) who were treated arthroscopically for acute traumatic LPD; 71% of the patients had patellar fractures, 54% had femoral fractures, and 60% had free osteochondral fracture fragments. All presurgical MRI and CT images were reviewed by POS who were blinded to both the reports of the radiologists and surgical records. We compared the accuracy of CT and MRI in diagnosing intra-articular osteochondral fractures against the arthroscopic findings and compared the interpretation of the images by the POS (MRI-O, CT-O) with those of the radiologists (MRI-R, CT-R).

Results:

There was no significant difference in diagnostic accuracy between CT and MRI for overall intra-articular osteochondral fractures by the POS or the radiologists; however, the CT-O images had a higher diagnostic specificity (84.2% vs 69.6%; P < .001) and sensitivity (88.1% vs 70.1%; P < .001) versus the MRI-R images. Regarding free fracture fragments, the CT-R images had a higher diagnostic accuracy than the MRI-R images (73.5% vs 47.1%; P = .026). When backed by clinical data, the MRI-O images had greater diagnostic accuracy (78.7% vs 60.3%; P = .001) and sensitivity (88.1% vs 30.7%; P = .021) but lower specificity compared with the MRI-R images, and the CT-O images had similar diagnostic accuracy but greater sensitivity than the CT-R images (70.1% vs 52.2%; P < .001). The diagnostic accuracy of MRI-O images was lower for children under 12 years versus children 12 years and over (67.5% vs 83.3%; P = .040).

Conclusion:

Compared with MRI, CT scans had better diagnostic performance in the evaluation of intra-articular osteochondral fractures in pediatric patients with acute traumatic LPD. Clinical data enhanced the diagnostic sensitivity of MRI and CT but decreased the specificity of MRI. MRI evaluations remain challenging for both POS and radiologists.

Sensitivity and Specificity of MRI in Diagnosing Concomitant Meniscal Injuries With Pediatric and Adolescent Acute ACL Tears

Background:

Preoperative diagnosis of concomitant meniscal tears in pediatric and adolescent patients with acute anterior cruciate ligament (ACL) deficiency is challenging.

Purpose:

To investigate the diagnostic performance of magnetic resonance imaging (MRI) in detecting meniscal injuries for pediatric and adolescent patients with acute ACL tears.

Study Design:

Cohort study (diagnosis); Level of evidence, 2.

Methods:

The authors retrospectively identified patients aged ≤18 years who underwent acute ACL reconstruction between 2006 and 2018 at 2 tertiary academic hospitals. The primary outcomes were arthroscopically confirmed medial, lateral, or any (defined as medial and/or lateral) meniscal tears. To control for chronically deficient knees, patients must have received their MRI study within 4 weeks of injury and must have undergone surgery no more than 8 weeks after their MRI study. Preoperative MRI reports were compared with the gold standard of arthroscopically confirmed tears to calculate sensitivity, specificity, positive predictive value, and negative predictive value. In a secondary analysis, patients were stratified by age into 2 groups (≤13 or ≥14 years), body mass index-for-age data from the Centers for Disease Control were used to classify patients as obese or nonobese, and differences between sensitivity and specificity proportions were analyzed using chi-square test for homogeneity.

Results:

Overall, 406 patients with a mean age of 15.4 years (range, 10-18 years) were identified. The sensitivity, specificity, positive predictive value, and negative predictive value were as follows: for lateral meniscal (LM) tears, 51.0%, 86.5%, 78.3%, and 65.0%; for medial meniscal tears, 83.2%, 80.6%, 62.3%, and 92.5%; and for any meniscal tear, 75.0%, 72.1%, 81.5%, and 63.8%, respectively. In the stratified analysis, MRI was less specific for the following diagnoses: any meniscal tear in patients aged ≤13 years (P = .048) and LM tears in obese patients (P = .020).

Conclusion:

The diagnostic ability of MRI to predict meniscal injuries present at acute ACL reconstruction was moderate. Performance was poorest at the lateral meniscus, where MRI failed to detect 97 tears that were found arthroscopically. Specificity was significantly lower in younger patients for any meniscal tear and in obese patients for LM tears.

