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Lower extremity fractures in motor vehicle collisions: The role of driver gender and height
Accid. Anal. and Prev., Vol. 27, No. 4, pp. 601-606, 1995 Copyright 0 1995 Elsevier Science Ltd Printed in the USA. All rights reserved ooo1-4575/95 $9.50 + .oo
Pergamon 0001-4575(95)00002-X
BRIEF COMMUNICATIONS
AND RESEARCH
NOTES
LOWER EXTREMITY FRACTURES IN MOTOR VEHICLE COLLISIONS: THE ROLE OF DRIVER GENDER AND HEIGHT* PATRICIA
C. DISCHINGER,
National
TIMOTHY
J. KERNS,
Study Center for Trauma and EMS, University Baltimore, MD, U.S.A. (Accepted
15 November
and JOSEPH of Maryland
A.
KUFERA
at Baltimore,
1994)
Abstract-In
a previous study it was noted that there was a higher incidence of lower-extremity fractures among women drivers. Analyses were based on a linkage between trauma registry and police crash report data. The present study addresses the issue of whether the differences noted are attributed to driver gender or are merely a reflection of differences in driver height. An inverse association was noted between driver height and the incidence of lower-extremity fractures. Those shorter than average (5’7”) for this population had a 64% increase in lower-extremity fracture, which can be mainly attributed to ankle/tarsal injuries. Thus, the incidence of these injuries appears to be a function of driver height, with an increase among shorter drivers, most of whom are women. Keywords-Lower-extremity
injuries,
Gender, Height, Motor vehicle occupant
chinger, Cushing et al., 1993; Siegel, Mason-Gonzalez, Dischinger, Read et al. 1993). Much still needs to be learned, however, about the incidence and mechanism of these injuries, so that effective interventions may be identified (Dischinger et al. in press). In a previous study of the incidence of lowerextremity injuries in a trauma center population, it was noted that: (a) there was a significantly higher incidence of lower-extremity injury in frontal collisions, (b) seatbelt use was not effective in preventing lower-extremity fractures (with the exception of the femur), and (c)there was a higher incidence of lowerextremity fracture among women (Dischinger, Cushing, and Kerns 1992). Upon further analysis, it was found that the major differences were attributable to injuries of the ankle and foot (tarsal). The purpose of this study was to try to determine whether these differences were more likely to be attributable to gender or to height, since women as a group tend to be shorter than men as a group.
INTRODUCTION Lower-extremity injuries are a common and costly cause of permanent disability and impairment resulting from motor vehicle crashes (Huelke, O’Day, and States 1982; Reidelbach and Zeidler 1983; MacKenzie 1986; States 1986; Ward et al. 1991; Siegel and Dischinger 1992; Siegel, Mason-Gonzalez, Dischinger, Cushing et al. 1993; Siegel, Mason-Gonzalez, Dischinger, Read et al. 1993). Furthermore, it is anticipated that these injuries will become relatively more important in the future as more frequent use of seatbelts and availability of airbags lead to increased survival rates. In a 1988 study in Maryland, it was noted that, due to the high prevalence of lower-extremity injuries, they accounted for 40% of the one-year vehicular trauma treatment charges in the state (MacKenzie, Shapiro, and Siegel 1988). In an in-depth trauma center-based crash reconstruction study of vehicular trauma patients, intrusion of the toepan of the vehicle was associated with distal tibia fractures and fractures to the talus, ankle joint dislocations, and foot bone fractures (Siegel and Dischinger 1992; Siegel, Mason-Gonzalez, Dis-
METHODS Injury data were obtained for all vehicular trauma patients admitted to the R Adams Cowley Shock Trauma Center during the period between
*Presented at the Annual Conference of the Association for the Advancement of Automotive Medicine, September 21-23, 1994, Lyon, France. 601
Brief Communications
602
July 1987 and December 1992. For the purpose of these analyses, extremity injuries included those distal to the hip. Data from the trauma registry were linked with that from police crash reports to allow analyses of the relationship between injuries and crash characteristics. Subsequent analyses are based on 1520 nonejected car/truck drivers who were involved in either frontal or left lateral collisions. From the police report, data on direction of impact were determined from the diagram of the vehicle and the corresponding numbers shown in Fig. 1. Frontal impacts were defined as 1, 2, 3 on the police report diagram. Left lateral impacts, on the other hand, were defined as 4 or 7, from the diagram. Data on the heights and weights of the drivers were obtained from the trauma registry (Dunham et al. 1989). Comparisons of incidence rates were made by Pearson chi-square tests of independence. Odds ratios (Hosmer and Lemeshow 1989) were computed to determine the risk of lower extremity injuries among different subgroups. To determine those variables that are risk factors for lower-extremity fracture, stepwise logistic regression analyses were performed, with all independent variables initially included to adjust for error (Hosmer and Lemeshow 1989).
