George J. Haidukewych
Fractures and ligament injuries around the knee joint are among the most common orthopaedic injuries encountered. Although contemporary methods of ligament reconstruction and open reduction and internal fixation (ORIF) can result in excellent long-term outcomes, occasionally posttraumatic arthritis can result. Reconstructive options include some form of osteotomy, arthrodesis, or arthroplasty. Challenges include stiffness, scarring, bony defects, malalignment, presence of extensive (often broken) hardware, and compromised soft tissues, Reconstructive decision making is based on patient age, activity, and the anatomic location and extent of damage to the articular surface. This chapter reviews reconstructive options for patients with posttraumatic arthritis of the knee.
Diagnosis
The specifics of preoperative evaluation vary based on whether the prior injury involved fracture of the distal femur, proximal tibia, or patella or was purely ligamentous. Some guiding principles, however, are common to all such evaluations. First and foremost, careful evaluation of the patient's complaints is important. The location and quality of pain, gait disturbance, and deformity should be ascertained. Preoperative range of motion (ROM) should be documented, as multiple studies have demonstrated that postoperative ROM correlates with preoperative ROM. These knees can be quite stiff from posttraumatic arthrosis and multiple prior operations.
The location of prior scars, skin grafts, and flaps should be evaluated. The status of the extensor mechanism, any contractures, and the status of the collateral ligaments should be documented. The neurovascular status of the limb should be carefully evaluated and documented.
Radiographic Evaluation
High-quality anteroposterior, lateral, and Merchant views are necessary to evaluate alignment, bony deficiency, location of hardware, and anatomic location of degenerative change. Long-standing so-called hip-to-ankle radiographs can assist the surgeon in evaluating angulatory deformity.
Occasionally there will be uncertainty regarding the status of a fracture union. In this situation, conventional or computed tomography can assist in evaluation of healing status.
Preoperative Workup
Preoperative medical optimization is recommended, including cessation of tobacco use, if possible. With a history of an open fracture or failed internal fixation, a complete blood count (CBC) with differential, sedimentation rate, and C-reactive protein should be obtained if there is any suspicion of infection. Aspiration of the knee may provide useful information in selected cases.
Treatment
The most difficult aspect of posttraumatic reconstruction around the knee is choosing the right operation for the patient. In most instances arthroplasty is chosen; occasionally the decision making is more complex (Fig. 19-1). Consider, for example, a 30-year-old overweight laborer with painful tricompartmental disease after an open knee dislocation with a prior vascular repair and free flap with current range of motion of 30 to 60 degrees. Although treatment should be individualized after a thorough discussion of various options with the patient, some general principles should be followed.
Typically, older, lower-demand patients are managed with arthroplasty and younger, more active patients are offered osteotomy or arthrodesis. In general, younger patients with single-compartment degenerative change and angular malalignment are selected for corrective osteotomy. Patient expectations, age, activity, and status of the articular
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surface all guide decision making. The author has found that most patients are not willing to accept an arthrodesis.
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Figure 19-1 A: Posttraumatic degenerative joint disease (DJD) after tibial plateau fracture. B: Treated with total knee arthroplasty. |
The principles of osteotomy and arthrodesis are covered elsewhere in this text. Therefore, we will focus on the specific technical considerations for arthroplasty in this setting.
Total Knee Arthroplasty for Posttraumatic Degenerative Joint Disease
Dealing with Hardware
There is tremendous variability in the internal fixation implants used to treat fractures about the knee. Typically it is wise to remove hardware that is symptomatic or that will interfere with the arthroplasty. In certain situations, it may be preferable to remove only a portion of the hardware. For example, a long lateral plate on the tibia may be left in situ, simply removing the proximal screws that interfere with tibial tray implantation. This avoids the need for extensive soft tissue dissection and avoids the need to bypass multiple stress risers distally in the tibial shaft. These can be sites of cement extravasation or postoperative fracture. In situations where extensive hardware must be removed, especially through multiple incisions, it may be best to remove the hardware in a first operation, then perform the definitive reconstruction after the soft tissue has recovered. When infection is a concern, the reconstruction should be staged. The author prefers to remove hardware only if it precludes performance of the arthroplasty or if it is symptomatic.
