Dislocations, ligamentous injuries, epiphyseal detachments, and lesions of the ossification centers are more frequent than fractures in young children [11]. Cervical fractures and craniocervical ligamentous injuries occur more frequently in younger children, while thoracolumbar fractures are more common in older children and adolescents [6].

Intervertebral disc herniation in children is often accompanied by a fracture of the adjacent vertebral end plate. MRI is the imaging of choice to assess intervertebral disc disease [6].

Scheuermann’s disease is an osteochondrosis presenting in late childhood and early adolescence and is characterized by a slowly progressive, fixed or stiff kyphotic deformity of the thoracic or thoracolumbar spine. Radiographic criterion for diagnosis is more than five of anterior wedging of at least three adjacent vertebral bodies [6].

Back pain in children can be caused by various inflammatory and infectious disorders of the spine, spinal cord, nerve roots, meninges, vertebrae, discs, and epidural space [12].

Disorders primarily involving the spinal cord include inflammatory/auto-immune disorders and infectious disorders of bacterial, viral, fungal, or parasitic etiology.

Acute Transverse Myelitis (ATM) is an inflammatory condition associated with rapidly progressive motor, sensory and autonomic dysfunction, most commonly seen between ages 10–19 years [13]. Etiology includes idiopathic forms and entities such as acute disseminated encephalomyelitis (ADEM), neuromyelitis optica (NMO), multiple sclerosis, and ischemic, paraneoplastic, and post-radiation myelitis. MR imaging criteria for myelitis include normal or slightly expanded spinal cord showing diffuse or patchy hyperintensity on T2-weighted images, which may be associated with contrast enhancement. The conus medullaris is frequently involved [14] (Fig. 2a, b). Diffusion weighted imaging typically reveals vasogenic edema.

Infectious discitis and vertebral osteomyelitis are particularly common in children between the ages of 2–12 years and mostly affect males (M:F of 3:1) [15]. It most often results from hematogenous spread. Staphylococcus aureus is by far the most common agent. Spinal tuberculosis is another important cause of back pain and subsequent scoliosis or kyphotic deformity.

CT findings depend on the phase of infection and include cortical erosion, sclerosis, disc hypodensity, reduced disc height and gas within the disc. MR imaging is the gold standard due to its high sensitivity in detecting early abnormal signal within the disc or bone marrow. In the early stages of infection, imaging studies show decreased disc height and abnormal T2 hyperintense signal, with enhancement after contrast administration. With advancing disease, the endplates and vertebrae become T2 hyperintense. Later, infection may spread into the epidural space forming a phlegmon or abscess with thecal sac compression.

In children with symptoms suggestive of infection but negative biopsy and/or cultures, one differential diagnosis to consider in children is Chronic Recurrent Multifocal Osteomyelitis (CRMO), a sterile skeletal inflammation that in the spine typically shows thoracic vertebral involvement with sparing of the intervertebral discs [16].

Vertebral and spinal cord neoplasms are overall rare in children. Suggestive clinical features include persistent and localized back pain, progressive scoliosis, motor weakness, gait disturbance, and paraspinal muscle spasm.

Benign neoplasms of the vertebrae include osteoid osteoma, osteoblastoma, and aneurysmal bone cyst. Malignant neoplasms include Ewing sarcoma, lymphoma, neuroblastoma, Langerhans cell histiocytosis, and metastatic disease. Over 40% of all malignancies affecting the pediatric population arise in the lymphoreticular system [17].

Intrinsic spinal cord tumors include astrocytomas and ependymomas and are most commonly located in the cervical spinal cord [18]. Intradural extramedullary tumors include meningioma, nerve sheath tumors and drop metastasis from CSF spread of malignancy (Fig. 3).

Osteoid osteoma and osteoblastoma are usually located within the lumbar spine involving the lamina or pedicle. Patients typically report back pain at night, relieved by NSAIDs and aspirin. Plain radiographs and CT imaging typically show a radiolucent nidus surrounded by sclerosis, while MR better depicts the surrounding bone marrow edema.

The most frequent tumors of the spinal cord are the pilocytic and anaplastic astrocytomas (60%) and ependymomas (30%). Ependymomas are rare before the first decade, whereas astrocytomas are most common in early childhood. Astrocytomas are most common at the cervicothoracic junction [19]. Neoplastic tissue usually extends beyond the solid enhancing component (Fig. 4). On MRI, astrocytomas are seen as T2 hyperintense lesions with poorly defined margins due to their infiltrative morphology. Ependymomas are slow growing and less infiltrative than astrocytomas, are typically located around the central canal at the cervical spinal cord and tend to compress and displace the adjacent spinal cord tissue. Peritumoral cysts are seen in up to 80% of ependymomas. Ependymomas may be highly vascular with multiple small feedings vessels and intense contrast enhancement. A rim of T2 hypointense signal around the mass, reflecting chronic hemorrhage, is more suggestive of an ependymoma (Fig. 5).

Langerhans cell histiocytosis (LCH) is a disorder secondary to overproduction and accumulation of histiocytes. In the spine, it most commonly involves the thoracic vertebrae and spares the posterior elements. LCH is the most frequent cause of solitary vertebra plana in young people, particularly boys [20]. MRI shows vertebral disc preservation and epidural soft-tissue extension (Fig. 6).