RESULTS Table 1 shows the incidence of lower extremity fracture by gender, for each of the specific fracture types. As mentioned previously, the overall incidence of lower-extremity fracture was significantly higher in women (20% versus 13%, p < .Ol). It is apparent from this table that the overall excess of
6
8 Fig. 1. Car schematic.
and Research Notes
Table 1. Incidence by gender for specific fracture types In-jury
Male (n = 959)
Female (n = 561)
Femur Patella Tib/Fib Ankle Tarsal
8.5% 3.1% 4.8% 4.2% 4.4%
8.0% 3.7% 6.8% 8.2% 8.0%
(81) (30) (46) (4Oj (42)
(45) (21) (38) (46j (45)
Total 8.3% 3.4% 5.5% 5.7% 5.7%
(126) (51) (84) i86j (87)
p-value ns .06 ns .OOl .02
lower-extremity fractures among women is attributable primarily to ankle/tarsal fractures. Since the average height for women was significantly less than that for men (5’S’ versus S’lO”), gender-specific rates were determined. The incidence rate for women 5’5” or less was 23% as compared to 16% for taller women. The incidence rate for men 5’10” or less was 15% as compared to 10% for taller men. Figures 2 and 3 show the incidence of each of the specific fractures, by gender, for those above and below the mean height of each gender population. These heights are in line with those reported for the U.S. population by the National Center for Health Statistics (5’9.1” for men and 5’3.7” for women) (National Center for Health Statistics, 1976-1980). Odds ratios that correspond to Figs. 2 and 3 are presented in Table 2 for men, women, and the total group. It is apparent that, even for men, those who are shorter have an increased risk, approximately twofold, of tarsal and ankle injury. For women, the difference in ankle injuries is of borderline statistical significance, due to fewer observations and a rather high proportion of injuries to those of height 5’6” and 5’7”; however, the trend of a higher incidence in shorter women drivers is still evident. Since these findings show that height is associated with the risk of lower extremity fracture, specifically ankle/tarsal fractures, in both men and women drivers, both groups have been combined and grouped by height in Fig. 4. Drivers have been divided into three categories of height: smaller than 5’5”, 5’6”-5’10”, and taller than 5’10”. As shown in Fig. 4, there is an inverse association between height and each of the types of lower extremity fracture. The declining proportion of lower extremity fractures with increasing driver height was found to be significant for patella, ankle, and tarsal fractures. In an effort to explore possible risk factors for injuries of the tarsal and ankle in this population of drivers, a multivariate regression analysis was performed. Age was not included in the model, as it was not associated with ankle/foot injury. Variables
Brief Communications
603
and Research Notes
.._.___..............................-.................._
. . . . . . . . . . . . . . . . . . . . . .._.______......____..........______
Patella
Femur
l
Wb_Fib
I%3<=SlV
Tanal
Ankle*
In > 5'lV
l
l
- p<.o6
Fig. 2. Incidence of specific fractures in males above and below the average height.
entered into the model as independent variables ineluded seatbelt use, type of collision (frontal versus lateral), driver weight, driver height, gender, and a height-by-gender interaction term. Factors significantly associated with the occur-
rence of ankle/tarsal injuries included type of collision (frontal), height of driver, and the height-bygender interaction. The significance of the interaction term indicates that the distribution of ankle/ tarsal injuries by height differs by gender. A close
10%
a96
Femur
-
Patella
Tlb_Flb
Ankle*
Tarsal * = pe.07
Fig. 3. Incidence of specific fractures in females above and below the average height.
