Latissimus Dorsi Flap

Flap
Tissue	Muscle or musculocutaneous flap, pedicle or free
Course of the vessels	From the axilla along the anterior border of the muscle: it enters the muscle from underneath and then spreads into the three major branches at the undersurface of the muscle
Dimensions	Can be tailored to almost any size; maximum dimensions, 20 × 35 cm
Extensions and combinations	Can be raised as muscle, musculocutaneous, and perforator flap; combinations are possible with any component from the subscapular system (i.e., bone, skin, fascia, or muscle)
Anatomy
Neurovascular pedicle	Thoracodorsal artery
Artery	Usually one vein that originates from the subscapular vein
Veins	Up to 15 cm; branches of the subscapular system; anatomical variations in 3–5% of population
Length and arc of rotation	Artery, 2–4 mm; vein, 2–5 mm
DiameterNerve	Motor nerve; some studies report deep sensation 18 months after coaptation to the sensory recipient
Surgical technique
Preoperative examination and markings	No vessel identification necessary; in cases of previous axilla dissection or radiation, check muscle function; if muscle function is intact, vessels are usually not violated; mark the anterior muscle border and the tip of the scapula to outline the flap borders
Patient position	Midlateral; arm elevated 90 degrees
Dissection	Mark the flap dimensions; start with an incision along the muscle border; identify the muscle border and branch to the serratus muscle; identify the pedicle and follow the pedicle to its origin; free the anterior border of the muscle and raise the flap from ventral to dorsal toward the spine; take care to coagulate or ligate the perforating vessels; divide the muscle distally as required; divide the muscle at the spine insertions; raise the muscle in a cranial direction; ligate the serratus branches; check perfusion; divide the pedicle
Advantages
Vascular pedicle	Long and reliable; large-caliber vessels
Flap size and shape	Any flap size is possible: the latissimus dorsi is the largest muscle in the body
Combinations	Numerous combinations are possible, including multicomponent flaps with other flaps from the subscapular system; vascularized bone can be harvested as rib grafts with the latissimus dorsi or on a connected pedicle from the scapula; fascia can be added from the serratus muscle
Further options	Scapular flaps are still available if the latissimus dorsi is harvested correctly; the serratus muscle is available, but vessels are small
Disadvantages
Bulkiness	Muscle can be bulky; skin islands in musculocutaneous flaps are usually bulky and require secondary contour correction
Donor site morbidity	Donor scar is rather conspicuous; approximately 7% loss of shoulder function
Pearls and pitfalls
Dissection	Watch out for constant large perforator vessels at the tip of the scapula (ligate); finalize the dissection of the pedicle by splitting the fascial leaf, which separates the latissimus dorsi from the teres muscles dorsally; ligate the branch to the scapula, and do not confuse it with the second branch to the muscle; take a skin island as a monitoring island, if desired.
Extensions and combinations	Dissect the pedicle up to the axillary artery to rule out anomalies of the vascular system so that all components are nourished by one pedicle; if there are anomalies, the operative strategy has to be adjusted to perform additional microanastomoses
Contouring and correction	Muscle flaps usually shrink, and contouring is required in approximately 50% of cases; musculocutaneous flaps almost all tend to sag and need contouring; in the case of functional muscle transfers, readjusting muscle tension is sometimes required
Clinical applications	Coverage of large surface area defects; functional free muscle transfer for loss of forearm flexor and extensor systems; pedicle muscle transfer for restoration of biceps function