In this retrospective study, we determined (long-term) clinical outcomes of patients that underwent BPAI repair following tibiofemoral trauma. Taking the number of observed BPAI patients, the studied 19-year period in two level 1 trauma centers and the large potential for limb loss into account, we determined that BPAI remains a rare and challenging surgical emergency. We compared outcomes of patients that received initial vascular repair (VF) to those that received initial temporary external stabilization of fractures and dislocations (BF) and found an overall primary limb salvage rate of 100% with comparable outcomes between the VF and BF groups.
Vessel-first and bone-first strategy
International guidelines regarding the management of lower extremity trauma do not provide unambiguous recommendations whether revascularization or bone stabilization should be performed first in tibiofemoral trauma patients with popliteal artery injury [
12,
19]. The Western Trauma Association guideline recommendation regarding management of the mangled extremity states that in hemodynamically stable patients, initial reduction of fractured bones using either splinting or traction fixation will alleviate kinking of the vasculature and improve subsequent perfusion. However, in case of vascular injury in addition to orthopedic injury in patients with isolated extremity injuries or limited associated injuries, no recommendations regarding a VF or BF strategy are made. In case of hemodynamic instability and an extremity which is deemed salvageable, initial use of an intraluminal shunt is recommended [
12].
As multiple studies emphasize the influence of total ischemia duration on clinical outcomes, initial revascularization is often preferred [
10,
20]. This VF strategy has been associated with good clinical outcomes [
21]. The absence of external fixation materials during a VF strategy may provide better popliteal artery exposure during surgery. During a damage-control approach in polytrauma patients, a VF strategy (utilizing intraluminal shunting) may be preferable as it reduces operating time. However, we speculate that initial bone stabilization (BF) may be preferred in patients with severe isolated orthopedic injuries, to prevent traction injuries to the vascular graft and to prevent sharp fracture elements from damaging the vascular graft. Furthermore, tibiofemoral alignment may aid the correct positioning and lengthening of the vascular graft.
In addition to current literature, we were able to compare both the VF and BF strategy in BPAI patients (mostly consisting of isolated lower extremity trauma patients) and determined that a BF strategy could be safely performed in those where primary osseous stabilization was deemed necessary.
Although a few studies have described external fixation before or after popliteal artery repair, the studied patients suffered mostly from penetrating (popliteal) arterial injuries in addition to blunt injuries [
22,
23]. Neither specifically studied popliteal artery injuries, since all lower extremity vascular injuries were combined. One of these studies, consisting of 17 lower extremity vascular injuries, made a recommendation regarding the optimal strategy, advocating initial revascularization over orthopedic stabilization [
22]. A retrospective study focusing strictly on blunt injuries to the popliteal artery identified multiple factors associated with limb salvage, of which prehospital delay > 6 h was frequent among amputees, but did not study the effects of a VF or BF strategy [
24].
Penetrating and blunt injuries to the popliteal artery result in different types of arterial damage (e.g., transection with free extravasation and tourniquet application vs. dissections and near-occlusions), caused by different injury mechanisms (e.g., knife/gunshot wounds vs. mechanical falls/crush injuries) with different associated injuries. Of these, BPAIs are associated with a higher frequency of secondary amputations, due to higher-energy trauma [
20]. Due to these differences in both the arterial injury and the associated injuries, the need for a VF or BF may be different. Therefore, the outcomes of these strategies for BPAI patients remained unknown thus far.
As the choice for initial management strategy in the studied institutions was mostly based on surgeon preference, we aimed to identify specific patient and injury characteristics that influenced that decision. Although we did not find significant differences between groups, specifically regarding associated tibiofemoral injuries such as the occurrence of tibial plateau fractures (p = 1.00), we speculate that specific injury characteristics have played a role in the decision to treat according to either the VF or BF strategy. This speculation, that lacks statistical power, is based on observed differences such as more high-energy mechanisms of injury in BF patients, a high median ISS in BF patients, and more severe tibial plateau fracture types in BF patients, which could imply more extensive orthopedic injuries to be present in BF patients.
