Fig. 15.1
31-year-old male who suffered a moped accident with an isolated complex open intraarticular distal tibia and fibula fracture. He underwent staged management and with debridement and spanning external fixation, followed by open reduction internal fixation of the articular block and application of antibiotic impregnated beads until he healed a free latissimus flap. 5 cm of bone loss was then healed using a distraction osteogenesis technique with a proximal corticotomy in a multiplanar external fixator. The patient went on to consolidate the regenerate and heal the docking site without need for bone grafting, despite severe noncompliance with care. He currently walks without assistive device and has since had his distal tibial hardware removed due to a late infection due to shoewear breakdown of the free flap
15.2.1 Fine Wire Circular Fixation
External fixation has distinct advantages with respect to the ability to avoid direct instrumentation at sites of infected nonunions and also with the ability to slowly correct deformity, which potentially can limit the risk of injury to structures at risk. Fine wire circular fixation remains a powerful tool for both the correction of deformity and the application of distraction forces that allow for deposition of new bone. The most critical components linked to this remain to be the handling of the soft tissues during treatment (Fig. 15.2). The surgeon might choose the use of fine wire circular fixation in the setting of a nonunion that involves bone loss and angular deformity. All external fixator systems allow for multiple planes of freedom, but the use of fine wire circular fixation is the only system that allows for both elastic control and dynamic control that respect bone biology. When an in-line or even multiplanar fixator is utilized with half pin fixation alone, there is not just control of length imparted but a distinct lack of control of angulation. This lack of control is considered “parasitic” to bony healing as it is uneven and nonbiologic. With the use of fine wire fixation, the stability that is imparted will allow for healing by secondary intention and callous formation but will at the same time limit the “parasitic” lack of control of angulation [10].
Fig. 15.2
Clinical photograph of a 38-year-old male who suffered a motorcycle collision with a complex Gustilo and Anderson type IIIB open proximal tibia fracture with 10 cm of proximal tibial bone loss. This patient required careful debridement, open reduction internal fixation, and massive autologous bone grafting using a Masquelet technique after a free flap successfully healed. He ambulates without assistive device at 2 years post-reconstruction
The more popularized understanding of fine wire fixation is that it can be used in conjunction with independent distraction–compression devices that will allow for multiplanar correction of deformity by application of compression in one plane and distraction in another.
The use of fine wire circular fixation has been successfully utilized in many clinical series as outlined above to achieve restoration of skeletal alignment and length. The cost and complexity associated with these types of systems can, however, be burdensome and has lead many surgeons to unilateral frames due to the ability to achieve skeletal success and simplify the process for both the surgeon and the patient.
In this technique, the nonunion site is debrided of all nonviable tissue and bone after the removal of any preexisting internal fixation devices. A unilateral frame can then be applied in a monofocal or bifocal method. In the monofocal method, compression and distraction is initiated at the fracture site to stimulate osteogenesis. Distraction can then also be done at the nonunion site to restore leg length. If a bifocal method is done, the distraction is achieved outside of the nonunion site.
This is a widely used technique in all long bones. Harshwal et al. recently presented a series of 37 patients (7 femur and 30 tibias) all treated for nonunion within the first 8 months of the injury. Rate of union was reported at 91%. Minimal complications were noted, primarily those of pin-tract infections. These results are consistent with those reported by other authors [4, 11, 12].
15.2.2 Distraction Over Intramedullary Nails
15.2.2.1 Intramedullary Device Plus External Fixation
Given the technical difficulties of controlling transport segments during distraction osteogenesis with purely external fixation , fine wire, or Schanz pin devices, the idea of guidance of the transport over intramedullary devices has become appealing. In addition, the angular deformities introduced by the use of a unilateral rail fixator alone, in conjunction with the inability to be fully weight bearing, have demanded the ability to guide a correction over an intramedullary device.
In a recent series, Gulabi altered the original descriptions of other authors to utilize acute compression and distraction osteogenesis. These patients were all tibial diaphyseal fractures with bone loss. Custom intramedullary nails were utilized with multiple locking hole options. In this technique, the bone loss site is cleared and a distant metaphyseal corticotomy is made that liberates a transport segment. The bone loss segment is shortened up to 5 cm, and the corticotomy site is compressed. The transport then proceeds at 2 mm/day, and when docking is achieved, the site is bone grafted from the iliac crest. Their results demonstrated radiographic union, no angular deformity, a moderate amount of pin site infections, and a 0.4 external fixation index (number of months external fixator system worn divided by centimeters of distraction) [13].
15.2.2.2 Telescopic Intramedullary Restoration of Length
The problems associated with lengthening over an intramedullary nail are consistent with external fixation problems in general. These include pin-tract infections, scarring, pain, and patient comfort. In order to obviate these problems, several entirely intramedullary devices have been developed with the goal of using an internal lengthening mechanism to provide distraction osteogenesis. The intramedullary skeletal kinetic distractor (ISKD , Orthofix Inc., McKinney, TX, USA, and the PRECICE intramedullary nail (Ellipse Technologies, Irvine, CA, USA) utilize novel techniques of lengthening from within the canal (Fig. 15.3).
