2. Definition
Musculoskeletal disorder (MSD) is an injury or disorder of the
muscles, nerves, tendons, joints, cartilage, and spinal disc.
Chronic disease related to manual tasks
Source of significant pain, disability and disadvantage for the
injured person and a substantial burden on modern societies.
Statistics suggest that more than 30% of all occupational
injuries are musculoskeletal injuries associated with manual
tasks (Straker et. al. 2004).
3. Globally, musculoskeletal conditions are one of the leading causes of
morbidity and disability, giving rise to enormous healthcare expenditures and
loss of work (WHO 2003), and reducing the quality of life of affected
employees and their families.
4. Work related musculoskeletal
disorders (WMSD)
Various synonyms of WMSD –
Repeated strain injury
Cumulative trauma disorder
Over use syndrome
Due to repeated straining body tissue and not allowing enough time to heal are
believed to cause progressive discomfort, pain, and ultimately disability to
continue regular work.
5. Cumulative Trauma Cycle
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irritation
to tissue
microtrauma
(small tears)
produces
scar tissueKeeps repeating
as long as
activity continues
results in:
flexibility
strength
function
adhesions
form
adhesions
coalesce
6. Risk Factors for Musculoskeletal
Disorders
Excessive force
Awkward and/or prolonged postures
Repetition
Direct Pressure
Temperature Extremes
Vibration
Non occupational factor : fitness,
mental status, smoking, hormonal
disorder etc 6
7. 7
Excessive Forces
Common risky problems:
• Lifting and carrying
• Pushing and pulling
• Reaching to pick up loads
• Prolonged holding
• Pinching or squeezing
8. 8
Awkward Postures
Common risky postures:
Working overhead
Kneeling all day
Reaching to pick up loads
Twisting while lifting
Bending over to floor/ground
Working with wrist bent
9. 9
Contact Stress/Poorly Designed
Equipment
Common equipment problems to watch
for:
Does not have a good grip
Too heavy
Hard to use
Uncomfortable
Bad condition
Wrong tool/equipment for the job
10. 10
Vibration
Can lead to injury when you are:
Using reciprocating tools
Using grinding or impact tools
Using vibrating tools
Working in or on motorized
vehicles
11. Causes of WRMSD
How does a musculoskeletal injury occur?
Basically, thousands of forceful, awkward and repetitive
movements produce trauma to muscles, tendons and ligaments
which eventually leads to pain, inflammation, swelling and
deterioration of tendons and ligaments.
12. An Activity is Likely to Become an
Injury
When:
You perform the activity frequently
You do the activity a long time
The work intensity is high
There are a combination of factors
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16. Causes
Tennis elbow is a type
of repetitive strain injury,
resulting from tendon overuse and
failed healing of the tendon. In
addition, the extensor carpi
radialis brevis muscle plays a key
role.
17. Occupational classification Lateral epicondylitis may
be provoked by an exercise involving repeated and
forcible extension movements at the wrist. The
following three types of occupational group are
classified respect to elbow stress
Type 1: No or little stress on the elbows ( Driver.
Instructor, Office worker, clerk, security guard).
Type 2: Moderate stress on the elbows (e.g.
inspectors, electricians. repairmen, unpacker,
toolmaker).
Type 3: Heavy stress on the elbows (e.g. Blaster,
driller, polishers, welders, carpenter)
18. Signs and symptoms
Pain tenderness on the outer part of the elbow
(lateral epicondyle)
Pain from gripping and movements of the wrist,
especially wrist extension and lifting movements
e.g. pouring a container of liquid, lifting with the
palm down, sweeping, especially where wrist
movement is required
19. Diagnosis
With the elbow fully extended, the patient feels points of
tenderness over the elbow pain with passive wrist flexion and
resistive wrist extension (Cozen's test).
Pain with Resisted middle finger extension might indicate the
involvement of Extensor Digitorum also.
20. Treatment
Conservative.
Rest, Ice, compression and elevation
NSAID
Physical therapy, occupational therapy,
orthotics or braces may also be useful.
Steroid injections
Laser therapy,prolotherapy,us
21. Counterforce orthosis
Wirst extensor orthosis reduces the overloading
strain at the lesion area.
Orthosis is a device externally used on the limb to
improve the function or reduce the pain.
22. Both eccentric loading and extracorporeal
shockwave therapy are currently being
researched as possible treatments for tendinosis.
