Clinical Back Biomechanics and Lifting

clinical utility : clinicians consider the forces acting on or within the human body to

• prevent

• diagnose

• treat (therapy, education)

musculoskeletal injury

we are not allowed to d…

diagnose

examples of lifts, transfers and other forces to consider

repositioning a patient in bed

sustained poor posture while sitting

pushing a heavy equipment cart

lifting a box from the floor to table

why are lifts/transfers bad?

part of a set of risk factors that are associated with low back disorders? (LBD)

LBD’s are …

multifactorial

psychology aspect

pain focus

pain amplification

attitude

sociology aspect

social pressure to make a claim

cultural differences 

physiology aspect

work place design

variability in tissue capacity 

variability in task performance 

psycho-social

perception of social environment 

psycho-physical

perception of physical work environment

stress related

change in tissue properties 

socio-physical

human rights

work practices

based on social pressures 

injuries reported

• psychosocial factors

• malingering 

• pain focus 

tissues damaged

• unreported injury

• company pressure

• psychosocial factors 

factors to consider for LBD clients

personal

psychosocial

workplace/environment related

physical load

what personal risk factors can increase risk of injury 

history of back pain (1.3-18.3)

previous non back injury (3.7)

commuting > 1 hr (2.0)

high body/mass index (1.5-3.2)

low physical fitness (1.8)

smoking (1.4-2.0)

height (1.7)

participation in sports (0.5)

Psychosocial Risk Factors can increase risk of injury

frequent low moods (3.4)

>3 psychological symptoms (3.0)

frequent fatigue/headache (2.3)

low support from superiors (1.8)

job strain (1.7)

work related risk factors that increase risk of injury

job sector (4.3)

working day shift (2.2)

job title/grade (1.7)

working > 35hr week (2.0)

physical load risk factors that can increase risk of injury

twisting and lifting (4.8)

hard physical exertion (1.7-4.3)

frequent manual handling (1.3-3.0)

mixed posture index (1.8-2.3)

lifting with a hoist (2.0)

*vibration 

intervention strategy to reduce physical load risk factors

educate

-worker

-workplace

-therapist

proper lifting technique

traditional lifting directions

bend your knees

hug the load

do not twist

process of injury : overloading meaning 

an excessive load, applied once exceeds tissue tolerance 

process of injury : overuse

a moderate load, applied repeatedly, exceeds tissue
tolerance, cumulative trauma

process of injury: duration

a moderate load, applied continuously, exceeds tissue tolerance 

quantifying lifting loads 

support moment = load moment 

load moment is produced by external forces

Support Moment is produced by internal forces
❑ muscles
❑ ligaments
❑ other soft tissues