Long-term Lower Extremity Prosthetic Costs in Children With Traumatic Lawnmower Amputations

Objectives  To evaluate prosthetic costs of pediatric lawnmower amputations; to see if reducing the incidence of pediatric lawnmower amputations could result in significant cost savings; and to consider if a cost analysis could be useful to implement more safety features (voluntarily or legislatively).

Design  Pediatric lawnmower amputees from 1980 to 2000 were reviewed to determine age at time of injury, level of amputation, number of prostheses, and lifetime per prosthesis. A standard prosthetic program beginning at amputation and ending at age 18 years was constructed. An aggregate cost was calculated according to the proportion of amputation levels. The cost burden for prosthetic care was estimated from the statistics of US pediatric lawnmower injuries.

Setting  Referral pediatric orthopedic center.

Patients  Fifty-three lower extremity amputees with 58 lower extremity amputations at a mean ± SD age of 4.7 ± 2.5 years were reviewed.

Results  The percentage of amputee children injured by riding lawnmowers was 80%; the percentage injured by riding lawnmowers engaged in reverse was 39%. Prosthetic costs from the time of injury to the age of 18 years range from $73 140 to $116 040 per single lower extremity amputation. With 600 to 650 new childhood amputations per year due to lawnmowers, the new annual burden for prosthetic costs thus ranges from $43.88 to $75.42 million, or (600)($73 140) to (650)($116 040).

Conclusions  Further encouragement of lawnmower manufacturers to install improved safety devices (such as those to disengage power while in reverse mode of operation), new research on improved safety measures, and continued promotion of educational campaigns regarding the dangers of children being around and/or operating riding lawnmowers and garden tractors should be pursued. This will result in significant cost savings as well as incalculable health savings.

Lawnmowers are a common cause of traumatic pediatric amputations and are the most common cause in 2 recent studies.^1,2 Lawnmower injuries also represent significant morbidity,^3-8 especially financial burden.^4,6,9 Children with lawnmower injuries and amputations are younger in age than lawnmower-injured children without amputations.⁶ Younger children have a longer time until skeletal maturity, and subsequently more prostheses are needed during their remaining years of growth. These multiple prostheses are a significant financial burden to the family, especially since many third-party payers only pay for 1 or 2 prosthetic devices over the entire lifetime of the patient and/or insurance policy.

Prevention is superior to treatment of these injuries, from both the medical and the financial perspectives. In 1982, the Consumer Product Safety Commission (CPSC) mandated installation of “deadman” switches on all newly manufactured walk-behind mowers, resulting in a 40% decrease in the incidence of injury.¹⁰ However, most pediatric lawnmower injuries, especially in younger children, are due to riding lawnmowers.^4,6-8 Improvement in safety features of riding lawnmowers has been slow, unlike that for walk-behind mowers. Reducing the incidence of riding lawnmower injuries would result in significant cost savings, not only for the acute care component but also for long-term prosthetic care. A cost analysis could provide useful information to implement more safety features, either voluntarily or legislatively. It is the purpose of this study to review and evaluate the prosthetic costs of these injuries during childhood, which can hopefully be used to improve prevention of these injuries by encouraging further passive protective mechanisms.

Shriners Hospital for Children/Twin Cities (Minneapolis, Minn) accepts any child for care regardless of ability to pay and provides a child with as many prostheses as needed until the age of 18 years. Because of this financial advantage, many families seek prosthetic care for their child at this institution immediately after limb loss. Also, this institution is located in the midwestern United States where there are a large number of lawnmowers. Because of these factors, the Limb Deficiency Service at Shriners Hospital for Children/Twin Cities is extremely active, affording a unique opportunity to study the prosthetic costs of pediatric lawnmower amputations.

After institutional review board approval, a retrospective review of all children with amputations cared for at Shriners Hospital for Children/Twin Cities between 1980 and 2000 was conducted. During this time span, there were a total of 235 children with 256 traumatic amputations. The medical records of these 235 children were reviewed; the amputation was due to a lawnmower in 69 of these 235 children. The age at time of injury and the level of amputation (eg, above-knee, below-elbow, etc) were recorded. The number and types of prostheses used were noted, as was the lifetime span of each prosthesis. From this data, a typical prosthetic program for each level of amputation was constructed, beginning at the average age of amputation for each level and ending at age 18 years. For example, a child with an amputation at level A occurring at an average age of x, with y number of prostheses per year, would need y(18−x) prostheses until the age of 18 years. A typical prosthetic prescription program was constructed by a certified prosthetist, taking into account different types of feet, hinges, sockets, etc, which change as the child ages.

