Distal Tibia and Ankle Nonunions



Fig. 14.1
13-year-old girl hit by a light pole while waiting for the school bus. a, b Anteroposterior (AP) and lateral of the hypertrophic nonunion with deformity. c Application of a multiplanar external fixator to add stability, no fracture exposure, deformity correction. d, e AP and lateral of fracture union after frame removal



Ilizarov described nonunions as stiff or mobile [1113]. Stiff nonunions, those with less than 7 degrees of motion at the fracture site, are thought to be biologically viable and thus equivalent to the hypertrophic nonunion. They require stability to heal, are biologically viable, and can be a source of new bone formation if distracted. In many instances, they can be treated closed. Lax nonunions have more than 7 degrees of motion and are equivalent to the atrophic nonunion of Weber. They not only require stability to heal, but also require open debridement of the nonunion site to stimulate the bone and the addition of bone graft or other biological stimulus. They are not a source of new bone with pure distraction, but instead require compression.

The evaluation of the patient with a nonunion, just as with an acute injury, requires a thorough look at more than just the fracture pattern and the radiographs. One must determine the “personality of the fracture,” as coined by Schatzker and Tile [14]. This involves a complete history of the events of the injury, the fracture, the host, the treating physician, and the institution at which the treatment will occur. Only with this kind of analysis can one do proper preoperative planning and optimize the chance for success.



14.5 Clinical Evaluation


A comprehensive history is essential, as a complete picture of the fracture and the host must be obtained. Was the initial injury open or closed? Was there a high-energy mechanism such as a motorcycle accident or a lower energy trip and fall? Were there any neurovascular issues at the time of initial injury or after treatment? A determination of the type and number of previous surgeries is essential, as is the presence and treatment of previous infection. If there is retained hardware at the fracture, old operative notes can be helpful in identifying the hardware type and manufacturer for planned removal. Have previous fractures healed in a timely fashion? Patients with recreational drug habits or other substance abuse may have compliance issues. Smokers are at risk because of the well-documented relationship between nicotine use and delayed healing. Patients using nicotine gum are not immune to this problem. The occupation of the patient is important, as treatment that requires a non-weight bearing gait will cause a longer period off work for a laborer than for a patient with a more sedentary occupation. The knowledge of the avocations and hobbies of your patient are also important, as it rounds out the level of activity to which the patient must return. Hospital discharge planning often begins before surgery. The patient’s living situation, amount of support from family or friends, their financial resources, the location of their home, and what type of dwelling in which they reside is helpful in planning successful aftercare.

A thorough musculoskeletal examination is also mandatory. Examination of the patient’s other extremities will provide clues as to other disabilities that may play a role in mobility and later rehabilitation. Examination of the non-united segment includes an inspection for gross deformity and overall limb alignment. Gross limb length can be checked, and if the patient is ambulatory, the gait pattern should be examined. The fracture site should be checked for pain to manual stress, as well as the presence of gross or subtle motion. The stability and motion of adjacent joints should be examined. Ligamentous instability may require reconstruction as part of the treatment plan. If there is joint contracture or subluxation present, it should be determined if it is due to soft tissue contracture, heterotopic ossification, joint ankylosis, or a combination of factors.

The skin should be inspected for the presence, location, and healing status of previous open wounds and incisions. Adherent skin, especially in areas with subcutaneous bone such as the medial face of the tibia, the distal fibula, and the calcaneus, can be an obstacle. The presence or absence of lymphedema or venous stasis should be noted, as it may influence the choice of surgical approach. If previous external fixators have been in place, the condition of the old pin sites should be examined for signs of previous infection. A complete neurovascular examination should be carried out. Patients with suspected dysvascular limbs should be sent for more thorough testing, including transcutaneous oxygen tension and ankle-brachial indices. Existing nerve deficits can be examined tested by electromyography to determine the likelihood of recovery.

