Lumbar Stabilization

Excerpt

Spinal stability refers to the spine's ability to maintain its structural integrity and anatomical relationships under normal physiological loading. In the 1990s, 3 interacting systems were proposed to maintain spinal stability; these include:

1. The passive system

   1. This system includes the vertebral bodies, intervertebral discs, zygapophyseal joints, zygapophyseal joint capsules, and spinal ligaments.

2. Active spinal stabilizers

   1. These are the muscles that directly contribute to spine stability by contracting and controlling movement.

3. The neutral system

   1. This network of nerves interacts between these 2 systems.

In a healthy spine, these 3 systems interact to maintain normal function and a pain-free range of motion. Under stress loading of the passive system (vertebrae, discs, ligaments, and joints), the active system (muscles) becomes active and prevents abnormal deformation. The contribution of the passive system to the neutral spine is minimal. Cadaveric experiments demonstrate that when the muscles are removed, leaving only the bones, discs, and ligaments in situ, the spine buckles under a load of 20 lb (9 kg). The neural control subsystem receives input from both the passive and the active subsystems and then directs the spinal musculature to stabilize the spine. The neural system should activate at appropriate times and magnitudes to protect the spine from injury while permitting efficient, controlled movement.

An inability of the active system to maintain the relationship between different elements of the passive system during physiological loading can lead to spinal pain. Based on this, clinical instability can be defined as abnormal displacement within the motion segment under normal physiological loading. In a healthy state, if the 3 systems interact and provide stability, following injury or degeneration of the passive system, the active system must work harder to compensate for the decreased contribution of the passive system. Lumbar stabilization does not exist in a vacuum and must be discussed within the context of lower back pain, its evaluation, differential diagnoses, and treatment options.