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Top surgeons offer tips to obtain a durable, stable, well-functioning revision TKA
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Revision total knee arthroplasty is a technically challenging procedure that has simple goals: to relieve pain and improve mobility.
The number of primary total knee arthroplasties (TKAs) is increasing dramatically — more than 600,000 patients per year undergo primary TKA in the United States, according to the Centers for Disease Control and Prevention.
Consequently, rates for revision procedures are also increasing significantly. Using the Nationwide Inpatient Sample and the United States Census Bureau data, Steven Kurtz, PhD, and colleagues found that the rate of overall revision TKA is estimated to grow 601% between 2005 and 2030.
To meet this increasing demand, orthopedic surgeons must understand the critical steps for a successful revision knee surgery.
In revision cases with multiple incisions around the knee, Robert T. Trousdale, MD, recommends surgeons use the most acceptable lateral-based incision.
Image: Mayo Clinic
Preoperative planning is the most critical piece of revision knee surgery, and the first step of preoperative planning is to determine why the index procedure failed.
“You should know why the knee failed and have a plan to solve that problem,”
This step will prevent the revision surgeon from simply repeating the problem,
A recent study by Kevin J. Bozic, MD, MBA, and colleagues found the most common causes of revision are infection (25.2%), implant loosening (16.1%) and implant failure/breakage (9.7%).
Once the etiology of the failure has been established, the surgeon must plan the revision procedure. The first step is to collect a thorough patient history, which should include the date the original component was implanted, a description of any problems the patient encountered postoperatively and current symptoms, Scuderi said.
Next, the surgeon should complete a meticulous physical exam that assesses limb alignment, the surgical scar, range of motion, stability, integrity of the extensor mechanism and the neurovascular status.
Giles R. Scuderi
A series of X-rays should highlight component position and size as well as reveal areas of possible bone loss, subsidence and fracture, Scuderi said.
More recently, some surgeons have been used CT scans and MRIs to diagnose why the primary procedure failed.
“But the majority of the time, the diagnosis can be made with a good history, physical examination and the appropriate X-rays,” Scuderi said.
The preoperative plan must also account for potential problems.
“You have to anticipate what your problems are going into the operating room and have all of the plans in place [to address them],” Javad Parvizi, MD, FRCS, director of clinical research at the Rothman Institute in Philadelphia, told Orthopedics Today.
Intraoperative steps
In the operating room, Trousdale said the surgeon must first get adequate exposure.
“We usually use the old incision if it is in an acceptable location,” he said. “If there are multiple incisions around the knee, you want to use the most acceptable lateral-based incisions.”
To prevent skin necrosis, Trousdale suggested surgeons not cross any incision at an angle less than 60°.
For most of the revisions he performs, Trousdale does an extensile exposure involving a medial peripatellar approach.
The next step is component removal. With a well-fixed cemented component, Scuderi prefers to use a microsagittal saw blade. He will use small, flexible osteotomes to carefully separate the femoral and tibial components at the cement prosthetic interface. When faced with a well-fixed cementless implant, Scuderi uses a microsagittal saw blade on the prosthetic-bone interface and flexible osteotomes. The goal is to preserve the bone, which is the “foundation for the following re-implantation.”
For challenging cases, Scuderi may opt to disassemble implants with modular components.
When faced with a well-fixed cementless implant, Scuderi uses a microsagittal saw blade on the prosthetic-bone interface and flexible osteotomes.
“The surgeon must be cautious when removing the implants,” Scuderi said. “I am stressing this point emphatically: Be patient and careful when removing well-fixed components. Do not damage the residual bone.”
Once he removes the components, debrides the interfaces and prepares the bone for re-implantation, Scuderi accesses the tibial and femoral bone, along with the supporting soft tissue structures, which is critical to the success of the revision. From this point, he embarks on a three-step process for re-implantation.
“The tibia is addressed first since it is the platform upon which the implant will be constructed,” he said. “The tibia influences both the flexion and extension gaps, so I believe it should be reconstructed in the first step. Once I have re-established the tibial platform perpendicular to the mechanical axis, I turn my attention to the femoral component and select the appropriate size and set it in the appropriate rotation to accommodate the flexion gap. This is then followed by establishing the distal joint line and extension gap.”
When selecting the new components, Scuderi said to choose one that is appropriate for both the femur and the tibia, restores the knee anatomy and accommodates the flexion and extension gaps. Surgeons can rely on radiographs of the contralateral knee for size comparisons during the procedure.
Use the least constrained implant
Surgeons also advised to pick the component with the least amount of constraint that will still provide a stable knee.