Pediatric patellar dislocation

Acute patellar dislocation affects approximately 1:1000 healthy children 9-15 years of age, and up to 50% are at risk for recurrent dislocations. In adults the condition is associated with long-term complications, such as osteoarthritis and impairment of knee function. However, literature describing the outcome in a pediatric population is sparse. The present review article evaluates the long-term effects on knee function and cartilage quality after traumatic patellar dislocation in childhood, and also to evaluate the reliability of two clinical tests of medio-lateral knee position, in healthy children.

Imaging Evaluation of Pediatric Extremity Trauma, Part III: Lower Extremity and Soft Tissues

Lower extremity injuries are slightly less common than upper extremity injuries in children, and the structures below the knee are more often involved. Impaction injuries are often associated with twisting forces which can result in subtle buckle and hairline types of fractures, particularly in young children. Epiphyseal-metaphyseal injuries are especially common at the ankle. A variety of avulsion fractures also occur in the lower extremities, often associated with injury to nearby cartilaginous and ligamentous structures. This article reviews the important plain radiograph findings of lower extremity injuries in children as well as indications for special imaging such as ultrasound and MRI.

Occult Intra-articular Knee Injuries in Children With Hemarthrosis

BACKGROUND

Hemarthrosis after acute knee trauma is a sign of a potentially serious knee injury. Few studies have described the epidemiology and detailed injury spectrum of acute knee injuries in a general pediatric population.

PURPOSE

To document the current injury spectrum of acute knee injuries with hemarthrosis in children aged 9 to 14 years and to describe the distribution of sex, age at injury, type of activity, and activity frequency in this population.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

All patients in the Stockholm County area aged 9 to 14 years who suffered acute knee trauma with hemarthrosis were referred to Astrid Lindgren Children's Hospital, Karolinska University Hospital, from September 2011 to April 2012. The patients underwent clinical examination, radiography, and magnetic resonance imaging (MRI). The type of activity when injured, regular sports activity/frequency, and patient sex and age were registered. The diagnoses were classified into minor and serious injuries.

RESULTS

The study included 117 patients (47 girls and 70 boys; mean age, 13.2 years). Seventy percent had a serious knee injury. Lateral patellar dislocations, anterior cruciate ligament ruptures, and anterior tibial spine fractures were the most common injuries, with an incidence of 0.6, 0.2, and 0.1 per 1000 children, respectively. The sex distribution was equal up to age 13 years; twice as many boys were seen at the age of 14 years. The majority of injuries occurred during sports. Forty-six patients (39%) had radiographs without a bony injury but with a serious injury confirmed on MRI.

CONCLUSION

Seventy percent of the patients aged 9 to 14 years with traumatic knee hemarthrosis had a serious intra-articular injury that needed specific medical attention. Fifty-six percent of these patients had no visible injury on plain radiographs. Physicians who treat this group of patients should consider MRI to establish the diagnosis when there is no or minimal radiographic findings. The most common serious knee injury was a lateral patellar dislocation. This should be taken into consideration to improve prevention strategies and treatment algorithms in pediatric knee injuries.

Anterior cruciate ligament injuries: diagnosis, treatment, and prevention

The number of anterior cruciate ligament (ACL) injuries reported in athletes younger than 18 years has increased over the past 2 decades. Reasons for the increasing ACL injury rate include the growing number of children and adolescents participating in organized sports, intensive sports training at an earlier age, and greater rate of diagnosis because of increased awareness and greater use of advanced medical imaging. ACL injury rates are low in young children and increase sharply during puberty, especially for girls, who have higher rates of noncontact ACL injuries than boys do in similar sports. Intrinsic risk factors for ACL injury include higher BMI, subtalar joint overpronation, generalized ligamentous laxity, and decreased neuromuscular control of knee motion. ACL injuries often require surgery and/or many months of rehabilitation and substantial time lost from school and sports participation. Unfortunately, regardless of treatment, athletes with ACL injuries are up to 10 times more likely to develop degenerative arthritis of the knee. Safe and effective surgical techniques for children and adolescents continue to evolve. Neuromuscular training can reduce risk of ACL injury in adolescent girls. This report outlines the current state of knowledge on epidemiology, diagnosis, treatment, and prevention of ACL injuries in children and adolescents.

