Power Lawnmower Injuries : Clinical Orthopaedics And Related Research®™

The rotary-type power lawnmower was commercial mower repair zephyrhills introduced during World War II because its manufacture required less steel than the traditional reel-type mower. 32 Although other varieties of mowers, especially riding and tractor style, have been developed for large areas, the walk-behind power mower has become the standard, and most frequently sold model of the industry. 26 In the year 2000, more than 6,000,000 walk-behind mowers and 1,700,000 riding mowers were shipped from manufacturers to retailers. Power mowers can cause significant injuries to users of the devices and to bystanders, who frequently are children. This peril was reported in numerous medical journals in the 1950s and 1970s. 12,13,19,32 In 1976, Ross et al 24 stated “Rotary power mowers are probably the most dangerous of common household tools.” Early after the United States Consumer Product Safety Commission was created in 1973, this watchdog group’s engineers, economists, and epidemiologic personnel targeted power mowers as a high-risk convenience. The United States Consumer Product Safety Commission was instrumental in developing a federal safety standard for all power mowers. This 1982 standard required all walk-behind mowers manufactured after that date to meet three requirements designed to reduce the chance of hand and foot contact with the blade. The brake must stop the blade’s rotation 3 seconds after the operator releases the handle mounted control bar. A foot shield was placed at the rear of the mower, and a label was required to warn the user to keep hands and feet away from the discharge chute. A similar safety standard was instituted in 1987 for riding mowers and garden tractors. These requirements included an “operator presence” control that stopped the blade when the operator left his or her position, a lower center of gravity to prevent tilting, and a higher seatback to support the mower operator. The gains in decreased mower-related injuries of the 1980s did not hold through the 1990s. Robert Depper, Division of Engineering, United States Consumer Products Safety Commission, confirmed that there have been no new federal standards for mowers (verbal communication, R Depper, 2001). Yet, several manufacturers have included an additional safety option in their ride-on power mower models. This improvement involves the placement of a “No Mow” control when the mower is placed in reverse drive. The intent is to reduce risk of backing over a bystander with the blade turning. However, most of the current models have a manual override of this safety measure, rendering the improvement ineffective. Figure 1 shows the National Electronic Injury Surveillance System data estimates for injuries associated with power mowers for 1997 to 2000. Total estimated injuries for 1997 were 60,016 injuries; for 1998, 75,375 injuries; for 1999, 69,480 injuries; and for 2000, 79,892 injuries. Riding mower use was associated with 19% of these injuries in 1997 and 1998; 14% in 1999; and 20% in 2000. 23Figure 2 shows the numbers of injuries associated with various age groups for these years. The majority of these injuries are in the greater than 25-year age group with the peak numbers in the 25- to 64-year group. Figure 3 shows similar information for injuries associated with riding power mowers. Again the majority of injuries are in individuals in the 25- to 64-year age range. However, the injuries in the 5- to 14-year group outnumber the injuries in the 15- to 24-year group for each of the years charted. The care costs of power mower-associated injuries are estimated at $475 million 23 annually in the United States. Loder and associates 16 estimated the cost of the initial hospital admission and treatment to be $90 million for the children’s injuries alone. “A typical 26-inch rotary mower blade rotating at 3,000 revolutions per minute develops a kinetic energy of 2,100 ft lb.”19 This force can do significant damage to anything that comes into its path. Direct injuries to the upper and lower extremities are the most common result of improper use of the mower. For a riding mower, the force is even greater because energy produced relates to the square of the length of the blade. Indirect or missile injuries also can develop when the blade hits another object, such as a rock or tree branch, or sends a broken blade segment flying. A blade moving at 3000 revolutions per minute can launch a 1.5-lb object at 232 miles per hour. Unfortunately not all injuries associated with power mowers occur when the power is on. Burns have been reported either from direct contact with the hot mower engine, or from accidental ignition of spilled gasoline on the running motor or spark plug. Because of the seemingly preventable nature of mower accidents in children, several studies report on children’s injuries. 5,10,12,16,17 The most common injuries in all age groups are lacerations of skin, muscle, tendon, and joint; fractures, closed and open; amputations; direct and indirect injuries to the head and eye 2; burns 29; and other penetrating injuries. There is one report of a penetrating injury to the vena cava in a child. 18 Death can result from these injuries, most commonly in children hit or run over by a riding mower;1,8 however, deformity and disability are usually inevitable. Serious medical complications can develop from significant mower injuries. 3,16 The most common of these complications include infections (including bone), 11 soft tissue defects, and chronic ulcers. 7 Subsequent amputations secondary to neural and vascular compromise are not uncommon. Dormans et al 9 reported that 14 of 18 limbs with a shredding-type injury eventually required amputation. Psychologic sequelae of mower injuries are not insignificant especially in children. 11,25,30 Multidisciplinary management teams are recommended for the care of patients with serious injuries associated with power mower use. These teams include surgeons (general, orthopaedic, and plastic), rehabilitationists, therapists, psychologists, and social workers. Most of the injuries incurred in association with power mower use are preventable. This especially is true in the pediatric age range. A multicenter study collected by the Research Committee of the Pediatric Orthopaedic Society of North America showed that 85% of injuries in 144 children would have been prevented if children younger than 14 years were not allowed around mowers. Children’s injuries, especially as related to riding mowers, are the most distressing to the public and carry the greatest risk of morbidity and mortality. However, patients younger than 15 years who are treated in emergency rooms sustained, according to United States Consumer Product Safety Commission estimates, only 12% of the power mower related injuries from 1997 to 1999. Clearly power mower injury prevention programs must be directed to all age groups. These programs have taken two forms. The first is the United States Consumer Product Safety Commission’s suggestion of safety standards that become rules for the manufacturing industry. The changes in the design of the mowers and their controls have been partially effective in decreasing numbers of injuries. The placement of instruction labels on the appliances probably has been less successful because of consumer compliance and weakening credibility of manufacturers’ labels. Consumer awareness programs are the second thrust of the injury prevention campaign. All major mower manufacturers distribute safety manuals with new product sales. The information from these manuals is fairly standard and uses wording from the United States Consumer Product Safety Commission safety standards. These safety instructions also are available to the public on the manufacturers’ websites and the website of the Outdoor Power Equipment Institute. According to the Pennsylvania Trauma Systems Foundation, orthopaedic surgeons were the admitting physicians for 47% of the children who had injuries associated with power mower injuries in the years 1989 to 1993. 4 Trauma surgeons admitted another 19%, most of whom certainly had musculoskeletal injuries. Orthopaedic surgeons have a major stake in the prevention and outcome of power mower injuries. A more aggressive program dedicated to the prevention of these injuries is the first step. Such a program would be aimed at continued public education on the issues surrounding power mower safety.