In this study, CTA accurately predicted the dimensions of the fibula, the origin of the peroneal artery, and the location and course of visible perforators, but less accurately predicted perforator size. Although CTA fibula length and peroneal artery origin measurements were significantly different in comparison to intraoperative findings by the t-test, our surgeons found that the <1 cm mean absolute value differences for these measurements were still accurate enough to facilitate execution of the fibula flap harvest. The anatomic information provided by CTA agrees with previous studies in regards to the distribution of peroneal artery perforators along the lower leg.8,27,37
Most importantly, the information provided by CTA influenced our surgeons to modify the reconstructive strategy in 25.0% of the cases, resulting in more precise skin paddle placement and avoidance of potentially compromised extremity perfusion in two patients.
In one of the earliest descriptions of the use of a free fibula osteocutaneous flap for mandible reconstruction, Hidalgo judged the skin island perfusion to be poor enough to justify excision of the skin island in 3 of 4 patients.2
Therefore, Hidalgo cautioned against reconstructing mandibles that had significant soft tissue loss with osteocutaneous free fibula flaps. He also stated that “angiography does not allow adequate preoperative study of skin blood supply, although it may be useful to confirm that the peroneal artery is present, free of disease, and not the dominant source of blood supply to the distal leg.”
The current recommendations for use of preoperative angiography prior to free fibula flap harvest have their origins in Hidalgo’s original study. More recent studies have specifically explored the utility of preoperative angiography in free fibula flap reconstruction, with contradictory conclusions, but all of these studies focused on the macrovascular patency of the infrapopliteal trifurcation rather than the status of the cutaneous perforators.10,30,31
Studies by Lutz et al.30
and Disa et al.31
discouraged the routine use of preoperative angiography and recommended clinical vascular examination as the primary means of evaluating the fibula donor site, reserving preoperative angiography for patients with abnormal pulse examinations. A study by Blackwell,10
however, reported that the surgical plan was changed in 21% of patients who underwent preoperative angiography prior to oromandibular reconstruction and, thus, recommended the routine use of preoperative vascular imaging to avoid “a potentially catastrophic complication.” It is important to note, however, that all three of these studies were based on the results of standard digital subtraction angiography, not CTA.
The advent of CTA has drastically decreased the indications for traditional digital subtraction angiography, an invasive technique that requires intravascular contrast media injection via arterial catheterization, which can result in arterial laceration, pseudoaneurysm, or arterovenous fistula. Compared with digital subtraction angiography, CTA has not only been shown to be effective in the diagnosis of peripheral arterial disease but also avoids the potential complications associated with invasive arterial catheterization, costs less, requires less time, and may expose patients to less ionizing radiation.38
Therefore, CTA has become the preferred modality for imaging the infrapopliteal vessels in patients with peripheral arterial disease, and yet, studies describing the clinical utility of CTA for fibula flap planning are lacking, in that they provide inadequate data regarding the perforators or no validating intraoperative data.11,27,39,40
On the basis of our findings and previous studies, we find it difficult to definitively recommend that all patients undergo CTA prior to fibula flap harvest for the sole purpose of verifying adequate perfusion to the foot.10–12,28,39
We agree with previous authors’ recommendations to selectively perform preoperative angiography on any patient with an abnormal clinical vascular exam or a history suggestive of arterial insufficiency.8,30,31
We do prefer CTA to standard digital subtraction angiography for identifying peripheral arterial disease, not only for the reasons already discussed but also because it provides useful information about perforator and fibula anatomy.41
However, our data suggest that CTA, like conventional angiography, does occasionally contradict the physical examination, findings that agree with previous studies cautioning against relying solely on clinical vascular examination as a means of screening for variant anatomy.11,12,27,39
Almost a third of our patients had abnormal clinical vascular examinations, yet we found that the clinical examination alone accurately predicted a clinically relevant vascular anomaly that would have affected surgical decision-making in only one of the 40 patients in our study. Following our experience with CTA, some of our surgeons now routinely order preoperative CTAs for all patients prior to fibula flap harvest, but most selectively order CTAs in patients with abnormal pulse exams or clinical signs of peripheral arterial disease or when knowledge of the vascular or bony anatomy is crucial to the reconstructive plan (e.g., when multiple skin paddles are needed or for precise planning of osteotomies for computer-assisted design/medical modeling).
Even in patients with a low index of suspicion for vascular insufficiency by clinical examination, we found that our surgeons changed their surgical plans based on CTA results not to avoid distal ischemia or to improve flap survival but to more precisely design their flaps. For example, knowing the peroneal arterial anatomy facilitated accurate location of the proximal osteotomy, such that optimal exposure of the peroneal artery origin was achieved without excising more bone than necessary or making multiple cuts for exposure. Knowledge of the perforator anatomy was useful in flap design, helping us to determine ahead of time if an additional free or locoregional flap might be needed. Rather than spending excessive time dissecting proximal musculocutaneous perforators that took an indirect course through the soleus muscle, we utilized CTA-visualized distal perforators that took a more direct septocutaneous course to the overlying skin.6
However, since our study lacked a control group of patients who did not receive CTA, we were unable to determine whether or not CTA actually saves time in the OR, as has been claimed for abdominal-based free flaps.23
This study’s findings corroborate our prior clinical study8
demonstrating that most patients have at least two useful perforators in a bimodal distribution (proximal and distal), although a subset of patients’ legs have only one perforator and some have none. For situations in which precise anatomic information is critical, CTA enables an even higher level of patient-specific flap design than can be realized by population-based anatomic mapping. While CTA was not particularly accurate in classifying the size of the perforators, precise size determination is probably not critical, as fibula flap perforator selection is primarily based on perforator location, and even small perforators are usually adequate to supply most skin paddles used in head and neck reconstruction.
Critics have raised questions regarding the cost and safety of CTA mapping and suggested alternative modalities to avoid the negative characteristics associated with CTA.42–46
The current Medicare reimbursement for a CTA of the lower extremities in Texas is $451.69. Laser-assisted indocyanine green (ICGN) imaging avoids radiation exposure, demonstrates cutaneous perforasomes, facilitates optimal skin island position, and requires a minimal volume of contrast media.43–45,47,48
However, ICGN cannot visualize the macrovascular (tibio-peroneal) and fibula bony anatomy and is only available in the operating room, precluding preoperative planning. Although magnetic resonance angiography (MRA) avoids radiation exposure, CTA has been shown to be superior to MRA for perforator mapping.46