Additional videos related to the subject of this chapter are available from the Medizinische Hochschule Hannover collection. The following video is included with this chapter and may be viewed at expertconsult.inkling.com :
Introduction and General Principles
The optimal soft tissue characteristics required for coverage of defects involving the upper and lower extremity vary according to the site and location of the defect. Characteristics of interest include pliability, durability to withstand the wear and tear of movement and friction (from work as well as clothing), the ability to cover large surface areas with minimal thickness, and cosmetic appearance. These features allow the best functional outcome, maximally protect the vital structures of the extremity, and optimize the aesthetic result. In addition, the general requirements of any soft tissue reconstruction, including minimal donor site morbidity and minimal disruption of local vasculature, become more critical when considering the functional restoration of the extremity. Although soft tissue defects can occur from a variety of conditions (trauma, tumor, or infection), soft tissue coverage remains a vital operative intervention that protects underlying vital structures, such as nerves, tendons, blood vessels, and bone, preserves the integrity and continuity of musculoskeletal elements, prevents functional disability, and promotes an acceptable aesthetic result. Techniques include primary wound closure, delayed primary wound closure, skin grafting, local random flaps, axial pattern flaps, island adipofascial and fasciocutaneous flaps, muscle or myocutaneous pedicled flaps, and microvascular free-tissue transfer, or free flaps. Optimal choices depend on the extent of the defect and available soft tissue donor sites.
The concept of the “reconstructive ladder,” or choosing the simplest closure or coverage option available, has been at the forefront of soft tissue reconstruction since its description by Mathes and Nahai in 1982, and assists the surgeon in choosing the best coverage option. However, this approach assumes the coverage technique as the important outcome of interest, and may not optimize the reconstruction plan or optimize the functional result in more complex cases. When this is the case, it may be prudent to choose the more complex option to facilitate the reconstruction plan and functional outcome. This paradigm has been described as the “reconstructive elevator” ( Table 18-1 ).
The detailed patient assessment is critical to the success of any soft tissue repair or reconstruction. The general condition of the patient and the ability to withstand reconstruction must be carefully determined. Included in this analysis is the causative aspect of the defect. In cases of trauma, the antecedent injuries need to be factored; mechanism of injury, degree of energy imparted to the soft tissues, and presence of contamination will significantly impact the surgical plan. A quick analysis of the clinical problem with a template of reconstructive choices is an important and essential step at this point. Ensuring treatment will occur in the correct facility, with the appropriate resources and expertise emphasizing a multidisciplinary approach to care, will ensure the optimum outcomes.
The typical approach used by plastic and reconstructive surgeons is to devise a patient-specific surgical plan that includes contingencies for every possible extent or type of defect. This is particularly important in extensive trauma, wherein the final defect after required tissue débridement may be quite different than anticipated. An algorithm, or list of options, for soft tissue reconstruction is often useful and will help the surgeon organize the surgical plan, but in the end, all plans must take a customized approach to the patient. A reconstructive management strategy is based on the evaluation of the defect and the patient’s specific functional needs. The mechanism of injury, the location and extent of the wound, tissue viability, contamination, and exposure of vital structures are all critical considerations. A plan for concurrent acute and definitive fracture care must be coordinated with the trauma team, and within the scope of wound care.
Most reconstructive surgeons favor immediate reconstruction, except when the defect demands a delay. In high-energy injury patterns, in cases of infection, or in heavily contaminated wounds, it may be necessary to delay definitive wound closure or coverage until an adequate, multistaged evaluation and débridement may be performed. Vacuum-assisted closure (VAC) dressings have improved treatment of open wounds, and may allow some additional delay in flap reconstruction without expectation of further morbidity. However, the general trend supported by the literature remains to cover tissue as soon as the injured patient and limb are optimized, even if this extends past the 72-hour window proposed by Godina.