“The least constraint is optimal,” Parvizi, who is an Orthopedics Today Editorial Board member, said. “The more constraint you use, the worse the outcome is in the long run. More constraint can lead to loosening of the component at an early stage.”
However, “sometimes, the bone loss is so extensive, it begins to infringe upon the ligament attachments,”
Balancing the knee ligaments is critical, Scuderi said. While it is unusual to require soft tissue releases in revision procedures, there are some cases in which they are necessary.
“In a situation where there is a fixed varus deformity, there may be a need to perform a medial soft tissue release to balance the knee and correct the alignment,” he said. This is then followed by measurement of the flexion and extension gaps.
“The vast majority of these — more than 90% of the time — the flexion space is going to be bigger than your extension space.” Trousdale, who is an Orthopedics Today Editorial Board member, said. There are a few ways to decrease the flexion space: increase the femoral size or move the femoral component as posterior as possible with the help of offset stems. “On occasion, one has to elevate the joint line a few millimeters to get the gaps close to even,” Trousdale said.
Soft tissue management
Revision TKA is not a minimally invasive procedure, so the incision must be appropriately sized,
Bolognesi also performs a full synovectomy on revision knees to help with exposure.
“After performing a synovectomy, the posteromedial release and the snip, I think you also need to be comfortable moving quickly to some sort of work at the tubercle if needed,” Bolognesi said. “You want to make sure that you get adequate exposure before you start working on the implants.”
It is also important to preserve the existing tissues, particularly the extensor mechanism and the collateral ligaments, by using retractors when removing the old implant, Vail said.
“It is a matter of getting into those interfaces between the implant and the bone to disrupt the interface so the implant is removed with a limited amount of bone/soft tissue that could be critical later to the stability of the knee,” Vail said.
Some soft tissue defects require the help of a plastic surgeon, Trousdale said. In the event of a catastrophic problem like an extensor mechanism disruption, the surgeon must reconstruct the extensor mechanism, which can be done with an allograft. The Mayo Clinic currently uses the Marlex mesh technique, he said.
Bony reconstruction
In terms of technology and devices, Vail said that bone reconstruction has seen the most recent advances. Historically, surgeons have used cement or metal fillers to fill bone defects; however, there were concerns about how well the filler was fixed to the residual bone. Now, there are various techniques that fill the defects and have secure bony fixation, including morselized grafts, structural allografts, wedges, and metal augments as well as metaphyseal cones and stems.
Michael P. Bolognesi
“Each is useful in its own way, depending on the size and location of the defect,” Trousdale said.
The appropriate bone reconstruction option depends on the degree of bone loss. Scuderi uses the Anderson Orthopaedic Research Institute bone defect classification system, which categorizes bone loss as types 1, 2 and 3 depending on the integrity of the metaphyseal bone and subclassified as A or B, if one or both condyles are involved.
Grade 1 bone loss indicates there is good integrity of the metaphyseal bone, which can be addressed with cement or impaction grafting, Scuderi said. In general, these defects are less than 5 mm deep.
For the larger grade 2 defects, Scuderi said that many can be filled with modular augments. Structural allografts, such as femoral heads, are useful in grade 2 cavitary defects.
When faced with a severe grade 3 defect, which are proximal to the femoral epicondyles or distal to the tibial tubercle, the options are metaphyseal cones; structural allografts or, in some cases a tumor prosthesis; a distal-femoral replacement or proximal tibial replacement, according to Scuderi.
“Those are significant cases, usually related to severe osteolysis, re-revision or fracture in which the bone loss is significant, cannot be reconstituted and may need to be replaced with a megaprosthesis,” he said.
Metaphyseal cones and stems
Of these bone reconstruction options, metaphyseal cones and stems have been increasing in popularity. They are indicated for metaphyseal defects that are too large for cement alone or when the defect in combination with periarticular bone damage compromises fixation, Vail said. Cones fill the defect and attach the implant to the bone.
“Many of these new cones and fillers are porous, so that bone will attach itself to those materials,” Vail said.
Bolognesi said the short-term data supports the efficacy of these devices. “Of course, you need longer term follow-up to be sure that this is superior to a large allograft approach.”
For example, a study by R. Michael Meneghini, MD, and colleagues showed that at short-term follow-up, porous tantalum-metaphyseal cones provided structural support for the tibial implants. The study included 15 patients who had an average of 3.5 prior TKAs. Eight knees had type III defects; seven had type 2B defects. The researchers followed the patients for 34 months.