Fig. 15.3
55-year-old male who underwent en bloc resection of the femur for malignant fibrous histiocytoma 20 years prior to presentation. The intercalary allograft femur had healed with limb foreshortening that lead to extensive back pain and hip arthritis. Staged management included restoration of standing balance with intramedullary nail extraction and application of an intramedullary telescopic nail with proximal corticotomy through native metaphysis. At 6 months, post-op patient was pain free at the upper thigh and underwent a total hip arthroplasty with concomitant removal of hardware at 1 year
The ISKD Nail utilizes two internal rotating clutches to advance a threaded rod within the nail that is attached to the distal segment beyond an osteotomy with interlocking bolts. This provides distraction that is based on typical activities of daily living that provide stimulus through 3–9 degrees of rotation through the osteotomy site. There have been many challenges with this device including a lack of absolute control of distraction. This can be due to variable activities of patients, but can lead to a rate of distraction that is suboptimal, either too fast or slow [14, 15].
The PRECICE nail uses an externally applied magnetic device to control the lengthening. The proposed advantages to this include the ability to not only monitor the lengthening but also change the prescription of lengthening based on optimal conditions and the regenerate response time. There is less clinical evidence regarding this device but results appear similar to the ISKD with unique difficulties encountered [16, 17].
With respect to critical cortical defects and nonunion, these devices can be utilized for either compression of a fracture site or distraction osteogenesis. If a defect is predicted, this can be used to compress the fracture and then to perform an osteotomy and distract healthy bone to attain regenerate.
15.2.3 Distraction with Plate Osteosynthesis
The use of intramedullary nails in conjunction with external fixator distraction can be complicated by pin site infection that can develop into an intramedullary infection due to the proximity of the pins and the nail. It is also limited by the ability to apply transport to a proximal or distal fracture. Oh et al. [18] recently reported the use of locking plate stabilization with external fixator generated distraction osteogenesis. In their series of ten patients, a similar technique of corticotomy is performed, and after a latency period, distraction proceeded with 1 mm/day. When the docking site is achieved, the transport segment is stabilized with screw fixation through the plate, the docking site is grafted, and the external fixator is removed. All patients achieved radiographic union, and complications involve pin site infections only. Theoretically, these patients might be at higher risk for fracture of regenerate bone, although this has not occurred for them at the time of publication. The primary advantage is the ability to stabilize the transport segment and remove the external fixator despite a lack of radiographic union. The disadvantage is theoretically the lack of loadbearing the plate can contribute. However, the advantages of being able to apply this technique to skeletally immature patients, large amount of bone available for placement of external fixation, and decreased time to removal of external fixation can outweigh these disadvantages (Fig. 15.4).
Fig. 15.4
14-year-old male who underwent resection for osteosarcoma with limb foreshortening and flexion contracture of the knee. Distraction with plate osteosynthesis utilized with proximal tibial corticotomy highlighted (yellow arrow) to the left. External fixator removed at 7 weeks and consolidate locked into the plate construct distally. Allowed for 4.6 cm of distraction in 63 days of external fixation. Consolidation of regenerate noted to be complete by 4 months on the right. (Courtesy of Chang-Wug Oh, MD, Kyungpook National University Hospital, Daegu, Korea)
15.3 Masquelet Technique
The induced membrane technique is a unique alternative to acute bulk grafting. This technique was originally utilized for regeneration of diaphyseal defects, but use has been expanded to metaphyseal defects as well. Professor Masquelet developed the technique in early 1984 and soon after initiated a clinical study to demonstrate its efficacy [2] .
Key Features
A bioactive membrane is created by placement of a Poly(methyl methacrylate) (PMMA) block into a clean, debrided defect (Fig. 15.5).
Fig. 15.5
The forceps are holding the induced membrane which has been opened longitudinally and provides vascularized pouch for graft material
The blood supply around the induced membrane is left intact or optimized by free tissue transfer.
The induced membrane is incised, and the PMMA block is carefully removed, leaving the membrane intact as a protective and supportive grafting bed.
Slow consolidation is observed, and weight bearing is restricted until union [2].