A healthy wound bed begins with the meticulous and complete surgical removal of foreign material, infection, and devitalized tissue. Chronic wounds should be converted to acute wounds to promote healing. In acute injury, wounds must be extended past the zone of injury to ensure complete treatment as well as effective débridement is accomplished. Judicious use of lavage may help remove foreign matter, but care must be taken not to extend the zone of contamination by forcing debris into the surrounding tissue. Use of a tourniquet early in the case in important to best visualize all contaminants and devitalized tissue and avoid injury to vital structures such as nerves and blood vessels. The tourniquet should be released prior to closure or dressing application to confirm removal of all devascularized tissue and to ensure adequate hemostasis.
A systematic approach to wound débridement achieves the best results, and sharp débridement is the cornerstone of this surgical technique. Excision of all devitalized tissue to a healthy tissue margin, instead of a “wait and see” approach to suspect tissue, will limit persistent contamination and infection. All nonviable or suspect tissue is sharply débrided from the wound until a healthy margin of viable tissue is achieved. Every effort to preserve nerves and blood vessels crossing the zone of injury is made, and if they are transected, these structures are carefully tagged with dyed monofilament suture and documented in the operative records so that they may be more easily visualized during later wound débridement or reconstructive efforts.
Identification of nonviable tissue remains a challenge, and there is no substitute for experience. Knowledge of anatomy and local blood supply is paramount in this endeavor as overly aggressive débridement within muscle compartments may devascularize previously viable tissue. Tendon débridement must be carefully considered due to potential loss of function. Tendons are also easily desiccated, especially if overlying paratenon or sheath is missing. Injured blood vessels or nerves must be carefully assessed for primary or delayed repair or grafting. Smaller sensory nerve branches may not be amenable to salvage, and if so, we like to pull traction on the proximal end, cut sharply, and allow retraction into the soft tissues. If the stump cannot be retracted, we make every effort to bury it in muscle. Local soft tissues should be used to cover exposed tendons, nerves, and vessels to prevent further injury.
Devascularized bone fragments must be removed from the wound bed, with the exception of substantial articular fragments, which should be retained in an attempt to preserve the articular surface. Curettes, rongeurs, and burs are useful to check for punctate bleeding indicative of healthy bone that should be preserved. Culture of any contaminated or osteolytic bone will help guide antibiotic selection.
Strict hemostasis is critical to prevent hematoma and limit further infection and morbidity caused by blood loss. Suture ligatures and surgical clips should be used for larger vessels, Bovie or bipolar cautery for smaller vessels. Braided suture is typically avoided when possible to avoid harboring bacteria. Judicious use of a tourniquet is helpful to identify and control large bleeding vessels and includes release to assess hemostasis prior to closure, grafting, or dressing application. Adjunctive topical hemostatic agents are available and have been used successfully in some of our most severely war injured patients. Lavage is important for removal of foreign debris and lowering bacterial counts. Gravity or bulb irrigation is considered the standard, whereas pulsatile lavage can further damage delicate tissues exacerbating the potential for adhesions and functional loss.
Negative-pressure wound therapy dressings are a great advance in the treatment of wounds not amenable to primary closure. V.A.C. Therapy dressing is commonly used to manage large wounds from high-energy injuries. It continues to débride wounds, reducing edema and local bacterial counts, while promoting growth of healthy granulation tissue. It also eliminates the need for multiple daily dressing changes, thereby reducing the patient’s discomfort and nursing staff workload. It is prudent to limit exposure of blood vessels, nerves, or tendons to the wound VAC and try to rotate available local tissue to provide coverage prior to placement of the wound VAC.
Eliminating contamination and infection is essential to successful wound treatment. In addition to appropriate broad-spectrum antibiotic use, there are many different options available that can be tailored to the clinical or surgical situation to provide local infection control. Antibiotic bead pouches or fracture spacers have been used effectively to provide local infection control in cases of wounds with associated high-energy fracture patterns. With comminution and bone loss, soft tissue space can be maintained for future reconstruction and enhanced mechanical stability provided. In highly resistant bacterial infection silver-impregnated films, colloidal materials, wound VAC sponges, and distillation solutions are additional options for the surgeon and have been used with great frequency at our institution. For extremely large wounds with highly resistant bacterial colonization or infection that are not amenable to wound VAC treatment, mafenide acetate (Sulfamylon) or Dakin’s soaked wet-to-dry dressings have proven effective and resulted in successful wound closure. Infectious disease specialty assistance is recommended in such cases.
