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PURPOSE:Although the anterolateral thigh (ALT) flap can be raised in most cases, occasionally the perforators are inadequate or absent necessitating the exploration of the contralateral thigh or a whole new flap. If anteromedial thigh (AMT) perforators were useable in these instances, harvest could proceed from a single donor site. The vascular anatomy of the anteromedial thigh (AMT) flap has, however, not been well defined. The purpose of this study was to determine the perforator patterns and vascular anatomy of the AMT flap and the usefulness of this flap when the ALT flap is unfavorable.
METHODS:A prospective cohort study was performed examining 100 consecutive thighs. ALT and AMT skin territories were surgically explored, and perforator size, number, and the source vessels were documented. The relationship between ALT and AMT perforator size and number was examined using Fisher’s Exact test, logistic regression and linear regression.
RESULTS:Twenty-one of the 100 thighs had no AMT perforators. For the remaining thighs, there were two sources of perforators: the rectus femoris branch (RFB) of the descending branch of the lateral circumflex femoris artery, and the superficial femoral artery. Perforators from the latter were short and small, and thus less useful. AMT flaps based on RFB perforators shared the same vascular pedicle as the ALT flap in all cases, and were thus clinically useful. Therefore, only perforators from the RFB were considered true AMT perforators. These perforators, however, were present in only 51% of the patients. Their surface locations follow a similar pattern as the ALT flap with the majority of perforators near the midpoint, but an average of 3.2 cm medial to line connecting the anterior superior iliac spine and the supralateral patella. Forty-three thighs had a single RFB perforator and 8 had 2 perforators. Sixty-six percent were septocutaneous while the rest traversed a thin layer of the rectus femoris muscle. Patients with small or no ALT perforators usually had a large AMT perforator. Patients with large or medium ALT perforators usually had medium or small AMT perforators (p=0.029). Patients with small or no ALT perforators had a 6-fold increased chance of large/medium AMT perforators (OR=6.18, 95%CI=1.23-30.91, p=0.026). Patients without ALT perforators usually had one or more AMT perforators. Patients with three ALT perforators usually had no AMT perforators (p<0.001). Patients with one or fewer ALT perforators had a 4-fold increased chance of an AMT perforator (OR=3.77, 95%CI=1.34-10.65, p=0.012). After assigning numeric values to perforators based on size, the total scores for ALT and AMT regions were analyzed using a linear regression model. Lower ALT perforator scores were significantly related to higher AMT scores (slope=-0.33, 95% CI= (-0.46, -0.20), p<0.001). The Spearman’s test showed a similar relationship (ρ=-0.43, p<0.001).
CONCLUSION:The perforator patterns of the AMT flap were examined and defined. There is an inverse relationship between size and number of ALT and AMT perforators: when ALT perforators are inadequate, AMT perforators are typically useable.