MRI evaluation of the knee in children with infantile Blount disease: tibial and extra-tibial findings

Background

Infantile Blount disease is a developmental condition characterized by disorganized endochondral ossification in the medial aspect of the proximal tibial physis.

Objective

To describe the MR imaging abnormalities in the proximal tibia, distal femur, menisci and ligaments of children with infantile Blount disease.

Materials and methods

We retrospectively evaluated 11 children (18 total knee MR examinations) with infantile Blount disease and compared them with an age-matched control group with normal MR examinations. Morphological and morphometric measurements were performed.

Results

The medial menisci were enlarged with increased T2 signal intensity in all MR examinations. The medial femoral epiphyseal cartilage showed abnormal foci of increased signal intensity in nine (50%). The mid-coronal thickness of the medial tibial epiphyseal cartilage was decreased with concomitant increase in the mid-coronal joint space distance. Angular measurements of the proximal tibia demonstrated posteromedial down-sloping configuration.

Conclusions

Most severe abnormalities of infantile Blount disease occur in the medial compartment of the knee, especially at the medial tibial physis and epiphysis. However, other important structures of the knee and the lateral compartment are often affected. MR imaging helps to delineate the extent of multiple tibial and extra-tibial abnormalities, including meniscal abnormalities, perichondrial membrane changes and premature physeal closure.     

Bilateral agenesis of the anterior cruciate ligament: MRI evaluation

Bilateral agenesis of the anterior cruciate ligament (ACL) is extremely rare. We describe a 13-year-old girl who presented with bilateral knee pain without history of trauma; she has two family members with knee instability. Magnetic resonance imaging showed bilateral absence of the ACL, and medial posterior horn meniscal tears. Bilateral arthroscopic partial meniscectomy and anterior cruciate ligament reconstruction was performed.     

Meniscal pathology in children: differences and similarities with the adult meniscus

The normal meniscus undergoes typical developmental changes during childhood, reaching a mature adult appearance by approximately 10 years of age. In addition to recognizing normal meniscal appearances in children, identifying abnormalities — such as tears and the different types of discoid meniscus and meniscal cysts, as well as the surgical implications of these abnormalities — is vital in pediatric imaging. The reported incidence of meniscal tears in adolescents and young adults has increased because of increased sports participation and more widespread use of MRI. This review discusses the normal appearance of the pediatric meniscus, meniscal abnormalities, associated injuries, and prognostic indicators for repair.     

MRI demonstration of occult purely chondral fractures of the tibia: a potential mimic of meniscal tears

We report the case of a 12-year-old boy with bilateral, purely chondral fractures of the tibia. The patient had Crohn's disease treated with systemic corticosteroids. MR images of the knee were initially interpreted to show a bucket-handle tear of the lateral meniscus. However, arthroscopic evaluation revealed purely chondral fractures of the tibial plateau without meniscal damage. Re-evaluation of the MR study identified the chondral fracture of the lateral tibial articular cartilage detected arthroscopically. This purely chondral fracture of the tibial plateau represented a rare finding in the symptomatic knee that mimicked a meniscal tear by history, physical exam, and MR imaging. Received: 10 December 1996 Accepted: 24 March 1997     

Arthroscopy of the knee in children and adolescents.

Arthroscopy of the knee was performed in 104 patients under 18 years of age, 41 in children (aged 8 to 15) and 63 in adolescents (aged 16 to 18). Most frequently lesions of the patella were found (in 45% of all diagnoses in children and 29% in adolescents), in most cases because of acute or recurrent dislocation of the patella. The incidence of meniscal lesions increased with age. The most frequent therapeutic procedure performed in children was a lateral release (34%), in adolescents a partial meniscal resection (31%). In children 43% of arthroscopies were diagnostic, in adolescents 21%. Preoperative diagnosis was shown to be incorrect or incomplete arthroscopy in 41% of children and 24% of adolescents taking arthroscopic findings as a golden standard. Preoperative diagnosis had highest accuracy for dislocation of the patella, 90% of dislocations were diagnosed correctly before arthroscopy. The lowest accuracy of clinical diagnosis was found for meniscal lesions; only 36% of meniscal tears were suspected preoperatively. In 35 of 38 patients with hemarthrosis a relevant knee lesion was found, in 23 of these patients arthroscopic therapy was performed. This justifies our concept for arthroscopy of every knee hemarthrosis. Besides superficial chondral lesions in 8 patients there were no complications associated with the procedure. It is concluded that arthroscopy of the knee in children and adolescents is a safe procedure with high diagnostic and therapeutic value.     