604
Brief Communications
and Research Notes
Table 2. Odds ratios for specific fractures Male (n = 959) Fracture Femur Patella Tib/Fib Ankle Tarsal
p-value
Female (n = 561)
Odds ratio
NS .02 NS .OS .OS
p-value
Odds ratio
NS NS NS .07 NS
2.6 2.0 1.9
examination of the data indicates that the significance of the interaction term may be due to a difference in the distribution of men and women in the three height categories of Fig. 4. Only 5% (n = 47) of the men in the study are shorter than the average height for the women (5’S’), and only 3% (n = 14) of the women are taller than the average height for the men (5’10”). By removing the small groups of men shorter than 5’5” and women taller than 5’10” and focusing on the remaining drivers (912 men and 547 women), an increase in ankle/tarsal injury with decreasing height is observed for both men and women. The results for men are shown in Fig. 5. There is a striking difference in the incidence of ankle/ tarsal injuries, with an incidence rate of 2.0% for men 6’1”-6’2”, as compared with an incidence of 9.7% for men 5’7”-5”s”. Regression analyses for this group of men show that for each inch decrement in height, there is an approximate 10.4% increase in the risk of ankle/tarsal injury. A similar analysis is presented for women in Fig. 6. Once again there
Total (n = 1520) p-value
Odds ratio
NS NS NS .Ol .Ol
2.0 2.0
1.9
exists a difference in incidence with height, although the relative increase is not as great because women drivers started out with a higher incidence rate. Regression analyses for the women show an approximate 1.4% increase in the risk of injury for each inch decrement. An analysis of the incidence of ankle/tarsal injuries by inch of height for all drivers suggests a marked decline in these injuries for those taller than the average height of 5’7”. Thus, this indicates women as a group are at higher risk since 85% are smaller than 5’7”. Vehicle wheelbase and weight were available for approximately 60% of the study cases. When included in a model with the previously mentioned variables, however, these vehicle characteristics showed no significant association with ankle/tarsal injuries. CONCLUSIONS In a previous analysis of the incidence of lower extremity fractures in a trauma center population of
1096
896
6%
4%
2%
0%
Femur
Patella* tzi
<-5s. (n-m)
llb_Flb
•s~**l~
(n=esS)
H >S'lo= (n=474)
l
-
p<.os
Fig. 4. Specific fractures by height category (males and females combined).
Brief Communications and Research Notes
5T-5'0'
0
605
are required to explore the role of driver height and positioning of the seat and foot as related to the causation of these disabling injuries.
59'~5'10'
0
REFERENCES
tiT
9.7%
8.4%
6.4%
2.0%
Fig. 5. Ankle/tarsal injuries in men: incidence by height.
injured drivers, it was noted that women drivers had a significantly higher incidence of these injuries, and that the predominant difference was attributable to ankle/tarsal injuries. In addition, seatbelts were shown to be ineffective in preventing these fractures. Our results indicate an inverse association between driver height and the incidence of lower extremity fractures. Those shorter than average (5’7”) for this population had a 64% increase in lower extremity fracture, which can be mainly attributed to ankle/tarsal injuries. Thus, the incidence of these injuries appears to be a function of driver height, with an increase among shorter drivers, most of whom are women. These findings may be a reflection of leg position (the angle of the femur or tibia relative to the ankle) as a function of seat placement. Other factors might include drivers’ foot size or the contribution of knee contacts. The possible influence of foot placement and vehicular intrusion on occupant lower limb injury in frontal crashes has recently been described (Pilkey et al. in press). Further experimental studies
52w3'
5'4'6'5'
5W-59'
5W6T
0
0
B
17.1%
14.6%
13.9%
Fig. 6. Ankle/tarsal injuries in women:
incidence
11.9% by height.
