The role of cumulative physical work load in symptomatic knee osteoarthritis – a case-control study in Germany

Table 2 Occupational exposure to kneeling/squatting and lifting/carrying of loads and symptomatic knee osteoarthritis

Variable	Cases		Controls
	N	%	N	%	Adj. OR^a	95% CI	Adj. OR^b	95% CI
Kneeling and squatting combined
No kneeling/squatting	145	49.2	208	63.6	1.0	-	1.0	-
>0 – <870 h	15	5.1	39	11.9	0.7	0.3–1.5	0.5	0.2–1.2
870 – <4,757 h	32	10.8	40	12.2	1.4	0.8–2.5	0.8	0.4–1.5
4,757 – <10,800 h	40	13.6	22	6.7	2.8	1.5–5.4	1.6	0.8–3.4
> = 10.800 h	62	21.0	17	5.2	4.0	2.1–7.6	2.4	1.1–5.0
Cumulated lifting and carrying combined (kg*hrs.)
No lifting/carrying	75	25.4	153	46.8	1.0	-	1.0	-
>0 – <630 kg*hrs.	28	9.5	58	17.7	1.3	0.7–2.4	1.2	0.6–2.3
630 – <5,120 kg*hrs.	61	20.7	58	17.7	2.0	1.2–3.4	2.0	1.1–3.6
5,120 – <37,000 kg*hrs.	92	31.2	40	12.2	3.6	2.1–6.0	2.0	1.1–3.9
> = 37,000 kg*hrs.	35	11.9	17	5.2	3.5	1.7–7.2	2.6	1.1–6.1
Kneeling/squatting and lifting/carrying combined^c
Both no kneeling/squatting and no lifting/carrying	65	22.0	137	41.9	1.0	-	1.0	-
Kneeling/squatting >0 – <870 hrs. or lifting/carrying >0 – <630 kg*hrs.	26	8.8	58	17.7	1.2	0.7–2.3	1.1	0.5–2.1
Kneeling/squatting 870 – <4,757 hrs. or lifting/carrying >0 – <5,120 kg*hrs.	42	14.2	59	18.0	1.3	0.8–2.4	1.2	0.7–2.2
Kneeling/squatting 4,757 – <10,800 hrs. or lifting/carrying 5,120 – <37,000 kg*hrs.	78	26.4	42	12.8	3.5	2.0–6.0	2.7	1.5–4.8
Either kneeling/squatting >10,800 hrs. or lifting/carrying >37,000 kg*hrs.^d	69	23.4	26	8.0	3.8	2.1–6.8	3.4	1.8–6.3
Both kneeling/squatting >10,800 hrs. and lifting/carrying >37,000 kg*hrs.	14	4.7	4	1.2	7.8	2.1–28.3	7.9	2.0–31.5

^aAdjusted for age and region
^bAdjusted for age, region, body mass index, jogging/athletics, kneeling/squatting, and lifting/carrying (without considered variable)
^cThe respective highest exposure (concerning kneeling/squatting and lifting/carrying) is crucial for exposure classification
^dIf both conditions are fulfilled, the subject is assigned to the highest exposure category

ISSN: 1745-6673