CHAPTER SYNOPSIS
This chapter describes an approach to evaluating and treating the irretrievably failed Total Knee Arthroplasty. Surgical options including revision arthroplasty, arthrodesis and amputation are discussed. The technique of Intramedullary Compression Arthrodesis is described in detail and a video of the technique is provided for the reader.
HISTORY/INTRODUCTION/SCOPE OF THE PROBLEM
As our population continues to age and the activity level of older patients increases, new demands are placed on the reconstructive surgeon. Periprosthetic fracture, aseptic loosening, septic failure, and complicated revisions of total knee arthroplasty (TKA) are increasing. As arthroplasty devices remain implanted for longer and longer periods of time, the quality of bone left for revision deteriorates proportionately. All of these issues create significant challenges for the reconstructive surgeon.
Berend and colleagues describe and develop the concept of prosthetic disease. “Prosthetic disease encompasses the life of the patient with his or her prosthesis and represents all the possible failure modes of that prosthesis.” The challenges provided by the multiply revised knee and periprosthetic fractures create challenges that frequently have difficult solutions. The purpose of this chapter is to provide some insight into the potential solutions for these difficult problems.
Fusion of the knee joint has been a standard procedure in orthopedics for decades. In the era of the tuberculous knee, arthrodesis was frequently selected as the preferred method of treatment. In 1932, Key established the principle that rigid stabilization and compressive apposition of the osteotomized surfaces were required to achieve prompt union. In succeeding years, varying degrees of success were achieved with onlay grafts, bone plates, and intramedullary rods. With the advent of antibiotics, the incidence of tuberculosis of the knee declined sharply and knee fusion became less common. By the 1960s, however, the increasing incidence of failed TKA revived interest in the arthrodesis procedure. Modern arthrodesis stabilization procedures include intramedullary rods, external fixation, and, less commonly, bone plates. The advantages of these alternatives have been widely reviewed.
Today, the irretrievably failed TKA is the primary indication for arthrodesis. Specific indications include advanced degenerative joint disease, persistent infection, persistent patellar dislocation or subluxation, and multiple prior knee surgeries with extensive bone loss and inadequate soft tissue stabilization. For obvious reasons, knee fusion is contraindicated in cases of severe ipsilateral hip or ankle disease, severe segmental bone loss, and contralateral amputation.
Throughout the decade of the 1990s, the techniques available for fusion of failed TKA had success rates that were less than fully satisfactory. External fixators were not able to provide postoperative (i.e., dynamic) compression. In addition, the devices were complicated, tedious to apply, and cumbersome for the patient. With bone plates, it was difficult to provide uniform compression across the large osteotomies involved, and again no dynamic compression was possible. Also, the large incision opening required for large plates increased the liability of intraoperative infection in patients who had already shown susceptibility for such complications.
Intramedullary rods offered a number of advantages. They were quick and easy to apply, they provided excellent bending rigidity, and, if adequately cross-locked, they gave good rotational rigidity. Because of the concern for overall rigidity, the early rods were often as large as possible, and one of the more popular, the Neff Rod, extended from the hip to the ankle in the hope of attaining the maximum possible rigidity. To facilitate implantation of this long rod, it was provided in two pieces with a locking fixture in the middle to join the rods together. The femoral and tibial rods were inserted separately and then united at the level of the knee. However, the locking mechanism was so large that the rod could only be removed in cases of subsequent infection by first opening the knee and disrupting the union. If fusion had actually been attained and a decision was made to try to preserve the arthrodesis, this removal became a surgical procedure of monumental difficulty.
INDICATIONS/CONTRAINDICATIONS
The goal of any lower extremity reconstructive procedure is to provide the patient with an opportunity to remain ambulatory. Preservation of a sensate foot is basic to the goal of facilitating ambulation in this generally elderly population. A secondary, but nevertheless important, goal is to provide the patient with a functional, painless knee whenever possible. Today, the single requirement for the creation of a functional knee is an intact extensor mechanism.
The development of modular revision systems for failed TKA has significantly improved the ability of the reconstructive surgeon to recreate a functional knee. The use of augments and stems allows restoration of the joint line and compensation for defects heretofore solvable only by bone grafting. Given collateral ligament competence and an intact extensor mechanism, stabilized reconstruction of the knee is now possible. With most systems, up to 6 cm of bone loss can be successfully replaced with implant augmentation. When defects occur, which require larger defect management, more extensive procedures are required.
