Abstract
Objective:
To evaluate whether the presence of a concurrent fibula fracture in low-velocity ballistic tibia fractures was associated with increased rates of vascular injury and compartment syndrome. We hypothesized that ballistic tibia fractures with an associated fibula fracture would have higher rates of vascular injury and compartment syndrome than isolated ballistic tibia fractures.
Design:
Retrospective cohort study.
Setting:
Single academic Level 1 trauma center.
Patients:
Adult patients aged 18 years or older who underwent surgical fixation for low-velocity ballistic tibia fractures between 2014 and 2024 were included. Patients with documented rifle or shotgun injuries were excluded.
Intervention:
Patients were stratified by fracture pattern into isolated tibia fracture and combined tibia–fibula fracture groups.
Main Outcome Measurements:
Primary outcomes were vascular injury identified on computed tomography angiography and compartment syndrome, defined by documented clinical diagnosis treated with fasciotomy.
Results:
Of 34 patients with ballistic tibia fractures, 11 (32.4%) had a concomitant fibula fracture. The tibia–fibula fracture group had a significantly higher rate of vascular injury than the isolated tibia fracture group (72.7% [8/11] vs. 8.7% [2/23], P < 0.001). Compartment syndrome occurred in 27.3% (3/11) of patients with tibia–fibula fractures and 4.3% (1/23) of patients with isolated tibia fractures; this difference was not statistically significant (P = 0.089).
Conclusion:
Among patients with low-velocity ballistic tibia fractures, the presence of a concomitant fibula fracture was associated with a higher rate of vascular injury.
Level of Evidence:
III.
Keywords: ballistic tibia fracture, vascular injury, arterial injury, compartment syndrome, ballistic
Introduction
Tibia fractures account for 8%–31% of all ballistic fractures, making the tibia one of the long bones most frequently affected.1–3 In civilian settings, most firearm-related skeletal trauma is caused by low-velocity projectiles.4 Gunshot injuries of the tibia carry a relatively high risk of vascular injury and acute compartment syndrome compared with ballistic fractures at other anatomical sites.3,5
Although ballistic tibia fractures have been recognized as high-risk injuries, the effect of a concurrent fibula fracture remains unexplored. Anecdotally, we observed that ballistic tibia–fibula fractures present with vascular injury and develop compartment syndrome at high rates.
The purpose of this study was to evaluate whether a concomitant fibula fracture was associated with increased rates of vascular injury and compartment syndrome in patients with low-velocity ballistic tibia fractures. We hypothesized that in low-velocity ballistic tibia trauma, tibia–fibula fractures would have significantly higher rates of vascular injury and compartment syndrome than isolated tibia fractures.
Methods
Ethical approval for this study was provided by the University of California, Davis, Institutional Review Board (Protocol No. 2139637-1: Principal Investigator Sean T. Campbell, MD) and this study was conducted in accordance with the Declaration of the World Medical Association. The requirement for informed consent was waived because of the retrospective nature of the study. A retrospective review was conducted of all patients who sustained gunshot-related fractures at a Level I trauma center between January 1, 2014, and December 31, 2024. Inclusion criteria consisted of patients aged ≥18 years with a ballistic tibia fracture, classified as 41 A–C, 42 A–C, and 43 A–C according to Arbeitsgemeinschaft für Osteosynthesefragen/Orthopedic Trauma Association (AO/OTA) classification.6 Patients who did not undergo surgical fixation and patients with documented rifle or shotgun injuries were excluded. All fractures were confirmed by review of radiographic images.
Patient demographic variables, including age at the time of injury, sex, body mass index (BMI), smoking history, and diabetes status, were recorded. Injury characteristics, including documented type of firearm causing injury, fracture fixation method, type and number of injured vessels, vascular procedures, and AO/OTA fracture classification, were documented.
Patients were assigned to isolated tibia fracture or tibia–fibula fracture groups. Primary outcomes were (1) vascular injury on computed tomography angiography (CTA) and (2) compartment syndrome. During the study period, the institution's standard protocol required that all patients with ballistic lower-extremity injuries undergo CTA; accordingly, all patients included in this study underwent CTA. Vascular injury was defined as the presence of one or more of the following findings in the injured limb on CTA: active contrast extravasation, pseudoaneurysm, intimal injury (intimal flap or dissection), or arterial occlusion/transection (abrupt contrast cutoff with or without distal reconstitution). Compartment syndrome was defined as a documented clinical diagnosis with fasciotomy.