The average Knee Society clinical scores improved from 52 points preoperatively to 85 points at final follow-up. All 15 metaphyseal cones had signs of osseointegration with reactive osseous trabeculation at points of contact with the tibia. The researchers saw no evidence of loosening or migration.
Patellar revision options
For patellar revision, if the patella is well fixed and the polyethylene surface looks good, Scuderi will leave it alone. If the patellar component is loose or malpositioned, he will revise it.
Trousdale said his group has been getting good results using morselized autograft or allograft to reconstitute the patellar bone stock in the face of significant bone loss.
Scuderi noted a bone graft technique for filling patellar cavitary defects described Arlen D. Hanssen, MD. Instead of performing either a patellectomy or keeping the patellar osseous shell, Hanssen created a tissue flap that he secured to the patellar rim in nine knees, and creating a pocket that he filled with cancellous bone graft and inserted into the defect.
Thomas P. Vail
The results showed dramatic improvements in Knee Society Scores. Preoperative scores were 39 points for function and 40 points for pain. At final follow-up, the mean function score increased to 91 points while the mean pain score was 84 points.
“He has shown that the bone graft reconstitutes the patella, and provides adequate bone for the patella and the integrity of the extensor mechanism,” Scuderi said.
In addition, Scuderi will opt for a trabecular metal augment, which he sutures into place on the residual bone to reconstitute the surface. This provides a foundation on which he can cement a polyethylene patellar bone. So far, he has seen good results with the trabecular augmented patellar button.
Complications
“All of the complications that can happen with a primary knee surgery can happen with revision knee surgery; they are probably just more common,” Trousdale said.
Topping the list is infection.
“Infection rates are higher after revision surgery than after primary surgery,” Trousdale said.
There can be ligament issues and component fixation problems. Osteolysis occurs, but not as often as in primary procedures.
“The reason for that is the revision population is older and less active,” Trousdale said.
Avoidance of these complications comes down to preparation, with Trousdale noting that surgeons should use antibiotics to ward off infection, handle the soft tissue appropriately and take care with wound management.
Ideal revision knee surgeon
The surgeons noted that a successful revision TKA comes down to the following basic, but critical steps: preserve the residual bone, balance the gaps, fill the defects and fix the implants to the underlying skeleton.
The surgeon must be quick during surgery and careful during the postoperative period.
“Execute the surgery fast, but appropriately,” Parvizi said. “The surgeon needs to ensure that the postoperative care is meticulous, watching these people for wound- and skin-related issues and ensure that these patients are given appropriate prophylaxis.”
All of this requires training and expertise. At a minimum, orthopedic surgeons who perform revision TKA should be trained in knee arthroplasty, preferably with fellowship training.
“I think any knee arthroplasty surgeon who is doing a high volume of primary knee surgery is probably capable of doing the vast majority of knee revision surgeries,” Trousdale said.
Ideally, these surgeons would be based in high-volume centers.
“I personally think [revision TKAs] should be performed at high-volume centers where protocols are in place,” Parvizi said. “They should [be performed at] centers where medical care is in place. These patients are more likely to have complications. They will require more postop surveillance and care than primaries. Revision TKA should be reserved for centers that have the necessary infrastructure in place.” – by Colleen Owens
References:
Bozic K, Kurtz SM, Lau E, et al. The epidemiology of revision total knee arthroplasty in the United States. Clin Orthop Rel Res. 2010;468:45-51.
Centers for Disease Control and Prevention FastStats Inpatient surgery. www.cdc.gov/nchs/fastats/insurg.htm.
Hanssen AD. Bone-grafting for severe patellar bone loss during revision knee arthroplasty. J Bone Joint Surg Am. 2001;83:171-176.
Kurtz S, Ong K, Lau E, Mowat F, et al. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am. 2007;89:780-785.
Meneghini RM, Lewallen DG, Hanssen AD, et al. Use of porous tantalum metaphyseal cones for severe tibial bone loss during revision total knee replacement. J Bone Joint Surg Am. 2008;90:78-84.
For more information:
Michael P. Bolognesi, MD, can be reached at Duke University Medical Center, Box 3269, Hospital South, Orange Zone, Room 5316, Durham, NC 27710; email: michael.bolognesi@duke.edu.
Javad Parvizi, MD, FRCS, can be reached at the Rothman Institute, 925 Chestnut St., Philadelphia, PA 19107; email: parvj@aol.com.
Giles R. Scuderi, MD, can be reached at the Insall Scott Kelly Institute, 210 East 64th St., 4th Floor, New York, NY 10021; email: gscuderi@iskinstitute.com.