Magnetic resonance imaging of the immature skeleton

Magnetic resonance (MR) is unique in its ability to allow assessment of bone marrow, epiphyseal, physeal, and articular cartilage as well as tendons and ligaments. An understanding of skeletal maturation and the accompanying changes on MR is of utmost importance in pediatric radiology. In particular, it is important to recognize the normal spectrum related to ossification and marrow transformation. This review will include a brief description of main indications and common pitfalls in musculoskeletal MR in children. Also, we will focus on the MR appearance of the growing pediatric skeleton on the most commonly used sequences.

Accuracy of 3-Tesla magnetic resonance imaging for the diagnosis of intra-articular knee injuries in children and teenagers

BACKGROUND

Magnetic resonance imaging (MRI) is a commonly used tool for the diagnosis of intra-articular knee pathologies. Although many studies have reported the accuracy of MRI in the adult population, fewer studies have investigated these tests in younger patients. Furthermore, these studies have shown a higher variability in both the sensitivity and the specificity of MRI for these knee injuries in this age group. Advancements in MRI technology, such as the 3-Tesla (3T) MRI magnet, have shown promising results for musculoskeletal injury diagnosis in adults. This study aims to evaluate 3 T MRI for the diagnosis of intra-articular knee pathologies in a pediatric and adolescent patient population.

METHODS

The records of 116 patients (119 knees) under the age of 20 years who underwent 3 T MRI studies of the knee and subsequent knee arthroscopy were reviewed retrospectively. The MRI report from the musculoskeletal radiology staff, the interpretation from the staff orthopedic surgeon, and the operative note dictations were compared, with a focus on meniscus and anterior cruciate ligament (ACL) pathologies. Seventeen orthopedic staff reads were not obtainable. Arthroscopy was used as the gold standard for diagnosis.

RESULTS

The average age at MRI exam was 16.0 years and at surgery was 16.2 years. Using the musculoskeletal radiologist interpretation, the sensitivity and the specificity of 3 T MRI were 81.0% and 90.9% for medial meniscus injuries, 68.8% and 93% for lateral meniscus injuries, and 97.9% and 98.6% for ACL injuries, respectively. The orthopedic surgeon's interpretation of 3 T MRI had a sensitivity and specificity of 75.7% and 92.4% for medial meniscus injuries, 69.8% and 98.3% for lateral meniscus injuries, and 100% and 98.6% for ACL injuries, respectively. Posterior horn tears had the greatest discrepancies.

CONCLUSIONS

When performed on pediatric and adolescent patients, newer 3 T MRI studies have excellent accuracy for diagnosing ACL tears. These studies also show a higher accuracy for the diagnosis of medial meniscal tears than lateral meniscal tears.

LEVEL OF EVIDENCE

Diagnostic study--Level 2.

MRI findings in adolescent patients with acute traumatic knee hemarthrosis

BACKGROUND

Physical examination may be inconclusive in adolescents presenting with an acute traumatic knee effusion because of pain and guarding. The purpose of this study was to describe the magnetic resonance imaging (MRI) findings in adolescents with traumatic knee effusions and to compare injuries based on age, sex, and physeal maturity.

METHODS

All MRIs using a knee trauma protocol performed at our institution over a 2-year period were evaluated. One hundred thirty-one patients between the ages of 10 to 18 years of age with a clinical history of acute knee trauma and an effusion confirmed on MRI met our study inclusion criteria. They were divided into 2 age groups: 10 to 14 and 15 to 18 years old. Pathology was confirmed using clinical history, MRI, and any available surgical reports.

