and Introduction Abstract Study Design: Review and reinterpretation of existing literature. Objective: To suggest how intervertebral disc degeneration might be distinguished from the physiologic processes of growth, aging, healing, and adaptive remodeling. Summary of Background Data: The research literature concerning disc degeneration is particularly diverse, and there are no accepted definitions to guide biomedical research, or medicolegal practice. Definitions: The process of disc degeneration is an aberrant, cell-mediated response to progressive structural failure. A degenerate disc is one with structural failure combined with accelerated or advanced signs of aging. Early degenerative changes should refer to accelerated age-related changes in a structurally intact disc. Degenerative disc disease should be applied to a degenerate disc that is also painful. Justification: Structural defects such as endplate fracture, radial fissures, and herniation are easily detected, unambiguous markers of impaired disc function. They are not inevitable with age and are more closely related to pain than any other feature of aging discs. Structural failure is irreversible because adult discs have limited healing potential. It also progresses by physical and biologic mechanisms, and, therefore, is a suitable marker for a degenerative process. Biologic progression occurs because structural failure uncouples the local mechanical environment of disc cells from the overall loading of the disc, so that disc cell responses can be inappropriate or aberrant. Animal models confirm that cell-mediated changes always follow structural failure caused by trauma. This definition of disc degeneration simplifies the issue of causality: excessive mechanical loading disrupts a disc's structure and precipitates a cascade of cell-mediated responses, leading to further disruption. Underlying causes of disc degeneration include genetic inheritance, age, inadequate metabolite transport, and loading history, all of which can weaken discs to such an extent that structural failure occurs during the activities of daily living. The other closely related definitions help to distinguish between degenerate and injured discs, and between discs that are and are not painful.

What is intervertebral disc degeneration, and what causes it?

volves gross structural disruption as well as cell-mediated changes in matrix composition, but there is little evidence concerning which comes first. Comparatively minor damage to a vertebral body is known to decompress the adjacent discs, and this may adversely affect both structure and cell function in the disc. Methods. In this study, 38 cadaveric lumbar motion segments (mean age, 51 years) were subjected to complex mechanical loading to simulate typical activities in vivo while the distribution of compressive stress in the disc matrix was measured using a pressure transducer mounted in a needle 1.3 mm in diameter. “Stress profiles” were repeated after a controlled compressive overload injury had reduced motion segment height by approximately 1%. Moderate repetitive loading, appropriate for the simulation of light manual labor, then was applied to the damaged specimens for approximately 4 hours, and stress profilometry was repeated a third time. Discs then were sectioned and photographed. Results. Endplate damage reduced pressure in the adjacent nucleus pulposus by 25% 6 27% and generated peaks of compressive stress in the anulus, usually posteriorly to the nucleus. Discs 50 to 70 years of age were affected the most. Repetitive loading further decompressed the nucleus and intensified stress concentrations in the anulus, especially in simulated lordotic postures. Sagittal plane sections of 15 of the discs showed an inwardly collapsing anulus in 9 discs, extreme outward bulging of the anulus in 11 discs, and complete radial fissures in 2 discs, 1 of which allowed posterior migration of nucleus pulposus. Comparisons with the results from tissue culture experiments indicated that the observed changes in matrix compressive stress would inhibit disc cell metabolism throughout the disc, and could lead to progressive deterioration of the matrix. Conclusions. Minor damage to a vertebral body end

Mechanical Initiation of Intervertebral Disc Degeneration

We investigated the distribution of compressive 'stress' within cadaver intervertebral discs, using a pressure transducer mounted in a 13 mm diameter needle The needle was pulled along the midsagittal diameter of a lumbar disc with the face of the transducer either vertical or horizontal while the disc was subjected to a constant compressive force The resulting 'stress profiles' were analysed in order to characterise the distribution of vertical and horizontal compressive stress within each disc A total of 87 discs from subjects aged between 16 and 87 years was examined Our results showed that age-related degenerative changes reduced the diameter of the central hydrostatic region of each disc (the 'functional nucleus') by approximately 50%, and the pressure within this region fell by 30% The width of the functional annulus increased by 80% and the height of compressive 'stress peaks' within it by 160% The effects of age and degeneration were greater at L4/L5 than at L2/L3, and the posterior annulus was affected more than the anterior Age and degeneration were themselves closely related, but the stage of degeneration had the greater effect on stress distributions We suggest that structural changes within the annulus and endplate lead to a transfer of load from the nucleus to the posterior annulus High 'stress' concentrations within the annulus may cause pain, and lead to further disruption