Other treatments for which research is on-going
includes Platlet Rich Plasma (PRP), and stem
cell injections.
Operative treatment
23. Golfer's elbow
tendinosis of the medial epicondyle of the elbow.
Tenderness over the origin of the flexor pronator mass
Resisted pronation and/or wrist flexion will reproduce
symptoms in most affected patients
Grip strength is decreased in patients with medial
epicondylitis compared with control subjects, although
the magnitude of impairment is less than that seen in
patients with lateral epicondylitis
24. The pathogenesis of medial epicondylitis parallels
that of lateral epicondylitis, beginning with
repetitive microtrauma to the wrist flexors
originating at their origin on the medial
epicondyle.
The muscles most commonly involved include the
pronator teres and flexor carpi radialis but can
include any of the other flexor.
Seen in overhead throwing sports,or in
occupations requiring repetitive forearm
pronation and wrist flexion eg carpenters
25. Non-specific palliative treatments include:
Non-steroidal anti-inflammatory drugs
Heat or ice
A counter-force brace or "elbow strap" .
Therapy for muscle/tendon reconditioning,
starting with stretching and gradual strengthening
of the flexor-pronator muscles.
Strengthening slowly begin with isometrics and
progresses to eccentric exercises helping to
extend the range of motion back to where it once
was.
26. Distal biceps tendonitis
Diagnosis:
sudden and unexpected forceful extension against
a flexed elbow, or a pop is felt during heavy lifting.
Complete ruptures commonly result in Popeye
deformity in the upper arm.
Flexion and supination of the elbow are painful
and strength is noticed to be decreased in the
affected extremity
Magnetic resonance imaging (MRI) helpful
diagnostic tool for the diagnosis of a partial tendon
rupture
27. Risk factor
More common in male, dominant limb
Smoker,chronic steroid use.
Occupations with repetitive forearm
motion(plumbers,laborers and athletes)
28. Treatment
Partial ruptures and tendinosis can be managed
with nonoperative options and physical therapy,
but early surgical repair is recommended for
complete ruptures with postoperative physical
therapy.
29. Triceps Tendonitis
Triceps tendinosis is a chronic condition stemming
from overuse and repetitive heavy lifting.
Patients routinely describe pain and/or weakness
with activities of elbow extension.
Tenderness to palpation occurs at the triceps
insertion on the olecranon.
In the setting of chronic repetitive injury, plain
radiographs may reveal a traction osteophyte on
the olecranon.
30. Treatment
Nonoperative activity modification, nonsteroidal
anti-inflammatory medications, and physical
therapy for stretching and ROM ex
Operative management, consisting of olecranon
osteophyte excision and triceps repair, is reserved
for refractory cases that fail conservative
management.
31. There are several recommendations regarding
prevention, treatment, and avoidance of
recurrence that are largely speculative including
stretches and progressive strengthening exercises
to prevent re-irritation of the tendon.
33. Olecranon bursitis ( "Smiles' elbow", "elbow
bump", "student's elbow", "Popeye elbow",
"baker's elbow" or "gamer's elbow"),
Characterized by pain, redness and swelling
around the olecranon, caused by inflammation of
the elbow's bursa. This bursa is located just over
the extensor aspect of the extreme proximal end
of the ulna.
34. Bursitis normally develops as a result either of a
single injury to the elbow (e.g., a hard blow to
the tip of the elbow)
Repeated minor injuries, such as repeated leaning
on the point of the elbow on a hard surface.
Job or hobby involves a repetitive movement
(e.g., tennis, golf, or even repetitive computer
work involving leaning on one's elbow)
35. `
Non-surgical treatments
Icing, a firm compression bandage, and avoidance
of the aggravating activity,NSAIDs .
Treatment for more severe cases may
include aspiration of the excess bursa fluid
hydrocortisone injection .
In case of infection, the bursitis should be treated
with an antibiotic.
Surgical treatments
36. Pronator syndrome
Compression of the median nerve in the region of
the elbow or proximal part of the forearm
Pain and/or numbness in the distribution of the
distal median nerve
weakness of the muscles innervated by the
anterior interosseous nerve: the flexor pollicis
longus the flexor digitorum profundus of the
index finger and the pronator quadratus.
37. Causes
The most common cause is entrapment of the
median nerve between the two heads of the
pronator teres muscle. Other causes are
compression of the nerve from the fibrous arch of
the flexor superficialis, or the thickening of
the bicipital aponeurosis.
