Assess symptoms, knee function to achieve successful revision TKA outcomes

As the use of primary total knee arthroplasty continues to increase worldwide, knowing the challenges of revision total knee arthroplasty has become increasingly necessary.

Data show an estimated 601% increase in overall revision total knee arthroplasty (TKA) procedures in the United States between 2005 and 2030, for example. To meet this increasing demand, more orthopaedic surgeons must master revision TKA, a procedure that is often more technical, more expensive and more prone to error than primary TKA, according to the experts that spoke with Orthopaedics Today Europe. They agreed surgeons must have a good working knowledge of the principles behind primary TKA before attempting revisions.

That involves first determining why the primary implant failed, according to Jean-Noel A. Argenson, MD, professor of orthopaedic surgery at the Center for Arthritis, Hôpital Sainte-Marguerite, in Marseilles, France, and an Orthopaedics Today Europe Editorial Board member.

“The first and obligatory step is to identify the cause of failure since the absence of identification leads to an unacceptable rate of failure following revision,” Argenson told Orthopaedics Today Europe. “This preoperative planning includes history of failure with pain, swelling, instability or stiffness.”

Image: APHM

But, it should also include an assessment of mobility, extension and mid-flexion stability, function of the extensor mechanism, and the location of scarring, he said.

“You should know why the knee failed and have a plan to solve that problem,” Robert T. Trousdale, MD, a professor of orthopaedic surgery at the Mayo Clinic, in Rochester, Minn., USA, said. “Operating on a knee for persistent pain in the absence of a firm diagnosis is generally a mistake,” he said.

Preoperative steps

The preoperative plan should account for any 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 Thomas Jefferson Hospital/The Rothman Institute, in Philadelphia, said.

Prior to revision TKA, standing antero-posterior and medial-lateral radiographic views help Argenson better understand patellar tracking, component fixation, knee size, and the overall mechanical axis of the limb. However, he said in recent years CT has proved useful for identifying potential sources of infection.

Research by Kevin J. Bozic, MD, MBA, and colleagues showed the most common causes of revision are infection (25.2%), implant loosening (16.1%) and implant failure/breakage (9.7%).

Intraoperative steps

In the operating room, Trousdale said the surgeon must 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 that 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.

“The new thin, oscillating saws are useful at the time of component extraction, as well as high speed burrs,” Argenson said, noting these instruments — and osteotomes — are most effective for revising cemented or uncemented TKA prostheses that are still well-fixed.

Constraint preferences

Surgeons also advised to select revision components with the least amount of constraint that will still result in 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,” he said.

Less constraint in revision TKA is generally accepted, Argenson said, but determining the state of the collateral ligaments is equally important to do before deciding which implants to use. Therefore, he said surgeons should protect collateral ligament function by appropriate positioning of the retractors when performing component removal and making the bone cuts.

“I use only posterior-stabilized primary implants because of the consistent rollback and postoperative flexion achieved with [them] as demonstrated in several clinical and fluoroscopic studies, and this obviously influences my choice for revision, using the same type of implants when easily possible to equalize flexion and extension spaces,” Argenson said.

However, “When this is not possible — and when bone loss requires the use of augments or grafts — I routinely use intramedullary stems combined with more constrained implants in order to reduce the stress at the bone-implant interface,” he said.

Surgeons said critical steps in these revision procedures also include balancing the knee ligaments and careful 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, either by increasing the femoral component size or moving 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.

Bone reconstruction, which is frequently a part of TKA revision surgery, has seen many recent advances. Historically, surgeons used cement or metal fillers to fill bone defects, but concerns arose about how well those fillers were fixed to the residual bone. Now, there are various techniques that fill the defects and provide secure bony fixation, including morselized grafts, structural allografts, wedges, and metal augments, as well as metaphyseal cones and stems.

“Each is useful in its own way, depending on the size and location of the defect,” Trousdale said.

