Delayed Union and Nonunion of Fractures

Status of soft tissues and Neurovascular structures

The condition of the soft tissues surrounding a nonunion must be considered in treatment planning. Significant soft-tissue scarring, especially on the concave side of a deformity, may result in skin necrosis requiring aggressive correction. Scarring also may limit some treatment options or require treatment of the nonunion with concomitant free-tissue transfer. Soft-tissue contractures must be considered if treatment of the nonunion would result in lengthening of the extremity.

In patients with histories of vascular injuries or patients with weak or absent peripheral pulses, an arteriogram may be indicated to evaluate vascular status. A significant vascular abnormality may limit treatment methods and fracture healing. Vascular abnormalities should be corrected, if possible.

Any nerve deficit should be carefully considered. In patients with long-standing significant deformity, Ilizarov or Taylor Spatial Frame (Smith & Nephew, Memphis, TN) treatment may be most appropriate for gradual deformity correction or lengthening of the nonunion. When the nerves are so damaged that sensation and motor function in a lower extremity are permanently lost, amputation usually is the more practical choice.

Status of bones

The status of the bones, especially at the nonunion, depends on the type and duration of the fracture and the method of any previous treatment. Nonunions are classified based on location, presence or absence of infection, and etiology:

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  Epiphyseal, metaphyseal, or diaphyseal

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  Septic or aseptic

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  Hypertrophic, oligotrophic, or atrophic ( Fig. 59.3 )

  

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  Pseudarthrosis

Septic nonunions are much more difficult to treat than aseptic nonunions. Hypertrophic nonunions ( Fig. 59.4 ) have adequate vascularity, display abundant callus, and lack stability. Oligotrophic nonunions usually have adequate vascularity, display little or no callus, and often are associated with malreduction (distraction). Atrophic nonunions ( Fig. 59.5 ) lack adequate vascularity and display no callus. Synovial pseudarthrosis ( Fig. 59.6 ) involves sealed medullary canals with an associated pseudomembrane containing fluid. Radiographic appearance is variable, and technetium bone scan reveals a “cold cleft” between areas of increased activity. Classification of nonunions has historically guided treatment and is therefore important to understand.

Many options are available for treatment of nonunions, including invasive and noninvasive modalities. Noninvasive interventions include casting or bracing, low-intensity pulsed ultrasound (LIPUS), electric or electromagnetic stimulation, and extracorporeal shock-wave therapy. Invasive interventions include bone grafting (or bone grafting alternatives) and stabilization. Stabilization can take many forms but primarily involves plating, intramedullary nailing, or external fixation. To treat nonunions most effectively, a surgeon should have some experience with all forms of surgical stabilization.

Often a nonunion may be treated with several different interventions. The patient should be involved in the discussion because potential risks and benefits vary among treatments. When selecting treatment, thought should be given to future interventions that may be necessary if the fracture does not unite. Operations for nonunions are relatively invasive and should be undertaken only after nonunion has been proven clinically and radiographically or when union is extremely unlikely or impossible without a change in current treatment.

The requirements for successful nonunion treatment are biomechanical stability and a biologic vitality of the bone. These requirements can be obtained through reduction of fragments, bone grafting, and stabilization of the fragments. Many techniques or combinations of techniques meet these requirements, and some general guidelines apply to all techniques.

Plating

Plating ( Fig. 59.11 ) in the treatment of nonunions, as in acute fractures, should provide sufficient stability for fracture healing. The plating technique and choice of plate depend on the type of nonunion, the condition of the soft tissues and bone, the size and position of the bone fragments, and the size of the bony defect. Plating without bone grafting usually is adequate for hypertrophic nonunions if the bone is not osteoporotic and the fragments are large enough for secure screw fixation. Plating typically is performed with a compression technique, but it may be performed with a neutralization technique if lag screws were successfully placed across the nonunion. Bridge plating or wave plating also can be used.

