Zygapophyseal joint

• LBP is one of the most common causes of lost or restricted working hours in the industrialized world.

• In general population, the annual incidence is about 5%

• The lifetime prevalence has been estimated at a round 70%

• In subpopulations exposed to high mechanical loads on the low back , the prevalence appears to be even high

• LBP is a phenomenon of all times and all cultures

• The idea of LBP was a consequence of tissue damage due physical injuries (in mid- nineteenth century) in Europe due to high prevalence in railway workers

• At the end of nineteenth century LBP was consider as hysteria due to difficulty to verify the tissue damage objectively .

• In the early twentieth century with advance in orthopaedics LBP was again viewed as physical problem

• discs disorders are the main causes of LBP (protrusions and other injuries) and the compression forces of the spine responsible for this injuries

• When the tissue damage not present the psychosomatic cause may be take attention.

• Up to date the cause of LBP remain elusive in most cases, only in about 10% of the causes of LBP has a specific diagnosis.

• Acute back pain takes less than 6w, subacute 6-12w, chronic LBP more than 12w.

• Only 35% of population reach chronic stage, 60-70% relapsing within 1 year . 10% persist of LBP after 1 year

PREVENTION1- Primary prevention Intervention to diminish the incidence of symptoms

and disorders in health working people (educational back school)

2- secondary prevention Intervention to recovery from the early symptoms and

a reduced risk of recurrence of symptoms and disorders ( educational back school)

• The company perspective is reduction of production loss due to early LBP (reduction of presenteeism)

3- tertiary prevention Intervention to reduce symptoms/disorders

and/or to prevent (further) worsening of disorders including the improvement of the patient’s ability to cope with disabilities resulting from disorders.

• The company perspective reduction of sick leave due to LBP(reduction of absenteeism)

e.g physiotherapy, chiropractic treatment

N.B • organizational ergonomics prevention likes

work groups, job rotation, pre-employment selection, light duty for LBP worker….

• Physical ergonomics prevention likes ergonomic redesign of workstations, equipment , tools selection , lifting devices………..

• individual worker intervention likes training in work models, physical ex and practice, awareness of safety and ergonomics…

Risk factors for LBP

This include1- work-related physical factors2- work-related psychosocial factors3- individual risk factors

3- individual risk factors Previous history of LBP, age, gender, smoking,

obesity, weakness of back and abdominal ms are associated with occurrence of LBP

Injury mechanisms• Age, genetic and mechanical factors are related• General, repeated sub-maximal loading of tissue

could lead to injury• Uncontrolled extreme force as when loss balance• When physical demand are rapidly increased ,

the adaption is faster in ms not spine or the intervertabral disk

Mechanism behind risk factors

• Mechanical loading in manual lifting During lifting , the spine is exposed to high

compression forces, high anterior shear forces, especially the lower lumbar segments and often undergoes considerable deformation in bending, sideward bending and twisting. Compression as well as bending and torsion can cause injury that may lead to LBP.

Determinants of low back load in manual lifting

• Manual lifting could lead to clinically relevant injuries due to the high compression forces and due to high bending stresses occurring when lifting coincides with trunk flexion. Twisting of the trunk during lifting can further increase the probability of injury

• The efficacy of different interventions aimed to reduce the risk of LBP

1. The vertical position of the hand at the initiation of the lift.

2. The horizontal distance between the low back and the hands at the initiation of the lift.

3. The mass of the object

4. The velocity of lifting (slow decrease back load 5% and faster increase 10%)

5. Asymmetry of lifting(increase the spine compression)

6. Lifting style or technique(stoop or/ squat about 10% reduction in back load )

7. Wearing a lumbar support ( 10% decrease in compression forces on the spine )

8. Tilting the object before lifting(tilting reduce back load by 9-17%)

9. One hand versus two handed lifting

10.Team lifting( two people carry the object , the 20% reduction in peak net moment)

11. number of lifts ( fatigue effects)(1-10 lifts need adequate rest in between