Anatomy
of Back
Ageing Changes in the Spine.
As people age certain changes occur in the tissues throughout the body.
Changes in the intervertebral discs
The degenerative effects of ageing can weaken the annulus fibrosus due to wear and tear. The number of elastic
fibers decrease and the collagen fibres increase. The water content of the nucleus decreases with age and the disc becomes less resilient and less efficient for mechanical functions. The end plates become weak Weight bearing, force transmission and shock absorbing capacities and decreased. Degenerative changes decrease disc height and increase the risk of rupture of the outer casing of annulus
fibrosus. If the outer casing ruptures, the central contents of the disc protrude out of the disc. This is known as disc herniation or prolapsed intervertebral disc or slipped disc.
There are three phases in the degenerative process of the discs
Dysfunctional phase : This phase is characterized by tears or fissures in the outer annulus. End plates also get affected which disrupts the nutrition to the disc. These changes result from repetitive trauma
Unstable phase : This phase is characterized by multiple annular tears, internal disc disruption, and loss of disc height. This phase results from the progressive loss of the mechanical integrity of the vertebral joint complex.
Stabilization phase : In this phase there is further narrowing of the disc space, end plate destruction and disc fibrosis.
Changes in the vertebra
Vertebrae are connected to each other by joints which enable various spinal movements. The bony surfaces which are in contact with each other are coated with cartilage. Cartilage is a special type of connective tissues that provides a self-lubricating, low friction gliding surface. Joint degeneration causes loss of cartilage and formation of osteophytes (e.g. bone spurs). Osteophytes can press the nerve roots or compromise blood supply to the vertebra. These changes are also known as osteoarthritis or degenerative joint disease.
Changes in the ligaments and muscles.
Ligaments are band s of fibrous tissues connecting spinal structures ( e.g. vertebrae) and protect against the extremes of motion. Degenerative changes cause ligaments to lose some of their strength. The main spinal ligament may thicken and / or buckle behind, toward the spinal cord membrane, and cause narrowing of the spinal canal.
The muscles become stiff and there is decrease in their strength. The functional efficiency of the muscles is reduced with aging.
The above changes lead to altered biomechanics of the spinal column. Mobility of the spinal column reduces as one grows older. The spine is unable to bear unnatural stress and strain. As the lumbar spine carries more weight, therefore, when degenerative forces compromise its structural integrity it becomes more susceptible to stress fractures, disc
prolapse, degenerative joint disease and osteoporosis. These changes often affect the lumbar spine in people over the age of 40. Usually more than one vertebrae are involved.
