Osteocutaneous Parascapular and Scapular Flap



10.1055/b-0034-78120

Osteocutaneous Parascapular and Scapular Flap

Goetz A. Giessler and Michael Sauerbier

The horizontally oriented scapular flap (SF) was first operated by dos Santos in 1979 and popularized by Hamilton and Morrison in 1982. Its close relative, the vertically oriented parascapular flap (PSF), was first described by Nassif et al as a fasciocutaneous flap in the same year. The first description of incorporating a bone segment from the scapula (i.e., osteocutaneous or “oc”-flap) was published in 1986 by Swartz.



Indications




  • Closure or resurfacing of medium to large defects



  • Closure of very large and complex defects by combination of PSF and SF (“boomerang” shape) or by combination with other flaps from the versatile subscapular system



  • Closure of combined skeletal and soft-tissue defects with the need of independent placement of soft-tissue flap and bone transplant by including a lateral (most common) or medial scapular border segment and/or scapular tip



  • Missing soft-tissue bulk and metacarpal structures after transmetacarpal and transcarpal amputations to prepare later toe transfer



  • Postburn axillary contractures (fasciocutaneous PSF only, free or pedicled)



Contraindications




  • Previous major injury with scarring to the posterior shoulder or scapular area and subsequent destruction of the vascular supply



  • Strongly discouraged if primary closure of the donor site is impossible due to adjacent scarring



  • Suboptimal in very obese patients, as the flap must be harvested quite large to include the pedicle safely and is too voluminous for most indications



Examination/Imaging




  • A preoperative pinch test is used to evaluate skin thickness, to estimate expendable flap size for primary closure.



  • The donor site is inspected to rule out scarring.



  • Pencil-Doppler localization of the pedicle artery (circumflex scapular artery, CSA) is unreliable because of the good vascularization of the area and high probability of misidentifying the signal.



  • Since the scapula is easily palpated, roentgenograms of the scapula are usually unnecessary in oc-PSF or oc-SF, unless there is previous trauma to the scapula, to rule out a possible fracture line in the lateral or medial rim.



  • For special indications, computerized tomography (CT) may give valuable information about the geometry of the scapula (in oc-PSF or oc-SF)



  • Angiography is not necessary.



Relevant Anatomy




  • The PSF and SF are adipocutaneous flaps overlying the course of their respective arteries, descending and horizontal branch of the cutaneous branch of the circumflex scapular artery (CSA). There is an ascending branch leading cranially to the scapular spine, which does not give rise to a separate flap, but may supply a cranial extension of a very long parascapular flap.



  • The CSA is the first branch of the subscapular artery, arising 2 cm from the origin of the subscapular artery from the axillary artery. The external diameter of the CSA is 1.72 mm. The CSA passes posteriorly through the triangular space between the long head of the triceps laterally, the teres major inferiorly, and the subscapularis medially and superiorly. It then divides into several branches deep to the teres minor. The cutaneous branch continues posteriorly between the teres minor above and the teres major below. It then turns sharply medially over the lateral border of the scapula and divides into two: one branch runs transversely, superficial to the deep fascia overlying the teres minor and the infraspinatus muscles, and the other branch runs obliquely downward, parallel to the lateral border of the scapula. Flaps based on the transverse branch of the CSA are conventionally described as scapular flaps ( Fig. 33.1c ), whereas those based on the descending branch are described as parascapular flaps.



  • Injection studies have shown that the vascular territory includes all the skin inferior to the scapular spine, extending medially toward the spine and laterally over the deltoid. The lateral border of the scapula can be harvested with either the scapular or parascapular flap as a vascularized bone graft, and it may be an option for simultaneous reconstruction of a combined dorsal hand defect and underlying metacarpal bony defect.



  • The (septo-)cutaneous branch of the CSA enters the subcutaneous adipose tissue between the teres major and minor muscles close to the lateral scapular border. The other main branch of the CSA is the infrascapular branch, located at the lateral scapular border. Direct nutrient vessels into the lateral scapular crest are short and derive at this point from either horizontal or cutaneous branches or from the CSA itself.



  • The CSA itself runs through the medial axillary gap to its origin, the subscapular artery. The other main branch of the subscapular artery is the thoracodorsal artery. Direct origin of the thoracodorsal artery from the axillary artery is found in 8% of cases.1 In those rare cases, there is no direct vascular connection between the angular branch and the CSA, and either the lateral scapular crest must be harvested on the direct branches or the angular branch must be revascularized separately.



  • The angular branch to the inferior third of the lateral scapular crest and the tip derives from the serratus branch (48.5%), from the thoracodorsal artery before the serratus branch (25%), from the thoracodorsal artery at the serratus branching (8.8%) or from the thoracodorsal artery after the serratus branch (4.4%; 13.3% other) and runs underneath the teres major muscle to the scapula, entering it through the bulk of the teres major muscle origin and the subscapular muscle.1



  • All arteries are accompanied by one or two veins.



  • Both flaps are devoid of any relevant cutaneous sensate nerves amenable for coaptation.



Pearls




  • Adipocutaneous and oc-PSF and SF and combinations thereof provide versatile chimeric transplants for combined skeletal and soft-tissue reconstruction of medium up to very large defects.



  • Various options for bone segment perfusion (direct or through angular branch or both): independent placement of the bone transplant relative to the soft-tissue flap.



  • Vascular anatomy is reliable.



  • Easy addition of various other tissue types from the remaining subscapular flap system.



  • Functional and aesthetic donor site morbidity is low, except for some widened scars in very large flaps.



Pitfalls/Complications




  • The flaps are not sensate, which limits their use in areas of grip.



  • Depending on ethnic background, considerable hairiness might be present.



  • Careful release of any scapular bone segment is necessary. Avoid levering with chisels and extending the sawcuts–fracture of the scapula or the scapular neck may occur.



  • Avoid severing the lateral thoracic nerve while dissecting the angular branch.



  • Anatomical variations may make harvesting of bone on the angular branch together with a CSA-based flap impossible: Most commonly, the thoracodorsal artery has a separate origin from the subclavian and does not derive from a subclavian artery with the CSA. In that case, consider microsurgical reattachment of the angular branch end-to-side to the CSA on back table (flap fabrication).



  • All released muscles have to be fixed with transosseous sutures, especially if some scapular tip segment was taken. This reduces hematoma formation and prevents functional impairment up to a winging scapula.



  • In female patients, consider SF-oriented or inframammary-extended PSF skin islands for better cosmesis, as the scar can be hidden in the bra line.

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Jun 28, 2020 | Posted by in PHYSICAL MEDICINE & REHABILITATION | Comments Off on Osteocutaneous Parascapular and Scapular Flap
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