Intramedullary nailing

Intramedullary nailing is very useful in nonunions of long bones, such as the tibia or femur ( Fig. 59.12 ). However, intramedullary nailing, particularly exchange nailing, is not the best option for humeral nonunion. If alignment is acceptable or closed reduction can be obtained, the procedure can be performed without opening the fracture site. Bone grafting usually is not required. If necessary, long bone intramedullary reaming can generate a large amount of corticocancellous graft material that can be easily harvested with a RIA system with little increased morbidity. When an open technique is required, usually only limited exposure and dissection are required. Early weight bearing is possible, and the effects of prolonged non–weight bearing may be minimized. A relative contraindication for intramedullary nailing is current infection; however, intramedullary nailing can be successful for infected nonunions once the infection has been eradicated.

A newer type of intramedullary nail, a magnetic compression nail (Precise, NuVasive, San Diego, CA), is being used with increasing frequency in the treatment of nonunions. This nail allows sustained compression at the nonunion site. Early results from this device have been positive in the treatment of humeral, tibial, and femoral nonunions. As with many new devices, comparative studies with standard treatments evaluating clinical results and cost implications have not yet been published.

External fixation

Circular fine wire fixation, such as the Ilizarov fixator, is a labor-intensive, but very effective, tool in the treatment of nonunions. It is especially useful in nonunions associated with infection, osseous defects, and deformity. The Taylor Spatial Frame is a more contemporary circular fine-wire fixator that relies on computer software to assist in deformity correction ( Fig. 59.13 ). An advantage of external fixation is that it is relatively noninvasive and does not disturb soft tissues surrounding the nonunion. Other advantages are its ability to correct deformity and provide stable fixation. Similar to intramedullary nailing, early weight bearing is possible, and the effects of prolonged non–weight bearing may be minimized.

Conventional treatment

The objectives of the conventional method are to convert an infected and draining nonunion into one that has not drained for several months and to promote healing of the nonunion by bone grafting. This method of treatment often requires a prolonged period of time and many potential operations. Debridement is performed with removal of all foreign, infected, or devitalized materials to provide a vascular bed. Providing some element of stabilization is considered at this point with appropriate coverage provided by the plastic surgery team. Infections can be controlled more easily when robust, highly vascular soft tissue is used to cover the fracture, especially with infected nonunions of the tibia. External fixation may initially be most appropriate. Antibiotics are used systemically and are based on intraoperative cultures. Bone grafting is deferred until the soft tissues have completely healed and become stabilized. In some patients, the fracture may unite and bone grafting becomes unnecessary.

When the clinical signs of infection have subsided, the soft tissues over the bone are good, and when nonunion persists, bone grafting is considered. There may never be a perfect time to graft the nonunion because whether an infection has been completely eradicated or is merely quiescent cannot be determined for sure, but a time must be selected or conventional treatment abandoned. The character and duration of the infection, the time of the last drainage, and the general condition of the extremity all must be considered.

When an infection has been active chiefly in the soft tissues or around sequestra, the risk of reactivating it by surgery is much less than when it has involved the cortex and medullary canal. When the infection has been prolonged and destructive, all the surrounding structures are presumed to have been deeply penetrated, and a dormant infection is likely. Bacteria can lie dormant for years, only to become active again after surgery or some other trauma. This danger is inherent in the treatment of infected nonunions and must be accepted. The use of antibiotics before and after surgery has reduced the danger because they can often control an infection within the limits of a vascular area, but they cannot be expected to sterilize an avascular area that they cannot penetrate. Reconstructive operations usually should be delayed until at least 6 months after all signs of infection have disappeared.

Controlling infection before attempting bone grafting always has been a sound clinical principle in the conventional treatment of nonunions. There are exceptions to this principle, however, especially in the tibia. Successful bone grafting in tibial nonunions, even in the presence of draining sinuses, has been reported. In sequestration or gross infection, the bone is saucerized through an anterior approach, the incision is closed or the wound is covered, and the infection is treated with antibiotics.

In treating the tibial nonunion itself, the anterior aspect of the tibia is avoided because the draining sinuses and poor skin usually are located here. The tibia is traditionally approached posterolaterally. The posterior aspect of the tibia (or the tibia and fibula) is decorticated proximal and distal to the nonunion. The entire area is grafted with autogenous cancellous iliac crest. The nonunion itself is not exposed; it is hoped that the grafted area will not communicate directly with the infected area.

