Topik kedelapan perkuliahan Perancangan Sistem Kerja & Ergonomi adalah tentang Biomekanika Bagian ketiga membahas mengenai gangguan otot rangka atau musculoskeletal disorder mencakup prevalensi, jenis-jenis WMSD, faktor resiko, cara mengidentifikasi dan cara pencegahan yang dilengkapi studi kasus

1. 8.3 Work-related Musculoskeletal
Disorder (WMSD) /
Gangguan Otot Rangka
Auditya Purwandini Sutarto, Ph.D
Part 3 BIOMEKANIKA

2. Learning Outcomes
1. Memahami konsep dasar biomekanika sebagai bagian
dari analisis suatu sistem kerja
2. Memahami konsep manual handling
3. Menentukan beban kerja manual sesuai rekomendasi
4. Memahami berbagai jenis gangguan otot rangka (work
musculoskeletal disorder/WMSD)
5. Melakukan identifikasi faktor resiko terjadinya WMSD
6. Melakukan perbaikan perancangan sistem kerja untuk
mengurangi terjadinya cedera

3. TOPIK
 Fakta dan Data tentang WMSD
 Penyebab WMSD
 Tipe-tipe WMSD
 Faktor Resiko WMSD
 Penilaian WMSD
 Perbaikan Posisi/Teknik dan Penggunaan Alat Bantu
 Studi Kasus

4. FAKTA DAN DATA TENTANG WMSD

5. Keluhan Otot Rangka/Muskuloskeletal
 Kontributor utama penyebab kecacatan di dunia dengan nyeri tulang
belakang (low back pain) menjadi penyebab nomor satu di dunia
 Tidak hanya menimpa usia tua namun merata sepanjang usia. Antara 1
dalam 3 orang atau 1 dalam 5 orang (termasuk anak-anak) mengalami
kondisi nyeri muskuloskeletal
 Pergerakan dan ketangkasan terbatas signifikan sehingga berakibat
pada pensiun atau berhenti kerja lebih awal yang selanjutnya
mempengaruhi kesejahteraan seseorang dan mengurangi
kemampuannya terlibat dalam aktivitas sosial
 Keluhan otot rangka mengakibatkan nyeri yang menduduki proporsi
terbesar untuk nyeri yang tidak disebabkan kanker.
 Keluhan muskuloskeletal berkaitan erat dengan depresi dan peningkatan
resiko masalah kesehatan kronis lainnya
WHO

6. Indonesia .... WMSD in numbers
Survei Departemen Kesehatan di 12
kabupaten pada 9.482 pekerja menunjukkan
sekitar 40,5% penyakit yang diderita pekerja
berhubungan dengan pekerjaan
Gangguan muskuloskeletal (16%)
Gangguan kardiovaskular (8%)
Gangguan saraf (5%)
Gangguan pernapasan (3%)
Gangguan THT (1.5%)

7. Penyebab WMSD
1. Kelelahan dan keletihan terus menerus yang
disebabkan oleh frekuensi atau periode waktu yang
lama dari usaha, otot yang dihubungkan dengan
pengulangan atau usaha yang terus menerus dari
bagian tubuh yang sama meliputi posisi tubuh yang
statis .
 Kata kunci: frekuensi, durasi, besar gaya, repetisi, terus-
menerus/kontinu, statis
2. Kerusakan tiba-tiba yang disebabkan oleh aktivitas
yang sangat kuat/berat atau pergerakan yang tak
terduga.

