WORKUP	Section 5 of 11
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Lab Studies:

• The most critical step in the workup is to carefully review the patient's prior history, through evaluation of previous records, imaging studies, and discussion with the patient and previous treating physicians. Most often, the nonunion has occurred despite appropriate care, and rushing into treatment without a good understanding of why the nonunion occurred and how treatment will overcome these obstacles is a mistake.

• The role of the diagnostic workup is 3-fold. The first goal is to assess the patient to determine if he or she is able to undergo successful surgery. This obviously implies a routine preoperative assessment, but more specific laboratory tests may be indicated in an effort to determine if any systemic factors contribute to the failure of union. Laboratory assessment to determine the patient's nutritional status may be indicated. The total lymphocyte count and Rainey-Macdonald nutritional index may be helpful in identifying patients who may (or may not) develop infections after long bone fractures (Puskarich, 1990).

• The second goal is to assess for any signs of infection. Evaluation with a routine complete blood cell count (CBC), sedimentation rate, and C-reactive protein (CRP) may be helpful. The CRP is the most accurate indicator of infection (Chan, 2002), but it is not necessarily specific for infection. Cultures may be helpful, but findings are often negative, especially if the patient has been treated with antibiotics.

Imaging Studies:

• The third goal of the diagnostic workup is to assess fracture deformity. Plain radiography is typically the most helpful tool. The deformity must be assessed in both anteroposterior (AP) and lateral planes, with resolution of the plane and degree of maximum deformity. Any rotational component must be assessed either clinically or with CT scanning. Leg length equality should be determined clinically or more accurately with scanography. Finally, fracture stability must be determined. Often, the fracture nonunion is difficult to assess on plain radiography and fluoroscopy, CT scanning, or tomography may be helpful. Assessment of the fibula is important to determine that it is not preventing tibial union.

• MRI is probably the most sensitive and specific study for osteomyelitis (Mason, 1989), with an accuracy of over 90%. It also provides additional information regarding the anatomy and location of infected bone, sinus tracks, and sequestrums. Unfortunately, MRI is less effective if residual hardware is present, and other studies may be more appropriate. Technetium Tc-99m diphosphonate bone scanning has been used in an attempt to identify infections, but it is not specific for infection. However, combining this scan with Indium In-111–labeled leukocyte imaging increases the accuracy to 82% (Nepola, 1993).

Other Tests:

• Vascular studies may be indicated if prior injury is a concern or if a free soft tissue transfer is indicated. Consultation with a plastic surgeon may be warranted. Careful assessment and documentation of skin integrity and motor and sensory function are critical for surgical planning.

	TREATMENT	Section 6 of 11
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Medical therapy:

Nonoperative methods

Nonoperative methods should always be considered and, although rarely used as the definitive treatment, may be helpful as an adjunct treatment or as a temporizing option.

• Functional cast bracing may be considered for selective cases. In a 2003 study by Sarmiento, this treatment was unsuccessful in fewer than 10% of patients, although the majority of patients also had fibular osteotomies and/or bone grafting. This is especially common in patients at the extremes of age. Geriatric patients, especially those not fit for major surgery, can be successfully treated with a cast brace. Meticulous attention is required for the skin condition. Pediatric nonunions (not congenital pseudoarthrosis) generally result from open fractures with soft tissue stripping and bone devascularization. Functional cast bracing is an effective method for achieving union.

• Pulsed electromagnetic stimulation has been shown to be an effective modality, especially for hypertrophic nonunions (Brighton, 1995; Guerkov, 2001), but it does not address issues of instability, deformity, or leg length inequality.

• Low-frequency ultrasonography has been shown to decrease fracture healing time. A recent meta-analysis that reviewed 138 articles (of which only 6 met their rigorous inclusion criteria) reported that fracture healing was found to occur about 2 months sooner with the use of ultrasonography (Busse, 2002).