Large segmental defects commonly associated with supracondylar fractures above TKA also create significant challenges. Distal femoral allograft replacement has been advocated as a potential solution for this problem.
This form of salvage procedure is accomplished with the use of best-matched distal femoral allografts for the osseous reconstruction of the distal femur. A long-stemmed femoral component, usually of the highly constrained or hinged variety, is then used to stabilize the knee. The femoral component of the knee arthroplasty is first cemented to the allograft, and this composite is then fixed to the patient. Sound fixation of the graft–host bone interface, along with stable ligamentous or hinged control of the knee, is certainly important to the successful outcome of this procedure. Knee dislocation within the procedure has been a reported complication.
In cases of multiple revision failure or other circumstances, particularly those involving extensive loss of periarticular soft tissue stabilization, it may be impossible to exercise the option of revision arthroplasty and an alternative treatment must be considered. In the case of extremely old or infirm patients, the preferred outcome may well be a nonfunctional joint and acceptance of nonambulation rather than to subject such a frail patient to the rigors of additional surgery. For all other patients, the possible treatments are limited to (1) amputation with a postoperative external prosthesis, (2) knee fusion, and (3) (rarely) implantation of one of the current generation of tumor prostheses.
Patients who have large bone defects and yet the extensor mechanism is intact continue to be candidates for reconstructive procedures using tumor replacement prosthesis. There is good evidence that this procedure, even in the elderly, can provide a functional and cost-effective outcome, even if the patient uses the prosthesis for only 1 year.
Individuals who have a nonfunctioning extensor mechanism, regardless of etiology, are faced with the decision of either amputation or arthrodesis. In this group of generally elderly patients, the preservation of a sensate foot is synonymous with the ability to ambulate.
Amputation
Above-the-knee amputation of the limb in combination with an external prosthesis can provide a functional outcome to this difficult situation. Such patients are usually able to perform the activities of daily living with a level of efficiency and personal satisfaction similar to those of an individual with an arthrodesis. However, the energy requirements for ambulation often preclude the patient’s ability to function as a community ambulatory, whereas the patient with an arthrodesis can function in this manner with significantly lower energy requirements. Furthermore, amputation may have a somewhat higher probability for long-term success than the hinged knee prosthesis. These considerations notwithstanding, the amputation option is often rejected by patients for cosmetic and psychologic reasons. For these patients, the arthrodesed knee is often the most suitable alternative.
Arthrodesis
Arthrodesis of the knee for failed TKA has an extremely varied outcome record. Most surgeons today rely on intramedullary fixation as their method of choice. As with the other rods of this vintage, the Neff Rod incorporated no mechanism specifically designed to provide intraoperative compression. If no cross-locking screws are used, dynamic compression is a possibility but at the cost of reduced rotational stability. These shortcomings notwithstanding, the Neff Rod has proved to be a significant improvement over other fixation systems.
Recently, arthrodesis stabilization systems based on shorter rods have become available. These short rod systems include the Wichita Fusion Nail (WFN) and similar custom-made devices. They rely on cross-locking screws to achieve good rotational stability and can be manipulated to impart excellent intraoperative compression. One of these rods, the WFN, includes an ingenious design by which the locking mechanism incorporates a sliding allowance that permits dynamic (postoperative) compression without compromising rotational stability. Early experience with these shorter rods indicates that a high and rapid rate of successful fusion can be expected.
In the case of two-piece intramedullary rods (Neff and WFN), implantation is initiated through a conventional approach to the knee. The medullary canals are reamed and the distal femur and proximal tibia are subjected to transverse osteotomies. Anterior bone blocks are also removed from the distal femur and proximal tibia to facilitate joining of the rods. The rods are then inserted through the knee for the WFN and retrograde through the hip and knee for the Neff rod. Transverse locking screws are then placed through both components with the aid of a drill guide or radiologically assisted positioning. The coupling device is inserted through the anterior window to join the rods at the level of the knee. In the case of the WFN, the coupling device is also used to impart interoperative compression across the osteotomies. Finally, the bone blocks are replaced and the incisions are closed to complete the procedure.
