Autologous reconstruction with the lumbar artery perforator (LAP) free flap

Introduction

The ideal breast reconstruction gives the patient a durable result that is aesthetically pleasing while causing minimal donor site morbidity. The deep inferior epigastric artery perforator (DIEAP) flap is the gold standard, but when a DIEAP flap is not possible we should be able to provide an alternative to those patients seeking an autologous breast reconstruction. Several other perforator flaps have been suggested but few have sufficient volume, shape or feel of native breast tissue in combination with limited donor site morbidity and acceptable scarring.

The lumbar artery perforator (LAP) flap anatomy

Lumbar arteries are somatic segmental branches of the abdominal aorta and correspond to the posterior intercostal arteries of the thoracic aorta. There are four levels (L1–L4) but only the lower two (L3 and L4) are of interest to the reconstructive surgeon. The arteries on the right pass posterior to the inferior vena cava. The blood vessels pass behind the psoas major muscle, run past the transverse process of the vertebrae and cross the quadratus lumborum, with the upper three arteries running posteriorly and the fourth anterior to it. They then pierce the posterior aponeurosis of the transversus abdominis muscle, and travel anteriorly between it and the internal oblique. Sometimes an intramuscular course through the erector spinae is encountered. The pedicle then pierces the thoracolumbar fascia or is sometimes encased by it for up to 1.5 cm ( Figs. 37.1–37.3 ). It then enters the subcutaneous fat of the “love handles” and branches out from medial to lateral to perfuse the skin surface overlying the iliac crest. This skin island is innervated by the superior cluneal nerves, that also emerge from beneath the thoracolumbar fascia. These cluneal nerves can be incorporated in the flap for a sensate reconstruction (see Fig. 37.3 ).

The mean diameter of the lumbar artery and vein ranges from 2.1 mm to 2.8 ± 0.3 mm. The size of the skin island that can be harvested is determined by a skin pinch. The amount of redundant skin at the flank is considerably less than the average abdominal excess.

Interposition graft

The LAP flap pedicle can be harvested up to 7 cm, but deep dissection toward the transverse process of the lumbar vertebra is tedious and may cause nerve damage leading to local pain syndromes or disabling neuropraxia. There usually is a caliber mismatch between the internal mammary vessels and the lumbar vessels. This is the main reason to always harvest an arterial and venous interposition graft ( Fig. 37.4 ). The preferred incision is along Langer’s lines, low on the abdomen ( Fig. 37.5 ). The internal epigastric vessels are the best match, if they are still available. As an alternative the thoracodorsal bundle or the descending branch of the lateral circumflex femoral artery and vein can be harvested. Anastomosis of the interposition graft to the flap pedicle is performed with a nylon 10-0 on a separate back table, while the second team closes the donor site and turns the patient.

Historical perspective

Kroll and Rosenfeld introduced flaps based on paraspinous and parasacral perforators in 1988. These perforator-based flaps were performed to reconstruct defects of the midline of the back and lumbosacral area. In 1980, Bostwick et al . described the “reverse” latissimus dorsi muscle musculocutaneous flap based on the lower intercostal and lumbar artery perforators (LAPs). In 1999 Kato et al . described a pedicle LAP flap in an anatomic and clinical study. Offman et al . analyzed the lumbar arteries in an anatomic study with angiograms and fresh cadaveric dissections. Lui et al . described the 3D anatomy of the LAP flap. Kiil et al . investigated LAPs in a cadaveric and clinical anatomic study, performing CT angiography preoperatively as a virtual dissection tool.

Musculocutaneous and adipofascial flaps from the lumbar region were mainly used as pedicled flaps for the reconstruction of sacral pressure sores and low lumbar defects. The first application of a lumbar flap as a free flap for breast reconstruction was reported in 2003 by de Weerd et al . The first case series of 100 flaps was published in 2018 and papers comparing the lumbar flap tot the DIEAP flap or investigating the patient reported outcomes of the LAP flap demonstrate its value in autologous breast reconstruction. Over the years the technique has been improved, the operative sequence and timing is optimized and the lumbar artery perforator flap is slowly gaining popularity. Bilateral reconstructions are usually staged but immediate bilateral reconstructions have been reported and are deemed feasible in expert centres.