When wounds are associated with fractures in the acute setting, provisional stabilization should be attempted to maintain soft tissue space, prevent mechanical agitation of the surrounding tissues, and optimize pain control when definitive fixation is not advisable. In general, external fixators and Kirschner wires are preferred acutely with conversion to definitive fixation as indicated by the injury, especially in the setting of high-energy injuries, such as blast injuries, when large amounts of debris are forced into the wounds with tremendous energy and the level of contamination is typically higher than that seen in most blunt open trauma.
For highly contaminated wounds, or when there is concern for viability in critical areas or structures, repeat operative débridement should be planned every 24 to 36 hours until a healthy, vascularized soft tissue bed is achieved ( Table 18-2 ).
Wound Coverage Types
Split-thickness skin grafts are a good coverage option for simple wounds that cannot be closed primarily and have a healthy wound bed. By definition, split-thickness skin grafts remove the epidermis, but only partially harvest the dermis, allowing for regeneration of epidermis at the harvest site. The thickness of the graft will determine the potential of graft contraction, with thinner grafts contracting more and thicker grafts contracting less. This thinner graft may be advantageous when the wound condition dictates contracture to a smaller wound; conversely, a thicker graft may be preferred when wound contracture is not desired, such as crossing a joint. In a healthy wound bed, split-thickness skin grafts are reliable, and can be meshed to cover a larger area than harvested from the donor site. Graft harvest requires specialized equipment, and cosmetic donor site morbidity can be expected when a large volume of skin graft is required.
Full-thickness skin grafts, by definition, remove the entire epidermis and dermis of the affected area, requiring primary closure. Advantages of full-thickness skin grafts are reduced graft contracture and enhanced durability. For this reason, they are typically employed in the hand. Disadvantages include limitation in recipient site coverage.
The past several decades have seen significant research and interest in dermal substitutes for a variety of applications, including burns and complex wounds. Perhaps the most commonly reported dermal substitute for wound coverage is Integra (Integra Life Sciences, Plainsboro, NJ), an acellular bilaminate membrane composed of cross-linked bovine tendon collagen and chondroitin-6-sulfate. Integra is most commonly used in a meshed bilayer construct with the addition of a silicone layer to prevent desiccation. Dermal substitutes such as Integra are easy to use or apply, limit donor site morbidity, are readily available, and have a proven track record in burn patients and complex extremity wounds. In many cases, use of Integra has eliminated the need for complex flap reconstruction and its associated morbidity. Coupled with a split-thickness or full-thickness skin graft, usually performed 14 to 21 days after initial application, Integra has provided reliable coverage of complex wounds with exposed muscle, tendon, and even bone. However, successful coverage has not been proven with application directly over fracture. The disadvantages of dermal substitutes are the financial cost of implant, and the inherent lack of antimicrobial properties prompting the use of additional antimicrobial dressings that may increase cost. Negative-pressure wound therapy is now commonly used with Integra application, and may accelerate healing and time to skin graft placement. In addition to primary coverage of complex wounds, Integra has been used to decrease donor site morbidity in flap surgery by providing a more supple, durable coverage. Integra has also been used effectively to provide durable coverage of amputation stumps that allow functional prosthetic usage.
Random Pattern Flaps
By definition, random skin flaps have no named blood vessels, and rely on the subdermal vascular plexus for perfusion. This limits the geometry of the flap, requiring that the length of the flap be no more than twice the base of the flap to ensure flap blood flow. Longer flap geometries have been described, but flap viability may be compromised, and when this occurs, it will be at the distal extent of the flap. This type of flap requires mobile skin, and the donor defect can usually be closed, although the addition of a Z-plasty may be required.