A subanalysis was conducted to evaluate outcomes in patients with diaphyseal tibia fractures. Patients identified as having diaphyseal tibia fractures on radiographs were assigned to tibia–fibula or isolated tibia fracture groups, and rates of compartment syndrome and vascular injury were compared.
Descriptive statistics were used to compare variables between groups. Categorical variables were analyzed with two-sided Fisher exact tests. P < 0.05 was considered statistically significant. All statistical analyses were performed using RStudio (Posit Team, 2024).7
Results
Forty-five patients with ballistic tibia fractures were screened. Five patients (11.1%) were excluded because of documented rifle or shotgun injuries, and 6 patients (13.3%) were excluded because of nonoperative treatment, leaving 34 patients for analysis. The mean age was 30.6 ± 9.2 years, and 32 patients (94.1%) were male (Table 1). Twenty-three patients (67.6%) sustained isolated tibia fractures (Fig. 1), and 11 (32.4%) sustained tibia–fibula fractures (Fig. 2).
Table 1.
Patient Demographics and Injury Characteristics
| Overall | Isolated Tibia | Tibia–Fibula | |
| Patients, n (%) | 34 (100%) | 23 (67.6%) | 11 (32.4%) |
| Age, mean ± SD | 30.6 ± 9.2 | 30.2 ± 9.1 | 30.9 ± 9.5 |
| BMI (kg/m2), mean ± SD | 26.7 ± 6.0 | 25.8 ± 7.1 | 27.2 ± 5.5 |
| Male sex, n (%) | 32 (94.1%) | 22 (95.7%) | 10 (90.9%) |
| Smoking, n (%) | 24 (70.6%) | 14 (60.9%) | 10 (90.9%) |
| Diabetes, n | 0 | 0 | 0 |
| AO/OTA Classification, n | |||
| 41A | 0 | 0 | 0 |
| 41B | 3 | 3 | 0 |
| 41C | 5 | 5 | 0 |
| 42A | 0 | 0 | 0 |
| 42B | 1 | 1 | 0 |
| 42C | 24 | 13 | 11 |
| 43A | 0 | 0 | 0 |
| 43B | 0 | 0 | 0 |
| 43C | 1 | 1 | 0 |
| Fixation method, n (%) | |||
| Intramedullary nail | 24 (70.6%) | 14 (60.9%) | 10 (90.9%) |
| Plate | 9 (26.5%) | 8 (34.8%) | 1 (9.1%) |
| Screws | 1 (2.9%) | 1 (4.3%) | 0 (0%) |
| Vascular injury, n (%) | 10 (29.4%) | 2 (8.7%) | 8 (72.7%) |
| Number of lower leg vessels injured, n | |||
| 1 | 5 | 1 | 4 |
| 2 | 3 | 0 | 3 |
| 3 | 2 | 1 | 1 |
| Vessels injured, n | |||
| Anterior tibial artery | 8 | 2 | 6 |
| Peroneal artery | 6 | 1 | 5 |
| Posterior tibial artery | 3 | 1 | 2 |
| Compartment syndrome, n (%) | 4 (11.8%) | 1 (4.3%) | 3 (27.3%) |
AO/OTA, Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association Classification; BMI, body mass index.
Figure 1.
Case example of an isolated tibia fracture after a low-velocity firearm injury to the left leg. Initial radiographs (A) showed a comminuted fracture of the tibia shaft. There was no evidence of vascular injury on CTA. The hospital course was uneventful, and definitive fixation was performed via open reduction, internal fixation, and intramedullary nailing (B).
Figure 2.
Case example of a tibia–fibula fracture after a low-velocity firearm injury to the left leg. Initial radiographs (A) showed comminuted fractures of the tibia and fibula. CTA demonstrated vascular injury involving the anterior tibial, posterior tibial, and peroneal arteries. Because of clinical signs of compartment syndrome, an emergent four-compartment fasciotomy was performed. The patient underwent revascularization, and an external fixator was placed for provisional stabilization (B). Definitive fixation was subsequently achieved via open reduction, internal fixation, and intramedullary nailing (C).
Overall, 10 of 34 patients (29.4%) had a vascular injury. The rate of vascular injury was significantly higher in patients with tibia–fibula fractures than in those with isolated tibia fractures (72.7% [8/11] vs. 8.7% [2/23], P < 0.001) (Table 2).
TABLE 2.