Dischinger, P.; Cushing, B.; Kerns, T. Lower extremity fractures in motor vehicle collisions: Influence of direction of impact and seatbelt use. In: 36th Proceedings of the Association for the Advancement of Automotive Medicine; 1992: pp. 319-325. Dischinger, P. C.; Burgess, A. R.; Cushing, B. M.; O’Quinn, T. D.; Schmidhauser, C. B.; Ho, S. M.; JUliano, P. J.; Bents, F. D. Lower extremity trauma in vehicular front-seat occupants: Patients admitted to a Level I trauma center. In: In-depth accident investigation: Trauma team findings in late model vehicle collisions. Warrendale, PA: Society of Automotive Engineers, Inc.; 1994:11-l% Dunham, C. M.; Cowley, R. A.; Gens, D. R.; Ramzy, A. I.; Rodriguez, A.; Belzberg, H.; Wiles, C. E., III. Methodologic approach for a large functional trauma registry. Maryland State Medical Journal 38:227-233; 1989. Hosmer, D. W.; Lemeshow, S. Applied logistic regression. New York: Wiley; 1989. Huelke, D. F.; O’Day, J.; States, J. D. Lower extremity injuries in automobile crashes. Accident Analysis and Prevention 114:95-106; 1982. MacKenzie, E. J. The public health impact of lower extremity trauma. In: Biomechanics and Medical Aspects of Lower Limb Injuries. Warrendale, PA: Society of Automotive Engineers, Inc.; 1986: 161-170. MacKenzie, E. J.; Shapiro, S.; Siegel, J. H. The economic impact of vehicular trauma: One year treatment related expenditures. In: 32nd Proceedings of the Association for the Advancement of Automotive Medicine; 1988: pp. 53-68. National Center for Health Statistics. National health and nutrition examination 1976- 1980. Hyattsville, MD: US Department of Health and Human Services; May 1985. Pilkey, W. D.; Sieveka, E. M.; Crandall, J. R.; Klopp, G. The influence of foot placement and vehicular intrusion on occupant lower limb injury in full-frontal and frontal-offset crashes. Paper no. 94 S4 W 31 In: Proceedings of the 14th International Technical Conference on Enhanced Safety Vehicles, Munich, Germany, 1994; pp. 734-741 Reidelbach, W.; Zeidler, F. Comparison of injury severity assigned to lower extremity skeletal damages versus upper body lesions. In: 27th Proceedings of the American Association for Automotive Medicine; 1983: pp. 141-155. Siegel, J. H.; Dischinger, P. C. Medical consequences of car crashes: An automobile crash trauma study. DTNH 22-88-C-07007. Washington, DC: National Highway Traffic Safety Administration; 1992. Siegel, J. H.; Mason-Gonzalez, S.; Dischinger, P.; Cushing,,B.; et al. Safety belt restraints and compartment intrusions in frontal and lateral motor vehicle crashes: Mechanisms of injuries, complications, and acute care costs. Journal of Trauma 34:736-759; 1993.
606
Brief Communications
Siegel, J. H.; Mason-Gonzalez, S.; Dischinger, P. C.; Read, K. M.; et al. Causes and costs of injuries in multiple trauma patients requiring extrication from motor vehicle crashes. Journal of Trauma 35:920-931; 1993b. States, J. D. Adult occupant injuries of the lower limb. In: Biomechanics and Medical Aspects of Lower Limb
and Research Notes
Injuries. Warrendale, PA: Society of Automotive Engineers, Inc.; 1986: 97-107. Ward, E.; Pattimore, D.; Thomas, P.; Bradford, M. Leg injuries in car accidents-Are we doing enough? In: Proceedings of the International Conference on the Biomechanics of Impacts (IRCOBI), Berlin, Germany, 1991: 321-336.