Development of the meniscus of the knee joint in human fetuses

Discoid meniscus of the knee joint occurs at a higher incidence in the lateral than in the medial menisci. Although its developmental origin has been suggested, it remains unclear. To verify the developmental etiology, we examined the meniscus of the knee joint in 41 human fetuses (from 14 to 30 weeks of gestation) and 14 adults (from 56 to 91 years of age) comparatively. The articular surfaces of the tibia and meniscus of the left knees in 40 fetuses and 14 adults were photographed and each area was measured by Scion Image (Scion; http://www.scioncorp.com ). Morphometric analyses revealed that the proportion of the area of meniscus to that of the plateau was continuously higher in the lateral side than in the medial side. The right knee joints of seven fetuses were histologically observed, and the layered structure of fibers developed earlier in the lateral meniscus than in the medial in fetuses. The observed differential development of lateral and medial sides of the meniscus may be involved in the etiology of discoid meniscus.     

Blount's disease: Magnetic resonance imaging

To evaluate the information obtained by magnetic resonance (MR) imaging, the radiographic and MR investigations of nine patients treated for idiopathic tibia vara were reviewed in retrospect. There were six unilateral and three bilateral cases (12 tibiae). Initial radiographs of each patient were assigned a stage according to Catonné's classification. MR imaging was performed with a 0.5- or 1.5-T apparatus. Bony epiphyses were poorly developed in all cases. The cartilaginous component of the epiphyses compensated partially (6/12 cases) or completely (6/12 cases) for the collapse of the physes. In two cases an abnormal area was found between the medial meniscus and the cartilaginous portion of the epiphysis. An abnormally large medial meniscus was noted in four cases; an abnormal signal in the medial meniscus was seen in two cases. MR imaging has several advantages over plain film: it uses no ionizing radiation, it shows the shape of the ossified and cartilaginous epiphysis, and it demonstrates meniscal and physeal abnormalities. MR imaging may influence the choice of treatment.     

What is the best treatment for a child with an acute tear of the anterior cruciate ligament?

With the heightened popularity of childhood sporting activity, the number of paediatric anterior cruciate ligament (ACL) ruptures has increased. Management of these injuries presents a particular challenge due to the open femoral and tibial growth plates. Physeal damage has the potential to cause angular deformity or length discrepancy. This review was conducted to determine the best way to treat this injury. A primary search of Ovid MEDLINE (1 October 2017) used the terms: (ACL or anterior cruciate ligament) and (young or child or children or pediatric or immature or pre‐pubescent). Titles/Abstracts of 369 articles were screened for relevance. A total of 217 were excluded, leaving 152 articles for full‐paper retrieval. Of these, 9 articles remained with one further article identified during cross‐referencing; 10 papers (1 level 2 and 9 level 3) were included for analysis. Comparative studies investigating surgical (140 knees) versus conservative (110 knees) treatment provide evidence in favour of the former, in reducing instability and meniscal tears and improving return to previous activity. Of the papers analysed (163 reconstructions), there was only one case of growth arrest (0.6%) and no cases of length discrepancy. In those studies investigating early (218 patients) versus delayed (140 patients) reconstruction, medial meniscal tears and chondral injuries occurred more frequently in the delayed group. To conclude, for children, there is level 2/3 evidence that early operative ACL reconstruction offers the best chance of a return to pre‐injury sporting activity and minimises the risks of further structural damage. Iatrogenic growth disturbance remains a rare but worrying complication.     

Discoid lateral meniscus in children

The discoid meniscus is the most common abnormal meniscal variant in children. It is most likely a congenital deviation and usually occurs laterally. The discoid shape results in greater coverage of the tibia and usually is associated with increased thickness of the meniscus that may lead to abnormal shearing forces across the knee joint. The Watanabe classification divides this anomaly into three distinct types: complete, incomplete, and Wrisberg ligament. The complete and incomplete types are often asymptomatic; unless symptomatic, they generally should be left alone. Tears should be treated with resection back to a stable rim. The Wrisberg ligament type is a hypermobile meniscus secondary to a lack of posterior tibial attachment. This type may or may not be associated with an abnormal shape and may appear in childhood as a classic snapping knee syndrome. These children complain of intermittent popping and snapping within the knee that clinically manifests as a dramatic audible and visible adjustment of the knee with each flexion and extension. Treatment of a symptomatic Wrisberg ligament type requires surgical repair of the posterior disruption. Saucerization of the remaining meniscus may be required to protect the repair from abnormal shear forces.     

