Composite bone and soft tissue injuries represent a difficult problem for orthopaedic trauma surgeons. Unique anatomic considerations make the tibia especially vulnerable to complex wounds associated with open fractures. The anteromedial border of the tibia is particularly at risk due to its lean soft tissue envelope. Wound coverage reduces the risk of infection and improves local blood supply. Management of wounds and treatment of infection commonly require rehospitalization after extremity trauma.1 Infectious and soft tissue complications, such as flap failure, contribute to late amputation after attempted limb salvage.2,3
Orthopaedic surgeons treating acute fractures and sequelae of previous trauma (eg, nonunions and osteomyelitis) increasingly recognize the importance of a healthy soft tissue envelope. Extremity shortening and angulation are surgical strategies that concurrently address bony and soft tissue injuries. These limb salvage techniques have been used to successfully reconstruct bone and soft tissue defects involving the tibia and lower leg, including Gustilo–Anderson IIIB tibial fractures and infected tibial nonunions.4–8
Multi-system injuries, ipsilateral fractures, vascular compromise, and neurologic injury commonly accompany high-energy extremity trauma. These issues can be addressed before or concomitant with definitive soft tissue procedures. Modifiable risk factors like tobacco use, preoperative opioid use, hyperglycemia, endocrine deficiencies, and malnutrition are addressed and ideally mitigated before reconstruction.
SOFT TISSUE RECONSTRUCTION
The soft tissue reconstructive ladder is an oft-cited algorithm designed to illustrate progressively complex strategies for wound management. The advent of new techniques and an influx of promising technology have increased the surgical options available to orthopaedic and plastic surgeons. Gottlieb and Krieger9 emphasize that a step-wise approach to complex surgical problems is not necessarily the most practical method, however. The authors write, “reconstructive surgery calls for parallel, creative thought rather than simple sequential thought. One must be free to skip a rung of the ladder and take the elevator up to the next floor.” This guidance is particularly applicable to surgeons treating complex lower extremity injuries because the traditional soft tissue reconstructive ladder does not incorporate techniques for addressing bone loss. In this setting, treatment options are influenced by the size, location, and chronicity of a wound; the mobility of local soft tissues (including scar); and the size and location of the underlying bone defect. We propose a modified reconstructive ladder incorporating strategies to address increasingly complex combined bone and soft tissue defects (see Figure, Supplemental Digital Content 1, http://links.lww.com/JOT/A138).
The reconstructive ladder also assumes that treating physicians have at their disposal the skills and resources necessary to execute all rungs of the ladder. In reality, many treatment centers (particularly those in less developed areas or in austere environments) do not have access to a skilled microvascular surgeon. In contrast, the strategies reviewed in this article use techniques familiar to the orthopaedic trauma surgeon and can be put to use in the absence of a microvascular surgeon.
Free and Rotational Flaps
In many centers, coverage of large lower leg soft tissue wounds consists mainly of rotational and free (microvascular) flaps performed by plastic or other microvascular-trained surgeons. Local and free flaps have been successfully used together to cover massive lower extremity wounds.10,11 There is conflicting data about the clinical success of rotational versus free flaps for treatment of soft tissue wounds. Even the largest studies, all retrospective, are confounded by variations in injury type and surgical timing such that no clear conclusion about the superiority of one technique over the other can be made.3,10,12,13 Furthermore, authors agree that rotational and free tissue transfer carry important risks, including flap necrosis and failure, wound complications, infection, donor site morbidity, vascular insufficiency, need for delayed weight bearing, and difficulty elevating flaps for secondary procedures such as fracture fixation or bone grafting. Need for flap elevation and flap failure are 2 of the most common complications plaguing patients undergoing limb salvage.14 Finally, there are several limb, host, and surgeon characteristics that make patients poor candidates for a flap (see Table, Supplemental Digital Content 2, http://links.lww.com/JOT/A91). In these situations, alternatives to flap coverage should be pursued.
Shortening and angulation strategies can be used to manage extremity injuries associated with large regions of devitalized bone, segmental bone loss, and/or large soft tissue wounds. During deformity correction, distraction histogenesis creates new soft tissue in a similar manner to tissue expanders. Acute shortening alone is used for small lower extremity defects where the resulting limb length difference can be addressed by an accommodative shoe lift (usually less than or equal to 2 cm). For moderately sized defects, shortening can be combined with limb lengthening via bone transport to restore limb symmetry and length. For large or asymmetric defects, an angular deformity can be introduced with the wound at the concavity of the deformity to facilitate wound closure. For the largest wounds, rotational flap coverage can augment combined shortening, angulation, and rotation in a strategy known as gradual expansion muscle (GEM) flap coverage.
