Paediatric Knee Radiographs: Normal Appearances of the Knee Joint in the Growing Patient

Transcription

1 Paediatric Knee Radiographs: Normal Appearances of the Knee Joint in the Growing Patient Poster No.: P-0124 Congress: ESSR 2015 Type: Educational Poster Authors: C. Chisholm, D. Mak, M. Thyagarajan; Birmingham/UK Keywords: Education and training, Education, Plain radiographic studies, Pediatric, Musculoskeletal joint DOI: /essr2015/P-0124 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 25

2 Learning objectives Knowledge of the plain radiograph appearances of the paediatric knee joint at different stages of development. Background Ossification in the knee joint in particular the patella in children can lead to confusing appearacnes on plain radiograph. This poster will outline the normal ossification pattern in the knee joint through childhood and adolescence and highlight any normal variants that can mimic pathology. Imaging findings OR Procedure Details Ossification of the femur, tibia, fibula and patella is a process that starts in utero and continues through to the age of 18. Fig. 1: AP and lateral knee radiographs of a 6 month old child demonstrating ossification centres of the distal femur and proximal tibia. Note that there is also Page 2 of 25

3 metaphyseal beaking of the medial aspect of the tibia which may be confused with a metaphyseal corner fracture. The patella has not yet ossified at this age. References: - Birmingham/UK The femoral shaft begins ossification at 8 weeks in utero. The distal femur then begins to ossify at 3-6 months (Fig. 1 on page 13). At birth the distal femoral epiphysis is in a transverse plane and as children start to walk it is exposed to shearing forces which cause the physis to develop an undulating appearance. The femur continues to grow until 1 the distal femoral physis fuses at years in girls and years in boys. Fractures through the epiphysis or physis are described using the Salter Harris classification (Fig. 2 on page 13), and any fracture through the physis can cause growth disturbances. Page 3 of 25

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5 Fig. 2: AP knee radiograph demonstrating a Salter Harris type 4 with a fracture of both the epiphysis and metaphysis crossing the growth plate. References: - Birmingham/UK The patella begins to ossify at the age of 3-5 years which can lead to confusing appearances (Fig. 3 on page 15). The patella has between 1-3 ossification centres, which enlarge rapidly. As the ossification centres enlarge they often have irregular borders and accessory ossification centres are most common in the superolateral aspect of the patella (Fig. 7 on page 18). These accesory ossfication centres are the cause of bipartite patella and may easily be confused for fractures or actual bipartitie patella 2 in both the adult and paediatric patient (Fig. 8 on page 20). The patella finally fuses in late adolescence. Figures 3-6 demonstrate normal paediatric knee radiographs at varying ages. Fig. 3: AP and lateral knee radiograph of a 3 year old child demonstrating early appearance of an ossifying patella. References: - Birmingham/UK Page 5 of 25

6 Fig. 4: AP and Lateral knee radiographs of a 6 year old demonstrating further ossification of the patella, and undulating distal femoral epiphysis. References: - Birmingham/UK Page 6 of 25

7 Fig. 5: AP and Lateral radiographs of a 12 year old child demonstrating further ossification of the patella. The proximal tibial ossification centre can also be seen on the lateral view which develops as the tibial tuberosity. References: - Birmingham/UK Page 7 of 25

8 Fig. 6: Lateral and AP radiographs of a 15 year old child - the physes can be seen to have started fusing. Also note the presence of the fabella, an accessory ossicle which, is usually found in the lateral head of the gastrocnemius muscle. References: - Birmingham/UK Sindig Larsen-Johansson disease is a chronic traction injury of the osteotendinous junction affecting the inferior pole of the patella and proximal aspect of the patella tendon in children (Fig. 9 on page 20). Patella sleeve avulsion fractures also affect the inferior pole of the patella (Fig. 10 on page 21), and typically affects patients between the ages of 8 and 12. Both Sindig Larsen-Johansson and patella sleeve avulsion may be seen as a small bony fragment at the inferior pole of the patella. Page 8 of 25

9 Fig. 9: Lateral knee radiograph of a 12 year old child demonstrating Sindig-LarsenJohansson syndrome - there is a beaked appearance of the inferior pole of the patella. The proximal tibial ossification centre is also seen. References: - Birmingham/UK Page 9 of 25