Diagnostic performance of magnetic resonance arthrography of the shoulder in children

Background

No reported data demonstrate the usefulness of magnetic resonance arthrography of the shoulder in children.

Objective

To evaluate the sensitivity, specificity and accuracy of MR arthrography in the assessment of superior labral anteroposterior (SLAP) tears of the shoulder, Bankart-type injuries and Hill-Sachs lesions in children as compared to arthroscopy.

Materials and methods

We retrospectively interpreted 66 MR arthrograms of the shoulder and compared them with surgical findings. Assessment included evaluation of the osseous structures, labral-ligamentous complex and determination of skeletal maturity. We calculated sensitivity, specificity and accuracy and compared sensitivity and specificity between skeletally mature and immature children.

Results

MR arthrography demonstrated a sensitivity, specificity and accuracy of 88%, 98% and 94%, respectively, for depiction of SLAP tears; 94%, 92% and 94% for detection of Bankart-type injuries; and 100%, 94% and 97% for diagnosing Hill-Sachs lesions. There was no statistical difference between the skeletally immature and skeletally mature groups.

Conclusion

There is no significant difference in the diagnostic accuracy of MR arthrography in skeletally immature versus skeletally mature children. MR shoulder arthrography is an effective method for the detection of labral and bone pathology.     

MRI of traumatic patellar dislocation in children

Background Traumatic patellar dislocations (TPD) are common injuries in children, and MRI is useful in evaluation of pediatric musculoskeletal injuries. However, no pediatric studies on the MR features of TPD have been reported. Objective To review the injuries after TPD in children. Materials and methods Patients with clinical or radiological recognition of TPD and those with suggestive MR findings were selected. Bone, cartilage and soft-tissue injuries and patellofemoral relationships were assessed. Results A total of 26 patients (age range 10–18 years) were identified. The following injuries were seen: bone bruising of the inferomedial patella (81% of patients) and the lateral femoral condyle (81% of patients), cartilage injuries of the inferomedial patella (38% of patients) and the lateral femoral condyle (38% of patients), osteochondral fragments (42% of patients) and injuries of the medial patellar restraints (81% of patients). Conclusion Pediatric manifestations of TPD seen on MRI are similar to those in adults. TPD is often occult in children. Early recognition of bone bruising of the patella and lateral femoral condyle, associated osteochondral injuries, and medial patellar stabilizer injury is important for timely diagnosis.     

MR imaging assessment of the lateral head of the gastrocnemius muscle: prevalence of segmental anomalous origins in children and young adults

BACKGROUND: Variations in the lower extremity musculature have been identified, including an anomalous origin of the medial head of the gastrocnemius muscle. Anomalies of the lateral head of the gastrocnemius muscle (LGN) have been less frequently described, especially in children. OBJECTIVE: To describe the MR imaging appearance, frequency and clinical symptoms associated with anatomic variations of the LGN in children and young adults. MATERIALS AND METHODS: A retrospective review of 465 knee MR imaging examinations was performed. The site of origin of the LGN was identified as either normal, lateral segmental anomalous origin (LSAO), or medial accessory anomalous origin (MAAO). The clinical indication for imaging was recorded. RESULTS: An anatomic variation of the LGN was identified in 16 patients (3.4%). Nine patients had LSAO, and five of these had symptoms referable to or abnormalities of the patella. Seven patients had MAAO, and three of these had chronic nontraumatic knee pain. CONCLUSION: Anatomic variations of the LGN are not rare in young patients, occurring with a frequency of 3.4% in our series. It is unknown whether these anomalies play a role in the etiology of patellofemoral pain or unexplained joint pain in children.     

