Use of the Trapezius Myocutaenous Flap for Shoulder Reconstruction

© 2024 HMP Global. All Rights Reserved.

Any views and opinions expressed are those of the author(s) and/or participants and do not necessarily reflect the views, policy, or position of ePlasty or HMP Global, their employees, and affiliates.

A 68-year-old male presented with a right upper back lesion. Biopsy confirmed high-grade pleomorphic sarcoma. Following completion of neoadjuvant radiation therapy (Figure 1), the mass was removed with 1 to 2 cm of normal surrounding tissue. This required resection of the rhomboid major, portions of the infraspinatus, and teres major muscles. The resection defect measured approximately 12 × 12 × 8 cm (Figure 2). A trapezius myocutaneous flap was used to reconstruct the defect (Figure 3A). The muscle was divided along its medial border, then raised in a caudal-to-cranial direction (Figure 3B). Dissection continued superiorly until enough rotation was available to allow inset without undue tension (Figure 3C). At the end of elevation, a drain was placed and brought out through the right lateral chest. The flap was rotated into place and inset. Patient was monitored postoperatively with flap checks every 4 hours and instructions for no ice, heat, pressure to the flap, or abduction of the arm above 90 degrees. Inpatient stay was unremarkable. He followed up in clinic at postoperative weeks 1, 2, 4, 10 (Figure 4, A-D), and 16. His flap healed without complications, resulting in full range of motion of the shoulder with no instability.

Figure 1. Preoperative right upper-back lesion status post neoadjuvant radiation.

Figure 2. Resection defect measured approximately 12 x 12 x 8 cm, with exposed scapula. 

Figure 3. Intraoperative view of trapezius myocutaneous flap reconstruction. (A) Flap outline. (B) Flap harvest. (C) Flap transposition, showing planned primary closure at harvest site. 

Figure 4. (A) 2 weeks, (B) 4 weeks, (C, D) 10 weeks postoperative.

The goals of posterior shoulder reconstruction include coverage of critical structures (vessels, bone), filling dead space, and maintaining function (ie, shoulder rotation). Common reconstruction options include the trapezius myocutaneous flap, latissimus dorsi myocutaneous flap, parascapular/scapular flap, and wide-based random pattern flaps if adequate soft tissue is available. These flaps are local options that, when rotated into a posterior shoulder defect, provide adequate muscle and/or soft tissue for coverage of exposed scapula or spine without compromising neck and shoulder movement.^1,2

The trapezius is a large superficial muscle of the back consisting of descending, transverse, and ascending fibers that attach to distinct landmarks. The descending fibers attach to the external protuberance of the occipital bone and spinous process of C7 vertebra; the transverse fibers originate from the spinous processes of vertebrae T1-T5, and the ascending fibers connect with spinous processes of T6-T12 vertebrae.^{3, 4} The variation in muscle fiber orientation allows the physician to identify landmarks and blood supply when harvesting the flap. According to several studies, the trapezius myocutaneous flap has a maximum length of 38 cm and maximum width of 7 to 22 cm.⁵ This provides adequate coverage of defects that are extensive in size. In addition to the considerable size, the trapezius muscle is pliable and thinner compared with other available flaps such as the latissimus dorsi or pectoralis major flap. These characteristics allow primary closure of the donor site and a wide arc of rotation of the flap.⁶ The trapezius muscle flap has a Mathes and Nahai type II vascular arrangement. This corresponds to having a dominant vascular pedicle, with the occipital artery, transverse cervical artery (TCA), or dorsal scapular artery, depending on the portion of flap, and minor vascular pedicle, with the posterior intercostal arteries.⁵ The superior portion of the muscle is supplied by branches of the occipital artery. The middle portion is supplied by the superficial cervical artery (SCA), which originates from the superficial portion of the TCA. The lower portion of the muscle is supplied by the dorsal scapular artery (DSA), which originates from the deep portion of the TCA.^7,8 Understanding the variation in blood supply allows tailoring of the flap to include more portions of its blood supply to support healing.

To harvest the trapezius myocutaneous flap, the patient is placed in prone position. Useful landmarks for the trapezius muscle include the occipital protuberance, midline, an oblique line from the acromion to the T12 spinous process, and the tip of the scapula. The triangular muscle sits medial to the tip of the scapula.⁹ The skin paddle is drawn out to cover the defect while still allowing primary closure of the donor site. It is oriented to allow adequate rotation into the defect without tension or kinking, and is no longer than 10 cm from the tip of the scapula to ensure adequate perforators. The muscle is harvested with the overlying skin paddle. Dissection begins in a caudal-to-cranial direction until the desired pedicle is visible. The pedicle is then dissected out to create an islandized flap to allow for easier rotation. Preservation of a good portion of trapezius muscle decreases the risk of donor site morbidity. The donor site is closed primarily with drains to prevent seroma formation.⁹

The trapezius myocutaneous flap is technically challenging given the variability in anatomy. Damage to the dorsal scapular nerve or spinal accessory nerve during dissection of the muscle is a known complication that can arise during flap harvest.^7,10 A disrupted dorsal scapular nerve will present as a winged ipsilateral scapula sign on physical exam. An impaired spinal accessory nerve may present as neck pain/weakness when turning the head in the contralateral direction, asymmetrical shoulders, or the inability to shrug the ipsilateral shoulder.¹¹ Additionally, there is risk of compromising arterial supply to the tip of the flap if it is marked out too distal to the known pedicles. It is important to monitor the perfusion of the myocutaneous flap intra- and postoperatively as a hypoperfused flap can result in ischemic tissue, leading to partial/total flap loss and/or infection.^12,13 Indocyanine green can be used intraoperatively to assess flap perfusion.¹⁴