C HILDREN S knees can be studied by double contrast anthrography just as

APRIL, 197$ DOUBLE CONTRAST KNEE ARTHROGRAPHY IN CHILDREN* By ROBERT T. BRAMSON, and TOM W. STAPLE C HILDREN S knees can be studied by double contrast anthrography just as in adults. The paucity ofinformation in the literature regarding pediatric knee arthrography stimulated a review ofour experience in 24 children less than 12 years old. Compared to adults, the incidence and types of arthrographic abnormalities in children are unique. MATERIAL AND METHOD Twenty-four, on about I per cent, of slightly more than 2,500 anthrograms obtamed in the last years (1969-1973), were studies of children to I 2 years of age. The 7 girls and 17 boys underwent either surgical confirmation or clinical follow-up. A review of teenage arthrograms (ages 13 through 19), showed that the indications for arthrography, the lesions found, and the technique were the same as in adults, so that they did not warrant independent study and analysis. TECHNIQUE ST. LOUIS, MISSOURI The anthrographic technique is similar to the double contrast method used in adults. Reassurance and gentle restraint of the patient during injection were sufficient to allow adequate examination of all the children. Neither heavy sedation nor general anesthesia was needed. The knee to be examined was extended and taped to a splint (Fig. i, ii and B). Both knees and the splint were then securely fastened to the x-ray table with adhesive tape. A restraining tape was placed across the child s chest to prevent sitting up during the injection (Fig. i,1 and B). This helped to relax the quadriceps muscle which allowed easier insertion of the needle behind the patella. An assistant reassured the child. It was not necessary for anyone to hold the knee and the sterile field was not disturbed. After sterile preparation and draping, I per cent Lidocaine was injected into the skin just medial to the middle third of the patelba. The tip ofthe needle was positioned behind the middle of the patebla and contrast material and then air were injected. Modifications of the adult injection technique were : (i ) the use of a 23 gauge, I inch needle for injection; (2) only i cc. of 76 per cent meglumine diatnizoate;* and (,) only io to i cc. of air to fill the companabby smaller joint of a child. Air was injected until the radiologist felt mild resistance. Glass syringes were preferred over plastic since they provided a greater sensitivity to resistance during the injection. After the injection, the needle was withdrawn and the straps removed. The knee was flexed 3 times to distribute the contrast material throughout the joint and the study was then continued in the same manner as with an adult knee. 4 RESULTS The normal pediatric knee arthrogram is similar to the adult with only a few exceptions. All the anticular cartilages in the child s knee are thicker than in the adult. The younger the child, the thicker the cartilage. The menisci have an adult configuration but are proportionately smaller (Fig. 2, 1 and B; and 3, 11 and B). Eleven studies were normal and 13 abnormal. No postexamination complications developed. Of the II patients with normal arthrograms, 8 were treated conservatively and are symptom free on clinical follow-up between 6 and 40 months. One 6 year old * Renografin-76, E. R. Squibb and Sons, Inc., P. 0. Box 4000, Princeton, New Jersey. * From the Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri. 838

VOL. 123, No. Double Contrast Knee Arthrography in Children 839 FIG. 4 Restraining tapes are then additionally placed across both knees and the chest. with a normal arthrogram was felt to have a medial collateral ligament strain. A year later his pain and medial collateral ligament tenderness persist. Another patient with a normal arthrogram underwent surgery 3 days later. He had only a hemar- 5 2 inch throsis with normal ligaments and cartilages, while a biopsy of the synovium showed chronic synovitis. A year later his symptoms subsided. The other patient with the normal study has been followed for 2 months and is becomingsymptom free.

840 Robert T. Bramson and Tom W. Staple APRIL, 1975 I - - I strated a projection ofnon-ossifled articulan k cartilage extending from the superior pole of each patebla (Fig. 6). The patient was not operated upon, since this abnormality was not considered the cause of the patient s symptoms. DISCUSSION FIG. 2. (1) Normal medial, and (B) lateral meniscus in a 10 year old child. The articular cartilages are thicker than in the adult. The menisci have an adult configuration. Three types of lesions form the bulk of the pathologic conditions, namely, discoid lateral meniscus, osteochondritis dissecans, and tears of the lateral meniscus. The 3 patients with discoid meniscus all underwent surgery which confirmed the roentgenographic diagnosis (Fig. 4, 44 and B). The symptoms of these 3 patients have resolved following excision of the involved meniscus. The 4 patients with osteochondnitis dissecans have been followed conservatively without surgery and are presently filling in their defects. The torn lateral menisci of 2 patients were confirmed and resected at surgery. These 2 patients are now asymptomatic. One II year old with an anthrographically demonstrated torn lateral meniscus was not operated upon and is now symptom free. One II year old child with a hemangioma of the knee joint has been previously reported (Fig. 5).3h1 One patient with disuse atrophy following derotational osteotomies of the femur had an underdeveloped patella with decreased ossification. Another patient with spondyboepiphyseal dysplasia had palpable masses about the patella in both knees suggesting loose bodies. Anthrography demon- - Congenital or developmental abnormalities constitute over half of the arthro- I. 3.,....... meniscus and (B) lateral meniscus in a 3 year old boy. The articular cartilages of the femur ani tibia are even thicker than those of the patient in Figure 2. The menisci have an adult configuration.

