Wound Closure

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Chapter 122 Wound Closure

Soft Tissue Anatomy

The first layer deep to the skin is the subcutaneous tissue. Within this layer can be found a thin membranous layer of fascia,1 recently termed the iliolumbar membrane, in the back.2 Deep to the subcutaneous tissue in the cervical spine are three layers of musculature, of which the trapezius makes up the superficial group. This muscle has descending, transverse, and ascending portions originating from the superior nuchal line of the skull, the ligamentum nuchae, the spinous processes of C7-T12, and the supraspinous ligament.3 Immediately deep to the trapezius in the midline is the ligamentum nuchae. It is the cervical extension of the supraspinous ligament, attaches to the inion,4 and has connections with the lesser posterior rectus, splenius, semispinalis capiti, and the lesser rhomboids.5 The intermediate cervical muscular layer includes the splenius capitis and cervicis; semispinalis capitis and cervicis; and longissimus capitis and cervicis.5 The splenius muscles originate from the ligamentum nuchae and the spinous processes of the lower cervical and upper thoracic vertebrae, whereas the longissimus and semispinalis muscles originate from the cervical and upper thoracic transverse processes.5 The deep cervical musculature includes the multifidus, rotatores, spinalis, and interspinales groups.3 Rostral to C2 the deep musculature is termed the suboccipital musculature and consists of the rectus and obliquus capitis groups.3,6

The superficial muscular group of the thoracolumbar region includes the trapezius, described in the preceding paragraph, and the latissimus dorsi, originating from the dorsal layer of the thoracolumbar fascia from the spinous processes of T7 to the sacrum and the iliac crest.3 The thoracolumbar fascia is multilayered and arises from the aponeurosis of the transversus abdominis.4,6 The thoracolumbar fascia attaches medially to the spinous processes of the lumbar and sacral vertebrae and caudally to the iliac crests. Laterally, it attaches to the ribs and intercostal fascia. The dorsal layer of the thoracolumbar fascia is termed the lumbar aponeurosis and serves as the origin of the latissimus dorsi muscle. The intermediate muscles of the trunk include the rhomboids and serratus posterior.4 The deep muscles of the back are divided into lateral and medial tracts. The iliocostalis, longissimus, and intertransversarii muscles make up the lateral group; the rotatores, multifidus, and interspinales make up the medial group.3 The trapezius muscle spans the entire breadth of the interscapular distance and extends from the subocciput to T12. The latissimus dorsi muscle likewise extends from T7 caudally to the sacrum. By virtue of their location and breadth, they provide a ready mechanism for the closure and repair of open spinal wounds.

Wound Closure

The basic principles and tenets of wound closure apply to surgical spinal wounds. Preoperative conditions that interfere and compromise wound healing should be corrected, where possible, to provide the best environment for closure and healing following a surgical procedure. Likewise, meticulous care should be taken throughout the operative procedure to minimize tissue damage and destruction where practicable, thereby reducing surgeon-induced impediments to wound closure/healing.

Dorsal Spinal Wounds

The technique for closure of dorsal spinal wounds is similar in the cervical and thoracolumbar regions. In procedures involving dural openings, whether intentional or inadvertent, every attempt at a watertight dural closure should be made. Nonabsorbable #6-0 polypropylene sutures generally are used, with or without a fascial autograft, or commercially available dural substitute allografts. The suture line is covered with a layer of fibrin glue, or, more recently, with the sealant DuraSeal (Covidien, Waltham, MA). Where there is concern regarding the quality of closure, a spinal drain should be placed. Failure to achieve adequate dural closure may lead to a variety of complications, including meningitis, arachnoiditis, pseudomeningocele formation, and cerebrospinal fluid (CSF) leakage from the wound. In the latter case, it is imperative to return to the operating room, readdress the CSF leak, and avoid the temptation to simply reinforce the skin closure.

After dural closure, inspection of the deep tissues, including the resected vertebral bone edges, epidural contents, and surrounding musculature, should be performed to ensure that meticulous hemostasis has been achieved. Failure to do so may lead to postoperative hematomas, which can become symptomatic due to compression of neural structures. Epidural bleeding should be controlled with bipolar cautery or local hemostatic agents, the exposed bone edges waxed, and muscular bleeding likewise controlled with cautery. Irrigation with hydrogen peroxide often is performed in cases without dural violation, particularly in large wounds, to aid in hemostasis. Once this has been achieved, some surgeons also cover exposed dura with a local hemostatic agent.

One of the central tenets of wound approximation is the use of an orderly layered closure to optimize wound healing by eliminating dead space to reduce the risk of fluid collection and infection. After the dura has been closed and hemostasis achieved, attention should be turned to the layered closure. After extensive spinal procedures, a large potential dead space exists that is amplified in patients who have undergone laminectomy at multiple contiguous levels. The paraspinal musculature is approximated with a few large absorbable #0 sutures, with care taken not to strangulate the tissue, which can cause local muscle necrosis and severe postoperative pain. Fascial closure is performed carefully with interrupted #0 absorbable sutures. In cases of reoperation, or where radiation is anticipated, nonabsorbable braided #0 suture material is recommended. A tight closure of the fascia is recommended to reduce dead space as well as prevent possible CSF leakage. This layer also may serve as a barrier to the development of a deep infection from a superficial wound infection. Placement of a drain into the epidural and/or subfascial space should be considered in those patients with large wounds, after vascular tumor removal, after instrumented fusion procedures, and after operations for trauma. These drains diminish the occurrence of hematomas and seromas that hamper wound healing7,8 and that also can cause neurologic deficit with neural element compression. If CSF is observed accumulating in the suction canister, the drain must be removed immediately to prevent a persistent CSF leak and complications associated with CSF overdrainage.

