Lumbar spondylosis: clinical presentation and treatment approaches - NCBI

Abstract

Low back pain (LBP) affects approximately 60–85% of adults during some point in their lives. Fortunately, for the large majority of individuals, symptoms are mild and transient, with 90% subsiding within 6 weeks. Chronic low back pain, defined as pain symptoms persisting beyond 3 months, affects an estimated 15–45% of the population. For the minority with intractable symptoms, the impact on quality of life and economic implications are considerable. Despite the high prevalence of low back pain within the general population, the diagnostic approach and therapeutic options are diverse and often inconsistent, resulting in rising costs and variability in management throughout the country. In part, this is due to the difficulty establishing a clear etiology for most patients, with known nociceptive pain generators identified throughout the axial spine. Back pain has been termed as “an illness in search of a disease.” Indeed, once “red flag” diagnoses such as cancer and fracture have been ruled out, the differential sources of low back pain remain broad, including the extensive realm of degenerative changes within the axial spine for which radiological evaluation is nonspecific and causal relationships are tentative. We will elaborate on these degenerative processes and their clinical implications. We will further discuss diagnostic approaches and the efficacy of existing treatment options.

Keywords: Low back pain, Spondylosis, Osteophyte, Degenerative disk disease, Intervertebral osteochondrosis

Introduction

Low back pain (LBP) affects approximately 60–85% of adults during some point in their lives]. Fortunately, for the large majority of individuals, symptoms are mild and transient, with 90% subsiding within 6 weeks . Chronic low back pain, defined as pain symptoms persisting beyond 3 months, affects an estimated 15–45% of the population . For the minority with intractable symptoms, the impact on quality of life and economic implications are considerable .

Despite the high prevalence of low back pain within the general population, the diagnostic approach and therapeutic options are diverse and often inconsistent, resulting in rising costs and variability in management throughout the country . In part, this is due to the difficulty establishing a clear etiology for most patients, with known nociceptive pain generators identified throughout the axial spine . Back pain has been termed as “an illness in search of a disease”]. Indeed, once “red flag” diagnoses such as cancer and fracture have been ruled out, the differential sources of low back pain remain broad, including the extensive realm of degenerative changes within the axial spine for which radiological evaluation is nonspecific and causal relationships are tentative

We will elaborate on these degenerative processes and their clinical implications. We will further discuss the diagnostic approaches and the efficacy of existing treatment options.

Tackling the terminology

The terms lumbar osteoarthritis, disk degeneration, degenerative disk disease, and spondylosis are used in the literature to describe anatomical changes to the vertebral bodies and intervertebral disk spaces that may be associated with clinical pain syndromes.

Spinal osteoarthritis (OA) is a degenerative process defined radiologically by joint space narrowing, osteophytosis, subchondral sclerosis, and cyst formation. Osteophytes included within this definition fall into one of the two primary clinical categories . The first, spondylosis deformans describes bony outgrowths arising primarily along the anterior and lateral perimeters of the vertebral end-plate apophyses. These hypertrophic changes are believed to develop at sites of stress to the annular ligament and most commonly occur at thoracic T9–10 and lumbar L3 levels [15]. These osteophytes have minimal effect on intervertebral disk height and are frequently asymptomatic, with only rare complications arising from their close anatomic relationship to organs anterior to the spine

By contrast, intervertebral osteochondrosis describes the formation of more pathological end-plate osteophytes, associated with disk space narrowing, vacuum phenomenon, and vertebral body reactive changes . If protruding within the spinal canal or intervertebral foramina, these bony growths may compress nerves with resulting radiculopathy or spinal stenosis. Moreover, these bony projections may limit joint mobility and invade other organs or tissues . The term “osteoarthritis” suggests pathology limited to bone. Nevertheless, in this context, it has clear implications for the health of neighboring disks and nerve roots.

Comparatively, degenerative disk disease (DDD) refers to back pain symptoms attributable to intervertebral disk degeneration. Such pathologic changes include disk desiccation, fibrosis, and narrowing. The anulus may bulge, fissure, or undergo mucinous degeneration. Also included within the anatomic definition of DDD are defects and sclerosis of the end-plates, and osteophytes at the vertebral apophyses. With these bony changes included in the radiographic description of both OA and DDD, there exists diagnostic overlap between the conditions. As a result, these terms are often used interchangeably in the medical literature to describe similar phenomena.