Comparison of Rates of Vascular Injury and Compartment Syndrome
| Isolated Tibia | Tibia–Fibula | P | |
| Vessel injury | 2/23 (8.7%) | 8/11 (72.7%) | <0.001 |
| Compartment syndrome | 1/23 (4.3%) | 3/11 (27.3%) | 0.089 |
| Isolated tibia diaphysis | Tibia–fibula diaphysis | ||
| Vessel injury | 2/15 (13.3%) | 8/11 (72.7%) | 0.004 |
| Compartment syndrome | 1/15 (6.7%) | 3/11 (27.3%) | 0.28 |
Boldface indicates statistical significance at P < 0.05.
Of the 10 patients with vascular injuries to the lower leg, 5 had a single vessel injury, 3 had a two-vessel injury, and 2 had a three-vessel injury. The anterior tibial artery was the most frequently injured vessel, occurring in 8 of 10 cases, followed by the peroneal artery in 6 of 10 cases, and the posterior tibial artery in 3 of 10 cases. Two patients required revascularization. One of these patients had a tibia–fibula fracture, and the other had an isolated tibia fracture. Both patients had three-vessel injuries and developed compartment syndrome.
Compartment syndrome occurred in 4 of 34 patients (11.8%), all of whom had a vascular injury on CTA. The rate of compartment syndrome did not differ significantly between patients with combined tibia–fibula fractures and those with isolated tibia fractures (27.3% vs. 4.3%, P = 0.089).
Of the 34 fractures, 26 (76.5%) were diaphyseal and 8 (23.5%) involved the proximal tibia (AO/OTA 41A-C). None of the proximal tibia fractures had an associated fibula fracture, vascular injury, or compartment syndrome; all fibula fractures and all vascular injuries and instances of compartment syndrome occurred in the diaphyseal tibia fracture subgroup. Compared with proximal tibia fractures, diaphyseal fractures had a significantly higher rate of fibula fractures (42.3% vs. 0%, P = 0.034) but did not have significantly higher rates of vascular injuries (38.5% vs. 0%, P = 0.072) or compartment syndrome (15.4% vs. 0%, P = 0.55). In the subset of 26 diaphyseal fractures, the association between tibia–fibula fractures and vascular injury remained significant: 8 of 11 patients (72.7%) with diaphyseal tibia–fibula fractures sustained vascular injury, compared with 2 of 15 patients (13.3%) with isolated diaphyseal tibia fractures (P = 0.004). There was no significant difference in compartment syndrome rates between these 2 diaphyseal cohorts (Table 2).
Discussion
In this retrospective series of 34 surgically treated low-velocity ballistic tibia fractures, a concomitant fibula fracture was significantly associated with vascular injury but not with compartment syndrome. A focused subanalysis of the 26 diaphyseal fractures demonstrated the same pattern: the rate of vascular injury was significantly higher in tibia–fibula fractures, whereas compartment syndrome rates did not differ.
Prior literature has established that there is a high risk of vascular injury in ballistic tibia fractures. However, to our knowledge, no prior work has compared isolated tibia fractures with combined tibia–fibula fractures. In this cohort, tibia–fibula fractures were associated with a higher rate of vascular injury than isolated tibia fractures in civilian ballistic trauma. These findings suggest that the elevated vascular injury risk described in ballistic tibia trauma may be particularly associated with combined tibia–fibula fracture patterns. However, most vascular injuries in this cohort did not require revascularization, which is important context when interpreting the clinical significance of the observed association.
The overall vascular injury rate of ballistic tibia fractures in our cohort (29.4%) exceeded the 14.8% recently reported by Lee et al.8 This difference may reflect our restriction to surgically treated fractures, which excluded less severe injuries, and the institutional protocol of routine CTA for ballistic lower leg injuries, which may have increased detection. Lee et al8 did not stratify by fibula involvement. In the present study, isolated tibia fractures had a lower vascular injury rate (8.7%) than Lee et al.'s8 overall rate, whereas tibia–fibula fractures had a higher vascular injury rate (72.7%), reinforcing fibula involvement as a marker of vascular risk in ballistic tibia trauma.