Pergamon 0001-4575(95)00002-X
BRIEF COMMUNICATIONS
AND RESEARCH
NOTES
LOWER EXTREMITY FRACTURES IN MOTOR VEHICLE COLLISIONS: THE ROLE OF DRIVER GENDER AND HEIGHT* PATRICIA
C. DISCHINGER,
National
TIMOTHY
J. KERNS,
Study Center for Trauma and EMS, University Baltimore, MD, U.S.A. (Accepted
15 November
and JOSEPH of Maryland
A.
KUFERA
at Baltimore,
1994)
Abstract-In
a previous study it was noted that there was a higher incidence of lower-extremity fractures among women drivers. Analyses were based on a linkage between trauma registry and police crash report data. The present study addresses the issue of whether the differences noted are attributed to driver gender or are merely a reflection of differences in driver height. An inverse association was noted between driver height and the incidence of lower-extremity fractures. Those shorter than average (5’7”) for this population had a 64% increase in lower-extremity fracture, which can be mainly attributed to ankle/tarsal injuries. Thus, the incidence of these injuries appears to be a function of driver height, with an increase among shorter drivers, most of whom are women. Keywords-Lower-extremity
injuries,
Gender, Height, Motor vehicle occupant
chinger, Cushing et al., 1993; Siegel, Mason-Gonzalez, Dischinger, Read et al. 1993). Much still needs to be learned, however, about the incidence and mechanism of these injuries, so that effective interventions may be identified (Dischinger et al. in press). In a previous study of the incidence of lowerextremity injuries in a trauma center population, it was noted that: (a) there was a significantly higher incidence of lower-extremity injury in frontal collisions, (b) seatbelt use was not effective in preventing lower-extremity fractures (with the exception of the femur), and (c)there was a higher incidence of lowerextremity fracture among women (Dischinger, Cushing, and Kerns 1992). Upon further analysis, it was found that the major differences were attributable to injuries of the ankle and foot (tarsal). The purpose of this study was to try to determine whether these differences were more likely to be attributable to gender or to height, since women as a group tend to be shorter than men as a group.
INTRODUCTION Lower-extremity injuries are a common and costly cause of permanent disability and impairment resulting from motor vehicle crashes (Huelke, O’Day, and States 1982; Reidelbach and Zeidler 1983; MacKenzie 1986; States 1986; Ward et al. 1991; Siegel and Dischinger 1992; Siegel, Mason-Gonzalez, Dischinger, Cushing et al. 1993; Siegel, Mason-Gonzalez, Dischinger, Read et al. 1993). Furthermore, it is anticipated that these injuries will become relatively more important in the future as more frequent use of seatbelts and availability of airbags lead to increased survival rates. In a 1988 study in Maryland, it was noted that, due to the high prevalence of lower-extremity injuries, they accounted for 40% of the one-year vehicular trauma treatment charges in the state (MacKenzie, Shapiro, and Siegel 1988). In an in-depth trauma center-based crash reconstruction study of vehicular trauma patients, intrusion of the toepan of the vehicle was associated with distal tibia fractures and fractures to the talus, ankle joint dislocations, and foot bone fractures (Siegel and Dischinger 1992; Siegel, Mason-Gonzalez, Dis-
METHODS Injury data were obtained for all vehicular trauma patients admitted to the R Adams Cowley Shock Trauma Center during the period between
*Presented at the Annual Conference of the Association for the Advancement of Automotive Medicine, September 21-23, 1994, Lyon, France. 601
Brief Communications
602
July 1987 and December 1992. For the purpose of these analyses, extremity injuries included those distal to the hip. Data from the trauma registry were linked with that from police crash reports to allow analyses of the relationship between injuries and crash characteristics. Subsequent analyses are based on 1520 nonejected car/truck drivers who were involved in either frontal or left lateral collisions. From the police report, data on direction of impact were determined from the diagram of the vehicle and the corresponding numbers shown in Fig. 1. Frontal impacts were defined as 1, 2, 3 on the police report diagram. Left lateral impacts, on the other hand, were defined as 4 or 7, from the diagram. Data on the heights and weights of the drivers were obtained from the trauma registry (Dunham et al. 1989). Comparisons of incidence rates were made by Pearson chi-square tests of independence. Odds ratios (Hosmer and Lemeshow 1989) were computed to determine the risk of lower extremity injuries among different subgroups. To determine those variables that are risk factors for lower-extremity fracture, stepwise logistic regression analyses were performed, with all independent variables initially included to adjust for error (Hosmer and Lemeshow 1989).
