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1 LBP and NIOSH Lifting Equation 陳志勇 IOSH HIVD: 椎間盤突出壓迫神經 The herniation of intervertebral disc(hivd) 1

2 HIVD: 椎間盤突出壓迫神經壓迫神經 ( 法定職業病 ) 在年青人當中引起下背痛甚至導致坐骨神經痛的疾病中, 本病佔很大比例椎間板周邊的纖維環破裂, 中間的髓核向後突出, 即產生局部的下背痛 ( 多只患一側 ) 若壓迫到神經根, 則引起坐骨神經痛 X 光典型的 HIVD 引起的坐骨神經痛, 彎腰最痛, 坐著比站著不舒服剛開始時多半是某一特定動作突然發生背部劇痛, 患者多認是閃了腰, 休息幾天就沒事, 但是以後每次姿勢不對就反覆發生, 終於有一天疼痛由下背部慢慢擴散到臀部, 大腿外或後側, 甚至延伸到下腿或足背或足底部此病症經休息服用止痛藥及接受腰部牽引, 應避免不必要的開刀 (?? 避免工作 ) 脊椎滑脫症脊椎滑脫最常發生在第四五腰椎間, 疼痛部位在後下背部兩側, 大腿, 但很少痛到膝關節以下 Pedicle X 光病人常在久站或走久後就開始痛, 一坐下來或蹲下來疼痛就逐漸消失一般而言, 如不是很嚴重可穿背架, 減少活動, 加強腹肌肌力, 可得長期的效果 ; 如果嚴重, 只有靠手術作脊椎固定術了 2

3 下背痛 : 軟組織傷害軟組織傷害 exposure level 病患, 無法說出自己的病因, 而大多數的病人曾就診於一個以上的醫師, 且常從不同醫師得到不同病因, 甚至 X 光骨髓造影電腦斷層或核磁共振也無法顯示出那裏異常俗稱閃到腰, 拉傷的肌肉常有明顯的壓痛點, 也有肌肉痙攣的現象, 腰部轉動或前側彎常發生誘發性劇痛, 這種的傷害, 不需特別的治療, 只要適當休息或服用幾天的止痛藥, 熱敷或泡熱水澡即會慢慢的好起來椎間盤退化椎間盤退化是一緩慢且具有累積性的, 退化會導致腰椎結構不穩定當腰椎不穩定時, 可能是透過軟組織的共作用來協助穩定與平衡, 更多的共作用力會加重腰椎的受力一般歲的人, 椎間盤退化的比例約在 40-60% 之間一項 MRI 研究發現歲歲歲, 椎間盤退化的發生率約為 34% 59% 93% 除了生理退化, 工作場所中人因工程 / 物理性因素也是導致退化的重要原因 3

4 下背重複性傷害的過程 Assumption 4

5 認識腰椎受力 ( 暴露強度 ) 認識腰椎受力 -- 站姿 Weight (Kg) Height (cm) Low back compression (N)

6 如何坐?? 暴露量測外力是由重力所引起的, 如所搬運的物體重量體重等這些力量必須由身體的肌肉骨骼等組織來承受, 組織為了對抗外力所產生的力稱為內力 ( 如肌肉收縮力 ), 肌肉收縮力與外力最終會作用在關節上內力估算, 必須透過模式, 簡化人體結構來推算例如背部肌肉僅以背直肌代表, 亦即僅有背直肌對抗外力 6

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9 Basic principles for NIOSH Lifting Equation 搬運公式主要在計算可接受之抬舉物重根據流行病學生理學心理物理法與生物力學等四種不同學理而發展生物力學上 : 下背脊椎間 (L5/S1; 第五腰椎與第一薦椎間椎間盤 ) 壓迫力之安全容忍範圍 (<3400N) 9

