Individual and occupational risk factors for knee osteoarthritis: results of a case-control study in Germany

Abstract

IntroductionA number of occupational risk factors are discussed in relation to the development and progress of knee joint diseases (for example, working in a kneeling or squatting posture, lifting and carrying heavy weights). Besides the occupational factors, a number of individual risk factors are important. The distinction between work-related and other factors is crucial in assessing the risk and in deriving preventive measures in occupational health.MethodsIn a case-control study, patients with and without symptomatic knee osteoarthritis (OA) were questioned by means of a standardised questionnaire complemented by a semi-standardised interview. Controls were matched and assigned to the cases by gender and age. Conditional logistic regression was used in analysing data.ResultsIn total, 739 cases and 571 controls were included in the study. In women and men, several individual and occupational predictors for knee OA could be described: obesity (odds ratio (OR) up to 17.65 in women and up to 12.56 in men); kneeling/squatting (women, OR 2.52 (>8,934 hours/life); men, 2.16 (574 to 12,244 hours/life), 2.47 (>12,244 hours/life)); genetic predisposition (women, OR 2.17; men, OR 2.37); and sports with a risk of unapparent trauma (women, OR 2.47 (≥1,440 hours/life); men, 2.58 (≥3,232 hours/life)). In women, malalignment of the knee (OR 11.54), pain in the knee already in childhood (OR 2.08), and the daily lifting and carrying of loads (≥1,088 tons/life, OR 2.13) were related to an increased OR; sitting and smoking led to a reduced OR.ConclusionsThe results support a dose-response relationship between kneeling/squatting and symptomatic knee OA in men and, for the first time, in women. The results concerning general and occupational predictors for knee OA reflect the findings from the literature quite well. Yet occupational risks such as jumping or climbing stairs/ladders, as discussed in the literature, did not correlate with symptomatic knee OA in the present study. With regards to occupational health, prevention measures should focus on the reduction of kneeling activities and the lifting and carrying of loads as well as general risk factors, most notably the reduction of obesity. More intervention studies of the effectiveness of tools and working methods for reducing knee straining activities are needed.

Occupational Physical Loading Tasks and Knee Osteoarthritis: A Review of the Evidence

“…6,7 More recently, some authors have recognized that homemakers should be considered when exploring occupational physical loading, since kneeling and lifting are central components of performing household chores. 13,14 This conclusion accords with a broader definition of occupation, such as that suggested by the Canadian Occupational Therapy Association: occupation is what people do to occupy themselves with some regularity or consistency by contributing to the productivity of their communities through engagement in the workforce or at home. 15 As several studies have been published since the last review, it is appropriate to update the literature on occupational exposure as a risk factor for knee OA.…”

“…Since the most recent published review, 6 14 new studies have been published that meet eligibility criteria for our review. 11,14,31,[33][34][35][36][37][38][39][40][41][42][43] The quality of the studies varied greatly (see Appendix 4); 16 studies scored b11 points, indicating high methodological quality, and 10 of these (58.8%) were published after 2004, the cut-off point for studies included in Jensen's review. 6 The majority of studies controlled for risk factors such as age and body mass index (BMI) that have been strongly implicated in knee OA in previous literature.…”

“…The study design included three cohort studies, 9,21,22 12 case-control publications from 11 studies, 11,13,14,20,[24][25][26][29][30][31][32]36 and three cross-sectional studies. 19,38,41 Of these, 11 articles 11,13,14,19,21,26,[29][30][31]36,38 showed a significantly positive association between heavy lifting and knee OA, with odds ratios (ORs) between 1.4 and 7.3.…”

“…The study design included three cohort studies, 9,21,22 12 case-control publications from 11 studies, 11,13,14,20,[24][25][26][29][30][31][32]36 and three cross-sectional studies. 19,38,41 Of these, 11 articles 11,13,14,19,21,26,[29][30][31]36,38 showed a significantly positive association between heavy lifting and knee OA, with odds ratios (ORs) between 1.4 and 7.3. Ten studies 9,13,14,19,25,26,29,31,41 were deemed to be of high quality based on the Jensen criteria; four of these were published since the 2004 review, 14,31,41,46 and three reported a statistically significant positive result.…”

Conceptual heuristic models of the interrelationships between obesity and the occupational environment

“…The impact of heavy workload, obesity, and traumatic knee injuries on the development of osteoarthritis have been reported from a prospective study of a Finnish cohort with ≥20 years of follow-up (71). The combined impact of kneeling/ squatting activities and obesity may also be important for the progression of existing knee osteoarthritis symptoms (72)(73)(74). Cross-sectional and longitudinal studies of obesity and occupational risk factors for osteoarthritis in working populations support the importance of a conceptual model of obesity, occupational kneeling/ squatting, and osteoarthritis.…”