Dealing with Skin Issues
Many patients in this setting will have an incision in a nonideal location for total knee arthroplasty (TKA). Typically the most recent or most lateral incision should be chosen that avoids the elevation of a large subcutaneous flap. A preoperative consultation with a plastic surgeon may be helpful in more complex cases. In some cases, especially those with prior skin grafts or very adherent skin over the patellar tendon or tibial tubercle, one may consider preparatory gastrocnemius flap coverage prior to arthroplasty. The TKA is then planned after flap maturation and soft tissue recovery. This may avoid a situation in which a flap is required after skin breakdown with the prosthesis already implanted.
Exposure Problems
Stiffness is common in knees with posttraumatic arthritis, and it makes exposure more difficult. General principles for safe exposure include careful protection of the patellar tendon with sequential release of scarring in the suprapatellar area, gutters, and peritendinous tissue. The so-called quadriceps snip can be a useful technique. The author prefers to perform an arthrotomy gradually traversing the quadriceps tendon and extending laterally into the vastus lateralis musculature. This leaves a long area of tissue for subsequent repair. Combined external
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rotation of the tibia, resection of the cruciate ligaments, and a proximal medial tibial “peel” is generally adequate. Patellar subluxation, rather than eversion, may be preferred. These typical exposure techniques are commonly used during revision arthroplasty and are covered in greater detail elsewhere in this text. The author prefers to avoid the so-called quadriceps turn down and tibial tubercle osteotomies when possible. The turn down may devascularize the tendon and patella, and the tubercle fragment may be difficult to reattach with a previously fractured tibia.
Dealing with Deformity (Malunion, Nonunion)
Angular malunion is rare with contemporary open reduction and internal fixation (ORIF) techniques and implants. However, occasionally the patient may present with a malunion that makes traditional TKA difficult or impossible. Long-standing hip-to-ankle radiographs are essential. By templating the amount of bone resection necessary to achieve a normal limb axis and horizontal joint line, the surgeon can determine whether corrective osteotomy should be performed prior to arthroplasty (Figs. 19-2A, B). If excessive bone would need to be resected to perform the arthroplasty (for example, the distal femoral resection would compromise a collateral ligament), the malunion should be corrected prior to TKA. Although rare, rotational malunion can occur, typically of the distal femur. A CT scan, including cuts through both femoral necks and both distal femoral epicondyles, can quantify the rotational deformity preoperatively. Because component rotation affects patellar tracking and long-term performance of the arthroplasty, malunions such as malrotations may be corrected prior to surgery. The author has found retrograde nailing after intramedullary osteotomy and derotation useful in this setting. This allows visualization of the epicondylar axis and simplifies hardware removal during later arthroplasty. Angular deformity of the femur and tibia are also effectively managed by oblique osteotomy and plating, especially if translation of the medullary canals precludes nailing techniques. Performing a TKA even in the case of a minor malunion can be challenging, and extra medullary alignment guides are often needed (Fig. 19-2). Alternatively, computer-assisted navigation systems may be considered when conventional jigs cannot be reliably applied. A comprehensive discussion of deformity correction about the knee is beyond the scope of this chapter.
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Figure 19-2 Total knee arthroplasty after distal femur malunion, anteroposterior (A) and lateral (B) views. |
Dealing with Nonunions
In general, in the nonunion setting, the decision regarding TKA versus revision ORIF is based on patient age, status of the articular surface, and remaining articular bone stock. Nonunions of fractures of the proximal tibia are rare. If they occur, the options include revision ORIF and bone graft, or a TKA. No large series of TKA performed in this setting has been reported. Some have recommended bypassing the nonunion with a long stem and bone grafting the nonunion with autologous bone from the bony cuts.
Nonunions of distal femur fractures pose greater challenges and are more common. Usually it is preferable to obtain fracture union with revision ORIF if sufficient bone stock remains distally. Some authors have recommended TKA with intramedullary fixation of the nonunion using the cut bony fragments as autograft. Kress et al. reported a series of nine patients treated for periarticular nonunions with TKA and stems with excellent results. Haidukewych et al. reported a series of 17 patients undergoing TKA for failed ORIF or nonunion of the distal femur. Two of three patients treated with TKA with intramedullary stem stabilization of the nonunion healed. Anderson et al. achieved successful union in ten patients with long-stem fixation and autograft. These limited series document that TKA with stem fixation used to “nail” the nonunion can be effective in selected cases.