10 407 lumbar specimens Mean 4.4 KN S.D KN 30%ile 3.4 KN 16%ile 2.5 KN 10

11 人工提舉指引 -- 生理生理上 : 代謝能量速率在一定範圍內 ( Kcal/min) Baseline 50%ile female 40yrs 9.5Kcal/min i.e. 4000/Kcal/day-420min 20yr male 20Kcal/min 50% for < 1hr, 40% for 1-2 hrs, and 33% for 8hrs. 70% for arm predominantly work NIOSH 1991 Lifting Equation RWL=23 (25/H) ( V-75 ) (0.82+(4.5/D) ( A) FM CM RWL = "Recommended Weight Limit" = 23kg HF VF DF FF AF CF LI = "Lifting Index" = WEIGHT / RWL 11

12 GUIDELINE APPLIES TO 1. SMOOTH LIFT (no jerking) 2. TWO HANDED 3. (OLD) SYMMETRIC ( no twisting) 4. MODERATE WIDTH (30" max.) 5. UNRESTRICTED POSTURE 6. (OLD) GOOD COUPLINGS (handles, shoes, flooring) 7. FAVORABLE ENVIRONMENT (temp/ humid/ noise/ light) 水平乘數與起始高度乘數 Horizontal Multiplier HM (25/H) H = 20 + W/2 for V => 25 cm(10 in) H = 25 + W/2 for V < 25 cm (10 in) Vertical Multiplier VM = 1-(.003 [V-75]) 12

13 Factor V FACTOR Factor VERTICAL LOCATION (inches) Factor 0.8 VERTICAL + D FACTOR Factor D HORIZONTAL + VERTICAL DISTANCE (inches) 13

14 Factor 0.8 HORIZONTAL (+) A FACTOR Factor LEFT FOOT A RIGHTFOOT 0.2 LOOKING DOWN o o o o o ASYMMETRY (degrees) 非對稱乘數 Asymmetric Multiplier AM = 1-(.0032A) 旋轉軀幹取物或置物 Based on the results of Psychophysical research: 90 O twisting results in the reduction of MAWL about 30%. 14

15 F r e q u e n c y L ift s / m in F r e q u e n c y M u ltip li e r T a b l e ( F M ) W o r k D u r a t io n 1 H o u r > 1 b u t 2 H o u r s > 2 b u t 8 H o u r s V< 7 5 V 7 5 V< 7 5 V 7 5 V< 7 5 V 7 5 = Coupling Factor Coupling V< 30" V>30" Good Fair Poor

16 Collect Data-Single Task Job Analysis Worksheet Ex 1 Loading Punch Press Stock Single task, a few times per sift A = 0 CM fair once per shift, assuming F < 0.2, Duration < 1 hour reel width 12 in 16

17 Hazard Assessment and Redesign Load 44 lbs > RWL 16.3 / 14.5 lbs, this lift would be hazardous for majority of healthy workers. Redesign Suggestions HM(.44) is the smallest multipliers,.75 for the VM, and.86 for the DM. First, bring the object closer to the worker (increasing HM) Then, lower the destination(vm),... 17

18 Ex 2 Loading Supply Rolls H = 15 in (origin) less than.2 lifts/min for less than 1 hour poor coupling A = 0 18

19 Hazard Assessment and Redesign Load 35 lbs > RWL 28 / 18.1 lbs, this lift would be hazardous for majority of healthy workers. Redesign Suggestions HM (.5,.67) is the smallest multipliers,.85 for the VM, and.9 for the CM. First, bring the roll closer to the worker (increasing HM by reducing the size of roll) Then, raise the height of destination(vm, eg. V=30 in VM from.85 to 1.0, H from 20 to 15 in), improving coupling(cm) 19

20 Ex Packing F = 1/min, 8 hours, (FM=0.75) H = 14 in, A=90 Significant control is not needed. 20

21 Redesign Suggestion HM.71, AM.71, FM.75 Assuming that large horizontal distance is due to the size of the object, then the horizontal distance could only be reduced by making the object smaller or reorienting the object. Eliminate body twist by providing a curved chute to bring the object in front of the worker.(am = 1) raising the height of conveyor A or reducing the height of bench B 21

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人因危害風險鑑別方法

人因危害風險鑑別方法 occupational ergonomics 2.1 subjective objective questionnaire Nordic Musculoskeletal QuestionnaireNMQ Nordic Council of Ministries NMQ NMQ reliability77 100 validity 80 100 [1]NMQ 2.2 checklist 2.2.1