Foot fractures and associated injuries in motorvehicle crashes: do restraints offer protection?

Foot and Ankle Surgery 1997

3: 199–203

Foot fractures and associated injuries in motorvehicle crashes: do restraints offer protection? J. A. LAGARES-GARCIA, S. KUREK, R. N. ANKNEY, S. L. MILLER AND K. M. HUGHES Department of Surgery and the Division of Trauma, Temple University/Conemaugh’s Memorial Medical Center, Johnstown, PA, USA

Summary The use of restraints reduces injury mortality in motor-vehicle crashes. However, 2 million Americans per year suffer disabling injuries in crashes, costing $167 billion. A retrospective review of 2271 patients involved in motor-vehicle crashes over 5 years was performed. Patients were evaluated for age, sex, injury severity, hospital stay, foot fractures, and other injuries. Eight-four patients sustained foot fractures in crashes. Restrained occupants had lower incidences of head injury, facial fractures, and pelvic injuries. Restraint use, however, did not lower the incidence of foot fractures. In conclusion, restraints do not lower the overall incidence of many non-fatal injuries. Foot fractures and associated injuries are significant causes of disability. Keywords: foot fractures, restraint use, associated injuries

Introduction Although the rate of motor-vehicle deaths per 10 000 registered vehicles dropped 94% between 1912 and 1993, 42 000 Americans died in motor-vehicle crashes in the USA in 1993 [1]. Motor-vehicle crashes remain a major cause of health care expenditure and loss of productivity in American society. The National Safety Council estimates that motor-vehicle crashes caused 2 million disabling injuries in 1993, with a cost of $167 billion [1]. Active and passive restraints reduce the number of injuries to major areas of the body. In particular, these devices protect the head and neck region and torso [2–6]. However, disabling injuries not involving

Presented December 4, 1995, at The Conference on Pelvic and Lower Extremity Injuries in Washington, DC, USA. Correspondence: K. Michael Hughes, DO, Division of Trauma, Temple University/Conemaugh’s Memorial Medical Center, 1086 Franklin Street, Johnstown, PA 15905, USA.  1997 Blackwell Science Ltd

the vital organs, such as foot fractures, may not be reduced by available restraint systems. Lower-limb injuries in motor-vehicle crashes remain a frequent cause of permanent disability and impairment [7]. The incidence of foot fractures and their relationship to associated injuries in motor-vehicle crashes was evaluated. The efficacy of restraint systems in reducing injuries was examined. The authors hypothesized that restraint systems would prevent some injuries but that no difference in the incidence of foot fractures between the restrained and unrestrained populations would exist. Injuries to their lower extremities were reviewed for their relevance to morbidity and, more specifically, to length of hospital stay.

Materials and methods A retrospective review of the medical records and trauma registry data of the 2271 patients involved

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Table 1 Foot fractures Site Talus Calcaneus Navicular Cuboid Cuneiform Metatarsal Phalanx Total

Table 2 Single fracture distribution Number (%) 37 28 2 11 11 81 2 172

Site

(22) (16) (1) (6) (6) (47) (1) (99)

in motor-vehicle crashes over a 5-year period was performed. Patients were admitted to a regional trauma centre servicing a 10 0002 mile, largely rural region. Patients were excluded from analysis if they were injured in motorcycle or all-terrain-vehicle crashes as these methods of transportation do not have standardized restraint systems, and mechanisms of injury differ from those of automobiles and light trucks. A foot fracture was defined as a fracture or dislocation involving the talus, calcaneus, navicular, cuboid, medial cuneiform, intermediate cuneiform, lateral cuneiform, metatarsal bones, or phalanx (Table 1). Isolated soft tissue and neurovascular injuries were not included. A restrained passenger was defined as a passenger protected by a seatbelt or a seatbelt and an airbag. Patients protected by airbag only were considered unrestrained. Statistical analyses were performed for continuous and noncontinuous variables with Fisher exact test, v2 and Student’s t-test. A P-value of less than 0.05 was considered significant.