10 Fig. 10: Lateral radiograph of a patella sleeve avulsion fracture, with overlying plaster of paris. References: - Birmingham/UK Page 10 of 25

11 th Ossification of the tibia begins about the 7 week of fetal life and starts at a central ossification centre and gradually extends towards the extremities each of which have their own ossification centre. The centre for the upper epiphysis appears around 34 weeks nd gestation and the lower epiphysis appears in the 2 year of life. The medial malleolus forms from its own ossification centre. Later at around the age of 8 a second proximal ossification centre appears which goes on to form the tibial tuberostiy and fuses around the age of 17 (Fig. 11 on page 22). Both of these secondary ossification centres can be mistaken for fractures (Fig. 12 on page 23). The distal physis becomes fully fused 1 around the age of 18 and the proximal physis slightly later at 20. Fig. 11: Horizontal beam lateral knee radiograph of an 11 year old showing the ossification centre for the tibial tuberosity. References: - Birmingham/UK Page 11 of 25

12 Fig. 12: Lateral knee radiograph demonstrating Osgood Schlatters disease. References: - Birmingham/UK Page 12 of 25

13 th As with the femur and tibia the fibula begins ossification in the 8 gestational week with 3 growth centres, one central and on at either end of the bone. The distal epiphysis begins to calcify at the end of the second year and the proximal epiphysis calcifies slightly later 1 around 4 years of age. Closure of both the growth plates occurs in the early 20s and should not be mistaken for avulsion fractures. Images for this section: Fig. 1: AP and lateral knee radiographs of a 6 month old child demonstrating ossification centres of the distal femur and proximal tibia. Note that there is also metaphyseal beaking of the medial aspect of the tibia which may be confused with a metaphyseal corner fracture. The patella has not yet ossified at this age. Page 13 of 25

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15 Fig. 2: AP knee radiograph demonstrating a Salter Harris type 4 with a fracture of both the epiphysis and metaphysis crossing the growth plate. Fig. 3: AP and lateral knee radiograph of a 3 year old child demonstrating early appearance of an ossifying patella. Page 15 of 25

16 Fig. 4: AP and Lateral knee radiographs of a 6 year old demonstrating further ossification of the patella, and undulating distal femoral epiphysis. Page 16 of 25

17 Fig. 5: AP and Lateral radiographs of a 12 year old child demonstrating further ossification of the patella. The proximal tibial ossification centre can also be seen on the lateral view which develops as the tibial tuberosity. Page 17 of 25

18 Fig. 6: Lateral and AP radiographs of a 15 year old child - the physes can be seen to have started fusing. Also note the presence of the fabella, an accessory ossicle which, is usually found in the lateral head of the gastrocnemius muscle. Page 18 of 25

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20 Fig. 7: AP knee radiograph of a 12 year old demonstrating a bipartite patella; the secondary ossification centres can be seen in the superolateral aspect of the patellae. Fig. 8: AP radiograph of an adult patient demonstrating a fractured patella. Page 20 of 25

21 Fig. 9: Lateral knee radiograph of a 12 year old child demonstrating Sindig-LarsenJohansson syndrome - there is a beaked appearance of the inferior pole of the patella. The proximal tibial ossification centre is also seen. Page 21 of 25

22 Fig. 10: Lateral radiograph of a patella sleeve avulsion fracture, with overlying plaster of paris. Page 22 of 25

23 Fig. 11: Horizontal beam lateral knee radiograph of an 11 year old showing the ossification centre for the tibial tuberosity. Page 23 of 25

24 Fig. 12: Lateral knee radiograph demonstrating Osgood Schlatters disease. Page 24 of 25

25 Conclusion Knowledge of the order and ages of ossification is important in accurate interpretation of the paediatric knee radiograph to prevent misdiagnosis and inappropriate intervention. References 1. Ryan S, McNicholas M, Eustace S. Anatomy for Diagnostic Imaging. 2. Saunders Ltd. 3 Edition Ogden JA. Radiology of postnatal skeletal development. X. Patella and tibial tuberosity. Skeletal Radiol. 1984;11(4): rd Personal Information Dr Cass Chisholm, Radiology ST3, West Midlands Deanery. Dr Davina Mak, Radiology ST3 West Midlands Deanery. Dr Manigandan Thyagarajan, Radiology Consultant, Birmingham Childrens Hospital. Page 25 of 25