Colour Doppler sonography in the preoperative assessment of the vascular pedicle from the anterolateral thigh flap: proposal for a mathematical formula to predict pedicle length

Assessment of the Length of the Pedicle of the Anterolateral Thigh Flap

Purpose To estimate the length of the pedicle of the anterolateral thigh flap (ALT) and to assess how this length corresponds with the distances between the anatomical landmarks. Methods The study group consisted of patients who underwent computed tomography angiograms ranging minimally from the anterior superior iliac spine (ASIS) superiorly and tibia inferiorly. In the study we included 44 patients. In the axial window we identified single scans with (1) ASIS, (2) the apex of the greater trochanter, (3) the origin of the descending branch of the lateral femoral circumflex artery (LFCA), (4) the superolateral corner of the patella, (5) knee joint gap. Knowing the slice thickness in every patient and the difference in scan number we measured (A)-the distance between the scan (1) and the scan (4). This distance (A) represented the length of the line connecting ASIS and the superolateral corner of the patella (AP line). Next, we identified (6) the midpoint of the distance (A). Next we measured (B)-the distance between the scan (2) and the scan (5) and (C)-the distance between the scan (3) and the midpoint of the AP line (6). Results Mean distances between the scans were: (A) 45.34 cm (SD=4.14), (B) 43.12 cm (SD=4.08), (C) 11.69 cm (SD=1.62). There was low positive correlation between the distance (A) and the distance (C) (rs=0.43) and moderate positive correlation between the distance (B) and the distance (C) (rs=0.53). Conclusion Our study suggests that the mean estimated length of the ALT flap pedicle is 11.69 cm and that it positively correlates with the length of the femur and the length of the AP line.

Initial Investigation of Clinical Value of Noise-Optimized Virtual Monoenergetic Images Derived From Dual-Energy Computed Tomography Angiography in Preoperative Perforator Planning of Anterolateral Thigh Flap Transplantation

OBJECTIVE

To objectively and subjectively assess the image characteristics of noise-optimized virtual monoenergetic images [MEI (+)] and polyenergetic images (PEIs) from dual-energy computed tomography angiography and then to explore the clinical value of the optimal MEI (+) in preoperative perforator planning of anterolateral thigh (ALT) flap transplantation.

METHODS

Sixteen patients (32 thighs) who underwent lower extremity run-off dual-energy computed tomography angiography for planning ALT flap transplantation were enrolled. One standard PEI and 5 MEI (+) in 10-keV intervals (range, 40-80 keV) were reconstructed. First, we compared the image quality subjectively (branch order, image quality, and vascular network continuity) and objectively (vascular attenuation, image noise, signal-to-noise ratio, and the contrast-to-noise ratio). Then, we compared the clinical value (number, type, source artery, pedicle length, caliber, and location of all sizable perforators) between the optimal MEI (+) and PEI groups.

RESULTS

The 40-keV MEI (+) was rated superior subjective and objective image quality metrics to PEI (all P < 0.001). Compared with PEI, 40 keV MEI (+) increased the number of visible perforators, the percentage of perforators with identifiable types, and the measurable length of perforator pedicle (all P < 0.001).

CONCLUSIONS

We recommend 40 keV MEI (+) for the visualization of perforators and their contribution to the selection and location of suitable perforators in preoperative planning for ALT flaps.

[Clinical application of computed tomographic angiography in predicting the vascular pedicle length of the proximally-based anterolateral thigh flap]

OBJECTIVE

To explore the reliability and effectiveness of prediction of the pedicle length of the proximally-based anterolateral thigh (pALT) flap which was used to repair the defects following the resection of various malignant tumors using computed tomographic angiography (CTA).

METHODS

The clinical data of 12 patients who met the selection criteria by using pALT flap to repair wounds left after malignant tumor resection between June 2015 and December 2020 were retrospectively analyzed. There were 5 males and 7 females; the age ranged from 16 to 80 years, with an average age of 54.4 years. After tumor resection, the soft tissue defect ranged from 15 cm×5 cm to 30 cm×12 cm; defect sites included 4 cases of lower abdomen, 3 cases of groin, 2 cases of thigh, and 3 cases of buttocks. Preoperative CTA was used to obtain the location information of the descending branch of the lateral femoral circumflex artery and its perforators by maximum density projection, and the length of the pedicle of pALT flap was estimated. Fasciocutaneous flap (5 cases) or myocutaneous flap (7 cases) were cut during operation to repair the defect, and the size of flap ranged from 20 cm×7 cm to 30 cm×12 cm. The donor site of thigh was directly sutured (11 cases) or repaired with skin graft (1 case). Bland-Altman analysis was used to detect the consistency between the pALT flap vascular pedicle length estimated by CTA and the pALT flap vascular pedicle length actually obtained during operation.

RESULTS

One case had distal blood supply disturbance of the flap and was repaired with skin graft after debridement; the remaining 11 flaps survived. All donor and recipient incisions healed by first intention. All 12 cases were followed up 1-12 months, with an average of 4.3 months. One patient died of pelvic tumor recurrence at 6 months after operation, and no tumor recurrence was found in the other patients. Preoperative CTA estimated that the length of pALT flap vascular pedicle was 9.3-24.7 cm, with an average of 14.7 cm; the actual length of pALT flap vascular pedicle was 9.5-25.0 cm, with an average of 14.8 cm. Bland-Altman analysis showed that there was no significant difference between the pALT flap vascular pedicle length estimated by CTA before operation and the pALT flap vascular pedicle length actually obtained during operation, and the average difference was 0.1 (95% consistency limit: -0.89, 0.74), indicating that they had good consistency.

CONCLUSION

CTA can be accurately used to localize the perforator and predict the possible pedicle length of the pALT flap. When performing a pALT flap surgery, preoperative CTA is helpful for surgeons to make a preliminary assessment of the difficult of the operation. The time for exploration of perforators and dissection of the vascular pedicle, and complications can be reduced, and the safety of the operation can be improved.

A Case Report of Aberrant Vascular Anatomy of the Anterolateral Thigh Flap

Soft tissue free flaps are used for a variety of head and neck reconstructions. The anterolateral thigh (ALT) flap has been a versatile tool in head and neck reconstruction since the mainstream use of microvascular anastomosis for free tissue transfer. The ALT flap has a known history of variable vascular anatomy. Most of this variability lies within perforator anatomy and vascular aberrations distal to the lateral circumflex femoral artery (LCF). Few vascular aberrancies have been described proximal to the LCF. Here we present a case of report of an ALT whose arterial vascular pedicle was a branch directly off the femoral artery. The case highlights an unusual anatomical variant of the ALT flap, and the importance of a thorough and meticulous dissection.