Imaging of Pediatric Growth Plate Disturbances

Abstract

The growth plates, or physes, are visible on virtually all images obtained in skeletally immature children. The proper function of these growth plates depends on an intricate balance between chondrocyte proliferation, which requires nourishment from the epiphyseal vessels, and chondrocyte death, which requires the integrity of the metaphyseal vessels. Therefore, injury to the growth plate (ie, direct insult) or vascular compromise on either side of the growth plate (ie, indirect insult) can cause growth plate dysfunction. Direct growth plate insults occur most commonly with Salter-Harris fractures, and injuries that allow the transphyseal communication of vessels are at a higher risk for subsequent transphyseal bone bridge formation. Indirect insults lead to different sequelae that are based on whether the epiphyseal blood supply or metaphyseal blood supply is compromised. Epiphyseal osteonecrosis can result in slowed longitudinal bone growth, with possible growth plate closure, and is often accompanied by an abnormal secondary ossification center. In contrast, the disruption of metaphyseal blood supply alters endochondral ossification and allows the persistence of chondrocytes within the metaphysis, which appear as focal or diffuse growth plate widening. Imaging remains critical for detecting acute injuries and identifying subsequent growth disturbances. Depending on the imaging findings and patient factors, these growth disturbances may be amenable to conservative or surgical treatment. Therefore, an understanding of the anatomy and physiologic features of the normal growth plate and the associated pathophysiologic conditions can increase diagnostic accuracy, enable radiologists to anticipate future growth disturbances, and ensure optimal imaging, with the ultimate goal of timely and appropriate intervention. RSNA, 2017.

Maturation-Related Changes in T2 Relaxation Times of Cartilage and Meniscus of the Pediatric Knee Joint at 3 T

“…Our study confirms that identical decreases in cartilage T2 relaxation time values with increasing age and skeletal maturity occur on all articular surfaces of the pediatric knee joint and are not influenced by the magnetic field strength of the MRI scanner. The decrease in cartilage T2 relaxation time values with increasing age and maturation reflects a combination of normal physiologic increase in collagen content and organization [16] and the loss of the acrophysis (growth plate cartilage of the secondary ossification center) and unossified epiphyseal hyaline cartilage [17–19, 25]. Structurally, juvenile cartilage, which develops with age in response to mechanical loading, has a less organized zonal pattern of collagen fibrils [26].…”

Comparison of reliability of magnetic resonance imaging using cartilage and T1-weighted sequences in the assessment of the closure of the growth plates at the knee

“…The cartilage of the growth plate is of interest in any process that may affect its development and result in short stature, such as fractures (Salter–Harris), osteomyelitis, osteonecrosis, and dysplasia. 5 – 7 Forensic medicine has raised interest in the assessment of the growth plate to determine the age of athletes, 8 – 12 and more recently to assess the age of refugees lacking age documentation. 13 Different MRI sequences and rating scales have been used for grading the growth plate related to age, 9 , 14 – 17 but there is yet no consensus as to the most reliable approach.…”

Imaging of Pediatric Lower Limb Sports Injuries

“…In the metaphysis, osteoblasts convert the calcified cartilage into bone, resulting in longitudinal bone growth. 15,16 Injuries to the epiphysis, physis, or metaphysis can lead to disruption of this cascade and thus growth deviations. 14,15 Disturbance of the epiphyseal artery branches leads to abnormal development of the secondary ossification centers, slowed longitudinal growth, and bridge formation.…”

“…15 The physis is thought to be two to five times weaker than the surrounding matured skeleton, making it more prone to injuries than the surrounding tissue. 15,17 Both acute traumatic and overuse injuries of the physis can occur. Acute injuries of the physis are often classified according to Salter and Harris.…”