RESULTS

Of the 131 patients with an acute knee effusion, there were 59 patients in the younger group (10 to 14 y old) and 72 patients in the older group (15 to 18 y old). In the younger group, patellar dislocations (36%), anterior cruciate ligament (ACL) tears (22%), and isolated meniscus tears (15%) were the most common injuries. In the older group, ACL tears (40%), patellar dislocations (28%), and isolated meniscus tears (13%) were the most common injuries. ACL injuries represented 28% of injuries in males and 38% of injuries in females, whereas patellar dislocations represented 28% of injuries in males and 37% of injuries in females. There was a trend toward adolescents with active growth plates sustaining more patellar dislocations and adolescents with closed growth plates sustaining more ACL injuries. Forty-one percent of patients in this study underwent surgery.

CONCLUSIONS

Patellar dislocation is a common injury in children who present with a traumatic knee effusion, especially in young adolescents and females. Adolescents presenting with a traumatic knee effusion should undergo MRI because of the high rate of positive findings missed by physical examination and plain radiographs that may warrant surgical repair or reconstruction.

LEVEL OF EVIDENCE

Level III.

The concordance of MRI and arthroscopy in traumatic meniscal lesions in children

INTRODUCTION

Traumatic meniscal lesions in children must be diagnosed quickly and efficiently as a priority in order to conserve the meniscus and safeguard the future of the knee. They are often isolated and difficult to identify clinically. In the diagnostic work up stage, an excessive resort to diagnostic arthroscopy has given way to increasing use of MRI by radiologists without pediatric specialization. The present study examined the agreement between MRI aspect and arthroscopic exploration in traumatic meniscal lesions in children.

PATIENTS AND METHODS

Sixty-nine knees in children aged 9 to 16 years having undergone MRI followed by arthroscopy for knee trauma between 1995 and 2008 were included in a retrospective design. Discoid meniscus was excluded. Files were reviewed by a single clinician and MRI scans by a radiologist specialized in pediatric pathology. Cases of epiphyseal fusion were excluded. All files were analyzable. Agreement with arthroscopic findings as reference was assessed for presence, location and type of meniscal lesion.

RESULTS

Overall agreement with arthroscopy was respectively 78% and 82% on first and second MRI readings: 77% and 80% for the medial, and 78% and 84% for the lateral meniscus. On the first reading, there were 13 false positives for the medial and 5 for the lateral meniscus, versus 9 and 0 respectively on second reading. Overall sensitivity was 70% on first reading and 64% on second, and overall specificity 81% and 90%, respectively.

DISCUSSION

The present results, in line with the literature, may appear encouraging, but hide considerable disparity between analysis of the medial and of the lateral meniscus: MRI overestimated medial and underestimated lateral meniscus lesions.

CONCLUSION

MRI serves only as a support and does not provide sure diagnosis of meniscus lesion. Interpretation should take account of the clinical examination and the pediatric orthopedic specialist's experience.

Verification bias: an under-recognized source of error in assessing the efficacy of MRI of the meniscii

RATIONALE AND OBJECTIVES

The sensitivity and specificity of magnetic resonance imaging (MRI) for diagnosis of meniscal tears has been studied extensively, with tears usually verified by surgery. However, surgically unverified cases are often not considered in these studies, leading to verification bias, which can falsely increase the sensitivity and decrease the specificity estimates. Our study suggests that such bias may be very common in the meniscal MRI literature, and illustrates techniques to detect and correct for such bias.

MATERIALS AND METHODS

PubMed was searched for articles estimating sensitivity and specificity of MRI for meniscal tears. These were assessed for verification bias, deemed potentially present if a study included any patients whose MRI findings were not surgically verified. Retrospective global sensitivity analysis (GSA) was performed when possible.

RESULTS

Thirty-nine of the 314 studies retrieved from PubMed specifically dealt with meniscal tears. All 39 included unverified patients, and hence, potential verification bias. Only seven articles included sufficient information to perform GSA. Of these, one showed definite verification bias, two showed no bias, and four others showed bias within certain ranges of disease prevalence. Only 9 of 39 acknowledged the possibility of verification bias.

