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Factors Affecting Volume Change of Anterolateral Thigh Flap in Head and Neck Defect Reconstruction

Factors Affecting Volume Change of Anterolateral Thigh Flap in Head and Neck Defect Reconstruction



Factors Affecting Volume Change of Anterolateral Thigh Flap in Head and Neck Defect Reconstruction




Journal of Oral and Maxillofacial Surgery, 2020-11-01, Volume 78, Issue 11, Pages 2090-2098, Copyright © 2020 American Association of Oral and Maxillofacial Surgeons


Purpose

The anterolateral thigh flap (ALTF) volume will decrease over time after surgery. We measured and identified the risk factors for postoperative volume changes in the ALTF.

Materials and Methods

We designed and performed a retrospective cohort study of patients who had undergone reconstruction of oral and maxillofacial defects using ALTFs at the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology from June 2012 to December 2018. We measured the volume of the ALTFs at 1, 3, 6, 12, and 24 months postoperatively; the flap volume at 1 month postoperatively was taken as the baseline. The primary outcome variables were the residual ALTF rates at 3, 6, 12, and 24 months postoperatively, defined as the ratio between the present volume at each month and at baseline. The primary predictor variables were the clinical variables that might be associated with ALTF volume loss. Descriptive and bivariate statistics were computed, and the P value for statistical significance was set at ≤ .05.

Results

The sample included 70 subjects with a mean age of 53.8 years (46 men and 24 women). The postoperative residual rates at 3, 6, 12, and 24 months were 72.3, 69.0, 67.9, and 68.7%, respectively, of the baseline volume. The use of postoperative radiotherapy ( P < .01) and low body mass index (BMI; P = .006) were significantly associated with postoperative ALTF volume loss.

Conclusions

The results of the present study suggest that ALTF volume shrinkage mainly occurs within 6 months postoperatively and that postoperative radiotherapy and a low BMI are risk factors for volume loss. Overcorrection should be performed to account for the shrinkage of ALTFs, and postoperative nutrition management is important to avoid ALTF volume loss.

Simultaneous reconstruction for extensive tissue defects after tumor ablation has been recommended to minimize functional and esthetic problems in patients undergoing oral and maxillofacial surgery. , With the tremendous improvements in microsurgical techniques and instruments during the past 3 decades, free flap transfer has become a standard and reliable approach for oral and maxillofacial defect reconstruction. The anterolateral thigh flap (ALTF) has many advantages, including the consistent anatomy of the main pedicle and the variable thickness and volume. Thus, the ALTF can be contoured according to the extent of the defect. The ALTF has become increasingly popular among surgeons since it was described in 1984 by Song et al and has been regarded as a versatile flap for the reconstruction of oral and maxillofacial defects by some surgeons.

A soft tissue flap with appropriate volume is crucial for functional and esthetic outcomes in oral and maxillofacial defect reconstruction. , However, postoperative ALTF volume loss has been commonly observed in clinical practice, which can markedly affect speech, swallowing, and patient appearance. , Therefore, a flap larger than the actual defect might be required to compensate for atrophy of the flap itself.

Although a few studies have reported on the postoperative volume change of ALTFs and the relevant risk factors, unanimous consensus still has not been reached. To the best of our knowledge, no research with a large sample size has been conducted with long-term continuous follow-up data available regarding the postoperative volume change of ALTFs. The purpose of the present study was to measure and identify the risk factors associated with the postoperative volume changes of ALTFs. We hypothesized that the postoperative ALTF volume would decrease over time and that some clinical factors would be risk factors. The specific aims of the present study were to estimate the continuous volume change of ALTFs and identify the risk factors for the volume loss.


Materials and Methods


Study Design

To address the research purpose, we designed and performed a retrospective cohort study. The study population included patients who had undergone reconstruction of oral and maxillofacial defects using ALTFs at the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology from June 2012 to December 2018. All the surgeries had been performed by a single surgical team. The inclusion criteria were as follows: 1) reconstruction of oral and maxillofacial defects using ALTFs; 2) patient age of 18 years or older; 3) the use of an ALTF harvested without a muscular component; 4) postoperative computed tomography (CT) scans available; and 5) no signs of regional infection on clinical examination or CT scan at 1 month postoperatively. The exclusion criteria were as follows: 1) reconstruction had been performed using a flap other than the ALTF or concurrent with an ALFT; 2) the development of local recurrence during the follow-up period; and/or 3) performance of secondary reconstruction or excisional correction of the flap.


Measurement Procedure

Routine CT scans of the head and neck region were performed at 1, 3, 6, 12, and 24 months postoperatively (field of view, 20 cm; pitch, 1.0; slice, 1.25 mm; 120 × 280 mA). The CT data were imported into iPlan CMF, version 3.0.5, software (BrainLAB, Feldkirchen, Germany) in DICOM (Digital Imaging and Communications in Medicine) format. First, the border of the flap on each axial CT image was manually traced in iplan CMF, version 3.05. Next, the software was used to automatically generate the 3-dimensional model and calculate the flap volume ( Fig 1 ). All the CT data were measured by 2 of us (interclass correlation coefficient, 0.98), and the mean value was recorded. For cases in which the difference between the measurements was more than 10%, an additional measurement was obtained, and the mean value was again calculated. Using the 1-month postoperative volume as the baseline, the residual ALTF rates at 3, 6, 12, and 24 months postoperatively were calculated.

Computed tomography (CT) images showing contouring and 3-dimensional reconstruction of an anterolateral thigh flap in a patient with a diagnosis of squamous cell carcinoma of the hard palate, who had undergone reconstruction after surgical resection. A, CT scan before contouring. Contouring shown on B, axial CT image; C, coronal CT image; and D, sagittal CT image. E, CT scan showing 3-dimensional reconstruction; and F, automatic calculation of the flap volume.
Figure 1
Computed tomography (CT) images showing contouring and 3-dimensional reconstruction of an anterolateral thigh flap in a patient with a diagnosis of squamous cell carcinoma of the hard palate, who had undergone reconstruction after surgical resection.
A, CT scan before contouring. Contouring shown on
B, axial CT image;
C, coronal CT image; and
D, sagittal CT image.
E, CT scan showing 3-dimensional reconstruction; and
F, automatic calculation of the flap volume.

Study Variables

The clinical factors that might be associated with the postoperative volume change of the ALTFs were examined as possible predictors. These included 1) demographic factors (ie, age, gender); 2) factors associated with the patient's general condition and personal history (ie, diabetes mellitus [DM], hypertension, body mass index [BMI], smoking status, alcohol consumption); and 3) treatment factors (ie, primary sites, history of surgery in the oral and maxillofacial region, postoperative radiotherapy, postoperative chemotherapy).

We measured the volume of the ALTFs at 1, 3, 6, 12, and 24 months postoperatively. The flap volume at 1 month postoperatively was set as the baseline. We defined the postoperative residual rate as the ratio between the present volume of the ALTF at each month and the baseline volume. The primary outcome variables were the postoperative residual rates at 3, 6, 12, and 24 months.


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