Surgical therapy:

Treatment principles and rationale

Hypertrophic nonunions show prolific callus formation. These vascular nonunions have excellent healing potential. They are best treated with rigid stabilization with or without compression. Additional biologic stimulation in the form of bone grafting is not required. Atrophic nonunions are characterized by an absence of callus, deficient bone vascularity, and poor healing potential. Debridement of all necrotic tissue is necessary, with opposition of viable and vascular bone fragments. In addition, biologic stimulation is required. Historically, this has taken the form of bone grafting, preferably autograft, which is osteogenic, osteoconductive, and osteoinductive. The posterolateral approach is usually preferred to the anterolateral approach because greater space is available for bone grafting and an additional incision through the previous scar is avoided. The posterolateral approach should not be used in proximal third tibial fractures because of the high risk of injury to the neurovascular structures.

Bone marrow injection has been shown to be an easy and effective treatment. This should be accomplished with the aid of fluoroscopy. Marrow is harvested from the iliac crest and injected directly into the posterior fracture site. In one study, 9 of 11 nonunions healed within 4-23 weeks, without further surgery (Sim, 1993).

The use of BMP and other osteoinductive agents has gained increased support experimentally and clinically (Vaccaro, 2002; Heckman, 1991). With high costs and limited clinical applications, indications are still being developed.

Surgical treatment

Principles of surgical treatment include the incorporation of the following:

• Fibular osteotomy

• Removal of ineffective, broken, or infected hardware

• Use of biologic bone enhancement, as described above

• Bone stabilization

• Eradication of infection

A fibular osteotomy should be used if the fibula is felt to be inhibiting compression across the tibial nonunion site. This is usually performed in combination with other procedures and is used as an isolated procedure only if a stable noninfected hypertrophic nonunion with little or no deformity is present. Usually a small segment of bone is removed (1-2 cm).

Removal of necrotic or infected bone must be performed for a union to occur. This may involve the need for significant bone graft, shortening, or bone transport.

Bony alignment and stability is essential for satisfactory treatment of a tibial nonunion. The use of a reamed intramedullary (IM) nail is an excellent method of treatment of noninfected nonunions, especially in the middle three fifths of the tibia (Wu, 1999). Conversion from a nonreamed nail or plate in closed and grade I or II open fractures with no evidence of infection is the primary indication. This technique has the advantage of early rehabilitation and maintenance of the alignment, and the reaming may act as a bone graft at the fracture site. For patients with a history of infection, previous external fixation, very proximal or distal fractures, or significant malalignment, this technique is less effective. This technique can also be difficult, and the surgeon must be experienced with IM nailing techniques. The use of end reaming (cutting) bits, fluoroscopy, and a femoral IM distracter may be helpful.

Compression plating has also been shown to be effective for treating tibial nonunions. Wiss treated 49 patients with a tibial nonunion after initial external fixation (Wiss, 1992). The patients demonstrated a 92% healing rate in a mean of 7 months with no further treatment. Compression plating has the advantage of being applied anywhere along the tibia, and casting is usually unnecessary. However, it may contribute to difficulties with wound healing and can potentially devascularize a segment of bone. Handle the soft tissues in an atraumatic manner. Keep dissection and periosteal stripping to a minimum. Additionally, in patients with poor bone quality, the fixation is less secure. Recently, the use of a locking custom blade plate for periarticular nonunions has been described (Harvey, 2003).

The use of external fixation, especially small wire and hybrid external fixation, is an excellent option for the treatment of tibial nonunions, especially if the fracture is very proximal or distal (periarticular), if significant bone loss occurred, if deformity (including shortening) is significant, or if ongoing infection is present. The use of external fixation allows for the treatment of multiple issues concurrently. External fixation can provide for stability of the fracture site, even in very proximal or distal fractures, with the use of fine wire fixation. Large infected bone segments can be removed and grafted, or a shortening can be performed.

Limb length equalization can be performed with bone transport or as an isolated procedure after union has occurred. Adjunct therapy, such as the use of antibiotic bone cement or bone substitute beads, can easily be incorporated, and stabilization with external fixation usually provides for access if soft tissue grafts are needed. The use of external fixation is probably the best technique for patients with complex and significant angular deformities that require correction and are too great for acute correction. Although highly versatile, pin site infections occur routinely, making subsequent conversion to an IM nail difficult. Specialized training or experience in these techniques is important.