summary Spondyloepiphyseal Dysplasia is a rare congenital disorder most commonly caused by a COL2A1 mutation leading to abnormal Type II collagen synthesis. Patients present with dwarfism, flattened faces, scoliosis, and in some cases gait instability as a result of cervical myelopathy. Diagnosis is made radiographically with presence of irregular ossification at multiple epiphyses, flattened vertebral bodies, and thoracic kyphoscoliosis. Flexion and extension radiographs of cervical spine should be performed to evaluate for atlantoaxial instability. Treatment involves a multidisciplinary approach to improve and maintain function. Spinal fusion is indicated in patients with atlantoaxial instability, cervical myelopathy, or progressive scoliosis. Epidemiology Incidence rare Etiology Pathophysiology caused by abnormal synthesis of Type II collagen primarily affects the vertebrae and epiphysis of bone Genetics inheritance pattern autosomal dominant (SED congenita) X linked recessive (SED tarda) random mutation (50% of cases) mutations COL2A1 on chromosome 12 Associated conditions atlantoaxial instability frequent cause of myelopathy in spondyloepiphyseal dysplasia congenita nephrotic syndrome (SED tarda) Classification Two forms of SED exist SED congenita autosomal dominant more severe than SED tarda SED tarda X-linked recessive clinicallly less severe and does not have the lower extremity angular deformities that are present in the congenita form Presentation Symptoms cervical myelopathy due to atlantoaxial instability respiratory difficulty due to respiratory insufficiency secondary to thoracic dysplasia problems with vision due to myopia or retinal detachment hip pain due to coxa varus decreased walking distance due to poor muscular endurance and skeletal deformities Physical exam inspection short stature flatened facies kyphoscoliosis lumbar lordosis coxa vara genu valgum motion decreased ROM of hips waddling gait Imaging Radiographs recommended views AP, lateral, open mouth views of cervical spine AP, lateral views of thoracolumbar spine AP, lateral views of hips alternative views flexion-extension views of cervical, thoracolumbar spine findings cervical spine upper cervical spine instability odontoid hypoplasia or os odontoideum thoracolumbar spine platyspondyly (flattened vertebral bodies) is evident in lumbar spine incomplete fusion of spinal ossification centers end plate irregularities and narrowed intervertebral disk spaces kyphoscoliosis excessive lumbar lordosis hips horizontal acetabular roofs and delayed ossification of the pubis wide Y cartilage coxa vara of varying severity delayed ossification of the femoral head MRI indications cervical instability symptoms of myelopathy findings spinal cord signal changes delayed ossification centers Differential Achondroplasia Diastrophic dysplasia Multiple Epiphyseal Dysplasia (MED) Treatment Nonoperative multidisciplinary rehabilitation indications all patients to improve and maintain function technique should integrate physiotherapy monitor for weakness, increasing spine curvature, worsening hip pain occupational therapist ophthalmologist obtain yearly eye examination pulmonologist monitor for declining lung function orthopaedic surgeon possible bracing for mild scoliosis Operative posterior atlantoaxial fusion indications atlantoaxial instability measuring 8 mm or more myelopathy techniques posterior instrumentation posterior thoracolumbar instrumentation indications spinal scoliosis curvatures >50 degrees techniques distraction spinal rods (younger aged patients) posterior instrumented spinal fusion (older aged patients) valgus intertrochanteric osteotomy indications coxa vara angle <100 degrees progressive coxa vara symptomatic hip arthritis techniques valgus + extension osteotomy may help to decrease an associated hip flexion deformity reconstructive measures may be indicated in patients with subluxation, hinge abduction, or osteoarthritis. open reduction and fixation of proximal femur and acetabulum to treat hip dislocations. Complications Cervical spine instability Spinal deformity including scoliosis, kyphosis, lordosis Ocular abnormalities Hip deformities Degenerative joint disease