RESULTS Table 1 shows the incidence of lower extremity fracture by gender, for each of the specific fracture types. As mentioned previously, the overall incidence of lower-extremity fracture was significantly higher in women (20% versus 13%, p < .Ol). It is apparent from this table that the overall excess of
6
8 Fig. 1. Car schematic.
and Research Notes
Table 1. Incidence by gender for specific fracture types In-jury
Male (n = 959)
Female (n = 561)
Femur Patella Tib/Fib Ankle Tarsal
8.5% 3.1% 4.8% 4.2% 4.4%
8.0% 3.7% 6.8% 8.2% 8.0%
(81) (30) (46) (4Oj (42)
(45) (21) (38) (46j (45)
Total 8.3% 3.4% 5.5% 5.7% 5.7%
(126) (51) (84) i86j (87)
p-value ns .06 ns .OOl .02
lower-extremity fractures among women is attributable primarily to ankle/tarsal fractures. Since the average height for women was significantly less than that for men (5’S’ versus S’lO”), gender-specific rates were determined. The incidence rate for women 5’5” or less was 23% as compared to 16% for taller women. The incidence rate for men 5’10” or less was 15% as compared to 10% for taller men. Figures 2 and 3 show the incidence of each of the specific fractures, by gender, for those above and below the mean height of each gender population. These heights are in line with those reported for the U.S. population by the National Center for Health Statistics (5’9.1” for men and 5’3.7” for women) (National Center for Health Statistics, 1976-1980). Odds ratios that correspond to Figs. 2 and 3 are presented in Table 2 for men, women, and the total group. It is apparent that, even for men, those who are shorter have an increased risk, approximately twofold, of tarsal and ankle injury. For women, the difference in ankle injuries is of borderline statistical significance, due to fewer observations and a rather high proportion of injuries to those of height 5’6” and 5’7”; however, the trend of a higher incidence in shorter women drivers is still evident. Since these findings show that height is associated with the risk of lower extremity fracture, specifically ankle/tarsal fractures, in both men and women drivers, both groups have been combined and grouped by height in Fig. 4. Drivers have been divided into three categories of height: smaller than 5’5”, 5’6”-5’10”, and taller than 5’10”. As shown in Fig. 4, there is an inverse association between height and each of the types of lower extremity fracture. The declining proportion of lower extremity fractures with increasing driver height was found to be significant for patella, ankle, and tarsal fractures. In an effort to explore possible risk factors for injuries of the tarsal and ankle in this population of drivers, a multivariate regression analysis was performed. Age was not included in the model, as it was not associated with ankle/foot injury. Variables
Brief Communications
603
and Research Notes
.._.___..............................-.................._
. . . . . . . . . . . . . . . . . . . . . .._.______......____..........______
Patella
Femur
l
Wb_Fib
I%3<=SlV
Tanal
Ankle*
In > 5'lV
l
l
- p<.o6
Fig. 2. Incidence of specific fractures in males above and below the average height.
entered into the model as independent variables ineluded seatbelt use, type of collision (frontal versus lateral), driver weight, driver height, gender, and a height-by-gender interaction term. Factors significantly associated with the occur-
rence of ankle/tarsal injuries included type of collision (frontal), height of driver, and the height-bygender interaction. The significance of the interaction term indicates that the distribution of ankle/ tarsal injuries by height differs by gender. A close
10%
a96
Femur
-
Patella
Tlb_Flb
Ankle*
Tarsal * = pe.07
Fig. 3. Incidence of specific fractures in females above and below the average height.
