The Gracilis Myocutaneous Free Flap: A Quantitative Analysis of the Fasciocutaneous Blood Supply and Implications for Autologous Breast Reconstruction

BACKGROUND: Mastectomies are one of the most common surgical procedures in women of the developed world. The gracilis myocutaneous flap is favoured by many reconstructive surgeons due to the donor site profile and speed of dissection. The distal component of the longitudinal skin paddle of the gracilis myocutaneous flap is unreliable. This study quantifies the fasciocutaneous vascular territories of the gracilis flap and offers the potential to reconstruct breasts of all sizes. METHODS: Twenty-seven human cadaver dissections were performed and injected using lead oxide into the gracilis vascular pedicles, followed by radiographic studies to identify the muscular and fasciocutaneous perforator patterns. The vascular territories and choke zones were characterized quantitatively using the 'Lymphatic Vessel Analysis Protocol' (LVAP) plug-in for Image J® software. RESULTS: We found a step-wise decrease in the average vessel density from the upper to middle and lower thirds of both the gracilis muscle and the overlying skin paddle with a significantly higher average vessel density in the skin compared to the muscle. The average vessel width was greater in the muscle. Distal to the main pedicle, there were either one (7/27 cases), two (14/27 cases) or three (6/27 cases) minor pedicles. The gracilis angiosome was T-shaped and the maximum cutaneous vascular territory for the main and first minor pedicle was 35 × 19 cm and 34 × 10 cm, respectively. CONCLUSION: Our findings support the concept that small volume breast reconstructions can be performed on suitable patients, based on septocutaneous perforators from the minor pedicle without the need to harvest any muscle, further reducing donor site morbidity. For large reconstructions, if a 'T' or tri-lobed flap with an extended vertical component is needed, it is important to establish if three territories are present. Flap reliability and size may be optimized following computed tomographic angiography and surgical delay

(A) A ‘screen grab’ image demonstrating the process of quantifying a radiographic injection study of the gracilis muscle and overlying fasciocutaneous tissues.

<p>Image was opened in Image J<b>®</b> and ‘initialized’ in the LVAP ‘Lymphatic Vessel Analysis Protocol’ (LVAP) plug-in. The image was then overlayed with two grids (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036367#s2" target="_blank">methods</a>) to allow systematic quantification of vessel density. Each yellow dot represents a counting point. (B) Graphical representation of the quantified average vessel density in both the muscle and skin specimens, in each one third of the flap.</p

(A) A ‘screen grab’ image of a radiographic injection study of the gracilis muscle and overlying fasciocutaneous tissue demonstrating the relative perfusion for each one third of the tissues.

<p>Image opened in Image J<b>®</b> and ‘initialized’ in the LVAP ‘Lymphatic Vessel Analysis Protocol’ (LVAP) plug-in. (B) Graphical representation of the relative perfusion for each one third of the tissues of the gracilis muscle and overlying fasciocutaneous tissues.</p

Modifications of gracilis flap design in order to increase flap volume.

<p>Modifications of gracilis flap design in order to increase flap volume.</p

A summary of the anatomical characteristics of the gracilis perforator vessels.

<p>A summary of the anatomical characteristics of the gracilis perforator vessels.</p

A volume rendered (VR) reformat of a computed tomographic angiogram showing musculo-cutaneous perforators traversing the gracilis muscle to supply the overlying skin.

<p>(Reproduced with permission from: Rozen WM, Chubb D, Grinsell D, Ashton MW. <i>Computed tomographic angiography: clinical applications</i>. Clin Plast Surg. 2011 Apr; 38(2): 229–39.).</p

Blood supply to the gracilis flap clarifying the nomenclature to be used in this article, and showing the dominant and minor pedicles.

<p>(Adapted from Strauch B, Han-Liang Yu. (2006) <i>Atlas of Microvascular Surgery</i>, 2^nd Edition, Thieme).</p

A summary of the anatomical characteristics of the gracilis vascular pedicles.

<p>PF (profunda femoris), MCFA (medial circumflex femoral artery), SFA (superficial femoral artery), PA (popliteal artery), OA (obturator artery), AB (ascending branch of main pedicle).</p

A cadaveric angiogram showing the gracilis cutaneous ‘two territory’ flap taking the shape of a “T”, positioned posteriorly.

<p>A cadaveric angiogram showing the gracilis cutaneous ‘two territory’ flap taking the shape of a “T”, positioned posteriorly.</p

A computed tomographic angiogram (CTA) of the lower limbs, with coronal maximum intensity projection (MIP) reformat, highlighting the gracilis muscle and its major and minor arterial muscular pedicles.

<p>On the left, one major (green) and one minor (purple) pedicle can be seen and on the right, one major (green) and two minor (purple) pedicles. (Right thigh ‘3 territory’ flap and left ‘two territory’ flap).</p