Results Over a 5-year period 2271 patients were injured in motor-vehicle crashes. Of these, 2187 patients were admitted after motor-vehicle crashes without foot fractures, and 84 patients were admitted with foot fractures. There was no statistical difference in the ages of patients in the foot-fracture and non-foot-fracture groups (37 versus 34 years, respectively). However, 42 of the 884 females (5%) injured in motor-vehicle crashes sustained foot fractures, compared with 42 of the 1387 males (3%). This difference in incidence

Number (%)

Talus Calcaneus Navicular Cuboid Cuneiform Metatarsal Phalanx Tarsometatarsal dislocation Total

17 13 1 0 2 5 0

(43) (33) (2) (0) (5) (12) (0)

2 (5) 40

Table 3 Ankle and Foot Injury Scale (AFIS-S) distribution of the foot fractures Grade AFIS-S AFIS-S AFIS-S AFIS-S AFIS-S AFIS-S AFIS-S Total

Severity 0 1 2 3 4 5 6

No injury Minimal injury Mild injury Moderate injury Severe injury Very severe injury Currently untreatable

Number (%) 0 1 13 39 11 19 1 84

(0) (1) (16) (46) (13) (23) (1) (100)

of foot fractures between males and females was statistically significant (P<0.05). A total of 172 different fractures were encountered in the 84 patients in the foot-fracture group. There were a total of 40 single bone fractures, the talus being the bone most commonly affected (42%) (Table 2). One hundred and thirty-two fractures altogether were encountered in 47 patients. Six fractures (3%) were open – four calcaneal fractures, one medial cuneiform and one talar fracture. Seventy-five patients (89%) required operative management. Nine patients out of the 84 (11%) were managed nonoperatively. Severity of the foot fracture was assessed by the Ankle and Foot Injury Severity Scale (AFIS-S) [8]. Each patient was scored according to the AFIS-S guidelines. Patients with multiple foot fractures were scored according to the highest severity injury. Fortysix per cent of the patients sustained AFIS-S Grade 3 injury (moderate), followed by 23% of the patients with AFIS-S Grade 5 injury (very severe). One patient suffered an AFIS-S Grade 6 injury (currently untreateable) requiring amputation (Table 3).  1997 Blackwell Science Ltd, Foot and Ankle Surgery, 3, 199–203

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Table 4 Injuries and restraint use

Injury Blunt-abdominal trauma Blunt-thoracic trauma Pelvic fractures Upper-extremity fractures Facial fractures Closed-head injuries Foot fractures

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Restrained (%)∗

Unrestrained (%)†

Significance

211 (24%) 320 (36%) 92 (10%)

266 (19%) 436 (32%) 226 (16%)

P<0.05 NS P<0.05

193 (22%) 36 (4%) 519 (58%) 37 (4%)

256 94 1257 47

(19%) (7%) (92%) (3%)

NS P<0.05 P<0.05 NS

NS=not statistically significant. ∗n=897; †n=1374.

The length of hospital stay was significantly higher in the foot-fracture group at 13 days; compared with the non-foot-fracture group at 6 days (P<0.05). Three hundred and forty-two patients sustained injuries to the lower extremities (to the femur, tibia, fibula and tibiotalar). The average length of hospital stay for this group was 12.8 days, which was a significant increase when compared to the non-foot fracture group (6 days) (P<0.05), but similar to the average length of stay for patients with isolated foot fractures (13.0 days). Injury severity score tended to be higher in the foot-fracture population (17.9) in contrast to the nonfoot-fracture population (12.1). Alcohol intoxication (ETOH [0.10 mg/dl) was found to be higher in the non-foot-fracture group (42%) than the foot-fracture group (31%). Further analysis was performed to determine the relationship between foot fractures and associated injuries, including blunt-thoracic trauma, bluntabdominal trauma, pelvic injuries, upper-extremity injuries, facial fractures, and closed-head injuries (Table 4). The incidence of pelvic fractures was significantly higher in the foot-fracture group than the non-footfracture group. Nineteen of the 84 foot-fracture patients (23%) suffered pelvic injuries, compared with 299 of the 2187 (14%) non-foot-fracture patients. This difference was statistically significant (P<0.05). The incidence of facial fractures was also higher in the foot-fracture group than the non-foot-fracture group. Twenty-one of the 84 (25%) foot-fracture patients sustained facial fractures, while 109 of the non-foot-fracture patients (5%) had facial fractures (P<0.05). The incidence of closed-head injuries was significantly higher in the non-foot-fracture  1997 Blackwell Science Ltd, Foot and Ankle Surgery, 3, 199–203