Active treatment

The objective of the active method is to obtain bony union early and shorten the period of convalescence and preserve motion in the adjacent joints. Judet and Patel and Weber and Cech described this method, and much of the following is taken from their reports.

The first step is restoration of bony continuity. This takes absolute priority over treatment of the infection. The nonunion is exposed through the old scar and sinuses. The ends of the fragments are decorticated subperiosteally, forming many small osteoperiosteal fragments; any grafts that become detached are discarded. Next, all devitalized and infected bone and soft tissues are removed. Then the fragments are aligned and stabilized, usually by an external fixation device. Compression is applied across the nonunion if possible. Autogenous cancellous bone grafts can be inserted. Internal fixation with a plate is used only when drainage has ceased, and then the approach is away from the area of old drainage, or when no other method of fixation is possible and the infection is mild. When the fracture already has been firmly fixed with a plate or intramedullary nail, the fixation is not disturbed, and the operation is done as described except decortication is omitted when an intramedullary nail has been used. The wound is then closed, and systemic antibiotics are administered based on intraoperative cultures.

If necessary for union, a second decortication with or without the addition of autogenous cancellous graft is performed. After the nonunion has healed, any residual sequestra are removed, and split-thickness skin grafts are applied to any remaining defect in the skin. Satisfactory results have been reported with this method of treatment with or without cancellous grafts, with success rates ranging from 83% to 98%.

Polymethyl methacrylate antibiotic Beads

Antibiotic-impregnated polymethyl methacrylate (PMMA) beads can be used to treat infected nonunions. Thonse and Conway found that Palacos (Zimmer, Warsaw, IN) cement was superior in elution to Simplex (Stryker, Mahwah, NJ). Heat-stable antibiotics, such as tobramycin and gentamicin, can be mixed with PMMA and used locally to achieve 200 times the antibiotic concentration achieved with intravenous administration. The use of antibiotic-impregnated PMMA beads in conjunction with debridement in the management of infected nonunions was shown in one study to be more effective in treatment than systemic antibiotics. Placement of a PMMA spacer is another option that has the ability to provide some stability in an osseous defect situation. The body’s reaction to PMMA beads or a spacer leaves a bioactive membrane, Masquelet membrane ( Fig. 59.16 ). The use of cancellous bone graft to deliver antibiotics to infected nonunion sites has been described in a limited number of patients with satisfactory results; however, the optimal ratio of antibiotic to cancellous graft is not known.

Ilizarov method

According to Ilizarov, to eliminate infection and obtain union, vascularity must be increased. Three basic modes of application exist for the Ilizarov frame: (1) monofocal, (2) bifocal, and (3) trifocal ( Box 59.1 ). The Ilizarov frame allows multiple modes of treatment, including compression, distraction, lengthening, and bone transport. In the Ilizarov approach, vascularity is increased by corticotomy and application of a circular external fixator. Although infected nonunions frequently have been successfully treated without debridement, some authors recommend open debridement to remove necrotic and infected segments, followed by bone transport into the region and soft-tissue coverage. One study advocated segmental excision of the nonunion site followed by distraction osteogenesis. Catagni recommended compression for hypertrophic nonunions with minimal infection and no sequestered bone to increase formation of repair callus and vascularity. Monofocal compression also can be used for infected hypertrophic nonunions with deformity. For atrophic nonunions with diffuse infection or sequestered bone, open resection of the infected segment is performed and bifocal compression is used. If skin quality is poor, the bone is stabilized with the external fixator after resection of necrotic bone. When skin conditions improve and the infection has regressed, corticotomy is performed and bifocal compression ( Fig. 59.17 ) is applied.

Combinations of several of the methods described for infection can be used for treatment of the separate components of a complex nonunion, but the Ilizarov method allows simultaneous treatment of all components, including angular, rotary, and translational deformities; shortening; and segmental bone loss. Although dramatic results can be obtained, this method is technically demanding and requires thorough training and experience. It is recommended that only surgeons knowledgeable in its biologic basis and the techniques required for its safe, effective application use this method.