Physiology of Soft Tissue Distraction
Bone growth in response to gradual distraction is known as distraction osteogenesis. Likewise, soft tissues' ability to change in response to stretch is termed distraction histogenesis. In response to gradual mechanical stretch, soft tissues such as skeletal muscle and tendon units proliferate (rather than stretch) and undergo biologic changes at the cellular level. In animal models, muscle distraction leads to an increase in sarcomere number and a decrease in muscle fiber length.15 It activates satellite cells and promotes cellular proliferation in the damaged area, increasing overall muscle length.16 During expansion, skeletal muscle architecture remains unchanged while its vascular network improves.15 Cellular proliferation inversely correlates with age for both skeletal muscle and tendons, occurring 2 to 3 times faster in younger animals. In murine models, tissue expansion induces changes in the subcutaneous tissues, including vascular remodeling and an increase in adipocyte count.17
Importantly, changes in skeletal muscle can occur in the absence of nerve stimulation.18 In animal studies, nuclear enlargement, nuclear proliferation, and cellular invasion/spread have been observed in skeletal muscle as it hypertrophies in response to stretch. This process, known as the tension stress effect, explains why denervated muscle bellies used for rotational flaps can stretch and adapt in response to changes in limb alignment, a process exploited by the GEM flap technique.
Shortening With or Without Angulation
Acute shortening simultaneously addresses both bony and soft tissue injury: Compression of the bone edges promotes osteosynthesis, whereas shortening the length of the wound may help avoid a complex soft tissue procedure, such as a rotational or microvascular flap. This technique is particularly useful for transverse or circular wounds, which could not otherwise be closed with the limb out to its original length. When arterial or peripheral nerve injuries are present, primary shortening can facilitate direct anastomosis or primary neurotization.19
There has been no definitive consensus about the maximum length of acute shortening. Many surgeons reference the recommendation of Sen et al that acute shortening be limited to 3 cm.7,8,20,21 Others report that middle and distal tibial defects can routinely accommodate up to 6 cm of acute shortening.6 Tibial defects up to 22 cm have been successfully treated with these techniques.22
Vascular perfusion and soft tissue compliance (possibly due to chronic infection, vascular disease, or scar) can limit the degree of limb shortening. Extreme shortening and angulation can precipitate vascular kinking or spasm. Atbasi et al23 performed angiography 7 days after acute limb shortening and detected mild arterial “bending” in patients with 4–6 cm of shortening. Despite shortening up to 8 cm, no patient developed kinking or occlusion of large peripheral arteries. Vascular patency and architecture were preserved at 2-year follow-up. Similar results of acute shortening up to 8 cm have been described elsewhere.24 The amount of shortening should be carefully guided by intraoperative Doppler vascular examination both before and after the technique is performed. We do not routinely obtain preoperative or postoperative vascular studies unless the history, injury pattern, or clinical examination raises suspicion for a vascular injury.
Limb lengthening can accompany or follow acute shortening when the limb length discrepancy exceeds 2–3 cm. Compression through the defect (eg, fracture) and distraction through a corticotomy outside the zone of injury can be performed simultaneously or in succession. A remote corticotomy improves the biology of the limb by increasing blood flow to the extremity 4- to 5-fold.25 A circular ring fixator such as an Ilizarov frame or a computerized hexapod system like the Taylor Spatial Frame (Smith & Nephew, Memphis, TN) allows correction in multiple planes (ie, concurrent improvement in angulation, rotation, and translation). If necessary, multiple corticotomies can be used for tandem segment transport to address segments greater than 6 cm.7,26
Authors' Preferred Technique
First, devitalized bone is resected in its entirety using osteotomes with predrilling or an oscillating saw cooled by a moist sponge.27 Punctate bleeding at its leading edge heralds healthy cortical bone. In the setting of fracture or nonunion, a transverse osteotomy can create a stable surface and maximize contact between the cut surfaces. A similar (but often smaller) fibular defect is required to accommodate tibial shortening.
The most critical step of the technique is to assess and document distal pulses using Doppler ultrasonography. The number of vessels (quantity) with a signal and the quality (triphasic, biphasic, or monophasic) of the signal must be documented. This process is repeated after an acute deformity is induced. Any change in the quality of the Doppler signal necessitates further action. At all points after limb deformation, the quantity and quality of Doppler signals should remain the same.
After initial vascular assessment, the limb is shortened to allow contact between skin edges. If necessary, an angular deformity is slowly induced with the wound in the concavity of the defect. Ideally, shortening with or without angulation allows primary closure of the wound. If the skin cannot be closed, local muscle from the induced deformity can at times be recruited and approximated to adjacent muscle or to the skin edge. Split thickness skin grafting onto healthy muscle can complete the coverage.
Occasionally, a large defect or poor soft tissue compliance precludes acute shortening and wound closure. In this situation, gradual shortening using a frame can be performed at a rate of 2 mm per day.6 Gradual shortening via compression at the fracture site may also be used when the bone edges at the docking site are asymmetric.5
At times, the amount of shortening or angulation needs to be reduced until a normal Doppler signal returns. If decreasing the induced deformity puts unacceptable tension on the closure, twisting the limb to re-tension the vessels is attempted. If the quantity and quality of pulse signals returns to baseline, the new deformity is accepted. Otherwise, gradual deformity creation or GEM flap should be used.28
Next, the limb is stabilized using an external fixator. We prefer to use a computer-guided hexapod frame for induced deformity correction. A proximal or distal metaphyseal corticotomy can be created remote from the fracture site either primarily or during a second operation to restore limb length.