MR findings of bowlegs in toddlers

Background. Toddlers with severe physiologic tibial bowing are considered to be at risk for the development of Blount's disease. Objective. To correlate MR findings of the knee with the clinical outcome in toddlers with severe physiological tibial bowing. Materials and methods. MR findings were evaluated in 22 affected legs of 14 children with severe tibial bowing (mean age 1.9 years). In 18 affected legs, MR findings were compared with the transition of the tibial metaphyseal-diaphyseal angle (MDA) and tibiofemoral angle (TFA) measured serially between 2 and 3 years of age. Results. MR findings of severe tibial bowing comprised undulation of the posteromedial physis of the tibia (3/22), signal alterations in the medial tibial metaphysis (10/22), T2 prolongation in the posteromedial tibial epiphyseal cartilage (14/22) and signal changes in the medial menisci (18/22). The decrease in the TFA was different in the legs with and without increased signal in the epiphyseal cartilage, and the decrease in the MDA was different in the legs with and without physeal undulation. Conclusion. MR imaging findings can predict the retarded resolution of tibial bowing, which may be a risk factor for the development of Blount's disease. Received: 16 December 1998 Accepted: 20 May 1999     

MR of physeal fractures of the adolescent knee

The aim of this study was to assess physeal fractures of the pediatric knee identified by MR imaging and to describe the MR findings of such fractures. The authors reviewed 315 consecutive pediatric knee MR examinations done to assess for traumatic injury. The MR images were reviewed for evidence of physeal fracture. Fractures were classified by the Salter-Harris system, and associated findings and injuries were noted. Plain radiographs and medical records were reviewed. Seven distal femoral physeal fractures (Salter II, n = 6; Salter III, n = 1) and two proximal tibia physeal fractures (Salter III, n = 1; complex Salter IV, n = 1) were identified. Magnetic resonance demonstrated widening of a portion of the physis with visualization of a metaphyseal/epiphyseal fracture line. Periosteal elevation was observed in six cases. Four patients had associated ligamentous or meniscal injuries. Plain radiographs were available for review in eight patients. Bone abnormalities suggesting fracture were evident in six of eight patients; however, the fracture was fully delineated in only one patient. The diagnosis or confirmation of fracture by MR changed clinical management in seven of eight patients in whom follow-up was available. Physeal fractures of the pediatric knee are occasionally diagnosed by MR. Magnetic resonance provides improved delineation of non-displaced physeal fractures of the knee, while simultaneously allowing for evaluation of soft tissue structures. Received: 25 October 1999/Accepted: 6 June 2000     

Optimizing bone surveys performed for suspected non-accidental trauma with attention to maximizing diagnostic yield while minimizing radiation exposure: utility of pelvic and lateral radiographs

Background

Skeletal surveys for non-accidental trauma (NAT) include lateral spinal and pelvic views, which have a significant radiation dose.

Objective

To determine whether pelvic and lateral spinal radiographs should routinely be performed during initial bone surveys for suspected NAT.

Materials and methods

The radiology database was queried for the period May 2005 to May 2011 using CPT codes for skeletal surveys for suspected NAT. Studies performed for skeletal dysplasia and follow-up surveys were excluded. Initial skeletal surveys were reviewed to identify fractures present, including those identified only on lateral spinal and/or pelvic radiographs. Clinical information and MR imaging was reviewed for the single patient with vertebral compression deformities.

Results

Of the 530 children, 223 (42.1%) had rib and extremity fractures suspicious for NAT. No fractures were identified solely on pelvic radiographs. Only one child (<0.2%) had vertebral compression deformities identified on a lateral spinal radiograph. This infant had rib and extremity fractures and was clinically paraplegic. MR imaging confirmed the vertebral body fractures.

Conclusion

Since no fractures were identified solely on pelvic radiographs and on lateral spinal radiographs in children without evidence of NAT, nor in nearly all with evidence of NAT, inclusion of these views in the initial evaluation of children for suspected NAT may not be warranted.     

Popliteal cysts in children: prevalence, appearance and associated findings at MR imaging

Objective. The purpose of this study was to determine the prevalence of Baker's cysts on MR images in a paediatric orthopaedic population, to investigate the association of Baker's cyst with joint fluid and joint disorders in children, and to compare the MR appearance of Baker's cysts in children with that previously reported in adults. Materials and methods. Reports from 393 MR studies of the knee performed in children aged from 1 to 17 years were retrospectively reviewed for the presence of a Baker's cyst, joint effusion, meniscal tear, anterior cruciate ligament tear, or any other joint disorder. Results. A Baker's cyst was identified in 6.3 % (25/393) of patients. The MR images and clinical charts of patients with a Baker's cyst were reviewed. None of the 25 patients with a Baker's cyst had an associated anterior cruciate ligament tear or meniscal tear. Two patients had osteochondritis dissecans and two others had synovial disease (infection and juvenile rheumatoid arthritis). Joint fluid was demonstrated in 16 % (4/25) of patients with a Baker's cyst. There was no statistically significant association between presence of a Baker's cyst and presence of joint fluid. Conclusions. Baker's cyst is less prevalent in a paediatric orthopaedic population than in an adult population. In children, it seems that Baker's cyst is seldom associated with joint fluid, meniscal tear, or anterior cruciate ligament tear. On MR images, a communication between the Baker's cyst and the joint was not demonstrated in any of the patients. In addition, the presence of debris and cyst leakage was not observed. Received: 20 August 1998 Accepted: 15 February 1999     