Axial Pattern Flaps
Axial pattern flaps are fasciocutaneous flaps designed around a named artery and vein. The groin flap is a classic example of this flap, designed around the circumflex scapular artery and vein. Axial pattern flaps have the advantage of supplying a much larger flap than random pattern flaps, and due to a larger, more robust vascular system, can be converted to free flaps if required.
Island Pattern Flaps
Island pattern flaps are similar to axial pattern flaps, in that the flap is supplied by a named artery and venous outflow. However, as the name would imply, island flaps can be separated completely from the harvest site, and transposed somewhat distantly on its named arteriovenous pedicle. The advantage is usually ease of flap harvest and inset. The disadvantage is the potential loss of a named artery supplying distant structures. Common examples include the radial forearm flap in the upper extremity, and the reverse sural artery flap in the lower extremity. Island pattern flaps may be fasciocutaneous, involving the skin and fascia, or adipofascial flaps, preserving the skin at the donor site.
Perforator flaps are fasciocutaneous flaps that derive their blood supply from intramuscular and intermuscular septal perforators from the deep vascular arterial system. The most common example of this type of flap is the anterolateral thigh flap. Perforator flaps can be pedicled or used as free flaps. Propeller flaps are a subgroup of perforator flaps, defined as perforator flaps that are islanded and rotated into a defect. These flaps have seen increased popularity for reconstruction of small soft tissue defects in the upper and lower extremity.
By definition, a free flap is harvested, its blood supply divided, and then reanastomosed to an arteriovenous supply at the flap recipient site, usually requiring microsurgical techniques. Free flaps, or free tissue, is usually classified by its blood supply. Free flaps can include skin, fascial and subcutaneous fat, muscle, bone, or combinations of any tissue type based on its blood supply. Muscle flaps, such as the latissimus dorsi muscle flap, continue to be commonly employed in reconstructive surgery. Muscle flaps have the advantage of covering large defects, and filling three-dimensional volume defects, but may not be the best coverage option when staged reconstructive procedures, such as tendon or nerve reconstruction procedures are anticipated. Because of these limitations, fasciocutaneous and adipofascial flaps based on large named arteriovenous pedicles, or even smaller flaps based on smaller perforator vessels, have recently gained popularity among reconstructive surgeons.
Soft Tissue Reconstruction of the Upper Extremity
Selecting the optimal reconstructive option depends heavily on the location of the defect. For simplification, the following algorithmic approach divides the upper extremity into five anatomic zones: shoulder, arm (within 6 to 8 cm from elbow), elbow (including lower 6 to 8 cm of arm), forearm, and hand. Specific flaps as shown in Table 18-3 can effectively reconstruct each anatomic region.
|Simple Wound (No Exposed Bone, Tendons, or Neurovascular Structures)|
|Complex Wounds (Exposed Bone, Tendons, or Neurovascular Structures)||Shoulder|
|Wrist and Hand|
A defect that involves bone, blood vessels, and/or nerves will need a careful assessment and stepwise treatment plan. Reconstruction typically involves skeletal fixation as the starting point. All vascular repairs typically require autologous grafts. Determination for acute repair versus delayed reconstruction of any nerve or tendon injuries must be determined prior to definitive wound closure or coverage.
Intuitively, the lack of local available soft tissue generally precludes a simple reconstruction method. However, certain anatomic areas are easier to reconstruct with fasciocutaneous flaps, which provide durable coverage. These areas include shoulder, limited defects on dorsal elbow, or even in the cubital fossa. In certain situations wherein there is a healthy well-vascularized soft tissue bed comprising healthy muscle or even paratenon, a simple skin graft may be an easy reconstructive strategy. Of course, the long-term problems with graft contractures and lack of durability, usually due to thin, insensate coverage, adversely impacts the outcome.