CONCLUSION

Verification bias is underrecognized and potentially common in published estimates of the sensitivity and specificity of MRI for the diagnosis of meniscal tears. When possible, it should be avoided by proper study design. If unavoidable, it should be acknowledged. Investigators should tabulate unverified as well as verified data. Finally, verification bias should be estimated; if present, corrected estimates of sensitivity and specificity should be used. Our online web-based calculator makes this process relatively easy.

[Proximal tibial fractures]

Only 1-4% of all long bone fractures in children involve the proximal tibia. To evaluate these fractures appropriately, it is mandatory to differentiate between articular fractures and metaphyseal fractures. Articular fractures of the proximal physis are rare and include Salter Harris type III and IV injuries. The reconstruction of the articular surface is the fundamental goal of therapy. Injuries of the anterior crucial ligament which typically appear as an avulsion of the tibial spine and the avulsion fracture of the tibial tubercle apophysis can involve the articular surface. Dislocated fractures should be reduced and stabilized. Extraarticular fractures include Salter Harris type I and II fractures. Other types of metaphyseal fractures are the complete fracture, the compression fracture and the bending fracture of the proximal tibia. Care should be taken while treating bending fractures, especially a valgus deformity must be excluded. Due to unequal growth stimulation during remodelling, a progressive valgus deformity frequently develops. Small deformities in the sagittal plane can be compensated by spontaneous remodelling during further growth. Dislocated fractures should be reduced and stabilized by K-wires. The retention of bending fractures by a compression plate or external fixator for medial compression might be more beneficial.

MRI of the knee: key points in the pediatric population

The knee is the joint which is most commonly imaged by MRI in children. With increasing participation in competitive sports at younger ages, knee injuries are common in children. While older adolescents have patterns of injury similar to those seen in adults, injuries seen in skeletally immature patients differ. In this essay, the MR findings of injuries of the skeletally immature knee are highlighted.

MRI of anterior cruciate ligament injuries and associated findings in the pediatric knee: changes with skeletal maturation

OBJECTIVE

The objective of our study was to evaluate the MRI characteristics of anterior cruciate ligament (ACL) injuries and associated findings relative to skeletal maturity. We also contrast the frequency of findings in this younger population to adult data.

MATERIALS AND METHODS

Eighty-two consecutive knees with an MRI report diagnosis of ACL injury (partial tear, sprain, or complete tear) or tibial spine avulsion fracture imaged over 4 years were retrospectively reviewed. Patients were grouped by degree of skeletal maturity as determined from the MR images. The examinations were reviewed for the type of ACL injury, secondary imaging findings, and associated knee injuries. Findings were correlated to skeletal maturity, and frequencies were compared with adult data.

RESULTS

ACL injuries were more common in boys in the skeletally immature group, but more common in girls in the skeletally mature group (p = 0.03). Tibial spine avulsion fractures were most common in skeletally immature patients (p < 0.01), whereas complete tears of the ACL were most common in skeletally mature patients. Associated injuries were less common in the skeletally immature group, but this trend did not reach statistical significance. Most secondary signs of ACL injuries occurred at similar rates in all groups with frequencies similar to those reported in adults.

CONCLUSION

ACL injuries in skeletally immature patients are seen more often in boys. Tibial avulsion fractures and partial tears are more common in younger, less rigid skeletons that may absorb the forces of trauma. As children mature, complete ACL tears and associated injuries occur in frequencies approaching those patterns seen in adults. Similarly, skeletally mature girls are affected more often than mature boys.