MR imaging in congenital lower limb deformities

Treatment for children with congenital deformities of the lower extremities may vary, depending on the state of the unossified skeletal structures and surrounding soft tissues. The purpose of our study was to demonstrate the spectrum of the osteochondral and extrasosseous abnormalities as depicted with MR imaging. We retrospectively reviewed MR examinations of 13 limbs of ten children (aged 1 month-9 years, mean 2.1 years) with longitudinal and transverse deformities of the lower extremities. The lesions imaged were fibular hemimelia (n = 5), tibial hemimelia (n = 5), and congenital constriction bands (n = 3). Each examination was assessed for abnormalities in the osteocartilaginous and extraosseous (articular or periarticular components such as ligaments, tendons, and menisci; the muscles and the arteries) structures. Abnormalities were seen in all patients. Osteocartilaginous abnormalities in the patients with longitudinal deformities included abnormal distal femoral epiphyses, abnormal proximal tibial physes, hypertrophied and dislocated proximal fibular epiphyses, unsuspected fibular and tibial remnants, and absence or coalition of the tarsal bones. No osteocartilaginous abnormalities were seen in the patients with congenital constriction bands. Articular abnormalities about the knee in patients with either form of hemimelia included absent cruciate ligaments and menisci, dislocated or absent cartilaginous patellae, absent patellar tendons, and abnormal collateral ligaments. All but one limb imaged had absent or attenuated muscle groups. Of the nine MR arteriograms performed at the level of the knee, eight were abnormal. The normal popliteal trifurcation was absent or in an abnormal location. We conclude that MR imaging of children with congenital lower extremity deformities shows many osteochondral and extraosseous abnormalities that are not depicted by conventional radiography. This information can help to plan early surgical intervention and prosthetic rehabilitation.Presented at the 1994 annual meeting of The Society for Pediatric Radiology.     

Stump entrapment of the anterior cruciate ligament in late childhood and adolescence

Displacement of a portion of the torn anterior cruciate ligament (ACL) into the intercondylar notch can cause a focal fibrotic reaction similar to that seen following ACL reconstruction. This displacement, which can result in locking or limitation of knee extension, is termed stump entrapment and is described in adult MR imaging literature. We present a pictorial essay of the etiology and appearance of stump entrapment on MR imaging of the knee in an older child and adolescents and review the significance of this finding.     

The patellofemoral joint: do age and gender affect skeletal maturation of the osseous morphology in children?

Background

The osseous morphology of the patellofemoral joint is an independent factor that affects the biomechanics of patellofemoral instability.

Objective

The purpose of this study is to determine age- and gender-related differences in the osseous morphology of the patellofemoral joint in children during skeletal maturation.

Materials and methods

This study was approved by the institutional review board and was HIPAA-compliant. We included 97 children and young adults (age range 5–22 years; 51 girls and 46 boys, mean ages 14.3 years and 13.7 years, respectively). We studied 1.5-T knee MR exams, measuring the osseous morphology of the patellofemoral joint (lateral trochlear inclination, trochlear facet asymmetry, trochlear depth, patellar height ratio, tibial tubercle-trochlear groove distance, and lateral patellofemoral angle) for each MR exam. We compared measurements to published values for patellofemoral instability. Physeal patency (open or closing/closed) was determined on MR. We assessed the associations between MR osseous measurements and gender, age and physeal patency using Wilcoxon rank sum test and least square means regression models.

Results

The osseous patellofemoral joint morphology measurements were all within a normal range. There were no significant correlations between MR osseous measurements and age, gender or physeal patency.

Conclusion

During skeletal maturation, age and gender do not affect the osseous morphology or congruency of the patellofemoral joint.     

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.