Radiographic evaluation includes true anteroposterior and lateral films of the problem limb segment, orthogonal to the “normal” portion of the limb. Radiographic signs of a nonunion can be subtle but include the absence of bridging trabeculae, sclerotic fracture edges, persistent fracture lines, and broken or displaced hardware. If deformity or limb length issues are suspected, additional work-up is required. Standard full-length alignment films should be obtained, as well as alignment films centered on each area in question, i.e., tibia or ankle. Deformities must be fully characterized in all six axes so that correction can be planned. Comparison films of the contralateral leg are helpful in determining the normal alignment of the patient, and population normals can be used if the problem is bilateral. Computed tomography scans with reconstructions can be helpful in analyzing subtle nonunions, but can be hard to interpret with fracture fixation devices in place. Plain tomography can be very helpful in these instances, but is increasingly unavailable. If infection is suspected, a combined bone scan and tagged white cell study can help differentiate bone turnover from active infection. Magnetic resonance imaging can be helpful in evaluating a bone for infection, or looking at ligaments in adjacent joints, but are not commonly used in the evaluation of nonunions.

Laboratory studies can round out the clinical picture of the patient. In addition to routine preoperative chemistries and blood counts, patients suspected of infection should have their erythrocyte sedimentation rate and C-reactive protein checked. Patients suspected of malnutrition should have a complete nutritional panel drawn, including liver enzymes, total protein and albumin levels, and calcium, phosphate and vitamin D levels.

The last part of developing the “personality of the fracture” is a critical self-examination of the surgeon and the treating facility. Surgeons should honestly examine whether they have the training, skill, patience, and experience necessary to treat a complex nonunion. Even the most gifted surgeon requires help, and the appropriate consultants must be available from plastic and vascular surgery, internal medicine, and infectious disease. The hospital is the final element. Is the correct equipment in the house or available to be brought in? Is experienced nursing and surgical assistance available? Can the anesthesia staff care for the needs of the patient?

At the end of the evaluation, the surgeon should create a complete problem list in anticipation of preoperative planning [15]. An attempt should be made to define the cause of the nonunion and reverse it. Soft tissue defects, either existing or anticipated, must be covered. The consults required should be listed and obtained. Infected nonunions require debridement, temporary stabilization, and conversion to a non-infected nonunion, with eventual staged reconstruction. Constructs with mechanical instability should be made stable; those with a gap require strategies to restore bone loss; those with deformity require a better reduction or length; and those with vascularity require a better soft tissue environment and biological stimulation.

Using this problem list, a detailed preoperative plan should be drawn out in detail in all but the simplest of conditions. Putting the case on paper, often with multiple methods or implants, allows one to foresee possible obstacles to success, to define the sequential steps in the operation, to select the appropriate patient positioning as well as to ensure the availability of equipment and implants, and to make the procedure in the operating room the execution of a plan instead of a surgical adventure (Tables 14.1 and 14.2).


Table 14.1
Treatment suggestions: distal tibia and ankle nonunions




















































Classification

Objective

Treatment

Suggestions

Problems

Hypertrophic

nonunion

Provide stability

Plate, external fixation, nail with polar screws

Does not require grafting

Must provide adequate stability

Atrophic/oligotrophic nonunion

Provide stability and biological stimulus

Bone graft or appropriate substitute, stable fixation

Thorough debridement or excision of nonunion

Failure to provide biology and stability

Nonunion with deformity

Treat nonunion and deformity

Deformity correction, stability and biology

Formal deformity analysis

Failure to restore mechanical axis

Metaphyseal nonunion

Maintain axial alignment

Plate, external fixation, nail with polar screws

Provide adequate fixation, build external fixator to foot if needed

Prevention of deformity

Malleolar nonunion

Restore joint stability

AO techniques

Restore ankle mortise, stress views in OR

Failure to restore joint stability

Articular nonunion

Restore articular surface

Rigid internal fixation

Arthrodesis if surface is not reconstructable

Cartilage injury, poor prognosis



Table 14.2
Treatment strategy: distal tibia and ankle nonunions

























Treatment method

Clinical indication

Plate and screw fixation

Metaphyseal, malleolar, or articular nonunion, no infection, adequate soft tissue

Intramedullary nail

Metaphyseal location, may require polar screws for stability, no infection

Multiplanar external fixation

Larger deformity, leg length deficiency, infection, bone defect, poor soft tissue, joint subluxation

Acute correction

Small or no deformity, no lengthening, adequate soft tissues, nonunion requires open approach

Gradual correction

Larger deformity, leg length deficiency, infection, bone defect, poor soft tissue, joint subluxation

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Jan 24, 2018 | Posted by in ORTHOPEDIC | Comments Off on Distal Tibia and Ankle Nonunions

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