In larger individuals, it may be necessary to close the subcutaneous tissue in multiple layers owing to its thickness. For this, #2-0 Vicryl suture is commonly used, and the membranous superficial fascia, most easily identified in the lumbar subcutaneous tissue,1,2 should be the target of reapproximation. The dermal tissue is reapproximated next with inverted interrupted #2-0 or #3-0 suture material, taking care to align the edges of the wound in the rostral-caudal as well as dorsal-ventral dimensions. It is important to produce wound eversion with closure of this layer to ensure the skin layer will have minimal tension after its closure, thereby improving its ability to heal. Scars from properly everted wounds tend not to widen with time, and the ridge of everted tissue always settles to normal.9 The skin is reapproximated with either monofilament suture, staples, or, in some cases, skin adhesive application.

Ventral Spinal Wounds

Closure of wounds from ventral or lateral thoracolumbar approaches also should adhere to the basic principles of wound closure. Closure or patching of CSF leaks, meticulous hemostasis, placement of drains when appropriate, and orderly layered closure with emphasis on a watertight fascial reapproximation should be performed. These operative approaches often are performed by vascular, thoracic, or general surgeons, and the spine surgeon should participate in the subsequent closure of these wounds.

The reapproximation of anterior cervical spinal wounds, while much less tedious than posterior closures, still must be tackled in meticulous fashion. As with posterior wounds, CSF leakage should be formally addressed and the leak closed if possible. With or without closure, spinal drainage at the end of the case is recommended, and will save the surgeon several agonizing sleepless nights. The spine surgeon should be fastidious with hemostasis, because postoperative hematomas have the potential to be life threatening due to airway compromise. Placement of a drain is not a substitute for adequate hemostasis. The musculature of the neck is not reapproximated, unless it was intentionally divided, which occasionally may be the case with the omohyoid. The watertight fascial closure for the anterior neck is the platysma. It often is easily identified in young patients, but it may be quite atrophied and difficult to discern in elderly patients. In obese patients, it often is infiltrated with adipose tissue, which occasionally makes its identification difficult. The platysma often is closed with #3 Vicryl suture and is followed by reapproximation of the dermis with inverted #3 Vicryl sutures as well. Some surgeons skip deliberate closure of the dermis and instead proceed to a subcuticular closure with an absorbable monofilament suture. Skin adhesives or Steri-Strips may be placed at this point, depending on surgeon preference.

In the presence of wound dehiscence or infection before attempted closure, extensive debridement is necessary. In cases in which radiation therapy has been received preoperatively or is anticipated postoperatively, closure of the fascia should be accomplished with nonabsorbable #0 or #2 monofilament or braided nylon. Wound closure in general is uncomplicated in the cervical and lumbar region because of the thickness of the muscle layer and the lordotic curvature of the spine. An incision in the upper thoracic spine is subject to horizontal tensile forces caused by shoulder movement, and this area is notorious for dehiscence in as many as 30% of patients with cancer or spinal implants.10 In addition to spinous process excision, a figure-8 brace may be worn postoperatively to reduce tensile forces across the vertical incision. Drains usually are left in place for 2 days, or until the drainage is less than 50 mL per 8-hour shift. Sutures are not removed until at least 2 weeks postoperatively.

When the quality of the tissue present at the wound edge or the amount of tissue damaged or missing precludes primary closure, one must consider either a skin graft or some other type of flap closure. Split-thickness skin graft can be used for closure in rare instances in which the underlying soft tissue is adequate to protect underlying structures and has adequate circulation to support survival of the skin graft. Modern electric-powered and nitrogen gas pressure–powered dermatomes make the harvest of high-quality split-thickness autograft a simple and predictable procedure. Graft may be taken from any suitable donor site, usually at a thickness between 0.012 and 0.015 inches. This is applied to the wound bed. Fixation of the graft for 4 to 5 days prevents movement between the graft and the recipient bed and usually results in graft acceptance.

Myocutaneous Flaps

Closure of large soft tissue defects currently relies heavily on the use of myocutaneous and fasciocutaneous flaps. In the back, the most commonly used musculocutaneous flap for defects of the upper third of the thoracic spine is the trapezius muscle. Variations of flap design can cover upper-third defects over a relatively wide arc of rotation, as long as the transverse cervical artery is intact. Defects in the middle third of the back are most commonly closed using the latissimus muscle, a choice based on its thoracodorsal blood supply or on the paraspinous perforators. Defects of the lower third of the back often are closed with gluteus muscle myocutaneous flaps, most often based on the inferior gluteal artery. In the lower third, the latissimus dorsi muscle also may be used. Its use must be based on a free flap using vein grafts from the thoracodorsal trunks or by anastomosis to the superior or inferior gluteal vessels, if it is to reach the caudal-most portions of the lower third of the back.

Trapezius Muscle and Myocutaneous Flaps

Because of its length, extending from the superior nuchal line to the spinous process of T12, and its width, from one acromial process to the other, the trapezius muscle is suitable for rotation, with or without overlying flaps of skin (Fig. 122-1). The blood supply to the trapezius muscle is via the type II vascular pattern characterized by one dominant vascular pedicle with other minor contributing pedicles.1113

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