Latissimus dorsi flap

A DETAILED DESCRIPTION OF THE LATISSIMUS DORSI MUSCLE FLAP FOR RECONSTRUCTION FOR PLASTIC SURGERY RESIDENTS

1. LATISSIMUS DORSI FLAP DR G SWAMY VIVEK SENIOR RESIDENT DEPT OF PLASTIC SURGERY GMCH , GUWAHATI

2. HISTORY The latissimus dorsi flap was introduced by Tansini in 1906 for the coverage of extensive mastectomy defects.

3. FLAP ANATOMY The latissimus dorsi muscle is the mirror image of the pectoralis major muscle

4. ORIGIN AND INSERTION ORIGIN: Spinous process of vertebrae T7-L5, Thoracolumbar fascia, Iliac crest, Inferior 3-4 ribs, Inferior angle of scapula. INSERTION: Floor of intertubercular groove of the humerus.

5. The superior portion of the medial aspect of the latissimus muscle is covered by the trapezius muscle; otherwise, the latissimus muscle is superficial to all other muscles in the back. The latissimus muscle covers a portion of the paraspinal muscle and the majority of the serratus anterior muscle. In the middle portion there is a rather tight attachment to the 10th, 11th, and 12th ribs and to the fibers that interdigitate with fibers of the serratus anterior muscles. Superiorly it is adherent to the inferior border of the teres major muscle.

6. it spirals 180° around and travels anterior to the tendon of the teres major muscle before insertion into humerus.

7. FUNCTIONS There are numerous important functions of the latissimus dorsi muscle. Primarily it acts as an extender, adductor, and medial rotator of the humerus. It holds the inferior angle of the scapula against the chest wall and stabilizes and elevates the pelvis when bringing the lower extremity forward. It aids in coughing and it pulls the arm posteriorly, directly behind the back, a motion that is best described by the terminal action of pushing off with a ski pole

8. ARTERIAL SUPPLY OF FLAP The latissimus dorsi muscle has a dual blood supply from the subscapular artery and the posterior paraspinous perforators. Both circulatory systems are diffusely interconnected so that the muscle can survive in its entirety if either pedicle is interrupted.

9. Dominant:  thoracodorsal artery, a branch of the subscapular artery Length: 8.5 cm (range 6.5–12 cm) Diameter: 3 mm (range 2–4 mm) The thoracodorsal artery courses from the axilla along the anterior border of the latissimus dorsi muscle, enters the muscle from underneath, and spreads into two or three major branches at the undersurface of the muscle.

10. The neurovascular hilus was found on the deep surface of the latissimus dorsi muscle approximately 4 cm distal to the inferior scapular border and 2.5 cm lateral to the medial border of the latissimus muscle. At that point there was a constant bifurcation into a horizontal (medial or transverse) branch and a descending (lateral or vertical) branch, but there are interconnections between the horizontal and descending/lateral branches.

11. Within the muscle, both branches divide into lesser branches, which run medially and anastomose with perforators from intercostals and lumbar arteries. Both branching patterns supply the muscle with long, parallel neurovascular branches, which run in the fascia between bundles of muscle fibers and thereby enable the muscle to be split into independent vascularized innervated units.

12. All thoracodorsal cutaneous perforators originated within a distance of 8 cm distal to the neurovascular hilus. The thoracodorsal artery supplies predominantly the latissimus dorsi muscle but also gives branches to the serratus anterior muscle, the axillary skin, and the subscapular and teres major muscles. The subscapular artery arises in general, as a branch of the third portion of the axillary artery. Usually the circumflex scapular artery is found to be the first branch of the subscapular artery. The second major branch of the subscapular artery is the thoracodorsal artery.

13. Minor:  perforating posterior branches of the posterior intercostal arteries. These vessels predominantly supply the distal part of the latissimus dorsi muscle. They are found in two rows as segmental vessels 5–10 cm from the dorsal midline. There are usually 4–5 vessels in each segmental row. The lateral row derives its blood supply from branches of the posterior intercostal artery and the medial row derives its blood supply from the lumbar artery.