Francesco M. Benazzo, MD, of University di Pavia, in Pavia, Italy, uses cones made of Trabecular Metal Technology (Zimmer; Warsaw, Ind., USA). They help correct bone gaps after primary TKA, he told Orthopaedics Today Europe.

“Bone defects must be corrected and filled in order to provide the [revision] implant with the best available surface for primary fixation, and in the case of uncemented components, for secondary osteointegration,” Benazzo said.

“My experience is based upon the use of the Trabecular Metal (TM) cones, both on the tibia and on the femur. The porous structure of TM is an osteoconductive surface with a high friction coefficient that provides a sound primary fixation to the bone, while the TKA components are fixed to the inner surface of the cones with a cement mantle,” he said.

Patellar revisions, resurfacing

Management of the patella during revision TKA is an area that can be addressed with various approaches.

“The unresurfaced patella is usually deformed in a revision and it must be reshaped and adapted,” Benazzo told Orthopaedics Today Europe. “The plastic button can be implanted in an appropriate position if the patella is high or low riding in order to obtain the best tracking,” he said.

When the patella cannot be resurfaced, Benazzo recommended performing longitudinal resection of the bone in the middle of the patella to create a “gull wing” effect, which he said will better adapt the patella to the implant. Newer techniques, such as bone grafting, porous tantalum patella reinforcement, and cementing a plastic button on porous tantalum surfaces are also useful ways to reconstruct the patella, he noted.

Trousdale said his group has attained good results using morselized autograft or allograft to reconstitute patellar bone stock in the face of significant bone loss.

Argenson also resurfaces the patella during revision TKA, but said he pays close attention to femoral and tibial rotation because they are the reason for patella failure in most patients. Preserving the patella is important during a resurfacing procedure so that you have a place to put the revised patella component, he added.

“At the time of reconstruction, the TM shell combined with impaction grafting may also help the surgeon reconstruct a damaged patella,” Argenson said.

Follow usual rules for infection

Benazzo said he believes the rules for primary TKA should also apply to preventing infection in revision TKA.

A painful primary TKA, he said, could be caused by an infection. As such, the following rules should be kept in mind when managing infection:

• Test the patient for infectious foci, such as urinary tract infection or methicillin-resistant Staphylococcus aureus or MRSA;
• Confirm that the primary TKA did not fail because of a previous infection;
• Manage all comorbidities, such as diabetes, obesity or patients who are immunocompromised;
• Choose the most appropriate surgical incision based upon the previous scars;
• Reduce the time of exposure through preoperative planning, facilitating the amount of opened trial components and the number and flow of the instruments used; and
• Apply vancomycin over the course of the surgery.

According to Argenson, “Symptoms like lack of pain relief, swelling, wound healing problems, signs of acute inflammation and temperature may alert the surgeon and orient him to detect infection.”

Revision requires good primary background

Regardless of which approaches are used for revision TKA, sources agreed that an extensive background with primary TKA supports performing successful revision surgery.

“All these aspects related to revision TKA, including preoperative planning, surgical exposure, component removal, reconstruction procedures, and implant constraint choice require a good knowledge of the basic principles encountered in primary TKA before performing revision TKA on a regular basis,” Argenson said. “The most complex revision cases should be ideally referred to high-volume centers that include surgeons with large-scale experience with revision and access to any type of technology for reconstructive procedures.”

Benazzo said that although there is no clear guidance about how much experience a surgeon needs prior to performing revision TKA, specialized surgeons operating at centers dedicated to revision TKA surgery could reduce costs associated with the procedure.

“A knee revision surgeon should deal with at least one or two cases per week, and at least 100 primary cases per year to acquire the needed experience,” Benazzo said.

The surgeons noted 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.

“Execute the surgery fast, but appropriately,” Parvizi said. “The surgeon needs to ensure that the postoperative care is meticulous, watching these people for wound-related and skin-related issues and to ensure that these patients are given appropriate prophylaxis.”