In two critical ways, understanding the vascular roadmap becomes essential to upper extremity reconstruction: (1) identification of donor vessels and (2) understanding the impact of sacrificing a vessel for flap anastomoses. Methods of assessing vascular integrity include a simple physical examination of the pulses, an Allen test (using Doppler ultrasound confirmation both preoperative and intraoperatively), and when needed an angiogram or a magnetic resonance angiogram (MRA) is available. More recently, indocyanine green fluorescence angiography used in the SPY imaging system has gained increasing interest and use for flap design and intraoperative and postoperative flap assessment. Further work is ongoing to define its role as a reliable tool for the surgeon.
In many cases, soft tissue defects about the shoulder can be effectively addressed with local fasciocutaneous flaps. The donor site is usually amenable to primary closure (for defects <6 cm in diameter) and may need skin grafting for those that are larger than 6 cm.
Scapular and Parascapular Flap
The scapular or parascapular flap is an excellent choice for larger defects on the shoulder. It can be used as a pedicle flap or free flap, and may include bone. The pedicled parascapular flap is more commonly used for reconstruction of defects of the shoulder and axillae. Either flap easily provides a fasciocutaneous flap 15 cm in length, and has been harvested as long as 25 cm. The anatomy of the parascapular flap allows it to be harvested as a chimeric flap, soft tissue or bone harvested on a single pedicle, allowing for reconstruction of large composite tissue defects in the shoulder region. The superior aspect of the flap is centered over the triangular space, where the circumflex scapular artery nourishes the parascapular flap after it travels through the triangular space. The borders of the triangular space are made up of the teres minor, teres major, and long head of triceps. The parascapular flap may be combined with the following tissues as a chimeric flap on the subscapular vessel axis: scapular flap, scapular bone, latissimus muscle, serratus muscle, and serratus muscle with rib.
The latissimus and teres major muscles are important landmarks because flap dissection proceeds from inferior to superior 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 infraspinatus 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 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 originates from the axillary artery. The circumflex scapular arises about 1 to 4 cm 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 mm in size. Although the circumflex scapular artery is usually accompanied by two venae comitantes, the subscapular artery is typically accompanied by one vein. This flap can be rotated into the shoulder area easily and provide durable coverage with low morbidity.
The Brachium and Arm
Pedicled Latissimus Dorsi Muscle Flap
The brachium, or arm, is defined as distal to the shoulder and at least 6 cm proximal to the elbow. Defects in this region are best reconstructed with a pedicled latissimus dorsi muscle flap. It provides excellent coverage with generous amounts of soft tissue that can envelope the entire circumference of the upper arm if needed. A skin paddle can be added to monitor the flap postoperatively, and to add additional fasciocutaneous coverage. The donor site on the flank is amenable to primary closure with minimal morbidity.
The blood supply is derived from a single constant vascular pedicle (thoracodorsal artery) and the flap can be rotated into the upper arm with ease because of its long neurovascular pedicle, large size, ease of mobilization, and expendability. In some cases, it can cover soft tissue defects involving the shoulder, arm, and even sometimes the elbow. As an innervated functional muscle flap, it can improve shoulder abduction, or when rotated to the elbow, it can restore elbow flexion or extension. Detaching the humeral attachment can extend the reach of the muscle ( Fig. 18-1 ).
Pedicled Pectoralis Muscle Flap
Other options include a pedicled pectoralis muscle flap (or sometimes along with a skin paddle, which may or may not be a reliable option). Based upon the thoracoacromial trunk, this muscle extends into upper arm defects easily. Its availability is limited by the anchor point on the clavicle from, at which point the blood supply enters the muscle.
Common flap options for coverage include the reverse radial artery flap, reverse lateral arm flap, and the pedicle latissimus dorsi muscle flap. Drawbacks of these flaps include sacrifice of the radial artery, donor site morbidity, bulky flaps requiring secondary thinning, nonaesthetic donor sites, and the inability to provide sensate coverage in most cases.
