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Home > Adult Spinal Deformities (ASDs) – Part I – Spinal Anatomy & Causes

Adult Spinal Deformities (ASDs) – Part I – Spinal Anatomy & Causes

dr carlson scrubbing hands

Jeffrey R. Carlson, MD, MBA, CPE, FAAOS 

Adult spinal deformities (ASDs) can present complex challenges to spine specialists due to their multifactorial causes, clinical presentations, and impact on a person’s quality of life. Individuals with ASDs can have mild discomfort or may experience severe pain, disability, and dysfunction. ASDs encompass a spectrum of structural abnormalities which are characterized by atypical curvature, rotation, and alignment of the vertebral column.  There are various causes, including degenerative changes of the spine, idiopathic and congenital anomalies, traumatic injuries, neuromuscular and iatrogenic factors in individuals aged 18 years and older.

In this multi-article series, I will provide a comprehensive overview of the causes, symptoms, diagnosis, and the most advanced treatments for ASDs. But first, let’s start with a quick review of the anatomy of the spine to aid in your understanding of how it can deform. 

Human Spinal Anatomy starts with the spinal column, comprised of 33 bones in a child, 24 bones in an adult, called vertebrae, that stack one upon another, from the skull to the tailbone. This column is divided into four sections, cervical (neck), thoracic (between the shoulders and upper torso), lumbar (lower back), and sacral (buttocks, tailbone),

In between most of these bones are intervertebral discs, which act as shock absorbers and cushions to help the spinal column bear the weight of the human body, The vertebrae are held together with tendons, ligaments, and muscles, which also help us to bend, move, stand upright, and walk.  There are tiny joints on both sides of most of these vertebral segments called facet joints, which also help us with movement.

The spinal cord, our body’s information superhighway, is protected by this column of bone and runs from the brain to the lumbar level of the spinal column. Nerve roots emerge from the spinal column and run to various limbs and organs throughout the body, carrying and returning nerve impulses, communicating with the brain and running all body systems and processes.

Many Causes of Adult Spinal Deformities are detailed in the list below:

  • Degenerative Changes are age-related degeneration of spinal structures, including intervertebral discs, arthritic facet joints, and ligamentous laxity, which can contribute to the development of ASDs. Disc degeneration leads to loss of disc height, reduced spinal stability, and eventual vertebral malalignment
  • Idiopathic (no-known cause) Scoliosis Progression may be seen in Individuals with a history of adolescent idiopathic scoliosis who experience progression of spinal curvature into adulthood, leading to symptomatic ASDs
  • Genetic Predisposition may also influence the development and progression of certain deformities, although the exact mechanisms remain incompletely understood
  • Traumatic Injuries resulting from high velocity or impact trauma, such as vertebral fractures or spinal cord injuries, can disrupt spinal alignment and predispose individuals to developing ASDs
  • Iatrogenic (illness related to previous medical examination or treatment) Factors: Previous or multiple spinal surgeries, particularly those involving extensive instrumentation and fusion, may contribute to adjacent segment degeneration and subsequent deformity progression
  • Neuromuscular disorders (e.g., muscular dystrophy, cerebral palsy)

In the next installment of the series, I’ll discuss how the spine anatomy should look normally and the different ways that it can manifest deformity.

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