14. VENOUS DRIANAGE OF THE FLAP Accompanying veins follow the arteries Primary:  thoracodorsal vein Length: 9 cm (range 7.5–10 cm) Diameter: 3.5 mm (range 2–5 mm) Usually, the thoracodorsal vein originates from the subscapular vein

15. Secondary:  concomitant veins, running with the perforating arterial vessels, provide secondary venous drainage Length: 2 cm (range 1.5–2.5 cm) Diameter: 2 mm (range 1.1–2.7 mm) The lower and medial parts of the muscle preferentially drain through the intercostals and lumbar venous system and not via the thoracodorsal system. the circumflex scapular vein can provide secondary drainage of the flap.

16. FLAP INNERVATION Sensory:  the posterior branches of the lateral cutaneous branches of the intercostal nerves provide cutaneous sensibility laterally, and lateral branches of the posterior rami (VI through XII) posteriorly Usually these branches are not used to reinnervate the flap, but in the special case when a reverse pedicled flap is performed based on the posterior intercostal vessels, its sensory innervation can be preserved and so the sensory innervation can be maintained.

17. Motor:  the thoracodorsal nerve arises from the posterior cord of the brachial plexus and travels latero-inferiorly behind the axillary artery and vein Even if only a small portion of muscle is included, the entire muscle is denervated. The nerve divides into lateral and medial branches approximately 1.3 cm proximal to the neurovascular hilus and each branch runs with its vascular counterpart

18. if the intention is to split the muscle and retain half of it on the chest with an intact nerve supply, then the dissection is more complicated.

19. FLAP COMPONENTS The latissimus dorsi flap can be raised as a muscle, or a musculocutaneous, an osteomusculocutaneous , or even a perforator flap (TDAP). Combinations and extensions are possible with any component from the subscapular system (i.e., bone, skin, fascia, muscle). On the same pedicle, it can be elevated with the serratus fascia or the serratus muscle, the accompanying rib or part of the scapula, or with a scapular or parascapular flap. In this way it is possible to harvest multicomponent flaps to simultaneously reconstruct complex defects with several flaps based on a single pedicle

20. ADVANTAGES Latissimus dorsi dissection is rapid, easy, and safe because of the reliable anatomy of the thoracodorsal and subscapular vessels. Microvascular transfer is facilitated by the long pedicle and large caliber of the vessels. A skin island can be orientated vertically, obliquely, or transversely as desired or required by the defect. It can be tailored to almost any size and shape. The flap can extend from the axilla to almost the iliac crest. As a pedicled flap, it is certainly one of the most versatile flaps for reconstructive problems of the chest wall and the upper arm. The pedicled muscle flap alone will also supply coverage for massive defects of the head and neck area as well as the shoulder.

21. The musculocutaneous latissimus flap may be advantageous in providing bulk for the correction of contour defects. Combined (“chimeric”) flaps with other components from the subscapular system can be designed, vascularized bone can be harvested as rib grafts with the latissimus, or on a common pedicle from the scapula, fascia can be added from the serratus muscle. The thoracodorsal nerve can be included so that the muscle can be reinnervated for restoration of motor function.

22. DISADVANTAGES This flap, especially the musculocutaneous type, is generally bulky, depending on the general physical constitution of the patient. Even though the muscle atrophies to some degree, skin islands in musculocutaneous flaps are usually also bulky and require secondary thinning and contour correction for satisfactory aesthetic results. If all the other muscles of the shoulder girdle are intact, the loss of the latissimus dorsi muscular function is rarely noticeable in normal activities.