MRI findings in Dyggve-Melchior-Clausen syndrome, a rare spondyloepiphyseal dysplasia

We present the case of an 8-year-old female patient with bone dysplasia as part of Dyggve-Melchior-Clausen syndrome (DMCS). MRI was used to evaluate the case. In the spine, odontoid apophysis aplasia was found with no ossification nucleus, vertebrae with central hump, disk protrusions, hypertrophy of the posterior common vertebral ligament, and hidden spina bifida at the S4 level. Morphological anomalies were found in the hips both in the proximal femoral epiphysis, which was located excentrically and laterally to the femoral neck, and in the Y-cartilage, which was greatly enlarged. In the knees, anterior crossed ligaments were not seen, although there were some indirect signs that indicated congenital absence, including hypoplasia of the femoral trochlea and the intercondylar notch. There was bilateral medial patellar plicae and asymmetry in the height of the distal femoral and proximal tibial physes, as well as dysplasia of the facets of the patella. In comparison with radiography, MRI provides a much clearer definition of the aspects of bone dysplasia that are related to DMCS, including morphological changes in the soft tissue and cartilage of the spine, hips, and knees. MRI can enhance our understanding of the pathogenesis and evolution of deformities.

Anterior cruciate ligament injury in pediatric and adolescent soccer players: an analysis of insurance data

Injury claims from an insurance company specializing in soccer coverage were reviewed for a 5-year period. A total of 8215 injury claims (3340 females, 4875 males) were divided into three categories: (1) all injury, (2) knee injury, and (3) ACL injury. Knee injuries accounted for 22% of all injuries (30% female, 16% male). ACL injury claims represented 31% of total knee injury claims (37% female, 24% males). The youngest ACL injury was age 5. The ratio of knee injury/all injury increased with age. Compared with males, females demonstrated a higher ratio of knee injury/all injury and a higher ratio of ACL injury/all injury. This study demonstrates that ACL injury occurs in skeletally immature soccer players and that females appear to have an increased risk of ACL injury and knee injury compared with males, even in the skeletally immature. Future research related to ACL injury in females will need to consider skeletally immature patients.

Meniscal disorders: normal, discoid, and cysts

Meniscal injuries in children and adolescents are being seen with increased frequency. Meniscal tears are typically traumatic injuries in adolescents. Because of increased healing potential and the younger age of these patients, attempts at meniscal preservation should be emphasized for outer and middle third tears. Discoid meniscus typically presents as a snapping knee in younger children or as a meniscal tear in older children. Again, meniscal preservation by saucerization is emphasized. Careful attention should be given to the need for additional meniscal repair. Popliteal cysts typically present as a painless mass. Because they are usually not associated with an internal pathology and often resolve spontaneously, the preferred treatment is observation.

Magnetic resonance imaging of the pediatric knee

Magnetic resonance imaging (MRI) is an excellent modality for imaging the pediatric knee because of its superb soft-tissue contrast, multiplanar capability, and lack of ionizing radiation. The knee is the most common joint imaged by MRI in the pediatric population. The majority of studies are performed on older children or adolescents with pain and/or known trauma. There are variations of injury and patterns of injury that are unique to children. The knee of a child also may be studied by MRI for other indications, including tumor, inflammatory disease, and developmental abnormalities. It is important to have a systematic approach to analysis of the knee MR images. Analysis should include individual attention to bones, articular cartilage, muscles and tendons, soft tissues, neurovascular bundle, joint space, fluid collections, ligaments, and menisci.

MR imaging of children's knees

The spectrum of paediatric knee disorders ranges from developmental and growth disorders, traumatic derangement, inflammation, infection, and diffuse marrow disorder to neoplasm. We present in this pictorial review the MR imaging findings used to characterize these various diseases affecting the knee region of children and adolescents.

Diagnostic performance of clinical examination and selective magnetic resonance imaging in the evaluation of intraarticular knee disorders in children and adolescents