In this study, 80% of patients with vascular injuries had involvement of the anterior tibial artery. This pattern may help explain the higher rate of vascular injury observed in tibia–fibula fractures. One possible explanation is that projectiles causing combined tibia–fibula fractures traversed the interosseous space, placing the anterior tibial artery at particular risk because of its anatomic course. This interpretation is also consistent with the expected injury pattern of lower-velocity projectiles, which tend to produce focal injury along the projectile path rather than the larger temporary cavitation and broader soft tissue disruption characteristic of high-velocity injuries.9,10 However, because of the retrospective design, the exact mechanism of vessel injury could not be determined in every case. Vessel injuries may have resulted from direct projectile injury, adjacent osseous fragment injury, or local soft tissue disruption.
These findings should be interpreted within the broader framework of vascular assessment in extremity trauma. Clinical evaluation for hard and soft signs of vascular injury remains the foundation of assessment, with adjunctive testing such as ankle-brachial index (ABI) used when appropriate and CTA reserved for cases in which advanced imaging is warranted. Because CTA was obtained routinely at our institution, our findings should not be interpreted as supporting routine CTA for all ballistic tibia fractures.
The overall compartment syndrome rate of 11.8% aligns with previously reported rates of 11.6% by Meskey et al and 15.9% by Prather et al.3,11 We observed a higher, but nonsignificant, rate of compartment syndrome in tibia–fibula fractures compared with isolated tibia fractures (27.3% vs. 4.3%, P = 0.089). Given there were only 4 instances of compartment syndrome, this analysis was underpowered.
Meskey et al also reported higher compartment syndrome risk with proximal ballistic tibia fractures. In our cohort, no proximal tibia fractures (n = 8) had vascular injury or compartment syndrome; all events occurred in diaphyseal fracture patterns. This divergence may reflect the small sample size or the absence of fibula fractures in our proximal tibia subgroup, which in this series was associated with vascular injury risk.
Several limitations must be acknowledged in interpreting the results. The retrospective, single-center design limited external generalizability and introduced potential selection bias toward patients who were more severely injured and who required operative intervention. The modest sample size of 34 patients, although adequate to detect the large effect size observed for vascular injury, limited statistical power. The retrospective design was also inherently limited by the potential for inaccurate or incomplete reporting at the time of care. Accordingly, the exact mechanism of fracture could not be determined with absolute certainty in every case, including whether a fracture resulted directly from the projectile or from a secondary mechanism such as a fall after injury. In addition, projectile velocity and firearm type could not be definitively established in all cases because classification relied on medical documentation rather than direct confirmation of the weapon or ammunition. Exclusion of documented rifle and shotgun injuries, although necessary to maintain a more homogeneous study population, may also limit the applicability of these findings to other ballistic trauma scenarios. The reliance on CTA for vascular injury detection may have led to the identification of injuries of uncertain clinical significance. Furthermore, the diagnosis of compartment syndrome can be subjective and has been shown to vary depending on the surgeon,12 potentially leading to under- or overreporting.
In conclusion, among low-velocity ballistic tibia fractures, the presence of a concomitant fibula fracture was associated with a higher rate of vascular injury. This fracture pattern may help identify patients at increased vascular risk and prompt careful vascular evaluation.
Data availability statement
The data that support the findings of this study are available from the corresponding author upon reasonable request, subject to institutional review board and privacy considerations.
Footnotes
Potential conflicts of interest: J.C.W., A.S.R., W.S.M., D.D.-O., and S.T. have no conflicts of interest. E.F. has received consulting fees from Synthes. G.L.S. has received professional fees from Synthes. M.A.L. has received consulting fees from Synthes, Osteocentric, and Globus and serves as a board member for the AO Foundation. A.M.S. has received consulting fees from Stryker, Arthrex, and Synthes and served on the Program committee of OneAO. S.T.C. has received consulting fees from Synthes and Smith and Nephew and research support from Takeda Pharmaceuticals.
Source of funding: None.
Contributor Information
Amritpal S. Randhawa, Email: amsrandhawa@health.ucdavis.edu.
Westin Scott Mace, Email: wsmace@health.ucdavis.edu.
David Dallas-Orr, Email: ddallasorr@health.ucdavis.edu.
Shannon Tse, Email: sstse@health.ucdavis.edu.
Ellen Fitzpatrick, Email: efitzpatrick@health.ucdavis.edu.
Gillian L. Soles, Email: glsoles@health.ucdavis.edu.
Mark A. Lee, Email: marlee@health.ucdavis.edu.
Augustine M. Saiz, Email: amsaiz@health.ucdavis.edu.
Sean T. Campbell, Email: stcampbell@health.ucdavis.edu.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request, subject to institutional review board and privacy considerations.