17 Land Based Rehabilitation and the Aging Spine

Before focusing on the rehabilitation essentials, we will dedicate some time to reviewing the pathophysiologic basis of the degenerative spine, as has been elegantly described by Kirkaldy-Willis.¹ A thorough understanding of spinal anatomy and the process of degeneration will better equip us to grasp the focus of rehabilitation exercises tailored for specific pathologic findings in the degenerated spine. Comorbidities are a significant factor influencing the shape and depth of rehabilitation, therefore it is necessary to review common comorbidities encountered when determining a rehabilitation program, and how to adjust it based on these confounding factors. Finally, before reviewing the essential core stabilization exercises, we would like to touch on the normal physiology involved in stabilizing the spine. With this background, we can better understand the kinematics and kinesiology of the exercises reviewed.

The “Degenerative Cascade”

The spine is dynamic and is constantly modeling and remodeling, a process greatly influenced by the physical stresses placed upon it. These changes can positively or negatively impact neurological status and spinal biomechanics. There are a certain set of conditions associated with degeneration of the aging spine. Most commonly seen disorders include degenerative disc disease, segmental dysfunction or instability, zygapophyseal arthropathy, spinal stenosis, cervical spondylotic myelopathy, and radiculopathy. To better understand these conditions and which therapeutic approach would be most appropriate, we need to understand the pathophysiology of the degenerating spine.

Currently, the most widely accepted theory of intervertebral disc degeneration pathophysiology is a three-stage approach described by Kirkaldy-Willis.¹ Stage I describes the acute pain of an initial insult occurring in the early 20 to 30 years of life. This is the beginning of what Kirkaldy-Willis described as the “degenerative cascade.” Repetitive microtrauma to the vertebral endplates results in ischemic events that can compromise the nutritional and metabolic transport to the disc. This microtrauma may also be responsible for an alteration in proteoglycan content resulting in decreased disc hydration and subsequent load-bearing capacity. Clinically, the patient will present with intermittent and self-limiting pain. However, the pain experienced may be extremely debilitating because of the innervation of the outer third of the annulus by the sinuvertebral nerve.

Stage II, or the instability stage, represents continued disc dehydration and loss of disc height. Increased force transfer to the annulus occurs with the subsequent loss of disc height.¹ This stage occurs later in life, between 30 and 50 years of age, and the patient presents with periods of low back pain which is usually more intense and protracted in duration.

Stage III, known as the stabilization stage, usually occurs in the 60 and older population. There is continued end-stage tissue damage and attempts at repair. Disc resorption leads to disc collapse, endplate destruction, fibrosis, and osteophyte formation. The patient usually presents with symptoms of neurogenic claudication or radiculopathy from central, lateral recess, and/or foraminal stenosis.¹

The Focus of Rehabilitation

Aging is a normal process, and understanding the anatomic and physiological changes that occur with normal aging will allow for optimal rehabilitation. Some age-related bodily changes may be misunderstood and can unnecessarily limit daily activities; however, when designing an exercise program for older adults, the possibility of a latent or active disease process must be taken into consideration. The exercise prescription must be individualized based on the health status and the goals of the individual.

The focus of rehabilitation in the aging population should consist of the following: (1) increasing, restoring, or maintaining range of motion, physical strength, flexibility, coordination, balance, and endurance; (2) recommending adaptations to make the home accessible and safe; (3) teaching positioning, transfers, and walking skills to promote maximum function and independence within an individual’s capability; (4) increasing overall fitness through exercise programs; (5) preventing further decline in functional abilities through education, energy conservation techniques, joint protection, and use of assistive devices to promote independence; and finally, (6) improving sensation, and joint proprioception, and reducing pain.

A conservative approach is usually warranted, considering the patient population’s comorbidities. Any form of aerobic activity should be structured to provide adequate rest and minimal imposition of joint stress.² Initiating resistance training under close supervision with the least amount of resistance can provide significant benefit in the aging population.³ As with younger individuals, functional range of motion is extremely important and all aspects of physical therapy should be preceded by appropriate stretching and warm-up to prevent further injury.

Much has been reported on the appropriate amount of rest a patient with acute back pain should adhere to. What has become clear is that excessive immobility will translate to decreased aerobic capacity, impaired flexibility, loss of muscle strength, and promotion of bone demineralization, all of which will exacerbate and promote further pain and disability.⁴ Ultimately limiting bed rest to a short period proves to be less detrimental than extended periods of bed rest, even in the population of patients who exhibit radiculopathic symptoms.⁵

Pathophysiologic Basis for Rehabilitation

The goal of exercise for the treatment of acute back pain is pain control. Therefore initiating exercises based on which direction of motion either increases or reduces pain will provide more positive outcomes.^6,⁷ Movement into flexion or extension will centralize low back pain and reduce the patient’s symptoms.

Extension-based exercises, or McKenzie exercises, may be effective in reducing discogenic pain ⁸ by alleviating pressure on the posterior annular fibers and thereby altering intradisk pressure,⁹ which will concurrently allow anterior migration of the nucleus pulposus¹⁰ and subsequent decreased tension on the nerve root.¹¹ Contraindications to extension-based exercises include segmental instability, bilateral sensory or motor deficits, large or uncontained herniations, or an increase in radiculopathic symptoms. If the patient responds well to extension exercises and demonstrates centralization of his or her pain, repeated extension posturing while standing and use after sitting or forward bending is stressed. If the patient does indeed have segmental instability, manual blocking of extension at that level can be achieved by the therapist, and the patient can be educated on preventing segmental mobility.

Flexion-based exercises, or Williams exercises, may be effective in decreasing zygapophyseal joint compressive forces, thus alleviating the compressive load to the posterior disc, decompressing the intervertebral foramen, stretching hip flexors and paraspinal musculature, and strengthening core stabilizers, such as the abdominals.¹² Included in flexion-based exercises are pelvic tilts, which can be performed either with bent knees, straight legs, or standing, depending on the comfort level of the patient. These exercises will help decompress the zygapophyseal joint and help mobilize the pelvis for sacroiliac joint dysfunction.

When dealing with patients with idiopathic scoliosis it is widely understood that therapeutic exercises cannot prevent the progression of the curvature; however, there is a clear role for rehabilitation in this setting. The fundamental goal is to prevent the progression of secondary morbidities. Exercises to restore range of motion and strength should begin early. The patient will benefit from exercises that focus on improving trunk posture and alignment, which may prevent the development of a pathological curve. Abdominal and gluteal strengthening helps prevent deconditioning and atrophy, whereas lower extremity hip flexor stretching works well to prevent contractures.¹³

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