For the purposes of cost analyses, only lower extremity amputations were used because the indication for upper extremity prosthetic prescription is controversial, with many children electing not to use upper extremity prostheses. Prosthetic costs (in 2003 US dollar equivalents) per child for each particular amputation level were calculated using the following methods (Table 1).

1. The prosthetic costs used were those allowed by standard third-party payers in Indiana, a midwestern state with a median cost of living. The 2000 consumer price index for Indiana was 101.02, with 100 being the median state consumer price index that year.¹¹ Thus, these costs are an average estimate for the entire United States.

2. Reasonable annual estimates (both low and high) for routine repairs were included, as dictated by 1 author’s (D.A.T.) clinical experience.

3. An aggregate cost (prosthetic costs plus repair costs) was calculated according to the proportion of amputation levels. The proportions used were those from this study and those from a previous study conducted by the Pediatric Orthopaedic Society of North America.⁶ The present study represents a population with more proximal amputations, while the previous study represents a population with more distal amputations. The aggregate costs were calculated using the amputation level proportions for each study, resulting in a cost range.

4. The cost burden for prosthetic care due to pediatric lawnmower amputations until the age of 18 years was then estimated from the annual statistics of pediatric lawnmower injuries in the United States, using values published in the literature as well as data from the National Electronic Injury Surveillance System (NEISS) (Table 2).¹²

Of the 69 children with amputations, 53 children had 58 amputations involving the lower extremities. Data from these 53 children make up the results of this study. The mean ± SD age at injury was 4.7 ± 2.5 years. The amputation was at the level of the foot in 26 children, the ankle in 13, below-knee in 18, and above-knee in 1. The type of lawnmower involved was recorded in the medical records of 36 children; it was a riding mower in 30 cases (83%) and a walk-behind mower in 6 (17%). Of the 30 children injured by a riding mower, the passenger/bystander status was noted for 20 children; 16 (80%) of the children were not riding on the mower, and 4 (20%) were riding on the mower. For 19 children, the position of the child relative to the mower was known; 9 children (47%) were injured when the mower was in reverse, 1 child (6%) was injured when the mower was moving forward, and 9 children (47%) were injured when they fell and slid under the rotary blade. Of 16 children who were not riding on the mower, the position of the child was known for 13; 7 children were backed over by the mower, and 6 children fell and slid under the mower. Overall, approximately 39% (47% [9 cases ] of 83% [30 cases]) of the children were injured by riding mowers in reverse mode.

An estimate of the annual number of amputations due to lawnmowers in children up to 18 years of age can be obtained using data from the NEISS¹² (Table 2). From 1993 to 2002, the total number of lawnmower injuries in the NEISS data was 15 499 for an estimated nationwide number of 677 971; the total number of lawnmower injuries in those aged 18 years or younger in the NEISS data was 2330 for an estimated nationwide number of 97 115. When accessing the NEISS data bank for those with amputations and those with amputations who were 18 years of age or younger, national estimates were not given because of small numbers (<1200) or a coefficient of variation greater than 0.33.¹² Therefore, we estimated the total number of amputations in children younger than 18 years of age by using proportions of the NEISS actual data. An estimate of the total number of children with amputations over the 10-year period from 1993 to 2002 is (677 971)(137)/(15 499) = 5992, or 599 amputations per year.

Alternatively, the annual number of lawnmower amputations can be estimated using values from the literature. Approximately 14% of lawnmower injuries occur in children younger than 18 years of age, or 9400 pediatric lawnmower injuries per year,¹³ with an amputation rate of 7%.¹³ This results in an estimated 658 new childhood amputations due to lawnmowers per year: (9400)(0.07) = 658. The 600 value from the NEISS data and the 658 value from the literature are very similar. For the purposes of this study, we used an upper limit of 650 and a lower limit of 600 amputations due to lawnmowers per year.

The overall aggregate cost values were calculated using the following methods.

1. The percentages of each amputation level are shown in Table 1. For each amputation level, the total prosthetic cost from injury to age 18 years is first calculated.

