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Scapula Flap

The Scapular Flap

Anatomic considerations

Tissue:
A skin and fat flap. It can be incorporated on the subscapular tree to make a chimeric flap. Flap sizes can be up to 10 by 25 centimeters. The lateral border of the scapula can be included to provide vascularized bone.
Innervation:
None.
Blood supply:
A transverse branch of the circumflex scapular artery.
Artery:
Large caliber if traced to the subscapular from 2 to 4 millimeters.
Vein(s):
Comparable in size to the artery.
Pedicle length:
Three to 7 centimeters can be obtained typically.

The scapular flap has become clinically popular because it provides a large area of fasciocutaneous tissue and is relatively straight forward to harvest.  It features consistent anatomy, a large pedicle and thick but pliable skin.  The fascial component of the flap - the dorsal thoracic fascia - can be harvested alone as a free fascial flap.  The donor defect can be closed primarily if the width does not exceed 10 centimeters.  If the defect cannot be closed it can be skin grafted, but this results in a significant scar deformity.

Anatomy

The anatomy of the scapular flap allows it to be harvested with a large number of other flaps on a single pedicle, allowing for complex and large reconstructions of composite tissue defects.  The scapular flap can be combined with any one of these tissues on the subscapular vessel axis:

The anatomy of the triangular space. The flap is supplied by a transverse branch of the circumflex scapular artery.

The above view is based posteriorly, exposing the muscles of the back.  The deltoid muscle has been removed for clarity.   The apex of the flap is centered over the triangular space, where the circumflex scapular artery provides the vessel to this flap after it travels through the triangular space.  The borders of the triangular space are made up of the

The trapezius and infraspinatus muscles are important landmarks since flap dissection proceeds from medial to lateral and these are identified early in the dissection.  The elevation of the flap is performed in the areolar fascial layer just above the thick muscular fascia of the back. The infraspinous fascia overlying the infraspinatus muscle and the teres minor fascia overlying the teres minor are particularly thick. If the flap is elevated deep to the this muscular fascia, the dissection can become confusing and especially difficult around the pedicle where the fascia surrounds the triangular space.

The circumflex scapular artery is a branch of the subscapular artery which takes origin off the axillary artery.  The circumflex scapular arises about 1 to 4 centimeters from the origin of the subscapular artery, but can on occasion arise directly from the axillary artery.  After the circumflex scapular artery pierces the triangular space it sprouts a transverse cutaneous scapular branch and a vertical parascapular branch.  The parascapular branch forms the basis of the parascapular flap.  The subscapular artery pedicle can be from 3 to 7 cm in length with vessel circumference at this level up to 4 millimeters in size.  Although the circumflex scapular artery is usually accompanied by two venae commitans, the subscapular artery is typically accompanied by one vein.

Flap Dissection

The patient is placed in the lateral decubitus position on a beanbag.   Optionally, the prone position can be used if a posterior wound must be resurfaced.  It can be more difficult since arm positioning can not be adjusted as easily as in the lateral decubitus position.  We will assume lateral decubitus positioning for further discussion.  The ipsilateral arm is left free and included in the operative scrub. A stockinette around the arm and Mayo stand with a well-padded pillow helps to rest the arm during surgery.

Marking the Flap

The flap is outlined with a lateral apex over the triangular space.

The incision is marked using the scapula as a guide.  The scapula is outlined and an elliptical incision is used to mark the flap.  It must include the triangular space within its border so the pedicle vessel is captured in the flap.  A point roughly one finger breadth below the mid point of the scapula on its lateral aspect marks the triangular space. A pencil Doppler probe can help confirm the pedicle location. The width of the flap can easily reach 10 centimeters with primary closure and has been reported to be as long as 25 centimeters. A point just crossing or touching the midline of the back is a safe distance.

Elevation of the Flap

The flap is elevated from medial to lateral superficial to the deep muscular fascia. Just before the pedicle pierces the fascia, the deep plane is entered.

Elevation of the Flap

Just at the triangular space the pedicle becomes visible as it pierces the deep fascia and enters the substance of the flap. The deep fascia is incised medial to this and around the pedicle, effectively "surrounding" it.

The flap is elevated from medial to lateral. The elevation of the flap is performed in the areolar fascial layer just above the thick muscular fascia of the back. The infraspinous fascia overlying the infraspinatus muscle and the teres minor fascia overlying the teres minor are particularly thick. If the flap is elevated deep to the this muscular fascia, the dissection can become confusing and especially difficult around the pedicle where the fascia surrounds the triangular space. In the inferior incision the descending arterial branch can be visualized and is ligated to continue flap elevation in a lateral direction. 

The flap is Elevated

The entire flap is isolated on the circumflex scapular system. To gain length, self retaining retractors are placed in the triangular space to follow the pedicle to the subscapular system.

As the triangular space is identified and the pedicle traced into the triangular space, self-retaining retractors and adjusting the right arm position to maximize exposure are helpful. Numerous branches must be isolated and ligated at this level before the flap is traced to the circumflex scapular artery and if needed the subscapular artery. A counter incision in the axilla can be helpful to expose and dissect the subscapular system.

Flap combinations

Scapular Osteocutaneous Flap: The flap can be taken with a segment of lateral scapula on branches from the circumflex scapular flap to the scapula bone. See scapula bone flap.