Traumatogenic factors affecting the knees of carpet installers.
Bhattacharya-A; Mueller-M; Putz-Anderson-V
Appl Ergon 1985 Dec; 16(4):243-250
Biomechanical forces exerted on the knee and the use of a tool called the knee kicker were studied in carpet installers (SIC-1752). An ergonomic analysis of carpet installation tasks was performed for carpet layers at an actual job site or in a training school. Body postures were studied through films. Use of a power carpet stretcher and the knee kicker carpet stretcher, requiring force from a blow from the knee, was evaluated through task analysis and the use of films. A load cells was placed on the knee kicker to obtain measures of impact force. An accelerometer attached to the knee indicated leg acceleration. On the average carpet installers spent about 80 percent of their time kneeling using the knee kicker. Each worker studied averaged 141 kicks per hour delivered with the knee. Body postures during use of the knee kicker were frequently awkward. With the hardest knee kicks, impact force was about 3,019 Newtons. In delivery of kicks, accelerometer values sometimes exceeded 120 meters per second. At impact the flexion of knees averaged about 58 degrees. The authors conclude that installing carpet is demanding and produces a high risk of knee injury. The repetitive impact on the knee joint from the use of the knee kicker and repeated flexion may cause the high incidence of occupational knee morbidity among carpet layers.
NIOSH-Author; Medical-research; Occupational-hazards; Industrial-exposures; Physiological-measurements; Equipment-design; Physical-capacity; Health-hazards; Materials-testing; Risk-analysis; Ergonomics