604
Brief Communications
and Research Notes
Table 2. Odds ratios for specific fractures Male (n = 959) Fracture Femur Patella Tib/Fib Ankle Tarsal
p-value
Female (n = 561)
Odds ratio
NS .02 NS .OS .OS
p-value
Odds ratio
NS NS NS .07 NS
2.6 2.0 1.9
examination of the data indicates that the significance of the interaction term may be due to a difference in the distribution of men and women in the three height categories of Fig. 4. Only 5% (n = 47) of the men in the study are shorter than the average height for the women (5’S’), and only 3% (n = 14) of the women are taller than the average height for the men (5’10”). By removing the small groups of men shorter than 5’5” and women taller than 5’10” and focusing on the remaining drivers (912 men and 547 women), an increase in ankle/tarsal injury with decreasing height is observed for both men and women. The results for men are shown in Fig. 5. There is a striking difference in the incidence of ankle/ tarsal injuries, with an incidence rate of 2.0% for men 6’1”-6’2”, as compared with an incidence of 9.7% for men 5’7”-5”s”. Regression analyses for this group of men show that for each inch decrement in height, there is an approximate 10.4% increase in the risk of ankle/tarsal injury. A similar analysis is presented for women in Fig. 6. Once again there
Total (n = 1520) p-value
Odds ratio
NS NS NS .Ol .Ol
2.0 2.0
1.9
exists a difference in incidence with height, although the relative increase is not as great because women drivers started out with a higher incidence rate. Regression analyses for the women show an approximate 1.4% increase in the risk of injury for each inch decrement. An analysis of the incidence of ankle/tarsal injuries by inch of height for all drivers suggests a marked decline in these injuries for those taller than the average height of 5’7”. Thus, this indicates women as a group are at higher risk since 85% are smaller than 5’7”. Vehicle wheelbase and weight were available for approximately 60% of the study cases. When included in a model with the previously mentioned variables, however, these vehicle characteristics showed no significant association with ankle/tarsal injuries. CONCLUSIONS In a previous analysis of the incidence of lower extremity fractures in a trauma center population of
1096
896
6%
4%
2%
0%
Femur
Patella* tzi
<-5s. (n-m)
llb_Flb
•s~**l~
(n=esS)
H >S'lo= (n=474)
l
-
p<.os
Fig. 4. Specific fractures by height category (males and females combined).
Brief Communications and Research Notes
5T-5'0'
0
605
are required to explore the role of driver height and positioning of the seat and foot as related to the causation of these disabling injuries.
59'~5'10'
0
REFERENCES
tiT
9.7%
8.4%
6.4%
2.0%
Fig. 5. Ankle/tarsal injuries in men: incidence by height.
injured drivers, it was noted that women drivers had a significantly higher incidence of these injuries, and that the predominant difference was attributable to ankle/tarsal injuries. In addition, seatbelts were shown to be ineffective in preventing these fractures. Our results indicate an inverse association between driver height and the incidence of lower extremity fractures. Those shorter than average (5’7”) for this population had a 64% increase in lower extremity fracture, which can be mainly attributed to ankle/tarsal injuries. Thus, the incidence of these injuries appears to be a function of driver height, with an increase among shorter drivers, most of whom are women. These findings may be a reflection of leg position (the angle of the femur or tibia relative to the ankle) as a function of seat placement. Other factors might include drivers’ foot size or the contribution of knee contacts. The possible influence of foot placement and vehicular intrusion on occupant lower limb injury in frontal crashes has recently been described (Pilkey et al. in press). Further experimental studies
52w3'
5'4'6'5'
5W-59'
5W6T
0
0
B
17.1%
14.6%
13.9%
Fig. 6. Ankle/tarsal injuries in women:
incidence
11.9% by height.
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Brief Communications
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and Research Notes
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