Deformities of 10 or 15 degrees can be corrected immediately by frame application; larger deformities should be corrected gradually. Hypertrophic nonunions can be treated by gradual correction of the deformity, followed by compression. Atrophic nonunions with shortening can be treated by compression at the nonunion accompanied by a corticotomy in the metaphyseal region of the same bone and gradual lengthening through the corticotomy. Ilizarov showed marked hypervascularity of the limb and bone after corticotomy and gradual distraction. Conceivably, the corticotomy provides some of the same biologic benefits as a bone graft. Nonunions with segmental bone loss can be treated by corticotomy and gradual transport of a fragment. The leading edge of this transported fragment frequently requires bone grafting at the time of arrival to the principal fragment. Depending on the size of the defect and the anticipated time to docking, bone grafting can be performed at the time of frame application or just before docking if necessary.

The sequence of correction of complex deformities, including shortening, rotation, angulation, translation, or a combination of one or more, varies, but generally length must be reestablished before other deformities can be corrected. It sometimes is difficult to evaluate malrotation when major angulation and translation deformities are present, and its correction may be best left until last. If rotation is corrected last, the frame must be mounted carefully, with the bone centered within the frame; otherwise, translation of one bone fragment would occur during final rotation and would require an additional step of translation to reestablish full apposition. Some complex deformities can be resolved with a simple hinge, and some simple deformities can be best treated with more complex constructs. The maximal velocity of bone or soft-tissue elongation is approximately 1 mm every 24 hours. During the correction of a complex deformity, the structures being lengthened most may change during the treatment, and the structure at greatest risk during any phase of treatment must be appreciated and monitored.

The Ilizarov frame can be constructed to provide compression or distraction or both, and careful preoperative evaluation of deformities allows assembly of the proper frame before surgery. True anteroposterior and lateral views of the limb are necessary. The importance of these orthogonal views cannot be overemphasized because these films are used to characterize completely the plane and extent of angulation and translational deformities and, along with preoperative sizing of the limb, to determine correct ring diameter to allow frame construction before surgery. First, the plane and the extent of deformity in this plane are determined. Next, the type of hinge or linkage frame necessary to correct the deformity (e.g., opening wedge or distraction hinge) is determined. Finally, the exact locations of the hinges or linkages are determined.

Taylor spatial frame method

The more contemporary Taylor Spatial Frame fine-wire external fixator has simplified deformity correction through utilization of a computer program. The computer program and virtual hinge assists with determining the exact position of wires or pins, hinges, and linkages in the correction of complex deformities. Struts can be manipulated daily by patients until deformity is corrected. This fixator is especially useful in treating hypertrophic nonunions and nonunions associated with infection, soft-tissue compromise, bone loss, and leg-length discrepancy. Several authors have reported its successful use in infected and noninfected nonunions. Application of the spatial frame is described in Chapter 54 .

Corticotomy

To lengthen a bone, a special type of percutaneous osteotomy, or corticotomy, is required ( Fig. 59.18 ). Paley et al. described an effective method of corticotomy in which a 5 mm osteotome is used to cut the medial and lateral cortices, extending subperiosteally into the posteromedial and posterolateral corners. The osteotome is turned 90 degrees to wedge open the incomplete osteotomy and to crack the remaining posterior cortex. This maneuver is repeated with the osteotome in the posteromedial and posterolateral cortices. The fixator rings above and below can be rotated to complete the osteoclasis. The corticotomy preserves the soft tissue inside and outside the bone (the periosteal and endosteal circulation). On a radiograph, the corticotomy should appear as a nondisplaced osteotomy.

Medial malleolus

A fracture of the medial malleolus occasionally fails to unite, usually after closed treatment. Surgery may be indicated for the few nonunions in which other serious complications of the fracture, such as posttraumatic arthrosis, are not seen on radiographs. The technique usually includes excision of the nonunion, application of autogenous bone grafts, and internal fixation of the malleolar fragment. When the nonunion is painful, it can be surgically managed in the following ways. When the bone adjacent to the nonunion is sclerotic or has been absorbed, and the proximal part of the malleolus is large enough to preserve the ankle mortise, resecting the ununited distal fragment is preferable to bone grafting ( Fig. 59.19 ). When the fragment is larger, bone grafting and stabilization usually are indicated. Bicortical lag screws probably are indicated; they have been shown to be more stable and less likely to be associated with nonunion.