Robert T. Trousdale, MD, can be reached at the Mayo Clinic, 200 First St., Rochester, MN 55905; email: trousdale.robert@mayo.edu.
Thomas P. Vail, MD, can be reached at University of California, San Francisco, 500 Parnassus Ave., MU320W, San Francisco, CA 94143; email: vailt@orthosurg.ucsf.edu.
Disclosures: Bolognesi is a paid consultant for Zimmer and Biomet, and a design surgeon for Zimmer and Biomet; Parvizi is a paid consultant for Zimmer, Smith & Nephew, Convatec, Ceramtec, Cadence, 3M and Tissuegene; Scuderi is a design surgeon and a consultant for Zimmer and a consultant to Medtronic and Convatec; Trousdale receives royalties from DePuy and Wright Medical; and Vail is a paid consultant for DePuy on total knee products.
What are the indications for partial vs complete revision total knee arthroplasty?
Polyethylene wear is the most common indication for a partial revision or liner exchange in revision total knee arthroplasty (TKA). This usually manifests initially at 5 years to 8 years after a primary TKA as an effusion or synovitis in the knee. The pain level reported by the patient is variable, and many are asymptomatic. There may be subtle varus-valgus instability in extension or flexion. Radiographs may disclose osteolysis, usually seen as an oval, well-circumscribed lesion at the medial tibial plateau margin or in the medial femoral condyle. These small lesions may be overlooked on a cursory glance of the radiographs.
In my decision-making to proceed with a liner exchange, six specific criteria must be present: well-fixed implants; alignment between 3° and 9° tibiofemoral valgus; liner availability from the manufacturer; intact tibial tray locking mechanism; small-to-moderate size, non-structural osteolysis; and the implant should have a known, published good (>90%) survival at 10 years. If these six criteria are present, the revision includes a synovectomy, liner exchange and curettage with bone grafting of all osteolytic lesions. Full weight-bearing and early range of motion exercises are recommended.
Paul F. Lachiewicz
Less frequent indications for a partial revision knee arthroplasty include: isolated femoral component loosening with a well-fixed and perfectly positioned tibial component; patella resurfacing in a previously unresurfaced patella; and selected cases of instability, in which a liner exchange alone may be effective. A systematic review of fractures of a tibial post of a posterior-stabilized TKA has shown that liner exchange is usually successful. Finally, and although controversial, liner exchange is usually performed as part of a debridement procedure when attempting to retain a TKA with an acute postoperative or late metastatic infection.
Liner exchange is never indicated for the treatment of a chronic infection, malrotation of components with patella instability or the painful, stiff knee. In these situations, there is little or no chance of success with less than a complete revision.
Paul F. Lachiewicz, MD, is an attending surgeon at Chapel Hill Orthopedics Surgery and Sports Medicine and consulting professor in the Department of Orthopaedic Surgery at Duke University, Durham, N.C.
Disclosure: Lachiewicz is on the speaker’s bureau for Cadence Pharmaceuticals, and his institution receives research support from Zimmer.
The indication for partial vs. complete total knee revision is based upon the reason for revision. Components should be revised if malpositioned, inappropriately sized, not well-fixed to the bone, damaged, have a poor track record or if revision to a higher level of constraint is necessary. Some older implants may not have compatible parts available. Occasionally, the use of metaphyseal fixation for cases with massive bone loss or the need for a hinged or megaprosthesis may necessitate revision of the other implant to a compatible prosthesis. Mid-term follow-up has shown 100% survivorship in a series of tibial revisions in which the femoral component was retained. In contrast, isolated polyethylene exchange should be performed with caution due to a higher failure rate reported in some studies. Furthermore, it has been shown that the patella component can be retained at the time of revision surgery if it meets the above criteria and is not oxidized.
Matthew S. Austin
In summary, isolated component revision can be performed as long as the parts are well-fixed, not significantly damaged and retention is technically feasible. The surgeon must weigh the advantage of revising more than one implant against the potential for iatrogenic bone loss, increased operative time, expense and increase in revision complexity associated with multi-component revision. The decision-making algorithm must be individualized for each patient under the surgeon’s care.
Matthew S. Austin, MD, is an associate professor in the Department of Orthopaedic Surgery, Division Chief and Fellowship Director of Adult Reconstruction at Thomas Jefferson University Hospital/The Rothman Institute, Philadelphia.
Disclosure: Austin receives research support from DePuy, is a consultant for Zimmer and Biomet, and receives royalties from Zimmer.