8. Tahapan terjadinya Cedera MSD yang Kronis

9. TIPE-TIPE WMSD

10. Sakit Leher (Neck Pain)
 Peningkatan tegangan otot
atau myalgia, leher miring
atau kaku leher.

11. Low Back Pain (Nyeri Tulang Belakang)
 Low Back Pain (LBP) terjadi
apabila ada penekanan
pada daerah lumbal yaitu L5
dan S1. Apabila dalam
pelaksanaan pekerjaan
posisi tubuh membungkuk ke
depan maka akan terjadi
penekanan pada discus

12. Carpal Tunnel Syndrome (CTS)
 kumpulan gejala yang
mengenai tangan dan
pergelangan tangan yang
diakibatkan iritasi dan
nervus medianus.
 Tangan mengalami sensasi
kesemutan, mati rasa, nyeri,
atau lemah

13. De Quervain’s Tenosynovitis
 Mengenai pergelangan
tangan, ibu jari, dan terkadang
lengan bawah, disebabkan
oleh inflamasi tenosinovium dan
dua tendon yang berasa di ibu
jari pergelangan tangan.
 Terjadi akibat overuse
 Gejala mirip CTS namun tanpa
mati rasa, kesemutan, dan
tanpa nyeri muncul bertahap

14. Thoracic Outlet Syndrome
 Merupakan keadaan yang
mempengaruhi bahu,
lengan, dan tangan yang
ditandai dengan nyeri,
kelemahan, dan mati rasa
pada daerah tersebut

15. Tennis Elbow
 keadaan inflamasi tendon
ekstensor, tendon yang
berasal dari siku lengan
bawah dan berjalan keluar ke
pergelangan tangan.
 Tejadi akibat overloaded,
biasanya Gerakan berulang
pada pergelangan tangan
dan lengan.

16. FAKTOR RESIKO WMSD

17. Faktor Resiko WMSD
Faktor Resiko
Ergonomi
- Gaya
- Repetisi
- Postur
MSD
Faktor Resiko
Individu
- Teknik pelaksanaan kerja buruk
- Profil Kesehatan kurang baik
- Tidak mengenali adanya
tanda bahaya dari awal
Seiring waktu, paparan faktor resiko ini akan
mengakibatkan MSD

18. 3 Faktor Risiko Utama WMSD
1. Pekerjaan yang membutuhkan gaya
kuat (forceful exertion)
2. Pekerjaan dengan repetisi tinggi
3. Postur yang tidak natural (awkward)
yang cukup lama atau berulang

19. 1. Forceful Exertion (1)
A power grip is 5 times stronger
than a pinch grip
=
High hand force

20. Gripping with the whole hand 10 lbs. of weight or force for
more than 2 hours per day
1. Forceful Exertion (2)

21. Pinching with the fingertips 2 lbs. of weight or 4 lbs. of force for
more than 2 hours per day
1. Forceful Exertion (3)

22. Effort required to support
tool weight and keep it
from twisting out of the
hand
Concern: more effort to ‘engage’
the tool?
1. Forceful Exertion (4)

23. 1. Forceful Exertion (5)

24. Tool use example
Working with bent
wrists decreases
grip strength
Use tools that let
you keep your
wrist straight

25. 1. Forceful Exertion (6)
• Lifting 75 lbs. once
per day
• Lifting 55 lbs. more
than 10 times per
day
Heavy Lifting

26. Reducing heavy lifting
 Take smaller loads at
one time
 Use mechanical
assistance -
handtrucks, carts,
hoists, conveyors
 Get help from a co-
worker

27. 2. Repetitive Motions (1)
Highly repetitive if the
cycle time is 30 seconds
or less.
Assembly Task

28. 2. Repetitive Motions (2)
For more than 4
hours per day
Intensive Keying

29. Reducing intensive keying
 Spread keyboard work throughout the day
 Use macros for common functions
 Take stretch pauses
 Improve your posture and move around as much as
possible

30. 2. Repetitive Motion (3)
Lifting more than 10
lbs., more than twice
per minute, for more
than 2 hours per day
Frequent Lifting

31. Reducing frequent lifting
 Use mechanical assistance
 Slide objects instead of lifting them
 Rotate lifting tasks with co-workers if possible

32. 3. Sustained/Frequent Awkward
Posture (1)
Lifting more than 25 lbs. above the shoulders,
below the knees or at arms’ length more than 25
times per day
Awkward Lifting

33. Avoiding awkward lifts
 Store items where you
won’t have to bend or
reach to lift them
 Use ladders to get
items down from high
shelves