VOL. 123, No. 4 Double Contrast Knee Anthrography in Children 84! graphic abnormalities found in our series. Discoid meniscus, tears of the lateral meniscus, and patellar abnormalities are all secondary to either developmental or congenital factors. The pathogenesis of a lateral discoid meniscus is not entirely settled. Certain authors originally felt that the discoid meniscus was an intrinsic congenital deformity.2 7 #{176}However, Kaplan,5 in an impressive embryologic and comparative anatomy study, concluded that the discoid meniscus was never found in the human fetus, but rather is acquired after birth as a consequence of congenital alteration in the attachment of the posterior horn of the lateral meniscus. The normal lateral meniscus is attached to the tibia at the anterior and posterior aspects of the lateral intencondylar tubercbe Fio.. Discoid lateral meniscus. (A) The apex of the anterior and (B) middle thirds of the meniscus are bulbous. The body of the meniscus extends well into the intercondylar notch. The lesion was surgically confirmed. FIG. 5. Hemangioma of the knee joint. Multilobulated mass occupying the apex of the suprapatellar bursa. and to the femur by the meniscofemoral ligament or the ligament of Wrisberg. According to Kaplan,5 patients who develop a lateral discoid meniscus lack a posterior attachment from the meniscus to the tibial plateau. During knee extension, the postenon meniscus horn dislocates into the intercondylar notch where it is held by the meniscofemorab ligament. As the knee flexes, the meniscus is pulled laterally by the coronary ligaments and popliteus tendon. Therefore, Kaplan5 postulates that the normal horn is trapped between the tibia and the femur and becomes thickened into a discoid meniscus. The discoid meniscus is an uncommon orthopaedic condition, most often discovered in children. It causes a clicking sensation during extension. Occasionally, the knee may lock and some authors feel that the discoid meniscus is more susceptible to tears than a normal meniscus.6 Roentgenographically, in place of the normal triangle, the discoid meniscus free margin bulges into the interarticular space in an oblong fashion. It is often torn and may be fragmented. If severely fragmented, it cannot be differentiated on occasion from an extensive tear with displacement of the

842 Robert T. Bramson and Tom W. Staple APRIL, 197$ - Fio. 6. A cartilaginous spur extends above the upper pole of the patella. This clinically simulated a loose body. free fragment into the intercondylar notch. All 3 patients with a torn menisci had involvement of the lateral meniscus (Fig. 7). This is in contrast to the situation in adults where a majority of tears present in the medial meniscus. The mechanism of meniscus tears has been the subject of extensive research and speculation. Rotational compression forces of the femonal condyle on the menisci during movement and stress result in cartilage tears. Most commonly in the adult, the medial meniscus is torn as the foot is held fixed in place and the femonal condyle rotates externally on the tibia. The normal adult usually has no varus or valgus deformity. On the other hand, children between the ages of 2 and 12 have varying degrees of genu valgus as a normal part of the growth process. After age I 2, this valgus deformity is corrected by normal growth.9 Perhaps the higher incidence of lateral meniscus tears in children is related to altered weight bearing and rotational forces transmitted to the lateral meniscus rather than the medial during the valgoid stage of normal knee development. The diagnosis of osteochondritis dissecans usually is evident on the plain roentgenograms. Arthrography may be of help in demonstrating the condition of the cartilage overlying the necrotic bone or to establish that meniscus injuries may or may not contribute to the symptoms. The anticular cartilage of the femoral condyle can be evaluated to establish whether it merely bulges from the underlying bone, is fractuned and nondisplaced, or presents as a loose fragment in thejoint. It is essential to demonstrate the overlying articular cartilage with a roentgenographic beam projected tangentially to the area of aseptic necrosis. The plain roentgenogram can establish the location of the lesion in relation to the anterior, middle, or posterior third of the condyle. If the lesion is in the middle third of the knee, it will be projected adequately on the standard arthrognaphic spot roentgenograms of the menisci. If it is located posteriorly, a vertical beam can be projected tangential to the posterior third of the femoral condyle when the patient is placed supine and the hip and knee are flexed (Fig. 8). The femoral condyle can be slightly rotated to obtain the maximal projection of the area of osteochondritis dissecans (Fig. 9). FIG. 7. Tear of the lateral meniscus. The meniscus has been separated from the joint capsule. The space between the meniscus and the capsule is not the popliteus tendon bursa.