population than the foot-fracture population. Of the non-foot-fracture patients, 1720 (79%) sustained a closed-head injury, compared with 56 of the 84 (67%) foot-fracture patients. This difference was statistically significant (P<0.05). There was no statistical difference between the incidence of blunt-thoracic trauma, blunt-abdominal trauma, and upperextremity injuries between the foot-fracture and nonfoot-fracture groups. The efficacy of restraint systems in reducing injuries was also examined. Thirty-seven of the 84 foot-fracture patients (44%) were restrained by either a seatbelt or a seatbelt and airbag. Eight hundred and sixty of the 2187 nonfoot-fracture patients (39%) were restrained by either a seatbelt or a seatbelt and airbag. The incidences of pelvic fractures, facial fractures, and closed-head injuries were lower among restrained drivers (P<0.05). Blunt-abdominal trauma, in contrast, occurred more frequently among restrained occupants than unrestrained occupants (P<0.05). Restraint use had no effect on the incidence of some injuries, such as blunt-thoracic trauma and upper-extremity injuries (Table 4). The incidence of foot fractures was not lowered by restraint use as well. Forty-seven of 1374 unrestrained patients (3%) suffered foot fractures, compared with 37 of 897 restrained patients (4%). Patients were identified according to the placement in the vehicle. The 2271 patients were made up of a total of 1476 drivers (65%) and 658 front seat passengers (29%). One hundred and thirty-seven patients were back seat passengers or of unknown placement. Of the 84 patients who sustained foot fractures, 69 (82%) were drivers and 15 (18%) were front seat passengers. There were no back seat passengers or persons of unknown status in this group. Drivers had a significantly higher proportion

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Table 5 Vehicular placement

Driver Front seat passenger Back seat/unknown Total

Non-foot fracture group

Foot fracture group

1476 (65%) 658 (29%) 137 (6%) 2271 (100%)

69 (82.1%) 15 (17.9%) 0 84 (100%)

of foot fractures than front seat passengers (P<0.05) (Table 5).

Discussion Restraint systems reduce the mortality from motorvehicle crashes. Airbags and seatbelts offer additional protection over seatbelts alone [6]. Airbags provide substantial protection against injuries to the upper torso, and head and neck in front collision [7]. However, airbags and seatbelts have not been shown to reduce the incidence of injuries to the lower extremities [2, 7–9]. Survival from potentially fatal crashes because of restraint systems may cause a relative increase in the number of disabling injuries. These injuries carry considerable societal costs, including health care expenditure, long-term and permanent disability, and loss of productivity. In some series, injuries to the lower extremities rank as the second most common injury among motor-vehicle occupants [7]. Injuries to the extremities increase hospital costs and the length of hospital stay, possibly because of multiple surgical procedures required to manage these injuries [10]. In our study population, the foot-fracture patients required significantly longer hospital stays, which were more than double the hospital stays of the nonfoot-fracture population. The ISS in the foot-fracture group is significantly higher than the non-footfracture group, reflecting a higher magnitude of body injury and the major body parts affected. These patients not only require a longer recovery time but also, due to foot injuries, may suffer a delay in early ambulation and subsequent placement into a rehabilitation facility and discharge from the hospital. Foot fractures may be an index for greater severity according to some authors [10]. Though this was not borne out in this study, the financial implications remained the same.