2. Total prosthetic cost = (18−age at time of injury) [(number of prostheses/y)(cost per prosthesis) + (annual cost for repairs)].

3. The weighted average for each new pediatric amputation is then calculated. For example, the aggregate total cost for any one new pediatric amputee using the present study amputation level proportion data and the upper repair estimate is (0.38)(79 574) + (0.19)(231 578) + (0.28)(144 642) + (0.01)(130 247) = 30 238 + 43 999 l+ 40 499 + 1302 = $116 040.

4. Assuming 650 new pediatric amputations due to lawnmowers per year, the present study amputation level proportions, and the upper repair estimate, the annual new cost for pediatric prosthetic care is (650)(116 040) = $75.426 000.

5. Assuming 600 new pediatric amputations due to lawnmowers per year, using the Pediatric Orthopaedic Society of North America study amputation level proportion data and the lower repair estimate, the annual new cost for pediatric prosthetic care is (600)(73 140) = $43.884 million. Thus, an annual financial burden to US society for pediatric prosthetic care due to lawnmower amputations ranges from $43.88 million to $75.42 million.

In this study, approximately 39% of the children were injured by a riding mower operated in reverse. Certain lawnmower manufacturers now equip riding lawnmowers with no mowing in reverse (NMIR) devices. In an attempt to determine the availability of NMIR devices, requests were sent to manufacturers of riding lawnmowers and lawn/garden tractors. The responses are shown in Table 3. Five of the 10 manufacturers are presently installing NMIR devices on all newly manufactured products. None have the ability to retrofit a previously manufactured lawnmower/garden tractor with an NMIR.

The estimates given in this study are likely low. First, the cost of acute care was excluded. Second, only lower extremity amputations were considered. Third, the costs in lost wages, travel for medical care, and psychological counseling for the families of these children were not included. Fourth, garden tractors were not included.

In this study, approximately 39% of the children were injured by riding mowers in reverse mode. Assuming that all riding mowers could be equipped with NMIR devices, the savings from prosthetic costs alone, assuming that all 39% could be prevented by an NMIR device, would range from $28.52 to $45.25 million: (0.39)($73.14 to $116.04 million). However, NMIR devices cannot be installed on the new zero-turn-radius mowers. The unique design of this mower allows each rear wheel to operate independently; one wheel can turn fully forward and another fully in reverse, allowing for 360° turns. This results in superior maneuverability and time savings while mowing.^14,15 Since one wheel needs to go in reverse and the other needs to go forward at the same time, NMIR devices and zero-turn-radius mowers are incompatible. These mowers, initially made for commercial use, are becoming increasingly popular for residential use. This increase in popularity is extremely concerning for the safety of children who might inadvertently come onto a yard where such a mower is being used. At this time, there are no data to show if the injury rate is higher with a zero-turn-radius model compared with a conventional riding mower.

The data from this study indicate the need to encourage lawnmower manufacturers to install NMIR devices on all units and to continue further research into newer safety measures. Society also needs to continue to promote educational campaigns regarding the dangers of children being around and/or operating riding lawnmowers and garden tractors. All physicians need to inform parents and patients of the American Academy of Pediatrics guidelines¹³ regarding lawnmower safety: (1) children should not be allowed to play in or be adjacent to areas where lawnmowers are being used; (2) children should not ride as passengers on mowers or be towed behind mowers in carts or trailers; and (3) children should not operate lawnmowers until they have displayed the necessary levels of judgment, strength, coordination, and maturity. Most children are not ready to operate a walk-behind power mower until 12 years of age or a riding mower until 16 years of age. It is the duty of all involved in the care of children to spread this message.

Lawnmowers are the most common cause of pediatric amputations due to trauma. Prevention would be far preferable both for the patient and for cost savings to society.

In this study, it was calculated that the total new annual prosthetic cost burden to the United States for pediatric lawnmower amputations is $44 to $75 million. It is estimated that at least $28 to $45 million per year in cost savings could result from the installation of NMIR devices on riding lawnmowers.

Correspondence: Randall T. Loder, MD, James Whitcomb Riley Hospital for Children, 702 Barnhill Dr, Room 4250, Indianapolis, IN 46202 (rloder@iupui.edu).

Accepted for Publication: July 13, 2004.

Acknowledgment: The assistance of Patricia Doyle, RN, in the collection of data is greatly appreciated.