Ultrasound elastography, Pediatric rehabilitation, Injection, Rehabilitation therapy, Musculoskeletal exam, Ultrasound-...guided injection, Spasticity management for spinal cord injury, Ultrasound-guided musculoskeletal injection, Spasticity therapy, Neurological rehabilitation, Botox injection, Muscle twitching, Neurologic muscle weakness, Muscular dystrophy, Muscle spasms, Spinal cord injury, Gait unsteadiness, Spasticity, Pediatric trauma, Spina bifida, Neurodevelopmental disorder, Cerebral palsy, Acquired brain disorder, Neuromuscular disorder, Traumatic brain injury