Spondylosis of the lumbar spine, the subject of this paper, is a term with many definitions. In the literature, it has been utilized in many different contexts, employed synonymously with arthrosis, spondylitis, hypertrophic arthritis, and osteoarthritis. In other instances, spondylosis is considered mechanistically, as the hypertrophic response of adjacent vertebral bone to disk degeneration (although osteophytes may infrequently form in the absence of diseased disks) . Finally, spondylosis may be applied nonspecifically to any and all degenerative conditions affecting the disks, vertebral bodies, and/or associated joints of the lumbar spine. For purposes of this review, we will use this final, broad definition of spondylosis, recognizing the high incidence of coincident degenerative changes, and the dynamic interplay between adjacent disks, vertebra, and nerves that create the clinical pain syndromes within the axial spine and associated nerves.

Epidemiology

Degenerative spine changes are remarkably common in population studies. Symmons’ et al. study of individuals aged 45–64 years identified 85.5% of participants to demonstrate osteophytes within the lumbar spine. O’Neill et al. explored osteophytosis within a UK adult population over age 50 years, finding 84% of men and 74% of women to demonstrate at least one vertebral osteophyte, with increased incidence among individuals with more physical activity, self reported back pain, or higher BMI scores. Despite marked variability within the population, men appear to have more significant degenerative changes than women, both with regard to number and severity of osteophyte formation.

Radiographic evidence of degenerative disease of the lumbar spine among asymptomatic individuals is impressive. MRI imaging in asymptomatic patients over age 60 years reveals disk protrusions in 80% and degenerative spinal stenosis in 20%. A study comparing radiographic evidence of spine degeneration among categories of men who were without pain, with moderate pain, or with severe lower back pain found similar frequency of disk space narrowing and bone spurs among all three groups.

Furthermore, degenerative changes may appear in young individuals without decades of spine loading. Lawrence found 10% of women aged 20–29 to demonstrate evidence of disk degeneration. Lumbar spondylosis, while affecting 80% of patients older than 40 years, nevertheless was found in 3% of individuals aged 20–29 years in one study. The high incidence of degeneration among young and asymptomatic individuals highlights the challenge involved in establishing causality between imaging findings and pain symptoms in affected patients.

Pathogenesis

The high incidence of simultaneous degenerative changes to the intervertebral disk, vertebral body, and associated joints suggests a progressive and dynamic mechanism, with interdependent changes occurring secondary to disk space narrowing.

Intervertebral disks are believed to undergo what Kirkaldy Willis and Bernard first coined a “degenerative cascade”  of three overlapping phases that may occur over the course of decades. Phase I (Dysfunction Phase) describes the initial effects of repetitive microtrauma with the development of circumferential painful tears of the outer, innervated anulus, and associated end-plate separation that may compromise disk nutritional supply and waste removal. Such tears may coalesce to become radial tears, more prone to protrusion, and impact the disk’s capacity to maintain water, resulting in desiccation and reduced disk height. Fissures may become ingrown by vascular tissue and nerve endings, increasing innervation and the disk’s capacity for pain signal transmission. Phase II (Instability Phase) is characterized by the loss of mechanical integrity, with progressive disk changes of resorption, internal disruption, and additional annular tears, combined with further facet degeneration that may induce subluxation and instability. During Phase III (Stabilization Phase), continued disk space narrowing and fibrosis occurs along with the formation of osteophytes and transdiscal bridging 

The spectrum of pathological changes in facial joints and the disk and the interaction of these changes. The upper light horizontal bar represents dysfunction, the middle darker bar instability, and the lower dark bar stabilization

Schneck presents a further mechanical progression, building upon this degenerative cascade of the intervertebral disk, to explain other degenerative changes of the axial spine. He proposes several implications of disk space narrowing. Adjacent pedicles approximate with a narrowing of the superior–inferior dimension of the intervertebral canal. Laxity due to modest redundancy of the longitudinal ligaments enables bulging of the ligamentum flavum and potential for spine instability. Increased spine movement permits subluxation of the superior articular process (SAP), causing a narrowed anteroposterior dimension of the intervertebral and upper nerve root canals. Laxity may also translate into altered weight mechanisms and pressure relationships on vertebral bone and joint spaces believed to influence osteophyte formation and facet hypertrophy to both inferior and superior articular processes with risks for projection into the intervertebral canal and central canal, respectively. Oblique orientations of the articular processes may further cause retrospondylolisthesis, with resulting anterior encroachment of the spinal canal, nerve root canal, and intervertebral canal .

Biochemical research exploring osteophyte formation supports the above process. Osteophyte lipping is believed to form at periosteum  through the proliferation of peripheral articular cartilage which subsequently undergoes endochondral calcification and ossification . Changing weight mechanics and pressure forces as well as alterations in oxygen tension and dynamic fluid pressure appear to be influential factors in osteophyte formation . Mesenchymal stem cells of the synovium or periostium are likely precursors, with synovial macrophages and a milieu of growth factors and extracellular matrix molecules acting as probable mediators in this process 

source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2697338/