Although median (IQR) total delay duration in the BF group of 6.8 h (4.0–7.5) was greater than the 5.5 h (4.0–8.5) in the VF group, total delay duration was not significantly different between groups (
p = 1.00). Median (IQR) in-hospital delay in the BF group of 2.7 h (1.0–3.0) and the VF group of 2.6 h (2.0–2.9) was not different, as well (
p = 0.82). When taking the total delay duration and population characteristics into account, we conclude that both the VF as well as the BF strategy have comparable good outcomes. We speculate that during treatment of BPAI patients with severe tibiofemoral fractures and dislocations, a BF strategy may be preferred in order to provide stability for the vascular repair. However, caution should be used when extrapolating these results to individual patients with other ischemia durations and total trauma burdens. In case of a longer total ischemic duration, irrespective of associated tibiofemoral injuries, a VF strategy (using intraluminal shunting if necessary) or a strategy where external fixation is preceded by vascular shunting before definite popliteal artery repair may be preferred, as total ischemia duration is a predictor for (secondary) amputation [
10,
20].
Long-term outcomes
Most patients received lower leg revascularization by popliteal artery bypass (59%) or interposition graft (33%), as transections and (severe) vessel-wall contusion limited endovascular treatment options. Therefore, these long-term outcomes are applicable to revascularization utilizing these surgical procedures. A total of 25 patients were available for long-term follow-up (93%), with a median (IQR) follow-up of 2.7 years (1.1–5.9). During this period, three vascular re-interventions were performed in these 25 patients, of which one was related to the reverse GSV bypass (4%). Excluding those that had re-interventions, no claudication complaints were observed. A total of 20 patients were started on ASA antiplatelet therapy (74%), mostly dosed 325 mg once daily, which was continued during the follow-up period. Using antiplatelet therapy, including ASA, as postoperative antithrombotic regimen to assure vascular patency, is in accordance with regimens of infrainguinal bypass surgery for (non-traumatic) peripheral arterial disease [
25,
26]. Based on these results, we conclude that popliteal artery bypasses and interposition grafts for BPAI, using reversed GSV grafting in combination with antiplatelet therapy, appear to result in good vascular patency after a follow-up period of almost 3 years. Larger studies focusing on complications, re-interventions, and long-term vascular patency should be performed to determine if long-term outcomes are similar to the ones described.
Limitations
Our study has several limitations. First, this was a retrospective study with a small number of patients. Although our results indicate comparably good outcomes between the VF and BF strategy for BPAI, larger studies are required to determine if (long-term) outcomes are similar to the ones we found. Of course, this is limited by the rare occurrence of these injuries and suggests that a multi-institutional effort may be needed for a larger study. In addition, the retrospective identification of patients during a 19-year period may potentially have resulted in missing cases.
Although no primary amputations were observed in our cohort, literature states that BPAIs are associated with high amputation rates. We speculate that this difference may be explained by undiagnosed BPAIs among the polytrauma patient population that did not survive emergency surgery (e.g., for intra-cranial or abdominal bleeding) and did not receive CTA scanning/peri-operative angiography (due to hemorrhagic shock). Polytrauma patients that required primary amputation of their mangled extremities due to the additional high total trauma burden may have had undiagnosed BPAIs, as well. This form of selection bias/survivorship bias may have resulted in better reported outcomes. Second, as patients received treatment according to the VF or BF strategy by surgeon preference (rather than randomization), selection bias is likely to be present. Although we speculate that patients with more severe orthopedic injuries were treated according to the BF strategy, we were unable to illustrate these differences with statistical significance. These differences may have been present and possibly have affected outcomes. Third, we were unable to accurately determine total ischemia duration, since the operative records did not literally mention the moment in time where an anastomosis was completed, and clamps were released. We, therefore, had to use total delay duration (time of injury—operating room arrival time) as the most accurate substitute for total ischemia duration. Fourth, as clinical outcomes of a VF or BF strategy for BPAI management are highly dependent on total ischemia duration (therefore ischemic damage to the lower leg), our results cannot be seen separate from the observed total delay durations. Caution should be used when extrapolating the results of both strategies to a setting with different (pre-)hospital trauma care logistics.