All of this requires training and expertise. At a minimum, orthopaedic 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.

“I personally think [revision TKAs] should be performed at high-volume centers where protocols are in place,” and where medical care is in place, Parvizi said. “These patients are more likely to have complications. They will require more postop surveillance and care than primaries.” – by Jeff Craven and Colleen Owens

• References:
• Bozic K. Clin Orthop Rel Res. 2010; doi:10.1007/s11999-009-0945-0.
• Kurtz S. J Bone Joint Surg Am. 2007; doi:10.1007/s11999-009-0834-6.

• For more infromation:
• Jean-Noel A. Argenson, MD, can be reached at Aix-Marseille University, 270, Boulevard Sainte-Marguerite, 13009 Marseille, France; email: jean-noel.argenson@ap-hm.fr.
• Francesco M. Benazzo, MD, can be reached at Clinica Ortopedica e Traumatologica, Universita di Pavia, Fondazione IRCCS, Policlinico San Matteo, Piazzale Golgi, 27100 Pavia, Italy; email: f.benazzo@smatteo.pv.it.
• Javad Parvizi, MD, FRCS, can be reached at 925 Chestnut St., Philadelphia, PA 19107, USA; email: parvj@aol.com.
• Robert T. Trousdale, MD, can be reached at 200 First St., Rochester, MN 55905, USA; email: trousdale.robert@mayo.edu.

Disclosures: Argenson is a consultant to Zimmer. Benazzo is a consultant to Zimmer and Lima Corporation. Parvizi is a paid consultant to Zimmer, Smith & Nephew, Convatec, Ceramtec, Cadence, 3M and Tissuegene. Trousdale receives royalties from DePuy and Wright Medical.

 

What are the indications for partial vs. complete revision total knee arthroplasty?

Partial revision sparsely indicated

Generally, we see few indications for only a partial revision or exchange during revision total knee arthroplasty (TKA).

According to our experience and correlating evidence in the literature, major indications for TKA revision remain ligament instability and component loosening. Due to associated bone loss in even partial implant removal scenarios, usually stem extensions, augments or bone grafting becomes necessary. In those cases, usually at least some change to a higher constraint system becomes necessary, which excludes a partial revision for most TKA systems on the market. In addition, we often find associated rotational and/or oversizing issues with the correlating implant part, which leads to removal of this part as well.

It is obligatory, however, to perform a complete exchange in the presence of a periprosthetic infection.

However, a partial exchange makes sense in some indications, such as for an isolated polyethylene revision in conjunction with either early wear or intended increase of tension by elevation of the liner. This might also include the downsizing of the tibial implant, in cases of arthrofibrosis with an associated soft tissue release or isolated malrotation, or oversizing of either the tibial or femoral components.

Thorsten Gehrke, MD, is medical director of the ENDO-Klinik Hamburg, in Hamburg, Germany.
Disclosure: Gehrke is a consultant to Zimmer and LINK.

Revision depends on patient infection

Whether I do a total revision or a partial revision depends on the status of the knee. You should divide patients into two types: with and without an infection.

In patients without an infection, I look for mobilization of the prosthesis. Usually, I do a CT scan and a bone scan to check if there is mobilization of one of the components. After that, I change any part that is loose. However, if both components are loose, then I do a complete revision. This is when you have an aseptic patient.

The second type of patient is when you have a patient with an infection and in this case usually I do a two step revision – I clean the joint and put in a cement spacer with antibiotics, and after 3 months or 4 months, I perform a total revision of the prosthesis.

The most important is to order X-rays, CT scans and bone scans. A local bone scan is important to check if there is mobilization or infection of the prosthesis.

Matteo Denti, MD, is chief of the Sports Traumatology and Arthroscopic Surgery Unit at Galeazzi Institute, in Milan, and vice president of the European Society of Sports Traumatology, Knee Surgery and Arthroscopy.
Disclosure: Denti has no relevant financial disclosures.