Rotating-Hinge Arthroplasty
In extreme cases, conventional salvage arthroplasty, even with semiconstrained prosthesis, may be inappropriate because periarticular bone loss and the loss of soft tissue constraints are so extensive that adequate stability of the knee joint cannot be achieved. Such instability is likely to be encountered where there is a total loss of the medial collateral ligament and/or major segmental bone loss or comminuted fractures around the knee. In the presence of such extreme deficiencies, consideration is now being given to salvage arthroplasty using second- or third-generation hinged prostheses with rotational capability.
The initial nonrotating-hinged total knee devices were introduced by Waldius and were intended for primary arthroplasty. These early devices had a history of poor outcomes due to high shear stress in the distal (tibial) bone cement mantle and high wear rates at the metal-on-metal articulating surfaces. The cement mantle stresses were due to the rigid fixation used, which could not accommodate the modest axial rotation imposed on the knee by normal gait kinematics. Subsequent design revisions, designated as the rotating-hinge knee prostheses, provide a limited range of axial rotation that appears to have reduced these stresses and the high failure rates in the tibial cement. In addition, polyethylene bearing surfaces have been introduced to alleviate the wear problem. These modifications have indeed been effective in reducing the rate of unsatisfactory outcomes associated with the early nonrotating design. A number of reports are now available that indicate acceptable to good outcomes for the second and third generation designs, which have found acceptance for reconstruction following periarticular resection for neoplasm. These same design features also favor the use of these devices for salvage of failed TKA involving severe instability. A number of papers are now available that report acceptable to good outcomes for treatment of these difficult cases with the newer rotating-hinge prosthesis.
Success in these salvage procedures is facilitated by the availability of modular intramedullary inserts that improve medullary filling and reduce cement mantel thickness. Design features such as metaphyseal sleeves are also helpful in dealing with problems of extensive bone loss where structural bone grafts are required.
Reports of the improved rotating-hinge devices success in treating the most difficult failed TKAs are encouraging but are limited to follow-up times in the range of 2 to 6 years and patient populations of less than 20. Postoperative range of motion, knee function scores, and patient satisfaction were all comparable to those for patients who had undergone simple salvage procedures with less severe complications prior to the index procedure. The overall complication rates could not be established with an acceptable confidence level due to the patient sample size. The actual ratios of complications to patient populations were 3 of 14 (21%) and 8 of 26 (31%), suggesting that some problems are to be anticipated with this procedure. This is not surprising, however, given the extensive preoperative deficiencies with which the surgeons were faced. The most common complication was deep infection, which required aggressive treatment. Intraoperative bone fracture was also encountered and was successfully managed with cerclage wires or cables. Medullary lucency around the implant stem was not frequently mentioned.
The lack of a functioning knee extension mechanism is a contraindication for revision with the rotating-hinged prosthesis. In the case of a deficient extension mechanism that cannot be restored surgically, one of the nonarticulating alternative solutions must be accepted.
While the failed TKA, with severe loss of periarticular bone and ligamentous stability, continues to present the joint reconstruction surgeon with a major challenge, it is reassuring that several salvage procedures are now available that offer acceptable, if not ideal, outcomes. Surgeons who are faced with these cases should persist in looking to future reports on the long-term success of arthrodesis and of arthroplasty with the rotating-hinge prosthesis.
SURGICAL TECHNIQUE FOR INTRAMEDULLARY COMPRESSION ARTHRODESIS WITH THE WICHITA FUSION NAIL
(Note: The following text and images for this section used and adapted with permission from Stryker Wichita Nail.)
Introduction
The Wichita® Fusion Nail ( Fig. 30-1 ) is a device designed to provide simultaneous compression and intramedullary fixation for arthrodesis of the knee. The device is implanted through a single knee incision, using four main components:
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Compression screw component ( Fig. 30-1 A )
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Femoral component, ø18 mm ( Fig. 30-1 B )
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Tibial component, ø12 mm ( Fig. 30-1 C )
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Transverse screws (4) ( Fig. 30-1 D )
The femoral component is bullet shaped with a distal diameter of 18 mm and a proximal diameter of 14 mm. The femoral component inserts retrograde into the distal femur and has two holes in its proximal end to accept transverse screws.
