Risk factors for plantar fasciitis among assembly plant workers

OBJECTIVE: The objective of this study was to determine the relative contributions of work activity (time spent standing, walking, or sitting), floor surface characteristics, weight, body mass index, age, foot biomechanics, and other demographic and medical history factors to the prevalence of plantar fasciitis.

DESIGN: A cross-sectional observational study design was used.

SETTING: The study site was an automobile engine assembly plant.

PARTICIPANTS: Full-time employees of the assembly plant who had been working at least 6 months.

ASSESSMENT OF RISK FACTORS: The independent variables included baseline demographics, medical history, ergonomic exposures, psychosocial factors, discomfort ratings, shoe characteristics, and foot biomechanics.

MAIN OUTCOME MEASUREMENTS: The dependent variable was the finding of plantar fasciitis on physical examination.

RESULTS: The study demonstrated that forefoot pronation on physical examination, high metatarsal pressure on the gait assessment, increasing time spent standing on hard surfaces, increased time spent walking, medium tenure at the plant, and an increased number of times getting in and out of the vehicle (for the truck/forklift drivers) increased the risk of presenting with plantar fasciitis. Rotation of shoes during the work week was found to reduce the risk of presenting with plantar fasciitis. Increased supervisor support showed a trend toward reducing the prevalence of plantar fasciitis.

CONCLUSIONS: Plantar fasciitis is relatively common in the manufacturing setting. These findings suggest several options for primary and secondary prevention strategies. Shoe rotation may be an effective strategy that may be used as either a primary or secondary strategy. The use of shoe orthoses with a medial longitudinal arch and metatarsal pad may be used as a preventive or treatment strategy. Work stations that decrease the percentage of time walking or standing on hard surfaces (eg, allowing workers to alternate between sitting and standing postures or providing cushioning mats for concrete surfaces) may lower the risk for plantar fasciitis.