Radial Forearm Flap
The traditional radial forearm flap is a common flap for coverage of large defects about the elbow. It sacrifices the radial artery and cannot be performed if the ulnar artery is insufficient to perfuse the hand. The flap is designed over the radial distal forearm and is designed to include a branch of the cephalic vein. Care is taken to preserve the paratenon during dissection over the flexor carpi radialis and brachioradialis to facilitate skin graft take over the donor site. The cephalic vein and lateral antebrachial cutaneous nerve are included in flap dissection to improve venous outflow and provide sensation to the flap. The flap is pedicled and inset into the donor site after subcutaneous transposition of the ulnar nerve. The donor site is covered with a split-thickness skin graft. Use of a dermal substitute may improve the cosmetic donor site result.
Anconeus Muscle Flap
The anconeus muscle flap may be used for the coverage of small traumatic defects around the elbow. The anconeus muscle is approximately 4 by 10 cm, and can reliably cover up to 7-cm defects. Both the medial collateral artery and the recurrent posterior interosseous artery perfuse the anconeus muscle, which anastomose within the muscle, allowing surgeon flexibility to rotate the flap on either pedicle. Common uses are to cover the radiocapitellar joint, the olecranon, and the distal triceps tendon. Primary closure is performed when possible, or in some cases, skin grafting may be required.
Pedicled Latissimus Dorsi Muscle Flap
As previously mentioned, the pedicled latissimus dorsi muscle flap may not easily reach the elbow. Detaching the humeral insertion can extend the reach. Flap elevation is performed through a posterior lateral incision. Transposition through an axillary skin tunnel and insetting over the elbow is followed by a split-thickness skin graft applied directly over the muscle. Alternatively, a skin paddle may be taken with the latissimus dorsi muscle, but the more distal it is placed (to reach the elbow), the more tenuous is the blood supply to the distal tip (which at inset covers the most important area of the defect).
Soft tissue defects in this zone with exposed vital structures (bone, blood vessels, nerves, or hardware) require free flap reconstruction. There are numerous options available depending on available soft tissue donor sites.
Anterolateral Thigh Flap
The anterolateral thigh flap is an excellent flap for coverage of forearm soft tissue defects because of its generous size, large donor vessel, and low morbidity to the patient. The perforator for the flap is located at the midpoint between the upper lateral margin of the patella and the anterior superior iliac spine (ASIS). The lateral femoral circumflex artery is easily identified by retracting the rectus femoris muscle medially. The flap can be harvested with a cuff of vastus lateralis muscle in two situations: to provide additional muscular tissue for dead space obliteration or when the perforator actually travels through the muscle itself. Harvested flap width up to an 8-cm width can usually be closed primarily. Occasionally the lateral femoral cutaneous nerve can be harvested for sensory neurotization. The flap is then inset into the defect while the vessels are anastomosed end-to-side into the brachial system ( Fig. 18-2 ).
Lateral Arm Flap
The lateral forearm flap may be used to reconstruct defects of the forearm, hand, and wrist. Substantially large defects ranging from a minimum of 5 cm to a maximum of 15 cm can be covered. The radial collateral artery, a branch of the brachial artery, supplies the flap. It wraps posteriorly around the humerus, descends on its lateral aspect and divides into anterior and posterior branches. The posterior branch supplies the lateral arm and lateral forearm flaps. The skin incision is based on the long axis of the humerus in line with the deltoid muscle insertion along the lateral intermuscular septum. Dissection identifies the biceps, brachialis, and brachioradialis muscles along the anterior plane and the triceps muscle posteriorly. The radial nerve courses posterior to the humerus from its origin at the brachial plexus and runs over the lateral aspect of the humerus. The lateral arm flap can also be harvested as an osteocutaneous flap. The wedge of bone with periosteal cuff is harvested under the septum and septal pedicle. A narrow portion of bone approximately 1- to 1.5-cm wide can be harvested ( Fig. 18-3 ).