15.3.1 Membrane
The induced membrane is believed to be a unique property of this technique and critical to its success. Extensive animal evaluations in both small and medium animal models have demonstrated the membrane is made of a type I collagen-heavy matrix and fibroblastic cells. The membrane itself has tissue level organization with an inner aspect of epithelial-like fibroblasts and collagen bundles that run parallel to the surface of the membrane. This tissue is well vascularized and contains a high concentration of vascular endothelial growth factor. Typically, a solid block of PMMA is used to produce the spacer; this induces a mild foreign-body inflammatory response with giant cells and macrophages. The inflammatory response slowly decreases over time following spacer implantation may disappear by 6 months following bone grafting. Tissue from these membranes has been analyzed using molecular techniques including immunohistochemistry, and these studies demonstrate expression of proteins associated with induction of new bone formation. Thus, many feel that these membranes are bioactive. In addition, the induced membrane also acts to eliminate soft tissue interposition into defects and created a protective cavity to accept bone graft. The shape and size of the healed bone graft are defined by the membrane [2, 19–22].
15.3.2 Technique
By definition, this is a two-stage technique. The first stage is akin to a tumor debridement with aggressive removal of nonviable bone, scar, and any damaged or nonviable local soft tissues. The bone debridement cannot be limited since frequently bone necrosis at the fracture edges has progressed significantly proximal to the defect. After debridement/resection, the remaining bone ends should be healthy with a viable bleeding bed (Fig. 15.6). In the setting of a severe soft tissue deficit or wound problem, standard dead space management techniques using PMMA bead strands can be used, while the preliminary wound management is performed. Open wounds can be managed with negative pressure therapy or bead pouch depending on the individual patient need. Once the soft tissue bed is clean and mature, the definitive solid spacer can be placed with simultaneous muscle coverage.
Fig. 15.6
Diaphyseal infection undergoes aggressive resection and debridement. a, b The defect is filled with PMMA, and preliminary stabilization is achieved with external fixation. c, d Classically, the ends of the bone are over wrapped with PMMA. At 8 weeks, the wound is filled with cancellous autograft and BMP and formal plate fixation is utilized. e, f At 6 months, the regenerate is completely healed and the patient is weight bearing
When feasible, intramedullary reaming is performed ot aid in the debridement of the intramedullary canal and to stimulate an endosteal healing response. For optimum membrane induction and better stability of the construct, the cement should be placed inside the canal (when feasible) and over the edges of the native bone (wrapping) and should fill the space of defect. While external fixation was utilized in the original technique, more stable forms of internal fixation are typically utilized, even intramedullary nails. Use of intramedullary nails can decrease required graft volumes and provide long-term stability in these slowly healing constructs. Finally, optimal soft tissue blood supply is requisite around the induced membrane zone. Free tissue transfer is far optimal to a tight primary wound closure especially in the mid-to-distal tibia.
15.3.3 Outcomes
The original Masquelet series of 35 patients with upper and lower extremity segmental defects that measured 4–25 cm in length reported a 100% healing rate. Most of these were treated with external fixation and many had free flaps. The mean time to full weight bearing was 8.5 months [23]. While this series is impressive, it likely does not represent contemporary use of the technique. Subsequent reports have included the use of bone morphogenetic protein (BMP) , reamed intramedullary grafts, and multiple modes of internal fixation—for most of these techniques, ultimate union rates hover around 90% [2, 24, 25]. While many of these publications report good results, overall the level of evidence for this technique remains low since these are mostly retrospective case series or small prospective noncomparative studies.
15.3.4 New Considerations
The timing of bone grafting into the membrane has been recently evaluated [26]. While contemporary approaches demonstrate large variability in timing of secondary cancellous grafting into the membrane bed, most surgeons delay 6 weeks or more after placement of the spacer. A closer evaluation of one of the original animal studies demonstrated the time course of growth factor expression from induced membrane samples with quantitative and qualitative immunohistochemistry [20]. Maximum BMP-2 levels were seen at 4 weeks post-procedure with decrease over subsequent weeks. These data may suggest that the optimal time of membrane bioactivity is earlier than suspected. Samples of human induced membrane tissue were assayed for multiple time points. One-month-old membrane samples had the highest expression of VEGF, IL-6, and Col-1, whereas two-month-old membranes expressed <40% of the levels of the one-month-old membranes [26]. This study suggests a time-dependent decrease in bioactivity of the membrane and may suggest a role for earlier secondary grafting. So in the absence of definitive evidence for specific timing, grafting can be safely performed as soon as the wounds have healed well without evidence of residual infection and systemic antibiotic therapy is near complete (4–6 weeks). There is likely little benefit to protracted delays (greater than 8 weeks) to secondary graft application.
15.4 Cage Technique
In 2002, Ostermann published the first reports of extending the indication for use of titanium mesh cages to restore bony continuity [27]. These devices are routinely utilized in spine surgery to augment the use of nonstructural allograft. They have demonstrated adequate ability to achieve bony union in conjunction with bone graft [28, 29]. The goal of utilizing the titanium cage is that cancellous allograft and demineralized bone matrix products offer advantages of no donor-site morbidity and ease of application. The difficulty in utilization of nonstructural allograft bone is that it does not reliably lead to bony union in gaps greater than 3 cm, those of critical cortical defects. The addition of the titanium mesh cage extends the application of the allograft material by imparting additional stability.
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