When the epithelium is healed (whether a skin graft is used or not), controlled deformity correction begins through the frame. This generally follows a latency period of a few days to a few weeks. We leave sutures in place until the completion of deformity correction to avoid wound complications. Correction of the induced angular deformity at the fracture site and lengthening through the remote corticotomy can occur in succession or simultaneously. Fine tuning of the deformity correction is afforded by software-driven hexapod fixators.
Several authors report promising results after various combinations of shortening, angulation, and bone transport for treatment of composite bone and soft tissue defects (see Figure, Supplemental Digital Content 3, http://links.lww.com/JOT/A139).
Sen et al managed 24 patients with Gustilo–Anderson IIIA or IIIB fractures with acute shortening.21 The cohort had mean bone and soft tissue defects of 5 cm (max 8.5 cm) and nearly 9 cm2 (max 50 cm2), respectively. Soft tissue wounds were closed primarily (acute shortening) in three-quarters of patients and in delayed fashion (gradual shortening) in one-quarter of patients. The authors reveal that 52 complications occurred in 18 patients for a mean complication rate of 2.08 complications per patient. The most common complications were soft tissue inflammation/infection, pin tract infection, and delayed regenerate maturation at the site of bone transport.
Rozbruch et al present their results of 25 patients with acute open tibial fractures or tibial nonunions treated for composite bone and soft tissue loss.7 Two limbs had a history of previous flap failure. Mean bone and soft tissue defects after debridement measured 6 cm (max 14 cm) and 10 cm (max 25 cm), respectively. One group was treated with shortening alone while the other was treated with acute shortening and lengthening via bone transport. The authors note that patients who experienced shortening alone had mean 1.7 cm limb length deficit, whereas patients who underwent concomitant lengthening regained approximately 5.6 cm of length. The authors recommend that trifocal bone transport be considered for patients with bone defects greater than 6 cm.
El-Rosasy used shortening and bone transport in the treatment of 21 open tibial fractures (Gustilo–Anderson IIIA or IIIB) or tibial nonunions associated with large soft tissue defects.6 The mean bone defect after debridement was 4.7 cm. All but 1 patient underwent primary wound closure after shortening; this patient had a split thickness skin graft placed. One patient developed a deep infection and draining sinus tract; after surgical debridement, a rotational flap was used to cover the new soft tissue defect.
Nho et al used shortening and angulation to treat an infected tibial nonunion.4 Debridement of dysvascular bone produced a 6-cm bone defect, which was acutely shortened. A 20 degree apex–posterior deformity was induced to facilitate primary wound closure. The authors report excellent outcomes, including function knee and ankle motion, equal leg lengths, and painless independent gait, at 1-year follow-up.
Lerner et al describe their group's experience employing extreme limb shortening to treat a traumatic diaphyseal tibial defect 22 cm in length with an associated 240-cm2 wound.22 A 50 degree apex-posterior deformity was created to allow primary wound closure and hinged Ilizarov frame was placed. No soft tissue procedures were performed. Once the angular deformity was corrected, bone transport was performed through 2 metaphyseal corticotomies in staged fashion (separated by a 3-month interval). At the end of treatment, the patient had excellent adjacent joint motion, had no limb length discrepancy, and was table to return to work and sport.
Hsu and Beltran describe the use of shortening and angulation using static monolateral external fixators in an austere environment where an amputee would be unlikely to obtain a prosthesis.28 In this setting, a healed shortened—or even angulated—limb is arguably more functional than an amputation without a prosthesis. Patients have the option of undergoing late osteotomy, bone grafting, and deformity correction should the opportunity and resources arise.
Beltran et al report their experience with the GEM flap technique in 5 patients with segmental tibial bone loss up to 17 cm and a large anteromedial lower leg soft tissue defect not amenable to primary wound closure or rotational tissue transfer.29 Patients underwent mean acute shortening of 5.3 cm and mean combined angulation of 30.4 degrees varus and 20.6 degrees recurvatum. A latency period of 16 days was observed between the 2 stages. No wound complications, flap complications, or deep infections were reported. One patient underwent autogenous bone grafting, one required revision osteotomy for early fibular consolidation, and a third underwent late amputation for persistent tibial osteomyelitis. The remainder progressed to independent mobility after deformity correction, frame removal, and rehabilitation.
Inducing and gradually correcting a tibial deformity with shortening and angulation techniques affords the orthopaedic trauma surgeon the opportunity to use distraction histogenesis to reconstruct composite bone and soft tissue defects in challenging situations.
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