Severity of injury is frequently only moderate in patients sustaining injuries to their extremities. Injuries to the lower extremities have been shown to demand the highest health care expenditures in the first year following moderate-severity trauma. Forty per cent of the 1-year motor-vehicle trauma charges in Maryland, USA, resulted from lower-extremity injuries [10]. The relative increase in the incidence of lower-extremity fractures, which has resulted in escalation of health care costs, may only be controlled by better injury prevention. Length of hospital stay was significantly longer in the patients who sustained foot fractures. This finding parallels results from other studies that show extended hospital stays with increased operative procedures for patients sustaining foot fractures [10]. Injuries that are combined with foot fractures – such as pelvic fractures and facial injuries – may contribute to the increased morbidity, cost, and length of hospital stay for these injuries. The incidence of pelvic fractures and facial fractures were significantly higher in the foot-fracture group. Closed-head injuries were encountered more frequently in the non-foot-fracture group. The use of restraints and their association with these injuries were not specifically compared in this study. The distribution of pelvis and facial fractures in contradistinction to closed-head injuries may possibly be explained by the interaction between airbag and seatbelt restraints. In frontal crashes, airbags more than seatbelts may reduce head injury and the incidence of facial fractures; however, they have not shown a protective effect on pelvic fractures [11]. Injuries to the lower extremities occur within the currently accepted safety standards, which cover a change in velocity of less than 30 m.p.h. [12]. Vehicular–occupant-contact areas involved in the pathogenesis of lower-extremity injuries have been described. Contact with the instrument panel causes 44% of serious lower-extremity injuries. Moreover, 31% of these injuries result from occupant contact with the floor and the side interior [13]. In clinical and crash reconstruction correlations of lower-extremity injuries performed by Burgess et al. [9], 70% of the patients suffered foot fractures. In 57% of those fractures axial load was involved in the mechanism alone, or in combination with eversion (28%). Fifty-seven per cent of those foot fractures  1997 Blackwell Science Ltd, Foot and Ankle Surgery, 3, 199–203

FOOT FRACTURES

were produced by a mechanism of direct impact. The fractures described in that series mainly involved midfoot and metatarsal fractures. Yoganandan et al. [14] reported in detail axial load forces to the foot and ankle. Impact velocities at 6.7 m/s showed a 50% incidence of calcaneal fractures. Of the cadavers studied 100% sustained foot fractures at velocities above 7.6 m/s (approximately 25 km/h). Drivers seem to have an increased tendency lower-extremity injuries. Huelke et al. [13] found a total of 57% of drivers with severe lower-extremity injuries. In our study, drivers had an increased incidence of foot fractures. This fact might be related to the toe board, foot controls or steering assembly [14]. Body habitus and gender may contribute to the biomechanics of foot fractures [15, 16]. Females constituted only 39% of our motor-vehicle crash population but suffered 50% of the foot fractures. However, smaller female body size may be more responsible than gender in the incidence of lowerextremity fractures [16]. Further study of these areas of concern may result in improved prevention of lower-extremity injuries.

Conclusions Restraint devices reduce the incidence of head injuries, pelvic fractures, and facial fractures among motor-vehicle crash victims. However, the incidence of non-fatal injuries, such as foot fractures, are not lowered by restraint systems. The lack of protection of the lower extremities, specifically the foot, axial load forces, and direct contact or panel intrusion may be involved in the pathogenesis of lower-extremity injuries. More research is needed to evaluate this aspect of automobile safety. Foot fractures and associated injuries remain costly and a significant cause of morbidity and disability. As more occupants survive motor-vehicle crashes because of improved restraint systems, a better understanding of crash dynamics is necessary to reduce lower-extremity injuries.

Acknowledgement This study was supported in part by a grant from the Conemaugh Research Foundation, Pennsylvania, USA.

 1997 Blackwell Science Ltd, Foot and Ankle Surgery, 3, 199–203

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