The tibial component has a diameter of 12 mm and inserts antegrade into the proximal tibia. The tibial component has two sets of holes for transverse screw placement. The proximal set of holes is recommended except in cases of inadequate bone quality in the proximal tibia. In these cases, the distal set of holes may be used.
The compression screw component is used to lock together the femoral and tibial components. As the screw is tightened, the cut surfaces of the femur and tibia are drawn together and compression is generated across the joint line.
The 6.0-mm self-tapping transverse screws are available in 25- to 60-mm lengths with 5-mm increments. Using the dedicated Wichita Instrumentation, transverse screws may be positioned without the use of image control.
Preoperative Planning
Preoperative templating is essential for successful implantation of the Wichita Nail ( Fig. 30-2 ). Prior to surgery, anteroposterior and lateral radiographs should be obtained, and templating is performed to ensure proper fit of the implants within the femoral and tibial canals. It is also important at this stage to be sure that the sites of the transverse screw holes will be in bone of good quality.
Natural Valgus Alignment
Although it is very important to restore the natural valgus alignment of the knee in TKA or osteotomies about the knee to provide normal joint mechanics, with knee arthrodesis, the critical issue is efficient placement of the foot at the center of the gravity during normal gait. To be able to accomplish this, the knee has to be arthrodesed in 0 degrees of varus and 0 degrees of valgus or even positioned in slight varus. The act of placing the foot efficiently at the center of gravity during gait reduces the amount of energy required for ambulation.
Incision and Preparation
The knee is approached through a direct mid-line incision using a medial parapatellar approach. The quadriceps muscle is split at the junction of the vastus medialis and quadriceps tendon.
Distal Femoral Cut
A starter hole is created approximately 5 mm anterior to the insertion of the posterior cruciate ligament, using a <SPAN role=presentation tabIndex=0 id=MathJax-Element-1-Frame class=MathJax style="POSITION: relative" data-mathml='516′>516516
5 16
-inch drill bit. A <SPAN role=presentation tabIndex=0 id=MathJax-Element-2-Frame class=MathJax style="POSITION: relative" data-mathml='12′>1212
1 2
-inch drill bit is then used to open the distal femur. After slowly passing an intramedullary alignment guide, the distal femoral cut is made with 0 degrees of varus and valgus, and 0 to 5 degrees of flexion. The level of the cut should be sufficient to expose good trabecular bone.
Technical Hints: Flexion is achieved by reaming perpendicular to the transverse bone cuts. If, for example, 6 degrees of valgus correct varus flexion is desired, both the femur and tibia can be cut into 3 degrees of posterior slope. Once transverse cuts have been made, reaming should start slightly posterior to the center of the shaft and progress slightly anteriorly.
By positioning either the femoral or tibial rod more posteriorly at the articulation, this will allow for 5 to 10 degrees and occasionally more flexion depending on the metaphyseal size.
Since flexion is built into the joint by reaming posterior to anterior, the degree of flexion that can be achieved depends on the size of the femoral canal and thus will vary from patient to patient.
In a large patient, there is more room to safely advance the reamer in an anterior direction. Therefore, a greater degree of flexion can be obtained. In a small patient, the degree of possible flexion will be very limited.
Proximal Tibial Cut
A starter hole is created using a <SPAN role=presentation tabIndex=0 id=MathJax-Element-3-Frame class=MathJax style="POSITION: relative" data-mathml='516′>516516
5 16
-inch drill. After positioning an intramedullary alignment guide, the proximal tibial cut is made with 0 degrees of varus and valgus, and 0 to 5 degrees of flexion. The level of the cut should be sufficient to expose good trabecular bone without undue shortening.
Femoral Reaming
The femoral reamer is used to prepare the femoral canal ( Fig. 30-3 ). Advance the reamer slowly until the circumferential depth marking of the reamer reaches the level of the distal femoral bone cut, and remove.
Related posts:
Soft Tissue Balancing during Total Knee Arthroplasty
Intraoperative Complications during Total Knee Arthroplasty: How to Get Out of Trouble
Addressing Ligament Deficiency in Revision Total Knee Arthroplasty
The Infected Primary Total Knee Arthroplasty
Patellofemoral Maltracking: Identification and Solutions
Adjunctive Fixation in Total Knee Arthroplasty Revision: Stems and Sleeves
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