23. Occasionally, the harvest of this muscle will result in some winging of the scapula, even though the serratus anterior muscle is intact. It can also compromise the motion of “posterior push,” an important function in skiing, where the hand is pulling the body weight forward. Loss of the latissimus in paraplegics may also seriously weaken upper extremity function such as crutch-walking or bed-to-wheelchair transfer. Similarly, in patients with poliomyelitis or other neuromuscular diseases, loss of the latissimus dorsi muscle may seriously weaken pelvic stability Pains at the donor site and seroma formations are occasionally seen

24. PREOPERATIVE PREPARATION No preoperative vessel identification is necessary. In cases of previous axilla dissection or radiation, muscle function has to be evaluated preoperatively. If muscle function is intact, the vessels are likely not violated. If the muscle function does not seem to be good or if the suspicion is high for vessel injury, further studies such as tracing the vessel course with high resolution ultrasound may be performed to see if adequate perfusion is available. A donor site for possible skin grafting is also prepped and draped.

25. FLAP DESIGN ANATOMIC LANDMARKS

26. SPECIAL CONSIDERATIONS BREAST RECONSTRUCTION the island over the upper free muscle border should be designed in a way that closure of the secondary defect leaves a transverse scar that is easily concealed by a brassiere.

27. HEAD AND NECK RECONSTRUCTION if the flap is to be pedicled, a skin island along the anterolateral margin of the muscle is necessary because the transverse island will not reach.

28. SOFT TISSUE DEFECT OF THE LOWER EXTREMITY WITH A BONE DEFECT

29. FLAP DIMENSIONS Muscle Dimensions Length: 35 cm (range 21–42 cm) Width: 20 cm (range 14–26 cm) Thickness: 1.5 cm (range 0.5–4.5 cm) The average dimensions are 4–6 cm more in male patients than in female patients. Skin Island Dimensions Length: 18 cm (range up to 35 cm) Width: 7 cm (range up to 20 cm), maximum to close primarily : 8–9 cm Thickness: 2.5 cm (range 1–5 cm) The latissimus dorsi flap can be tailored to almost any size with a maximum dimension of 20×35 cm. Primary closure of the donor site can be achieved when the width is <8–9 cm.

30. Bone Dimensions Length: 5 cm (range 1.5–8 cm) Width: 2 cm (range 1–5 cm) Thickness: 2 cm (range 1–3 cm)

31. FLAP MARKINGS

32. PATIENT POSITIONING Most surgeons would agree that a lateral decubitus position is ideal for flap harvest, although it is possible with the patient in a prone or even a supine position with a 45° lateral tilt. The arm is abducted to 90°, the elbow also flexed 90°. More abduction may stretch the brachial plexus In cases of a free transfer to the lower extremity, the flap is usually harvested from the contralateral side

33. ANESTHETIC CONSIDERATIONS General anesthesia is needed to harvest the latissimus dorsi flap

34. TECHNIQUE OF FLAP HARVEST

35. DONOR SITE CLOSURE AND MANAGEMENT For standard flap designs, the donor site is closed as a direct closure after at least two drains are inserted. No special dressing is needed. Because of the high incidence of seroma formation, which occurs even with adequate suction, drainage of the donor site has constituted the biggest disadvantage of this flap. The donor site itself does not create any significant surface depression or excessive prominence of the ribs, but if more than 5 cm of skin is carried with the muscle, a widened scar can be expected. If a skin graft is required for the donor site, the resulting contour deformity can be remarkably unattractive, particularly in the obese patient

36. ARC OF ROTATION The latissimus dorsi, based on the major pedicle in the axilla, has a wide arc of rotation. Anterior arc: will cover the lateral abdomen (musculofascial flap), chest wall, and head and neck region. Posterior arc: will cover the lumbar, thoracic, and cervical vertebrae and will reach the posterior neck.