Jobs requiring repeated pronation or
supination,lifting, carrying,or placing heavy
objects.
38. Clinical signs
Tenderness over the proximal median nerve,
which is aggravated by resisted pronation of the
forearm and resisted middle finger flexion.
The flexor pollicis longus and FDP of the index
finger are weak.
Sensory changes may be found in the first three
fingers as well as in the palm, indicating
impairment of the median nerve proximal to
the flexor retinaculum.
39. Treatment
Anti-infammatory medication
Injection of corticosteroids into the pronator
teres muscle.
Stretching and strengthing ex
Massage therapy
Surgical decompression can provide benefit in
selected cases.
40. Diagnosis
Conduction velocity of the median nerve in the
proximal forearm may be slow but the distal
latency and sensory nerve action potential at the
wrist are normal.
MRI may show denervation atrophy of the
affected muscles
EMG or the MRI are abnormal for the pronator
teres muscle and the flexor carpi radialis, this
implies that the problem is at or proximal to the
elbow
41. Cubital tunnel Syndrome
The cubital tunnel is a channel which allows
the ulnar nerve to travel over the elbow. It is
bordered by the medial epicondyle of the
humerus, the olecranon process of the ulna and
the tendinous arch joining the humeral and ulnar
heads of the flexor carpi ulnaris.
Chronic compression of this nerve is known
as cubital tunnel syndrome, a form of repetitive
strain injury akin to carpal tunnel syndrome.
42.
43. chronic compression or repetitive trauma
Sleeping with the arm folded behind neck, elbows
bent.
Pressing the elbows upon the arms of a chair
while typing.
Resting or bracing the elbow on the arm rest of a
vehicle.
Bench pressing.
Intense exercising and strain involving the elbow.
44. Ulnar nerve entrapment at the medial aspect of
the elbow, causing medial elbow pain and
paresthesias in the ring and little finger.
This occurs through repetitive activity requiring
flexion or extension of the elbow against
resistance.
46. Definition of ergonomics
“Ergonomics is the science and practice of
designing jobs and workplaces to match
the capabilities and limitations of the
human body.”
Simply put:
“fitting the job to the worker”
The goal of ergonomics is to create jobs, tools,
equipment and workplaces that fit people,
rather than making people adapt to fit them.
47. Ergonomic Prevention Approach
Engineering approach – Analyze the job it detail.
Various posture evaluation schemes can be used
for rough estimation of joint deviation,
repetition/duration, and forces involved.
They provide scores for action limit and maximum
limits, by which jobs can be selected for
improvement.
Internal joint forces can be evaluated by EMG,
biomechanical models.
48. Solution approaches are mechanization, job
enlargement, redesign the workstation for
adjustability and better working posture, better
method to do the work to reduce force, duration,
repetition.
Administrative approach – Job rotation, use of
part time workers, exercises, stress reduction.
49. Examples of engineering solutions
Counter balance and suspend hand tools - reduce
static load of holding the tool.
Tilt the work surface - facilitate better posture,
viewing, reach.
Provide hand tools with correct grip
style/diameter/texture – reduce gripping force,
improve wrist posture
Maintain sharpness of the knives – reduce force
required to cut Hand tools are properly
maintained - reduce vibration
50. More of engineering solutions
Use correct work height – better upper body and
hand-arm posture ,Limit reaching motions to
minimum
Lower the work area if shoulders needed to be
lifted
Provide arm rest if elbows are needed to be raised –
reduce static load at shoulder
Consider sitting/standing/sit-stand work posture –
reduce static load in lower back
Arrange workplace to minimize twisting, forward or
lateral bending – reduce harmful posture of torso
Correct viewing angle - minimize static load on
neck muscles, eye strain.
51. Arrange work to avoid unnecessary motions.
Let power tools and machinery do the work.
Spread repetitive work out during the day.
Take stretch pauses
Rotate task with co-workers if possible
Change hands or motions frequently
Reducing repetition
52. Benefits of ergonomics
Ergonomics helps to prevent injuries
Ergonomics has other benefits
Reduced fatigue and discomfort
Increased productivity
Improved quality of work
Improved quality of life
53. Conclusions
Cumulative trauma occurs over time
Applying ergonomics = injury prevention
Understand injury risk factors
Some situations may have little room for improvement, but with
others you have the control to improve:
equipment
work practices
bodymechanics
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