Scapular and Parascapular Free Tissue Transfer Treatment & Management

Several patient-related factors should be taken into account when considering a patient for microvascular free tissue transfer. Existing comorbidities, such as severe cardiovascular disease, diabetes mellitus, coagulopathies, polycythemia, and sickle cell disease, may pose significant challenges to the reconstructive efforts, and alternative reconstructive options should be equally considered.

Patients who are obese also present unique reconstructive challenges. The amount of subcutaneous fat present may pose problems for particular locations such as the floor of the mouth or external defects. Harvesting fascia rather than full-thickness soft tissue in these patients may be necessary in order to minimize bulk.^{[17, 18]} In addition, positioning these patients for flap harvest may also prove extremely difficult and prevent the use of this donor site.

Positioning the patient is critical to the harvest of this flap. The patient needs to be positioned in the lateral decubitus position. Harvesting from the nondominant arm is preferable to reduce postoperative morbidity, although the flap is usually harvested from the same side as the neck dissection. A vacuum beanbag is required to maintain patient position during the harvest. An axillary roll is required to reduce traction on the opposite brachial plexus. The back and arm of the donor site should be prepared at the same time as the extirpative site. Simultaneous extirpation and harvest is tenuous at best and usually cannot be achieved.

The harvest is begun by first identifying the muscular triangular space, as previously described. This can be done by palpation; however, a Doppler probe can be used to localize the circumflex scapular artery (CSA) as it enters the triangular space, thus confirming its location. An assistant is needed to hold the arm, keeping the humerus abducted and the teres major and minor under some tension.

Elliptical cutaneous skin paddles can be designed to suit the needs of the defect. The parascapular flap is taken along the axis of the lateral border of the scapula corresponding with the descending branch of the circumflex scapular artery (CSA). The scapular flap is designed along the horizontal plane almost perpendicular to the lateral border of the scapular bone and corresponds to the transverse branch of the circumflex scapular artery (CSA). A portion of the cutaneous portion of the flap must overlie the triangular space to ensure capturing the circumflex scapular artery (CSA) and its branches.

The superior limit of the harvest is the scapular spine; the inferior limit is the tip of the scapula. Care must be taken when traversing the midline in an attempt to harvest additional skin because this portion is less reliable. The width of the skin paddles and the amount of tissue harvested should obviously suit the needs of the defect. Flap elevation proceeds from medial to lateral in a plane just superficial to the fascia of the infraspinatus, rhomboid, and trapezius muscles. Dissection can also be carried out in the subfascial plane. However, identifying the superior border of the teres major muscle and following it toward the triangular space to avoid injuring the circumflex scapular artery (CSA) and its branches is important.

If scapular bone is to be harvested, the circumflex scapular artery (CSA) is first identified and the teres major muscle divided. This provides the exposure necessary to identify the lateral border of the scapula, the TDA, and possibly the angular artery, which may need to be preserved if the scapular tip is to be harvested in continuity or used as a separate segment of bone.

The muscular branches of the circumflex scapular artery (CSA) must be taken during this part of the harvest. The periosteal branches are taken if a fasciocutaneous flap is to be harvested. With the vascular pedicle identified, the bone can be harvested. An incision is made parallel to the lateral border of the scapular bone through the teres major, teres minor, and infraspinatus muscle. Osteotomies can now be performed using a reciprocating or sagittal saw. Take care to stay at least 1 cm below the glenoid fossa to preserve joint integrity. At this point, the attachments of the subscapularis muscles can be severed to mobilize the bone segment. The vascular pedicle is then traced to its takeoff from the axillary artery.

Primary closure of the donor site can usually be achieved and may require a significant amount of undermining. Use of a split-thickness skin graft in this dependent area is less desirable and should be avoided. The teres major muscle should be approximated to the cut end of the infraspinatus muscle or the cut end of the scapular bone via drill holes. Take care to achieve meticulous hemostasis to avoid postoperative hematoma. Large-bore suction drains should be used for several days postoperatively to minimize hematoma and seroma formation.

Osteotomies can be made in order to contour the bone flap to the reconstruction plate. Take care to preserve overlying periosteum and muscle at the osteotomy site by creating subperiosteal tunnels with a freer prior to making osteotomies. The bone flap can then be secured to the reconstruction plate with the appropriate monocortical screws. Skin flaps can then be inset according to the needs of the defect. Microvascular anastomosis can be performed before or after insetting the flap, based on the surgeon's preference and experience.

In cases in which skin is needed for intraoral and external lining, draping the cutaneous portion of the flap over the bone flap may be necessary. Take care to avoid excess tension on the skin flap as it courses over the bone because venous outflow problems for the external component of the flap can result. This can be avoided by harvesting skin flaps of appropriate size and length for the defect.

Postoperatively, the donor arm should be immobilized in an arm sling for about 5 days. Physical therapy can then be instituted to improve passive and active range of motion. Intensive home physical therapy to improve shoulder strength can begin within 3 weeks after surgery. This greatly limits postoperative morbidity.

Postoperative monitoring of flap vascular flow with serial examination, external Doppler, pinprick, or an implantable Doppler device is at the discretion of the reconstructive surgeon. Use of anticlotting agents such as heparin, aspirin, and dextran are also used at the judgment of the surgeon and are not detailed here.

A number of potential complications are associated with the use of the scapular/parascapular donor site. Early complications include hematoma formation, which can result from inadequate hemostasis or coagulopathy. Seroma formation can develop given the amount of dead space present after harvest. Maintaining large suction drains for several days postoperatively helps to alleviate this problem. Wound dehiscence and skin breakdown at the donor site can also develop. This is particularly problematic with large defects that are closed under tension.

Significant undermining of adjacent tissue may be required to obtain primary closure. Skin grafting in this dependent mobile area should be avoided. Wound infection is a rare complication. Use separate instruments and clean gloves and gowns at the donor site to avoid contamination and subsequent wound infection. The donor site is closed prior to working on the recipient site. Antibiotic prophylaxis should be used.

Take care to avoid injury to the long thoracic nerve, which supplies the serratus anterior, because this can result in a winged scapula. Injury to the brachial plexus has been reported with the harvest of the latissimus flap secondary to arm positioning during harvest.^{[19, 20]} Similar injuries can be observed with scapular flap harvest because patient positioning is similar. Take care to avoid extreme elevation of the arm, and support for the head should be provided during harvest.

Few studies have looked at donor site morbidity related to the harvest of the scapular flap. In a 1989 report, Sullivan et al evaluated range of motion and shoulder strength in 12 patients who underwent scapular osteocutaneous free tissue transfer.^[21] In the initial postoperative period, shoulder strength and range of motion were significantly affected. Most patients had return of arm flexion and abduction, and all were subjectively satisfied with their level of function. In 2000, Coleman et al addressed donor site morbidity in 5 patients who underwent objective testing, as well as evaluation by questionnaire.^[22] This group showed only minor limitations in strength and range of motion.

The scapular/parascapular donor site is unsurpassed in the variability of tissue available for reconstructing complex defects of the head and neck, particularly through-and-through oromandibular and large palatomaxillary defects. Bone, skin, fascia, and muscle are available to the reconstructive surgeon. The ease of harvest, reliability, and limited morbidity associated with the use of this flap make it a desirable donor site in select patients. The disadvantages are few, including the need for repositioning the patient, lack of sensation in the flap, and limited bone stock for osseointegration, particularly in females. Every reconstructive surgeon should be familiar with this important donor site for head and neck reconstruction.