VOL. 123, No. 4 Double Contrast Knee Arthnography in Children 843 p Fi8 -. i - dissecans. The knee is flexed at 90 degrees and the beam projected along the posterior surface of the femoral condyle. In regard to lateral meniscus tears, our results are similar to those of the extensive study of knee anthrognaphy in children carried out by Stenstrom. 2 Forty-eight per cent of his patients had tears of the lateral meniscus, which is much greaten than in the adult knee. Stenstrom studied patients between ages i and 18 years. A great majority of them were older than age 12 and it was impossible to determine whether an even larger percentage of those patients under age 12 may have had lateral rather than medial meniscus tears. The indications for pediatric knee anthrography differed somewhat from adults. However, in general, arthnography is used to exclude intra-anticular causes of abnormal joint motion. Its value in trauma is demonstrated by the patients in this group with torn lateral menisci. In osteochondritis dissecans, the location of any loose anticular cartilaginous bodies, and the exclusion of any additional lesions becomes important. Gait disturbances in children may be caused by intra-articular lesions, but are more likely to be the result of neunomuscular or growth disturbances such as cerebral palsy, congenital dislocation of the hip, or unequal leg length. Knee locking is a rare occurrence in children and may be caused by extra-articular lesions. We have been impressed by the locking which may be occasioned by fibrosis of the nectus femoris muscle which can prevent full flexion. A year old child recently referred to us for arthrography had in reality fibrosis of the rectus femoris muscle as the result of multiple intramuscular antibiotic injections during treatment for a prolonged severe systemic infection.8

8. Robert T. Bramson and Tom W. Staple APRIL, 197$ REFERENCES FIG. 9. Osteochondritis dissecans (arrows). The articular cartilage overlying the defect is intact. SUMMARY Knee arthrography in the pediatric patient can be performed without heavy sedation on general anesthesia. Lateral meniscus tears predominate oven those of the medial meniscus. The most common lesions found are tears of the lateral meniscus, osteochondnitis dissecans, and lateral discoid meniscus. Congenital on developmental factors apparently contribute to half of the demonstrated lesions. Extra-articular causes should be sought in the very young child with a locked knee. T. W. Staple, M.D., F.A.C.R. Mallinckrodt Institute of Radiology 510 South Kingshighway Boulevard St. Louis, Missouri 63110 I. BUTT, W. P., and MCINTYRE, J. L. Doublecontrast arthrography of knee. Radiology, 1969, 92, 487-499. 2. CAVE, E. F., and STAPLES, 0. S. Congenital discoid meniscus: cause of internal derangement ofknee. Am. 7. Surg., 1941,54, 371-376. 3. FORREST, J., and STAPLE, T. W. Synovial hemangioma of knee: demonstration by arthrography and arteriography. AM. J. ROENT- GENOL., RAD. THERAPY & NUCLEAR MED., I97I, 1z2, 512-516. 4. FREIBERGER, R. H., KILLORAN, P. J., and CAR- DONA, G. Arthrography of knee by double contrast method. Avs. J. ROENTGENOL., RAD. THERAPY & NUCLEAR MED., 1966, 97, 736-747. p 5. KAPLAN, E. B. Discoid lateral meniscus of knee joint, nature, mechanism, and operative treatment. 7. Bone & Joint Surg., 1957, 39-A, 77-87. 6. MIDDLETON, D. S. Congenital disc-shaped lateral meniscus with snapping knee. Brit. 7. Surg., 1936, 24, 246-255. 7. OBER, F. R. Discoid cartilage, trigger knee. Surgery, 1939, 6, 24-30. 8. RASK, M. R., and LATTIG, G. L. Traumatic fibrosis of rectus femoris muscle: report of five cases and treatment. 7.A.M.A., 1972, 221, 268-269. 9. SHOPFNER, C. E., and COIN, C. G. Genu varus and valgus in children. Radiology, I969, 92, 723-732. 10. SMILLIE, I. S. Congenital discoid meniscus. 7. Bone & Joint Surg., 1948,30-B, 67 1-682. II. STAPLE, T. W. Extrameniscal lesions demonstrated by double contrast arthrography of knee. Radiology, 1972, 102, 311-319. 12. STENSTROM, R. Arthrography of knee joint in children. Acta Radiol., 1968, Suppl. 28!.

This article has been cited by: 1. Giovani Krolikowski, Carmen Lice Buchmann de Godoy, Luiz Carlos de Pellegrini, Stella Falkemberg Rausch, Ingrith Aparecida Mazuhy Santarosa, Josaine Cristina da Silva Rappeti, Fabrício Arigony Braga, Kleber Gomes, Daniel Muller, Luciana Brilhante Wolle, Maicon Pinheiro, Rômulo Rotilli Antonov. 2009. Artrografia com meio de contraste positivo e duplo contraste na articulação do úmero de cães. Ciência Rural 39:1, 110-116. [CrossRef] 2. Leon Root, Ulrich C. Liener. 1995. Discoid Lateral Meniscus in Children; Long-Term Follow-up after Excision *. The Journal of Bone and Joint Surgery-American Volume 77:9, 1357-1361. [CrossRef]