‘stress’ distributions inside intervertebral discs: the effects of age and degeneration

AIM OF THE GUIDELINE
The Orthopaedic Section of the American Physical Therapy Association (APTA) has an ongoing effort to create evidence-based practice guidelines for orthopaedic physical therapy management of patients with musculoskeletal impairments described in the World Health Organization’s International Classification of Functioning, Disability, and Health (ICF).320


The purposes of these clinical guidelines are to: 


Describe evidence-based physical therapy practice including diagnosis, prognosis, intervention, and assessment of outcome for musculoskeletal disorders commonly managed by orthopaedic physical therapists


Classify and define common musculoskeletal conditions using the World Health Organization’s terminology related to impairments of body function and body structure, activity limitations, and participation restrictions


Identify interventions supported by current best evidence to address impairments of body function and structure, activity limitations, and participation restrictions associated with common musculoskeletal conditions


Identify appropriate outcome measures to assess changes resulting from physical therapy interventions in body function and structure as well as in activity and participation of the individual


Provide a description to policy makers, using internationally accepted terminology, of the practice of orthopaedic physical therapists


Provide information for payers and claims reviewers regarding the practice of orthopaedic physical therapy for common musculoskeletal conditions


Create a reference publication for orthopaedic physical therapy clinicians, academic instructors, clinical instructors, students, interns, residents, and fellows regarding the best current practice of orthopaedic physical therapy





STATEMENT OF INTENT
This guideline is not intended to be construed or to serve as a standard of medical care. Standards of care are determined on the basis of all clinical data available for an individual patient and are subject to change as scientific knowledge and technology advance and patterns of care evolve. These parameters of practice should be considered guidelines only. Adherence to them will not ensure a successful outcome in every patient, nor should they be construed as including all proper methods of care or excluding other acceptable methods of care aimed at the same results. The ultimate judgment regarding a particular clinical procedure or treatment plan must be made in light of the clinical data presented by the patient, the diagnostic and treatment options available, and the patient’s values, expectations, and preferences. However, we suggest that significant departures from accepted guidelines should be documented in the patient’s medical records at the time the relevant clinical decision is made.

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Low Back Pain Clinical Practice Guidelines Linked to the International Classification of Functioning, Disability, and Health from the Orthopaedic Section of the American Physical Therapy Association

Study Design. A prospective, multicenter trial of the Bagby and Kuslich method of lumbar interbody stabilization for chronic discogenic low back pain, with follow-up evaluation at 3 months, 6 months, and yearly threreafter, with independent radiographic analysis. Objectives. To report the history of development, the surgical technique, and results of the Bagby and Kuslich method when used to manage discogenic pain of the lumbar spine in humans. Summary of Background Data. Disabiling chronic low back pain frequently is resistant to conservative management. The Bagby Basket effectively has fused the equine and baboon spine. The results of biomechanical and animal studies performed over the last 20 years have suggested that a similar but improved design-the Bagby and Kuslich device-would be useful in stabilizing the human spine. Methods. From 1992 to 1995, 947 patients with chronic discogenic low back pain were treated by Bagby and Kuslich interbody fusion in a strict, multicenter, prospective clinical trial by using either the open anterior or open posterior approach. The study involved 42 surgeons at 19 medical centers. The authors of the current report analyzed the fusion rates, pain relief, functional status, and complications occurring in patients who underwent long-term follow-up observation. Results. The Bagby and Kuslich method is safe and effective when compared with methods described in previous reports of posterior and anterior lumbar interbody arthrodesis performed by using bone graft alone. Fusion occurred in 91% of patients at 24 months after-surgery, and pain was eliminated or reduced in 84%. Function was improved in 91%. There were no device-related deaths, cases of major-paralyses, device failures, or deep infections. Conclusions. Carefully selected middle-aged patients with chronic low back pain secondary to degenerative disc disease can be treated effectively and safely by skilled surgeons using the Bagby and Kuslich device for one- and two-level interbody fusion.

The Bagby and Kuslich method of lumbar interbody fusion. History, techniques, and 2-year follow-up results of a United States prospective, multicenter trial.

The tissue origin of low back pain and sciatica: a report of pain response to tissue stimulation during operations on the lumbar spine using local anesthesia.

Cami J. Michael

Papers

The tissue origin of low back pain and sciatica: a report of pain response to tissue stimulation during operations on the lumbar spine using local anesthesia.