EFFECT OF AGING ON SPINE

BY SWETA BHATIA

CONTENTS

• Introduction

• Adult spine

• Aging effect on spine

• Common spinal conditions

• Changes in diagnostic imaging

• Risk factors

• Physiotherapy effect on Aging

• Prevention

• Precautions

SPINE

Aging effect on:

1. Vertebral body

2. IVD

3. Endplate

4. Facet joints

5. Muscle and ligament

6. Biomechanical changes

VERTEBRAL BODY

Trabeculae Cortical

CORTICAL BONE

•Decreased Cortical Thickness

TRABECULAR BONE

Increase risk of fracture due to off axis impact

Increase axial load

Increase anisotropy

Loss of connectivity between trabecula

Increase intratrabecular spacing

Thinning of Trabeculae

Loss of Bone Mineral Density

Normal (top) and osteoporotic (bottom) vertebral bodies.

Decreased structural strength is not only the result of reduced apparentbone density but also

changes in the architecture of the trabecularbone. The increase in bone fragility is due to

replacementof platelike close trabecular structures with more open, rodlike structures. The

more porous cancellous bone appearance is the result of reduced horizontal cross-linking struts

Intervertebral disc

Dehydration and stiffening of annulus

Replace by collagen

Loss of water

Decrease Proteoglycan

Disc collapses and height decreases

Decrease in intradiscal pressure and altered load transmission

Disc disloged gradually from vertebral rim

Cracks in annulus

ENDPLATE

FUNCTION

Increase risk of endplate fracture due to nutrition and hydration of

IVD.

Ossification of endplate

Thinning of endplate

Loss of bone mineral density

FACET JOINT

Functions:

Denudation and ulcerative lesions of articular cartilage, inflammatory

hypertrophy of synovial membrane

Arthritis

Multiplies load on facet

Disk degeneration

FACET JOINT

Stabilize joint but loss of mobility

Degeneration activate remodeling process

Sclerosis of subchondral bone

Osteophyte formation

MUSCLE AND LIGAMENT

FUNCTION PROPERTIES

LIGAMENTS

Decrease IV height

Decrease strength and elasticity of ligament.

Increase crosslinks of collagen

Increase Elastin: collagen

Spinal stenosis

Folding of ligamentum flavum

Increase in thickness due to remodeling

Decrease tension of ligamentum flavum

MUSCLES

Degeneration of sensory end organs

Decrease force generation

Tendon degenerate as ligament

Fatty degeneration in muscle

BIOMECHANICAL CHANGES

1. Creep characteristics of IVD

2. Kinematics of FSU

3. Compressive strength of vertebral

body

4. Stress and intradiscal pressure across

IVD

5. Load sharing

CREEP CHARACTERISTICS OF IVD

Non Degenerative Degenerative

Uneven stress distribution

Attenuates decrease shock absorption

Deforms fast

Load

Viscoelastic property and regain back normal space

Creep slowly

Load

Temporal change in the displacement of an intervertebral

disc under a constant load (i.e., creep) with different

stages of degeneration. As degeneration worsens, two effects are

observed: a) the final displacement increases and b) the rate of

deformation increases significantly, in particular, immediately after

the load is applied

KINEMATICS OF FSU

Non Degenerative Degenerative

IAR and ROM due to ligament, facet, IVD changes lead to hypomobility, hypermobility, immobility or

paradoxical motion

Spontaneous fusion

Decrease in advance IDD

ROM increase in initial IDD

Spread out even out side FSU

Small area in posterior aspect of FSU

Axis of rotation

In a normal FSU, the

instantaneous center of rotation

(COR) stays within a narrow region

in the posterior aspect of the FSU

(shown in the yellow circle; F:

Flexion; E: Extension). In the case

of a degenerated disc, the COR

may vary over a wide area, even

outside the FSU

COMPRESSIVE STRENGTH OF VERTEBRAL BODY

Increase risk of vertebral fracture

Thinning of cortical bone.

Decrease maximal compressive strength at central region.

Decrease bone mineral density

COMPRESSIVE STRENGTH OF VERTEBRAL BODY

Hard to compensate by muscle and ligament alone.

Flexion posture

COG forward

Anterior wedging

STRESS AND INTRADISCAL PRESSURE ACROSS IVD

Decrease tension in annulus, load transfer and compression throughout annulus

Decrease intradiscal pressure

Increase pressure on annulus and loss of height

Nucleus dehydration

Comparison of the stress profiles between a normal and

a degenerated disc. In a normal disc, a plateau in the stress profile

is observed whereas, in the degenerated disc, spikes are seen in

the annular regions and diminished stress profile is observed in the

nucleus pulposus.43 Modified and adapted from McMillan, D.W.,

McNally, D.S., Garbutt, G. & Adams, M.A. Stress distributions inside

intervertebral discs: the validity of experimental “stress profilometry’.

Proc Inst Mech Eng H 210, 81-87 (1996).

Decrease of intradiscal pressure with increasing grade

of disc degeneration. The pressure measurements were taken in

the prone body position. Horizontal and vertical refers to the alignment

of the pressure-sensitive membrane of the pressure sensor.45

Modified and adapted from Sato, K., Kikuchi, S. & Yonezawa, T. In

vivo intradiscal pressure measurement in healthy individuals and

in patients with ongoing back problems. Spine (Phila Pa 1976) 24,

2468-2474 (1999).

LOAD SHARING

Increase loading of annulus and facet joint

Load distribution alter

Bone loss and hypertrophy in facet and pars interartcularis

Increase compressive load on neural arch

Effects of lumbar disc degeneration on compressive

load sharing. In a normal disc, the neural arch resists only 8% of

the applied compressive force, and the remainder is distributed

between the anterior and posterior aspects of the vertebral body.

Disc degeneration forces the neural arch to resist 40% of the

applied compressive force, whereas the anterior vertebral body

resists only 19%

DIAGNOSTIC IMAGING

HOW CAN PHYSIOTHERAPY HELP?

• Cannot Treat Condition But We Can Treat Symptoms And Avoid Complication

• Maintenance Phase And Prevent From Worsening

• After Surgery

• Preventive Physiotherapy

REFERENCES

1. THE AGING SPINE : NEW TECHNOLOGIES AND THERAPEUTICS FOR OSTEOPOROTIC SPINE ( JOSEPH M. LANE , MICHAEL J. GARDNER, JULIE T. LIN, ELIZABETH MYERS)

2. BIOMECHANICS OF AGING SPINE: ( STEPHEN J. FERGUSON, THOMAS STEFFEN)

3. SPINE BIOMECHANICS AND AGE (AKASH AGARWAL, VIKAS KAUL, VIJAY K GOEL)

REFERENCES

4. PATHOPHYSIOLOGY AND BIOMECHANICS OF THE AGING SPINE (MICHAEL PAPADAKIS, GEORGIOS SAPKAS, ELIAS C. PAPADOPOULOS, PAVLOS KATONIS)

5. THE AGING SPINE (NDRNNIGEL KELLOW)

6. AGE ASSOCIATED CHANGES IN INNERVATION OF MUSCLE FIBERS AND CHANGES IN MECHANICAL PROPERTIES OF MOTOR UNITS (LUFF AR)

7. EXERCISE AND PHYSICAL ACTIVITY FOR OLDER ADULTS ( WOITEK J. CHODZKO – ZAIKO , DAVID N PROCTOR)

8. WEB ( PHYSIOPEDIA)

THANK YOU!