To determine the diagnostic performances of clinical examination and selective magnetic resonance imaging in the evaluation of intraarticular knee disorders in children and adolescents we compared them with arthroscopic findings in a consecutive series of pediatric patients (< or = 16 years old). Stratification effects by patient age and magnetic resonance imaging center were examined. There were 139 lesions diagnosed clinically, 128 diagnosed by magnetic resonance imaging, and 135 diagnosed arthroscopically. There was no significant difference between clinical examination and magnetic resonance imaging with respect to agreement with arthroscopic findings (clinical examination, 70.3%; magnetic resonance imaging, 73.7%), overall sensitivity (clinical examination, 71.2%; magnetic resonance imaging, 72.0%), and overall specificity (clinical examination, 91.5%; magnetic resonance imaging, 93.5%). Stratified analysis by diagnosis revealed significant differences only for sensitivity of lateral discoid meniscus (clinical examination, 88.9%; magnetic resonance imaging, 38.9%) and specificity of medial meniscal tears (clinical examination, 80.7%; magnetic resonance imaging, 92.0%). For magnetic resonance imaging, children younger than 12 years old had significantly lower overall sensitivity (61.7% versus 78.2%) and lower specificity (90.2% versus 95.5%) compared with children 12 to 16 years old. There was no significant effect of magnetic resonance imaging center. In conclusion, selective magnetic resonance imaging does not provide enhanced diagnostic utility over clinical examination, particularly in children, and should be used judiciously in cases where the clinical diagnosis is uncertain and magnetic resonance imaging input will alter the treatment plan.

Anterior cruciate ligament tears: MR imaging-based diagnosis in a pediatric population

PURPOSE

To evaluate the diagnostic accuracy of primary and secondary magnetic resonance (MR) imaging findings of anterior cruciate ligament (ACL) tears in young patients with immature skeletal systems.

MATERIALS AND METHODS

MR images obtained in 43 patients aged 5-16 years who underwent arthroscopy were retrospectively reviewed. Two reviewers evaluated primary findings (abnormal signal intensity, abnormal course as defined by Blumensaat angle, and discontinuity), secondary findings (bone bruise in lateral compartment, anterior tibial displacement, uncovering of posterior horn of lateral meniscus, posterior cruciate ligament line, and posterior cruciate angle), and meniscal and other ligamentous injuries.

RESULTS

There were 19 ACL tears and 24 intact ACLs. Overall sensitivity and specificity of MR imaging in detecting ACL tears were 95% and 88%, respectively. Sensitivities of the primary findings were 94% for abnormal Blumensaat angle; 79%, abnormal signal intensity; and 21% discontinuity. The specificity of all primary findings was 88% or greater. The sensitivity and specificity of the secondary findings, respectively, were 68% and 88% for bone bruise; 63% and 92%, anterior tibial displacement; 42% and 96%, uncovered posterior horn of lateral meniscus; 68% and 92%, positive posterior cruciate line; and 74% and 71%, abnormal posterior cruciate angle. Fifteen (79%) patients had meniscal tears, and five (26%) had collateral ligament injuries.

CONCLUSION

Primary and secondary findings of ACL tears in young patients have high specificity and are useful for diagnosis.

Correlation of MRI and arthroscopic diagnosis of knee pathology in children and adolescents

The accuracy of magnetic resonance imaging (MRI) in diagnosing knee pathology in the pediatric and adolescent population is not well established. The purpose of this study was to correlate the findings of MRI and knee arthroscopy in children and adolescents. One hundred and eight consecutive knee arthroscopies performed in patients ages 4-17 years between 1992 and 1996 were retrospectively reviewed. Fifty-three of these patients underwent preoperative MRI. Age-related comparisons were then made between MRIs and observed intraoperative meniscal and anterior cruciate ligament pathology. The pediatric group (ages 4-14 years) was demonstrated to have an appreciable decrease in sensitivity, specificity, positive predictive value, and accuracy for essentially all categories of pathologic changes. Conversely, negative predictive values for the pediatric group exceeded those of the adolescent group (ages 15-17 years) in each category. The ability of MRI to predict intraarticular knee pathology among adolescents is comparable to that in adults, whereas it is much less accurate in the pediatric population.

Children's sports injuries

Sports injuries in children are common. They range from very serious and even, occasionally, fatal accidents, to trivial sprains and bruises. Sports medicine is a burgeoning field. Parallel with this there has been an increased understanding of the radiology of these lesions. Lesions in the immature skeleton differ greatly to those in the mature skeleton. This review describes the most frequent sports injuries in children.