37. TYPICAL INDICATIONS FOR THE USE OF THIS FLAP AS PEDICLED FLAP BASED ON ANTERIOR ARC OF ROTATION Anterior and posterior chest wall defects Sternum osteitis Major coverage problems of the axilla, shoulder, and neck Less often for intraoral defects Massive defects of the temporal area Breast reconstruction Correction of surface coverage problems of the upper arm extending to the elbow

38. BASED ON POSTERIOR ARC OF ROTATION Proximally based obvious flap of choice for major upper back and scapular defects As a reversed flap for defects of the lower thoracic and lumbar areas Bilaterally, especially for soft tissue coverage in spina bifida patients

39. AS FREE FLAP HEAD AND NECK Major coverage problems. Coverage of intraoral defects, including mandibular reconstruction with a free rib.Functional muscle transfer for facial reanimation with the thoracodorsal nerve connected to the contralateral normal facial nerve in a one-stage procedure.

40. TRUNK Major coverage problems. UPPER EXTREMITY Major coverage problems. Free functional muscle transfer. LOWER EXTREMITY Major coverage problems. Treatment of chronic infections because of its excellent vascular supply.

41. ATYPICAL INDICATIONS FOR THE USE OF THIS FLAP PEDICLED TRANSFERS Pedicled innervated latissimus muscle transfer may be used for restoration of biceps or triceps function. FREE MICROVASCULAR TRANSFERS A free latissimus muscle or myocutaneous flap may be used for forearm flexion with or without finger flexion, or for forearm extension with or without finger extension.

42. POSTOPERATIVE CARE

43. GENERAL VASCULAR COMPLICATIONS Venous thrombosis Arterial thrombosis Vascular spasm

44. RECIPIENT SITE The suction drains are removed after 3–5 days, or when they accumulate <50 mL of fluid in 24 h. The skin clips or sutures are left for at least 14 days. Mesh grafts are dressed until the 5th day after the operation, and thereafter the dressings are changed every 2nd day. After 10 days, the wound can usually be left without dressing. Depending on the flap’s healing process, the patient’s stay in hospital will be about 2–3 weeks

45. DONOR SITE The suction drains are removed after 3–5 days, or when they accumulate <50 mL of fluid in 24 h. The skin clips or sutures are left for at least 14 days because of the tension. Mesh grafts are dressed until the 5th day after the operation, and thereafter the dressings changed every 2nd day. After 10 days, the wound can usually be left without dressings. If the donor site has been closed under tension, careful exercise of the affected shoulder can be started on the 3rd day, because limitation in movement quickly sets in owing to protective posturing, and not only in older patients.

46. UNTOWARD OUTCOMES Complications are those that are general and likely to be seen with any muscle flap. These include planning errors, technical intraoperative errors, and postoperative care errors, all of which can contribute to flap failure. The arc of rotation of the flap is limited by the location of the vascular pedicle and length of the flap. In thin patients, the flap will reach much farther. These factors have to be taken into account in preoperative planning. Furthermore, the orientation of the overlying skin on the muscle is less precise in obese patients

47. DONOR SITE The donor site itself does not create any significant surface depression or any excessive prominence of the ribs, but if >5 cm of the skin is carried with the muscle, a widened scar can be expected. If a skin graft is required for closure of the donor site, the resulting contour deformity can be remarkably unattractive, and it is difficult to achieve aesthetic closure of these donor sites, particularly in obese patients.Loss of function is not noticeable in normal individuals. In patients requiring the use of crutches, the effect is noticeable. Removal of the muscle can also affect pelvic stability in paraplegic patients. Winging of the scapula is also present in some patients

48. . To avoid this, care must be taken not to damage innervation to the serratus anterior muscle.The donor site constitutes the biggest disadvantage of this flap because of the high incidence of seroma formation, which occurs even with adequate suction drainage. These seromas are occasionally difficult to eradicate and can result in the formation of a bursa. If this happens, it is usually possible to collapse the cavity with a Penrose drain. After 4–6 weeks, this becomes an intractable problem, and it may be necessary to abrade or excise the two surfaces of the bursa to obtain healing.

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