In older, lower-demand patients with inadequate distal bone stock for conventional arthroplasty or revision ORIF, the use of distal femoral replacements, so-called tumor
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prostheses may be the most predictable option (Fig. 19-3). These offer the advantage of immediate weight bearing for the typically elderly population undergoing these surgeries. Cemented fixation in this setting allows secure initial component fixation in diaphyses that are typically capacious and osteopenic.
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Figure 19-3 A, B: Multiply operated distal femoral nonunion with posttraumatic degenerative joint disease treated with a distal femoral replacement. |
Dealing with Bony Deficiency
The techniques for dealing with bony deficiency in the posttraumatic setting are similar to those used during revision arthroplasty. Generally, defects are managed incrementally with techniques such as cement fill, cement and screws, metal augmentation with wedges or cones, or structural allograft as the defect size increases. Large cavitary deficiencies are rare in this setting but, if present, can be managed with commercially available metal metaphyseal cones or impaction bone grafting techniques.
The liberal use of stems should be encouraged to bypass stress risers and unload deficient periarticular bone. In general, if a metal augment is used, a stem should be used as well. Cemented and cementless stems can be used effectively, and there are advantages and disadvantages to each choice. If a long diaphyseal engaging stem is necessary (for example, to bypass empty screw holes after plate removal), cementless stems are generally preferred. Cement is used on the cut bony surfaces and exposed metaphysis, but the diaphyseal fixation is uncemented. Recent data on the use of this so-called hybrid stem fixation technique documented excellent results in the revision setting. Careful preparation of the diaphysis and intraoperative radiographs are recommended owing to the risk of iatrogenic femur fracture. Short, uncemented, metaphyseal engaging stems have demonstrated a concerning rate of failure in recent series and should not be used. If a short stem is chosen, cementing is a prudent choice.
So-called offset stems may be necessary in the setting of translational deformity to avoid component malposition. Commercially available stems exist that allow the surgeon to choose the optimum stem position. This may be most useful for diaphyseal engaging stems. Shorter, cemented stems often can be “cheated” after overreaming to afford good stability in the face of angular and translational deformities. Again, careful preoperative templating is critical to fully understand the deformity and avoid intraoperative difficulties. Very rarely, a custom component may be necessary.
Choice of Prosthesis Constraint
The posttraumatic knee with a history of knee dislocation is among the most challenging of reconstructions. Residual tibiofemoral subluxation and varying amounts of ligamentous damage can make achieving a balanced arthroplasty in this setting very unpredictable. Careful preoperative examination can alert the surgeon to ligamentous insufficiency that may require the use of more constrained implants.
In general, the implant with the least constraint necessary to provide symmetric flexion and extension gaps and
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satisfactory knee stability should be used. Although posterior cruciate ligament (PCL)–retaining designs may be used in selected situations with minimal deformity, in most posttraumatic cases substitution of the PCL will facilitate correction of deformity and accurate ligament balancing.
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TABLE 19-1 Total Knee Arthroplasty for Posttraumatic Conditions |
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The use of constrained condylar implants is dictated by the status of the collateral ligaments. If these designs are chosen, consideration should be given to the use of a stem on the components owing to the increased forces the bone/implant interface will experience. The young patient with the deficient medial collateral ligament (MCL) presents perhaps the greatest challenge. Advancement of the native MCL or allograft reconstruction of the MCL may be considered in this setting. Data are limited on the optimum reconstruction in this setting. A more neutral limb axis (less overall valgus) should be considered as well.
Hinged implants and tumor prostheses are reserved for low-demand patients with global ligamentous and bony deficiency. Younger active patients may be better served with arthrodesis; however, few are willing to accept this option.
Summary of Clinical Data
A summary of the recent clinical data is found in Table 19-1.
Summary
Posttraumatic conditions of the knee are common, and having effective reconstruction strategies is important. Younger patients are typically candidates for joint-preserving options such as osteotomy or arthrodesis, whereas older patients typically are salvaged with TKA. Attention to specific details preoperatively and intraoperatively is necessary to minimize complications. The vast majority of published series document predictable functional improvement but higher complication rates when compared with primary TKA.
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