34. PENILAIAN WMSD

35. Job Hazard Analysis

36. Hazard Identification
 Observation/Walkthrough survey
 Interview
 Document Review
 Musculoskeletal Pain/Discomfort Survey
 Risks Assessment of Manual Handling Tasks

37. Risk Prioritization Process

38. What and Why Analysis
 Tasks or steps involved
 Body parts affected
 Risk factors
 Frequency/duration of task
 Why is it done this way?
Assess the task
Prevent & Control
 Potential solutions
 Cost of solutions
 Barriers

39. Ergonomics Checklist

40. Effectiveness
Personal
control
Bodymechanics
Personal protective
equipment
Job organization
Equipment or Engineering
Ergonomics Solution

41. Strategi Mengurangi Resiko WMSD
1. Minimize required hand forces
 design for power grip
 keep handle diameters > 1.5"
 use tool balancing
2. Minimize postural deviations
 keep hand and forearm aligned
 shape the tool to match the task
 change work piece orientation

42. Strategi Mengurangi Resiko WMSD
3. Minimize Repetition
 allow for tissue recovery and circulation
 rotate workers among tasks
 job enlargement
4. Design Work Practices
 train workers to rest (esp. hands)
 stretching exercises or warm-up
 allow for slow-down with gloves
5. Recognize that these strategies will likely increase
productivity in the long run

43. PERBAIKAN POSISI/TEKNIK DAN
PENGGUNAAN ALAT BANTU

44. Proper Technique (1)

45. Proper Technique (2)

46. Proper Technique (3)
Which tool shape
is best??
Depends on: location,
orientation, task, etc.
Wrist Posture

47. Use Turntable
Table with a turntable inset Turntable on a cart

48. Raise the Worker
Use a step stool Use portable steps Use portable waveform

49. Raise or Lower Work Surface
Provide variable-height work surfaces Stack pallets to create a higher work surface.

50. Support the Container

51. Wear Gloves, Provide Clamp-on Handle

52. Use Hand Truck
This specialty hand truck
with brakes will allow more
control when heavy loads
are on inclines
Another type of hand truck
converts to four wheels for
moving unstable loads

53. Use Hand Pallet Truck, Stacker
For unstable pallet
loads, wrap straps
around the load.
This stacker is well suited for
moving loads up to 3,000
pounds for short distances.

54. Use a Conveyor, Slide, or Chute
An expandable skate-wheel
conveyor is portable and
excellent where work needs
to have a flexible layout.
Use slides or chutes to do the
work if containers are always
moving in one direction.

55. STUDI KASUS

56. Isu: Repetitive Motion
 The mobile robot following
magnetic guide tapes on the floor
is used for carrying the PCB part
trolley, resulting in time, manpower
and space savings within the PCB
assembly line
 To provide the PCB components,
the employee repetitively had to
carry the trolley from the
warehouse to assembly lines: The
trolley was transported more than
50 meters (8 cycles per hour, 400
meters in total)
Before After

57. Isu: Repetitive Motion and Awkward Posture
 To pick up components, the employee
repetitively leaned forward and
reached his arm above the shoulder.
He also often moved the part bins from
the floor to a chest height stand.
 The rotating mechanism allows
the employee to keep a more
neutral posture for easy access
to components and storage
bins
Before
After

58. Isu: Prolonged Standing
 The assembly-line employees
stood for long periods on the
same spot and thus could not
have chances to move around
and have a seat at the
workstation.
 With back support, footrest and
stable design, this in-house made
chair can prevent the employees
from fatigue from long period of
standing on the floor.
Before After

59. Referensi
 https://www.cdc.gov/niosh/docs/2014-131/pdfs/2014-131.pdf
 https://ergo-plus.com/wp-content/uploads/Ergonomic-Risk-Factors.pdf
 https://www.dosh.gov.my/index.php/competent-person-
form/occupational-health/regulation/guidelines/ergonomic/2959-
guidelines-for-manual-handling-at-workplace-2018/file
 https://www.who.int/news-room/fact-sheets/detail/musculoskeletal-
conditions